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Studies on the rehydration of irradiated freeze-dried beef Ni, Yeng-Wei 1969

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STUDIES ON THE REHYDRATION OF IRRADIATED  FREEZE-DRIED BEEF  by YENG-WEI NI B.Sc,  Chung-Hsing U n i v e r s i t y , 1967  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of FOOD  SCIENCE  We accept t h i s t h e s i s as conforming required  t o the  standard  THE UNIVERSITY OF BRITISH COLUMBIA August, 1969.  In p r e s e n t i n g an the  thesis  advanced degree at Library  I further for  this  shall  the  in p a r t i a l  fulfilment of  University  of  make i t f r e e l y  agree tha  permission  s c h o l a r l y p u r p o s e s may  by  his  of  this  written  representatives.  be  available  granted  gain  permission.  of  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, C a n a d a  for  for extensive by  the  It i s understood  thesis for financial  Department  British  Columbia  shall  requirements  Columbia,  Head o f my  be  I agree  r e f e r e n c e and copying of  that  not  the  that  study.  this  thesis  Department  copying or  for  or  publication  allowed without  my  A B S T R A C T The t o t a l water uptake, r a t e o f water uptake, e x t r a c t r e l e a s e volume and maximum shear f o r c e were measured on a s e r i e s o f samples o f i r r a d i a t e d f r e e z e - d r i e d beef. F o r t y seven p i e c e s o f round steak (2.5 cm x 2.5 cm x 10.4  cm  o r 1" x 1" x 4") were i r r a d i a t e d a t one, t h r e e and f i v e megarad.  The c o n t r o l samples were not i r r a d i a t e d .  H a l f o f the  samples were i r r a d i a t e d when f r e s h , and the other h a l f were i r r a d i a t e d a f t e r freeze drying.  T h i s procedure has been  d e f i n e d as the " f r e s h - d r y " i r r a d i a t i o n sequence throughout the r e p o r t .  The samples were f r o z e n i n an a i r b l a s t a t two  temperatures  (-22.2°C and -56.1°C).  Freeze-drying  was  c a r r i e d out below 300 microns o f Hg and a maximum s h e l f temperature o f 15.6°C (60°F). There appears t o be t h r e e phases o f water uptake: 1)  A very r a p i d , almost i n s t a n t a n e o u s , a b s o r p t i o n .  2)  A more gradual uptake ( c a l l e d Part.1 i n the r e p o r t ) .  3)  A r e l a t i v e l y slow asymptotic approach t o an e q u i l i b r i u m condition  (Part 2).  These two l a s t phases are shown t o be s t r a i g h t l i n e s when the l o g a r i t h m o f the water uptake i s p l o t t e d a g a i n s t the l o g a r i t h m of the immersion time. I r r a d i a t i o n l e v e l has no s i g n i f i c a n t e f f e c t on the f i n a l water content o r on the slow asymptotic a b s o r p t i o n (Part 2) o r the e x t r a c t r e l e a s e volume, but has a s i g n i f i c a n t e f f e c t on the g r a d u a l water uptake (Part 1) and on the shear press  force.  Fresh-dry i r r a d i a t i o n sequence (and freezing rate) have a s i g n i f i c a n t effect on the t o t a l water uptake and on the slow asymptotic water (Part 2) uptake, but not on the gradual water uptake (Part 1), or on the extract release volume or on the shear press forces. Freezing rates have a s i g n i f i c a n t effect on the t o t a l water uptake, but not on the slow asymptotic water uptake (Part 2), on the gradual water uptake (Part 1), on the extract release volume or on the shear press forces. The highest t o t a l water uptake was found f o r the meat i r r a d i a t e d when fresh, and slow frozen at -2 2.2°C. The mechanism of the gradual absorption appears to follow a phenomena of water flow, as evidenced by the straight l i n e relationship found in the plots of logarithm water uptake versus logarthm immersion time.  TABLE OF CONTENTS  Page  Introduction  1  Review of Literature •  2  Experimental methods (1)  13  Preparation of Samples  13  (a) Procurement of samples  13  (b) Size of sample  13  (2.) Freezing and freeze-drying  13  (3)  Irradiation  15  (4)  Rehydration  16  (5)  Extract release volume  16  (6)  Shear press measurements  17  (7) Analytical methods Results  17 18  Moisture content  18  Rehydration  18  Extract release volume  20  Shear press  20  Discussion of Results Moisture content  20  Rehydration  21'  Total water uptake  21  Rehydration rate analysis  24  Page  Extract-release volume  29  Shear press  32  Conclusions  35  List of References  37  Appendix A  42  Appendix B  46  Appendix C  .  6  1  LIST OF TABLES  Table  Page  1  Experimental design  14  2  Moisture Content of fresh beef  18  3  Very rapid i n i t i a l water uptake (% D.B.) for irradiated freeze dried beef  19  Analysis of variance of the f i n a l water uptake of freeze-dried beef: Effect of fresh-dry irradiation sequences, irradiation levels, and freezing rate  22  Mean total water uptake (% D.B.) of freezedried beef irradiated fresh and irradiated after freeze-dried  23  6  Mean total water uptake (% D.B.) of freezedried beef frozen at different temperatures  23  7  Analysis of variance of the slopes of the regression lines of log (moisture) vs. Log (time) as shown i n Appendix B  27  Comparison of the slope of the regression lines for part 1 of the rehydration process as influenced by irradiation levels  28  Comparison of the slope of the regression lines (part 2) as influenced by fresh-dry irradiation sequence  28  Analysis of variance of extract-release volume of reconstituted freeze-dried beef: Effect of irradiation levels, fresh-dry irradiation sequence, and freezing rate  30  Mean extract-release volume (average of 6 samples) as influenced by irradiation level and fresh-dry sequence  31  Analysis of variance of Kramer Shear press force for rehydrated freeze-dried beef: Effect of irradiation