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Studies on refrigerated fruit products in flexible pouches Speers, Robert Alexander 1982

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STUDIES ON REFRIGERATED FRUIT PRODUCTS IN FLEXIBLE POUCHES by ROBERT ALEXANDER SPEERS B.Sc. (Agr.), U n i v e r s i t y of B r i t i s h Columbia, 1976 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Department of Food Science ~ University of B r i t i s h Columbia We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 1982 (c) Robert Alexander Speers, 1982 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of f-QOh Sc~\5NQ~ The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date A?£\u jig t tfzy^ DE-6 (3/81) - i i -ABSTRACT Selected c u l t i v a r s of apples, peaches, and cherries were prepared as edible f r u i t portions, and preserved i n f l e x i b l e pouches under r e f r i g e r a t i o n . Preserving adjuncts such as sucrose, potassium sorbate, calcium chloride, c i t r i c acid and ascorbic acid were added as concentrated solutions to apple s l i c e s , peach s l i c e s or p i t t e d cherries i n Polyester/Polyethylene or Polyester/ A l foil/Polypropylene pouches that were evacuated and nitrogen-flushed prior to sealing. Some of the pouches were placed d i r e c t l y i n 4°C storage whereas others were heated i n steam or water to provide various blanching treatments pr i o r to r e f r i g e r a t e d storage. At various times up to 12 weeks a f t e r processing, the f r u i t s were examined for physical, chemical, m i c r o b i o l o g i c a l and sensory q u a l i t y . Of the two package structures studied the aluminum f o i l - c o n t a i n i n g pouch proved superior to the Polyester/Polyethylene laminate i n preserving f r u i t q u a l i t y . Results for a series of mild thermal blanch treatments varied with f r u i t type i n terms of microbial s t a b i l i t y and sensory q u a l i t y a t t r i b u t e s . For apples, blanching to a center temperature of 80°C proved to be the most s a t i s f a c t o r y , whereas 70°C was optimal for peach q u a l i t y . Cherries, blanched to a center temperature of 80°C, were of good microbial s t a b i l i t y . Both. Golden Delicious and Spartan c u l t i v a r s prepared as apple s l i c e s were found to have good f l a v o r , color and t e x t u r a l c h a r a c t e r i s t i c s a f t e r 12 weeks of r e f r i g e r a t e d storage. Of the three peach c u l t i v a r s examined, Fairhaven and Redhaven freestone peaches produced s l i c e s of good q u a l i t y a f t e r processing and r e f r i g e r a t e d storage of 12 weeks. Fortuna, a clingstone c u l t i v a r , had an unsuitable rubbery texture a f t e r the storage period. Lambert sweet cherries - i i i -and Montmorency sour cherries proved to be unsuitable because of problems a r i s i n g from microbial growth and loss of textural q u a l i t y . In summary, i t was determined that Golden Delicious and Spartan apple c u l t i v a r s and Fairhaven and Redhaven peach c u l t i v a r s can be processed into high q u a l i t y r e f r i g e r a t e d f r u i t products suitable for storage i n aluminum f o i l - c o n t a i n i n g f l e x i b l e pouches at 4°C for up to 12 weeks. - i v -TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS i v LIST OF TABLES v i i LIST OF FIGURES i x ACKNOWLEDGEMENTS x INTRODUCTION 1 LITERATURE REVIEW 3 A) R e f r i g e r a t e d F r u i t Products 3 , 1) Apples 3 2) Peaches 4 3) C h e r r i e s 5 B) P r e s e r v a t i o n of F r u i t Q u a l i t y 5 1) Color 5 2) F l a v o r 7 3) Texture 8 4) M i c r o b i a l s t a b i l i t y 10 C) Benzaldehyde D e t e c t i o n 10 EXPERIMENTAL METHODS 12 A) Experimental Design and Processing Procedures 12 1) Apple t r i a l s 12 2) Peach t r i a l s 18 3) Cherry t r i a l s 20 B) Blanch Determinations 22 C) Chemical A n a l y s i s 24 1) pH determination 24 2) T o t a l a c i d i t y 24 3) Soluble s o l i d s 24 4) G a s - l i q u i d chromatography 25 - v -D) P h y s i c a l Methods 1) Magness-Taylor pressure t e s t 2) S i n g l e blade shear 3) Cherry t e x t u r e measurement A) Color 5) Drained weight E) M i c r o b i o l o g i c a l A n a l y s i s F) Sensory A n a l y s i s G) S t a t i s t i c a l A n a l y s i s RESULTS AND DISCUSSION A) Blanching Studies B) Packaging Studies C) Apple Studies 1) Gd-I t r i a l 2) Gd-II t r i a l 3) Gd-III and Sp-I t r i a l s A) Summary of apple t r i a l s D) Peach Studies 1) Fo-I and Fh-I t r i a l s 2) Fh - I I and Rh-I t r i a l s 3) GLC a n a l y s i s 4) Summary of peach t r i a l s E) Cherry Studies CONCLUSIONS A) Blanching Studies B) Packaging Studies C) Apple Studies D) Peach Studies E) Cherry Studies F) Summary - v i -Page SUGGESTIONS FOR FURTHER RESEARCH , 79 LITERATURE CITED 81 APPENDIX 86 A) Sensory Panel Forms 86 1) Processed apple s l i c e s 86 2) Processed peach s l i c e s 88 3) Processed cherry s l i c e s 91 - v i i -LIST OF TABLES Table Page I Packing Dates and F r u i t C u l t i v a r s Studies 13 I I Gd-II Apple Experimental Treatments 17 I I I Gd-III and Sp-I Apple Experimental Treatments 17 IV Fh-I and Fo-I Peach Experimental Treatments 21 V La-I and Mo-I Cherry Experimental Treatments 21 VI Blanching Conditions f o r Each F r u i t T r i a l 32 V I I A n a l y t i c a l Values of Raw and Processed Gd-I Apple S l i c e s 36 V I I I Pooled Means of Sensory Color Scores from Gd-I Apple 38 S l i c e s IX Gd-I Apple S l i c e OTMS and Sensory Texture Results 40 X A n a l y t i c a l Values of Processed Gd-II Apple S l i c e s 42 XI Gd-II Hunterlab 'L' Values of Each Time, Blanch and 44 Treatment Combination X I I Gd-II Apple S l i c e I n s t r o n and Sensory Texture Results 45 X I I I A n a l y t i c a l Values of Processed Gd-III and Sp-I Apple 48 S l i c e s XIV Pooled Gd-III and Sp-I Hunterlab 'L' Values at 3 Months 49 XV Gd-III and Sp-I Sensory Texture Means 51 XVI Gd-III and Sp-I Pooled Sensory Taste Means 52 XVII Sensory-Overall A c c e p t a b i l i t y Scores f o r Gd-III and Sp-I 53 T r i a l s XVIII Fo-I and Fh-I A n a l y t i c a l Values at 3 Months 55 XIX Fo-I and Fh-I Hunterlab 'L' Values at 3 Months 57 XX Fo-I and Fh-I Texture Data Results 59 XXI Pooled Sensory Taste Fo-I and Fh-I Results 60 - v i i i -Table Page XXII Pooled Sensory Almond Fo-I and Fh-I Results 61 XXIII Fo-I and Fh-I Sensory O v e r a l l A c c e p t a b i l i t y Results 62 XXIV Fh-II and Rh-I A n a l y t i c a l Values at 3 Months 64 XXV Pooled Fh-II and Rh-I Hunterlab L.Values 65 XXVI Results of Fh-II and Rh-I Benzaldehyde A n a l y s i s by 69 Treatment and C u l t i v a r XXVII Mo-I and La-I M i c r o b i a l Results at 3 Months 72 XXVIII Mo-I and La-I Pooled A n a l y t i c a l Values 73 - i x -LIST OF FIGURES Figure Pagi I Flowchart of Apple Proc e s s i n g P l a n (Gd-I) 15 I I Flowchart of Peach Processing Plan (Fh-I and Fo-I) 19 I I I Flowchart of Cherry Processing Plan (La-I and Mo-I) 23 IV Diagram of C o - D i s t i l l a t i o n Apparatus 26 V A T y p i c a l Gas-Liquid Chromatogram Obtained During GLC A n a l y s i s of Peach Samples (Fh-II Raw Sample) 67 ACKNOWLEDGEMENTS The author wishes to express h i s a p p r e c i a t i o n for a s s i s t a n c e i n t h i s study to: Dr. M.A. Tung my t h e s i s s u p e r v i s o r , Dr. W.D. Powrie, and Dr. J . Vanderstoep, a l l of the Food Science Department, who provided advice and encouragement. Mr. J.A. K i t s o n and s t a f f of the A g r i c u l t u r e Canada Research S t a t i o n , Summerland who provided m a t e r i a l s , equipment and advice. Mrs. C A . Reid of Sun-Rype Products L t d . , Kelowna for advice and m a t e r i a l s . Miss L. Robinson and Miss M. Yee of the Food Science Department who provided t e c h n i c a l a s s i s t a n c e . This study was also supported f i n a n c i a l l y by the B r i t i s h Columbia M i n i s t r y of A g r i c u l t u r e and Food. - 1 -INTRODUCTION Over the past several years the food industry has developed several preservation methods aimed at providing greater v a r i e t y and continuity of the food supply for f r u i t crops, the main processed forms have been thermally . processed canned and frozen products. The market share of processed f r u i t has continued to grow due to i t s year round a v a i l a b i l i t y and convenience (66). However, thermally processed f r u i t s are generally of lower f l a v o r , texture, color, and n u t r i t i v e q u a l i t y than fresh f r u i t . In addition, frozen f r u i t products have poor texture and are subject to f l u i d loss when thawed. The development of s l i c e d r e f r i g e r a t e d f r u i t products has been stimulated by the p o t e n t i a l advantages of extended a v a i l a b i l i t y and greater convenience compared with fresh f r u i t , and higher q u a l i t y compared with thermally processed or frozen counterparts. A number of r e f r i g e r a t e d f r u i t products have been marketed i n the United States, such as apples, peaches, c i t r u s f r u i t s and even cantaloupes which have been packed in glass containers. Apples and peaches marketed i n this form have been shown to have shelf l i v e s of up to 8 and 20 weeks, respectively (66). Refrigerated f r u i t products of this type have not been av a i l a b l e commercially i n B r i t i s h Columbia; however, int e r e s t has been shown and preliminary research and development has been carried out by both Sun-Rype Products Ltd., Kelowna (48) and the Department of Food Science, University of B.C., i n cooperation with the Agriculture Canada Research Station at Summer-land (44). Since there appears to be a demand for this type of f r u i t product and the use of f l e x i b l e pouches appears to o f f e r advantages of convenience, along with reductions i n cost and weight, this study was i n i t i a t e d on - 2 -r e f r i g e r a t e d f r u i t products i n f l e x i b l e pouches. The objective of this study was to examine the f e a s i b i l i t y of producing prepared apple, peach, and cherry products with r e f r i g e r a t e d shelf l i v e s of up to 3 months and acceptable q u a l i t y when compared to canned and frozen f r u i t s . - 3 -LITERATURE REVIEW A) Refrigerated F r u i t Products Numerous studies have been carried out i n the United States and Canada on storage c h a r a c t e r i s t i c s of r e f r i g e r a t e d f r u i t products. C h i l l e d c i t r u s f r u i t products are a v a i l a b l e i n the United States, and t h e i r market share continues to expand (66). Research on other f r u i t s has centered mainly on apples and peaches. Refrigerated apple s l i c e s have been studied by B o l i n and co-workers (7), Pointing et a l . (42,43), Lazar and Hudson (30) and Reid (48). A number of studies on r e f r i g e r a t e d peach s l i c e s have also been reported by Robinson and H i l l s (50), Van Blaricom (58), P o r r i t t (44), Woodroof et a l . (65), Reid (48) and Bates and co-workers (4). With the exception of the work of P o r r i t t and Reid a l l this research has been c a r r i e d out on apple and peach c u l t i v a r s common i n the United States. Besides these two f r u i t s , both sweet and sour cherries may have p o t e n t i a l for marketing as r e f r i g e r a t e d f r u i t products in B r i t i s h Columbia (48). 1) Apples Early research on storing apple s l i c e s at r e f r i g e r a t e d temperatures was reported by B o l i n et a l . i n 1964 (7). These workers were pr i m a r i l y concerned with improving the q u a l i t y of the s l i c e s for the bakery trade. They found that two 45 second dips i n 0.25% NaHS03 and 0.2% K^PO^ improved apple s l i c e texture when compared to a NaHSO^ dip alone. Later work by Ponting, Jackson and Watters (42,43) concentrated on extending the shelf l i f e of r e f r i g e r a t e d apple s l i c e s from 3 to 9 weeks. They found that Golden Delicious apple s l i c e s could be preserved for 8 weeks by - k -dipping i n a pH 7 s o l u t i o n of 1% ascorbic acid and 0.1% calcium (as CaCl^) and storing i n heat-sealed polyester bags at 4°C. No microbial analyses were reported; however, yeast and mold growth appeared to be the l i m i t i n g factor i n the product shelf l i f e . 2) Peaches. Since the q u a l i t y d e t e r i o r a t i o n of fresh peaches is rapid, considerable research has been devoted to studying r e f r i g e r a t e d storage of peach c u l t i v a r s . The peach is a r e l a t i v e l y d e l i c a t e f r u i t which deteriorates r a p i d l y on ripening (50). Robinson and H i l l s noted that peach s l i c e s could be preserved by sorbate, sugar and heat treatment for up to 90 days before microbial spoilage began. Van Blaricom studied this method of preservation over a 3 year period using the Elberta c u l t i v a r (58). He developed a process whereby peaches could be stored at -1°C i n a syrup consisting of 25% sugar, 0.05% ascorbic acid, 0.05% c i t r i c acid, 0.05% sodium benzoate and 0.0165% sodium meta b i s u l f i t e . Upon storage, however, these unblanched peaches developed an almond-like f l a v o r . It was found that blanching the peaches to 57°C or higher prevented this almond-like flavor development. In 1969, Heaton and co-workers (22) reported on t h e i r work with r e f r i g -erated peach s l i c e s . They found ascorbic acid to be an e f f e c t i v e antioxidant, and sodium benzoate to be the most e f f e c t i v e microbial i n h i b i t o r . A number of v a r i e t i e s were examined and i t was found that flavor and texture were the main q u a l i t y a t t r i b u t e s affected by the choice of c u l t i v a r . The factor l i m i t i n g storage of s l i c e d peaches was the appearance of a seedy or b i t t e r almond-like flavor which became stronger with increased storage time. In 1975, Woodroof et a l . (65,66) published a processing method s i m i l a r to Van Blaricom's (58) for preparing processed r e f r i g e r a t e d peaches. Bates and - 5 -others (4) analyzed the microbial s t a b i l i t y of r e f r i g e r a t e d peaches i n f l e x i b l e pouches. They found that peaches stored at 2°C a f t e r a 86°C blanch retained good q u a l i t y (4). In B r i t i s h Columbia, research on r e f r i g e r a t e d peach s l i c e s has been c a r r i e d out by P o r r i t t (44) and Reid (48). Both found that unblanched peaches stored at 4°C developed almond-like flavors a f t e r storage for 3 weeks. 