Arts and Sciences, Irving K. Barber School of (Okanagan)
Chemistry, Department of (Okanagan)
DSpace
UBCO
Liu, Ying
Doctor of Philosophy - PhD
University of British Columbia
Protein malnutrition is a leading cause of child mortality and chronic development disorders in the tropics. This study evaluated the protein quality of breadfruit using three standards measures: (1) yield of fruit and production of protein, (2) the protein content and amino acid profile, and (3) the protein digestibility/amino acid availability. I analyzed field data collected from 2006 to 2012 from 24 breadfruit cultivars in National Tropical Botanical Garden in Kauai, Hawaii. Based on a plant density of 100 trees/ha, breadfruit can yield 10-14 tons of fruit/ha. The commercial cultivar Ma’afala can produce up to 0.52 t/ha of protein. This is higher than wheat, rice, cassava, and potato. To determine the quality of breadfruit protein, I conducted an amino acid analysis of 49 breadfruit cultivars using high performance liquid chromatography with fluorescence detection and determined that the full spectrum of the essential amino acids were present in all cultivars. Breadfruit is especially rich in phenylalanine, leucine, isoleucine, and valine. Ma’afala contained a higher total essential amino acid content than many other staples including wheat, corn, rice, soybean, and yellow pea. To determine breadfruit protein digestibility, I developed a human digestion model, and found that Ma’afala protein was 10-25% more digestible than wheat protein. Ma’afala and wheat protein were compared using a human intestinal epithelial cell model. The results showed that Ma’afala induced similar impact on cell morphology and cytokine production in the model. To determine the overall effect on health, I compared breadfruit and wheat diet in a standard rodent model. The results show that the breadfruit diet did not induce any adverse effects on the overall health or growth of the mice. Breadfruit-fed mice gained more weight overall than wheat-fed mice but the crumbly nature of the diet made accurate food intake measures impossible. Chemical and histological analysis did not reveal any significant difference between the two diet groups suggesting that breadfruit is not toxic. Together, these data demonstrate that breadfruit has potential as a staple protein source for reducing malnutrition in tropical countries and as an ingredient in nutritional products, in particular gluten-free food products, for world markets.
Evaluation of Breadfruit (Artocarpus altilis and A. altilis X A. mariannensis) as a Dietary Protein Source by Ying Liu B.Sc. (Hons.), Dalhousie University, 2012 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in The College of Graduate Studies (Biochemistry and Molecular Biology) THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan Campus) April 2016 © Ying Liu, 2016 The undersigned certify that they have read, and recommend to the College of Graduate Studies for acceptance, a thesis entitled: Evaluation of Breadfruit (Artocarpus altilis and A. altilis x A. mariannensis) as a Dietary Protein Source Submitted by Ying Liu in partial fulfillment of the requirements of The degree of Doctor of Philosophy . Dr. Susan Murch, Chemistry Supervisor, Professor (please print name and faculty/school above the line) Dr. Deanna Gibson, Biology Supervisory Committee Member, Professor (please print name and faculty/school in the line above) Dr. Paula Brown, Biology Supervisory Committee Member, Professor (please print name and faculty/school in the line above) Dr. Ian Walker, Biology University Examiner, Professor (please print name and faculty/school in the line above) Dr. Nyree Zerega, Northwestern University External Examiner, Professor (please print name and university in the line above) April 20, 2016 (Date submitted to Grad Studies) Additional Committee Members include: Dr. Fred Menard, Chemistry Please print name and faculty/school in the line above Dr. Miranda Hart, Biology Please print name and faculty/school in the line above iii Abstract Protein malnutrition is a leading cause of child mortality and chronic development disorders in the tropics. This study evaluated the protein quality of breadfruit using three standards measures: (1) yield of fruit and production of protein, (2) the protein content and amino acid profile, and (3) the protein digestibility/amino acid availability. I analyzed field data collected from 2006 to 2012 from 24 breadfruit cultivars in National Tropical Botanical Garden in Kauai, Hawaii. Based on a plant density of 100 trees/ha, breadfruit can yield 10-14 tons of fruit/ha. The commercial cultivar Ma’afala can produce up to 0.52 t/ha of protein. This is higher than wheat, rice, cassava, and potato. To determine the quality of breadfruit protein, I conducted an amino acid analysis of 49 breadfruit cultivars using high performance liquid chromatography with fluorescence detection and determined that the full spectrum of the essential amino acids were present in all cultivars. Breadfruit is especially rich in phenylalanine, leucine, isoleucine, and valine. Ma’afala contained a higher total essential amino acid content than many other staples including wheat, corn, rice, soybean, and yellow pea. To determine breadfruit protein digestibility, I developed a human digestion model, and found that Ma’afala protein was 10-25% more digestible than wheat protein. Ma’afala and wheat protein were compared using a human intestinal epithelial cell model. The results showed that Ma’afala induced similar impact on cell morphology and cytokine production in the model. To determine the overall effect on health, I compared breadfruit and wheat diet in a standard rodent model. The results show that the breadfruit diet did not induce any adverse effects on the overall health or growth of the mice. Breadfruit-fed mice gained more weight iv overall than wheat-fed mice but the crumbly nature of the diet made accurate food intake measures impossible. Chemical and histological analysis did not reveal any significant difference between the two diet groups suggesting that breadfruit is not toxic. Together, these data demonstrate that breadfruit has potential as a staple protein source for reducing malnutrition in tropical countries and as an ingredient in nutritional products, in particular gluten-free food products, for world markets. v Preface A version of the thesis has been prepared for a GRAS application to the U.S. Food and Drug Administration for the regulation of breadfruit as a safe food ingredient. Ying Liu and Susan Murch (2015). Breadfruit (Artocarpus altilis and Artocarpus altilis x Artocarpus mariannensis) Generally Recognized As Safe (GRAS) notice. USDA. Some of the information in Chapter 1 has been published in the review article: Christina Turi, Ying Liu, Diane Ragone, and Susan Murch. (2014). Breadfruit (Artocarpus spp.): A traditional crop with the potential to prevent hunger and mitigate diabetes in the Tropics. Trends in Food Science and Technology, 45, 267-272. I critically reviewed the literature, and shared this information with the author groups. I also summarized and wrote some significant sections for the paper. A version of Chapter 2 has been published. Ying Liu, Maxwell P. Jones, Diane Ragone, and Susan Murch. (2014). Crop productivity, yield and seasonality of breadfruit (Artocarpus spp., Moraceae). Fruits 69,345-361. I conducted the data analysis, and wrote most of the original draft of the paper. A version of Chapter 3 has been published. Ying Liu, Diane Ragone, and Susan Murch. (2015). Breadfruit (Artocarpus altilis): A source of high quality protein for food security and novel food products. Amino Acids, Online, DOI 10.1007/s00726-015-1914-4. vi I modified and developed the methods, conducted the majority of the experiment and analyzed all of the data. I also critically reviewed the literature, summarized and graphed all of the data and wrote the original draft of the paper. A version of Chapter 4 is being prepared for publication. A version of Chapter 5 is being prepared for publication. Presentations: Data from Chapter 2, 3, and 4 were presented at: Liu Y., Ragone D., Gibson D., Murch S. Breadfruit: a source of high quality protein. Annual Biology Graduate Symposium. University of British Columbia, Kelowna, BC. September 11th 2015. Liu Y. and Murch S. Breadfruit: Breadfruit (Artocarpus altilis, Parkinson (Fos)) for Food Security and Novel Food Products. Botany 2015, Edmonton, AB, Canada, July 25th – 29th 2015. Liu Y. and Murch S. Love it or hate it, you gotta eat it. Three Minutes Thesis, University of British Columbia, Kelowna, February 26th 2014 vii Table of Contents Abstract ................................................................................................................... iii Preface ...................................................................................................................... v Table of Contents ................................................................................................... vii List of Tables .......................................................................................................... xii List of Figures ........................................................................................................ xv List of Symbols and Abbreviations ..................................................................... xix Acknowledgements .............................................................................................. xxi Dedication ........................................................................................................... xxiii Chapter 1. Introduction ......................................................................................... 1 1.1. History of breadfruit consumption ......................................................... 1 1.2. Current uses and significance of breadfruit in the world ....................... 4 1.3. Breadfruit botanical description ............................................................. 5 1.4. Current breadfruit nutritional analysis ................................................... 6 1.4.1. Carbohydrates .................................................................................... 14 1.4.2. Carotenoids ........................................................................................ 16 1.4.3. Minerals .............................................................................................. 18 1.4.4. Vitamins .............................................................................................. 21 1.4.5. Anti-nutrients ...................................................................................... 21 1.5. Study rationale and objectives ............................................................ 24 Chapter 2. Seasonality, Productivity, and Yield of Breadfruit ......................... 25 2.1. Synopsis ............................................................................................. 25 2.1.1. Objectives ........................................................................................... 26 2.2. Materials and methods ....................................................................... 26 viii 2.2.1. Germplasm repository ......................................................................... 26 2.2.2. Data collection ..................................................................................... 27 2.3. Results ................................................................................................ 29 2.3.1. Time from planting to fruit production .................................................. 29 2.3.2. Breadfruit seasonality .......................................................................... 33 2.3.3. Breadfruit productivity/fruit number ...................................................... 41 2.3.4. Breadfruit fruit weight........................................................................... 44 2.3.5. Breadfruit yield .................................................................................... 45 2.3.6. Tree size and growth ........................................................................... 46 2.3.7. Commercial breadfruit Ma’afala ........................................................... 47 2.4. Discussion .......................................................................................... 48 2.4.1. Breadfruit seasonality and production in Kauai ................................... 48 2.4.2. Comparison of breadfruit productivity across locations ....................... 49 2.4.3. Comparison of breadfruit seasonality across locations........................ 54 2.4.4. Commercial breadfruit Ma’afala ........................................................... 54 2.5. Summary ............................................................................................ 56 Chapter 3. Amino Acid Analysis of Breadfruit Protein .................................... 57 3.1. Synopsis ............................................................................................. 57 3.1.1. Objectives ............................................................................................ 58 3.2. Materials and method ......................................................................... 58 3.2.1. Breadfruit sample collection and preparation ..................................... 58 3.2.2. Reagents ............................................................................................ 61 3.2.3. Preparation of amino acid samples .................................................... 61 3.2.4. Derivatization of amino acids .............................................................. 62 3.2.5. HPLC analysis .................................................................................... 62 ix 3.2.6. Data analysis ...................................................................................... 63 3.3. Results ................................................................................................ 64 3.3.1. Quantification of essential amino acids .............................................. 64 3.3.2. Comparison of essential amino acids between commercial breadfruit and other staples ................................................................ 67 3.4. Discussion .......................................................................................... 72 3.5. Summary ............................................................................................ 76 Chapter 4. Breadfruit Protein Digestibility Analysis Using an In Vitro Human Digestion Model ................................................................... 77 4.1. Synopsis ............................................................................................. 77 4.1.1. Objectives ............................................................................................ 77 4.2. Materials and Method ......................................................................... 78 4.2.1. Reagents ............................................................................................ 78 4.2.2. Sample preparation: ........................................................................... 79 4.2.3. In vitro digestion model to mimic human digestion ............................. 79 4.2.4. Protein determination in the flours and digestion extracts .................. 81 4.3. Results ................................................................................................ 83 4.4. Discussion .......................................................................................... 84 4.5. Summary ............................................................................................ 85 Chapter 5. Effects of Breadfruit Digestion on Human Colon Epithelial Cells Using an In Vitro Cell Model ................................................... 86 5.1. Synopsis ............................................................................................. 86 5.1.1. Objectives ............................................................................................ 86 5.2. Materials and Method ......................................................................... 87 5.2.1. Reagents ............................................................................................. 87 5.2.2. Caco-2 human epithelial colorectal adenocarcinoma cells ................. 88 x 5.2.3. Digestion extracts preparation ............................................................. 89 5.2.4. Effects of digestion extracts on Caco-2 cell viability ........................... 90 5.2.5. Effects of LPS and/or IL-1β stimulation on Caco-2 cells ..................... 90 5.2.6. Effects of digestion extracts combined with LPS and/or IL-1β stimulations on Caco-2 cells ............................................................... 92 5.2.7. Primers design and efficiency testing .................................................. 93 5.2.8. Statistical analysis .............................................................................. 95 5.3. Results ................................................................................................ 95 5.3.1. Effects of digestion extracts on Caco-2 cell viability ........................... 95 5.3.2. Effects of LPS and/or IL-1β stimulations on Caco-2 cells ................... 99 5.3.3. Effects of digestion extracts combined with LPS and/or IL-1β stimulations on Caco-2 cells ............................................................. 104 5.4. Discussion ........................................................................................ 123 5.4.1. Cytotoxicity of wheat and breadfruit digestion to Caco-2 cells .......... 123 5.4.2. Cytokine response of breadfruit- and wheat-treated Caco-2 cells .... 123 5.5. Summary .......................................................................................... 126 Chapter 6. Effect of the Breadfruit Diet on Mice Health ................................. 127 6.1. Synopsis ........................................................................................... 127 6.1.1. Objectives .......................................................................................... 128 6.2. Methods ............................................................................................ 128 6.2.1. Reagents .......................................................................................... 128 6.2.2. Diet design ....................................................................................... 129 6.2.3. Experimental animals ....................................................................... 134 6.2.4. Overall growth evaluation and hematology analysis ......................... 135 6.2.5. Tissue collection ............................................................................... 135 6.2.6. Feces protein, total mineral analysis, and fecal occult blood xi detection ........................................................................................... 136 6.2.7. Ileum morphology examination .......................................................... 136 6.2.8. Major cytokine response on ileum .................................................... 137 6.2.9. Quantification of bacterial groups in the colon .................................. 138 6.2.10. Statistical analysis ........................................................................... 138 6.3. Results .............................................................................................. 139 6.3.1. Overall health and growth ................................................................. 139 6.3.2. Hematology analysis ........................................................................ 146 6.3.3. Fecal protein, total mineral analysis, and fecal blood detection ........ 149 6.3.4. Ileum morphology examination ......................................................... 153 6.3.5. Major cytokine response on ileum .................................................... 158 6.3.6. Quantification of bacterial groups in the colon ................................... 161 6.4. Discussion ........................................................................................ 164 6.4.1. Overall heath and growth ................................................................. 164 6.4.2. Intestinal health evaluation ............................................................... 167 6.5. Summary .......................................................................................... 169 Chapter 7. Conclusion ...................................................................................... 170 References ........................................................................................................... 174 Appendices .......................................................................................................... 194 Appendices A: Breadfruit field data sheet in Kauai ......................................... 194 Appendices B: JR lab reports of the diets used in the mice study ............... 1945 xii List of Tables Table 1-1 Common dishes made from breadfruit in different areas ........................... 2 Table 1-2 Breadfruit production in 2007 Agricultural Censuses Report Conducted by the U.S. Department of Agriculture .................................... 4 Table 1-3 The classification of Breadfruit (Artocarpus altilis and Artocarpus altilis× A. mariannensis) ............................................................................ 6 Table 1-4 Summary of Literature Search Using Web of ScienceTM and Google ScholarTM .................................................................................................. 8 Table 1-5 The minimum and maximum reported values for breadfruit (Artocarpus altilis and A. altilis× A. mariannensis) proximate analyses .................................................................................................. 12 Table 1-6 The minimum and maximum starch and sugar contents of breadfruit (Artocarpus altilis and A. altilis× A. mariannensis) .................................. 15 Table 1-7 The minimum and maximum carotenoid and vitamin content for breadfruit (Artocarpus altilis and A. altilis× A. mariannensis) .................. 17 Table 1-8 Reported minimum and maximum mineral content for breadfruit (Artocarpus altilis and A. altilis× A. mariannensis) .................................. 19 Table 1-9 Percent daily of recommended daily intake of essential nutrients provided by consumption of breadfruit .................................................... 20 Table 1-10 Reported maximum and minimum anti-nutrients for breadfruit (Artocarpus altilis and A. altilis × A. mariannensis). ................................ 23 Table 2-1 The protocol for the collection of seasonality data for breadfruit accessions by visual estimates ............................................................... 28 Table 2-2 The number of months between planting and fruit production for Artocarpus species and cultivars grown in the McBryde Garden, Kauai ....................................................................................................... 30 Table 2-3 The summary of the total fruit number, average fruit weight, and yield xiii in Artocarpus species after being planted 4 years and 7 years. Different plant number exists due to the difference in plant age ............. 43 Table 2-4 Comparison of fruit growth between Rotuma and Ma’afala in Kauai and New Caledonia (Lebegin et al., 2007) .............................................. 50 Table 2-5 Comparison of the environmental and climate factors for breadfruit plantings in Kauai and Maui, Hawaii, and New Caledonia ...................... 51 Table 2-6 Comparison of Artocarpus camansi (breadnut) production in McBryde Garden in Kauai with the University of the West Indies Field Station in Valsayn, Trinidad, and Tobago (Roberts-Nkrumah 2005) ....................................................................................................... 53 Table 2-7 Comparison of the protein yields between Ma’afala and other staples .... 55 Table 3-1 The cultivar list of breadfruit (Artocarpus altilis and A. altilis × A. mariannesis) used in the amino acid analysis ......................................... 59 Table 3-2 HPLC gradient elution for the breadfruit amino acid study ....................... 63 Table 3-3 The summary of amino acid content in commercially available breadfruit cultivars (Artocarpus altilis and A. altilis x A. mariannensis): Ma’afala, Yellow, White, Piipiia, Puaa, and Ulu fiti .......... 68 Table 3-4 Nutritional value of commercially available breadfruit cultivars (Artocarpus altilis and A. altilis × A. mariannesis): Ma’afala, Yellow, White, Piipiia, Puaa, and Ulu fiti .............................................................. 75 Table 4-1 Composition of saliva, gastric solution, duodenal solution, and bile solution used in the multi-stage enzymedigestion model ........................ 81 Table 5-1 Experimental design for testing effects of digestion extracts combined with LPS and/or IL1 beta stimulation on Caco-2 cells (n=3) after 24 hours ................................................................................ 93 Table 5-2 RNA sequence, best annealing temperature and primer efficiency for the primers used in the breadfruit in vitro study ...................................... 94 Table 5-3 Cytokine response of Caco-2 after 24 hours of breadfruit/wheat xiv digestion treatments under various stimulations ................................... 106 Table 6-1 Comparison of nutritional value between the breadfruit (BF) diet and 5LG4 diet .............................................................................................. 129 Table 6-2 Comparison of average body composition and tissue weight between the BF-fed (breadfruit-fed) mice and 5LG4-fed mice ............................. 143 Table 6-3 Comparison of blood hematology between mice fed on the breadfruit (BF) diet and 5LG4 diet ......................................................................... 147 Table 6-4 Histological examination of ileum morphology ....................................... 154 xv List of Figures Figure 1-1 The summary of literature cited describing breadfruit (Artocarpus altilis and A. altilis ×A. mariannensis) nutritional Composition. a) Proximate analysis, b) carotenoid and vitamin analysis, c) mineral analysis ................................................................................................... 14 Figure 2-1 Average fruit number per tree of breadfruit cultivars planted from 2008 to 2012 (a). Average fruit number per month of Artocarpus altilis (n=10), A. camansi (n=4), A. mariannensis (n=1), and A. altilis × A. mariannensis (n=10) from 2008 to 2012 (b) .................................... 34 Figure 2-2 The average percentage of years (a) and average percentage of breadfruit trees (b) that breadfruit trees bore fruit, edible fruit and male flowers from 2007 to 2012 in National Tropical Botanical Garden in Kauai, Hawaii edible/harvestable fruit refers to full-sized fruit, mature fruit, and ripe fruit. ............................................................... 35 Figure 2-3 Comparison of individual edible fruit seasonality profiles of breadfruit cultivars planted in the National Tropical Botanical Garden in Kauai and Maui, Hawaii. ................................................................................... 38 Figure 2-4 Comparison of individual male flower seasonality profiles of breadfruit cultivars planted in the National Tropical Botanical Garden in Kauai and Maui, Hawaii ....................................................................... 40 Figure 2-5 Average fruit number per year of breadfruit cultivars planted in the National Tropical Botanical Garden in Kauai, Hawaii from 2 years to 8 years old. ............................................................................................. 