levels, fresh-dry irradiation sequence and freezing rate  33  4  5  8  9  10  11  12  Page Mean Kramer shear force values for rehydrated freeze-dried beef irradiated at four dose levels  33  Mean Kramer shear press force values for rehydrated freeze-dried beef subjected to two fresh-dry irradiation sequences and freezing rates 34 Water loss during freeze-drying and final water content of the freeze-dried beef for animal no. 6868 (group A)  43  Water loss during freeze-drying and final water content of the freeze-dried beef for animal no. 6852 (group B)  44  Water loss during freeze-drying and final water content of the freeze-dried beef , for animal no. 6852 (group C) ~  45  Analysis of part 1 regression lines for rehydration of freeze-dried beef  59  Analysis of part 2 regression lines for rehydration of freeze-dried beef  60  Extract-release volume of the rehydrated beef samples  62  Shear press value of the rehydrated beef samples  63  LIST OF FIGURES FIGURE 1  2  PAGE Recorder used i n the r e h y d r a t i o n process showing weight gains ( a b s c i s s a ) with time ( o r d i n a t e ) .  16a  Equipment used f o r the r e h y d r a t i o n process.  16a  3  Model o f c a p i l l a r y flow.  24  4 5  Rehydration model. Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 1, 2, 3 and 4 r e p r e s e n t s sample IA, 2A, 3A and 4A r e s p e c t i v e l y .  25  47  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 5, 6, 7 and 8 r e p r e s e n t s sample 5A, 6A, 7A and 8A r e s p e c t i v e l y .  48  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 9, 10, 11 and 12 r e p r e s e n t s sample 9A, 10A,'11A and 12A r e s p e c t i v e l y .  49  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 13, 14, 15 and 16 r e p r e s e n t s sample 13A, 14A, 15A and 16A r e s p e c t i v e l y .  50  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 17, 18, 19 and 20 r e p r e s e n t s sample IB, 2B, 3B and 4B r e s p e c t i v e l y .  51  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 21, 22, 23 and 24 r e p r e s e n t s sample 5B, 6B, 7B and 8B r e s p e c t i v e l y .  52  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 25, 26, 27 and 28 r e p r e s e n t s sample 9B, 10B, 11B and 12B r e s p e c t i v e l y .  53  6  7  8  9  10  11  FIGURE 12  13  14  15  16  PAGE Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 29, 30, 31 and 32 r e p r e s e n t s sample 13B, 14B, 15B and 16B r e s p e c t i v e l y .  54  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 33, 34, 35 and 36 r e p r e s e n t s sample 2C, 3C, 4C and 9C r e s p e c t i v e l y .  55  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 37, 38, 39 and 40 r e p r e s e n t s sample 10C, 11C, 12C and 5C r e s p e c t i v e l y .  56  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 41, 42, 43, and 44 r e p r e s e n t s sample 6C, 7C, 8C and 13C r e s p e c t i v e l y .  57  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 45, 46 and 47 r e p r e s e n t s sample 14C, 15C and 16C r e s p e c t i v e l y .  58  ACMOWLFJJGMENTS  The writer wishes to express his appreciation for assistance in this study by:  Professor E. L. Watson, Department of Agricultural Mechanics and Agricultural Engineering, who directed this research, provided encouragement, advice and guidance with patience. Dr. J . F. Richards, Department of Food Science, for counsel on the research project, and for arranging for the provision of beef samples and laboratory f a c i l i t i e s . Mr. M. A. Tung, for suggestions and assistance i n the use of the I.B.M. 360 computer and provision of computer programmes. Mr. W. Gleave and Mr. E. Nyborg, for suggestions and assistance i n the construction of the strain gauge transducers.  0  INTRODUCTION  Rehydration of freeze-dried beef has been studied for some time (1,20), but the process has had limited application i n practical fields.  The reason has been that the properties of beef rehydration  are such that i t does not reconstitute to i t s original state. The problem remains that once the beef i s frozen and freeze-dried, i t has lost i t s f u l l water holding capacity and rehydration to i t s original colour, tenderness and other constituents i s d i f f i c u l t . It i s generally accepted that rehydration behavior of dried products i s important in .determining value.  their organoleptic and nutritional  Prolonged rehydration may cause a loss of water soluble constituents  such as pigments, carbohydrates and amino acids.  The extent of recons-  titution i s considered to affect the texture of rehydrated  products.  The purpose of this thesis i s to study four different irradiation levels, "fresh/dry" irradiation sequences and two freezing rates to see how these various procedures affect the water uptake, rehydration rate, shear resistance and water holding capacity of irradiated freeze-dried beef. The results of such experiments would be helpful in advancing the understanding of the process of rehydration of meat and i n improving the acceptability of freeze-dried meat.  2 REVIEW OF THE LITERATURE General Problems on Rehydration Auerback et a l . (1)  proposed that the ability to rehydrate  rapidly i s one of the most distinctive qualities of freeze-dried products and i s a factor that demonstrates the superiority of freezedrying over other methods of dehydration.  In order to obtain a satis-  factory product, Auerback et a l . found the direction of muscle fiber and angle of cut to be quite important.  