3) Cherries In contrast to peaches, very l i t t l e research has been undertaken to develop r e f r i g e r a t e d cherry products. Rushing and Senn (52) reported that maraschino cherries could be successfully incorporated into a r e f r i g e r a t e d f r u i t salad. Reid (48) c a r r i e d out preliminary work with sour cherries and found that they could be preserved for 7 months but that excessive f l u i d loss from the tissue detracted from t h e i r a c c e p t a b i l i t y . B) Preservation of F r u i t Quality 1) Color Browning of s l i c e d f r u i t occurs soon a f t e r the f l e s h is bruised or cut. This enzymatic browning is the r e s u l t of the actions of oxygen and polyphenol oxidase (PPO) acting on a suitable phenolic substrate (23). This d i s c o l o r a t i o n can be c o n t r o l l e d by either l i m i t i n g the oxygen present, by reducing levels of available substrate or by i n a c t i v a t i n g the enzyme PPO. Oxygen levels may be minimized by using a gas f l u s h , such as nitrogen, when packaging prepared f r u i t s i n f l e x i b l e packages. Also, ascorbic acid can be used to retard oxidation and thus browning by i t s reducing action on o-quinones. Embs and Markakis (14) have presented evidence that SO^ also acts by complexing o-quinones. Ascorbic acid was employed by Ponting et a l . - 6 -(43) and by Heaton et a l . (22) for preserving apples and peaches, using l e v e l s of 0.05% and 0.1%, re s p e c t i v e l y . In Canada, ascorbic acid is permitted in canned peaches at 0.055% and in unstandardized foods as needed for good manufacturing practise (2). A l t e r n a t e l y , blanching can be used to reduce or prevent browning by i n a c t i v a t i n g f r u i t PPO. Dimick et a l . (11) found PPO i n apple and peach purees (at pH 3.1 and 3.5 respectively) to be completely inactivated by heating to 82°C for 9 seconds, 76°C for 24 seconds or 72°C for 2 minutes. Studies with sour (53) and sweet cherries (5) have shown that cherry PPO can be inactivated by a heat treatment at 100°C for 60 seconds ( pH 3.5) and at 75°C for 1.9 minutes (50% i n a c t i v a t i o n , pH unknown) respectively. The addition of an acid such as c i t r i c acid can also be used to retard browning. This occurs because the pH i s lowered from normal and away from the range of PPO's optimum a c t i v i t y . The optimum pH for PPO a c t i v i t y has been reported as 7.5 to 8.2 (40) for apple, 5.2 and 7.3 (54), for clingstone peaches, 6.2 (38), 6.8 to 7.0 (64), for freestone peaches, 4.4 and 6.2 (41)' and as 4.7 for sour cherries (5). In addition, c i t r i c acid i s believed to chelate the copper present i n PPO, thus reducing i t s a c t i v i t y . At the present time, c i t r i c acid is allowed in foods according to good manufacturing practise (2). Sodium chloride can also be used to prevent browning during processing (9), and calcium chloride has been found to have a s y n e r g i s t i c e f f e c t with ascorbic acid i n preventing browning (43). Other color changes i n f r u i t , such as non-enzymatic browning tends to occur at temperatures above 20°C (24). In peaches, carotenoid compounds can be lost during processing (23). However these losses are usually low when compared to changes due to enzymatic browning. In cherries, the p r i n c i p a l - 7 -color components are anthocyanin. These compounds can be decolorized or polymerized with other polyphenols to form brown pigments. Anthocyanin color i s known to be very pH dependent (47,63). 2) Flavor F r u i t flavor i s a combination of the taste and aroma of the f r u i t . Although i t i s known that simple tastes of f r u i t can be influenced by acid/ sugar r a t i o , the study of f r u i t aroma ( i . e . i t s v o l a t i l e s ) i s far from complete. In the l a s t two decades the use of g a s - l i q u i d chromatography (GLC) coupled with mass spectroscopy (MS) has lead to the i d e n t i f i c a t i o n of many f r u i t f l avor compounds (15). These v o l a t i l e constituents can be labeled as mainly esters, alcohols and aldehydes. Unfortunately, very l i t t l e information is available concerning flavor d e t e r i o r a t i o n during processing and storage (23). Many fresh f r u i t flavors can be l o s t by decomposition during heating and storage. In addition, other flavors can occur due to enzymatic and non-enzymatic changes during storage. Apple v o l a t i l e s have been analyzed by Flath et a l . (18), Williams et a l . (62), Dirimck et a l . (12) and many others using GLC. Williams and co-workers found that hexanal, ethyl 2-methyl butyrate, hexyl 2-methyl butyrate, hexyl acetate and 4-methoxyallylbenzene were s i g n i f i c a n t aroma compounds i n apples. Peach v o l a t i l e s have been studied by Do et a l . (13) and Spencer et a l . (57). Spencer et a l . found that Y~la ctones are important contributors to fresh peach aroma, and benzaldehyde is known to contribute s i g n i f i c a n t l y to peach fl a v o r (13,23,34,56,57) . Benzaldehyde concentrations increase in r e f r i g e r a t e d peaches, causing a disagreeable almond-like flavor (22,34,44). - 8 -Two benzyaldehyde formation pathways are known to e x i s t i n f r u i t s . The f i r s t involves the enzyme 8 -glucosidase breaking down amydlin to glucose benzaldehyde and hydrocyanic acid. Haismen and Knight (21) studied the heat s t a b i l i t y of B-glucosidase and found that i t was 90% inactivated a f t e r heating to 80°C for 1.2 minutes. The second pathway involves the synthesis of benzaldehyde from benzoyl CoA, and was proposed by Croteau (10) to function i n the -production of benzyl benzoate found i n cranberry j u i c e . In cherries, benzaldehyde, methanol, ethanol and geraniol have been i d e n t i f i e d as contributing to the v o l a t i l e flavor i n cherries; however, no c h a r a c t e r i s t i c compound has been associated with cherry aroma. 3) Texture The firmness of f r u i t s such as apples, peaches and cherries is dependent i n part on the nature of the pectic substances found i n the middle lamella of parenchyma c e l l s . These pectic substances are made up of polygalacturonic acid u n i t s , and are susceptible to breakdown by polygalacturonase" (PG) and pectinmethylesterase (PE) (16). Polygalacturonase has been shown to increase i n a c t i v i t y as f r u i t s ripen along with a corresponding loss of firmness. This is presumably due to a cleavage of the polygalacturonic acid. On the other hand, pectinmethylesterase has been shown to decrease in a c t i v i t y with f r u i t ripening. It i s believed that PE cleaves methyl side chains of the galacturonic acid polymer (16). Many f r u i t s can be firmed by adding calcium s a l t s to them. This is due to the calcium ion forming s a l t bridges between polygalacturonic acids at points where PE has cleaved methyl groups. In Canada, calcium i s allowed i n foods up to a l e v e l of 0.026% as a firming agent (2). - 9 -Lee and Wiley (33) characterized apple PE and found i t to have an optimum a c t i v i t y near pH 7.0 and a temperature of 55°C. These researchers advocated a c t i v a t i n g PE i n apples to a s s i s t i n calcium binding thus firming the f r u i t (61). P o r r i t t and L i d s t e r (45) and L u i (39) have shown that apples could be given a post-harvest heat treatment (at 38°C) to increase firmness i n cold storage. Presumably t h i s increase i n firmness i s due to pectin s a l t bridging a f t e r PE action. However, P o r r i t t and L i d s t e r (45) suggested that heating decreased PG a c t i v i t y , causing less polygalacturonic acid cleavage and thus greater firmness. L i d s t e r et a l . (37) and Yee (67) studied the e f f e c t of post-harvest heating of apples p r i o r to storage and heat processing. They found that the heat treatment gave firmer apple s l i c e s than the control although color was somewhat darker and t i t r a t a b l e a c i d i t y decreased. Ponting et a l . found that calcium improved the texture of r e f r i g e r a t e d apple s l i c e s texture stored for 4 weeks at 1°C. Very l i t t l e information i s available on the texture of peach products. I t is known that PG a c t i v i t y i s increased as peaches mature (16). Also, Hulme (23) has noted that methyl e s t e r i f i c a t i o n of peach c e l l wall pectins decrease, thereby i n d i c a t i n g PE a c t i v i t y . Cherry texture, e s p e c i a l l y of sour (red-tart) cherries, has been i n v e s t i -gated by LaBelle and Moyer (26), LaBelle (25), Van Buren (59) and others. Van Buren (59) has found that cherry PE could be activated by heating to 65°C for 10 minutes, or by holding at 40°C for 30 minutes. He found that heating along with using a calcium s a l t gave a firmer canned product when compared to controls. - 10 -In fresh sweet cherries, L i d s t e r et a l . (35,36) reported that calcium le v e l s were p o s i t i v e l y correlated with firmness and that the addition of calcium reduced surface damage. The formation of calcium s a l t bridges between galacturonic acid units was put forward as the reason for increased cherry firmness. 4) M i c r o b i a l S t a b i l i t y The microbial s t a b i l i t y of f r u i t products was studied by Robinson and H i l l s i n 1959 (50). They found that 0.048% sodium sorbate and a mild heat treatment (120°C for 5 mins prevented microbial growth for more than 90 days. Rushing and Senn (52) stored c i t r u s salads for 12-16 weeks at -1°C and found sodium benzoate and sodium sorbate, at l e v e l s of 0.05 and 0.11%, res p e c t i v e l y , prevented spoilage. Bates et a l . (4) prepared m i c r o b i o l o g i c a l l y stable, r e f r i g e r a t e d peach halves using a pasteurizing heat treatment of 70°C for 8 minutes. Gomez et a l . (20) used heat treatments of 5-10 minutes at 89°C to prepare mangoes for r e f r i g e r a t e d storage, with no microbial problems reported. Sorbic acid is most often used as a microbial i n h i b i t o r due to i t s neutral taste (1) and the fact that i t is e f f e c t i v e over a wide pH range (49). Smith et a l . (55) studied the e f f e c t of pH on yeast growth i n the presence of sorbic acid. They found that 0.05% sorbate e f f e c t i v e l y i n h i b i t e d yeast growth below a pH of 4.0. C) Benzaldehyde Detection Benzaldehyde has been known to cause o f f - f l a v o r s i n peaches and has been detected in other f r u i t s as well. The extraction process usually involves v o l a t i l e concentration, and analysis i s usually by GLC. V o l a t i l e concentration - 11 -may be c a r r i e d out by vacuum d i s t i l l a t i o n with c o l l e c t i o n of v o l a t i l e s i n a low temperature trap. This d i s t i l l a t e can then be p u r i f i e d and analyzed by GLC (34). Newer methods (18,19,57) have used a c o - d i s t i l l a t i o n procedure described by F l a t h and Forrey (19). This apparatus continuously condenses both sample v o l a t i l e s with water and a solvent vapor. It returns sample v o l a t i l e s and solvent to the solvent f l a s k and sample water to the sample f l a s k . Over time the solvent w i l l p r e f e r e n t i a l l y c o l l e c t sample v o l a t i l e s which can be concentrated by solvent evaporation for GLC analysis. Columns packed with Carbowax 20M have been used for peach v o l a t i l e component analysis (56,57). - 12 -EXPERIMENTAL METHODS A) Experimental Design and Processing Procedures This project was divided into three sections based on the f r u i t studied. Within each section a number of t r i a l s were c a r r i e d out over the project's 1.5 year experimental term. A t o t a l of 10 t r i a l s were carried out involving 3 apple, 3 peach and 2 cherry c u l t i v a r s . Table I displays the f r u i t s and c u l t i v a r s studied and the time during which the t r i a l s were conducted. During the 1979 summer season the t r i a l s involved three-way f a c t o r i a l s , studying the e f f e c t s of processing and chemical treatment, time, and package type on sensory, textural and color a t t r i b u t e s of the products. In addition, other q u a l i t y factors such as m i c r o b i o l o g i c a l s t a b i l i t y , pH, t o t a l a c i d i t y , and drained weight, and soluble solids were monitored. A f t e r analyzing the r e s u l t s of these t r i a l s further studies were under-taken with apples and peaches between November 1979 and January 1981. These t r i a l s mainly involved two-way f a c t o r i a l s (excluding Gd-I, Figure 1) which tested the e f f e c t s of chemical processing and treatment, and c u l t i v a r , on the f r u i t q u a l i t y a t t r i b u t e s . 