42 Figure 2-6 Average fruit weight for breadfruit cultivars from 2 years old to 8 years old. ................................................................................................ 45 Figure 2-7 Yield for breadfruit cultivars from 2 years to 8 years old. ........................ 46 xvi Figure 2-8 Total fruit number (a), and average fruit weight (b) for breadfruit cultivar Ma’afala in the National Tropical Botanical Garden at on Kauai. ...................................................................................................... 47 Figure 3-1 Breadfruit (Artocarpus altilis) and hybrids (A. altilis × A. mariannensis) essential amino acid content (mg/g protein). ................... 65 Figure 3-2 Comparison of essential amino acid content between breadfruit (Artocarpus altilis) and hybrids (A. altilis × A. mariannensis) based on protein weight (a) and dry tissue weight (b) ....................................... 66 Figure 3-3 Comparison of essential amino acid content between commercially available breadfruit cultivars (Artocarpus altilis and A. altilis x A. mariannensis): Ma’afala, Yellow, White, Piipiia, Puaa, and Ulu fiti and other staples based on protein weight. ............................................. 71 Figure 3-4 Comparison of essential amino acid content between commercially available breadfruit cultivars (Artocarpus altilis and A. altilis x A. mariannensis): Ma’afala, Yellow, White, Piipiia, Puaa, and Ulu fiti and other tropical staples based on fresh tissue weight. ......................... 72 Figure 4-1 A Schematic representation of the in vitro digestion model .................... 80 Figure 4-2 Protein content in wheat and breadfruit flour before and after digestion (a) and digestion extracts (b) by BCA and Modified Lowry Assays (n=3). .......................................................................................... 84 Figure 5-1 Effects of digestion extracts of wheat and breadfruit on cell viability. a) 1% digestion extracts. b) 5% digestion extracts. c) 10% digestion extract. d) 50 % digestion extracts. ......................................................... 98 Figure 5-2 Estimated total number of Caco-2 cells per ml after treatment with digestion extracts for 4 hrs. ..................................................................... 99 xvii Figure 5-3 The mRNA expression of cytokines from Caco-2 cells with no stimulation, IL-1β, or LPS+IL-1β stimulation for 4 hrs, 8 hrs, and 24 hrs. (a) MCP-1. (b) iNOS. (c) TNF-α. (d) IL-4. (e) IL-6. (f) IL-8. (g) IL-10. (h) IFN-γ. ......................................................................................... 104 Figure 5-4 Effect of digestive enzyme solution, wheat digestion, and breadfruit digestion on cytokine expression in Caco-2 cells without LPS or IL-1β stimulation for 24 hours. a) IL-4, b) IL 10, c) iNOS, d) TNF-α, e) IFN-γ, f) IL-8,g) IL- 6, h) MCP-1. ........................................................... 110 Figure 5-5 Effect of digestive enzyme solution, wheat digestion, and breadfruit digestion on cytokine expression in Caco-2 cells stimulated with LPS (1000 ng/mL) for 24 hours. a) IL-4, b) IL 10, c) TNF-α, d) IFN-γ, e) MCP-1, f) IL-8, g) IL- 6 h) iNOS. ........................................................... 114 Figure 5-6 Effect of digestions on cytokine expression on Caco-2 cells stimulated with IL-1β (100 ng/mL) for 24 hours a) IL-4, b) IL 10, c) iNOS, d) TNF-α, e) IFN-γ, f) MCP-1, g) IL-8, h) IL- 6. ........................... 118 Figure 5-7 Effect of digestive enzyme solution, wheat digestion and breadfruit digestion on cytokine mRNA expression in Caco-2 cells stimulated with LPS (1000ng/mL) and IL-1β(100 ng/mL) for 24 hours. a) IL-4, b) IL 10, c) iNOS, d) TNF-α, e) IFN-γ, f) MCP-1, g) IL-8, h) IL- 6. ............. 122 Figure 6-1 Comparison of scavenging activity percentage at 15 minutes between breadfruit diet and 5LG4 diet using DPPH methods. .............. 134 Figure 6-2 Comparison of daily body weight (a) and growth rate (b) of mice fed on breadfruit (BF) and 5LG4 diets. ........................................................ 140 Figure 6-3 Comparison of food usage of mice fed on the breadfruit (BF) and 5LG4 diets ............................................................................................. 141 Figure 6-4 Comparison of daily water consumption (a) and average daily water xviii consumption (b) of mice fed on breadfruit (BF) and 5LG4 diets. ........... 142 Figure 6-5 Comparison of fecal protein content from mice fed with the breadfruit (BF) and 5LG4 diets at Day 4 (a), Day 7 (b), Day 14 (c), and Day 21 (d) ...................................................................................... 151 Figure 6-6 Comparison of total mineral content from mice fed with the breadfruit (BF) and 5LG4 diets at Day 4 (a), Day 7 (b), Day 14 (c), and Day 21 (d) ...................................................................................... 153 Figure 6-7 Representative histopathology of the ileum of 5LG4-fed male mice (a), BF-fed male mice (b), 5LG4-fed female mice (c), and BF-fed female mice (d) at 3 weeks of age stained with haematoxylin and eosin (H&E). .......................................................................................... 157 Figure 6-8 Comparison of cytokine expression between ileums of breadfruit (BF)-and 5LG4-fed mice, a) TNF-α, b) IFN-γ, c) IL-10, d) IL-6, e) iNOS ..................................................................................................... 160 Figure 6-9 Comparison of bacteria expression between ileums of breadfruit diet and 5LG4 diet fed mice, a) Bacterioidetes, b) Firmicutes, c) Bifidobacterium spp., d) Lactobacillus spp., e) Enterobacteriacae ........ 163 xix List of Symbols and Abbreviations Ala Alanine Arg Arginine Asn Asparagine Asp Aspartic acid BF Breadfruit BCA Bicinchoninic acid BSA Bovine serum albumin Caco-2 cells Human epithelial colorectal adenocarcinoma cells Glu Glutamic acid Gly Gluycine His Histidine H&E staining Haematoxylin and eosin staining HPLC High performance liquid chromatography IFN γ Interferon gamma IL 1β Interleukin 1 beta IL Interleukin Ile Isoleucine iNOS Inducible nitric oxide synthase Leu Leucine LPS Lipopolysaccharide Lys Lysine MCH Mean corpuscular hemoglobin xx MCHC Mean corpuscular hemoglobin concentration MCP-1 Monocyte chemoattractant protein-1 MCV Mean corpuscular volume Met Methionine MPV Mean platelet volume Phe Phenylalanine Pro Proline RDW Red cell distribution width RT-qPCR Real time quantitative polymerase chain reaction Ser Serine Thr Threonine TNF-α Tumor necrosis factor alpha Trp Tryptophan Tyr Tyrosine Val Valine xxi Acknowledgements I would like to take this opportunity to thank everyone that supported and helped me during my graduate studies. First and foremost, I would like to thank my advisors, Dr. Susan Murch and Dr. Deanna Gibson. Dr. Murch provided the opportunities and environment for the growth of this project. I thank her for always being supportive, wise, and understanding. I thank her for being there for me whenever I need, giving me hope and courage, and making it all possible. She is also a great cook and her food always cheers me up (Yummy!). I also want to express my sincere thanks to Dr. Gibson for providing guidance and necessary training for the project development. I am also indebted to the rest of my advisory committee, Dr. Miranda Hart, Dr. Frederic Menard and Dr. Paula Brown, for their continued support and advice throughout the graduate program. Thank you to Dr. Diane Ragone for sharing the breadfruit germplasm collection at the National Tropical Botanical Garden. I would like to acknowledge the contribution of Dr. Paul Shipley, who generously served as part of my comprehensive exam. I also want to thank Dr. Max Jones, who collected the breadfruit samples used in this project and provided guidance in data analysis. It is important to give my gratitude to other people at the University of British Columbia for all the assistance and company they provided during this graduate program. This project would be impossible without the help from everyone in the Murch and Gibson labs. My deepest gratitude goes to Dr. Christina Turi, Broc Glover, Katie Axwik, Tiah Lee, Daniella DeCoffe, Sandeep Gill, and Nishat Tasnim for their assistance in conducting the project and/or analyzing the data. While there xxii are too many names to include here, I also want to thank Alex Lane, Christina Livingston, and Kathy Baker for providing an efficient lab environment. I want to thank the Center for Scholarly Communication, especially Lori Walter, Amanda Brobbel, and Ellen Campbell, for their time and support. Additionally, I would like to acknowledge the contribution of the Trustees and Fellows of the National Tropical Botanical Garden and the Breadfruit Institute. Na Lima Kokua volunteers were crucial to the success of this project. In particular, I would like to acknowledge Billie Dawson who led a team of volunteers including: Loren Johnson, Joyce Packard, Linda Spade, Noreen Daniels, Mary Stone, Neil Brosnahan, and Cherisse Kent. Finally, I would like to thank my parents and friends for their patience and support over these years. I thank my parents for encouraging me and helping me in whichever way they could. Thank you to my friends, Alessandro Errico, Christ Heckel, and Edward Regier for listening to my frustrations and giving me food and candies when I was down. A special thank you must be given to my husband and colleague, Jensen Lund, for making my life much easier and giving me immeasurable help in the lab. Thank you for all the dishes and proofreading you did for me. xxiii Dedication I dedicate this work to my parents, who love me more than anything else in the world. 献给我的父亲刘柏生,母亲王月桂. 1 Chapter 1. Introduction 1.1. History of breadfruit consumption The history of human consumption of breadfruit as a staple crop of the Pacific extends at least 3,000 years. Traditionally cultivated varieties were bred by individuals, families, and communities and carried by the Lapita from Papua New Guinea throughout Oceania (Ragone, 1997). The traditional cultivars of breadfruit in Hawaii were brought with the Lapita to Hawaii sometime between 1000 and 1200 A.D. European collections of breadfruit began with the Spanish and the Dutch East India Company during the 17th century. In the late 1800s, several governments and individuals engaged in the widespread dissemination of breadfruit to regions outside of Oceania (Barrau, 1976; Ragone, 1997; Smith et al., 1992). In 1769, Joseph Banks traveling with Captain James Cook to Tahiti recognized the potential of breadfruit and observed the following (Banks, 1962): “In the article of food these happy people may almost be said to be exempt from the curse of our forefather; scarcely can it be said that they earn their bread with the sweat of their brow when their cheifest sustenance Bread fruit is procurd with no more trouble than that of climbing a tree and pulling it down. Not that the trees grow here spontaneously but if a man should in the course of his life time plant 10 such trees, which if well done might take the labor of an hour or thereabouts, he would as compleatly fulfull his duty to his own as well as future generations as we natives of less temperate climates can do by toiling in the cold of winter to sew and in the heat of summer to reap the annual produce of our soil, which when once gatherd into the barn must be again resowd and re-reapd as often as the Colds of winter or the heats of Summer return to make such labor disagreable.” (The Endeavour Journal of Joseph Banks, August 14th 1769) 2 In August 1787, Banks successfully persuaded King George III to invest in an expedition to collect breadfruit and transplant it to the Caribbean as a reliable food source for sugar plantations. Responsibility for the expedition was placed under the leadership of Lieutenant William Bligh RN and the HMS Bounty sailed from England in December 1787. The crew of the Bounty collected 1,015 breadfruit trees but all were lost in the famous mutiny at sea in 1789. Determined to transport breadfruit from East to West, Sir Joseph Banks ordered Bligh to commence two additional voyages that successfully transplanted 668 breadfruit trees from Tahiti to Jamaica and St. Vincent in 1793 and 1796 (Powell, 1977). Breadfruit is commonly used as a staple food in Polynesia and Micronesia, and as a supplementary staple in most of Melanesia (Fosberg, 1960; Lim, 2012; Ragone and Raynor, 2009). Edible portions of breadfruit for human consumption include immature and ripe fruit, seeds, young leaves, and ripe blossoms. Breadfruit is consumed raw, boiled, roasted, baked, or fried. Preservation of the fruit can be achieved through sun-drying or in pits (Jones et al., 2013a; Lim, 2012; Ragone and Raynor, 2009). Breadfruit is consumed in various ways in the tropical regions (Lim, 2012; Morton, 1987; Meilleur et al., 2004; Ragone and Raynor, 2009) (Table 1-1). Table 1-1 Common dishes made from breadfruit in different areas (Lim, 2012; Morton, 1987; Meilleur et al., 2004; Ragone and Raynor, 2009) Region Common dishes made from breadfruit Bahamas Breadfruit soup made from under-ripe fruit Barbados Breadfruit chips made from overripe or soft fruit Combined with wheat for bread making 3 Region Common dishes made from breadfruit Brazil Combined with wheat for bread making Sir Lanka Breadfruit dipped in a salt solution Dominican Republic Breadfruit bread "buen pan" Philippines Cooked fruit in coconut and sugar Grenada “oil down” by cooking breadfruit, meat, coconut milk, and dasheen leaves Guam Breadfruit paste soaked in water Hawaii Boiled under-ripe fruits with butter and sugar, or salt and pepper Breadfruit chowder made from cooking breadfruit with vegetables, bacon, and milk Substitution for taro in poi, "poi ulu" Jamaica Breadfruit flour-based porridge Malaysia Fried sliced firm-ripe breadfruit in syrup or palm sugar Micronesia Made into a paste by fermenting breadfruit in banana leaf-lined boxes Breadfruit soaked and beaten in the sea New Hebrides Fermented breadfruit Polynesia Fermented or baked breadfruit in a native oven Puerto Rico "pana" or "panen," cooked breadfruit with olive oil, onions, and saturated bacalao (salted cod fish) Samoa “masi,” fermented breadfruit with banana and Heliconia leaves to make a paste, which is cooked with coconut cream Solomon Islands Fruit roasted in an underground oven (imu) Trinidad Breadfruit chips made from overripe or soft fruit “oil down,” cooked breadfruit, meat, coconut milk and dasheen leaves Tobago “oil down,” cooked breadfruit, meat, coconut milk and dasheen leaves 4 1.2. Current uses and significance of breadfruit in the world Breadfruit is one of 35 crop species identified in the International Treaty on Plant Genetic Resources for Food and Agriculture as an underutilized crop with the potential to improve food security and interdependence (FAO, 2009). The reported number of breadfruit farms in the United States were around 5000 in 2007 (USDA, 2007) (Table 1-2). Table 1-2 Breadfruit production in 2007 Agricultural Censuses Report Conducted by the U.S. Department of Agriculture (USDA, 2007) Regions Virgin Islands Northern Mariana Islands Guam Island American Samoa Year 2007 2007 2007 2008 Number of farms 54 42 14 4,828 Number of non-bearing trees 35 46 61 NA Number of bearing trees 280 216 258 NA Pounds harvested for sale 10,713 4,774 9,650 252,375 Pounds harvested for consumption NA NA NA 3,140,728 In the past, breadfruit was mainly produced in Hawaii, Puerto Rico, the Marianas Islands and American Samoa for local use and the commercialization of breadfruit was impossible due to difficulties in propagation (Murch et al., 2008; Ragone and Raynor, 2009). In 2008, we reported the development of in vitro propagation methods 5 for clonal propagation of breadfruit trees in a sterile, controlled environment (Murch et al., 2008; Shi et al., 2007). This advancement leads to the development of a horticultural industry for mass propagation and distribution of the trees to tropical countries in projects designed to increase food security (www.globalbreadfruit.com). 1.3. Breadfruit botanical description The common name ‘breadfruit’ refers to A. altilis, which can be triploid (2n=3x=~84) and producing no seeds or diploid (2n=2x=~56) and producing few to several seeds (Ragone, 2001). Some of the cultivated varieties of breadfruit are interspecific hybrids of A. altilis × A. mariannensis (Fosberg, 1960; Zerega et al., 2004, 2005) (Table 1-3; USDA, 2015a; Stevens, 2012). Early generation hybrids produce fruits that most closely resemble its A. mariannensis parent while later generation hybrids more closely resemble A. altilis and are seedless (Jones et al., 2013 a). Several thousand cultivated varieties of breadfruit are known across the Pacific tropical islands and the fruit has been used as a staple food source for about 3,000 years. Breadfruit is a moderately large evergreen tree generally growing 15 to 20 m, but sometimes reaching over 30 m tall (Niering, 1963; Ragone, 1997; 2006). Breadfruit trees are monoecious, with both male and female inflorescences in the same tree. The inflorescences are comprised of about 1500-2000 individual florets connected to the receptacle (Ragone 1997; 2006). 6 Table 1-3 The classification of breadfruit (Artocarpus altilis and Artocarpus altilis× A. mariannensis) Rank Scientific name and common name Kingdom Plantae – Plants Subkingdom Embryophyta Unranked Angiosperms Unranked Eudicot Unranked Rosids Order Rosales Family Moraceae – Mulberry family Genus Artocarpus J.R. Forst. & G. Forst. – Breadfruit Species Artocarpus altilis (Parkinson) Fosberg – Breadfruit Artocarpus mariannensis Trécul– Artocarpus The shape of the fruit is irregular, but the texture is generally flattened or rounded pebble. The advanced hybrids have a similar texture and shape to the early generation hybrids, but the size of the fruit is relatively larger and the fruit is seedless (Jones et al., 2013a). The general fruit size is 12 cm×16 cm and the fruit weight ranges from 1 to 2 kg. Some cultivars can produce fruit weighing up to 6 kg (Ragone, 1997, 2006; Zerega et al., 2005). During the maturation process, the outside fruit skin turns from light green to yellow and the inside flesh becomes creamy white to yellow. 1.4. Current breadfruit nutritional analysis Using Web of Science, Google Scholar search engines, and government databases and regional reports between July and Oct. 2014, I identified 41 reports researching on the nutritional profile of breadfruit cultivars (Table 1-4). Proximate data 7 for breadfruit included protein, total carbohydrate, crude fiber, starch, and lipid content as well as total calories, insoluble and soluble fiber content (Figure 1-1a). Studies by Golden and Williams (2001), Holloway et al. (1985), Jones et al. (2011a&b), Ragone and Cavaletto (2006), Tumaalii and Wootton (1988), and Wootton and Tumalii (1984) included cultivar name and variability between cultivars with respect to protein, carbohydrate and caloric content (Table 1-4). Overall, the literature describes a wide range of values. For example, lipid contents varied between reports (0.08 - 4.90 g per 100g of fresh or cooked breadfruit), but most studies of fats generally reported values of less than 2 g per 100 g (Table 1-5). Fiber content varied widely from 0.90–4.88 g/100g fresh weight, 2.13-7.37 g/ 100g cooked weight, and 1.66 –15.29 g/100g in flour (Table 1-5). Ragone and Cavaletto (2006) found no significant difference in fiber content of different cultivars. It is difficult to assess the total fiber content of generic breadfruit since some of the variability may be due to different methods for determination of fiber and criteria for fiber definitions that have been revised over the years to include various types of carbohydrates such as cellulose, hemicelluloses, pectins, hydrocolloids, beta-glucans, resistant starch, and non-digestible oligosaccharides (McClearly et al., 2012; Mudgil and Barak, 2013). Furthermore, the fiber content of flours made from selected breadfruit tissues, i.e. peel, core, or pulp, was found to significantly differ (Graham and Negron de Bravo, 1981; Mayaki et al., 2003). 8 Table 1-4 Summary of Literature Search Using Web of ScienceTM and Google ScholarTM Source Species1 Cultivar Number Preparation Method Adegunwa et al. 2014 Aa Instant breadfruit flour Adeniran et al. 2012 Aa Fermented flour Amusa et al. 2002 Ac a Fresh fruit that was picked after immediately dropping from trees Appiah et al. 2011 Aa Firm and mature fruit made into fermented or unfermented pulp flour Aregheore 2000 Aa Flour Bahado-Singh et al. 2006 Aa, Aa × Am Fresh, boiled or baked fruit collected at the mature stage Englberger et al. 2003a Am, Aa 8 Raw or boiled fruit collected at the ripe mature stage (creamy to white flesh), and sampled with or without rind Englberger et al. 2003b Am, Aa 10 Raw, baked or boiled fruit collected at the mature or ripe stage Englberger et al. 2007 Am, Aa 16 Fresh, boiled or dried fruit, picked when flesh was yellow, brown, or cream coloured. Englberger et al. 2014 Aa, Am 7 Raw, fruit collected at mature or ripe stage, with and without skin 9 Source Species1 Cultivar Number Preparation Method Esuoso and Bamiro 1995 Aa Breadfruit flour Graham and Negron de Bravo 1981 Aca Breadfruit flour Golden and Williams 2001 Aa 1 Fresh fruit Holloway et al. 1985 Aa 1 Fresh fruit suitable for consumption Haydersah et al. 2012 Ac a Flour Huang et al. 2000 Aa (?) Fresh fruit collected when still firm and not overripe Ijarotimi and Aroge 2005 Aa Flour made from freshly harvested fruit Jones et al. 2011a Aa, Am, Aa × Am 94 Raw fruit collected at mature stage, not fully ripe; Flour Jones et al. 2013a Aa, Am, Aa × Am, 94 Raw, baked, or boiled fruit collected at mature stage, not fully ripe. Leterme et al. 2005 Ac a Fresh fruit Loos et al. 1981 Ac Starch isolate / flour Malomo et al. 2011 Aa, A. integrifolia, Flour made from freshly harvested mature breadfruit and breadnut Mayaki et al. 2003 Ac a Fruit harvested at mature but unripe stage and made 10 Source Species1 Cultivar Number Preparation Method into a flour Nelson-Quartey et al. 2007 Aa Flour made from mature, firm fruit Nochera and Caldwell 1992 Ac a Breadfruit flour Nwokocha and Williams 2010 Aa Starch isolate Oduro et al. 2007a Aa Flour made from mature unripe fruit Oduro et al. 2007b Aa Flour made from mature unripe fruit Oladunjoye et al. 2010 Aa Breadfruit meal Oladunjoye and Ojebiyi 2011 Aa Breadfruit meal Oso et al. 2010 Aa Sun dried breadfruit meal Oulaï et al. 2013 Aa Flour Ragone and Cavaletto 2006 Aa, Aa × Am 20 Boiled fruit that were collected at the mature, unripe stage. Ravindran and Sivakanesan 2006 Ac a Breadfruit meal Reeve 1974 Aa Fresh dehydrated fruit 11 Source Species1 Cultivar Number Preparation Method Samuda et al. 1998 Aa Boiled (immature green colour) and roasted (mature, yellow-brown colour) fruit Tumaalii and Wootton 1988 Aa 7 Starch isolate Wang et al. 2011 Aa Defatted flour Wenkam, 1990 Ac a Cooked or raw breadfruit that was collected at the ripe or green stage. Widanagamage et al. 2009 Aa/Ac a Boiled breadfruit Wootton and Tumaalii, 1984 Aa 7 Breadfruit Flour made from immature, mature or very mature fruits. 1Aa = Artocarpus altilis; Ac = Artocarpus communis; Am = Artocarpus mariannensis; Aa × Am = Artocarpus altilis × Artocarpus mariannensis ? Indicates that the species name is not entirely clear a A. communis is a synonym for A. altilis 12 Table 1-5 The minimum and maximum reported values for breadfruit (Artocarpus altilis and A. altilis× A. mariannensis) proximate analyses Nutrient Fresh (100g) Cooked (100g) Flour (100g) Min Max Min Max Min Max Ash (%) 0.8 4.6 NA NA 0.8 6.7 Moisture (%) 19 83 53.2 83.6 2.5 21 Dry matter (%) 17 80.9 16.4 46.8 79 97.5 Energy (Kcal) 102 310 80 160.9 279.8 378 Total Carbohydrates (g) 14.3 70.1 18.1 37 50 88 Lipid (g) 0.1 4.5 0.1 4.9 0.5 11.8 Protein (g) 0.07 5.2 0.6 11.4 1.9 18.7 Crude Fiber (g) 0.9 4.9 1.8 7.4 0.8 15.3 Insoluble Fiber (g) 3.1* 25.6* 2.4 20 7.5* 62.3* Soluble Fiber (g) 0.20 0.2 NA 7.2 0.2* 11.4* * Values marked with * were extrapolated based on the calculated average dry weight for breadfruit (fresh = 37.55%, baked = 29.35%, flour = 91.40%). A value of NA indicates that a specific group was either not detected or below the limits of quantification. 13 Figure 1-1 a Figure 1-1 b 05101520253035Number of publicationsFresh Cooked Flour02468101214161820B Ca Cl Co Cu Fe K Mg Mn Na Ni P S ZnNumber of publicationsFresh Cooked Flour 14 Figure 1-1 c Figure 1-1 The summary of literature cited describing breadfruit (Artocarpus altilis and A. altilis ×A. mariannensis) nutritional composition. a) Proximate analysis, b) carotenoid and vitamin analysis, c) mineral analysis 1.4.1. Carbohydrates Loos et al. (1981) were the first researchers to focus on the characterization of starch from breadfruit. Their work explored basic physicochemical and structural properties of breadfruit starch, but, the study did not identify the cultivars used. In 1984 and 1988, Wootton and Tumaalii published similar research on starch isolates from breadfruit with clear identification and comparison between cultivars. In general, breadfruit starch has an amylose content ranging from 16.6% to 20.4% and a granular size from 0.5 µm to 37.8 µm (Wootton and Tumaalii, 1984). Breadfruit starch composition changes with the maturity of the fruit, with sugars released from the 024681012Number of publicationsFresh Cooked Flour 15 starches as the fruit matures (Graham and Negron de Bravo, 1981). This difference in nutrient composition with maturity also contributes to reported variation in carbohydrate and sugar content (Golden and Williams, 2001; Graham and Negron de Bravo 1981; Wootton and Tumaalii, 1984; Table 1-6), which increases the difficulty of cross comparison between studies. Glucose and sucrose were found to be the dominant sugar in fully mature breadfruit across the 8 cultivars studied (Golden and Williams, 2001; Wootton and Tumaalii 1984). When compared to other staple foods such as corn, sweet potatoes, yam and wheat (Esuoso and Bamiro, 1995; Nwokocha and Williams, 2010), the starch properties of breadfruit are suitable for a range of diets and applications (Adebowale et al., 2004; Haydersah et al., 2012). Table 1-6 The minimum and maximum starch and sugar contents of breadfruit (Artocarpus altilis and A. altilis× A. mariannensis) Nutrient Fresh (g/100g) Cooked (g/100g) Flour (g/100g) Min Max Min Max Min Max Total Starch 15.5 28.4 NA NA 42.6 75.7 Fructose NA 0.16 NA NA 4.3 13.6 Glucose 0.18 0.44 NA NA 6.5 11.3 Sucrose 0.25 0.62 NA NA NA 16.4 Total Sugars NA NA NA NA 2.8 26.8 Total Reducing Sugars NA NA NA NA 2.7 22.5 * Values marked with * were extrapolated based on the calculated average dry weight for breadfruit (fresh = 37.55%, baked = 29.35%, flour = 91.40%). A value of NA indicates that a specific group was either not detected or below the limits of quantification. 16 1.4.2. Carotenoids Quantification of carotenoids included seven nutrients: alpha carotene, beta carotene, beta cryptoxanthin, lutein, lycopene, zeaxanthin and total carotenoids (Figure 1-1b). For carotenoid analysis, all references included species and cultivar names (Table 1-4). Both Englberger et al. (2003 a&b) and Jones et al. (2013b) observed changes in the carotenoid content of breadfruit as a result of cooking, baking or boiling. In addition to the mode of preparation, cultivar or varietal type, tissue sampled (i.e. with rind or without rind), and stage of maturity (starchy mature vs. ripe) have all been found to impact the quantified carotenoids (Englberger et al., 2014, 2003a&b, Jones et al., 2013b; Ragone and Cavaletto, 2006). It is also important to note that the presence or absence of specific carotenoids were either undetected or below the limits of quantification for several cultivars in these studies. Overall, carotenoid content varied widely in our review of the literature (Table 1-7) and is unlikely to be consistent except in a single orchard planted with clonally propagated trees of a single cultivar with standardized harvest and processing protocols. 