Smithies  (30) mentioned that  unsatisfactory processing conditions or prolonged storage may affect the rehydration time, tenderness and juiciness of the products. Smithies also reported that the protein denaturation or migration of soluble solids or fat which takes place makes the structure less hydrophilic and increases the time required for the water to penetrate the porous structure; he found that relatively rapid freezing gives a product which rehydrates more slowly than does slow freezing. Auerback et a l . (1) reported that the mechanism of rehydration of freeze-dried muscle involves two stages: f i r s t l y , the penetration of water through the cavities i n the tissues, (either the large ones formed between the fibers i n slow freezing or the minute ones formed within the fibers in rapid freezing); secondly, the penetration of water through the muscle fibers of the tissue. The porosity of the muscle fibres i s related to the rate at which the tissue i s frozen and also to the storage temperature conditions.  Auerback also stated that:  3  "In both the slowly and the rapidly frozen tissues, water would appear to penetrate more freely through the muscle fibers than through the cavities.  With rehydration the time necessary for total or nearly  total water intake and water holding capacity has to be considered. Quick rehydration i s often combined with relatively low water holding capacity.  This i s caused on the one hand by the growth of large ice  crystals during slow freezing which results i n relatively large holes i n the dry product through which water can permeate the dry product quickly. On the other hand during the slow freezing procedure the material may suffer relatively substantial structural and biochemical changes which result i n decreased water holding capacity". (1) Properties of Beef Koshland and Herr (18). reported that muscle proteins are responsible for the binding of water i n meat.  The muscle proteins  consist of water-soluble protein and non-water-soluble proteins.  The  water insoluble muscle protein represents the structural substance i n meat. They found that the f i b r i l l a r proteins consist of myosin, which shows a specific interaction with water.  Huxley and Hanson (13) re-  ported that the f i b r i l l a r proteins also consist of actin, X-protein, and stroma proteins. Ham (9) thought that changes of the water holding capacity of meat may mainly concern actin and myosin"or the complex actomyosin. Fujimaki and Nakajima (8) believe that globular proteins also have some influence on water holding capacity, and i t appears that meats containing a greater quantity of globular protein have a greater water holding capacity.  4  Hamm (9) also found that the low-molecular weight water-soluble compounds contribute considerably to meat hydration.  This effect may be caused mainly  by inorganic ions because low molecular weight compounds can be substituted by NaCl solution, which has the same ionic strength as muscle juice.(9). •  Olcott and Fraenkel-Conrat (26) found that the activity of  proteins for binding water i s diridnished by blocking polar groups with certain reagents, and proved in that manner that polar groups are responsible for the water binding.  According to Pauling (27) the i n i t i a l  phase of binding of water by protein consists of the binding of one water molecule by one polar group. different polar groups varies. most active groups  The a f f i n i t y for water of the  Therefore water attaches f i r s t to the  and then to the less active.  According to Nemethy and Scherage (24) the characteristic configuration and reactivity of proteins are governed to a large extent by covalent disulfide bonds and by noncovalent interactions between side chains. Hydrophobic bonds, or the tendency for nonpolar groups to 0  associate i n an aquepus environment are thought to be of considerable importance in stabilizing protein structure.  This view can be readily  justified by considering the anrino acid composition of typical proteins. In general, the amino acids with nonpolar side chains constitute 35-50% of the total amino acids in proteins (24,25).  Since the nonpolar side  chains have a low a f f i n i t y for water, they tend to approach one another u n t i l they are within their Van der Waals r a d i i and thereby irrinimize their contact with water.  «  5  The structure of the water molecule enables i t to form weak but directed bonds with other water molecules and with certain groupings on the principal macromolecules present, i n foodstuffs. The hydrogen atom has a special function, stemming from the absence of inner shells of electrons i n the formation of this type of secondary bond, which justifies the use of the term 'hydrogen bond' for a l l interactions of a similar character.  In most foodstuffs hydrogen  bonding exists between water molecules, between water and small and large molecules and ions and as a cross link between ions of macromolecular components. Water appears to be bound i n several ways i n most biological materials.  Use of the term "bound water" often leads to a great deal  of confusion since no one definition has been universally accepted. As the water present i s always "bound" i n some way to one or other of i t s components, this i s a complex matter and depends on many different factors. Kuprianoff 0.5,.) pointed out two d i f f i c u l t i e s i n the def i n i t i o n of "bound water" - the water w i l l be bound to protein i n a manner different from that to carbohydrates or acids, i t w i l l be advisable to consider the problem of "bound water" with special reference to different foods or groups of foods of similar structure and composition, e.g. fish and meat. The second d i f f i c u l t y arises because the definition of "bound water" i s based on the method used for i t s determination, and every individual method has i t s own efficiency or capacity of expelling water.  