1) Apple t r i a l s The f i r s t apple t r i a l (Gd-I) studied the e f f e c t s of three d i f f e r e n t blanch treatments, package permeability to l i g h t and oxygen, and time, on apple s l i c e q u a l i t y . These apples were Golden Delicious that had been in cold storage for eight months. Aft e r peeling, coring and s l i c i n g , the s l i c e s were held i n a 0.1% s a l t (NaCl) solution and then dipped for 3 minutes each i n 0.1% calcium (as CaCl 2.2H 20), and a 0.03% s u l f u r dioxide (as N a ^ O ^ solutions. The blanch treatments were 30 and 60 seconds i n steam and 60 - 13 ~ Table I . Packing Dates and F r u i t C u l t i v a r s Studied C u l t i v a r D a t e Apple Peach Cherry Golden Spartan Fairhaven Redhaven Fortuna Lambert Montmorency Delie ious May 1979 June J u l y Aug Sept Oct Nov Dec Jan 1980 Feb Mar A p r i l May June J u l y Aug Sept Oct Nov Dec Jan 1981 Gd-I La-I Mo-I Fh-I Gd-II Fo-I Fh-II Rh-I Gd-III Sp-I - 14 -seconds i n b o i l i n g water giving s l i c e center temperatures of about 65°, 80° and 80°C r e s p e c t i v e l y . The 80°C temperatures were chosen based on thei r a b i l i t y to inacti v a t e polyphenol oxidase and the 65°C blanch was intended to test whether flavor and texture would be improved at a milder heat treatment without color d e t e r i o r a t i o n . The s l i c e s were packed with 0.05% sorbate (as K C ^ O ^ , 0.05% ascorbic acid, 0.35% c i t r i c acid (as C^HgO^.H^O) and 5.0% sucrose based on the sample weight of 200 grams. These adjuncts were dissolved i n 28 ml of water and added with the apple s l i c e s to pouches constructed of an aluminum f o i l laminate and clear Polyester/Polyethylene. The aluminum f o i l pouches were obtained from Continental Can Ltd., Canada and were 15.2 x 23.4 cm made of a 12 um Polyester/9 Um Aluminum f o i l / 7 6 Um Polypropylene laminate. The 25 Um Polyester/51 um Polyethylene transparent pouches were obtained from DRG Packaging Ltd., Vancouver. They were 12.5 cm wide and 24 cm long. A f t e r the apple s l i c e s had been dipped and blanched, 200 g were added to the pouch along with the chemical adjuncts and sealed with a Multivac vacuum/ gas sealer. The actual sealing process began with evacuation of headspace a i r to 0.1 kPa followed by nitrogen flushing to 0.25 kPa and heat sealing. The packages were stored at 4°C. The polyethylene pouches were stored e i t h e r i n the dark or under constant fluorescent l i g h t to simulate supermarket conditions. A l l pouches were assessed at 2, 4 and 10 weeks. Figure 1 shows a flow chart of the Gd-I t r i a l s . In the second apple t r i a l (Gd-II), the e f f e c t s of heat and chemical adjuncts on Golden Delicious apple s l i c e q u a l i t y were studied. These apples were processed d i f f e r e n t l y from the Gd-I t r i a l , with the apples being peeled, - 15 -Figure I. Flowchart of Apple Processing Plan CGd-I) Cold Storage Peeling and Coring 1% NaCl Dip + S l i c i n g 0.1% C a C l 2 + 0.03% S0 2 Dip Blanching ( i . e . : e i t h e r control, 65°C or 80°C steam blanch or 80°C l i q u i d blanch) Packing in Pouches (with 0.05% Sorbate 0.05% Ascorbic Acid 0.35% C i t r i c Acid 5% Sucrose) N 2 flush and sealing Storage at 4oc i n dark or under fluorescent l i g h t - 16 -s l i c e d and cored and held i n a 1% s a l t solution u n t i l being packaged with various chemical adjuncts. Once sealed (using the method outlined in the Gd-I t r i a l ) , h a l f the pouches were given a blanch treatment s u f f i c i e n t to heat the apple s l i c e center to 80°C. Only the aluminum f o i l pouches described e a r l i e r were used. The chemical adjuncts were again added i n water at a l e v e l of 28 ml per pouch. The adjuncts added were: 0.1% ascorbic acid, 0.05% sorbate (as KC,H_0„), 6% sucrose and varying levels of calcium (as CaCl o.2H o0) and c i t r i c acid (as C,Ho0-, .H_0). The chemicals were a l l added as a D O / / percentage of the 200 grams of f r u i t contained i n each pouch. Since this Gd-II t r i a l was designed to study the e f f e c t s of heat, high and low levels of c i t r i c acid and calcium, the eight treatments were set up as shown i n Table II. Af t e r storage for 12 weeks at 4°C the apples were examined for sensory and instrumental q u a l i t y . In addition, pH, t o t a l a c i d i t y , drained weight, microbial s t a b i l i t y and soluble s o l i d s were monitored. The l a s t apple t r i a l tested both Golden Delicious (Gd-IIl) and Spartan (Sp-I) c u l t i v a r s . In these t r i a l s the e f f e c t s of adding apple fl a v o r i n g s , apple j u i c e and blanching were studied. The f l a v o r i n g added was R-10305, natural Apple Flavor, Lot 10/86 obtained from Givaudan Ltd., Vancouver. This f l a v o r i n g was selected and the l e v e l of addition set by bench top testing i n an adjunct-water s o l u t i o n i d e n t i c a l to the one added to the apple s l i c e s . The apple ju i c e used was a clear blend of 50% Red Delicious and 50% Macintosh c u l t i v a r s obtained from Sun-Rype Ltd., Kelowna. The four treatments set up for both Gd-III and Sp-I t r i a l s are shown in Table I I I . Both the control and flavor treatments contained 0.1% ascorbic acid, 0.05% sorbate, 0.05% calcium, 0.20% c i t r i c acid and 5% sucrose. The j u i c e treatments, however, contained only j u i c e and ascorbic acid. - 17 -Table II. Gd-II Apple Experimental Treatments Center Temperatrue Treatment of Blanched S l i c e Ca Level (%) C i t r i c Acid Level (%) Control (C) n i l 0. .025 0.25 Heat (H) 80°C 0. .025 0.25 Calcium (Ca) n i l 0 .05 0.25 Ca-H 80°C 0, .05 0.25 C i t r i c Acid ( C i t ) n i l 0 .025 0.50 Cit-H 80°C 0 .025 0.50 Cit-Ca n i l 0 .05 0.50 Cit-Ca-H 80°C 0 .05 0.50 Table I I I . Gd-III and Sp-I Apple Experimental Treatments Center Temperature Flavoring Treatment of Blanched S l i c e % Adjunct C a r r i e r Adjuncts Used** Control 80°C n i l water A, C, Ca, S, Su Flavor 80°C 0.056 water A, C, Ca, S, Su Juice n i l n i l j u i c e A Juice + Heat 80°C n i l j u i c e A *% w/w of f r u i t assuming 1 ml f l a v o r i n g = 1 g **where A = ascorbic acid, C = c i t r i c acid, Ca = calcium, S = sorbate, Su = sucrose - 18 -The processing of these two t r i a l s was i d e n t i c a l to the Gd-II processing with the exception of adjuncts added. As i n the previous work a l l samples were stored at 4°C u n t i l examined at 12 weeks. 2) Peach t r i a l s The f i r s t peach t r i a l s involved two types of commercial peaches: a freestone c u l t i v a r , Fairhaven (Fh-I) and a clingstone c u l t i v a r , Fortuna (Fo-I). The e f f e c t s of d i f f e r e n t blanch center temperatures (55, 65 and 75°C), calcium, package types, and storage times on q u a l i t y a t t r i b u t e s were examined. Table IV shows the treatment flow sheet for both the Fh-I and Fo-I t r i a l s . Figure II outlines the processing procedure used to package the peaches. The f r u i t was either steam peeled or lye peeled (by pouring 3% KOH over steamed halves) for 1 minute a f t e r p i t t i n g . After peeling, the peaches !were washed i n cold water and held i n a 0.1% solution of ascorbic acid while' s l i c i n g . Both t r i a l s were then packaged with the following chemical adjuncts: 0.1% ascorbic acid, 0.05% sorbate, 0.5% c i t r i c acid, 0.026% calcium (optio n a l ) , and 5% sucrose. The f r u i t packaging procedure was i d e n t i c a l to the one f o l -lowed i n the Gd-I t r i a l . As i n the second apple t r i a l only aluminum f o i l -containing pouches were used. A f t e r packaging the peaches were blanched as necessary and stored at 4°C. Quality a t t r i b u t e s were measured at 2, 4 and 12 weeks. In the second set of peach t r i a l s two freestone c u l t i v a r s , Fairhaven (Fh-II) and Redhaven (Rh-I) were examined. Both t r i a l s were divided into two treatments, a control and a flavor adjunct treatment. The peaches were processed as the Fh-I t r i a l with a blanch process to heat the s l i c e center to 70 C. In addit ion, only aluminum f o i l - c o n t a i n i n g pouches were used. The chemical adjuncts were added i n 28 ml of water per 200 grams of f r u i t at the - 19 -Figure I I . Flowchart of Peach Processing Plan (Fh-I and Fo-I) Cold Storage Steam Peeling (Rh-I) Lye Peeling with 3% KOH (Fo-I) Cold Wash 0.1% Ascorbic Acid Dip + S l i c i n g Packing in Pouches with (0.05% Sorbate 0.1% Ascorbic Acid 0.05% C i t r i c Acid 0.026% Calcium (optional) 6% Sucrose) N 2 Flush + Sealing Blanching at 55, 65 + 75°C Storage at 4°C - 20 -following l e v e l s : 0.1% ascorbic acid, 0.026% calcium, 0.4% c i t r i c acid, 0.05% sorbate and 6% sucrose. The fl a v o r i n g added was Natural Peach Flavor, R10,270, Lot 4/80 obtained from Givaudan Ltd., Vancouver. The type and l e v e l of addition (0.056% assuming f l a v o r i n g density of 1 g/ml) was decided by bench top testing i n the adjunct solution added to the peach s l i c e s . A f t e r the peaches were packaged and blanched they were stored at 4°C for analysis at 12 weeks. Gas-liquid chromatographic analysis was c a r r i e d out on products stored at 4°C for 12 weeks and then kept at -35°C u n t i l analysis. 3) Cherry t r i a l s Two cherry t r i a l s were carried out using Lambert (La-l) and Montmorency (Mo-l) c u l t i v a r s selected as representatives from the sweet and sour v a r i e t i e s . These t r i a l s investigated the e f f e c t of time, package type, ascorbic acid, a blanch intended to improve texture, and a blanch intended to improve color. Table V shows the treatments given these cherries to measure the e f f e c t of ascorbic acid and the two blanching treatments. The cherries were washed, given an optional 'texture' blanch i n a 60°C water bath for 20 minutes and p i t t e d using a p i l o t plant Dunkley p i t t e r . This treatment was based on reports (26,59) that indicated that a heat treatment of this type would give improved texture by pectinmethylesterase action. The pi t t e d cherries were packaged in the f o i l containing pouches mentioned previously. As with the other f r u i t s the chemical adjuncts 0.0.26% calcium, 0.05% sorbate, 8% sucrose and 0.05% ascorbic acid (optional) were added in 28 ml of water to 200 g of the f r u i t per package. The cherries were packaged as described e a r l i e r and then given a blanchto improve color (optional) by b o i l i n g i n water u n t i l a cherry center temperature of about 85°C was reached. These pouches were then cooled and stored at - 21 -Table IV. Fh-I and Fo-I Peach Experimental Treatments Treatment Center Temperature of Blanched S l i c e Calcium Added % Control 55 65 75 No Calcium n i l 55 65 75 n i l 0.026 0.026 0.026 0.026 0.0 Table V. La-I and Mo-I Cherry Experimental Treatments Treatment Texture Blanch Color Blanch Ascorbic Acid (60°C for 20 min) (to 85°C) % Control (C) n i l n i l n i l Ascorbic (A) n i l n i l 0.05 Texture Blanch (T) + n i l n i l T-A + n i l 0.05 Color Blanch (Col) n i l + n i l Col-A n i l + 0.05 T-Col + + n i l T-Col-A + + 0.05 - 22 -4°C. A flowchart of this processing procedure i s shown i n Figure I I I . At 2 and 4 weeks the products were analyzed f or sensory a t t r i b u t e s , and color and texture by instrumental methods. In addition, pH, t o t a l a c i d i t y , soluble s o l i d s , drained weight, and microbiological analyses were ca r r i e d out at these times . B) Blanch Determinations As outlined i n the preceding portion, the apples, peaches, and cherries studied a l l had blanch treatments i n each t r i a l . A lso i n the cherry section of this project an additional blanch designed to improve texture was used i n processing the f r u i t . In the f i r s t apple t r i a l (Gd-I) , the apple s l i c e s were blanched to center temperatures of 65° and 85°C v i n steam and 80°C i n b o i l i n g water. The heating times for these s l i c e s were determined by i n s e r t i n g a copper-constantan thermocouple i n t o the s l i c e and securing the thermocouple t i p i n place by winding the wire around the s l i c e . The wire was then connected to a potentiometer and the s l i c e heated. The m i l l i v o l t readings obtained i n t h i s way were then converted to temperature. Eight runs were carried out using t h i s method i n both steam and b o i l i n g water. The average time to heat the s l i c e s to the required temperature was then determined. A l l other t r i a l blanches involved heating the f r u i t to d i f f e r e n t blanch temperatures after the f r u i t had been sealed i n r e t o r t pouches. To determine blanch times a copper-constantan thermocouple was inserted i n t o the center of a f r u i t section and placed i n the center of the pouch. The pouch was then f i l l e d with 200 g of f r u i t and 28 ml of water. The thermocouple lead was then passed through a packing gland and the pouch sealed. The lead was then - 23 -Figure I I I . Flowchart of Cherry Processing Plan (La-I and Mo-I) Cold Storage 'Texture' Blanch (optional) 60°C for 20 mins Cold Water Wash t P i t t i n g Packing i n Pouches with (0.05% Sorbate 0.026% Calcium 0.05% Ascorbic acid (optional) 8% Sucrose) 'Color' Blanch (optional) at 85 C Storage at 4°C - 24 -connected to a recorder which recorded the m i l l i v o l t signal or the corres-ponding temperature readings. The pouch was then heated by b o i l i n g water or steam. Eight runs were ca r r i e d out with each f r u i t c u l t i v a r . From the information gathered, average heating times were determined to heat the center of the f r u i t sections to the required blanch temperatures. One other heating process was used i n the cherry t r i a l s . A 'texture' blanch was c a r r i e d out by heating the cherries i n a 60°C water bath for 20 minutes while monitoring the center temperature with, a thermocouple f i x e d into the center of a cherry. Eight such thermocouples were set up and time-temperature data recorded during immersion of the cherries i n 60°C water for 20 minutes . C) Chemical Analyses 1) pH determination The pH of a l l the f r u i t products was monitored during each t e s t i n g period of each t r i a l . In a d d i t i o n , the pH of a pureed sample of the raw f r u i t and treatments was measured at the s t a r t of each t r i a l . Measurements were ca r r i e d out on the pureed contents of one pouch per treatment, t r i a l and time period. 