17 Table 1-7 The minimum and maximum carotenoid and vitamin content for breadfruit (Artocarpus altilis and A. altilis× A. mariannensis) Nutrient Fresh (100g) Cooked (100g) Flour (100g) Min Max Min Max Min Max Total carotenoids (µg) NA 3769 NA 1260 NA 6549 alpha carotene (µg) NA 260 NA 142 NA 537.5 beta carotene (µg) NA 3410 NA 868 NA 5501.7 beta cryptoxanthin (µg) NA 3.3 NA 10.6 NA 20.5 Lutein (µg) NA 690 NA 759 NA 2021.6 Lycopene (µg) NA 48.7 NA 25.9 NA 99.6 Zeaxanthin (µg) NA 60 NA 70 NA 182 Folic acid (µg) NA 1.3 NA 1.0 NA 3.1 Vitamin B1 (mg) 0.12 0.28 0.09 0.14 0.29 0.6 Vitamin B2 (mg) 0.05 0.1 0.02 0.06 0.16 0.4 Vitamin B3 (mg) 0.84 1.7 0.64 1.4 2.30 4.4 Vitamin C (mg) 16.20 21 1.60 12.1 NA 22.7 * Values marked with * were extrapolated based on the calculated average dry weight for breadfruit (fresh = 37.55%, baked = 29.35%, flour = 91.40%). NA indicates that a specific group was either not detected or below the limits of quantification. 18 1.4.3. Minerals Quantification of minerals in breadfruit was relatively common in the literature; however, a majority of references pertained to flours (Figure 1-1c). Similar to proximate analysis, Jones et al. (2011b) and Ragone and Cavaletto (2006) were the only references that included cultivar names (Table 1-4). Both references report significant differences between cultivars with respect to Cu, Fe, K, Mg, Mn, and Zn concentrations. Furthermore, Graham and Negron de Bravo (1981) found that mineral content in breadfruit will differ, not only between tissues types but also between stages of maturity. Consequently, data collected on the mineral nutrition of breadfruit varied considerably (Table 1-8). Comparison of reported values to recommended intake values provided by the FDA indicates that 5.78 ounce (163.86 g) breadfruit flour can provide up to 131% (Ca), 406% (Cu), 109% (Fe), 82% (Mg), 215% (Mn), 315% (P), 133% (K), 41% (Na), and 32% (Zn) of one’s daily mineral requirements (Table 1-9; FDA, 2013). Based on the above, breadfruit is a good source of both magnesium and potassium. Still, it is possible that mineral nutrition of breadfruit is greater than what is currently known, given that no studies have investigated how soil type or environment can influence the overall nutrient content of breadfruit. 19 Table 1-8 Reported minimum and maximum mineral content for breadfruit (Artocarpus altilis and A. altilis× A. mariannensis) Nutrient Fresh (100g) Cooked (100g) Flour (100g) Min Max Min Max Min Max Boron (mg) 0.5 0.5 0.4 0.4 1.3 1.3 Calcium (mg) 18 54 10 30 5 800 Chlorine (mg) NA 2 NA 1.6 NA 4.9 Cobalt (µg) NA 1.1 NA 0.9 NA 2.70 Copper (mg) 0.08 0.3 0.45 0.5 0.1 4.95 Iron (mg) 0.26 52 NA 1.1 0.5 12 Magnesium (mg) 20 70 14 30 9.9 200 Manganese (mg) 0.04 0.3 0.1 0.3 0.1 2. Nickel (mg) NA 0.08 NA 0.06 NA 0.19 Phosphorus (mg) 7 116 18 41 73.7 1920 Potassium (mg) 289 2390 240 522 66.9 2830 Sodium (mg) 3 27 2 70 1.90 597 Sulfur 20 31 15.6 24.2 48.7 75.5 Zinc (mg) 0.09 0.53 NA 0.13 0.13 3 20 Table 1-9 Percent daily of recommended daily intake of essential nutrients provided by consumption of breadfruit Recommended Daily Values Provided by 5.78 Ounce (163.86g) of Breadfruit Nutrient Daily Value Fresh Cooked Flour Min Max Min Max Min Max Energy (Kcal) 2000 8% 25% 7% 13% 23% 31% Total Carbohydrates (g) 300 8% 38% 10% 20% 27% 48% Lipid (g) 65 0% 11% 0% 12% 1% 30% Protein (g) 50 0% 17% 2% 37% 6% 61% Crude Fiber (g) 25 6% 32% 12% 48% 5% 100% Folate 400 0% 0% 0% 0% 0% 1% Vitamin B1 (mg) 1.5 13% 31% 10% 15% 31% 61% Vitamin B2 (mg) 1.7 5% 10% 2% 5% 15% 38% Vitamin B3 (mg) 20 7% 14% 5% 11% 19% 36% Vitamin C (mg) 60 44% 57% 4% 33% 0% 62% Calcium (mg) 1000 3% 9% 2% 5% 1% 131% Copper (mg) 2 7% 20% 37% 37% 8% 406% Iron (mg) 18 2% 473% 0% 10% 5% 109% Magnesium (mg) 400 8% 29% 6% 12% 4% 82% Manganese (mg) 2 3% 27% 7% 25% 6% 215% Phosphorus (mg) 1000 1% 19% 3% 7% 12% 315% Potassium (mg) 3500 14% 112% 11% 24% 3% 133% Sodium (mg) 2400 0% 2% 0% 5% 0% 41% Zinc (mg) 15 1% 6% 0% 1% 1% 32% 1 Percent daily intake values are based on a caloric intake of 2,000 calories, for adults and children four or more years of age as described by the FDA (2013) 21 1.4.4. Vitamins The vitamin content of breadfruit has been reported for folic acid, vitamins B1, B2, B3, and vitamin C (Figure 1-1c). Vitamin C content ranged between 1.6–12.1 mg per 100g of cooked breadfruit for 20 cultivars. In the United States, daily average consumption of refined grains was 5.78 ounce (163.86 g) for male and female over the age of 2 from 2009 to 2010 (USDA, 2015b). According to recommended intake values provided by the FDA, 5.78 ounce serving of breadfruit flour can provide up to 61, 38, 36, and 62 percent of one’s daily requirements for vitamin B1, B2, B3 and C respectively (Table 1-9). A study by Graham and Negron de Bravo (1981) found that the concentration of vitamin C increased from the very immature to mature fruit, but was undetected at the very latest stage of ripening measures, potentially indicating enzymatic conversion of vitamin C at later stages of development. Similar information is needed but has not been generated, for other essential vitamins such as vitamins B5, E, H, and K. 1.4.5. Antinutrients Breadfruit, both raw and cooked, showed limited contents of anti-nutrients summarized in Table 1-10. α-amylase inhibitor was found in breadfruit but trypsin inhibitors was not (Ijarotimi and Aroge, 2005). These inhibitors are antinutrients because they inhibit digestive enzymes but they may also have some beneficial health impacts such as lowering blood glucose, reducing plasma cholesterol and triacylglycerol and treating breast cancer (Slavin et al., 1999). Phenolic antinutrients, including tannins, catechin, gallic acid, and benzoic 22 acid, are commonly found in bran layers of cereal grains, especially the bran layers of the whole grain (Sidhu and Kabir, 2007; Thompson, 1993) and have been found in breadfruit (Appiah et al., 2012; Famurewa et al., 2015; Oulaï et al., 2014 ) (Table 1-10). Phenolic compounds can cause depression in food/feed intake, the formation of less digestible protein complexes, and inhibition of digestive enzymes, but can also prevent damage caused by reactive oxygen species (Slavin, 2004). Breadfruit has maximum total phenolic compounds of 408 mg/100g (Oulaï et al., 2014), which is much lower than whole grain, and similar to wheat germ (349 mg/100g) (Velioglu et al., 1998). Oxalate is the major component of kidney stones in humans. In grain flours, the total oxalate content can range from 37-269 mg/100g, and in nuts, the number increases to 42-469 mg/100g (Chai and Liebman, 2005; Siener et al., 2006). Breadfruit has an oxalate content between 100-192 mg/100g in the flour (Famurewa et al., 2015). The cooking process typically results in a dramatic reduction of oxalate content (Siener et al., 2006). Phytic acid, and its salt phytate can be found in the cotyledon of legumes, oilseeds, and the bran of cereal grains, at a range from 10 to 6000 mg/100g (Sidhu and Kabir 2007; Thompson, 1993). These are considered as anti-nutrients because they can chelate mineral elements in the body, but many researchers have found that phytate can reduce blood glucose, and reduce plasma cholesterol and triacylglycerols (Jenab and Thompson, 2002; Kumar et al., 2010; Schlemmer et al., 2009). The maximum phytate content found in breadfruit is 1269 mg/100g (Famurewa et al., 2015; Oulaï et al., 2014). As with many other anti-nutrients, the 23 cooking process can reduce the phytate content. Cooked breadfruit has a maximum phytate content of 58.33 mg/100g (Oulaï et al., 2014). Other anti-nutrients such as saponin and lectin were not detected in breadfruit flour or cooked breadfruit (Oulaï et al., 2014). Table 1-10 Reported maximum and minimum anti-nutrients for breadfruit (Artocarpus altilis and A. altilis × A. mariannensis). Anti-nutrients Flour (100g) Cooked (100g) Min Max Min Max α-amylase inhibitor activity (AIU) ND 482 118 333 Trypsin inhibitor (TIU) ND ND NA NA Total phenolic compounds (mg) ND 408.73 223.61 321.12 -Tannin (mg) 1 4.3 2.2 4.02 -Catechin (mg) ND 51.07 33.83 40.96 -Gallic acid (mg) ND 102.99 47.02 89.78 -Benzoic acid (mg) ND 66.97 43.15 60.92 Total oxalate (mg) 100 192 NA NA Phytate (mg) 63.4 1269 36.2 58.33 Lignin (mg) 0 4320 3100 4050 ND: Not detected; NA: No data available 24 1.5. Study rationale and objectives There are relatively few nutritional studies on breadfruit in the scientific literature but breadfruit flour is poised to become an international staple food crop in the next decade. The overall hypothesis of this thesis was: “Breadfruit is a good source of protein for human use.” There are a small number of studies on breadfruit protein quantity but breadfruit protein quality was not previously assessed. Likewise the digestion and impacts of breadfruit flour on mammals have not been previously investigated. Therefore, the specific objectives of this study were: 1. To determine the yield of breadfruit per tree and per hectare for 24 cultivars 2. To determine the quality of breadfruit protein by quantifying the essential amino acid content 3. To determine the digestibility of breadfruit flour using an enzymatic model of human digestion 4. To quantify the effects of digested breadfruit flour on human intestinal epithelial cells in an in vitro cell model 5. To quantify whole body responses to consumption of breadfruit flour in a rodent model 6. To make recommendations for the use of breadfruit fruit and flour in human nutrition. 25 Chapter 2. Seasonality, Productivity, and Yield of Breadfruit 2.1. Synopsis Increased commercialization and utilization of breadfruit will require basic research and data to select suitable germplasm and develop optimized production systems adapted to new locations (Jones et al., 2010). The wild seeded progenitor species of breadfruit, breadnut (A. camansi), is propagated by seed. Domesticated breadfruit, both seeded and seedless forms, is traditionally propagated by adventitious root shoots, root cuttings, or air layering. Recently mass propagation of breadfruit has become possible through in vitro micropropagation techniques (Murch et al., 2008; Shi et al., 2007).It is believed that breadfruit is one of the most productive crops in the world with estimated yields of 6 t/ha on a dry weight basis in an orchard production system (Bowers, 1981). However, investigations on breadfruit yield are few in number and even less information is available comparing the yield of different cultivars (Fownes and Raynor, 1993; Lebegin et al., 2007). Additionally, most cultivars are highly seasonal (Fownes and Raynor, 1993; Jones et al., 2010; Morton, 1987), but seasonality studies have been limited to investigations within single locations and it is difficult to predict how they may perform in new regions (Fownes and Raynor, 1993; Lebegin et al., 2007). Since breadfruit is seasonal and highly perishable, unexpected changes in yield and/or seasonality could cause significant economic losses, wasted resources, and disrupt local food supplies. These losses may be mitigated through careful selection of cultivars to extend the season or to help plan for processing fruit into more stable products such as flour, chips, or frozen fruit (Ragone, 2011). 26 2.1.1. Objectives The objective of the study was to investigate and quantify differences in yield, seasonality, and production of protein of breadfruit in a common garden. The study also determined the yield of the breadfruit protein. Each cultivar is represented by only one or two individual trees in the germplasm repository since each tree requires significant space and cultivar conservation is a priority. Therefore, true cultivar-to-cultivar comparisons are not possible and only comparisons of the performance of individuals over 7 years are made. Several factors, including propagation methods, the length of juvenile stage, yield, and fruit weight and size, are investigated to determine the degree of variability and identify suitable germplasm for international distribution. Breadfruit yield and seasonality are compared to previous reports (Jones et al., 2010; Lebegin et al., 2007) that used some of the same genetic materials planted in different locations. 2.2. Materials and methods 2.2.1. Germplasm repository The Breadfruit Institute at the National Tropical Botanical Garden (NTBG) holds the world’s largest curated germplasm collection of breadfruit and its associated relatives including Artocarpus altilis, A. camansi, A. mariannensis, and A. altilis × A. mariannensis hybrids. The collection includes 325 well-documented trees collected from 34 Pacific Islands, the Philippines, Indonesia, Honduras and the Seychelles between 1978 and 2004 (Jones et al., 2011a; 2011b; 2013a). The majority of the trees are conserved in a single 12 acre (4.86 ha) site at Kahanu Garden in Maui 27 (20°47’57.07” N, 156°02’18.42” W) and have been described in detail previously (Jones et al., 2013a). A subset of 26 accessions was established at the NTBG’s McBryde Garden on Kauai, Hawaii (21°88’79.43” N, 159°49’23.15” W). Kauai has a subtropical climate and the major rainy season usually starts in October and ends in April. The McBryde Garden receives rainfall of 939 mm annually with a mean temperature of 24.4 °C, mean maximum temperature of 29.0 °C, and mean minimum temperature of 19.7 °C. The field in land that had been in fallow since it was intensively cultivated with sugarcane until the early 1970s and the soil is compacted from this heavy use. Trees were planted 15 m apart giving a planting density of about 50 trees/ha, irrigated as needed, and mulched and fertilized yearly with a standard N:P:K fertilizer. In 2011, a cover crop of Lablab purpureus was planted beneath the A. camansi trees. Trees were pruned and shaped as they grew beginning with some cultivars in April 2008 and again in November 2011, with the exception of cultivars: White and Rare autia. 2.2.2. Data collection A standard methodology was used for all data collection (Table 2-1). Data were collected weekly from 2006 to 2012. Each tree was divided into four quadrants, and data were collected for each quadrant from southwest to southeast going clockwise around the tree. Using a visual assessment, male flowers and fruit in five stages of development were counted in each quadrant. Mature fruits were then harvested, weighed and measured. Fruits with any disease symptoms were counted, harvested and discard. Aborted fruit on the ground were counted. Total fruit number includes 28 new fruit, less than full-sized fruit, full-sized fruit, mature fruit, and ripe fruit. Edible/harvestable fruit refers to full-sized fruit, mature fruit, and ripe fruit. Plant canopy area, percent leaf area, and plant height were analyzed using the ImageJ 1.47v software (Wayne Rasband, National Institutes of Health, Maryland, USA). Tree circumference was measured at knee height (0.35 m) rather than breast height due to the branching habit of some trees. Table 2-1 The protocol for the collection of seasonality data for breadfruit accessions by visual estimates Category Description Male flowers Inflorescences of any size, small and just emerging from the sheath to full size. New fruit Small fruits that have recently emerged from the leaf sheath; they are often prickly and the stigmas still protrude and remain green. Less than full-sized fruit A wide range of fruit sizes from bigger than the new fruit, 1/2-size, up to almost full-sized. Full-sized fruit Fruits that have reached their maximum size, but have not yet started to mature. Mature fruit Fruits with distinctive characteristics of maturing, such as latex exudate on the skin and slight changes in skin color and texture. Ripe fruit Fruits that are soft and ripe on the tree. Fruits with disease symptoms Fruits with black spots or other disease symptoms evident on the peel. 29 2.3. Results 2.3.1. Time from planting to fruit production Individual germplasm required different time to yield fruit (Table 2-2). Artocarpus altilis grown from root cuttings started to bear fruit after an average of 29 months (Table 2-2) while hybrids (A. altilis × A. mariannensis) took significantly longer with an average of 37 months. Fast fruiting cultivars from root cuttings are Rare autia (23 months), White (25 months), and Meitehid (27 months). Breadnut (A. camansi) trees grown from seeds produced fruit after an average of 39 months with a range from 32 to 57 months. Most of the cultivars produced fruit 4 years after planting (Table 2-2). In vitro-propagated trees of the cultivar, Ma’afala, began fruiting within 23 months (Table 2-2). Since the repository contains only one tree of several varieties, these data are preliminary and more studies are need. 30 Table 2-2 The number of months between planting and fruit production for Artocarpus species and cultivars grown in the McBryde Garden, Kauai NTBG ID Species Cultivar Planted date First fruit appear Month before first fruit Source 000523002 Artocarpus mariannensis Dugdug April-21-04 Sep.-18-07 41 Seed, Mariana Islands 000390002 A. camansi Kapiak April-21-04 Dec.-08-06 32 Seed, Papua New Guinea 000394002 A. camansi Kapiak April-21-04 Dec.-08-06 32 Seed, Papua New Guinea 000395002 A. camansi Kapiak April-21-04 Mar.-19-07 35 Seed, Papua New Guinea 000398005 A. camansi Kapiak April-21-04 Apr.-09-07 36 Seed, Papua New Guinea 000499003 A. camansi Kapiak April-21-04 Feb.-19-07 34 Seed, Papua New Guinea 000500002 A. camansi Kapiak April-21-04 Mar.-12-07 35 Seed, Papua New Guinea 000501004 A. camansi Kapiak April-21-04 May-05-07 37 Seed, Papua New Guinea 31 NTBG ID Species Cultivar Planted date First fruit appear Month before first fruit Source 000501005 A. camansi Kapiak April-21-04 Feb.-12-07 34 Seed, Papua New Guinea 000502002 A. camansi Kapiak April-21-04 Nov.-25-08 55 Seed, Papua New Guinea 000503004 A. camansi Kapiak April-21-04 Jan.-07-09 57 Seed, Papua New Guinea 030034001 A. altilis x A. mariannensis Meinpadahk April-28-04 Jun.-25-07 38 Roots, Kahanu Garden 030034002 A. altilis x A. mariannensis Meinpadahk April-28-04 Jun.-18-07 38 Roots, Kahanu Garden 030041001 A. altilis x A. mariannensis Rotuma April-28-04 May-13-07 37 Roots, Kahanu Garden 030045001 A. altilis x A. mariannensis Yap April-28-04 Apr.-16-07 36 Roots, Kahanu Garden 040051001 A. altilis Afara January-03-06 May-21-08 29 Roots, Kahanu Garden 030033001 A. altilis Meitehid June-20-05 Sep.-18-07 27 Roots, Kahanu Garden 32 NTBG ID Species Cultivar Planted date First fruit appear Month before first fruit Source 030035001 A. altilis Otea January-03-06 May-21-08 29 Roots, Kahanu Garden 030037001 A. altilis Porohiti April-28-04 Jun.-18-07 38 Roots, Kahanu Garden 040518001 A. altilis Rare autia January-03-06 Nov.-02-07 23 Roots, Kahanu Garden 030042001 A. altilis Toneno April-28-04 Apr.-16-07 36 Roots, Kahanu Garden 040063001 A. altilis Ulu fiti June-20-05 Oct.-04-07 28 Roots, Kahanu Garden 030028001 A. altilis White June-20-05 Jul.-24-07 25 Roots, Kahanu Garden 070659021 A. altilis Ma’afala November-21-08 Sep.-02-10 22 in vitro, Murch 070659022 A. altilis Ma’afala October-20-08 Sep.-03-10 23 in vitro, Murch Average 34 33 2.3.2. Breadfruit seasonality Individual breadfruit cultivars (Artocarpus spp.) produced fruit at different times throughout the year with the major fruiting season from July to November (Figure 2-1 a&b). Monthly fruit production during the peak season was as high as 145 fruit per tree for Meinpadahk, and as low as 16 fruit for Meitehid. Some cultivars, such as Rotuma (hybrid), White (A. altilis), Toneno (A. altilis), and Mos en Samoa (A. altilis) had another small production peak during the spring (146 fruit for the entire year). Highly productive cultivars including Meinpadahk (hybrid), Rotuma (hybrid), and Mos en Samoa (A. altilis) maintained twice the average fruit production throughout the year (Figure 2-1a). Seasonal differences were less obvious for breadnut (A. camansi) and fruit production was lower (Figure 2-1b). About 70% of the trees in our study were in fruit for > 80% of the years measured (Figure 2-2). Figure 2-1 a 050100150200250Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecAverage fruit number per treeMonthAfara Meinpadahk Meitehid Mos en SamoaOtea Porohiti Puou Rare autlaRotuma Toneno Ulu fiti WhiteYap A. camansi A. mariannensis Average 34 Figure 2-1 b Figure 2-1 Average fruit number per tree of breadfruit cultivars planted from 2008 to 2012 (a). Each cultivar has one tree except for A. camansi (n=10) and Meinpadahk (n=2). Average fruit number per month of Artocarpus altilis (n=10), A. camansi (n=4), A. mariannensis (n=1), and A. altilis × A. mariannensis (n=10) from 2008 to 2012 (b). Bars represent the standard error of the mean of each month over the 4-year data collection period Figure 2-2 a0102030405060708090100Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecAverage fruit numberMonthArtocarpus altilis A. altilis × A. mariannensisA. camansi A. mariannensis0%20%40%60%80%100%Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecYears in male flowers/edible fruit/fruitMonthMale Flowers Edible Fruit Fruit 35 Figure 2-2 b Figure 2-2 The average percentage of years (a) and average percentage of breadfruit trees (b) that breadfruit trees bore fruit, edible fruit and male flowers from 2007 to 2012 in National Tropical Botanical Garden in Kauai, Hawaii. Edible/harvestable fruit refers to full-sized fruit, mature fruit, and ripe fruit. Bars represent the standard error of the mean Seasonality in Kauai and Maui In terms of seasonality difference between Kauai and Maui, most cultivars, including Afara, Otea, Meinpadahk, Porohiti, Meitehid, Ulu fiti, and Yap, bore edible fruit (full size, mature and/or ripe fruit) at similar times (Figure 2-3). Meitehid had a longer low season in Kauai that lasted from April to August. Ulu fiti maintained the same seasonality as well as the same likelihood of fruiting in Kauai and Maui. Yap tended to be less seasonal than most cultivars and it kept this attribute when it was planted in Kauai. Puou, and White shared similar seasonality in Kauai and Maui, with a 2-month delay in the onset of the low season in Kauai. Rotuma and Toneno displayed different seasonality profiles in Kauai than in Maui. In Maui, Rotuma has a 0%20%40%60%80%100%Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecTrees in male flowers/edible fruit/fruitMonthMale Flowers Edible Fruit Fruit 36 distinct season between November and February and a low season between April and August. However, when it was planted in Kauai, Rotuma produced fruit much more sporadically and was less seasonal. In Maui, Toneno has a peak season from October to January and a low season from March to July. In Kauai, the peak season shifted to May to July and the low season moved to July to September. Overall, edible fruit season remained relatively consistent between Maui and Kauai. 0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthAfara in Kauai Afara in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthOtea in Kauai Otea in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthMeinpadahk in KauaiMeinpadahk in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthA. mariannensis in KauaiA. mariannensis in Maui 37 0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthPorohiti in KauaiPorohiti in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthMeitehid in KauaiMeitehid in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthYap in Kauai Yap in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edbile fruitMonthUlu fiti in Kauai Ulu fiti in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthRotuma in Kauai Rotuma in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthPuou in Kauai Puou in Maui 38 Figure 2-3 Comparison of individual edible fruit seasonality profiles of breadfruit cultivars planted in the National Tropical Botanical Garden in Kauai and Maui, Hawaii. Edible/harvestable fruit refers to full-sized fruit, mature fruit, and ripe fruit Similar trends were seen for the male flower season between trees in Kauai and Maui (Figure 2-4). Afara and Yap had almost the same seasonality and number of years with trees producing male flowers. Cultivars such as White, Porohiti and Meitehid shared similar seasonality in Kauai and Maui, but had a greater number of years with male flowers. Rotuma, Ulu fiti, and Otea had similar seasonality but a 2 to 3 months longer peak season. Puou, Meinpadahk, and Toneno experienced a 2-month delay in the flowering season in Kauai. Overall, breadfruit kept the same male flower seasonality between Kauai and Maui. 0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthWhite in Kauai White in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in edible fruitMonthToneno in Kauai Toneno in Maui 39 0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthA. mariannensis in KauaiA. mariannensis in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthWhite in Kauai White in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthMeitehid in KauaiMeitehid in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthPorohiti in KauaiPorohiti in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthAfara in Kauai Afara in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonth Yap in Kauai Yap in Maui 40 Figure 2-4 Comparison of individual male flower seasonality profiles of breadfruit cultivars planted in the National Tropical Botanical Garden in Kauai and Maui, Hawaii 0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthRotuma in Kauai Rotuma in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthUlu fiti in Kauai Ulu fiti in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthOtea in Kauai Otea in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthPuou in Kauai Puou in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthMeinpadahk in Kauai Meinpadahk in Maui0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecYears in male flowersMonthToneno in Kauai Toneno in Maui 41 2.3.3. Breadfruit productivity/fruit number On average 64% of the fruit was produced during the peak season for A. altilis and 58% for hybrids (Figure 2-5). The average fruit number (A. altilis and hybrid) during the entire year was approximately 40 fruit per month; 59 fruit per month during the peak season; and 26 fruit per month during the low season. Dugdug (A. mariannensis) had the most distinct peak season from August to November with a fruit production of 160 (70%). A. camansi trees produced an average of 47 ± 8 fruit produced by the juvenile trees. As the trees aged, the number of fruits increased to 130 ± 22 fruit per tree after 7 years and continued to increase throughout the study (Figure 2-5). After 7 years, hybrids (A. altilis × A. mariannensis) produced an average of 131 ± 36 fruit per tree, while A. altilis produced an average of 129 ± 28 fruit per tree (Table 2-3). For 7-year-old breadnut (A. camansi) trees, the total fruit production was lower at about 52 ± 9 fruit per tree. Hybrids produced higher yields than the other species at both 4 and 7 years after planting. Based on these 7 years of field data, most cultivars showed a linear increase in total fruit number per year after initiating fruit production. As a group, the total fruit number increased from 3 to 7 years after planting following a linear equation,𝑦 = 27.18𝑥 − 21.43, R2=0.9684 (Figure 2-5). The average increase in fruit number per year was about 25.0, but it varied among cultivars. Porohiti had the highest growth rate at 42.9 (𝑦 = 42.9𝑥 − 37.8, R2=0.9258), followed by Meinpadahk at 42.3 (𝑦 = 42.3 − 40.1, R2=0.9537), and White at 38.7 (𝑦 =38.7𝑥 − 30.1, R2=0.8131). 