6  Bull (.2) presents probably the two most common ways of defining bound water: 1)  Bound water can be defined i n terms of the water which  remains unfrozen at some prescribed temperature below 0°C. The temperature usually chosen i s -20°C, although Luyet (19) defines bound water as "water which does not crystallize at any temperature". 2)  Bound water can be defined i n terms of the amount of  water i n the system which i s unavailable as a solvent. A general definition of bound water has been given by Kupriaroff (15) as "that part of the water content of a product which remains i n i t in an unchanged (or bound) state after application of the usual drying procedures, such as freezing, chemical'dehydration, etc., and which can be expelled only by heating to 100°C-110°C for a sufficiently long time". Irradiation Ionizing radiation can destroy spoilage microorganisms regardless of the state of the meat, that i s , whether raw or cooked, frozen or unfrozen.  Some effects other than the destruction of spoilage  microorganisms do occur.  These include: 1) Color changes - the red  pigments of raw meats and poultry become brownish. Cooked meats and poultry i n the absence of oxygen turn pink.  The magnitude of the color  changes i s somewhat dependent on the dose (32): 2) Texture - a softening of the lean tissue can occur, the degree of this effect being related to the dose (3) • 3) an odour and/or flavour change may occur.  This  7  most important organeleptic change, generally regarded as undesirable, i s characteristic and resembles scorching.  Within limits, the amount  or irradiation-flavour development i s dependent on the dose (32). Whitehair et a l . (33) reported that within a species, i t appears that the flavour or odour sensitivity i s not related to the fat content of the tissue. Because of the high percentage of water in meats and other foodstuffs the reactions that occur when water i s irradiated are of primary importance.  By radiolysis of water, H , OH , t h ^ , and H^ +  are the f i n a l major products, but free radicals are formed along the path of the primary electron and react with each other as diffusion occurs.  Also some of the products formed along the track move about  and react with solute molecules. In order to examine how the meat i s affected by irradiation, Weeks and Garrison (34-) studied the influence of irradiation on pure protein i n solution. These authors proposed that the major products formed by the irradiation of glycine i n solution are NH^, CHOCOOH, Yi^, and C0 . 2  Doty (5) stated that other amino acids show similar reactions, although the influence of certain side groups w i l l change the overall reaction products.  Fujimaki et a l . (7) also reported that aromatic  amino acids, especially phenyl-alanine, tend to be sensitive to irradiation, and the ring structure w i l l be altered.  Free arginine,  tyrosine, and methionine are also destroyed to a greater extent than other amino acids.  8  In the case of cysteine, Doty (5) proposed that the -SH group i s so efficient in trapping free radicals that the rest of the molecule i s almost completely protected from attack, and cystine i s the major product formed.  In addition, some H S 2  i s formed and oxidation  reactions may produce other products as well. Hedin et a l . (12) reported that there i s a general decrease in the unchanged amino acids, with almost total loss of methionine and cysteine and 25 percent loss of histidine.  Fox et a l . (6) reported that other chemical changes occurring  when meat i s irradiated cause modifications in the myoglobin of red meats and some destruction of the vitamins present.  When red meats are  irradiated at dosages of 1.5 megarad, or higher, appreciable quantities of metmyoglobin are produced.  In low acid food, such as uncured meats,  the radiation dose required for sterilization i s about 4-.5 megerad (35).  For bacon i t i s 2.0 or 2.5 megarad.  For chicken, i t i s about  3.5-4.0 megarad (28). Sparrman et a l . (29) reported that minimum irradiation damage to Agrestic stolonifera seed occurred at 15% moisture content. Wedemeyer and Dollar (36) reported that the sulfhydryl release resulting from irradiation reaching a maximum at about 20% moisture content for sole f i l l e t s . There i s very l i t t l e specific information on texture changes during irradiation of meats.  But i t i s generally agreed that, after  irradiation, meats become softer and more tender.  For example, Kirn  et al.(16) noted that raw beef given 2 megarad retained a good texture even after 5 years at 7°C.  Coleby et a l . (4) noted considerable  immediate softening accompanied by loss of fluid with both raw beef and  9  pork.  Lawrie et a l . (21) found on examination of the raw tissue  no evidence of breakdown of connective tissue after 5 Megarad irradiation. Bailey et a l . (3) reported that the treatment of pork or beef with ionizing radiation resulted i n a tenderization, as judged by a taste panel after cooking, detectable at a dose of 2 megarad and marked at 4megarad. Freezing Process In principle the rate of freezing may be conveniently expressed as the time spent between i n i t i a l ice crystal formation and complete solidification.  Two principal freezing rates were considered by Luyet  (19): one i n which the material stays at the freezing temperature about one hour; the other i n which i t stays there about 10 min.  The two  corresponding modes of freezing w i l l be designated, hereafter, respectively, as slow and rapid freezing.  The outstanding characteristics of  freeze-dried material which had been frozen slowly i s i t s relatively course, spongy structure.  Freeze dried tissues which had been frozen  rapidly have a fine porous structure. Kuprianoff (17) found when the temperature i s decreased below the freezing point of a food, the crystallization of ice within the water phase begins when nucleation occurs.  