2) Total a c i d i t y Total a c i d i t y of a l l three f r u i t s was determined from an extract of the pureed contents of one pouch sampled at the same rate as outlined above i n the pH det'ermination. The method of Ruck (51) i n v o l v i n g t i t r a t i n g a water extract to a pH of 8.1 with 0.10N NaOH(aq) was used. Results were expressed as a percentage of malic a c i d . 3) Soluble s o l i d s Soluble s o l i d s were measured from a pureed sample of one pouch using Ruck's method (51). As i n the case of pH and t o t a l a c i d i t y this value was - 25 -monitored i n each f r u i t at a l l storage times, and i n a l l package types and treatments . 4) G a s - l i q u i d chromatography G a s - l i q u i d chromatography (GLC) was used to investigate the formation of benyaldehyde i n the Rh-I and Fh-I peach t r i a l s . Sample pouches of raw, c o n t r o l , and flavor treatments of both c u l t i v a r s were frozen at the time of processing and after three months of storage. These 6 samples were stored at -35°C u n t i l analyzed for benaldehyde formation. A peach puree was prepared by blending 300 grams of f r u i t and 300 ml of d i s t i l l e d water. This sample was then placed i n the sample f l a s k of the c o - d i s t i l l a t i o n apparatus (see Figure IV) and slowly heated to b o i l i n g . Simultaneously, a solvent f l a s k containing 125 ml of d i s t i l l e d i n glass ethyl ether was connected to the ' s t i l l ' and heated to b o i l i n g . Both the ether and sample vapor phases were condensed (by -8°C glycerol) i n the condensing section of the d i s t i l l a t i o n apparatus. After c o - d i s t i l l a t i o n for 2 hours, the ether was dehydrated by Na2S0^ and Na2C0^ and concentrated to 0.5 ml. The samples were then stored at -5°C in 10 ml hypodermic v i a l s u n t i l analysis. The concentrate was analyzed by a Tracor MT-220 GLC using a 12' x 1/8" glass column packed with 5% carbowax 20M by weight on Anachrome 90. Nitrogen at 35 ml/min was used as a c a r r i e r gas. A flame i o n i z a t i o n detector (at 225°C) was used with a hydrogen-oxygen flame. Duplicate 5 y l samples were in j e c t e d ( i n j e c t o r at 235°C) and the oven programmed for a 60° to 200°C r i s e at 8C°/min. The temperature was then held constant for the duration of the run (25 minutes t o t a l ) . The detector signal was analyzed by a Hewlett-Packard 3390 A Integrator. Benzaldehyde was t e n t a t i v e l y i d e n t i f i e d by c o i n j e c t i o n with the sample concentrate. - 26 _ Figure IV. Diagram of C o - D i s t i l l a t i o n Apparatus (from J . Agric. Food Chem., Vol, 25, No. 1, 1977) (19) Copyright 1977 American Chemical Society - 27 -D) Physical Methods 1) The Magness-Taylor pressure test The Magness-Taylor pressure tester is commonly used as an index of f r u i t maturity (8). In t h i s project raw apples and peaches were pressure tested using a 7. 9 mm diameter, s l i g h t l y rounded probe forced i n t o the parenchyma of the f r u i t after the s k i n had been removed at the test s i t e . The maximum force recorded, or y i e l d point, was taken as a maturity index. Both portable and Instron versions (Model 1122) of the t e s t were used. The Instron version of t h i s test was the same as that of Christenson's (9). 2) Single blade shear With the exception of the Gd-I t r i a l the texture of the apple and peach s l i c e s were mechanically assessed by shearing apples and peaches i n a single blade shear c e l l from an A l i o Kramer Shear Press as described by Christenson (9). These apple and peach s l i c e s were placed 5 aside with the core or p i t edge up i n the shear c e l l . The blade was lowered at 5 cm/minute and the peak force measured from the r e s u l t i n g force-deformation curve. The tests were run i n t r i p l i c a t e taking care to select samples of uniform s i z e . This technique was used to measure f r u i t using the Instron 1122 Universal Testing Machine and the Ottawa Texture Measuring System (OTMS) (60). In the case of the Gd-I t r i a l , texture was measured using an OTMS c e l l during extrusion through a 40 x 40 cm wire g r i d . A 50 g sample was placed i n the c e l l core edge up and the ram lowered at 5 cm/minute. As with the other apple and peach analysis the peak-force was recorded. 3) Cherry texture measurement Cherry texture was determined by use of an Ottawa Texture C e l l . The peak 2 force was measured during extrusion through a plate with 1 cm diameter - 28 -holes. In a 40 x 40 an c e l l 40 grams of drained sample were placed and the c e l l ram lowered at 5 cm/minute. Peak force was taken from force-deform at ion curves and the runs were ca r r i e d out i n t r i p l i c a t e . 4) Color With the exception of the Gd-I t r i a l the color of a l l the f r u i t was measured with a Model D-25 Hunterlab Color Difference Meter. The meter was standardized using white, gold and pink ceramic standards for apples, peaches and cherries r e s p e c t i v e l y . Samples were removed from t h e i r pouches and put i n a clear plexiglass container which was placed over the aperture, covered and t h e i r L, a, and b values obtained. The sample was then rotated 90° and remeasured to obtain duplicate readings for each pouch measured . With the Gd-I t r i a l a pureed sample of equal weights of apple and d i s t i l l e d water was blended and the color measured within 60 seconds using the above procedure. 5) Drained weight Drained weight was measured by the A s s o c i a t i o n of O f f i c i a l A n a l y t i c a l Chemists (AOAC) method 22.005 (3). The contents of one pouch was measured per t r i a l , f r u i t , package type and treatment. E) M i c r o b i o l o g i c a l Analysis A l l samples were plated to determine the extent of microbial growth. One ml samples were pour plated on YEPD media (2% dextrose, 2% peptone, 1% yeast extract, and 2 % agar) (17) and stored at 4° and 37°C i n both aerobic and anaerobic conditions. Samples were taken by i n s e r t i n g a syringe i n t o the bottom of the pouch (swabbed with 70% EtOH) and t r a n s f e r r i n g 4 ml of syrup to 4 s t e r i l e p e t r i plates. To these plates, YEPD agar was added and the plates were stored i n the four conditions outlined above. The t o t a l plate count was - 29 -recorded a f t e r 48 hours and 7 days for the plates stored at 37 u and 4"C r e s p e c t i v e l y . F) Sensory Analysis Two samples from each f r u i t , time, treatment package and c u l t i v a r combin-ation were used f or sensory analyses. Each combination was tasted by 10 panelists with previous sensory analysis experience. The panelists were asked to analyze each f r u i t for odor, color, texture, taste and o v e r a l l a c c e p t a b i l i t y q u a l i t i e s . In each sensory session, up to 5 samples, i d e n t i f i e d by a 3 d i g i t code, were presented to the panelists. The portions presented included both f r u i t and syrup. Water and non-salted crackers were provided for c l e a r i n g of the palate between samples. Each panel was conducted i n taste panel booths under white fluorescent l i g h t i n g . The sensory evaluation method used was a form of Qualitative Descriptive Analysis described by Larmond (29). A continuous scale c o n s i s t i n g of a 10 cm li n e anchored at 2 and 8 cm with reference terms was used for each a t t r i b u t e and sample tested (refer to Appendix). Each judge was asked to slash on the scale at a point that best r e f l e c t e d the magnitude of the a t t r i b u t e tested. Anchor terms used i n the paneling were determined after reference to work by Yee (67) and Potter (46). The evaluations were then converted to a 0-100 score by measuring the slash l o c a t i o n i n r e l a t i o n to the l i n e length. These scores were then subjected to computer analyses. G) S t a t i s t i c a l Analyses A l l data from t e x t u r a l , c o l o r , sensory, and GLC analyses were analyzed using the University Amdahl Computer. Data from each of these q u a l i t y - 30 -att r i b u t e s from each t r i a l were submitted to either the UBC MFAV (32) or the UBC BMD-10V (6) l i b r a r y programs. These programs c a r r i e d out an analysis of variance procedure employing a Duncan's test of differences between ranked means. In addition, an attempt was made to correlate sensory a t t r i b u t e values and color and textural data using the UBC TRP l i b r a r y program (31). - 31 -RESULTS AND DISCUSSION A) Blanch T r i a l s As mentioned previously, blanch time determinations were undertaken prior to processing. Table VI displays the blanching conditions used i n each t r i a l . In the f i r s t t r i a l (Gd-I) , apple s l i c e s were blanched i n steam and b o i l i n g water. In a l l other t r i a l s the f r u i t was blanched after packaging to prevent microbial contamination, reduce oxygen contact with the raw f r u i t t i s s u e , and to reduce possible loss of aroma compounds. Based on the author's observations, these considerations outweigh the advantage of rapid heating gained by blanching the f r u i t p r i o r to processing. One problem observed i n the l a s t 9 t r i a l s was that the pouches expanded during heating creating an air pocket which caused uneven heating. Because of t h i s , i t should be noted that the heating times given i n Table IV are e s t i -mates of the time to heat the average f r u i t section's center to the blanch temperature and not a measure of the time required to heat the pouch 'cold spot' to the required temperature. In the Gd-I t r i a l , 80°C was selected as a 'blanch temperature' based on the information that apple PPO i s completely i n a c t i v a t e d after 9 seconds" at 82°C (11). The 65°C blanch treatment was selected to determine whether a milder heat treatment would be e f f e c t i v e i n improving flavor and texture while maintaining color s t a b i l i t y . The r e s u l t s of this f i r s t t r i a l (Gd-I) indicated that, although both 80°C stem and water blanch treatments were acceptable', the 65°C treatment r e s u l t e d i n s l i c e s with a d i s t i n c t region of browning. Thus, i n subsequent apple t r i a l s the e f f e c t of blanching at 80°C vs. no blanching treatment was - 32 -Table VI. Blanching Conditions f o r Each F r u i t T r i a l T r i a l Bl anching Conditions* Center Temperature,°C Time to Reach Center Temperature, sec. Gd-I S+ 65,80 30,60 Gd-I B+ 80 60 Gd-II, Gd-III, Sp-I B 80 450 Fh-I S 55,65,75 180,255,390 Fo-I S 55, 65 , 75 180,255,390 Fh-II, Rh-I B 70 315 La-I S 85 600 Mo-I S 85 600 *where S = steam heated, B = b o i l i n g water + indicates heating of product before packaging. In a l l other t r i a l s , the f r u i t was heated after packaging - 33 -examined. The r e s u l t s of these t r i a l s are discussed i n part C of t h i s s e c t i o n . Peach t r i a l s Fh-I and Fo-I examined the e f f e c t of blanch temperatures: 55, 65 and 75°C. These temperatures were selected with reference to Van Blaricom (58) to study the influence of blanch temperature on almond flavor development. In the l a t e r t r i a l s , 70°C was selected, based on the r e s u l t s of t r i a l s Fh-I and Fo-I. Almond flavor development and the r e s u l t s of the peach t r i a l s are presented and discussed i n part D of this section. The cherry blanch temperatures were decided upon after examining the results of Benjamin and Montgomery (5) and Segal et a l . (53). The 85°C blanch temperature reduced browning when compared to controls, and this e f f e c t i s discussed further i n part E. A 'texture' blanch i n t r i a l s La-I and Mo-I was also used i n an attempt to improve cherry texture. The cherries were heated to 60°C for 20 minutes i n an attempt to increase PE a c t i v i t y (59). Unfortunately, t h i s method was not e f f e c t i v e i n reducing f l u i d loss from the t i s s u e . A more extensive discussion of these r e s u l t s can be found i n part E. B) E f f e c t of Package Type In the f i r s t apple t r i a l , three d i f f e r e n t packaging-storage combinations