42 Figure 2-5 Average fruit number per year of breadfruit cultivars planted in the National Tropical Botanical Garden in Kauai, Hawaii from 2 years to 8 years old. Bars represent the standard error of the mean over the individual tree. A. camansi (n=10).y = 27.181x - 21.428R² = 0.9684050100150200250300350 2 Years 3 Years 4 Years 5 Years 6 Years 7 Years 8 YearsTotal fruit number per yearYears after being plantedA. camansi Afara A. mariannensisMeinpadahk Meitehid Mos en SamoaOtea Porohiti Rare autlaRotuma Toneno Ulu fitiWhite Yap AverageLinear (Average) 43 Table 2-3 The summary of the total fruit number, average fruit weight, and yield in Artocarpus species after being planted 4 years and 7 years. Different plant number exists due to the difference in plant age Years after being planted Category Artocarpus camansi Artocarpus mariannensis Artocarpus altilis A. altilis x A. mariannensis 4 Years Plant number 10 1 7 4 Total fruit number 11±4 6.00 45±10 49±20 Average fruit weight (g) 344.00 - 1181.12 735.47 Yield (t/hectare) 0.38 - 3.20 3.80 7 Years Plant number 10 1 5 4 Total fruit number 52±9 106.00 129±28 131±36 Average fruit weight (g) 1612.26±71.70 563.5±52.95 1170.01 2038.02 Yield (t/hectare) 6.7 5.7 10.46 17.12 9 Years Plant number 10 1 4 4 Canopy area (m2) 41.73 32.41 23.26 37.90 % Leaf area 84.30 96.43 90.33 95.16 Perimeter (m) 0.91 0.89 0.94 1.07 Height (m) 7.61 5.51 5.14 5.91 44 2.3.4. Breadfruit fruit weight The harvested fruit generally weighed between 1.0 kg to 2.0 kg during the study years depending on the cultivar (Figure 2-6). The average fruit weight was 1.2 kg across cultivars. However, differences in fruit size were found among cultivars and the extent of these differences increased as the trees grew older. For 4-year-old trees, Toneno, Rotuma, Rare autia, and Otea cultivars had average fruit weights over 1.0 kg; Afara and Mos en Samoa weighed over 0.5 kg; and Meitehid weighed less than 0.5 kg. At 7 years after planting, Yap, Toneno, Rotuma, and Mos en Samoa grew heavier, with fruit over 1.5 kg; Meitehid, Meinpadahk, and Rare autia weighed over 1.0 kg, while Porohiti weighed over 0.5 kg. Over this 3-year-period, Rotuma and Porohiti produced increasingly heavier fruit with an average increase around 0.58 kg. Most cultivars, including Meitehid, Meinpadahk, Rare autia, Mos en Samoa, Ulu fiti and White, produced fruits that increased in weight by 0.98 kg over the 3 years of production. Seven years after planting, the average fruit weight for hybrids (A. altilis × A. mariannensis) was 2.0 ± 0.63 kg, while the average weight for A. altilis was 1.2 ± 0.15 kg (Table 2-3). 45 Figure 2-6 Average fruit weight for breadfruit cultivars from 2 years old to 8 years old. Bars represent the standard error of the mean for fruit produced in each year. Please note: Data was unavailable for certain years in study and a different number of fruits was measured for each tree of each variety in each year 2.3.5. Breadfruit yield Based on the planting density of 100 trees/ha used in our study, the average projected yield for 4-year-old trees was (3.92 ± 0.27) t/ha, with the highest yield of (5.5 ± 0.02) t/ha for Otea and the lowest yield of (1.52 ± 0.02) t/ha (Figure 2-7). At 7 years after planting, the projected average yield reached (12.68 ± 1.01) t/ha but was as high as (18.74 ± 0.05) t/ha for Meinpadahk and as low as (4.56 ± 0.04) t/ha for Rare autia. The average annual yield for the hybrid cultivars (A. altilis × A. mariannensis) included in our study was 17.12 t/ha after 7 years, while for A. altilis, the number was lower at 10.46 t/ha. 05001000150020002500300035002 Years 3 Years 4 Years 5 Years 6 Years 7 Years 8 YearsAverage fruit weight (g)Years after Being PlantedA. camansi Afara A. mariannensis MeitehidMeinpadahk Mos en Samoa Otea PorohitiRare autia Rotuma Toneno Ulu fitiWhite Yap 46 Figure 2-7 Yield for breadfruit cultivars from 2 years to 8 years old. Data is unavailable for certain years in study. Bars represent the standard error of the mean over the individual tree. A. camansi (n=10), Meinpadahk (n=2). The yield was calculated as follow: Average fruit weight × (Average total fruit number per year −Aborted fruit − Fruit with rots) × 100 trees 2.3.6. Tree size and growth According to our results, hybrids had the largest trunk circumference (1.07 m) while A. mariannensis had the smallest (0.89 m) (Table 2-3). Hybrids had a larger canopy area (37.90 m2), higher percent leaf area (95.16%) and were taller (5.91m) than A. altilis (23.26 m2, 90.33%, and 5.14 m, respectively). Breadnut (A. camansi) had the highest tree height at 7.61 m and the largest canopy area 41.73 m2; the percent leaf area was the lowest. y = 2.4461x - 2.591R² = 0.96420510152025302 Years 3 Years 4 Years 5 Years 6 Years 7 Years 8 YearsAnnual yield (t/hectar)Years after being plantedA. camansi Afara A. mariannensisMei tehid Meinpadahk Mos en SamoaOtea Porohiti Rare autiaRotuma Toneno Ulu fitiWhite Yap AverageLinear (Average) 47 2.3.7. Commercial breadfruit Ma’afala The fruiting season for commercial breadfruit cultivar, Ma’afala, was from Oct. to Dec. after being planted 3 years and July to Oct. after being planted 4 years (Figure 2-8a). The average fruit weight of Ma’afala grown in Kauai was 576 g, with the smallest fruit measured at 425 g in May 2011 and the largest fruit measured at 886 g in September 2011 (Figure 2-8b). Figure 2-8 a Figure 2-8 b Figure 2-8 Total fruit number (a), and average fruit weight (b) for breadfruit cultivar Ma’afala in the National Tropical Botanical Garden at on Kauai. The number is an average of two trees planted in the garden in 2011 and 2012. 0100200300400500Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMa'alafa total fruit number2011 2012020040060080010001200Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMa'afala average fruit weight (g)2011 2012 48 2.4. Discussion 2.4.1. Breadfruit seasonality and production in Kauai The major season for breadfruit production in our study of Kauai is from July to November. However, not all cultivars produced edible fruit at the same time and there were definite seasonal patterns. In our study, breadfruit trees produced some edible fruit each month every year, therefore careful selection of cultivars can ensure yearlong production of breadfruit. The fruit matured 3 to 4 months later than the male flowers emerged, which is consistent with previous studies (Jones et al., 2010). Breadfruit produced around 260 to 280 fruit per tree during the peak season, which is higher than previous estimates of about 150–250 fruit per tree per year (Morton 1987; Ragone 2011). Based on an average fruit moisture content of about 68% (Jones et al., 2011b), hybrids yield 5.4 t/ha dry fruit and A. altilis yields 3.4 t/ha dry fruit by 7 years after planting. This is lower than the estimated breadfruit production of 6 t/ha on a dry weight basis in an orchard production system in Bowers’s study in 1981. The fruit number and fruit yield presented in this study showed a linear increase from 3 to 7 years after plant. The linear relationship and high R2 value suggest that the production will continue to increase in the future and the full potential fruit production of a mature orchard is not reached. Nevertheless, our reported yield still compares favorably to the average global yields of rice wheat, or corn at (4.43, 3.25, and 5.64) t/ha, respectively (USDA, 2015b). The protein production for breadfruit (including both A. altilis and hybrids) is 0.16 t/ha on average, based on 1.2% protein content reported by Jones et al. (2010). 49 Hybrids showed an advantage in fruit number, weight, and yield. The examination of growth tree size and growth also showed that hybrids had larger canopy area, higher percent leaf area and taller tree. Based on these data, it could be concluded that heterosis may exist in Artocarpus hybrids. Heterosis shows the superiority of growth rate, reproductive success, and yield (Lippman and Zamir, 2007). Hybridization and introgression have been observed and applied to increase crop yields since ancient times (de Ribou et al., 2013). An increase in yield ranging from 15% to 50% has been reported for maize, sorghum, rice, and sunflower. Hybrids also can have advantages for pathogen-resistance traits or better adaptation to extreme climate or new light regimes (de Ribou et al., 2013). In spite of high fruit production, fruit dropping was observed in the study. Given this observation, it may be beneficial to thin the fruit and/or prune the tree to encourage fruit maturation, as is commonly practiced with other tree fruits such as apple, pear, peach, and cherry (Robinson 2007; Sane et al., 2012). 2.4.2. Comparison of breadfruit productivity across locations The yield data obtained in Kauai was higher than what has been reported using the same genetic stock (Colones of Ma’afla and Rotuma) in New Caledonia (Lebegin et al., 2007) (Table 2-4). In New Caledonia, Rotuma had an average fruit weight of 679 ± 123.7 g, which is less than half of that observed in Kauai 1443 ± 65.4 g. Likewise, fruit length was 11.7 ± 0.3 cm in New Caledonia compared to 16.4 ± 0.3 cm in Kauai. The average weight and size in Kauai were closer to what were observed in Maui with a range of 12–16 cm × 12–15 cm and an average weight at 1.1 kg (Ragone, 50 2011). Ma’afala fruits were also about twice as large in the Kauai collection with an average fruit weight of 609 ± 21 g compared to 300 ± 72.1 g in New Caledonia (Table 2-4). Ma’afala fruit size was also significantly larger for trees grown in Kauai with fruit measuring 12 ± 0.2 cm compared to 9.0 ± 0.9 cm in New Caledonia (Lebegin et al., 2007). The average weight and size of Ma’afala fruits in Kauai were closer to previous reports in the existing literature (12–16 cm × 10–13 cm, 0.8 kg) (Ragone, 2011). While New Caledonia and Kauai are similar distances from the equator (Table 2-5), the trees planted in New Caledonia suffered from water logging issues and a suspected problem with soil-borne diseases (Lebegin et al., 2007). As such, the lower fruit sizes and productivity observed in New Caledonia are likely a result of micro-climatic and biotic variables rather than the overall environment. Table 2-4 Comparison of fruit growth between Rotuma and Ma’afala in Kauai and New Caledonia (Lebegin et al., 2007) Rotuma Ma'afala Location New Caledonia Kauai New Caledonia Kauai Average fruit weight (g) 679±123.7 1143±65.4 300±72.1 609±21 Average fruit size (cm) 11.7±0.3 16.4±0.3 9.0±0.9 12±0.2 51 Table 2-5 Comparison of the environmental and climate factors for breadfruit plantings in Kauai and Maui, Hawaii, and New Caledonia (WRCC, 2016) Kauai Maui New Caledonia Location 21°88’79.43”N, 159°49’23.15”W 20°47′57.07″N, 156°02′18.42″W 19-22°S, 158-162°E Mean temp. (°C) 24.4 24.3 23.1 Mean max temp. (°C) 29 27.1 26 Mean min temp. (°C) 24.4 19.7 20.2 Precipitation (mm) 939 2051 1530 Compared to previous studies with breadnut (A. camansi) trees, the data obtained in Kauai showed higher variation (Table 2-6). In Roberts-Nkrumah’s experiment (Roberts-Nkrumah, 2005), three breadnut trees were grown at the University of the West Indies Field Station (UWI-FS) in Valsayn, Trinidad and Tobago (lat. 10°2’ to 11°12’ N, long. 60°30’ to 61°56’ W), which has a mean temperature of 26.8 °C and mean precipitation of 1575 mm. In her study, there were positive correlations between seed mass and seed number (r = 0.87), seed mass and fruit mass (r = 0.83), and seed number and fruit mass (r = 0.77). There was no difference between years or plant age. The fruit size and weight observed in Kauai were larger than they were in UWI-FS in all ages. However, seed number and seed mass were lower in Kauai after 6 and 8 years than they were in UWI-FS. These comparisons indicate that the positive correlations found in Roberts-Nkrumah’s study may not apply when comparing data between her study and our study (Table 2-7). In Kauai, breadnut had a higher seed weight than at UWI-FS. Breadnut in Kauai had a lower percentage 52 of seed mass per fruit at all ages. Seed masses from both locations were lower than 50% of the fruit. Fruit and seed production per tree varied dramatically from year to year (30 kg to 140 kg, 10 kg to 60 kg, respectively). Trees in Kauai were grown from seeds collected from the wild and cultivated trees in Papua New Guinea, the center of origin for this species, while the ones at UWI-FS were likely from a single seed source. Variation in fruit and seed production between individuals was found in Kauai. 53 Table 2-6 Comparison of Artocarpus camansi (breadnut) production in McBryde Garden in Kauai with the University of the West Indies Field Station in Valsayn, Trinidad, and Tobago (Roberts-Nkrumah 2005) Years After being planted Location Average number of fruit Average fruit weight (kg) Average fruit length (cm) Average fruit width (cm) Number of seeds per fruit Seed weight (g) Seed mass per fruit (g) Seed production per tree (kg) Fruit production per tree (kg) Seed mass/ fruit mass (%) 5 years UWI Field Station 126 1.14 16.16 13.18 60 8.14 471.28 59.38 143.64 41.00 McBryde Garden 19 1.51 16.50 15.00 44 11.41 502.00 9.54 28.61 33.33 6 years UWI Field Station 68 1.06 16.54 13.11 61 8.34 502.79 34.36 72.43 46.00 McBryde Garden 36 1.92 17.77 16.77 53 8.42 443.33 15.92 69.10 23.03 7 years UWI Field Station 25 0.89 14.41 12.40 44 7.56 327.78 8.30 22.54 36.00 McBryde Garden 52 1.61 18.27 15.37 49 8.73 428.26 22.23 83.68 26.56 8 Years UWI Field Station 30 0.92 14.52 12.21 59 8.17 475.00 14.09 27.30 42.00 McBryde Garden 23 1.33 18.66 14.55 31 9.18 284.46 6.63 31.06 21.34 54 2.4.3. Comparison of breadfruit seasonality across locations As previously reported there does not appear to be an influence of precipitation patterns on seasonality in breadfruit (Quartermain, 2007). The McBryde Garden on Kauai shares a similar rainy season as the Kahanu Garden on Maui. However, the Kauai location receives about half of the annual precipitation reported for the Kahanu Garden (Table 2-5) (Shi et al., 2007). The seasonality of male flowers did not vary between the two locations, indicating that the amount of precipitation is not the dominant factor in determining edible fruit/male flower seasonality. Jones et al. proposed a hypothesis that seasonality of breadfruit is closely related to the distance from the equator, potentially due to differences in the light quality/spectrum throughout the season (Jones et al., 2010). In this hypothesis, breadfruit flowering is induced when the sun reaches its zenith before the summer months and subsequent fruiting extends throughout the summer months. Kauai and Maui share a similar longitude and latitude (Table 2-5); the similarity of the breadfruit seasonality in these datasets provides evidence in support of this hypothesis, but further studies in more widely different locations are required. 2.4.4. Commercial breadfruit Ma’afala Ma’afala has been the most widely distributed breadfruit cultivar. In the Kahanu Garden germplasm collection on Maui, mature Ma’afala trees produced fruits most reliably from July to December (Jones et al., 2010). Juvenile clones of this tree planted on Kauai displayed a slight delay in the first two fruiting seasons. However, as the trees matured, the season became more similar to that of more established trees in 55 the Kahanu Garden on Maui, with the most fruits being produced in July of 2012. Based on these data, a slight shift in seasonality of juvenile breadfruit should be considered for agricultural applications. The flowering periods occurred 3 to 4 months earlier than the fruiting season, which is consistent with previous observations (Jones et al., 2010). The recommended planting density for Ma’afala agricultural practice is 120 trees/ha, which means Ma’afala could be expected to yield approximately 20 t/ha by 8 years after planting. Based on a protein content of 2.6% (Jones et al., 2011a), 20 t/ha production of Ma’afala translated to a protein yield of 0.52 t/ha, which is higher than rice, wheat, and potato, but lower than corn and soybean (Table 2-7). Another factor that needs to be taken into account is that other staples, soybean or corn have a long history of cultivation and commercialization, while breadfruit agriculture has very limited studies. The potential yields of a mature breadfruit orchard can be greater than what is reported here. Table 2-7 Comparison of the protein yields between Ma’afala and other staples Staple Protein Content (%) Yield t/ha Protein yield t/ha Cassava 1.11 13.52 0.15 Potato 1.31 19.42 0.25 Rice 6.71 4.463 0.29 Wheat 12.21 3.253 0.40 Ma’afala 2.6 20 0.52 Corn 9.51 5.643 0.54 Soybean 381 2.73 1.03 1 (FAO, 1981), 2 (USDA, 2015c), 3 (FAOSTAT, 2013) 56 2.5. Summary The current data describes breadfruit growth habits with a comparison of yield and seasonality, demonstrating the range of diversity among cultivars. Generally speaking, breadfruit, including hybrids, requires around 30 months to fruit from root cuttings. Once established, a breadfruit tree can produce over 250 fruit a year with an average weight of 1.2 kg. Around 60% of fruits are produced during the season from July to November. Our study demonstrated that the expected yield for breadfruit after 7 years is 10-15 t/ha. Differences exist in cultivars. As expected, hybrids have many advantages, including yield, average larger fruits for mature trees, and denser tree canopies. Even though some cultivars (A. altilis: Toneno and White; A. altilis × A. mariannensis: Rotuma and Meinpadahk) have certain agricultural advantages, selecting cultivars for international distribution also depends upon the flavor, texture, taste, etc. of the cultivar. To date, Ma’afala is the first breadfruit cultivar available for widespread distribution. In vitro propagated Ma’afala trees produced fruits within 23 months and these data indicate that an orchard of established Ma’afala trees will produce 20 t/ha of fruit by 8 years. This will translate to 0.52 t/ha protein yield which is higher than wheat, rice, and potato, and close to corn and soybean. Seasonality for male flower and fruit remains similar between the two locations compared in this project, supporting the hypothesis that seasonality of breadfruit is closely related to the distance from the equator and incidence of light (Jones et al., 2010). Further studies should determine if fundamental characteristics of breadfruit cultivars are conserved across disparate geographic regions and distant climates. 57 Chapter 3. Amino Acid Analysis of Breadfruit Protein 3.1. Synopsis The fundamental requirement for maintaining good health is access to sufficient food of adequate quality (WHO, 2007), but adequate food is limited in many parts of the world and climate change seems likely to disrupt food supplies by 2050 (Porter and Xie, 2014). In comparison to other tropical crops, breadfruit contains an average of 3.9 % protein on a dry weight basis, which is 1.15 % higher than cassava, 1.1 % higher than banana, and 0.3 % higher than sweet potato (Jones et al., 2011a). One breadfruit cultivar, Ma’afala, has an average of 7.6 % protein based on dry weight, which is comparable to rice (Jones et al., 2011a). Previous work has shown that breadfruit contains all of the essential amino acids (Golden and Williams, 2001; Morton, 1987). Leucine (0.61 ± 0.01 g/100 g) and lysine (0.8 ± 0.22 g/100 g) made up to 30 % of the total amino acid content during the ripe developmental stage of breadfruit (Golden and Williams, 2001). However, this research was based on only one (Golden and Williams, 2001) or few (Morton, 1987) cultivars and protein quality was not assessed. Protein quality is determined by the essential amino acid content and ratio of amino acids (WHO, 2007). Essential amino acids are indispensable and cannot be synthesised by the human body including lysine (lys), leucine (leu), threonine (thr), tryptophan (trp), histidine (his), isoleucine (ile), valine (val), phenylalanine (phe), tyrosine (tyr), methionine (met), and cysteine (cys) (WHO 2007 ). Since protein content varied widely depending on the cultivar (Jones et al., 2011a), an assessment of the variability of proteins between cultivars and of the protein quality of individual cultivars was warranted. 58 3.1.1. Objectives The objective was to evaluate and describe the variation in the amino acid composition of a genetically diverse group of breadfruit cultivars growing in a single location to determine how the essential amino acids vary among cultivars. 3.2. Materials and method 3.2.1. Breadfruit sample collection and preparation A detailed description of the sample collection and experimental design has been published previously (Jones et al., 2011a, 2013b). Three mature breadfruits were collected from 49 breadfruit cultivars including 41 Artocarpus altilis and 8 hybrids (A. altilis × A. mariannensis) (Table 3-1). Since different breadfruit cultivars produce fruit in different months, the collection process lasted several months during November 2008 to December 2010 (Jones et al., 2010, 2013b). After removing the stem, fruits were inverted for about 1 h to drain latex. The skin was removed with a good quality household vegetable peeler, the fruit was cut into quarters, and the core was removed. The edible portion of the fruit was cut into 2 cm slices, frozen, and shipped to the University of British Columbia Okanagan. All the breadfruit samples were stored at −86 °C before analysis. 59 Table 3-1 The cultivar list of breadfruit (Artocarpus altilis and A. altilis × A. mariannesis) used in the amino acid analysis Grid NTBG ID Cultivar Plant date Species Island of origin 8 900233002 Pulupulu 28/03/1986 A. altilis Samoa 9 790492001 Porohiti 17/09/1975 A. altilis Society Islands 12 790488001 Toneno 11/09/1975 A. altilis Society Islands 13 790491001 Tuutou 11/09/1975 A. altilis Society Islands 16 790485001 Puou 16/09/1975 A. altilis Society Islands 20 790486001 Roihaa 20/09/1975 A. altilis Society Islands 27 790487001 Huehue 17/09/1975 A. altilis Society Islands 30 780333001 Ahani 15/09/1975 A. altilis Society Islands 32 780325001 Afara 13/09/1975 A. altilis Society Islands 35 890258001 Ulu fiti 08/02/1985 A. altilis Samoa 36 800269001 Mahani 15/09/1975 A. altilis Society Islands 38 810289002 Yellow 06/01/1978 A. altilis Seychelles 39 780327001 Otea 11/09/1975 A. altilis Society Islands 40 780330002 Fafai 17/09/1975 A. altilis Society Islands 43 810290001 White 05/01/1978 A. altilis Seychelles 47 780291001 Havana pataitai 17/09/1975 A. altilis Society Islands 49 790497002 Meinuwe 05/01/1978 A. altilis Micronesia 51 780338001 Tapehaa 03/01/1975 A. altilis Society Islands 55 770517001 Ma’afala 01/01/1975 A. altilis Samoa A7 900232001 Atu 02/04/1986 A. altilis Cook Islands A8 900264001 Uto ni viti 30/03/1986 A. altilis Fiji B6 900237001 Mei puou 01/04/1986 A. altilis Marquesas Islands B8 900242001 Mei kopumoko 26/03/1986 A. altilis Marquesas Islands D9 910271001 Mei uhpw 12/07/1987 A. altilis Micronesia 60 Grid NTBG ID Cultivar Plant date Species Island of origin E5 900266002 Meiarephe 29/03/1986 A. altilis Micronesia F6 900241001 Mei aueka 29/03/1986 A. altilis Marquesas Islands H7 900246001 Tuutou auena 01/04/1986 A. altilis Society Islands I6 900247001 Tuutou ooa 29/03/1986 A. altilis Society Islands I8 900249002 Anahonaho 01/04/1986 A. altilis Society Islands K7 900260001 Samoan 26/03/1986 A. altilis Samoa M6 900262001 Manua 01/04/1986 A. altilis Samoa P7 890464001 Ouo 30/07/1985 A. altilis Society Islands P8 880690001 Kea 01/04/1986 A. altilis Tonga R4 890477001 Uto samoa 01/08/1985 A. altilis Samoa S7 890152002 Puurea 01/08/1985 A. altilis Society Islands T6 890460001 Puaa 29/07/1985 A. altilis Society Islands V3 890463001 Patara 29/07/1985 A. altilis Society Islands V4 890159002 Meriaur 26/07/1985 A. altilis Palau V6 890470001 Furau 26/07/1985 A. altilis Samoa W3 890471001 Uto dina 29/07/1985 A. altilis Samoa Y1 890154001 Hamoa (Maopo) 11/02/1985 A. altilis Society Islands 1 790489001 Piipiia 13/09/1975 A. altilis x. A. mariannensis Society Islands 19 890161001 Yuley 10/02/1985 A. altilis x. A. mariannensis Micronesia A9 910269001 Faine 15/07/1987 A. altilis x. A. mariannensis Micronesia B5 900255001 Meinpwahr 29/03/1986 A. altilis x. A. mariannensis Micronesia E6 910272002 Meinpohnsakar 09/07/1987 A. altilis x. A. mariannensis Micronesia J9 910268001 Meion 09/07/1987 A. altilis x. A. mariannensis Micronesia L8 890183002 Midolab 08/02/1985 A. altilis x. A. mariannensis Palau Z9 790494001 Meinpadahk 05/01/1978 A. altilis x. A. mariannensis Micronesia 61 3.2.2. Reagents AccQFluor kits, comprising borate buffer (AccQFluor 1), reagent powder (AccQFluor 2A) and reagent diluent (AccQFluor 2B), and AccQ Tag (6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, AQC) were purchased from Waters (Milford, USA). Both reagents were prepared and stored according to the Instruction Manual from Waters (Waters AccQ Tag Chemistry Package Instruction Manual, Revision 1). Acetonitrile (HPLC grade) and HCl (1 N) were purchased from Fisher Chemical (Fair Lawn, New Jersey). KOH and HCl (37 %) were obtained from Sigma–Aldrich (Louis, USA). Norleucine (Sigma Chemical Company, Louis, USA) stock solution (2.5 mM) was made in 0.1 N HCl. The mixed amino acid standard solution (each at 2.5 ± 0.1 μmol/mL, except cystine at 1.25 ± 0.1 μmol/mL) was Pierce™ Amino Acid Standard H (comprising 18 amino acids) from Thermo Scientific (Rockford, USA). Water used in this study was purified with DirectQ 3 Water purification System (EMD Millipore Corporation, Billerica, USA). 3.2.3. Preparation of amino acid samples 200 mg of each frozen sample (49 cultivars × 3 fruits × 3 replications) was weighed and transferred to a 1.5 mL MCT graduated natural tube (Fisherbrand, Mississauga, ON). The sample was placed in a CentriVap DNA Vacuum Concentrator (Labconco, Kansas City, USA) for an 18 h drying process, including 999 min centrifugation at 1725 RPM. The dried sample was weighed to determine the dry matter, sliced, and transferred to a screw cap Pyrex vial (17 × 60 mm) (Fisherbrand). An aliquot of 20 μL of the 2.5 mM norleucine internal standard and 2000 μL 6.0 N HCl 62 were added, the vial was flushed with nitrogen, and then quickly capped. The hydrolysis was performed at 110°C for 19 h in a standard heating block (VWR, Radnor, USA). 500 μL hydrolyzed sample was filtered through an Ultrafree MC Centrifugation Unit (Fisherbrand). An aliquot of 1 μL of the hydrolyzed protein sample was diluted to a total volume of 40 μL with borate buffer (AccQFluor Reagent 1). 3.2.4. Derivatization of amino acids The derivatization was achieved by reacting 20 μL diluted sample or protein hydrolysis standard solution with 20 μL AccQTag derivatizing reagent AQC (6-aminoquinolyl-N-hydroxysuccinimidyl carbamate) in 60 μL borate buffer (AccQFluor 1). All the reagents were pipetted into a 250 μL glass conical insert bottom spring (6 × 29 mm) (Canadian Life Science, Peterborough, Canada), agitated moderately, and kept inside a screw cap injection vial. The vial was heated in the heat block at 55°C for 10 min to complete the reaction. After regaining room temperature, 10 μL derivatized sample was injected into the high performance liquid chromatography (HPLC) instrument. 3.2.5. HPLC analysis The analysis of breadfruit amino acid was performed on a Waters 2659 HPLC Separations Module comprising of a multi λ fluorescent detector (Waters 2475) and a photodiode array detector (Waters 2998), controlled by Empower 3 software (Waters, Milford, USA) and data system. The amino acids were separated on a 4 μm NavaPak C column (3.9 × 300 mm) (Waters, Milford, USA). Chromatographic analysis was 63 performed at room temperature (32 ± 5°C) using gradient elution shown in Table 3-2: eluent A was ACCQ Tag/water (10/90, % v/v) and eluent B was acetonitrile/water (50/50, % v/v). The peaks were detected by fluorescence over a period of 75 min with an excitation wavelength of 250 nm and an emission wavelength of 395 nm. Table 3-2 HPLC gradient elution for the breadfruit amino acid study Time (min) Flow %A % B Curve 1 100 0 2 1 93 7 6 4 1 90 10 6 28 1 80 20 3 32 1 75 25 8 38 1 61 33 4 50 1 35 65 6 52 1 0 100 6 55 1 100 0 6 60 1 100 0 2 Eluent A: ACCQ·Tag/water (10/90, v/v) and Eluent B: acetonitrile/water (50/50, v/v) 3.2.6. Data analysis Genesis 1.7.5 (Institute for Genomics and Bioinformatics; Graz, Austria) was used to build the essential amino acid profile. All statistical analyses were conducted using RStudio Version 0.98.1062 (RStudio Inc. USA) with a type 1 error rate of 0.05. Essential amino acid data for other staples listed in this article are reported by the Food and Agriculture Organization of the United Nations (FAO, 1981). 