Having i n mind that most  biological tissues supercool, the nucleation process w i l l start at a lower temperature than the freezing point, depending on the type of solution and i t s inclination for supercooling. In reality specific freezing point of food does not exist; what we c a l l "freezing point" i s the equilibrium temperature at the beginning of ice formation; i n the weak unsaturated solution pure ice i s formed, which i s i n  10 equilibrium with the remaining more concentrated solution; the freezing point of the remaining solution has been depressed because of i t s increased concentration. At some particular concentration the remaining solution w i l l freeze as a whole, forming mixed crystals of solute and solvent at i t s eutectic point. In biological tissues with given structure the water phase i s . contained i n single and complex systems (cells) separated from each other by c e l l wall and membranes; i n an intact tissue these c e l l walls and membranes - being semipermeable - are able not only to maintain different concentrations of the same substances i n the solutions i n neighbour c e l l s , but also to hinder the crystallization of water (slowing down the rate of heat transfer) slowing down the rate of ice formation and influencing the speed of growth of the ice crystals.  Under practical  conditions of temperature drop during the freezing of foods crystallization usually starts i n the intracellular connective tissues and proceeds with some delay i n the interior of the cells (15) An important consequence for food freezing i s the increase i n water volume during ice formation, which amounts to about 10% when ice i s formed at 0°C.  Therefore, the c e l l structure of most foods  w i l l be exposed to mechanical forces during the freezing process. Kuprianoff (15) proposed that although the tissues of foodstuffs are exposed to a considerable strain by the expansion of water during freezing, in most cases the foodstuff w i l l have sufficient elasticity to ininimize disruption, i f the product, i s frozen rapidly.  The muscles  of a l l warmblooded and of some coldblooded animals have especially good  11  resistance against deformation.  Their elasticity and ^constitution  a b i l i t y are remarkably good, when tested immediately after freezing and subsequent thawing.  I f larger crystals are formed - by slow freezing -  or i f the strength of the c e l l structure i s low, then the fine structure of tissue may be disrupted and w i l l partially collapse; this kind of freezing injury leads to the loss i n natural strength of tissues, to permeability of c e l l walls, to partial loss of water holding capacity and to impairment of the food texture.  After thawing of the product  the permeability of the tissue results i n a drip and i n loss of texture, giving a soft product.  This leads to a decrease in organoleptic^ '  acceptability due to lack of juiciness and increase i n toughness. Freeze-drying process The process of freeze-drying i s based on the principle that the water of an aqueous system can be separated from a nonvolatile component by freezing and removal of the ice by sublimation, leaving a dry substrate. Meryman et a l . (23) proposed that the process of freeze-drying of a frozen speciman can be divided into three steps: of heat to supply the energy necessary for sublimation,  1) the introduction 2) the transfer  of water vapor from the subliming ice crystal through the already dried shell of the speciman, and the specimen surface.  3) the removal of water vapor that reaches  Harper and Tappel (10) pointed out that sub-  limation always takes place from the ice surface.  As sublimation progresses  the ice phase recedes and becomes surrounded by a dried layer. The heat for sublimation must be transferred through this dried layer, and water  12  vapor must flow out through the same layer.  Throughout most of the  drying process, this dried layer resists both the inward transfer of heat and the outward transfer of water vapor.  Harper et a l . (11)  found that the drying process involves a balance between the outward flow of vapor (mass transfer) and the inward flow of heat (heat transfer). Vapor movement from the ice phase takes place by hyobxdynamic flow as a result of a gradient i n water vapor pressure.  It should be noted  that the partial pressure of water vapor can never rise above the equilibrium vapor pressure of the ice i n the frozen material.  13 EXPERIMENTAL METHODS  (1) Preparation of samples (a) Procurement of samples A l l the samples for the experiment were obtained from the Agricultural Research Station, Agassiz, B.C.  The samples  were as follows: Beef Animal No. 6868  5th Round  Beef Animal No. 6852  4th Round  Beef Animal No. 6852  5th Round  Beef Animal No. 6852  6th Round  (b) Size of sample The fresh meat samples were cut into even sizes of 2.5 x 2.5  cm  cm x 10.2 cm (1" x 1" x 4"), each weighing approximately  75 grams, and were subjected to freezing and then freeze-drying. After the freeze-drying, the samples were trimmed to 1.9 cm x 1.9 cm x,7.6 cm (3/4" x 3/4" x 3") sizes, each weighing approximately 8.50 grams. The experiment i s a factorial experiment, with three independent variables:  Irradiation levels, (4 levels) "fresh/dry" irradiation (2  sequences), and freezing rate (2 rates) which are 4 x 2 x 2 = 16 factors. The experimental design i s shown i n Table 1. (2) Freezing and Freeze-drying The freezing operation was carried out at two different temperatures, -22.2 °C (-8°F) and -56.1 °C (-69°F).  