were examined by using aluminum f o i l containing pouches and transparent p l a s t i c pouches stored i n l i g h t , and transparent pouches stored i n the dark. As discussed previously, the Gd-I t r i a l monitored the effects of time and blanch treatment on apple s l i c e q u a l i t y . When considering the effects of d i f f e r e n t package and storage conditions, i t would be expected that the difference i n package oxygen permeability and the presence or absence of v i s i b l e l i g h t would influence f r u i t color. The - 34 -Hunterlab Rd values were used as a measure of darkening because of t h e i r c o r r e l a t i o n with enzymatic browning color change (43) . The Gd-I Rd measure-ments gave s i g n i f i c a n t (P<0.01) i n t e r a c t i o n s for each combination of t r e a t -ment, time and package type. These interactions provide d i f f i c u l t y i n i n t e r p r e t a t i o n of the data, but from v i s u a l examination, i t was found that the transparent pouches did not preserve color adequately. This may be due to the greater oxygen permeability of the transparent pouches which would presumably lead to more extensive browning. In addition to the problems with color d e t e r i o r a t i o n , the transparent pouches were i n f e r i o r from a micob r i o l o g i c a l point of view. Although not reported here, the product i n transparent pouches spoiled more quickly than product i n f o i l containing pouches, due to gas production at room temperature and a f t e r extended 4°C storage. Further experiments using the transparent pouches were undertaken during the Mo-I, La-I cherry and Fh-I and Fo-I peach t r i a l s . These experiments resulted i n excessive color degradation and microbial spoilage before the 3 month term of the t r i a l s . Due to the f a i l u r e of the transparent pouches to preserve the f r u i t tested, a l l further t r i a l s i n i t i a t e d a f t e r September of 1979 (see Table I) used the aluminum f o i l laminated pouch. C) Apple Studies The apple t r i a l s Gd-I, Gd-II, and Gd-III were undertaken using Golden Delicious apples from the crop years of 1978, 1979 and 1980 r e s p e c t i v e l y . In addition, the Spartan c u l t i v a r was used i n the 1980 apple t r i a l s ( S p - l ) . After each t r i a l , r e s u l t s were examined and the experimental design for the next crop year was planned. Because of the nature of this project, the - 35 -re s u l t s of the apple t r i a l s w i l l be presented and discussed i n three sections i n the order i n which they were undertaken. In general, the apples produced from the 1979 and 1980 crop were a l l of acceptable q u a l i t y and were judged to be of better q u a l i t y than canned or frozen apples. 1) Gd-I t r i a l The Gd-I t r i a l was the f i r s t of a series of t r i a l s undertaken i n t h i s project and had a threefold purpose; to give the researcher experience i n processing and t e s t i n g f r u i t , to develop and assess methods s u i t a b l e for use i n further research and to examine the effects of heating time, package-storage conditions and storage time on the q u a l i t y parameters of apple s l i c e s . Data gathered from this and a l l of the rest of the t r i a l s can be divided into two areas for discussion; general a n a l y t i c a l r e s u l t s , and sensory and instrument evaluation. The a n a l y t i c a l results from the f i r s t t r i a l were pH, soluble s o l i d s , t o t a l a c i d i t y , microbiological s t a b i l i t y and, i n the case of raw products, Magness-Taylor values. L i t t l e change was observed with these a n a l y t i c a l results i n each t r i a l except for differences due to i n i t i a l processing. Table VII displays the a n a l y t i c a l values of raw and processed product after 10 weeks. The apples used i n t h i s f i r s t t r i a l were not of optimum qu a l i t y as they had been i n cold storage for 8 months. Their moderate qu a l i t y i s r e f l e c t e d i n t h e i r low t o t a l a c i d i t y (0.18%) and Magness-Taylor scores of 4.6 kg. Although the e f f e c t of transparent pouches on apple color and texture were measured by Hunterlab and OTMS procedures, only products i n aluminum f o i l -containing pouches were used for sensory a n a l y s i s . The sensory panel form shown i n the Appendix was used and scores from each of the f i v e a t t r i b u t e s were examined by means of a Two-way Analysis of Variance using the - 36 -Table VII. A n a l y t i c a l Values of Raw and Processed Gd-I Apple S l i c e s Product pH Soluble T o t a l Magness-Taylor M i c r o b i a l So l i d s , % A c i d i t y * * For ce, kg Count*** Raw* 4. 38 13. 2 0.18 4.6 N/A Processed* 3.65 12.0 0. 32 N/A <1 colony/ml *n = 4, **expressed as % malic acid, * * * r e s u l ts of aerobic count on YEPD media at 4°C U n i v e r s i t y ' s MFAV program (32). The r e s u l t s of this analysis show that panelists distinguished between either treatments or times for the q u a l i t y attributes of color, odor, taste and texture. The l a s t q u a l i t y a t t r i b u t e examined, o v e r a l l a c c e p t a b i l i t y , d i d not vary s i g n i f i c a n t l y with regard to either treatment or time of storage. Sensory analysis of apple color revealed a s i g n i f i c a n t difference with respect to treatment (P<0.05) and time (P<0.01). No s i g n i f i c a n t i n t e r a c t i o n was noted. Pooled means of color sensory scores arranged by treatments and times are shown i n Table VIII. The control and 60 second b o i l i n g water blanch treatments had the best color, while the steam blanched treatments were judged to have the most brown color. The 30 second steam blanch treatment which received the lowest scores contained a d i s c e r n i b l e browning r i n g within the tissue. The change i n brown color over time as measured by sensory analysis i s unusual in that i t 'peaks' at four weeks and declines over the next 6 weeks of storage. Although this phenomenon may be due to some reducing or de c o l o r i z i n g power of the adjunct mix, i t i s probably due to v a r i a b i l i t y i n panel scores . Odor scores, as measured by sensory a n a l y s i s , showed a s i g n i f i c a n t difference (P<0.01) between treatments (with no s i g n i f i c a n t time or i n t e r a c t i o n d i f f e r e n c e s ) . A Duncan's test showed s i g n i f i c a n t differences (P<0.05) between the control score (58) and the 30 second steam, 60 second steam and 60 second water blanches which had treatment mean scores of 41, 37 and 39, r e s p e c t i v e l y . An analysis of variance of the taste scores showed that s i g n i f i c a n t (P<0.05) differences occurred between treatments, times and i n treatment-time i n t e r a c t i o n s . Examination of the i n d i v i d u a l means showed no o v e r a l l trends Table VIII. Pooled Means of Sensory Color Scores of Gd-I Apple S l i c e s Treatment Sensory Score (0-100 scale) Control 30 sec. steam 60 sec. steam 60 sec. b o i l i n g water 69 a*,** 34 b 47 c 66 a Time 2 weeks 4 weeks 10 weeks 50 e*** 62 f 49 e *Mean values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's test, **n = 30, ***n = 40, (compared by treatment and time separ ately) other than a decline i n taste scores from 2 to 10 weeks. A number of panelists commented that the s l i c e s were bland t a s t i n g . Sensory texture evaluations did not d i f f e r s i g n i f i c a n t l y with regard to treatment. Presumably, since the texture of the apples before processing was so poor, the panelists were unable to discern textural differences between treatments. Also, OTMS data, when examined by an analysis of variance, showed no s i g n i f i c a n t difference with respect to treatment. Sensory and OTMS values did show s i g n i f i c a n t changes with time (P<0.05) as shown i n Table IX. Presumably, t h i s increase i n firmness is due to pectin de-es ter i f i c a t i on and subsequent calcium i n t e r a c t i o n to form intramolecular bridges. Aftfer 4 weeks, the action of polygalacturonase may play a r o l e i n softening the f r u i t by breaking down polygalacturonic a c i d u n i t s . The l a s t q u a l i t y a t t r i b u t e assessed by the sensory panel was that of ove r a l l a c c e p t a b i l i t y . No s i g n i f i c a n t differences were found with regard to either treatments or storage time. This was not an unexpected r e s u l t i n view of the poor q u a l i t y of the apples. After reviewing the data from the f i r s t t r i a l , several decisions were made regarding future t r i a l s . F i r s t , due to excessive browning of product i n the transparent pouches, a l l future t r i a l s were ca r r i e d out with f o i l laminated pouches only. Secondly, i t was decided to use 80°C as the blanch temper-ature f o r future t r i a l s . T h i r d l y , the method of blanching was altered so that a l l future blanch treatments were ca r r i e d out after packaging i n order to aid minimizing microbial contamination, possible flavor loss and additional browning. In addition, a l l f r u i t used was of fresh q u a l i t y to improve the flavor and textural q u a l i t y experienced i n these t r i a l s . - 40 -Table IX. Gd-I Apple S l i c e OTMS and Sensory-Texture Results Time , Weeks Sensory Panel Pooled Means** (0-100 scale) OTMS Treatment Means***, kg Control 30 sec. steam 60 sec. steam 60 sec. b o i l 2 50* 4. 5c 5.0c 4.6c 3.8c 4 51 a 3. 6d 6.4d 6. 2d 4.Id 10 40 b 3. 2e 4. 9e 5.0e 5.3e *Mean values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's test, **n = 40, ***n = 3 (OTMS means compared within treatments) - 41 -Since the flavor and texture were the q u a l i t y attributes which needed the most improvement, the e f f e c t of using higher l e v e l s of calcium and c i t r i c acid was investigated. A two-way f a c t o r i a l was set up i n v o l v i n g chemical and heat treatments. In, addition, some of the adjunct l e v e l s aside from calcium and c i t r i c a c i d were alt e r e d i n an attempt to improve color and taste of the apple s l i c e s . S p e c i f i c a l l y , the sugar concentration was increased to 6% (based on product weight) and the ascorbic a c i d l e v e l s were increased to 0.1%, the maximum l e v e l allowed i n Canada (2). 2) Gd-II t r i a l In the f a l l of 1979, a second apple t r i a l using Golden Delicious apples (Gd-II) was undertaken. These apples were stored at 4°C for one month and were of good q u a l i t y as indicated by t h e i r average Magness-Taylor reading of 5.5 kg and t o t a l a c i d i t y of 0.53%. As with the f i r s t t r i a l , the a n a l y t i c a l values were monitored for the duration of the experiment and did not show much change with time. Table X shows the difference i n treatment a n a l y t i c a l values monitored. As can be seen the c i t r i c a c i d treatments had s l i g h t l y lower pH and s l i g h t l y higher t o t a l a c i d i t y values. The apples were packaged before blanching using a process previously out-l i n e d . The purpose of this t r i a l was to examine the e f f e c t of d i f f e r e n t chemical treatments and blanching treatments on apple s l i c e q u a l i t y . A two-factor experimental plan was devised for sensory evaluation while a t h i r d f a c t o r , that of storage time, was considered i n both Hunterlab color and Instron texture readings. The f i r s t q u a l i t y parameter examined was color sensory scores which revealed no s i g n i f i c a n t differences between storage time or type of treatment. However, Hunterlab L values showed s i g n i f i c a n t (P<0.05) differences between treatment, blanch and time fa c t o r s . In addition, - 42 -Table X. A n a l y t i c a l Values of Processed Gd-II Apple S l i c e s Treatment pH* T o t a l A c i d i t y * Soluble Solids*, % M i c r o b i o l o g i c a l S t a b i l i t y + , col ony/ml Control 3.4 0. 52 12. 7 <1 Cal cium 3.4 0. 53 12.6 <1 C i t r i c A c i d 3. 2 0. 67 12. 5 <1 Calcium + C i t r i c Acid 3.2 0.67 12. 