64 3.3. Results 3.3.1. Quantification of essential amino acids All essential amino acids were found in breadfruit (Artocarpus altilis) and hybrids (A. altilis × A. mariannensis). Significant differences were observed in the essential amino acid content of the protein among breadfruit cultivars and hybrids (Figure 3-1). Phe, leu, ile, and val were found to be the most abundant essential amino acid in breadfruit. When comparing individual essential amino acids, Ma’afala (Samoa), Afara, and Hamoa (Maopo) (Society Islands) had the highest levels of all of the essential amino acids, while Ahani and Mahani (Society Islands) and Uto ni viti (Fiji) had significantly lower protein quality. When the data were expressed as a percentage of total protein, hybrids had a significantly higher content of tyr than the A. altilis cultivars evaluated (Figure 3-2a). When the data were expressed on a dry weight basis, met and tyr were significantly higher in the hybrids than A. altilis cultivars. The hybrids also tended to contain more of other amino acids, but these differences were not statistically significant in our sample size (Figure 3-2b). 65 Figure 3-1 Breadfruit (Artocarpus altilis) and hybrids (A. altilis × A. mariannensis) essential amino acid content (mg/g protein). N=9 for each cultivar 66 Figure 3-2 a Figure 3-2 b Figure 3-2 Comparisons of essential amino acid content between breadfruit (Artocarpus altilis) and hybrids (A. altilis × A. mariannensis) based on protein weight (a) (N=39×9 for breadfruit, N=8×9 for hybrids) and dry tissue weight (b) (N=41×9 for breadfruit, N=8×9 for hybrids). Comparisons significant at the 0.05 level are indicated by *. Bars represent the standard error of the mean over individual species * *0102030405060708090His Thr Tyr Val Met Lys Ile Leu Phe Trpmg/g ProteinEssential Amino AcidArtocarpus altilis Artocarpus altilis x. A. mariannensis* ** *00.511.522.533.54His Thr Tyr Val Met Lys Ile Leu Phe Trpmg/g Dry tissueEssential Amino AcidArtocarpus altilis Artocarpus altilis x. A. mariannensis 67 3.3.2. Comparison of essential amino acids between commercial breadfruit and other staples Detailed amino acids profiles for commercial breadfruit cultivars, Ma’afla, Ulu fiti, Yellow, Piipiia, white, and Puua were summarized in Table 3-3. When compared to other staples, Ma’afala had the highest total essential amino acid content as a proportion of the total protein (>568 mg/g protein; Figure 3-3). Ma’afala was especially rich in ile (79.3 mg/g protein) and phe+tyr (149.9 mg/g protein), which were both ~2 to ~4 times higher than other staple crops, and leu (168.6 mg/g protein), which was 1/3–4 times higher than other staples. Ulu fiti had a total essential amino acid (325.1 mg/g protein) that was most similar to potato and higher than cassava and sweet potato. Based on fresh weight, the total essential amino acid contents in Ma’afala (1071.5 mg/100 g fresh tissue) and Piipiia (889.2 mg/g fresh tissue) were higher than in non-grain tropical staples, such as potato, sweet potato, cassava, banana, taro, and yam (Figure 3-4). Ma’afala (1071.5 mg/100 g fresh tissue) contained total essential amino acid that was 1.6 times higher than that of potatoes and ~2.6 times higher than that of sweet potatoes, cassava, or banana. Yellow (538.5 mg/100 g fresh tissue) and Ulu fiti (489.4 mg/100 g fresh tissue) had higher total essential amino acid contents than cassava, sweet potato, and banana. 68 Table 3-3 The summary of amino acid content in commercially available breadfruit cultivars (Artocarpus altilis and A. altilis x A. mariannensis): Ma’afala, Yellow, White, Piipiia, Puaa, and Ulu fiti Amino acid Mg/g based on Ma’afala Yellow White Piipiia Puaa Ulu fiti Ala Average Dry weight 1.20a,b 0.90b,c 0.33d 0.89b,c 0.65c,d 1.42a Protein weight 36a 17b,c 8c 22b 17b,c 25b SE 0.18 0.29 0.11 0.15 0.10 0.10 Arg Average Dry weight 1.22a 0.70b 0.43b 0.72b 0.42b 1.29a Protein weight 37a 13c 11c 18b,c 11c 23b SE 0.18 0.16 0.08 0.10 0.05 0.10 Asn Average Dry weight 3.05b 2.54b 1.25c 1.99b,c 1.12c 5.00a Protein weight 92a 48b 31b 50b 29b 89a SE 0.41 0.64 0.26 0.23 0.20 0.54 Asp Average Dry weight 2.49b 2.09b,c 1.06d 1.46c,d 0.67d 4.05a Protein weight 76a 39b 26b,c 36b,c 18c 72a SE 0.38 0.40 0.22 0.18 0.07 0.46 Glu Average Dry weight 2.34a 1.35b,c 0.76c 2.02a,b 0.97c 1.89a,b Protein weight 71a 25c 19c 50a,b 26c 34b,c SE 0.54 0.30 0.14 0.37 0.13 0.14 Gly Average Dry weight 1.03a 0.49b 0.35b 0.53b 0.41b 0.99a Protein weight 31a 9c 9c 13b,c 11c 18b SE 0.13 0.12 0.06 0.10 0.06 0.11 69 Amino acid Mg/g based on Ma’afala Yellow White Piipiia Puaa Ulu fiti His Average Dry weight 0.70a 0.42b 0.25b 0.41b 0.25b 0.80a Protein weight 21a 8c 6c 10b,c 7c 14b SE 0.09 0.10 0.05 0.06 0.03 0.06 Ile Average Dry weight 2.62a 1.58b 0.98b 1.56b 0.88b 2.72a Protein weight 79a 30b,c 24c 39b,c 23c 49b SE 0.40 0.38 0.17 0.23 0.10 0.28 Leu Average Dry weight 5.56a 2.68b 1.72b 2.74b 1.73b 4.78a Protein weight 169a 51c 42c 69b,c 46c 85b SE 0.68 0.65 0.29 0.38 0.20 0.43 Lys Average Dry weight 1.30a 0.92a,b 0.53b,c 0.83b,c 0.42c 1.28a Protein weight 39a 17b,c 13b,c 21b,c 11c 23b SE 0.24 0.22 0.10 0.12 0.05 0.13 Met Average Dry weight 0.25a 0.11c 0.07c 0.13b,c 0.10c 0.20a,b Protein weight 8a 2b 2b 3b 3b 4b SE 0.04 0.04 0.02 0.02 0.01 0.02 Phe Average Dry weight 4.77a 2.60b 1.57b 2.49b 1.56b 4.46a Protein weight 145a 49c 38c 62b,c 41c 80b SE 0.60 0.64 0.27 0.34 0.20 0.40 Pro Average Dry weight 0.41a 0.26b 0.13b 0.26b 0.12b 0.47a Protein weight 13a 5b,c 3c 7b,c 3c 8b 70 Amino acid Mg/g based on Ma’afala Yellow White Piipiia Puaa Ulu fiti SE 0.10 0.07 0.02 0.03 0.02 0.03 Ser Average Dry weight 1.12a 0.69b 0.29c 0.62b,c 0.43b,c 1.13a Protein weight 34a 13b,c 7c 15b,c 11c 20b SE 0.17 0.16 0.07 0.12 0.05 0.08 Thr Average Dry weight 1.22a 0.70b 0.35b 0.68b 0.39b 1.14a Protein weight 37a 13b,c 9c 17b,c 10c 20b SE 0.20 0.16 0.08 0.10 0.04 0.08 Trp Average Dry weight 0.11a,b 0.07b,c 0.06c 0.08a,b,c 0.04c 0.12a Protein weight 3a 1b 1b 2b 1b 2a,b SE 0.03 0.02 0.01 0.02 0.01 0.01 Tyr Average Dry weight 0.17b 0.13b,c 0.04c 0.13b,c 0.04c 0.34a Protein weight 5a,b 2c 1c 3b,c 1c 6a SE 0.05 0.04 0.01 0.02 0.01 0.06 Val Average Dry weight 2.04a 1.19b,c 0.59c 1.29b 0.76b,c 2.35a Protein weight 62a 22c,d 14d 32b,c 20c,d 42b SE 0.30 0.32 0.16 0.19 0.09 0.20 Means with the same letter are not significantly different. N=9. SE represents the standard error of the mean over individual cultivar. 71 Figure 3-3 Comparison of essential amino acid content between commercially available breadfruit cultivars (Artocarpus altilis and A. altilis x A. mariannensis): Ma’afala, Yellow, White, Piipiia, Puaa, and Ulu fiti and other staples based on protein weight. Essential amino acids data for other staples listed is from the Food and Agriculture Organization of the United Nations (FAO, 1981) 0100200300400500600Essential amino acid content (mg/g protein)StaplesHis Ile Leu Lys Met Phe+Tyr Val Thr Trp 72 Figure 3-4 Comparison of essential amino acid content between commercially available breadfruit cultivars (Artocarpus altilis and A. altilis x A. mariannensis): Ma’afala, Yellow, White, Piipiia, Puaa, and Ulu fiti and other tropical staples based on fresh tissue weight. Essential amino acids data for other staples listed is from the Food and Agriculture Organization of the United Nations (FAO, 1981) 3.4. Discussion Children and infants usually have a higher demand for essential amino acids (WHO, 2007). Children who do not have access to adequate protein sources or essential amino acids in their diets are underweight leading to serious health consequences (WHO, 2009). In 2004, about 20% (112 million) of preschool children 020040060080010001200Essential amino acid content (mg/100g fresh tissue)Tropical StaplesHis Ile Leu Lys Met Phe+Tyr Thr Trp Val 73 were underweight, resulting in 2.2 million child deaths and many other long-term developmental problems. Developing countries experienced most of the underweight cases with almost half of the deaths from this cause occurring in Africa and over 800,000 deaths in Southeast Asia (WHO, 2009). In the daily diet, staples are consumed in such quantities that they constitute a dominant proportion of nutrient intake, including protein intake. Corn, wheat, and rice are the most common staples that comprise two-thirds of the world’s energy intake (FAO et al., 2012). However, most cereals have poor protein quality and are low in tryptophan (especially maize) and/or lysine (especially wheat) (WHO, 2007). People usually consume meat, fruit, vegetables, and other dairy products as a supplementary intake for essential amino acids, but these options are not always affordable especially for undernourished populations (WHO, 2007; 2009). In addition, 349 million undernourished people (nearly 50% of the world’s starving population) are found near the equator (FAO et al., 2012). Production of typical staple crops, such as wheat and corn, may be limited by the warm, wet climate and absence of winter freeze that can allow the proliferation of pathogenic microbes. Therefore, a suitable affordable and nutritious alternative staple is critical for improving food security in the tropical regions. Grain crops, such as maize, rice and wheat, are the most common staples in the world (Lancaster and Coursey, 1984). However, in tropical countries, non-grain staples such as cassava, potato, sweet potato, banana, taro, yam, and breadfruit provide the dietary base for 500-700 million people (Lancaster and Coursey, 1984). The overall goal of our research was to determine whether a diet rich in breadfruit could provide adequate protein quality for food security in these regions. 74 Previous research has shown that 60% breadfruit with 40% soy flour in a weaning diet for children from 1 to 3 years old can supply the recommended overall dietary nutritional allowances within the tolerably low anti-nutrient levels (Ijarotimi and Aroge, 2005 ), but protein quality was not assessed. In our study, a full spectrum of essential amino acids was found in breadfruit (both A. altilis and hybrids). This finding is consistent with the previous study (Golden and Williams 2001). Significant difference was observed between cultivars. Breadfruit is especially rich in phe, leu, ile, and val. Quantification of met and trp may have been underestimated due to the destruction of the structure during the hydrolysis process (Pickering and Newton, 1990). Cysteine was not quantified in this study because of limitations of the analytical technique. The cultivar Ma’afala had the highest essential amino acid content based on both dry weight and protein weight (Table 3-3 ) and was the highest protein variety found in the earlier study (Jones et al., 2011a). Ma’afala contains a higher percentage of the essential amino acids than normally found in soybean, indicating that breadfruit cultivars can have better protein quality than soy. A typical breadfruit based main dish usually uses one mature fruit of an average weight of 1.2 kg (HHFN and NTBG, 2012). I estimate that a 500 g Ma’afala or Ulu Fiti could provide a significant contribution toward the essential amino acid requirement of a preschool child weighing 20 kg (Table 3-4). Similarly, these cultivars contribute significantly toward meeting the nutritional requirements of a 60 kg adult (Table 3-4). 75 Table 3-4 Nutritional value of commercially available breadfruit cultivars (Artocarpus altilis and A. altilis × A. mariannesis): Ma’afala, Yellow, White, Piipiia, Puaa, and Ulu fiti Daily requirement are from the World Health Organization (WHO 2007) mg/500 g fresh breadfruit Requirement per day Ma’afala Yellow White Piipiia Puaa Ulu fiti mg/kg per preschool kid mg/20kg per preschool kid mg/kg per adult mg/60kg adult His 200 108 64 195 67 100 - - 10 600 Ile 749 404 226 668 259 373 27 540 20 1200 Leu 1593 714 450 1167 459 631 54 1080 39 2340 Lys 372 215 109 313 141 217 45 900 30 1800 Met 71 35 25 46 18 24 22 440 10 600 Phe+Tyr 1410 681 409 1173 428 641 40 800 25 1500 Thr 349 178 101 279 100 166 23 460 15 900 Trp 32 20 10 30 15 16 6 128 4 240 Val 581 338 196 575 157 279 36 720 26 1560 76 3.5. Summary The current study analyzed 49 breadfruit cultivars for their amino acid profile using HPLC based amino acid analysis. The results showed that breadfruit contains all the essential amino acids and is especially rich in phenylalanine, leucine, isoleucine, and valine. Individual essential amino acid profiles were generated for each cultivar, and cultivar differences were compared. Ma’afala contained significantly higher total essential amino acid content (568 mg/100g protein) than other varieties and higher-quality protein than staples such as wheat (336 mg/100g protein), corn (413 mg/100g protein), rice (374 mg/100g protein), potato (326 mg/100g protein), soybean (443 mg/100g protein), and yellow pea (366 mg/100g protein). Consumption of 500 g Ma’afala can contribute significantly toward meeting the daily essential amino acid requirement. 77 Chapter 4. Breadfruit Protein Digestibility Analysis Using an in Vitro Human Digestion Model 4.1. Synopsis Protein digestibility is an important part of protein quality evaluation (Blackburn and Southgate, 1981). The essential amino acid profile can provide a good prediction of protein quality, but in practice, the digestibility determines whether a protein is high quality or not (Blackburn and Southgate, 1981). Human digestion is a complex process and in the past two decades there have been many attempts to model this process. In vivo feeding methods, using animals or humans, usually provide the most accurate results, however, they are expensive and time consuming—sometimes even impossible to conduct. In principle, in vitro digestion models provide a useful alternative (Hur et al., 2011). One stage in vitro digestion models usually gave lower protein digestibility than in vivo studies, but two or more stage in vitro digestion, generally, is found to be highly correlated (r>0.8) with in vivo rat true fecal nitrogen digestibility, especially when analyzing plant protein sources (Butts et al., 2012). To our best knowledge, there is no study related to the determination of breadfruit protein digestibility using an in vitro digestion model. 4.1.1. Objectives The objective of this study was to determine the protein digestibility of Ma’afala flour in comparison to commercial wheat flour using a multi stage enzyme digestion model. 78 4.2. Materials and Method 4.2.1. Reagents Multi-stage enzyme digestion model Reagents used for digestion model were: urea (BioReagent Grade for molecular biology, suitable for cell culture; Sigma-Aldrich, St. Louis, MO), α-amylase from human saliva (Type XIII-A, lyophilized powder, 300-1500 units/mg protein, 1 KU; Sigma-Aldrich), pancreatin from porcine pancreas (4 x USP; Sigma-Aldrich), bile bovine (dried, unfractionated; Sigma-Aldrich), BSA (bovine serum albumin) (heat shock fraction, protease free, fatty acid free, essentially globulin free, pH=7, ≥98%; Sigma-Aldrich), pepsin from porcine gastric mucosa (lyophilized powder, 3200-4500 units/mg protein; Sigma-Aldrich), KSCN (ReagentPlus, ≥99.0%; Sigma-Aldrich), KH2PO4 (reagent, Caledon Laboratories Ltd., Georgetown, Ont), Na2SO4 (≥99.0%, plant cell culture tested; Sigma-Aldrich), NH4Cl (cell culture tested; Sigma-Aldrich), NaOH (reagent grade, ≥98%; Sigma-Aldrich), HCl (37%; Sigma-Aldrich), NaCl (small, white crystal; Fisher Scientific, Ontario, Canada), KCl (certified ACS, crystalline; Fisher Scientific), NaHCO3 (Fisher Scientific), CaCl2 • 2H2O (certified ACS, reagent grade, Fisher Scientific), MgCl2 (bioreagents; Fisher Scientific), and NaH2PO4 • H2O (reagent grade, AnaChemia Chemicals, New York, USA). Bioassays HEPES (fine white crystals, bioreagents; Fisher Scientific), Tween 20 (PhytoTechnology Laboratories®, Shawnee Mission, KS), BCA (bicinchoninc acid) protein assay kit (Thermo Fisher Scientific), Modified Lowry Protein Assay Kit (Thermo 79 Scientific), bovine serum albumin protein standard solution (Thermo Scientific). 4.2.2. Sample preparation Breadfruit (cultivar: Ma’afala, Artocarpus altilis) fruits (19 fruits) were harvested from a single 4-year-old-tree grown from commercial micro-propagation at the McBryde Garden, Kauai, HI (21°54’29.47°N; 159°30’41.45°W). Fruit were harvested when mature, peeled, cored and sliced with a mandolin to 6.35 mm slices. Breadfruit slices were dried overnight at 115°C in an Excalibur Dehydrator to complete dryness and shipped to University of British Columbia Okanagan campus. Flour was prepared by grinding dried breadfruit with a burr-style coffee grinder (Bunn, Illinois, USA). Wheat flour (all purpose, Robin Hood™) was purchased from a local supermarket. 4.2.3. In vitro digestion model to mimic human digestion The in vitro digestion model for digesting breadfruit and wheat was modified based on the previous methods published by Kiers et al., 2000; Tenore et al., 2013; Raiola et al., 2012. The digestion process was divided by mouth digestion, stomach digestion, and intestinal digestion (Table 4-1; Figure 4-1). Mouth digestion was mimicked by mixing 6 g of cooked (water boiled) flour with 6 mL artificial saliva in a 50 mL centrifuge tube (Corning Incorporated, New York, USA). The pH of the solution was adjusted to 6-7 with HCl (1N), using a pH meter (VWR International, Pennsylvania, USA). The solution was incubated at 37°C for 5 min in an incubator (Innova®44, Eppendorf, Connecticut, USA). The solution was then mixed with 12 mL pepsin solution. The pH of the mixture was adjusted to 2-4 with HCl (6N). The mixture was incubated at 37°C and shaken consistently at 300 RPM for 2 hours. The intestinal 80 digestion was performed by adjusting the solution pH to 7.5 with NaOH (1 N) and then mixing the solution with 12 mL of pancreatic solution and 6 mL of bile solution. The solution was incubated at 37°C and shaken consistently at 300 RPM for 2 hours. The compositions of saliva, pepsin solution, pancreatic solution and bile solution were listed in supplementary material. The digestion samples were adjusted to pH 7.5. The digestion extracts were stored at -80°C before analysis. A set of digestion was conducted following the same digestion process (Figure 4-1) in absent of flour samples to obtain a digestive enzyme solution that contains all the enzymes and buffers used in the process. Figure 4-1 A Schematic representation of the in vitro digestion model 6 g of cooked breadfruit/wheat flour Breadfruit/wheat digestion extracts stored at -80 °C Measured total protein content after digestion Added 12 mL of pancreatic solution and 6 mL bile solution 2 hrs shaking at 300 RPM at 37 °C 2 hrs shaking at 300 RPM at 37 °C Added 12 mL pepsin solution Added 6 mL saliva solution 5 min shaking at 300 RPM at 37 °C Intestinal digestion pH=7.5 Stomach digestion pH=2-4 Mouth digestion pH=6-7 Measured total protein content before digestion 81 Table 4-1 The composition of saliva, gastric solution, duodenal solution, and bile solution used in the multi-stage enzyme digestion model Saliva Gastric solution Duodenal solution Bile solution Item g/l Item g/l Item g/l Item g/l KCl 1.792 NaCl 5.500 NaCl 0.168 NaCl 10.518 KSCN 0.400 NaH2PO4 0.533 NaHCO3 0.081 NaHCO3 11.570 NaH2PO4 1.776 KCl 1.649 KH2PO4 0.002 KCl 0.753 Na2SO4 1.140 CaCl2·2H2O 0.799 KCl 0.014 Urea 0.500 NaCl 0.600 NH4Cl 0.612 MgCl2 0.001 CaCl2·2H2O 0.444 NaHCO3 3.388 Urea 0.170 Urea 0.200 BSA 3.600 Urea 0.400 BSA 2.000 CaCl2·2H2O 0.400 Bile 60.000 α-amylase 0.002 Pepsin 5.000 BSA 2.000 Pancreatin 18.000 BSA=bovine serum albumin 4.2.4. Protein determination in the flours and digestion extracts Protein was extracted from the flour following the method published by Jones et al. (2011a). First, 10 mg flour was weighed into a 1.5 mL microcentrifuge tube (Fisher Scientific, Ottawa, ON) with 0.5 mL protein extraction buffer (20 mM HEPES, 150 mM NaCl, 0.3% Tween 20). The mixture was vortexed and sonicated for 15 min at room temperature (FS20, Fisher Scientific). The tubes were centrifuged for 10 min at 13,000 RPM (Galaxy 16DH; VWR, Westchester, PA). The supernatant was saved for the protein determination of flours. The protein content of flours (wheat and breadfruit, 3 replicates each) and 82 digestion extracts (digestive enzyme solution, wheat digestion, and breadfruit digestion, 3 replicates each) were first determined by BCA (bicinchoninic acid) protein assay (Pierce) following standard kit instructions. 25 µL of the protein extracts from the flour and each bovine serum albumin (BSA) protein standard solution (0, 0.125, 0.25, 0.5, 1.0, 1.5, 2.0 mg/mL) were plated into a 96 microplate well in duplicates (BD Biosciences, Mississauga, Canada) with 200 µL BCA working reagent (1:50, v/v, Reagent A/Reagent B). The plate was gently shaken for 30 seconds and incubated at 37°C for 30 min. Absorbance was measured at 562 nm using a Synergy HT microplate reader (Biotek, Winooski, VT). The protein content of digestion extracts was calculated by comparing to a standard curve of varying concentrations of BSA standard solution. The protein content of digestion extracts was measured using the same protocol except a 1:5 dilution of the extract in 0.9% NaCl was performed before measurement. This experiment was repeated twice independently. An orthogonal method for protein quantification was used. A modified Lowry Protein Assay Kit (Fisher) using standard protocols quantified protein in 40 µL aliquots of each of the samples by comparison to the same BSA protein standard solutions. Samples and standards were mixed with 200 µL modified Lowry reagents and plated in a 96-well microplate in duplicates at room temperature for 10 min followed by another 30 min incubation with 20 µL 1X Folin-Ciocalteu Reagent at room temperature. The absorbance was measured at 750 nm using the same microplate reader. The protein content was calculated by direct comparison of samples to the standard curve of varying concentrations of BSA standard solution. This experiment was repeated twice independently. 83 4.3. Results Before digestion, the protein content of wheat flour was 5.3% (modified Lowry assay), or 3.8% (BCA assay) (Figure 4-2a). Breadfruit flour had a protein content of 6.2 % (modified Lowry assay) or 4.5% (BCA assay). About 87% (modified Lowry assay) or 89% (BCA assay) of the breadfruit protein was fully digested in the in vitro digestion model while 79% (modified Lowry assay) or 71% (BCA assay) of the wheat protein was fully digested (Figs. 4-2a & b). After the digestion reactions, there was significantly more intact protein in the wheat digestion extract than the breadfruit confirming that more of the breadfruit protein could be digested (Figure 4-2b). Fig 4-2 a Protein content (mg/g flour weight)Wheat before digestionWheat after digestionBreadfruit before digestionBreadfruit after digestionWheat before digestionWheat after digestionBreadfruit before digestionBreadfruit after digestion020406080**** 84 Fig 4-2 b Figure 4-2 Protein content in wheat and breadfruit flour before and after digestion (a) and digestion extracts (b) by BCA and Modified Lowry Assays (n=3). * represents significant difference at α=0.05. ** represents significant difference at α=0.01. *** represents significant difference at α=0.001, using two sample t-test or one-way ANOVA with Tukey-Kramer Honest Significant Difference (HSD) test. Bar represents the standard error of 6 replicates within each treatment 4.4. Discussion In order to meet protein requirements in the diet and provide adequate consumption of essential amino acids, staple foods must be digested and absorbed through the gut (Latham 1997). The evaluation of protein quality is primarily focused Protein content (mg/g flour weight)Digestive enzyme solutionWheat digestionBreadfruit digestionDigestive enzyme solutionWheat digestionBreadfruit digestion051015BCA assay Modified Lowry assay*** ***** 85 on two aspects: the overall protein content/amino acid profile and the protein digestibility/amino acid availability. Our previous research has established the protein and amino acid content of breadfruit flours. The differences in overall protein content of wheat and breadfruit flours in the literature and in our assays were not substantial. Wheat flour has a protein content of about 10% based on the USDA index (USDA 2014) but analysis of commercial wheat flours varies depending on analysis methods (Knight and Chambers 2003; Moore et al., 2010). The breadfruit cultivar, Ma’afala, used in this study has a reported protein content of 7.6% (Jones et al., 2011a) but varies slightly between batches and years. In this study, protein content for both flours was less than the value reported in the literature, and Ma’afala flour had higher protein content than wheat flour. This project showed that Ma’afala had higher total essential amino acid content (568 mg/g protein) than other varieties or wheat flour (336 mg/g protein). Our current objective was to establish breadfruit flour digestibility using in vitro assays in comparison to wheat. Breadfruit showed a higher protein digestibility than wheat protein in the in vitro model. Wheat digestibility can be problematic as the storage proteins gluten and lectin may be undigested in the gut but these proteins are not found in breadfruit flours (de Mejia and Prisecaru, 2007; de Punder and Pruimboom, 2013; Simonato et al., 2001; Ijarotimi and Aroge, 2005). 4.5. Summary Breadfruit showed a higher protein digestibility than commercial wheat flour using an in vitro multi-stage enzyme digestion model. 86 Chapter 5. Effects of Breadfruit Digestion on Human Colon Epithelial Cells Using an In Vitro Cell Model 5.1. Synopsis Human intestinal cells, especially the epithelium, shoulder the responsibility to absorb nutrients and serve as a barrier to bacteria, pathogens, and other antigens. Damage to the epithelium, which is usually caused by imbalanced apoptotic cell death, is thought to be responsible for diseases of the gastrointestinal tract (Lee, 1993), therefore cytotoxicity/cell viability is a critical indicator of epithelial health. Cytokines secreted by human epithelial cells play a critical role in mucosal and systemic immunity. Although food is known to be a factor that alters intestinal immune response (Lied et al., 2011), the extent to which digested food regulates cytokine formation through epithelial cells is poorly understood. Caco-2 cells are a human intestinal epithelial cell line that are widely used to investigate the interaction between food substances and the intestinal epithelium (Shimizu 2010). Cell models can provide larger screening capacity at lower cost than animal models (Langerholc et al., 2011). To our best knowledge, no study has ever been done to evaluate the impact of breadfruit digestion on intestinal cells. 5.1.1. Objectives The first objective of this study was to determine the cytotoxicity of breadfruit digestion to the human colon epithelial cells in comparison to wheat digestion. By examining the viability of the cells after digestion treatment, impact of the breadfruit digestion to colon epithelial morphology was compared to the impact caused by the wheat digestion. The second objective of this study was to determine the immune 87 response of the human intestinal cells to breadfruit and wheat digestions quantified as changes in specific cytokines including: (a) the anti-inflammatory cytokines: interleukin 4 (IL-4), interleukin 10 (IL-10); (b) the pro-inflammatory cytokines: tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), inducible nitric oxide synthase (iNOS); (c) pleiotropic cytokine: interleukin 6 (IL-6); and (d) chemokines: monocyte chemoattractant protein-1 (MCP-1) and interleukin 8 (IL-8). Overall, our results will quantify the effects of breadfruit digestion on human colon epithelial cells. 