Two pairs Cu-Constantan  thermocouples were used to indicate the temperatures' at the surface and the center of the sample and to detect the end points when the temperature  TABLE 1 EXPERTJ1EOTAL DESIGN  Irradiation Levels  &  CD  5 Mrad  Irradiated while fresh  OJ  3 Mrad  1A* IB  IC  Irradiated while dry  M H  1 Mrad  9A  9B  9C 10A 10B IOC 11A 11B 11C 12A 12B 12C  Irradiated while fresh  -22.2'2°C (-8°F)  Freezing temperature I  0 Mrad  5A  5B  5C  2A  6A  2B  6B  2C  6C  3A  7A  3B  7B  3C  7C  MA  8A  MB  8B  MC  8C  to  (0  •P  M  •S N CU QJ  £  O °H iH ID  T3 •H X) CU S H £ 'H  13A 13B 13C IMA 1MB IMC 15A 15B 15C 16A 16B 16C  •? £ • §  sample identification symbol A  Animal No. 6868  B and C Animal No. 6852  15 at the centre equals the surface temperature.  Temperatures were recorded  by a Moseley recorder. It took 10.25 minutes for the temperature at the centre of the sample to pass through 0°F when frozen at -56.1 °C (-69°F) and 125 minutes when frozen at -22.2. °C (-8°F).  In order to prevent water loss  from the samples during theofreezing process, the samples were kept i n plastic bags. A l l the samples were freeze-dried i n a Thermovac Model FDC-10-DR freeze-dryer.  In this freeze-dryer, heat was supplied by an electric  heating system inside the shelves, maintained at 15.6°C (60°F) and the absolute pressure was maintained at values less than 300 microns of Hg by a positive displacement vacuum pump and a condenser at -56.1°C (-60°F). (3)  Irradiation A Gamma Cell 220 Irradiator with a Cobalt-60 source was used  in this study. The dose rate was 1.1 Mrad per hour.  The irradiation  was carried out on both fresh and freeze-dried meat samples.  Three g  different irradiation dosages, 1, 3 and 5 megarads (1 Megarad = 10 Rad , 1 Rad = 100 ergs/giJ for the experiment were used.  In order to  prevent damage to the sample due to heat during the irradiation operation, a l l the samples were kept at an ambient temperature of 0°C by surrounding the  samples with ice cubes. One half of the fresh meat samples were f i r s t subjected to  irradiation and then were frozen at -22.2 °C (-8°F) or -56.1 °C (-69°F), and freeze-dried.  The other half of the samples were f i r s t freeze-dried  and then irradiated.  This procedure i s designated as "fresh/dry"  irradiation sequence throughout this report.  16  (4) Rehydration The samples were rehydrated by immersing i n a water bath at room temperature (22°C) and atmospheric pressure. The sample was kept completely immersed i n water at room temperature with i t s muscle tissue perpendicular to the surface of water, until a straight line was recorded on the recorder chart indicating no more gain i n weight (Figure 1). The gain i n weight due to absorption of water i n the sample was measured by a cantilever type strain gauge transducer.  The sample was attached to one end of the cantilever  beam. The gain i n weight was recorded by a Moseley recorder connected to the strain gauge transducer (Figure 2). The cantilever beam strain gauge transducer was calibrated by applying a series at known loads and recording the resulting bridge .output. The transducer was found to have linear output characteristics. Hence, no calibration curve i s presented.  Strain gauges were mounted so  that the transducer was temperature compensated. (5) Extract release volume The method used by Jay (14) was followed to measure the Extract Release Volume (ERV).  ERV was determined by weighing  25 grams  of rehydrated meat and homogenizing for 2 minutes with 100 ml of d i s t i l l e d water added just prior to blending. The homogenates were poured directly into the funnels, equipped with a sheet of filter paper. The extract was collected i n 100 ml graduated cylinders. The collection was timed for 15 minutes from the point of adding the homogenates to the funnel.  The 15-minute volumes were averaged and treated as the  Extract Release Volume.  FIGURE 1.  RECORDER USED IN REHYDRATION PROCESS, SHOWING WEIGHT GAIN (ABSCISSA) WITH TIME (ORDINATE).  FIGURE 2 .  EQUIPMENT USED FOR THE REHYDRATION PROCESS.  17  (6)  Shear Press measurements The shear press results were obtained with an Allo-.lramer  Shear Press, Model TP-2 Texture-press and TR-1 Texturecorder.  A l l the  samples (1.9 cm or 3/4" thick) were placed i n a single blade Kramer c e l l for each test.  A downstroke of 30 seconds and a 2500 l b ring were used.  Results were recorded as pounds force as measured at the peak of the shear value. (7) Analytical Methods The experiment was treated as a factorial experiment, the methods of analysis of variance, F-ratio tests, and simple linear regression were used as stated by LeClerg et a l . (22) and by Steele and Torrie (31).  RESULTS  Moisture Content TABLE 2 MOISTURE CONTENT OF FRESH BEEF  Animal No. 6868  Animal No. 6852  Moisture Content  Moisture Content  Dry Basis %  Wet Basis %  1  305.26  75.32  1  306.28  75.39  2  297.22  74.83  2  288.92  74.29  3  310.60  75.65  3  315.21  75.92  4  293.22  74.57  4  298.53  74.91  5  303.26  75.20  5  299.47  74.97  6  296.32  74.77  6  307.13 '  75.44  7  274.83  73.32  7  284.78  74.01  8  283.67  73.94  8  297.99  74.87  Mean  292.17  74.70  Mean  299.74  74.98  Dry Basis %  Wet Basis %  The moisture content of the fresh beef i s shown i n Table 2. The weights of the fresh samples of the freeze-dried samples, and the water losses during freeze-drying as percent dry basis (% D.B.), and the moisture content of the freeze-dried samples % W.B.  and % D.B.  as percent wet basis,  are presented i n Appendix A.  Rehydration The very rapid i n i t i a l water uptake i s reported i n Table 3. The rest of the rehydration data are shown graphically i n Appendix B.  19 TABLE 3 VERY RAPID INITIAL WATER UPTAKE (% D.B.) FOR IRRADIATED FREEZE DRIED BEEF  Sample Water uptake Dry matter wt. No.  Sample No.  Water uptake ^00 Dry matter wt. x  Sample Water uptake D.M. wt. No.  x  -  IA  182.57  IB  119.13  IC  2A  126.14  2B  87.58  2C  114.92  3A  71.19  3B  107.49  3C  58.39  4A  53.05  4B  70.36  4C  57.45  5A  110.21  5B  131.62  5C  145.37  6A  .118.46  6B  74.04  6C  110.28  7A  33.88  7B  62.06  7C  .146.81  8A  41.44  8B  84.97  8C  116.30  9A  51.52  9B  117.49  9C  137.96  10A  7.40  10B  23.14  10C  85.57  1LA  31.07  11B  55.21.  