6 <1 *n = 2 - means of blanched and unblanched treatments at 3 months; T o t a l A c i d i t y expressed as % malic acid; +n = 4 - pooled values of aerobic and anaerobic counts at 4 + 37°C on YEPD media - 43 -s i g n i f i c a n t i n t e r a c t i o n s occurred between treatment, blanch and time i n t e r a c t i o n s . Shown i n Table XI are the treatment means for each treatment, blanch and time combination (n = 2). I t should be noted that although the L values d i f f e r s i g n i f i c a n t l y , v i s u a l examination f a i l e d to show any detectable difference. I t should also be noted that the s l i c e s were a l l of good color and that very l i t t l e change occurred i n apple s l i c e color over time. Odor of the s l i c e s was also examined by sensory panel. The r e s u l t s of this Gd-II t r i a l d i f f e r e d s i g n i f i c a n t l y with regard to blanch treatment. The heated apple s l i c e s received a s i g n i f i c a n t l y lower score of 45 vs. a score of 53 for the unheated co n t r o l . This value of 53 compares with a score obtained by the Gd-I values of 58 for the pooled control values. An analysis of the taste scores revealed that the panelists could discern no s i g n i f i c a n t difference with respect to either treatment or blanch f a c t o r s . The taste of these s l i c e s was judged acceptable and obtained a grand mean of 49 which l i e s midway between the scale anchors of 'no apple taste or o f f -taste' and ' strong apple taste' which correspond to scores of 20 and 80 r e s p e c t i v e l y . The texture r e s u l t s of these s l i c e s , when analyzed by both panel and instrumental methods, showed s i g n i f i c a n t differences between chemical treatment (P<0.05). In addition, the Instron data showed s i g n i f i c a n t differences (P<0.05) with respect to blanch and time fa c t o r s . As might be expected, the instrumental results revealed that apple s l i c e texture decreased during storage, with pooled means of peak shear force decreasing from 1.01 kg immediately a f t e r packaging to 0.55 kg at 12 weeks. The sensory and Instron values, however, do not completely agree with regard to treatment mean as shown i n Table XII. It i s obvious that calcium and c i t r i c a c i d treatments - 44 -Table XI. Gd-II Hunterlab L Values of Each Treatment, Blanch and Time Combination Storage Time, weeks Blanch Treatment Control Calcium C i t r i c C a l c i u m - C i t r i c 0 n i l 71c* 69b 69b 70b ,c 0 80°C 70b,c 68a ,b 69b 66a 12 n i l 70b ,c 69b 68a ,b 67a 12 80 °C 68a ,b 69b 65 a 66a *Values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's Test, n = 2 (compared by treatment, blanch and time) - 45 -Table XII. Gd-II Apple S l i c e Instron and Sensory Texture Results Treatment Sensory Pooled Means** Instron Pooled Means, kg*** (0-100 scale) Control 40 a* 0. 71 e Cal cium 52 a 0.98 f C i t r i c A c i d 62 c 0. 78 e,f C a l c i u m - C i t r i c Acid 49 a ,b 0.65 e *Mean values followed by the same l e t t e r within a column do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's test, ** n = 20, *** n = 6. - 46 -rank higher than the control and c a l c i u m - c i t r i c a c i d treatments. This may be due to the firming action of calcium binding to polygalacturonic a c i d side chains i n the case of the calcium treatment or a l t e r n a t e l y , the effect of c i t r i c a c i d on the polygalacturonase enzyme. The ' intermediate 1 texture of the c a l c i u m - c i t r i c a c i d treatment may be due to c i t r i c acid chelating a v a i l a b l e calcium, preventing calcium s a l t - b r i d g i n g of polygalacturonic acid uni ts . When the sensory scores from the o v e r a l l a c c e p t a b i l i t y a t t r i b u t e was subjected to an analysis of variance i t was found that no s i g n i f i c a n t differences existed between either treatment. The Gd-II apple s l i c e s were f a r superior to the samples from the Gd-I t r i a l and had good m i c r o b i o l o g i c a l , c o l o r , f l a v o r and textural c h a r a c t e r i s t i c s . Although a l l treatments were acceptable, the unblanched calcium treated sample containing 0.05% calcium was selected as the best o v e r a l l for textural quality. 3) Gd-III and Sp-I t r i a l s Although the Gd-II t r i a l was successful, two additional t r i a l s were carried out i n the f a l l of 1980. In these t r i a l s , the effects of f l a v o r i n g agents and the s u i t a b i l i t y of the Spartan c u l t i v a r were tested. Although the Gd-II t r i a l s had shown the unblanched calcium treatment to be the best o v e r a l l , the f i r s t two treatments were blanched to ensure no microbial contamination occurred. This blanching treatment was c a r r i e d out to ensure no spoilage problems would be encountered, as this was the l a s t opportunity to carry out a t r i a l . Based on previous experience, i t was presumed that i f these treatments were acceptable, then i d e n t i c a l unblanched treatments would be of superior flavor and textural q u a l i t y . Since the microbiological and color attributes were acceptable i n the Gd-II t r i a l , the sorbic and ascorbic acid l e v e l s were maintained at 0.05% and 0.1% r e s p e c t i v e l y for the control and flavor treatments. The sugar and c i t r i c a c i d l e v e l s were lowered s l i g h t l y to 5% and 0.20%. Four treatments were set up i n these two t r i a l s ; a c o n t r o l , a flavor treatment (containing an apple e x t r a c t ) , an unheated ju i c e treatment and f i n a l l y a blanched j u i c e treatment. The f i r s t two treatments had t h e i r adjuncts dissolved i n a d i s t i l l e d water base, while the l a s t two used apple j u i c e obtained from Sun Rype Products Limited, Kelowna, as a solvent. Although i t had been planned to add the e n t i r e range of adjuncts to the juic e t r e a t -ments, i t was found that only ascorbic acid could be added to the j u i c e without detracting from i t s f l a v o r . Therefore, 0.1% ascorbic acid only, i n combination with apple j u i c e , was added to the apple s l i c e s . Table XIII shows the a n a l y t i c a l values of each treatment and c u l t i v a r at three months. The only notable difference observed i s i n the lower soluble s o l i d s and t o t a l a c i d i t y of the juic e treatments. Results from sensory color analyses showed that neither treatment nor c u l t i v a r values d i f f e r e d s i g n i f i c a n t l y . When viewing the Hunterlab L values, an analysis of variance found that treatment scores d i f f e r e d s i g n i f i c a n t l y (P<0.05). Table XIV shows the pooled treatment means. Results of a Duncan's test are also shown. I t i s i n t e r e s t i n g to note that the j u i c e treatments were of a darker color as indicated by the Hunterlab 'L' scores. Presumably, the absence of adjuncts such as calcium and c i t r i c a c i d and the presence of polyphenols would tend to increase browning of the f r u i t . When the odor scores were analyzed, the only s i g n i f i c a n t difference observed was between c u l t i v a r s where the Spartan c u l t i v a r received a s i g n i f i c a n t l y better score of 51 vs. 40 for the Golden Delicious c u l t i v a r . - 48 -Table XIII. A n a l y t i c a l Values of Processed Gd-III and Sp-I Apple S l i c e s at 3 Months Treatment Cul ti v a r pH* T o t a l * A c i d i t y , % Soluble* Sol i d s , % M i c r o b i o l o g i c a l S t a b i l i t y col ony/ml Control Golden Delicious 3.6 0. 39 12. 7 <1 Flavor Golden Delicious 3.7 0.38 12.6 <1 J u i ce-unbl anched Golden Delicious 3.5 0.32 9.5 <1 J u i ce Golden Delicious 3.6 0. 32 10.1 <1 Control Spart an 3.2 0.45 14.0 <1 Flavor Spartan 3. 2 0.42 14.0 <1 J u i c e -unbl anched Spartan 3.4 0.40 11.8 <1 J u i ce Spartan 3. 3 0.40 11.7 <1 * n = 2, Total A c i d i t y expressed as % malic a c i d + n = 4, for anaerobic and aerobic counts at 4 and 37°C on YEPD media - 49 -Table XIV. Pooled Gd-III and Sp-I Hunterlab 'L' Values at 3 Months Treatment L Value* Control 67.0 a Flavor 66. 6 a Juice-unblanched 63.8 b J u i ce-blanched 65.1 a,b *Mean values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's t e s t , n = 4. - 50 -Sensory texture data showed s i g n i f i c a n t interactions between treatments and c u l t i v a r s (P<0.05). Table XV shows the means for each c u l t i v a r and treatment. As could be expected the f i r s t two treatments containing adjuncts were judged to r e t a i n t h e i r firmness best. An analysis of variance of the Instron values showed no s i g n i f i c a n t differences between treatments or c u l t i v a r s . Upon inspection, the only obvious difference i s that between the f i r s t two and l a s t two treatments. As expected, the f i r s t two treatments had higher textural scores than the j u i c e treatments. Sensory taste evaluation revealed that panelists judged the f i r s t two treatments to be of more apple-like taste, as shown i n Table XVI. The loss i n apple taste i n the j u i c e treatments over time may be due to the fact that the apple taste compounds i n the jui c e are more e a s i l y degraded than the sugar-c i t r i c a c i d mixtures added i n the f i r s t two treatments . Overal l a c c e p t a b i l i t y scores from the Sp-I and Gd-III t r i a l s showed a s i g n i f i c a n t difference between treatments (P <0.01). These pooled means and the re s u l t s of a Duncan's test are shown i n Table XVII. With t h i s q u a l i t y parameter, as with the others such as color and texture, the panelists selected the f i r s t two treatments as being of better q u a l i t y . In summary, these Gd-III and Sp-I t r i a l s were p a r t i a l l y successful i n producing a desirable product i n both the Golden De l i c i o u s and Spartan c u l t i v a r s . Although the j u i c e treatments were of marginal acceptance, the control treatments of both c u l t i v a r s had a high q u a l i t y , s i m i l a r to the calcium treatment of the Gd-II t r i a l . The flavor treatment did not s i g n i f i c a n t l y (P>0.05) a f f e c t the taste or odor scores i n either of the c u l t i v a r s tested. - 51 -Table XV. Gd-III and Sp-I Sensory Texture Means Treatment Cul t i v a r Sensory Texture Score (0-100 scale) Control Golden Delicious 47b,c* Flavor Golden Delicious 46b, c J u i ce-unbl anched Golden Delicious 33a ,b Juice-blanched Golden Delicious 45a ,b ,c Control Spartan 40a,b ,c Flavor Spartan 51c J ui ce-u nbl an che d Spartan 33a ,b Juice-blanched Spartan 31a *Values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's test, n = 10 (compared by c u l t i v a r and treatment) - 52 -Table XVI. Gd-III and Sp-I Pooled Sensory Taste Means Treatment Pooled Sensory Taste Scores (0-100 scale) Control 51 a* Flavor 48 a Juice-unblanched 44 a Juice-blanched 32 b *Mean values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's test, n = 20. - 53 -Table XVII. Sensory O v e r a l l A c c e p t a b i l i t y Scores f or Gd-III and Sp-I T r i a l s Treatment O v e r a l l A c c e p t a b i l i t y Score (0-100 scale) Control 48 a* Flavor 52 a Juice-unblanched 46 a Juice-blanched 32 b *mean values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's test, n = 20. - 54 -4) Summary of the apple t r i a l s Of a l l of the apple t r i a l s , the l a s t two crop years (Gd-II, Gd-III and Sp-I) produced treatments of good q u a l i t y with s h e l f l i v e s of over 3 months. The q u a l i t y of these s l i c e s was thought to be superior to canned and frozen products, although no direct comparisons were made. The control treatments of the l a s t two t r i a l s , Gd-III and Sp-I, are of a q u a l i t y s u i t a b l e for market tes t i n g . Further research i n this area i s s t i l l needed as ou t l i n e d i n a further section of this t h e s i s . D) Peach Studies Peach t r i a l s were c a r r i e d out using the 1979 and 1980 crops. In 1979, both clingstone (Fortuna, Fo-I) and freestone (Fairhaven, Fh-l) c u l t i v a r s were studied, and i n the following year, two freestone c u l t i v a r s , Fairhaven (Fh-II) and Redhaven (Rh-I), were examined. As with the Gd-I apple t r i a l s , the f i r s t peach t r i a l s were pr i m a r i l y concerned with the e f f e c t of blanching on r e f r i g e r a t e d f r u i t q u a l i t y . 1) Fo-I and Fh-I t r i a l s A processing and experimental plan was set up as discussed previously, i n consultation with s t a f f of the Summerland Research Station and the information i n the l i t e r a t u r e (4,22,65,66). In the f i r s t two t r i a l s , each c u l t i v a r was given f i v e treatments as shown i n Table IV. As i n the apple t r i a l s , analyses for pH, soluble s o l i d s and t o t a l a c i d i t y were ca r r i e d out re g u l a r l y . As well, color, texture and sensory q u a l i t i e s were analyzed using the Hunterlab Color Difference Meter, Instron and sensory panel. A n a l y t i c a l r e s u l t s varied l i t t l e with treatment or storage time. However, there was a substantial difference between c u l t i v a r s . Table XVIII shows these a n a l y t i c a l values at 3 months . - 55 -Table XVIII. Fo-I and Fh-I A n a l y t i c a l Values at 3 Months C u l t i v a r pH T o t a l A c i d i t y * , % Soluble S o l i d s , % Drained Wt., % Fortuna 3.78 0.36 11.34 76 Fairhaven 3.44 0.69 11.34 68 n = 5 average of a l l 5 treatments (as the values did not d i f f e r s u b s t a n t i a l l y between treatments). *Total A c i d i t y expressed as % malic acid. - 56 -The color of the peaches was examined by both instrumental and sensory methods. Sensory evaluation, using the taste panel form shown i n the Appendix, f a i l e d to detect a s i g n i f i c a n t difference i n peach color with regard to treatment, time, or c u l t i v a r . The color of the peaches was good with no browning v i s u a l l y evident. Examination and s t a t i s t i c a l evaluation of the Hunterlab 'L' values (which ind i c a t e browning) showed s i g n i f i c a n t differences (P<0.01) with regard to treatment, time, and c u l t i v a r , as well as a number of s i g n i f i c a n t i n t e r a c t i o n s . Since there was a s i g n i f i c a n t treatment, time and c u l t i v a r i n t e r a c t i o n , a Duncan's test was ca r r i e d out on the i n d i v i d u a l c e l l means. An examination of the 3 month means i s shown along with the results of t h i s Duncan's test (P=0.05) i n Table XIX. From th i s table i t i s i n t e r e s t i n g to note that the L values are lower i n the unblanched treatment i n d i c a t i n g they browned more than the blanched treatments. I t should also be noted that the absence of calcium did not increase browning as has been reported by some researchers (9,43). An analysis of variance of the sensory odor scores revealed that only storage time had a s i g n i f i c a n t (P<0.01) difference. The sensory panels were car r i e d out at 2, 4 and 12 weeks and a Duncan's test (P<0.05) revealed that the 4 week score (43) d i f f e r e d s i g n i f i c a n t l y from the 2 and 12 week values of 52 and 51, r e s p e c t i v e l y . Reasons for t h i s observation are not known, as differences were not observed i n other related q u a l i t y attributes of taste or almond f1avor. After submitting the textural data (both Instron and sensory) to an analysis of variance, a s i g n i f i c a n t (P<0.05) i n t e r a c t i o n was found to occur between the c u l t i v a r and treatment factors for both sets of data. This i n t e r a c t i o n i s not unexpected since the difference i n texture of these f r e s h - 57 -Table XIX. Fo-I and Fh-I Hunterlab 'L 1 Values at 3 Months Treatment C u l t i v a r Fairhaven Fortuna Control 50. 