5.2. Materials and Method 5.2.1. Reagents Caco-2 cell Culture Materials used for Caco-2 cell culture were: HEPES buffered Dulbecco’s modified Eagle’s medium (DMEM) (high glucose, 4500 mg/L glucose, no L-glutamine, no sodium pyruvate; Thermo Fisher Scientific, Manassas, USA), sodium pyruvate (100 mM solution; Corning Cellgro, Mediatech Inc., Manassas, VA), penicillin-streptomycin (100X, 10000 µg/mL; Corning cellgro, Mediatech Inc) , L-alanyl-L-glutamine were purchased (100X, liquid, Mediatech Inc.), FBS (fetal bovine serum) (Standard; Gibco® Life technologies, Thermo Fisher Scientific), phosphate buffered saline (PBS) (without calcium or magnesium; Lonza, Walkersville, MD) nonessential amino acid solution (100X, 0.1 µm sterile filtered; Thermo Fisher Scientific), trypsin (1X, 0.25% trypsin in HBSS without calcium or magnesium, Porcine Parvovirus Tested; Corning Cellgro, Mediatech Inc.) 88 Bioassays Reagents employed in the assays were: anhydrous ethyl alcohol (molecular grade; Commercial Alcohols, Ontario, Canada), chloroform and isopropyl alcohol (HPLC graded; OmniPur®, EMD Millipore Corporation, Billerica). RiboZol (biotechnology grade; Amresco, Ohio, USA), trypan blue solution (0.4% w/v in PBS; Corning Cellgro, Mediatech Inc.), iScript cDNA synthesis kits (Bio-Rad Laboratories, Ontario), and SsofastTM EvaGreen Supermix (Bio-Rad Laboratories), and nuclease-free water (Integrated DNA technologies, Coralville, USA). Treatment applications Other materials used in this study were: lipopolysaccharide (LPS) from Escherichia coli 0111:B4 (γ-irradiated, BioXtra, suitable for cell culture; Sigma-Aldrich), interleukin 1 beta (IL-1β) human (animal-component free, recombinant, expressed in E. coli, ≥98% (SDS-PAGE), ≥98% (HPLC); Sigma-Aldrich). Human primers including: tumor necrosis factor alpha (TNF-α), (interferon gamma) IFN-γ, monocyte chemoattractant protein-1 (MCP-1), inducible nitric oxide synthase (iNOS), interleukin 4 (IL-4), interleukin 6 (IL-6), interleukin 8 (IL-8), interleukin 10 (IL-10) and 18S rRNA (18S ribosomal RNA) were purchased from Integrated DNA Technologies (Coralville, USA). 5.2.2. Caco-2 human epithelial colorectal adenocarcinoma cells Cells were obtained from the American Type Culture (ATCC® HTB-37TM) and cultured using established protocols. Cells were cultured in a T-75 flask (Greiner Bio-one, Canada) with standard growth media containing HEPES buffered Dulbecco’s 89 modified Eagle’s medium (DMEM) with 4.5 g/L glucose, 1% nonessential amino acid, 20% fetal bovine serum (FBS), 2% penicillin-streptomycin, 2% L-alanyl-L-glutamine, and 1% sodium pyruvate. Cells were grown in a controlled environment with a temperature of 37°C and a humidified atmosphere of CO2 /air (5/95, %) in an Air-Jacketed CO2 Symphony incubator (VWR International, Pennsylvania, USA). Cells were passaged every 7 days by trypsinisation. Trypsinisation was performed by incubating PBS washed cells with 3 mL trypsin for 4 minutes at 37°C. The trypsin solution containing cells was deactivated by 9 mL growth media. The solution was centrifuged at 234 g for 2 min. The cells were re-suspended in 6 mL growth media and counted by standard trypan blue staining assay (1:1, v/v, trypan blue/re-suspended cell solution) using a hemocytometer. For the generation, 800,000 cells were sub-cultured into a new T-75 flask with 20 mL growth media. Cells used for stimulation were within generation 15 and 25. Cells were plated into 24 transwells (Greiner Bio-one, Canada) (40,000 cells per well) with the growth medium and they grew until reached 80% confluence. The entire experiment was performed in triplicate. 5.2.3. Digestion extracts preparation The preparation of digestive enzyme solution, wheat digestion and breadfruit digestion was described in full details in Chapter 4.2.1-4.2.3. The samples were centrifuged and filtered using an Ultrafree® MC centrifugal filter (Millipore Corporation, USA) at 13,000 RPM for 10 min before applying to Caco-2 cells. 90 5.2.4. Effects of digestion extracts on Caco-2 cell viability Caco-2 cells were incubated for 4 hours with four different concentrations (1%, 5%, 10%, and 50%) of three different digested extracts (digestive enzyme solution, wheat digestion, and breadfruit digestion) in the standard growth media. After 4 hours, 200 µL trypsin was added into each well and the cells were incubated with trypsin for 2 min at 37°C in a SymphonyTM incubator (VWR International; Pennsylvania, USA). A gentle shake was applied to the well to ensure complete lifting of the cells. 200 µL standard growth medium was added into each well to deactivate trypsin. An aliquot of 400 µL of cells was aseptically transferred to a 1.5 mL clear Eppendorf tube and mixed with an equal volume of 0.4% (w/v) trypan blue solution in PBS. Cell counts were recorded using a dual-chamber hemocytometer (QiuJing®, Guangzhou, China) and a light microscope (Olympus, Ontario, Canada). Viable and nonviable cells were counted separately. The mean of four independent cell counts were pooled for analysis. 5.2.5. Effects of LPS and/or IL-1β stimulation on Caco-2 cells Caco-2 cells were stimulated with LPS, IL-1β, and LPS plus IL-1β for 4, 8 and 24 hours. LPS used for the stimulation was made in the following way: 1 mg LPS was re-suspended with 1 mL nuclease-free water. 0.4 µL suspended LPS was mixed with 9.6 µL growth medium and used for the stimulation. 10 µg IL-1β was prepared by re-suspended 100 µL nuclease-free water. 0.4 µL suspended IL-1β was mixed with 9.6 µL PBS and used for the stimulation. RNA extraction was performed on the Caco-2 cells using RiboZol, following the 91 manufacturer’s instruction. 400 µL RiboZol was added into each well and incubated with the cells at room temperature for 5 min. The RiboZol solution containing cells was transferred into a 1.5 mL tube (Fisher Scientific, Ontario, Canada) with 50 µL chloroform. The mixture was shaken vigorously by hand and incubated at room temperature for 2-3 min. After incubation, the samples were centrifuged at 12,000 g for 15 min at 4°C. The aqueous phase was transferred into a new tube 1.5 mL with 200 µL 100% isopropanol. The samples were incubated at -80°C for 20 min and then centrifuged at 12,000 g for 10 min at 4°C. The supernatant was removed and the RNA pellet was washed by 400 µL 75% ethanol. The samples were centrifuged at 7,500 g for 5 min at 4°C. The supernatant was removed and the RNA pellet was air dried at room temperature for 10 min. The RNA pellets were re-suspended in 50 µL nuclease free water and incubated in a hot water bath (55°C) for 15 min. The concentration of the RNA samples was measured by a NanoDrop 2000c UV-Vis Spectrophotometer (Thermo Fisher Scientific, Manassas, USA). Based on RNA concentration, 1 to 2 µg of RNA was reversed transcribed using an iScript cDNA synthesis kit by following the manufacturer’s instructions. The mixture contained RNA samples, nuclease free water, 4 µL 5x iScript reaction mix and 1 µL iScript reverse-transcriptase. The mixture was run through a standard cDNA synthesis cycle, including 25°C for 5 min, 42°C for 30 min, 85°C for 5 min and 4°C in a C1000 TouchTM Thermal Cycler (Bio-Rad Laboratories, Ontario, Canada). cDNA samples were diluted in 1:10 in nuclease free water. An SsofastTM EvaGreen Supermix was used to prepare qPCR mixture, following the manufacturer’s instruction. The qPCR mixture contained 5 µL Ssofast 2x Mix, 0.2 µL 5 µM forward 92 primer, 0.2 µL 5 µM reverse primer, 1 µL diluted cDNA and 3.6 µL nuclease free water. The qPCR mixture was plated in duplicates into a 96 MultiplateTM PCR plates (Bio-Rad Laboratories, Ontario, Canada) and detected by CFX96 Touch real time detection system (Bio-Rad Laboratories, Ontario, Canada). The qPCR run cycle contained enzyme activation at 95°C for 30 s (1 cycle), denaturation at 95°C for 5 s (55 cycle), annealing at 58°C for 5 s (55 cycle) and melt curve at 95°C for 10 s. The reference gene was 18S rRNA. Gene expression of TNF-α, IFN-γ, MCP-1, IL-10, IL-6, iNOS, IL-8 and IL-4 were examined. Calculations of the expression value were performed in the Bio-Rad CFX manager 3.1 (Bio-Rad Laboratories, Ontario, Canada) using the ΔΔCt method. 5.2.6. Effects of digestion extracts combined with LPS and/or IL-1β stimulations on Caco-2 cells Caco-2 cells were incubated with digestion extracts (digestive enzyme solution, wheat digestion, and breadfruit digestion) combined with different stimulations (non-stimulated, LPS, IL-1β, LPS, and IL-1β) for 24 hours (Table 5-1). RNA extraction, cDNA synthesis, and qPCR analysis process were performed as above. 93 Table 5-1 Experimental design for testing effects of digestion extracts combined with LPS and/or IL1β stimulation on Caco-2 cells (n=3) after 24 hours Block Conc. of stimulations Stimulation Conc. of treatments Treatment 1 - Non stimulated 0% No treatment 1% Digestive enzyme solution Wheat digestion Breadfruit digestion 2 1000 ng/mL LPS 0% LPS only 1% Digestive enzyme solution Wheat digestion Breadfruit digestion 3 100 ng/mL IL 1β 0% IL 1β only 1% Digestive enzyme solution Wheat digestion Breadfruit digestion 4 LPS: 1000 ng/mL, IL 1β: 100 ng/mL LPS+ IL 1β 0% LPS+IL 1β only 1% Digestive enzyme solution Wheat digestion Breadfruit digestion 5.2.7. Primers design and efficiency testing All the primers (Table 5-2) used in this experiment have been designed using Primer-BLAST software (National Center for Biotechnology Information, USA). For each cytokine, the primer set includes a reverse primer and a forward primer. The primers were designed to have a PCR product size range from 70 to 150 bps. The primer melting temperatures were selected between 57°C and 63°C. To ensure primer 94 specificity, all primers must have no more than at least 2 total mismatches to unintended targets, including at least 2 mismatches within the last 5 bps at the 3’ end. Primers with a minimum occurrence of hairpin, self-dimer, hetero dimer were selected using OligoAnalyzer 3.1 software (Integrated DNA technologies, Coralville, USA). Gradient qPCR runs at an annealing temperature range of 50-63°C to test for the best annealing temperature. The primer efficiency was tested by using LinregPCR (Analysis of quantitative RT-PCR data) (Dr. J.M. Ruijter, Academic Medical Centre, and Australia). Table 5-2 RNA sequence, best annealing temperature and primer efficiency for the primers used in the breadfruit in vitro cell model study Primer Forward sequence Reverse sequence Best annealing temp. Efficiency 18S GTAACCCGTTGAACCCCATT CCATCCAATCGGTAGTAGCG 58 °C 100% TNF-α TCTCGAACCCCGAGTGACAA TATCTCTCAGCTCCACGCCA 58°C 100% IL-10 TTCCATTCCAAGCCTGACC CCAAGCCCAGAGACAAGATAAA 58°C 91% IL-6 GAGAGTAGTGAGGAACAAGCC GGTCAGGGGTGGTTATTGC 58°C 92% IL-4 TTCCCCCTCTGTTCTTCCT GTCTGTTACGGTCAACTCGG 58°C 95% iNOS AGCCCTTTACTTGACCTCCT TCCATCTTTCACCCACTTGC 58°C 100% MCP-1 GGCTGAGACTAACCCAGAAAC GAATGAAGGTGGCTGCTATGA 58°C 95% IFN-γ GGGTTCTCTTGGCTGTTACT GAGTTCCATTATCCGCTACATCT 58°C 92% IL-8 GAGACAGCAGAGCACACAAG ACACACAGTGAGATGGTTCC 58°C 100% 95 5.2.8. Statistical analysis All statistical analysis was conducted using JMP® 10.0.0 (SAS Institute, Cary, NC). A series of independent two sample t-test or ANOVA followed by Tukey-Kramer Honest Significant Difference (HSD) tests were conducted to determine if there were significant differences between treatments with a type 1 error rate of 0.05. Graphs were created using GraphPad Prism 5.0 software (GraphPad Software Inc., La Jolla, CA). 5.3. Results 5.3.1. Effects of digestion extracts on Caco-2 cell viability There was no significant difference in the viability of untreated cells and cells treated for 4 hours with digestion extracts (1% of either digestive enzyme solution, wheat digestion or breadfruit digestion) (Figure 5-1a). At higher concentrations (5%) of the digestive enzyme solution without digestions, a significant reduction in the percentage of live cells was observed (Figure 5-1b). Interestingly, the digestions had a mediating effect with 21% increased cell viability with wheat in the digestive enzyme solution and 30% increased cell viability with breadfruit digestions (Figure 5-1a). When the digestion extracts were included at 5% in the cell cultures, breadfruit digestion treated cells had significantly increased viability relative to both the control digestion and wheat (Figure 5-1b). When the digestion extract was included at 10% in the cell culture medium, cell viability was significantly reduced in all treatments (Figure 5-1c). At 50% of digestion extracts in the cell cultures, the breadfruit digestion extract had a significantly higher cell viability (42% higher) than the digestive enzyme solution 96 without flours (Figure 5-1d). Overall, Caco-2 cells exposed to breadfruit digestion extracts had a significantly higher cell viability than cells exposed to the digestive enzyme solution alone. Increasing the amount of any of the dilution extracts significantly reduced the absolute number of viable cells and the 1% digestion extracts was most suitable for comparative studies (Figure 5-2). Figure 5-1 a: Cell viability under 1% treatment 0% digestion1% digestive enzyme solution1% wheat digestion1% breadfruit digestion020406080100Estimated % live cells per mL 97 Figure 5-1 b: Cell viability under 5% treatment Figure 5-1 c: Cell viability under 10% treatment 0% digestion5% digestive enzyme solution5% wheat digestion5% breadfruit digestion020406080100*Estimated % live cells per mLEstimated % live cells per mL0% digestion10% digestive enzyme solution10% wheat digestion10% breadfruit digestion020406080100******** 98 Figure 5-1 d: Cell viability under 50% treatment Figure 5-1 Effects of digestion extracts of wheat and breadfruit on cell viability. a) 1% digestion extracts. b) 5% digestion extracts. c) 10% digestion extract. d) 50 % digestion extracts. Error bars represent the standard error of 3 replicates within each treatment. * represents significant difference at α=0.05, ** represents significant difference at α=0.01, *** represents significant difference at α=0.001, using one-way ANOVA with Tukey-Kramer Honest Significant Difference (HSD) test Estimated % live cells per mL0% digestion50% digestive enzyme solution50% wheat digestion50% breadfruit digestion020406080100********** 99 Figure 5-2 Estimated total number of Caco-2 cells per ml after treatment with digestion extracts for 4 hrs. * represents significant difference at α=0.05,** represents significant difference at α=0.01,*** represents significant difference at α=0.001, using one-way ANOVA with Tukey-Kramer Honest Significant Difference (HSD) test. Bar represents the standard error of 3 replicates within each treatment 5.3.2. Effects of LPS and/or IL-1β stimulations on Caco-2 cells To determine the best methods of stimulating Caco-2 cells for immune responses, LPS and IL-1β were compared to unstimulated cells (Figure 5-3). Caco-2 cells stimulated with LPS had significantly increased MCP-1 and iNOS expression after 8 hours as compared to unstimulated cells (Figure 5-3 a & b). There were no significant differences in the remaining cytokines (IL-4, IL-6, IL-8, IL-10, TNF-α, and IFN-γ) between LPS stimulated cells and unstimulated cells regardless of the TreatmentEstimated total number of Caco-2 cells per mL1% 5% 10%50%0200,000400,000600,000800,0001,000,000Digestive Enzyme solution Wheat Digestion Breadfruit Digestion**** 100 stimulation duration (Figure 5-3 c-g). When IL-1β was used to stimulate the Caco-2 cells, significantly higher MCP-1, TNF-α, and IL-8 expression was observed after 8 and 24 hours (Figure 5-3 a, c, and f) and significantly higher IL-6 expression was observed after 4 and 8 hours (Figure 5-3 e). When the LPS and IL-1β stimulation was applied in unison, a significant increase in iNOS and TNF-α was observed after 4 hours (Figure 5-3 b & c). A significant increase in IL-10 was observed after 8 hours (Figure 5-3 g). Similarly, MCP-1 expression was significantly higher after 4 and 8 hours (Figure 5-3 a), and IL-8 expression was significantly higher at 4, 8, and 24 hour sampling points (Figure 5-3 f). Significant increases in the expression of IL-4 and IL-6 were observed after 24 hours (Figure 5-3 d and e). For the stimulation period studied, mRNA expression of IFN-γ did not show any significant difference among the four different stimulation types (Figure 5-3 h). Figure 5-3 a: MCP-1 production 4 Hours 8 Hours 24 Hours0.00.20.40.60.8****************Stimulation period (h) mRNA expression of MCP-1Unstimulated Cells Cells+LPS Cells+IL1 beta Cells+LPS+IL1 beta 101 Figure 5-3 b: iNOS production Figure 5-3 c: TNF-α production 4 Hours 8 Hours 24 Hours01234****Stimulation period (h)mRNA expression of iNOSUnstimulated Cells Cells+LPS Cells+IL1 beta Cells+LPS+IL1 beta4 Hours 8 Hours 24 Hours0.000.020.040.060.080.20.30.40.5********Stimulation period (h)mRNA expression of TNF alpha******Unstimulated Cells Cells+LPS Cells+IL1 beta Cells+LPS+IL1 beta 102 Figure 5-3 d: IL-4 production Figure 5-3 e: IL-6 production 4 Hours 8 Hours 24 Hours0.00.10.20.30.40.51.01.5 **Stimulation period (h)mRNA expression of IL-4Unstimulated Cells Cells+LPS Cells+IL1 beta Cells+LPS+IL1 beta4 Hours 8 Hours 24 Hours01234*******Stimulation period (h)mRNA expression of IL-6Unstimulated Cells Cells+LPS Cells+IL1 beta Cells+LPS+IL1 beta 103 Figure 5-3 f: IL-8 production Figure 5-3 g: IL-10 production 4 Hours 8 Hours 24 Hours0.000.020.040.060.080.51.01.5*********** ****** *******Stimluation period (h)mRNA expression of IL-8Unstimulated Cells Cells+LPS Cells+IL1 beta Cells+LPS+IL1 beta4 Hours 8 Hours 24 Hours0.00.10.20.30.40.5******Stimulation period (h)mRNA expression of IL-10Unstimulated Cells Cells+LPS Cells+IL1 beta Cells+LPS+IL1 beta 104 Figure 5-3 h: IFN-γ production Figure 5-3 The mRNA expression of cytokines from Caco-2 cells with no stimulation, IL-1β, or LPS+IL-1β stimulation for 4 hrs, 8 hrs, and 24 hrs. (a) MCP-1. (b) iNOS. (c) TNF-α. (d) IL-4. (e) IL-6. (f) IL-8. (g) IL-10. (h) IFN-γ. Error bar represents the standard error of 3 replicates within each treatment.*, **, *** represents significant difference at α=0.05, at α=0.01, and α=0.001 respectively, using one-way ANOVA Tukey-Kramer Honest Significant Difference (HSD) test 5.3.3. Effects of digestion extracts combined with LPS and/or IL-1β stimulations on Caco-2 cells Breadfruit digestion triggered a similar cytokine response on Caco-2 cells as wheat digestion. All eight cytokines were examined, but no significant differences were observed for IL-4, IL-10, IL-8, TNF-α or IFN-γ between wheat digestion treated group and breadfruit digestion treated group (Table 5-3; Figure 5-4, 5-5, 5-6 and 5-7). For digestion extract treated unstimulated cells, 1% breadfruit treated cells had 4 Hours 8 Hours 24 Hours0.00.10.20.30.4246810Stimulation period (h)mRNA expression of IFN gammaUnstimulated Cells Cells+LPS Cells+IL1 beta Cells+LPS+IL1 beta 105 significantly higher MCP-1 expression than wheat-treated cells and digestive enzyme solution treated cells (Figure 5-4 h). When LPS stimulation was applied with 1% digestion extracts, cells exposed to the breadfruit digestive extract had a higher iNOS expression than other groups (Figure 5-5 h). When IL-1β stimulation was applied, the 1% wheat digestion extract stimulated a significant IL-6 response but the breadfruit reduced the IL-6 stimulation (Figure 5-6 h). When the LPS and IL-1β stimulations were combined, the expression of IL-6 production was significantly higher in wheat treated cells than breadfruit treated cells (Figure 5-7 h). 106 Table 5-3 Cytokine response of Caco-2 after 24 hours of breadfruit/wheat digestion treatments under various stimulations Major function Cytokine Non-stimulated LPS stimulated IL 1β stimulated IL 1β+LPS stimulated Anti-inflammatory IL 4 NSD NSD NSD NSD IL 10 NSD NSD NSD NSD Pro-inflammatory iNOS NSD Breadfruit > Wheat NSD NSD TNF α NSD NSD NSD NSD IFN γ NSD NSD NSD NSD Chemokines MCP-1 Breadfruit > Wheat NSD NSD NSD IL 8 NSD NSD NSD NSD Pleiotropic IL 6 NSD NSD Wheat > Breadfruit Wheat > Breadfruit > represents significant higher based on alpha level of 0.05 107 Figure 5-4 a: IL-10 under no stimulation Figure 5-4 b: IL-4 under no stimulation Digestive Enzyme SolutionWheat DigestionBreadfruit Digestion0.00.20.40.6mRNA expression of IL10Digestive Enzyme SolutionWheat DigestionBreadfruit Digestion0.00.51.01.52.0mRNA expression of IL4 108 Figure 5-4 c: iNOS under no stimulation Figure 5-4 d: TNF-α under no stimulation Digestive Enzyme SolutionWheat DigestionBreadfruit Digestion0.00.20.40.60.8 mRNA expression of iNOSDigestive Enzyme SolutionWheat DigestionBreadfruit Digestion0.000.050.100.15mRNA expression of TNF alpha 109 Figure 5-4 e: IFN-γ under no stimulation Figure 5-4 f: IL-8 under no stimulation Digestive Enzyme SolutionWheat DigestionBreadfruit Digestion0.00.51.01.5Absolute mRNA expression of IFN gammaDigestive Enzyme SolutionWheat DigestionBreadfruit Digestion0.000.050.100.15Absolute mRNA expression of IL8 110 Figure 5-4 g: IL-6 under no stimulation Figure 5-4 h: MCP-1 under no stimulation Figure 5-4 Effect of digestive enzyme solution, wheat digestion, and breadfruit digestion on cytokine expression in Caco-2 cells without LPS or IL-1β stimulation for 24 hours. a) IL-4, b) IL 10, c) iNOS, d) TNF-α, e) IFN-γ, f) IL-8,g) IL- 6, h) MCP-1. Error bar represents the standard error of 3 replicates within each treatment. *, ** represent significant difference at α=0.05, α=0.01, respectively, using one-way ANOVA with HSD Test Digestive Enzyme SolutionWheat DigestionBreadfruit Digestion01234Absolute mRNA expression of IL 6Digestive Enzyme SolutionWheat DigestionBreadfruit Digestion0.00.51.01.52.02.5***Absolute mRNA expression of MCP-1 111 Figure 5-5 a: IL-4 production under LPS stimulation Figure 5-5 b: IL-10 production under LPS stimulation LPS Stimulation1% Enzyme Solution+LPS1% Wheat Digestion+LPS1% Breadfruit Digestion+LPS0.00.51.01.5mRNA expression of IL4LPS Stimulation1% Enzyme Solution+LPS1% Wheat Digestion+LPS1% Breadfruit Digestion+LPS0123mRNA expression of IL10 112 Figure 5-5 c: TNF-α production under LPS stimulation Figure 5-5 d: IFN-γ production under LPS stimulation LPS Stimulation1% Enzyme Solution+LPS1% Wheat Digestion+LPS1% Breadfruit Digestion+LPS0123mRNA expression of TNF alphaLPS Stimulation1% Enzyme Solution+LPS1% Wheat Digestion+LPS1% Breadfruit Digestion+LPS0.00.10.20.30.4mRNA expression of IFN gamma 113 Figure 5-5 e: MCP-1 production under LPS stimulation Figure 5-5 f: IL-8 production under LPS stimulation LPS Stimulation1% Enzyme Solution+LPS1% Wheat Digestion+LPS1% Breadfruit Digestion+LPS0.00.51.01.5mRNA expression of MCP-1LPS Stimulation1% Enzyme Solution+LPS1% Wheat Digestion+LPS1% Breadfruit Digestion+LPS01234mRNA expression of IL8 114 Figure 5-5 g: IL-6 production under LPS stimulation Figure 5-5 h: iNOS production under LPS stimulation Figure 5-5 Effect of digestive enzyme solution, wheat digestion, and breadfruit digestion on cytokine expression in Caco-2 cells stimulated with LPS (1000 ng/mL) for 24 hours. a) IL-4, b) IL 10, c) TNF-α, d) IFN-γ, e) MCP-1, f) IL-8, g) IL- 6 h) iNOS. Error bar represents the standard error of 3 replicates within each treatment. * represents significant difference at α=0.05, using one-way ANOVA with HSD Test. LPS Stimulation1% Enzyme Solution+LPS1% Wheat Digestion+LPS1% Breadfruit Digestion+LPS0.00.51.01.5mRNA expression of IL 6LPS Stimulation1% Enzyme Solution+LPS1% Wheat Digestion+LPS1% Breadfruit Digestion+LPS0.00.51.01.52.0***mRNA expression of iNOS 115 Figure 5-6 a: IL-4 production under IL-1β stimulation Figure 5-6 b: IL-10 production under IL-1β stimulation IL 1 beta Stimulation1% Enzyme Solution+IL 1 beta1% Wheat+IL 1 beta1% Breadfruit+IL1 beta0.00.10.20.30.4mRNA expression of IL4IL 1 beta Stimulation1% Enzyme Solution+IL 1 beta1% Wheat+IL 1 beta1% Breadfruit+IL1 beta0.000.050.100.15mRNA expression of IL10 116 Figure 5-6 c: iNOS production under IL-1β stimulation Figure 5-6 d: TNF-α production under IL-1β stimulation IL 1 beta Stimulation1% Enzyme Solution+IL 1 beta1% Wheat+IL 1 beta1% Breadfruit+IL1 beta0.000.020.040.060.080.10mRNA expression of iNOSIL 1 beta Stimulation1% Enzyme Solution+IL 1 beta1% Wheat+IL 1 beta1% Breadfruit+IL1 beta0.00.20.40.60.8mRNA expression of TNF alpha 117 Figure 5-6 e: IFN-γ production under IL-1β stimulation Figure 5-6 f: MCP-1 production under IL-1β stimulation IL 1 beta Stimulation1% Enzyme Solution+IL 1 beta1% Wheat+IL 1 beta1% Breadfruit+IL1 beta0.00.20.40.6mRNA expression of IFN gammaIL 1 beta Stimulation1% Enzyme Solution+IL 1 beta1% Wheat+IL 1 beta1% Breadfruit+IL1 beta0.000.020.040.060.08mRNA expression of MCP-1 118 Figure 5-6 g: IL-8 production under IL-1β stimulation Figure 5-6 h: IL-6 production under IL-1β stimulation Figure 5-6 Effect of digestions on cytokine expression on Caco-2 cells stimulated with IL-1β (100 ng/mL) for 24 hours a) IL-4, b) IL 10, c) iNOS, d) TNF-α, e) IFN-γ, f) MCP-1, g) IL-8, h) IL- 6. Error bar represents the standard error of 3 replicates within each treatment. *, **represent significant difference at α=0.05, α=0.01, respectively, using one-way ANOVA with Tukey-Kramer Honest Significant Difference (HSD) test. IL 1 beta Stimulation1% Enzyme Solution+IL 1 beta1% Wheat+IL 1 beta1% Breadfruit+IL1 beta0.00.51.01.5mRNA expression of IL8IL 1 beta Stimulation1% Enzyme Solution+IL 1 beta1% Wheat+IL 1 beta1% Breadfruit+IL1 beta0.00.51.01.52.0***mRNA expression of IL-6 119 Figure 5-7 a: IL-4 production under LPS plus IL-1β stimulation Figure 5-7 b: IL-10 production under LPS plus IL-1β stimulation LPS+IL1 beta Stimulation1%Enzyme Solution+LPS+IL1 beta1% Wheat+LPS+IL1 beta1% Breadfruit+LPS+IL1 beta0.00.20.40.60.81.0mRNA expression of IL4LPS+IL1 beta Stimulation1%Enzyme Solution+LPS+IL1 beta1% Wheat+LPS+IL1 beta1% Breadfruit+LPS+IL1 beta0.000.050.100.150.20mRNA expression of IL10 120 Figure 5-7 c: iNOS production under LPS plus IL-1β stimulation Figure 5-7 d: TNF-α production under LPS plus IL-1β stimulation LPS+IL1 beta Stimulation1%Enzyme Solution+LPS+IL1 beta1% Wheat+LPS+IL1 beta1% Breadfruit+LPS+IL1 beta0.000.050.100.15mRNA expression of iNOSLPS+IL1 beta stimulation1%Enzyme Solution+LPS+IL1 beta1% wheat+LPS+IL1 beta1% breadfruit+LPS+IL1 beta01234******mRNA expression of TNF alpha 121 Figure 5-7 e: IFN-γ production under LPS plus IL-1β stimulation Figure 5-7 f: MCP-1 production under LPS plus IL-1β stimulation LPS+IL1 beta Stimulation1%Enzyme Solution+LPS+IL1 beta1% Wheat+LPS+IL1 beta1% Breadfruit+LPS+IL1 beta0.00.51.01.5mRNA expression of IFN gammaLPS+IL1 beta Stimulation1%Enzyme Solution+LPS+IL1 beta1% Wheat+LPS+IL1 beta1% Breadfruit+LPS+IL1 beta0.00.10.20.3mRNA expression of MCP-1 122 Figure 5-7 g: IL-8 production under LPS plus IL-1β stimulation Figure 5-7 h: IL-6 production under LPS plus IL-1β stimulation Figure 5-7 Effect of digestive enzyme solution, wheat and breadfruit digestions on mRNA cytokine expression in Caco-2 cells stimulated with LPS (1000ng/mL) and IL-1β (100 ng/mL) for 24 hours. a) IL-4, b) IL 10, c) iNOS, d) TNF-α, e) IFN-γ, f) MCP-1, g) IL-8, h) IL- 6. Error bar represents the standard error of 3 replicates within each treatment. *, **, *** represent significant difference at α=0.05, α=0.01, α=0.001, using one-way ANOVA with HSD LPS+IL1 beta Stimulation1%Enzyme Solution+LPS+IL1 beta1% Wheat+LPS+IL1 beta1% Breadfruit+LPS+IL1 beta0.00.20.40.60.8mRNA expression of IL8LPS+IL1 beta Stimulation1%Enzyme Solution+LPS+IL1 beta1% Wheat+LPS+IL1 beta1% Breadfruit+LPS+IL1 beta02468* *mRNA expression of IL-6 123 5.4. Discussion 5.4.1. Cytotoxicity of wheat and breadfruit digestion to Caco-2 cells There are no previous studies of the cytotoxicity of breadfruit and few studies of wheat cytotoxicity that focused mainly on isolated and/or purified gliadin or gliadin-derived peptides, since they were identified as being important in wheat digestion issues, such as celiac disease (Ciclitira and Ellis, 1987; Lindfors et al., 2012). Wheat gliadin was found to trigger significant apoptosis in human cell lines including Caco-2 cells and this toxicity is considered to be responsible for the intestinal damage in celiac disease patients (Elli et al., 1987; Giovannini et al., 2000; 2003; Dolfini et al., 2002). Normal healthy epithelial cells have a life span of 3-5 days (Kim et al., 1998). The epithelial cells maintain their morphology by controlling programmed cell death or apoptosis. Acute apoptosis in epithelial layer results in the deletion of epithelial cells and loss of epithelial function (Kim et al., 1998). My study attempted to closely mimic intestinal epithelium response to wheat and breadfruit digestion by using non-isolated wheat and breadfruit flour digestions containing proteins but also starches, minerals and other nutrients. I found that 1% wheat or breadfruit digestion extracts did not significantly alter Caco-2 cell viability. However, as the concentration increases, digestion treatments reduced cell viability. Interestingly, breadfruit digestion treated cells also have a higher cell viability than wheat digestion treated cells, indicating that breadfruit might have a more positive impact on cell viability than wheat. 