7 a* 52.4 b,c No-C a l cium 50.9 a 52.1 b 55°C Blanch 53.7 d,e 53.7 d,e 65°C Blanch 53.8 d,e 53.4 c,d 75°C Blanch 54.6 e 53.3 c,d *Mean values f o l l o w e d by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's t e s t , n = 2 (compared by treatment and c u l t i v a r ) . - 58 -c u l t i v a r s i s quite large. Table XX shows that the Fairhaven c u l t i v a r responded best to a blanch of 65°C and d i f f e r e d s i g n i f i c a n t l y (P<0.05) from the unheated treatments. This indicates that the blanching may i n a c t i v a t e polygalacturonase thus preventing softening. I t i s also i n t e r e s t i n g to note that the treatment without calcium was no softer than i t s control. The Fortuna c u l t i v a r , on the other hand, gave much higher firmness readings. In f a c t , t h i s c u l t i v a r was never considered acceptable due to i t s high firmness. An analysis of variance of sensory taste data for these two t r i a l s found s i g n i f i c a n t differences between treatments (P<0.01) and treatment c u l t i v a r i n t e r a c t i o n s . In Table XXI the treatment means are shown by c u l t i v a r along with the re s u l t s of the Duncan's te s t . Although the re s u l t s are somewhat mixed i t can be seen that the blanched Fairhaven c u l t i v a r treatments are ranked better than the unblanched treatments. With a l l of the Fairhaven treatments, a s l i g h t but d i s t i n c t off flavor was noticeable. Analysis of variance of the almond flavor data revealed a s i g n i f i c a n t difference between treatments . These pooled treatment means are shown i n Table XXII. A Duncan's test indicated that the peaches given blanch treatments had the lowest almond flavor as shown by the high score value. When examining the o v e r a l l a c c e p t a b i l i t y values derived from sensory panels, i t was found that the treatment-cultivar i n t e r a c t i o n gave a s i g n i f i c a n t e f f ect (P<0.05). Table XXIII shows the treatment-cul tiv a r c e l l means along with Duncan's test r e s u l t s . The Duncan's test gave r e s u l t s rather d i f f i c u l t to i n t e r p r e t ; however, when examining the Fairhaven means there appears to be a tendency for the blanched treatments to score higher. When examining a l l the qua l i t y attributes tested i n this t r i a l i t can be concluded that the 65°C and 75°C blanch Fairhaven treatments had the best - 59 -Table XX. Fo-I and Fh-I Texture Data Results Treatment C u l t i v a r  Fairhaven Fortuna Sensory Score Single Shear Peak Sensory Single Shear Peak (0-100 s c a l e ) * * Force, kg*** Score** Force, kg*** (0-100 scale) Control 33 a* 0.86 y 71 d 8.80 z No-Calcium 36 a 0.84 y 64 d 7.6 z 55°C Blanch 42 a,b 1.20 y 69 c,d 9.6 z 65°C Blanch 46 b 1.46 y 63 c,d 10.8 z 75°C Blanch 42 b 1.28 y 59 c 0.8 z *Mean values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's t e s t , **n = 6, ***n = 30 (compared by treatment and c u l t i v a r ) . - 60 -Table XXI. Pooled Sensory Taste Fo-I and Fh-I Results Treatment C u l t i v a r Fort una Fairhaven (0-100 scale) (0-100 scale) Control 42 a,b* 42 a ,b No-Cal cium 43 a 39 a 55°C Blanch 46 a,b, 58 c 65°C Blanch 48 a ,b 51 b,c 75°C Blanch 52 b ,c 48 a ,b *Mean values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's t e s t , n = 30 (compared by treatment and c u l t i v a r ) . - 61 -Table XXII. Pooled Sensory-Almond Fo-I and Fh-I Results Treatment Almond Flavor (0-100 scale) Control 54 a* No-Calcium 56 a 55°C Blanch 66 b 65°C Blanch 67 b 75°C Blanch 63 b *Mean values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's t e s t , n = 60. - 62 -Table XXIII. Fo-I and Fh-I Sensory O v e r a l l A c c e p t a b i l i t y Results Treatment C u l t i v a r Fortuna Fairhaven (0-100 scale) (0-100 scale) Control 44 b,c* 36.5 a No-C al cium 47 c,d 42 a,b 55°c Blanch 43 b,c 52 c,d 65°C Blanch 46 b,c 52 c,d 75°C Blanch 46 d 49 c,d *Mean values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's t e s t , n = 30 (compared by treatment and c u l t i v a r ) . - 63 -o v e r a l l quality. A lso, the Fortuna samples were of unacceptable q u a l i t y due to excessively firm rubbery texture. The q u a l i t y of the two 65°C and 75°C blanch Freestone treatments was superior when compared to canned peaches, although no experimental comparisons were made. However, a s l i g h t off flavor was present which was not i d e n t i f i e d . The flavor of these two treatments needed further improvement to eliminate this u n i d e n t i f i e d o f f - f l a v o r . 2) Fh-II and Rh-I t r i a l s This second set of t r i a l s had three objectives; f i r s t to evaluate the s u i t a b i l i t y of the Redhaven c u l t i v a r f o r t h i s type of processing, second to test the effectiveness of a peach flavor concentrate i n masking the peach off flavor and t h i r d , to determine whether t h i s o f f flavor development was due to benzaldehyde formation. As the 65°C and 75°C treatments were the most acceptable i n the Fh-I t r i a l , the blanch l e v e l for t h i s second set of t r i a l s was set at 70°C. A l l other procedures and adjunct levels remained the same with the exception of the sugar and c i t r i c a c i d l e v e l s . In an attempt to give a sweeter taste to the f r u i t , the sugar l e v e l was increased to 6% and the c i t r i c a c i d l e v e l was reduced to 0.4%. The a n a l y t i c a l values monitored did not change s u b s t a n t i a l l y over time or between treatments and are shown i n Table XXIV. The sensory color data revealed s i g n i f i c a n t differences between factors and no s i g n i f i c a n t i n t e r a c t i o n s . The peaches were a l l of good color with no v i s i b l e browning at 3 months. Examination of Hunterlab 'L' values revealed a s i g n i f i c a n t i n t e r a c t i o n between c u l t i v a r s and time (P<0.05). Examination of the c u l t i v a r means at each time by a Duncan's test i s shown i n Table XXV. At 3 months the Fairhaven c u l t i v a r shows less evidence of browning as shown by the score of 54. - 64 -Table XXIV. Fh-II and Rh-I A n a l y t i c a l Values at 3 Months Cul ti v a r pH T o t a l A c i d i t y ,* 1 \ Soluble S o l i d s , % Drained Wt., % Fairhaven 3.77 0.67 12.8 67 Redhaven 3. 76 0. 64 12. 9 65 n = 4, average of 2 treatments (as the values did not d i f f e r s u b s t a n t i a l l y ) * T o t a l A c i d i t y expressed as % - 65 -Table XXV. Pooled Rh-II and Rh-I Hunterlab L Values Storage Time, C u l t i v a r weeks Redhaven Fairhaven 0 63 e* 61 d 2 56 c 52 a,b 12 52 a 54 b *Means values followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by Duncan's t e s t , n = 20 (compared by time and c u l t i v a r ) . - 66 -The odor, taste, almond flavor and o v e r a l l a c c e p t a b i l i t y q u a l i t y a t t r i b u t e s did not d i f f e r between c u l t i v a r or treatment (P>0.05). This indicates that the flavor concentrate added to each c u l t i v a r was not e f f e c t i v e i n masking the s l i g h t o f f - t a s t e which occurred after 3 months storage of these peaches. The peaches were also analyzed by GLC to discover i f the developing o f f - f l a v o r was due to benzaldehyde production. Analysis of Instron and sensory texture data was also c a r r i e d out. The sensory-texture scores d i f f e r e d s i g n i f i c a n t l y (P<0.05) between v a r i e t i e s with the Fairhaven and Redhaven having pooled means of 57 and 37, r e s p e c t i v e l y . Instron single-shear peak values showed a s i g n i f i c a n t difference (P<0.05) between c u l t i v a r as well with the Fairhaven and Redhaven having values of 1.13 and 0.97 kg, r e s p e c t i v e l y . A l l four cultivar-treatment combinations from t h i s second set of peach t r i a l s were acceptable with l i t t l e difference occurring i n q u a l i t y due to treatment. The Fairhaven c u l t i v a r was s l i g h t l y firmer; however, both c u l t i v a r s gave a product of superior q u a l i t y when compared to canned peach products. 3) GLC analysis GLC analysis was c a r r i e d out on samples from the l a s t two t r i a l s , Fh-II and Rh-I. Samples were taken of the raw and 3 month storage treatments and analyzed by GLC as described previously. A l l 6 of the samples tested gave similar chramatograms with a series of three peaks having retention times of between 9 and 12 minutes. Figure V shows a chroraatogram of the raw Fairhaven sample which is t y p i c a l of the chromatograms obtained. The t h i r d peak i n this series was t e n t a t i v e l y i d e n t i f i e d as benzaldehyde by c o i n j e c t i o n of the sample concentrate with benzaldehyde. - 67 -Figure V. A Typical Gas-Liquid Chromatogram Obtained During GLC Analysis of Peach Samples (Fh-II Raw Sample) - 68 -An analysis of variance of the integrated areas under the t h i r d , or benzaldehyde, peak showed that both c u l t i v a r s and treatments d i f f e r e d s i g n i f i c a n t l y (P<0.01). Table XXVI shows the pooled treatment means by treatment and c u l t i v a r along with the r e s u l t s of a Duncan's test f o r the pooled treatment means. It can be seen from this table that only the raw treatments, having a s i g n i f i c a n t l y higher l e v e l of benzaldehyde, d i f f e r from the processed three month samples. This f i n d i n g agrees with sensory data previously discussed which f a i l e d to detect any s i g n i f i c a n t differences between 3 month treatment means. L i t e r a t u r e reports of benzaldehyde development i n pouched r e f r i g e r a t e d peaches a l l refer to unblanched samples (22,48,65). Presumably the enzymes and pathways responsible for benzaldehyde production are destroyed during blanching. Thus, from the r e s u l t s of this analysis as shown i n Table XXVI, one could conclude that the s l i g h t o f f - f l a v o r that occurs i n the stored r e f r i g e r a t e d peach samples is not due to benzaldehyde production. Also, when examining Table XXVI i t can be seen that the Redhaven c u l t i v a r contains much more benzaldehyde than the Fairhaven c u l t i v a r . 4) Summary of peach t r i a l s In summary i t can be stated that treatments from each of the two crop years studied were of acceptable and of superior quality. Although the Fortuna c u l t i v a r was not acceptable due to excessively firm texture the 65°C and 75°C blanch treatments of the Fh-I t r i a l , and the control treatments of the Fh-II and Rh-I t r i a l s gave good quality peach s l i c e s . A s l i g h t off flavor which i s not the r e s u l t of benzaldehyde production was found to develop i n the peaches. This flavor is not unacceptable, however, i t does give the processed peaches a flavor s l i g h t l y d i f f e r e n t from fresh peaches. - 69 -Table XXVI. Results of Fh-II and Rh-I Benzaldehyde Analysis by Treatment and Cul t i var Treatment R e l a t i v e Area Under Benzaldehyde Peak Raw 14370 a* Control 12340 b Flavor 12320 b Cul t i v a r Redhaven 17360** Fairhaven 8660 *Means followed by the same l e t t e r do not d i f f e r s i g n i f i c a n t l y (P>0.05) by a Duncan's test, *n = 4, **n = 6 - 70 -E) Cherry Studies The cherry t r i a l s , Mo-I and La-I, were ca r r i e d out using the 1979 crop. Each t r i a l consisted of eight i d e n t i c a l treatments as outl i n e d i n Table V. As previously discussed, these treatments were set up to test the e f f e c t of ascorbic a c i d , a 'color' blanch and a 'texture' blanch on cherry q u a l i t y . When these t r i a l s were i n s t i t u t e d i t was planned to examine the product qu a l i t y at 2, 4 and 12 weeks. However, microbial and textural problems caused the c a n c e l l a t i o n of these two t r i a l s at 4 weeks. When the cherries were examined at 12 weeks, the control treatments had noticeable o f f - f l a v o r s due to spoilage. M i c r o b i a l examination was s t i l l c a r r i e d out at 12 weeks and the re s u l t s of t h i s monitoring can be seen i n Table XXVII. The controls of each t r i a l and the texture treatments of the Lambert cherries showed signs of spoilage. Table XXVIII contains the mean a n a l y t i c a l values for each c u l t i v a r calculated from the pooled treatment means. Since the pH of the f r u i t was r e l a t i v e l y low, the amount of spoilage i s somewhat unexpected. This high incidence of contamination may be due to a high i n i t i a l load which i n turn might occur due to the p i t t i n g operation. Texture, the other major quality problem, was r e f l e c t e d i n excessive f l u i d loss caused by the p i t t i n g operation. Also, the texture data from both t r i a l s ( i . e . sensory and OTMS values) showed no s i g n i f i c a n t difference due to treatment e f f e c t s . As well, no substantial differences were observed i n the drained weights between treatments. These data do not agree with the reports of Van Buren (59) and LaBelle and Moyer (26) who recommend a heat treatment or blanch to improve texture. - 71 -Other quality parameters such as color, odor, taste and o v e r a l l accept-a b i l i t y , i n general, d i d not d i f f e r s i g n i f i c a n t l y due to treatment. Also, any s i g n i f i c a n t effects occurring may be due to microbial contamination rather than 'true' treatment e f f e c t s . Thus, i n summary, the r e s u l t s of both these cherry t r i a l s are disappointing due to microbial contamination and poor textural q u a l i t y from the p i t t i n g operation. Suggestions for further research to improve cherry q u a l i t y are discussed i n a l a t e r s ection of t h i s t h e s i s . - 72 -Table XXVII. Mo-I and La-I M i c r o b i o l o g i c a l Results at 3 Months* Treatment Anaerobic Aerobic 4°C 37°C 4°C 37°C Mo-I La-I Mo-I La-I Mo-I La-I Mo-I La-I Control (C) 10 TNTC** 40 50 75 TNTC 100 TNTC Control Ascorbate (C-A) TNTC TNTC 10 150 37 TNTC 105 TNTC Texture Blanch (T) 1 TNTC 0 40 0 100 0 100 T-A 0 100 10 40 0 100 0 40 Color Blanch (Col) 0 0 0 0 0 0 0 1 Col-A 0 0 0 0 0 0 0 0 T-Col 2 0 0 0 0 0 0 0 T-Col-A 5 0 0 0 0 0 0 0 *n = 1, expressed as colonies/g **TNTC = Too Numerous To Count - 73 -Table XXVIII. Mo-I and La-I Pooled A n a l y t i c a l Values. Cul t i v a r pH T o t a l A c i d i t y , * % Soluble S o l i d s , % Drained Wt., % Montmor ency 3.50 0.93 13.7 65 Lambert 3.80 0.48 19.5 70 *Total A c i d i t y as % malic a c i d - 74 -CONCLUSIONS The o b j e c t i v e of t h i s study was to examine the f e a s i b i l i t y of producing prepared, r e f r i g e r a t e d apple, peach and cherry products of good q u a l i t y with minimum s h e l f l i v e s of three months. Although research devoted t o producing a r e f r i g e r a t e d cherry product was h a l t e d a f t e r one season, good q u a l i t y r e f r i g e r a t e d apple and peach products were produced. From t h i s study, a number of conclusions can be drawn. Some of these have been p r e v i o u s l y mentioned since conclusions from the e a r l y t r i a l s determined the experimental design of l a t e r t r i a l s . I n reviewing these points i t i s perhaps best to present them as they are p a r t i t i o n e d i n the Results and D i s c u s s i o n s e c t i o n of t h i s t h e s i s . Thus, conclusions concerning blanching and package type are d e a l t with f i r s t , f o l l o w e d by conclusions concerning apples, peaches and c h e r r i e s . A) Blanching Studies The purpose i n blanching the f r u i t s was t h r e e f o l d ; to reduce the chance of m i c r o b i a l s p o i l a g e , to r e t a r d browning and t o l e s s e n t e x t u r a l degradation. I n the case of peaches, bl a n c h i n g was a l s o used t o prevent undesirable f l a v o r development. I n examining the r e s u l t s of the apple t r i a l s , some general conclusions can be drawn. The most important outcome of the Gd-I t r i a l was the observation that a 30 second blanch, that r a i s e d the apple s l i c e center temperature to 65°C, caused a n o t i c e a b l e browning r i n g which i n d i c a t e d an inadequate thermal treatment. I n the Gd-II t r i a l , where ' d u p l i c a t e ' (heated vs. unheated) treatments were undertaken, the only q u a l i t y parameter s e r i o u s l y - 75 -affected by heat was the odor of the apples as determined by sensory evaluation. It was found that blanching the apples gave a s l i g h t l y lower score than for those apples which were not blanched. Examination of the Gd-III and Sp-I t r i a l s , demonstrated that blanching became an important preserving method i n the absence of chemical preservatives. However, i t i s preferable to use processing adjuncts to obtain the best apple s l i c e q u ality. The f i r s t freestone peach t r i a l s (Fh-I) showed that blanched peaches had better color, texture, taste, odor and o v e r a l l a c c e p t a b i l i t y than the unblanched f r u i t . Almond flavor was also reduced i n the heated samples. Although i n most cases the 55°, 65° and 75°C blanch treatments did not d i f f e r s i g n i f i c a n t l y , optimum values for the quality parameters tended to l i e i n the 65 to 75°C range. In the Fh-II and Rh-I t r i a l s , a l l f r u i t s were blanched and thus comparisons of heated vs. unheated treatments were not c a r r i e d out. I t i s i n t e r e s t i n g to note that GLG analysis of benzaldehyde indicates that benzaldehyde does not increase i n blanched peaches upon r e f r i g e r a t e d storage. Since microbial spoilage occurred i n some of the cherry treatments, only two li m i t e d conclusions can be drawn. F i r s t , a blanch to an inside center temperature of 80°C gives good color and microbial protection and second, th i s treatment coupled with the p i t t i n g operation r e s u l t s i n excessive and unacceptable f l u i d loss from the t i s s u e . B) Packaging Studies One of the o r i g i n a l intents of this study was to examine the f e a s i b i l i t y of using d i f f e r e n t f l e x i b l e package types of varying gas and l i g h t perme-a b i l i t y . However, i t was soon determined that only the aluminum f o i l - 76 -containing laminated pouch gave products of acceptable q u a l i t y a f t e r three months of storage. With a l l three f r u i t s tested, i t was found that unacceptable levels of browning and microbial spoilage occurred i n the transparent pouches. As the preservation of f r u i t i n a near fresh form i s a d i f f i c u l t task, i t was conclued that an oxygen and l i g h t impermeable container i s a n ecessity. C) Apple Studies The apple t r i a l s were ca r r i e d out with f r u i t from three crop years using the Golden Delicious c u l t i v a r i n 1978 and 1979 and both the Spartan and Golden Delicious c u l t i v a r s i n 1980. Both the 1979 (Gd-II) and 1980 (Gd-III and Sp-l) crop years gave good qu a l i t y apple s l i c e s . The f i r s t t r i a l (Gd-I) measured the e f f e c t of blanch treatment on apple s l i c e q u a l i t y . When examining a l l of the quality parameters i t was found that the 60 second water blanch gave the best texture and color values. Based on these r e s u l t s , a second (Gd-II) t r i a l was undertaken which measured the effect of blanching, c i t r i c a c i d and calcium l e v e l s on apple s l i c e q u a l i t y . From th i s t r i a l , extensive data were compiled. S t a t i s t i c a l analysis showed that no s i g n i f i c a n t differences (P>0.05) existed between treatments with regard to a l l the quality parameters measured, except sensory odor, sensory texture and Instron texture values. Unblanched s l i c e s gave the best sensory odor r e s u l t s . This i s not unexpected as blanching i s known to a f f e c t f r u i t f l a v o r . In addition, the calcium treatments resulted i n the best preservation of apple s l i c e texture. In the t h i r d set of t r i a l s the use of an additional c u l t i v a r , a 'flavor extract' treatment and a 'juice' flavored treatment were c a r r i e d out. These - 77 -two t r i a l s produced excellent quality products i n the case of both the Golden Delicious and Spartan control treatments. 'Flavor-extract' treatments did not d i f f e r s i g n i f i c a n t l y from the controls (P>0.05). Also, the blanched and unblanched ju i c e treatments gave poor q u a l i t y products. D) Peach Studies Peaches, the second major f r u i t tested, gave a successful product i n both the 1979 and 1980 crop years. In the f i r s t year, both freestone and c l i n g -stone peaches were examined. The Fortuna peaches were generally unacceptable due to t h e i r extremely firm texture. The blanch treatments of the Fairhaven peaches gave good r e s u l t s with both the 65 and 75°C treatments being of good quality. In the second peach t r i a l s , both the Fairhaven and Redhaven c u l t i v a r s were examined. The addition of a flavor extract proved i n e f f e c t i v e i n improving sensory taste scores. However, both c u l t i v a r s were judged to be of good q u a l i t y . In addition, the Fairhaven c u l t i v a r proved to be firmer than the Redhaven c u l t i v a r after 3 months. E) Cherry Studies Cherries were the l a s t f r u i t examined for s u i t a b i l i t y as a r e f r i g e r a t e d product. Both sweet (Lambert) and sour (Montmorency) cherries were used. The r e s u l t s of these t r i a l s were disappointing. In both t r i a l s , microbial contam-i n a t i o n occurred, making observation of other attributes d i f f i c u l t . In addition, excessive f l u i d loss occurred due to the p i t t i n g operation. F) Summary In summary, the most important conclusion that can be gained from t h i s t hesis i s that production of high quality r e f r i g e r a t e d apple and peach s l i c e s i s possible with B r i t i s h Columbia c u l t i v a r s . Golden Delicious and Spartan apples and Fairhaven and Redhaven peaches have been shown to give acceptable q u a l i t y products after storage of up to three months. - 79 -SUGGESTIONS FOR FURTHER RESEARCH This section was included i n t h i s thesis as an aid to planning further research i n t h i s f i e l d . Due to the nature of this research i t was necessary to i n i t i a t e a large number of experiments at the time of f r u i t ripening. A three month storage time was then needed before these experiments could be evaluated. Then a further nine months were needed before new experiments could begin on f r e s h f r u i t . Thus, research i n t h i s area i s very time consuming. It i s hoped that the following suggestions might reduce any future researchers' time spent on 'non-productive' experiments. The prime objective of any future research on r e f r i g e r a t e d apple s l i c e s should be to examine the s u i t a b i l i t y of other apple c u l t i v a r s to t h i s process. A second d i r e c t i o n for i n v e s t i g a t i o n of apple products would be to examine flavor make up and changes i n storage. Hopefully, a more r e f i n e d method of adding apple f l a v o r to the apple products could be developed. The main thrust of any research on r e f r i g e r a t e d peach s l i c e s should be to i d e n t i f y m ild flavors occurring due to processing and storage. Once i d e n t i f i e d , a method of re t a r d i n g t h i s flavor development should be found. Much research remains to be c a r r i e d out before a s u i t a b l e cherry product is developed. The two main quality problems are microbial spoilage and excessive f l u i d loss from the t i s s u e . Possibly, the storage of unpitted cherries might solve these two problems. However, the loss of consumer convenience and the possible ' p i t f l a v o r ' occurrence are two possible draw-backs to this process. - 80 -F i n a l l y , the a p p l i c a t i o n of t h i s process to other B r i t i s h Columbia f r u i t s should be investigated. 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U n i v e r s i t y of B r i t i s h Columbia, Department of Food Science, Vancouver, B.C. - 86 -APPENDIX A) Sensory Panel Forms 1) Processed apple s l i c e s Date Panelist Please evaluate the samples for color, texture, odor, taste and o v e r a l l a c c e p t a b i l i t y by placing a slash on the l i n e at an appropriate p o s i t i o n . COLOR Brownish Pale Sample # Yellow Yellow Comments: ODOR No Apple Odor Strong Sample # or Off-Odor Apple Odor Comments: - 87 -TEXTURE Sample # Soft Firm l — L Comments; TASTE Comments: _L No Apple Taste Strong Sample # or o f f taste Apple Taste _L OVERALL ACCEPTABILITY Sample # Not acceptable Very Acceptable Comments: - 88 -2) Processed peach s l i c e s Date Panelist Please evaluate the samples for color, texture, odor, taste, almond fl a v o r , and o v e r a l l a c c e p t a b i l i t y by placing a slash on the li n e at an appropriate p o s i t i o n . COLOR Brownish Yellow Sample # or Uneven Color Yellow Comments: ODOR No Peach Odor Strong Sample # or Off-Odor Peach Odor Comments: - 89 -TEXTURE Sample # Soft Firm I _L J — L Comments: TASTE No Peach Taste Strong Sample # or Off-Taste Peach Taste Comments: ALMOND FLAVOR Sample # Strong Disagreeable No Almond Almond Flavor Flavor Comments: - 90 -OVERALL ACCEPTABILITY Sample # Not Acceptable Very Acceptable Comments: - 91 -Processed cherries Date Panelist Please evaluate the samples for color, texture, odor, taste and o v e r a l l a c c e p t a b i l i t y by placing a slash on the l i n e at an appropriate position. COLOR Faint Red Sample # or Brown Red I i Comments: ODOR No Cherry Odor Strong Sample # or Off-Odor Cherry Odor Comments: - 92 -TEXTURE Sample # Soft Firm I — Comments: TASTE Comments: J L No Cherry Taste Strong Sample # or Off-Taste Cherry Taste OVERALL ACCEPTABILITY Sample # Not Acceptable Very Acceptable Comments: 

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