5.4.2. Cytokine response of breadfruit- and wheat-treated Caco-2 cells To fully understand the cytokine interaction of wheat and breadfruit digestion on Caco-2 cells, three stimulations were applied to Caco-2 cells in comparison to non- 124 stimulated cells. Caco-2 cells are hyposensitive to stimulation with LPS (Cario et al., 2000; Eckmann et al., 1993; Savidge et al., 2006) while IL-1β was shown to induce inflammatory responses in Caco-2 cells through nuclear factor-κB pathway in a process that can be reduced by LPS (Savidge et al., 2006; Suzuki et al., 2003). Together, these stimulants were used to model the responses of cells incubated with breadfruit and wheat digestion through the expression of cytokines (Jung et al., 1995; Savidge et al., 2006; Suzuki et al., 2003). The results from our study confirmed the earlier reports of hyposensitivity of Caco-2 cells to LPS, and IL-1β induced a significant increase in expression of pro-inflammatory cytokines. My study for the first time demonstrated the cytokine response of epithelial cells to breadfruit digestion in both immune stimulated conditions. In general, breadfruit digestion induced a very similar cytokine response on Caco-2 cells as wheat digestion with a few significant differences. The first significant finding was the induction of a higher expression of MCP-1 in non-stimulated cells by breadfruit digestion extracts (Fig 5-4 h). MCP-1 is a chemokine that regulates the migration and infiltration of monocytes, memory T lymphocytes, and natural killer cells (Deshmane et al., 2009). The second significant finding was the induction of iNOS when Caco-2 cells were challenged by LPS and breadfruit digestion extracts (Fig 5-5 h). iNOS can produce nitric oxide (NO), which acts as a cytotoxic agent in pathological processes and is usually expressed in response to immune-stimulatory cytokines, bacterial products, or infection in the intestine (Aktan, 2004). Previous studies described an early response to LPS in epithelium that included the upregulated expression and production of iNOS and NO 125 (Kim et al., 1998; Klampfer, 2011; Witthöft et al., 1998). The induced iNOS expression of breadfruit may be a result of productive immune defensive responses of the epithelial cells that would be beneficial in the context of infection; but, more research using infection models are required to draw the conclusion. Caco-2 cells stimulated with wheat digestion extract had a significantly higher IL-6 production. IL-6 can act as pro- and anti-inflammatory cytokine in the immune response depending on its pathway, either “classic-signaling “or “trans-signaling” (Scheller et al., 2011). Classic-signaling requires IL-6 to bind to the membrane-bound IL 6 receptor alpha (membrane-bound IL-6 receptor), while in trans-signaling, IL-6 will bind to a soluble IL-6 receptor (Rose-John et al., 2006). Both classic- and trans-signaling are associated with membrane-bound glycoprotein 130 (gp130) and activate intracellular signaling pathways including JAK/STAT (Janus kinase/signal transducer and activator of transcription), EPK/MAPK (extracellular signal-regulated kinases/mitogen-activated protein kinase), and PI3K/AKT (phosphoinositide 3-kinase/akt) (Waldner and Neurath, 2014). Classic-signalling of IL-6 shows anti-inflammatory activities including intestinal epithelial cell proliferation and inhibition of epithelial cell apoptosis (Scheller et al., 2011). In contrast, trans-signaling leads to pro-inflammatory activities, such as inhibition of T cell apoptosis and inhibition of Treg differentiation (Becker et al., 2004a; Scheller et al., 2011). Very few cells express membrane-bound IL-6 receptor including intestinal epithelial cells, neutrophils, monocytes/macrophages and some B and T cells, while soluble IL-6 receptor can be found and activated in a wide range of cell types (Becker et al., 2004b Scheller et al., 2011; Waldner and Neurath, 2014;). Recent studies found that IL-6/STAT 3 cascade 126 is implicated in proliferation and survival of tumor-initiating epithelial cells, both in vitro and in vivo (Lahm et al., 1992; Klampfer, 2011; Becker et al., 2004a; b; Grivennikov et al., 2009; Waldner and Neurath, 2014). These tumor-promoting effects are believed to be more relevant to trans-signalling since dysplastic epithelial cells exhibit greatly diminished surface expression of the membrane-bound IL-6 receptor (Becker et al., 2004a). However, during late colitis-associated cancer development, enhancing IL-6 trans-signaling or both classic- and trans-signaling can accelerate tumor growth (Grivennikov et al., 2009). Blocking of IL-6-dependent pathways has been developed in various therapeutics for gastrointestinal disease (Waldner and Neurath, 2014). The cause of the elevated IL-6 levels in response to wheat digestion extracts requires further study but this response was not seen with the breadfruit digestion extracts. 5.5. Summary My study showed that breadfruit digestion was not toxic to intestinal cells. Breadfruit digestion and wheat digestion induced similar cytokine responses in Caco-2 cells with some important differences. Breadfruit digestion induced a higher production of MCP-1 in unstimulated Caco-2 cells and a higher iNOS production in LPS stimulated cells. These data may provide an early indication of a possible protective immune response against bacterial infection that requires further study. The induction of IL-6 expression by wheat flour and not by breadfruit flour under IL 1β and/or LPS stimulation provides an early indication that breadfruit flour may be better tolerated and may also be a topic for future research. 127 Chapter 6. Effect of the Breadfruit Diet on Mice Health 6.1. Synopsis Model organisms are widely used to research human diseases, drug development and diet evaluation (Fields and Johnston, 2005; Hedges, 2002). Mice are one of the representative model organisms used by scientists because of the similarity in genome between mice and humans (over 90%) (Chinwalla et al., 2002; Hedges, 2002). The evaluation of animal health and biochemical analysis of animal tissues are considered as an indirect analysis of food consumed (O’Connell and Hedges, 1999). Although there has been a long history of breadfruit consumption by humans, the health impact of the breadfruit diet remains understudied. For example, the Mauritian population had a long-standing tradition of eating breadfruit; however, Mahomoodally and Ramalingum (2015) showed that the Mauritian population had very limited knowledge of breadfruit nutritional value and were not aware of breadfruit medicinal value at all. About 50% of the people in the survey did not even recognize breadfruit as a healthy food (Mahomoodally and Ramalingum, 2015). There are a limited amount of animal studies on breadfruit in the literature. These studies often had confusing experimental designs; therefore no definitive conclusions can be made (Aka et al., 2009; Adepeju et al., 2014; Grant, 1995). A properly conducted animal study of the breadfruit diet is significant not only in the exploration of breadfruit nutritional value but also as safety guidance for the breadfruit industry. 128 6.1.1. Objectives The objective of this study was to scientifically investigate and evaluate the impact of the breadfruit diet on CB57/6J mice performance as a case study. The first objective of the study was to evaluate the overall growth progress of the mice, including weight and hematological parameters, which are fundamental in food safety examination. The second objective of the study was to examine the intestinal health of the mice, by investigating ileum morphology, cytokine response and colon bacteria, as a continuous study of the in vitro cell model experiment. The outcome of these studies provides evidence to assess whether that the breadfruit diet has any adverse impact on mice overall growth or intestinal health. 6.2. Methods 6.2.1. Reagents Reagents used in this experiments included: DPPH (2,2-diphenyl-1-picrylhydrazyl; free radical; Sigma, USA), methanol (HPLC grade; Fisher Scientific, USA), trolox ((±)-6-hydroxy-2, 5, 7, 8-tetramethylchromane-2-carboxylic acid; 97%; Sigma), Rneasy® fibrous tissue mini kits (Qiagen, Germany), β-mercaptoethanol (>99%, Sigma), iScript cDNA synthesis kits (Bio-Rad Laboratories, Ontario, Canada), SsofastTM EvaGreen supermix (Bio-Rad Laboratories), nuclease- free water (Integrated DNA technologies, Coralville, USA), anhydrous ethyl alcohol (molecular grade; Commercial Alcohols, Ontario, Canada), QIAamp DNA stool mini kits (Qiagen), BCA (bicinchoninc acid) protein assay kits (Thermo Fisher Scientific, Manassas, USA), HEPES (fine white crystals, bioreagents; Fisher Scientific), 129 Tween 20 (PhytoTechnology Laboratories®, Shawnee Mission, USA), Hemoccult Sensa (Beckman Coulter, USA). 6.2.2. Diet design A breadfruit (BF) diet was formulated based on the standard 5LG4 diet (Purina, Gary Summit, MO, USA) by replacing all the ground wheat and wheat components (~45.5% of 5LG4) with breadfruit flour. Breadfruit flour was prepared from a single 6-year-old tree of the variety ‘Ma’afala’ as described previously (Chapter 4.2.2.) and provided to the Purina facility. Analysis of the two finished diets was conducted by a commercial lab to industry standard. The diets were isocaloric and nutritionally equivalent (Table 6-1). Table 6-1 Comparison of nutritional value between the breadfruit (BF) diet and 5LG4 diet Title Unit 5LG4 diet BF diet Calories USA Cal/100g 363 357 Calories Canada Cal/100g 328 330 Total fat as triglycerides by GC g/100g 6.53 5.93 Saturated fatty acid g/100g 1.41 1.42 cis-Monounsaturated fatty acid g/100g 1.49 1.45 cis-Polyunsaturated fatty acid g/100g 3.26 2.71 Omega-6 fatty acids g/100g 2.85 2.3 Omega-3 fatty acids g/100g 0.41 0.41 Trans fatty acids g/100g 0.03 0.05 Conjugated linoleic acid g/100g <0.01 <0.01 130 Title Unit 5LG4 diet BF diet Cholesterol mg/100g 28.6 23.6 Sodium mg/100g 291 223 Carbohydrates g/100g 56.7 60.1 Total dietary fibre g/100g 17.6 13.4 Total sugars g/100g 1.9 4.3 Fructose g/100g 0.24 1 Glucose g/100g <0.2 0.79 Sucrose g/100g 1.6 2.5 Maltose g/100g <0.5 <0.5 Lactose g/100g <0.5 <0.5 Protein g/100g 19.39 15.8 Protein factor 6.25 6.25 Total vitamin A RE/100g 71 <20 Retinol IU/100g 169 <50 Beta carotene IU/100g 200 <50 Calcium mg/100g 1190 1260 Iron mg/100g 39.4 40.4 Ash g/100g 6.94 7.18 Moisture g/100g 10.43 10.95 Vitamin C mg/g <1.0 <1.0 Vanadium ppm (w/w) 1.8 2.65 131 Title Unit 5LG4 diet BF diet Zinc ppm (w/w) 65.7 54 Zirconium ppm (w/w) 0.5 0.8 Iodine ppm (w/w) 2.13 1.56 Niacin mg/100g 11.5 6.9 Vitamin B1.HCl mg/100g 3.2 1.6 Vitamin B12 mcg/100g 5.5 Vitamin B2 mg/100g 0.91 0.78 Vitamin B6 mg/100g 0.79 0.67 Vitamin E IU/100g 3 3.3 mg/100g 2 2.2 Biotin ppm (w/w) 35.6 32.8 Boron ppm (w/w) 2.6 5.9 Aluminum ppm (w/w) 147 203 Antimony ppm (w/w) 0.02 0.04 Arsenic ppm (w/w) 0.7 0.68 Barium ppm (w/w) 7.71 6.4 Beryllium ppm (w/w) 0.04 0.07 Bismuth ppm (w/w) <0.02 <0.02 Cadmium ppm (w/w) 0.076 0.098 Calcium ppm (w/w) 13400 17200 Chromium ppm (w/w) 1.54 2.23 132 Title Unit 5LG4 diet BF diet Cobalt ppm (w/w) 0.56 0.66 Copper ppm (w/w) 7.49 7.88 Iron ppm (w/w) 345 486 Lead ppm (w/w) 0.11 0.24 Lithium ppm (w/w) 0.2 0.3 Magnesium ppm (w/w) 2190 1650 Manganese ppm (w/w) 120 143 Mercury ppm (w/w) 0.005 0.007 Molybdenum ppm (w/w) 1.57 0.94 Nickel ppm (w/w) 1.01 1.41 Phosphorus ppm (w/w) 9390 10400 Potassium ppm (w/w) 7160 11000 Selenium ppm (w/w) 0.4 0.5 Silver ppm (w/w) <0.02 <0.02 Sodium ppm (w/w) 2810 2060 Strontium ppm (w/w) 12.9 16.8 Thallium ppm (w/w) <0.01 0.01 Thorium ppm (w/w) 0.2 0.2 Tin ppm (w/w) 0.02 0.02 Titanium ppm (w/w) 19.2 24.6 Uranium ppm (w/w) 0.37 0.67 133 Non-nutrient chemistry of the diets To determine whether the breadfruit flour included any non-nutrient phytochemicals that may have impacted the animal health, the antioxidant content of the diets was determined by standardized DPPH protocols (Turi and Murch, 2013). Briefly, 3 g of the ground diets (3 replicates each) was mixed with 10 mL of methanol (0.3 g/ml), centrifuged and syringe filtered (0.22 µm MCE filter, sterile; Fisher Scientific). A serial dilution of the sample (0.165 g/mL, 0.091 g/mL, 0.050 g/mL, 0.027 g/mL, 0.015 g/mL, 0.0083 g/mL, and 0.0046 g/mL) and trolox standard solutions (1 µM, 8 µM, 16 µM, 24 µM, 32, µM, 40 µM, and 50 µM) were prepared for analysis. 100 µL diet samples or trolox standard solutions were pipetted (duplicate) into Costar 96-well EIA/RIA clear flat bottom plates (Bio-Rad Laboratories, Ontario) with 100 µL of the DPPH solution (0.1 mM in methanol). The absorbance was read by a Synergy HT Multi-Mode Microplate Reader (BioTek Instruments, Vermont) using Gen5: Microplate Data Collection and Analysis Software (BioTek). Data was collected each minute for a total of 20 minutes at 562 nm. Blank samples with either methanol and/or DPPH was analyzed to access the contribution of reagents. The BF diet and 5LG4 diet were not significantly different in their scavenging activity at 15 minutes, indicating that significant quantities of reactive phytochemicals were not present (Figure 6-1). 134 Figure 6-1 Comparison of scavenging activity percentage at 15 minutes between breadfruit diet and 5LG4 diet using DPPH methods. Bars represents standard error calculated from the three replicates 6.2.3. Experimental animals The animal experiments were performed by the staff at Jackson Laboratories, California, USA according to standard operating protocols. The animal protocol was approved by the University of California San Diego Institutional Animal Care and Use Committee (IACUC) to ensure the highest quality animal use and care. Mice (C57BL/6, Jackson Labs) were 7 week old mice at the beginning of the experiment and were housed for 3 weeks in positively ventilated polycarbonate cages with HEPA filtered air at a density of 4 mice per cage. For identification, the mice were ear-notched. The light source was provided by using artificial fluorescent lighting, creating a 12 h light/dark cycle. The room temperature was controlled at 22±4°C with 50±15% humidity. A total of 32 mice were randomly assigned into 2 groups. Each 5LG4 diet: y = 27.654ln(x) + 79.667R² = 0.958Breadfruit diet: y = 28.092ln(x) + 79.902R² = 0.95401020304050607080901000.000 0.005 0.010 0.015 0.020Scavenging activity percentage (AA%) at 15 minDiet weight (g)Breadfruit diet 5LG4 dietLog. (Breadfruit diet ) Log. (5LG4 diet) 135 group had an equal number of female (8) and male (8) mice. One group received the 5LG4 diet and the other group received the breadfruit diet (BF diet). Problems with the breadfruit diet crumbling in the cages meant that it was not possible to accurately determine food intake or absolute amount of food consumed. 6.2.4. Overall growth evaluation and hematology analysis Body weight, and food and water intake were measured daily at the same time. Clinical observations were made daily, examining the general health condition and any skin lesions. At the terminal point, the mice were sacrificed by CO2 asphyxiation at the end of the third week. The terminal blood was collected by cardiocentesis and the whole blood was submitted for clinical chemistry analysis in Comparative Pathology Laboratory (CPL) (Davis, CA, USA). The whole body composition measurements of fat, lean, free water, and total water mass was conducted using EchoMRI-100 Analyzer (EchoMRITM, USA) in the Jackson Laboratory. 6.2.5. Tissue collection The organs were weighed individually and sent as snap-frozen tissue to the UBC Okanagan. Feces were collected on days 3, 7, 14, and 21 from each cage, frozen in liquid nitrogen and then sent to the UBC Okanagan campus. One-third of the ileum sections of the mice were stored in RNAlater®, an RNA stabilization reagent (Qiagen®), and shipped frozen to the UBC Okanagan campus. A 3- to 5-mm section of the ileum was fixed in 10% buffered neutral formalin with paraffin, 136 sectioned following standard histological methods and then stained by Hematoxylin and Eosin (H&E) method. The frozen tissues, feces and RNA later ileum section were stored in -80° before analysis. 6.2.6. Feces protein, total mineral analysis, and fecal occult blood detection Feces from the same cage and the same day were homogenized and mixed using a CoorsTM porcelain mortar and pestle (Sigma, USA). The protein content was extracted from the feces using a protein extraction buffer as described in Chapter 4.2.4. In summary, 10 mg of the feces were homogenized with 1 mL of protein extraction buffer (20 mM HEPES, 150 mM NaCl) and sonicated for 20 minutes. The protein extracts were diluted 1:1 in the protein extraction buffer before BCA analysis. The BCA analysis was conducted following the standard protocol as described in Chapter 4.2.4. The mineral content of the feces was calculated by the difference of weight of the feces before and after incineration at 600°C for 2 h in an Isotemp programmable muffle furnace (Fisher Scientific, Ottawa, ON), according to AACC 08-03.The fecal occult blood was detected using a Hemoccult Sensa® kit (Beckman Coulter, USA) following the manufacturer’s protocol. 6.2.7. Ileum morphology examination The morphological analysis of the H&E stained ileum slides was conducted, following the method published by Generoso et al. (2015). Villi pictures (10 pictures × 4 mice) were taken from each group using a camera (QImaging, Surrey, BC, Canada) attached to a microscope (Olympus America Inc., PA, USA) and each 137 parameter was measured blindly using ImageJ 1.47v software (Wayne Rasband, National Institutes of Health, Maryland, USA). The following parameters were measured: distance between villi; villus height and thickness; the crypt depth; the thickness of lamina propria and epithelium: the length of mucosa, submucosa, and muscularis externa; and the number of goblet cells and red blood cells. 6.2.8. Major cytokine response on ileum RNA extraction was performed on ileum tissue of the mice, using a RNeasy® fibrous tissue mini kit, following the manufacturer’s instructions. Briefly, the ileum tissue was lysed in Buffer RLT with β-mercaptoethanol using the Mixer Mill MM 400 (Retsch®, Germany). The sample was incubated with proteinase K at 55°C to remove protein content. Debris content was removed by centrifugation, and the supernatant was mixed with ethanol and filtered through an RNeasy mini column. The RNA of the sample bound to the silica membrane of the column and the impurities and DNA in the sample were washed away by the DNase solution and Buffer RDD, Buffer RW1, and Buffer RPE. Finally, the RNA was collected in RNase-free water and the concentration of the RNA was determined by the NanoDrop 2000c UV-Vis Spectrophotometer (Thermo Fisher Scientific, Manassas, USA). Based on the RNA concentration, complementary DNA (cDNA) copies were synthesized using an iScript cDNA synthesis kit by following the manufacturer’s instructions (as described in Chapter 4.2.7.). cDNA samples were diluted 10 times in RNase-free water. The real-time polymerase chain reaction (RT-qPCR) analysis was conducted 138 on the cDNA samples using a SsofastTM EvaGreen Supermix, following the manufacturer’s instructions (as described in Chapter 4.2.7.). The production of TNF-α, IFN-γ, IL-10, IL-6, and iNOS was examined, using 18S rRNA as a reference gene. The design and testing of the primers used in the study were conducted by Ghosh et al. (2015). 6.2.9. Quantification of bacterial groups in the colon DNA was extracted from the frozen colon tissue of the mice using a QIAamp DNA stool mini kit following the manufacturer’s protocol. In summary, one fifth of the frozen colon tissue was collected and homogenized in Buffer ASL. The protein in the sample was digested by proteinase K in a 70°C water bath. The DNA was bound to the QIAamp membrane and the impurities were washed away by Buffer AW1, AW2, and PRE. Eventually, the DNA was collected in Buffer AE. The concentration of the DNA was determined by the NanoDrop 2000c UV-Vis Spectrophotometer. The production of Firmicutes members, Bacteroidetes members, Enterobacteriacae family, Lactobacillus spp., and Bifidobacterium spp. in the colon was quantified by RT-qPCR, using Eubacteria production as a reference in the analysis. The sequence specificity of the primers was verified by Baker et al. in 2012. The qPCR analysis was conducted in the same manner as described in Chapter 4.2.7. 6.2.10. Statistical analysis All statistical analysis were conducted using JMP® 10.0.0 (SAS Institute, Cary, NC) and GraphPad Prism 5.0 software (GraphPad Software Inc., La Jolla, CA). A 139 series of independent two sample t-tests or two-way ANOVA analyses were conducted to determine if there were significant differences between treatments with a type 1 error rate of 0.05. Graphs were created using GraphPad Prism 5.0 software and Microsoft Excel 2013 (Microsoft Corporation, Santa Rosa, CA). 6.3. Results 6.3.1. Overall health and growth During the three-week trial, there was no report of death or any abnormal clinical symptoms for both male and female BF-fed (breadfruit-fed) mice. Both BF- and 5LG4-fed mice showed similar growth patterns (Figure 6-2a). Three weeks of the breadfruit diet resulted in a slightly higher growth rate (7.32% overall, 5.82% male, 8.82% female) in mice than the 5LG4 diet (Figure 6-2b), with an equal effect on both male and female mice (two-way ANOVA, Diet effect: p<0.0001<α=0.05, Gender effect: p=0.3020> α =0.05, Interaction Effect: p=0.1232> α =0.05). Since the breadfruit diet was very crumbly, the food loss during the trial was significant, and more breadfruit diet was used in the feeding, therefore the usage cannot be interpreted as the food intake (Figure 6-3). There was a significant higher daily water consumption (12.7% overall, 14.4% male, 10.6% female) in mice fed on the breadfruit diet compared to mice fed on the 5LG4 diet (Figure 6-4a & b), but there was no interaction between diet and gender (two-way ANOVA, Diet effect: p<0.0001< α =0.0001, Gender effect: p=0.0011< α =0.05, Interaction effect: p=0.2059> α =0.05). 140 Figure 6-2 a Figure 6-2 b Figure 6-2 Comparison of daily body weight (a) and growth rate (b) of mice fed on breadfruit (BF) and 5LG4 diets. Bars represents the standard error of the measurement among eight mice from the same group. * represents significant difference at α=0.05, ** represents significant difference at α=0.01, *** represents significant difference at α=0.001 0510152025300 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21Body weight (g)Days5LG4-fed mice Female 5LG4-fed miceMale 5LG4-fed mice BF-fed miceMale BF-fed mice Female BF-fed mice0%2%4%6%8%10%12%14%5LG4 diet BF diet 5LG4 diet BF diet 5LG4 diet BF dietMice Male mice Female miceGrowth rate*** ***** 141 Figure 6-3 Comparison of food usage of mice fed on the breadfruit (BF) and 5LG4 diets Figure 6-4 a 05101520250 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Food consumption (g)Experimental DaysFemale 5LG4-fed mice Male 5LG4-fed miceMale BF-fed mice Female BF-fed mice01234560 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21Water consumption (mL)Experimental Days 5LG4-fed mice Female 5LG4-fed miceMale 5LG4-fed mice BF-fed mice 142 Figure 6-4 b Figure 6-4 Comparison of daily water consumption (a) and average daily water consumption (b) of mice fed on breadfruit (BF) and 5LG4 diets. Bars represents the standard error of the measurement among eight mice from the same group. * represents significant difference at α=0.05, ** represents significant difference at α=0.01, *** represents significant difference at α=0.001 At the end of the three-week trial, the body composition was similar between BF and 5LG4 diet-fed mice (Table 6-2). Male mice consuming the BF diet had significantly higher body weight (4% higher) and lower fat (2.2 % less) than male mice consuming the 5LG4 diet. There were few significant differences in the weights of various tissues and organs in response to the diet. Female BF-fed mice had significantly larger duodena and male BF-fed mice had significantly heavier femurs, while all the other organs, including the brain, heart, liver, and kidney, were not significantly different in weight. 0.00.51.01.52.02.53.03.54.04.55LG4 diet BF diet 5LG4 diet BF diet 5LG4 diet BF dietMice Male mice Female miceDaily water intake (ml/animal/day)*** *** ** 143 Table 6-2 Comparison of average body composition and tissue weight between the BF-fed (breadfruit-fed) mice and 5LG4-fed mice Sex 5LG4 diet BF diet Male mice Female mice Diet 5LG4 diet BF diet 5LG4 Diet BF Diet Name Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE Body weight (g) 21.0 0.7 22.2 0.7 23.7a 0.4 24.7b 0.3 18.4 0.3 19.7 0.6 Fat 17.1% 0.7% 15.7% 1.0% 15.0%a 0.5% 12.8%b 0.6% 19.1% 0.7% 18.5% 1.2% Lean 73.4% 0.9% 72.9% 0.9% 75.4% 1.1% 74.7% 0.7% 71.5% 0.9% 71.1% 1.5% Free water 0.5% 0.1% 0.5% 0.1% 0.5% 0.1% 0.4% 0.0% 0.4% 0.1% 0.6% 0.1% Total water 60.7% 0.7% 60.4% 0.8% 62.3% 0.9% 62.0% 0.5% 59.0% 0.8% 58.9% 1.3% Brain (g) 0.45 0.004 0.44 0.007 0.46 0.003 0.45 0.006 0.44 0.006 0.43 0.013 Heart (g) 0.12 0.003 0.12 0.005 0.13 0.004 0.13 0.006 0.11 0.004 0.11 0.005 Kidney (g) 0.25 0.009 0.26 0.008 0.28 0.009 0.29 0.006 0.22 0.008 0.24 0.008 Bladder (g) 0.02 0.002 0.02 0.002 0.02 0.001 0.03 0.003 0.02 0.003 0.01 0.002 144 Sex 5LG4 diet BF diet Male mice Female mice Diet 5LG4 diet BF diet 5LG4 Diet BF Diet Name Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE Lungs (g) 0.23 0.010 0.22 0.010 0.24 0.011 0.22 0.010 0.21 0.014 0.21 0.018 Thymus (g) 0.03 0.004 0.03 0.005 0.03 0.006 0.03 0.007 0.03 0.006 0.04 0.005 Spleen (g) 0.06 0.002 0.06 0.003 0.06 0.002 0.07 0.003 0.06 0.004 0.06 0.005 Lymph node (g) 0.01 0.003 0.01 0.002 0.02 0.005 0.01 0.003 0.01 0.004 0.01 0.002 Salivary gland (g) 0.12 0.011 0.12 0.013 0.14 0.017 0.14 0.016 0.11 0.015 0.10 0.019 Liver (g) 0.94 0.052 0.88 0.066 1.12 0.033 0.93 0.126 0.76 0.033 0.83 0.047 Pancreas (g) 0.11 0.007 0.11 0.006 0.12 0.011 0.13 0.006 0.10 0.010 0.10 0.008 Duodenum (g) 0.28 0.024 0.22 0.021 0.28 0.037 0.22 0.025 0.20a 0.027 0.31b 0.028 Jejunum (g) 0.25 0.042 0.21 0.012 0.23 0.024 0.22 0.018 0.27 0.084 0.19 0.013 Ileum (g) 0.20 0.037 0.18 0.008 0.22 0.071 0.19 0.011 0.18 0.028 0.17 0.010 Colon (g) 0.15 0.009 0.16 0.012 0.16 0.012 0.16 0.018 0.13 0.013 0.15 0.017 145 Sex 5LG4 diet BF diet Male mice Female mice Diet 5LG4 diet BF diet 5LG4 Diet BF Diet Name Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE Testes (g) 0.18 0.024 0.18 0.024 0.18 0.004 0.18 0.005 / / / / Epididymis (g) 0.05 0.007 0.05 0.007 0.05 0.007 0.05 0.005 / / / / Uterus (g) 0.09 0.014 0.08 0.011 / / / / 0.09 0.016 0.08 0.010 Mammary gland (g) 0.22 0.012 0.20 0.015 0.22 0.015 0.18 0.016 0.23 0.021 0.23 0.023 Pituitary gland (g) 0.002 0.001 0.002 0.000 0.002 0.001 0.002 0.001 0.002 0.001 0.001 0.000 Adrenal gland (g) 0.01 0.001 0.01 0.001 0.01 0.001 0.01 0.001 0.01 0.001 0.01 0.000 Ears (g) 0.04 0.005 0.04 0.004 0.06 0.006 0.04 0.007 0.03 0.004 0.04 0.005 Tail tip (g) 0.06 0.006 0.13 0.047 0.06 0.007 0.12 0.058 0.06 0.010 0.13 0.078 Skin (g) 0.009 0.003 0.007 0.001 0.013 0.006 0.008 0.001 0.005 0.000 0.006 0.001 Femur (g) 0.06 0.003 0.09 0.009 0.07a 0.005 0.08b 0.002 0.06 0.003 0.09 0.019 Numbers followed by different letter in each section are significant difference at alpha=0.05, using 2 sample t test 146 6.3.2. Hematology analysis BF-fed mice established a slightly different white blood cell profile, but very similar red blood cell and platelets (thrombocytes) profiles as the 5LG4-fed mice (Table 6-3). For the total white blood cells as well as the two major components of white blood cells, neutrophils and lymphocytes, gender played a role in the mice’s responses to the BF diet (two-way ANOVA, Interaction effect between gender and diet for white blood cell: p=0.0006<α=0.05, for neutrophils: p=0.0077<α=0.05, and for lymphocytes: p=0.0002<α=0.05). Female BF-fed mice had significantly lower white blood cell, neutrophil, and lymphocyte count than female 5LG4-fed mice while male BF-fed mice had significant higher lymphocyte than male 5LG4-fed mice. No significant difference was found in the monocyte cell number between the two diets in both genders. For eosinophil and basophil counts, there was no significant difference between the two diets in the female mice, but male BF-fed mice had significantly lower eosinophil and basophil count than male 5LG4-fed mice. When the cell counts were converted into the percentage content in white blood cells, the differences between the two diet groups became smaller. Male 5LG4-fed mice had significantly lower lymphocyte and eosinophil percentage than male BF-fed mice, while female 5LG4-fed mice had significantly higher neutrophil percentage than female BF-fed mice. Differences found in the red blood cell and platelet profiles were not statistically significant with the exception of female BF-fed mice that had a significantly higher MCV (mean corpuscular volume) content than female 5LG4 fed mice. 147 Table 6-3 Comparison of blood hematology between mice fed on the breadfruit (BF) diet and 5LG4 diet Sex 5LG4 diet BF diet Male mice Female mice Diet 5LG4 diet BF diet 5LG4 Diet BF diet Title Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE White blood cell (K/µl) 7.1 0.7 5.7 0.5 5.6 0.3 7.0 0.7 8.5a 1.1 4.4b 0.5 Absolute neutrophil cells (K/µl) 1.7a 0.2 1.2b 0.1 1.5 0.1 1.6 0.2 1.9a 0.3 0.8b 0.1 Absolute lymphocyte cells (K/µl) 4.9 0.5 4.2 0.4 3.7a 0.3 5.2b 0.5 6.1a 0.8 3.2b 0.4 Absolute monocyte cells (K/µl) 0.23 0.03 0.21 0.02 0.19 0.03 0.19 0.03 0.28 0.05 0.23 0.03 Absolute eosinophil cells (K/µl) 0.19 0.03 0.12 0.02 0.16a 0.02 0.09b 0.02 0.22 0.06 0.15 0.03 Absolute basophil cells (K/µl) 0.06a 0.01 0.03b 0.01 0.06a 0.01 0.03b 0.01 0.06 0.02 0.04 0.01 Neutrophil % 24.5a 1.4 19.7b 1.2 27.4 2.0 21.8 2.0 21.5a 1.2 17.7b 0.8 Lymphocyte % 68.6a 1.8 73.6b 1.2 65.1a 2.7 74.1b 2.1 72.1 1.8 73.1 1.3 Monocyte % 3.3 0.3 3.9 0.4 3.4 0.5 2.6 0.2 3.2 0.5 5.2 0.3 Eosinophil % 2.7 0.3 2.2 0.4 3.0a 0.4 1.2b 0.3 2.5 0.6 3.2 0.5 Basophil % 0.9 0.1 0.6 0.1 1.1 0.2 0.4 0.1 0.7 0.2 0.8 0.1 148 Sex 5LG4 diet BF diet Male mice Female mice Diet 5LG4 diet BF diet 5LG4 Diet BF diet Title Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE Red blood cell (M/µl) 10.7a 0.1 10.1b 0.2 10.8 0.2 10.0 0.4 10.7 0.1 10.3 0.2 Hemoglobin (g/dL) 14.2a 0.2 13.5b 0.3 14.4 0.3 13.4 0.5 14.1 0.3 13.6 0.1 Hematocrit % 43.3 0.6 41.1 0.9 44.4 0.9 40.9 1.7 42.1 0.7 41.3 0.7 MCV (fL) 40.3 0.2 40.6 0.2 41.1 0.2 40.9 0.1 39.5a 0.2 40.2b 0.2 MCH (pg) 13.3 0.1 13.3 0.1 13.3 0.1 13.4 0.1 13.2 0.1 13.3 0.1 MCHC (g/dL) 32.9 0.2 32.9 0.1 32.5 0.3 32.8 0.2 33.4 0.3 33.0 0.2 RDW % 17.9 0.1 17.6 0.1 17.7 0.1 17.3 0.1 18.1 0.2 17.9 0.2 Platelets (K/µL) 1260 53 1087 81 1327 84 1105 118 1193 61 1069 120 MPV (fL) 5.5 0.0 5.7 0.1 5.6 0.0 5.6 0.1 5.5 0.1 5.7 0.1 Numbers followed by different letter in each section are significant difference at alpha=0.05, using 2 sample t test. MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin), MCHC (mean corpuscular hemoglobin concentration), RDW (red cell distribution width), MPV (mean platelet volume) 149 6.3.3. Fecal protein, total mineral analysis, and fecal blood detection Feces collected from the BF-fed mice tended to have a higher (1-7%) protein content than the 5LG4-fed mice (Figure 6-5). Both male and female BF-fed mice showed a significantly higher fecal protein than 5LG4-fed mice at Day 7 (Figure 6-5b). However, in terms of total mineral content, the breadfruit diet fed mice showed a trend of lower percentage (1-6%) than the 5LG4 diet fed mice (Figure 6-6), especially at Day 7 and 14, where both male and female BF-fed mice had significantly lower fecal mineral content than 5LG4 fed mice (Figure 6-6 b & c). By the end of the three-week trial (Day 21), there was no significant difference in the fecal protein or mineral content between the two diet groups (Figure 6-5d & Figure 6-6d). In spite of the collection date, gender, and diet, the fecal blood detection showed that there was no blood in all of the feces collected. Figure 6-5 a 0%4%8%12%16%20%5LG4 Diet BF Diet 5LG4 Diet BF Diet 5LG4 Diet BF DietMice Male mice Female miceFecal protein content at Day 3 150 Figure 6-5 b Figure 6-5 c 0%5%10%15%20%25%5LG4 Diet BF Diet 5LG4 Diet BF Diet 5LG4 Diet BF DietMice Male mice Female miceFecal protein content at Day 7 *** ***0%5%10%15%20%25%5LG4 Diet BF Diet 5LG4 Diet BF Diet 5LG4 Diet BF DietMice Male mice Female miceFecal protein content at Day 14 * * 151 Figure 6-5 d Figure 6-5 Comparison of fecal protein content from mice fed with the breadfruit (BF) and 5LG4 diets at Day 4 (a), Day 7 (b), Day 14 (c), and Day 21 (d). *, **, *** represents a significant difference between the two groups using 2 sample t-test at alpha level 0.05, 0.01, 0.001, respectively. Bars represents the standard error of the measurement among eight mice from the same group Figure 6-6 a 0%4%8%12%16%20%5LG4 Diet BF Diet 5LG4 Diet BF Diet 5LG4 Diet BF DietMice Male mice Female miceFecal protein content at Day 210%2%4%6%8%10%12%14%16%5LG4 Diet BF Diet 5LG4 Diet BF Diet 5LG4 Diet BF DietMice Male mice Female miceFecal total minerial content at Day 3** *** 152 Figure 6-6 b Figure 6-6 c 0%2%4%6%8%10%12%14%16%5LG4 Diet BF Diet 5LG4 Diet BF Diet 5LG4 Diet BF DietMice Male mice Female miceFecal total mineral content at Day 7*** ** **0%2%4%6%8%10%12%14%16%5LG4 Diet BF Diet 5LG4 Diet BF Diet 5LG4 Diet BF DietMice Male mice Female miceFecal total mineral content at Day 14 ****** 153 Figure 6-6 d Figure 6-6 Comparison of total mineral content from mice fed with the breadfruit (BF) and 5LG4 diets at Day 4 (a), Day 7 (b), Day 14 (c), and Day 21 (d). *, **, *** represents a significant difference between the two group using 2 sample t-test at alpha level 0.05, 0.01, 0.001, respectively. Bars represents the standard error of the measurement among eight mice from the same group 6.3.4. Ileum morphology examination Mice from both diet groups had no significant difference in the villus height and thickness; distance between the villi; crypt depth; thickness of lamina propria and epithelium; length of mucosa, submucosa, and muscularis externa; and number of goblet cells and red blood cells (Table 6-4). There was no difference in the ileum morphology between 5LG4-fed and BF-fed mice (Figure 6-7).0%2%4%6%8%10%12%14%16%18%5LG4 Diet BF Diet 5LG4 Diet BF Diet 5LG4 Diet BF DietMice Male mice Female miceFecal total mineral content at Day 21 154 Table 6-4: Histological examination of ileum morphology Sex 5LG4 diet BF diet Male mice Female mice Diet 5LG4 diet BF diet 5LG4 diet BF diet Title Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE Distance between villi (µm) 6.43 0.95 6.28 0.72 6.26 0.94 5.92 0.49 6.60 1.50 6.63 1.23 Height of villus (µm) 110.2 9.23 117.3 6.66 120.4 10.41 125.5 6.46 99.98 11.74 109.0 8.90 Thickness of villus (µm) 51.04 2.83 52.41 2.50 53.36 1.49 55.59 3.51 48.73 4.81 49.23 2.14 Crypt depth (µm) 68.75 5.00 56.66 2.31 70.38 7.93 61.92 2.07 67.12 4.85 51.40 0.78 Thickness of lamina propria (µm) 20.71 1.98 18.01 1.93 21.07 1.30 19.05 2.91 20.36 3.46 16.97 2.00 Epithelium thickness (µm) 15.48 1.09 17.26 0.60 16.45 1.63 18.40 0.52 14.50 1.02 16.13 0.60 155 Sex 5LG4 diet BF diet Male mice Female mice Diet 5LG4 diet BF diet 5LG4 diet BF diet Title Mean SE Mean SE Mean SE Mean SE Mean SE Mean SE Length of mucosa (µm) 171.3 13.05 170.2 8.00 183.3 16.03 182.8 7.33 159.3 16.33 157.7 9.57 Length of submucosa (µm) 9.90 0.68 9.26 0.52 8.86 0.41 9.44 0.60 10.95 0.95 9.08 0.76 Length of muscularis externa (µm) 21.24 2.07 21.25 1.50 22.08 3.40 23.50 2.28 20.39 1.77 19.01 0.40 Number of goblet cells 6 0 6 0 7 0 7 0 5 0 6 0 Number of red blood cells 5 2 5 2 5 1 3 2 6 3 7 2 156 Figure 6-7 a: 5LG4-fed male mice Figure 6-7 b: BF-fed male mice 157 Figure 6-7 c: 5LG4-fed female mice Figure 6-7 d: BF-fed female mice Figure 6-7 Representative histopathology of the ileum of 5LG4-fed male mice (a), BF-fed male mice (b), 5LG4-fed female mice (c), and BF-fed female mice (d) at 3 weeks of age stained with haematoxylin and eosin (H&E).Scale bar is 50 µm. 158 6.3.5. Major cytokine response on ileum Cytokines, including TNF-α, IL-10, IL 6, and IFN-γ, were examined in the ileum tissue of the mice and no significant difference was found as a result of consumption of the 5LG4 or breadfruit diet (Figure 6-8 a-d). Female BF-fed mice had significantly higher iNOS production than female 5LG4-fed mice (Figure 6-8e); however, the difference was less than 0.5 fold. BF-fed mice had very similar cytokine responses to 5LG4-fed mice in their ileums. Figure 6-8 a: TNF-α production Male mice ileum Female mice ileum024685LG4 Diet BF DietmRNA expression of TNF alpha 159 Figure 6-8 b: IFN-γ production Figure 6-8 c: IL-10 production Male mice ileum Female mice ileum02468105LG4 Diet BF DietmRNA expression of IFN gammaMale mice ileum Female mice ileum02468105LG4 Diet BF DietmRNA expression of IL-10 160 Figure 6-8 d: IL-6 production Figure 6-8 e: iNOS production Figure 6-8 Comparison of cytokine expression between ileums of breadfruit (BF)-and 5LG4-fed mice, a) TNF-α, b) IFN-γ, c) IL-10, d) IL-6, e) iNOS. * represents a significant difference between the two groups using 2 sample t-test at alpha level 0.05. Middle line denotes media, whiskers are determined by Tukey method, which represent largest value below 75th percentile plus 1.5 times interquartile distance IQR or lowest value above 25th percentile minus 1.5 times IQR. Male mice ileum Female mice ileum02468105LG4 Diet BF DietmRNA expression of IL-6Male mice ileum Female mice ileum024685LG4 Diet BF Diet*mRNA expression of iNOS 161 6.3.6. Quantification of bacterial groups in the colon Gene expression of bacterial groups, Bifidobacterium spp., Lactobacillus spp., and Enterobacteriacae in the colon were compared and no significant differences were found between 5LG4-fed and BF-fed mice (Figure 6-9 a & b). Both male and female mice fed on the breadfruit diet showed a higher gene expression of Bacteroidetes than mice fed on the 5LG4 diet. Female BF-fed mice showed a higher gene expression of Firmicutes. However, the ratio between Firmicutes and Bacteroidetes was not significantly different between the two diets (male 5LG4-fed mice: 0.61±0.17, male BF-fed mice: 0.20±0.05, female 5LG4-fed mice: 0.45±0.12, female BF-fed mice: 0.30±0.13) (Figure 6-9). Figure 6-9 a: Bacteroidetes Bacteroidetes expressionMale mice Female mice0204060805LG4 Diet BF diet** 162 Figure 6-9 b: Firmicutes Figure 6-9 c: Bifidobacterium spp. Firmicutes expressionMale mice Female mice02468105LG4 Diet BF diet***Bifidobacteriumspp. expressionMale mice Female mice0102030405LG4 Diet BF diet 163 Figure 6-9 d: Lactobacillus spp. Figure 6-9 e: Enterobacteriacae Figure 6-9 Comparison of bacteria expression between ileums of breadfruit diet and 5LG4 diet fed mice, a) Bacterioidetes, b) Firmicutes, c) Bifidobacterium spp., d) Lactobacillus spp., e) Enterobacteriacae. *, **, *** represents significant difference between the two groups using 2 sample t-test at alpha level 0.05, 0.01, 0.001, respectively. Middle line denotes media, whiskers are determined by Tukey method, which represent largest value below 75th percentile plus 1.5 times interquartile distance (IQR) or lowest value above 25th percentile minus 1.5 times IQR. Lactobacillus spp. expressionMale mice Female mice0204060805LG4 Diet BF dietEnterobacteriaceae expressionMale mice Female mice01002003004005LG4 Diet BF diet 164 6.4. Discussion 6.4.1. Overall heath and growth Of the few animal studies, especially rodent studies, found related to breadfruit, definitive conclusions are not possible (Adepeju et al., 2014; Grant, 1995; Aka et al., 2009). Grant (1995) reported the death of 4 male Hooded Lister rats after consumption of breadfruit seed extracts. The small sample size in the experimental design makes the data difficult to interpret, the preparation of the diet is unclear and it is possible that the species was misidentified. The paper identified the seeds as representing the species A. altilis (breadfruit) seeds obtained from a tree at the Mayaguez Institute of Tropical Agriculture (MITA, Puerto Rico). However, the GRIN (Germplasm Resources Information Network) database provided by the U.S. Department of Agriculture, shows that the only A. altilis cultivar that might possibly produce seeds was not received until 2005. In the 1990s, Puerto Rico had only seedless A. altilis, derived from the British and French introductions in late 18th century. Therefore, the plant material used in this paper is suspect. Aka et al. (2009) described the impact of the breadfruit diet on male albino rats. They reported that a raw and partially raw breadfruit diet induced severe weight loss in male rats, but cooked breadfruit resulted in weight gain (Aka et al., 2009). However, it was not clear whether breadfruit was used as a supplement along with the control diet or was processed into a new diet, making it impossible to know what exactly was fed to the mice (Aka et al., 2009). It was also not clear which part of the breadfruit was used. No information about the composition of either the breadfruit or control diets was presented in the paper (Aka et al., 2009). Similar problems can be found in Adepeju 165 et al.’s (2014) weanling albino rats (both sex) study, in which they reported weight loss in weanling rats fed on a breadfruit diet. In the paper, the diet was simply referred to as various ratios of breadfruit, soybeans, and groundnut without any nutritional analysis or method of preparation to establish the baseline of the study (Adepeju et al., 2014). My study is the first complete, fully-designed experiment, and clearly showed that the breadfruit diet did not cause death, clinical discomfort or weight loss. Both male and female mice fed on the breadfruit diet in this study showed a significant increase in body weight/growth rate as compared to the mice fed on the 5LG4 diet (control diet). This finding is interesting for many reasons. BF-fed (breadfruit-fed) mice had higher body weight than 5LG4 fed mice, but it was not reflected in their fat percentages. Male BF-fed mice actually had a significantly lower fat content than 5LG4-fed mice. Although BF-fed mice had higher body weight, their significantly lower fat content excludes the possibility of obesity. The difference in the whole body weight was not associated with weight gain in any particular organ either. The majority of the organs in the BF-fed mice remained the same as the 5LG4-fed mice. BF-fed mice showed a larger body mass than 5LG4 fed mice without significant increase in fat or a particular organ after three weeks trial. Hematology analysis My data showing effects of the BF diet on rodent hematology contradicts previous reports. Adepeju et al. (2014) reported a decrease in percentage hematocrit (red blood cell related parameter) and an increase in the number of white blood cells and platelets in rats fed breadfruit. Aka et al. (2009) reported a significant 166 decrease in the number of white blood cells and red blood cells, and in the percentage of red blood cell related parameters (hemoglobin, hematocrit, MCV, MCH, and MCHC), in male rats fed on raw and partially raw breadfruit diets. Male rats fed on the cooked breadfruit diet had no difference in white blood cell numbers but significantly higher MCV and hemoglobin (Aka et al., 2009). In the current study, differences in white blood cell numbers, red blood cells numbers, red blood cell related parameters or platelets between the male BF- and 5LG4-fed mice were not observed. Significant decreases in major leukocyte cell counts in female BF-fed mice were observed but there is insufficient evidence to determine the cause of this decrease. Mice, as an animal model, experience more biological variations in hematological data than larger animals such as dogs or pigs (Hedrich, 2012). The current data showed that female BF-fed mice had a white blood cell count between 2.10 to 5.90 k/µL and the female 5LG4-fed mice had a range between 4.94 and 15 k/µL. The reported reference range for white blood cells in female CB57/6J mice can be as low as 1.75 k/µL and as high as 14.9 k/µL for 8-12 week old female mice according to Jackson’s laboratory database (Jackson’s Laboratory, 2015). The lowest white blood cell counts found in the BF-fed mice is higher than the reference value and the value from 5LG4-fed mice is higher than the normal range. In addition, the blood samples were collected from the heart through cardiocentesis, which was reported to have lower values than blood samples collected from tails or eye (Nemzek et al., 2001). Further study is required to replicate and validate these results. 167 6.4.2. Intestinal health evaluation Ileum morphology and cytokine response This study is the first study to investigate the impact of the breadfruit diet on the intestinal health of an animal. I found that there was no significant morphology difference between the ileum tissues collected from BF- and 5LG4-fed mice. Mice fed on the breadfruit diet had very similar cytokine responses as mice fed on the 5LG4 diet, except that there was a slightly higher expression of iNOS (<0.5 fold) in the breadfruit diet group. This finding was consistent with our previous in vitro cell model study, in which the breadfruit digestion induced a higher (~1 fold) iNOS production on Caco-2 cells (human epithelial colorectal adenocarcinoma cells) than the wheat digestion under LPS stimulation. LPS is an endotoxin found in Gram-negative bacteria, which are found to be resident in the intestinal tracts of both humans and rodents (van der Waaij et al., 2005). The consistency between the in vitro cell model and in vivo animal study shows the high validity and reliability of the experiment. iNOS is a pro-inflammatory cytokine that can produce nitric oxide, which acts as a cytotoxic agent in the pathological process, and can regulate mucosal barrier function (Aktan, 2004; Hoffman et al., 1997). The production of iNOS in normal mice ileum mucosa has been well demonstrated by Hoffman et al. in 1997, in which they explained that normal mice ileum mucosa express iNOS due to the numbers of bacteria present and this expression can vary depending on the bacterial state. It is possible that BF-fed mice had different bacterial groups resident in the ileum than 5LG4-fed mice. This possibility should be tested further, using DNA sequencing. 168 Colon bacteria The current study examined the major bacterial groups in the colon, which are closely correlated with the bacterial groups in the ileum. The significant differences in the colon bacteria between the diets were found in the two major phyla groups, Bacteroidetes and Firmicutes. The significant increased Bacteroidetes and Firmicutes expressions in BF-fed mice indicate that there is a higher bacteria population present in the BF-fed mice colon. Bacteria diversity is very important in intestinal immunity and it is related to issues like obesity, diabetes, and intestinal diseases (Maslowski and Mackay, 2011; Ley et al., 2005). Bacteroidetes and Firmicutes populations were found to be correlated with obesity in both humans and mice (Ley et al., 2005; 2006). In my study, only very weak correlations (R2<0.1) between fat/lean percentages and Bacteroidetes/Firmicutes expressions were found. The correlations between growth rate and Bacterioidetes and Firmicutes expressions were weak as well (R2<0.2). Future study should further identify the bacterial groups present using DNA sequencing and testing the health impact of breadfruit using an obesity model. 169 6.5. Summary The current data showed that breadfruit diet did not induce adverse impact on mice overall health and growth. The mice fed on the breadfruit diet, both male and female, had a significantly higher body weight/growth rate than the mice fed on the 5LG4 diet without significant increase in fat or any organ after the three week trial. The consistency in the morphology and overall similarity of the cytokine responses in mice fed on the breadfruit and 5LG4 diet both the in vitro cell model and in vivo animal study indicate that the breadfruit diet did not induce any adverse effects or inflammatory responses in the ileum of the mice and it had a similar impact to mice ileum as the 5LG4 diet. Colon bacteria gene analysis indicates that BF-fed mice had different bacterial flora than 5LG4-fed mice. Future research is needed to characterize the effects of a breadfruit diet on the microbiome. 170 Chapter 7. Conclusion The most recent Food and Agriculture Organization (FAO) estimates indicate that about 805 million people in the world were chronically undernourished in 2012-2014. About 791 million of the undernourished population live in developing countries and 349 million undernourished people are found near the equator (FAO et al., 2012; 2014). Although food insecurity, hunger, and malnutrition are ubiquitous and complex problems, when analyzing individual countries, we can find that the lack of local food production is one of the determining factors. For example, in Haiti, half of the population is undernourished. One third of the calorie intake of the population depends on rice and wheat (FAO et al., 2014); however, about 80% of rice and 100% of wheat were imported from the international food market, making the local food system sensitive to international commodities markets. The food import cost to the government is 50% higher than the total merchandise exports of the country in 2008-2010. The common staple foods are unaffordable for much of the population and addressing nutritional deficiencies is crucial to health improvement (FAO et al., 2014). The motivation of this project was to contribute to the development of breadfruit as a sustainable, environmentally-friendly, and high-production agricultural industry in developing countries and tropical areas so that people can gain the ability to feed and support themselves. To date, there have been more than 75,000 trees planted in over 37 countries through this project and the potential of the project for food security has been recognized (Zielinski, 2013). Quality assurance is a prerequisite for the success of breadfruit introduction in impoverished areas. Protein, as one of the most fundamental elements in our diet, plays an important role in human health. The first 171 requirement of a healthy alternative staple crop is the capacity to provide protein in a digestible form (de Onis et al., 1993; FAO, 2013). Evaluation of breadfruit protein quality is necessary for breadfruit product development. To answer the basic question of how much protein breadfruit can produce, I quantified the growth, development, yield, and seasonality of 24 breadfruit cultivars (26 trees) established in Kauai, Hawaii, over a seven-year period from 2006–2012. Individual production profiles were generated for each accessioned cultivar based on major agricultural factors. Across all cultivars of breadfruit (A. altilis), an average of over 200 fruits per year was produced by each tree with an average fruit weight of 1.2 kg. Based on the planting density of 100 trees/ha, this translates to an average projected yield of 13.79 t/ha after 7 years. Hybrids (A. altilis × A. mariannensis) had a higher yield than breadfruit. I found that Ma’afala (commercial cultivar) trees produced fruit within 23 months and in an established orchard, Ma’afala trees will produce 20 t/ha of fruit by 8 years. This will translate to 0.52 t/ha protein yield which is higher than wheat, rice, and potato. The data presented provided a practical forecast for breadfruit agricultural production. To determine the quantity and quality of breadfruit protein, I evaluated the amino acid profile of 49 important breadfruit cultivars (41 Artocarpus altilis and 8 hybrids of A. altilis × A. mariannensis). While significant differences were found between cultivars, all varieties contained a full spectrum of the essential amino acids and are especially rich in phenylalanine, leucine, isoleucine, and valine. Ma’afala contained significantly higher total essential amino acid content than other varieties and higher-quality protein than staples such as wheat, corn, rice, potato, soybean, 172 and yellow pea. Proximate analysis showed that breadfruit can provide a high amount of protein/essential amino acid, but the utilization of the breadfruit protein remained unknown. To understand the digestibility of the breadfruit protein and the possible impacts of breadfruit digestion on intestinal epithelial cells, I developed a multiple-stage enzymatic digestion model, mimicking the human digestion process. The protein analysis before and after the digestion showed that protein from the Ma’afala breadfruit flour was more easily digested than protein from the wheat flour. To quantify the effects of breadfruit digestion on human intestinal health, I applied breadfruit digestion and wheat digestion to Caco-2 cells, and found that breadfruit digestion more positively impacted cell viability than wheat digestion. Both digestions induced similar cytokine responses in Caco-2 cells with some important differences. The higher production of iNOS in breadfruit digestion treated cells under LPS stimulation could be a possible immune defense against bacterial infection. The induction of IL-6 expression by wheat flour and not by breadfruit flour under IL-1β and/or LPS stimulation provides an early indication that breadfruit flour may be better tolerated. To quantify whole body response to the consumption of breadfruit flour, an in vivo study of breadfruit was conducted using C57BL/6 mice as a model. The breadfruit diet did not result in any adverse impact on the overall mice growth and it is applicable for both female and male mice. After the three-week trial, mice fed on the breadfruit diet showed a significantly higher body weight/growth rate than mice fed on the standard diet. I also examined the blood samples from the mice. Hematology analysis 173 between the two diet groups showed that the BF-fed mice (breadfruit diet) had similar red blood cell and platelet profiles as the 5LG4-fed mice (standard diet), supporting evidence that the breadfruit diet did not induce any adverse impact on mice physiology. To test the results obtained from the in vitro cell model study, a close examination of mice intestinal health was conducted. Consistent with the in vitro study results, mice fed on the breadfruit diet showed a very similar cytokine response as mice fed on the standard diet. The higher production of iNOS from the breadfruit treated group was consistent between the in vitro cell model and in vivo animal study. In conclusion, the breadfruit diet did not induce adverse impact on the overall growth of the mice as well as the intestinal health of the mice. 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Thesis/Dissertation
eng
Biochemistry and Molecular Biology
Vancouver : University of British Columbia Library
Attribution-NonCommercial-NoDerivatives 4.0 International
Graduate
Evaluation of breadfruit (Artocarpus altilis and A. altilis X A. mariannensis) as a dietary protein source
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