11C  90.74  12A  35.14  12B  39.94  12C  109.95  13A  19.15  13B  131.65  13C  161.77  14A  3.80  14B  36.06  14C  108.42  15A  51.43  15B  36.31  15C  122.77  16A  17.90  16B  28.83  16C  111.04  • *  100  20  The analysis of variance of the total f i n a l water uptake i s given i n Table 4. Table 5 and Table 6 show the mean final water uptake (% D.B.) as influenced by "fresh-dry" irradiation sequence and freezing rate respectively.  The rates of rehydration are shown i n Appendix B as  a series of graphs showing the logarithm of water uptake versus the logarithm of immersion time.  The regression analysis of the logarithm  of water uptake versus logarithm time i s given i n Appendix B. The analysis of variance of the slope of the regression lines i s presented i n Table 7. Extract-Release Volume The Extract-Release Volume (ERV) results are shown i n Appendix C. The analysis of variance of of ERV i s given i n Table 10 and Table 11. Shear Press The Kramer shear force data are shown  inAppendix  C. The  analysis of variance of shear press data of the rehydrated freeze-dried beef i s given i n Table 12. A comparison of mean values of shear force found for the rehydrated beef treated with four levels of irradiation i s presented i n Table 13. The combined effect of freezing rate and "fresh-dry" irradiation sequence on mean shear press values are shown i n Table 14. DISCUSSION OF RESULTS Moisture Content The moisture content of the fresh beef samples appeared to be normal (Table 2). The water losses during freeze-drying were somewhat variable (Appendix A).  The water loss during freeze-drying of certain  samples (i.e. Group A, No, 2,3; Group B, No. 7), does not f a l l within  21  the range of moisture contents found for fresh beef.  Presumably these  samples must have had i n i t i a l moisture contents outside the range which was. found for fresh beef.  The moisture contents of the freeze-dried  samples (see Appendix A) were also quite variable.  This may be due to  different i n i t i a l moisture contents and/or different freeze-drying regimes. Rehydration There are two rehydration characteristics of freeze-dried products. Most workers have studied the total amount of water absorbed. In these studies the rate of water absorption was also measured.  It was  noted that some water was absorbed very rapidly (almost instantaneously) in a l l samples.  However the amount of water absorbed varied greatly  between samples (Table 3). Total water uptake It i s shown i n Table 4 that there was no significant difference for the different levels of irradiation on the final water uptake. However, according to Fujimaki et a l . (7) irradiation of meats produces some damage to the protein, but i n this study protein damage to meat was not investigated and i t i s therefore impossible to say whether or not the rehydration was mainly due to the absorption of water by protein. A highly significant difference i n water uptake between the samples irradiated when fresh and when freeze-dried was found by the analysis of variance (Table 4). The samples which were irradiated i n the fresh state were found to reabsorb more water (Table 5). The fact that the samples irradiated after freeze-drying regained less water than the samples irradiated i n the fresh state would indicate that greater damage  22 TABLE 4 ANALYSIS OF VARIANCE OF THE FINAL WATER UPTAKE OF FREEZE-DRIED BEEF: EFFECT OF FRESH-DRY IRRADIATION SEQUENCES, IRRADIATION LEVELS, AND FREEZING RATE  Source  DF  Irradiation levels (A)  Sum Sq  Mean Sq  Prob  F  3  3677.4  1225.8  1.68  0.1902  Fresh-dry irradiation sequence (B) 1  5812.2  5812.2  7.96**  0.0080  Freezing rate (C)  1  4904.0  4904.0  6.71*  0.0137  AB  3  2035.4  678.48  0.92  0.4399  AC  3  2485.8  828.61  1.13  0.3505  BC  1  611.4  611.40  0.84  0.3704  ABC  3  3631.7  1.66  0.1947  Error .  32  . 23379.0  Total  47  46537.0  1210.6 730.59  significant at 95% level significant at 99% level occurred under the extremely low moisture condition. However, this does not agree with Wedemeyer and Dollar (36) who reported that the least irradiation damage of f i s h occurred at low mristure content.  This would  indicate that their measure of irradiation damage (-SH production) does . not measure irradiation damage to rehydration. The analysis of variance (Table 4) shows that the freezing temperature has significant effect on the f i n a l amount of water absorbed.  23  The difference (Table 6) i n the water holding capacity of the sample may be due to tissue structure as well as membrane permeability.  This can  be explained i n two ways: (1) higher freezing temperature breaks the c e l l walls and produces larger cavities for water retention, (2) intact c e l l walls attained by lower freezing temperature prevent entrapped a i r from being expelled and the subsequent free passage of water. results are i n an agreement with the work of Smithies (30). TABLE 5 MEAN TOTAL WATER UPTAKE (% D.B.) OF FREEZE-DRIED BEEF IRRADIATED FRESH AND IRRADIATED AFTER FREEZE-DRYING 3,  Water uptake Dry matter wt  a  1  0  0  Fresh  Freeze-dried  15.1117  193.1037  2  average of 24 samples TABLE 6  MEAN TOTAL WATER UPTAKE ' (% D.B.) OF FREEZE-DRIED BEEF FROZEN AT DIFFERENT TEMPERATURES 3  -22°C Water "P*ake Dry matter wt  1  0  0  214.2154  average of 24 samples  -56°F 194.0000  These  24  Rehydration rate analysis Rehydration might be compared to the flow of water through a capillary:  FIGURE 3.  MODEL OF CAPILLARY FLOW  It is known that the fluid flow velocity is a function of the flow pressure difference and the length between two points. It i s : Q  -  K  A  (  )  P  N  X Q = wt/unit time  w h e r e  A  X  = length of tube  P  =  p  1  - P  2  K = constant n = coefficient  .  .  .  .  (1)  25  If a rehydration model similar to Figure 4 i s assumed water w i l l flow through the material under a pressure difference of P  Q  - P^  =4P  If i t i s assumed that the wetted interface advances as a "wetted front" into the dry material, then the pressure difference w i l l be constant, but the thickness of the layer w i l l increase.  The amount of water (dw) flowing  in time dt w i l l be related to the increase in the thickness of the wetted layer dx.' Thus we can write dx «< dw and x at w. Also  Q ^  dw dt  Hence, equation (1) can be rewritten as: d  =  w  dt  (K*)  (Ap) w  w dw = (K*) ( A p ) n  W*  +  dt  n  1  = (K ) ( A p ) 1  n + 1 .'.  n  n  (t) + C when n * 1  log W oc. log t  (2)  . . . (3)  Therefore i t would appear that the rate of water uptake should vary logarithmatically with the logarithm of time. uptake (% D.B.)  When the log water  i s plotted versus log-time, a straight line relationship  i s found (Appendix B).  This indicates that there i s a linear relationship  26  between log moisture and log time which agrees with equation (3) shown above.  It was also found that the lines found for a large number of  runs break into two parts (see graphs in Appendix B).  This would indicate  that the mechanism of rehydration proceeds in two stages which agree with the hypothesis of Auerback et a l . (1). The straight line rehydration line (see Appendix B) prior to the break in the curve i s called part 1, while the line following the break i s called part 2.  There i s also a  very rapid i n i t i a l water uptake (Table 3). Upon inspection of log log plots (Appendix B) i t i s obvious that there are considerable differences between replications. No reason has been found to explain these differences. There are several variables that were not measured i n these experiments which might contribute to this variation:  and  1)  variation i n the moisture content of the freeze-dried meat  2)  variation in fat content  3)  different tissue structure  M-) unknown differences in freezing rate  Further study w i l l be required to determine whether or not any of the above factors contributed to this variation between replications. An analysis of variance of the slope of the regression lines (Table 7) shows that the irradiation levels have a significant effect on the slope of f i r s t part of the rehydration process (part 1 of the regression analysis, see Table Bl, Appendix B).  Table 8 indicates that the control  (unirradiated) samples rehydrated significantly slower than the irradiated samples.  According to Duncan's New Multiple Range Test, there i s no  27  TABLE 7 ANALYSIS OF VARIANCE OF THE SLOPES OF THE REGRESSION LINES OF LOG (MOISTURE) vs. LOG (TIME) AS SHOWN IN APPENDIX B  d.f.  Source  S.S.  M.S.  F  3 44 47  0.1961 0.9337 1.1298  0.0653 0.0212  3.0801*  Irradiation levels^ . Experimental error Total  3 44 47  0.0955 0.6418 0.7373 • ,  0.0318 0.0145  2.1913  Irradiation sequence Experimental error Total  3  1 46 47  0.0383 1.0915 1.1298  0.0383 0.0237 .  1.6160  Irradiation sequence^ Experimental error Total  1 46 47  0.1202 0.6171 0.7373  0.1202 0.0246  8.9701**  Freezing r a t e Experimental error Total  1 46 47  0.0003 1.1356 1.1359  0.0003 0.0246  0.0121  Freezing rate* Experimental error Total  1 46 47  0.0227 0.7209 0.7436  0.0227 0.0156  1.4551  Irradiation l e v e l s Experimental error Total  3  3  3  3  part 1 of the regression line  k part 2 of the regression line ft significance at 95% level  rft  significance at 99% level  TABLE 8 COMPARISON OF THE SLOPE OF THE REGRESSION LINES FOR PART 1 OF THE REHYDRATION PROCESS AS INFLUENCED BY IRRADIATION LEVELS  0 Mrad  1 Mrad  A Slope  0.1065  a  3 Mrad  5 Mrad  B  C  D  0.2658  0.2255  0.2584  mean value of 12 samples  Duncan's New Multiple Range Test: B  D  C  A  B D C> A  Means sharing the same underline did not d i f f e r significantly according to Duncan's New Multiple Range Test  TABLE 9 COMPARISON OF THE SLOPE OF THE REGRESSION LINES (PART 2) AS INFLUENCED BY FRESH/DRY IRRADIATION SEQUENCE  Irradiated when fresh Slope  Irradiated when freeze-dried  0.0920  a  a  mean value of 24 samples  0.1921  29  significant difference between the slopes of the samples irradiated at 1, 3 and 5 megarad.  Table 7 also shows that the "fresh-dry" irradiation  sequence has a highly significant effect on the slope of the last part of the rehydration process, ("part 2" of the regression analysis - see Table B2, Appendix B). Table 9 shows that the regression lines for "part two" rehydration of samples irradiated after freeze-drying have greater slope than the samples irradiated when fresh. This indicates that the "part two" rehydration rate i s more rapid i n the sample irradated after freeze-drying than i n the sample irradiated when fresh. Extract Release Volume (ERV) In this study, the analysis of variance shows no significant difference i n ERV for different irradiation levels, freezing rates and "fresh-dry" irradiation sequences (Table 10). However the combined effect of irradiation level and fresh-dry irradiation sequence showed significant differences i n ERV at the 95% level.  Table 11 shows that  the sample irradiated at 5 megarad after freeze-drying gave the lowest ERV.  This result appears to indicate that the lower the moisture content,  the less damage occurs during irradiation. ERV i s normally measured on fresh meat of relatively uniform moisture content.  In these experiments the ERV of rehydrated samples  varying greatly i n moisture content are being compared.  For example,  sample A may reach a moisture content of 65% (W.B.) while sample B reaches only 40% (W.B.) moisture content after rehydration.  Usually the ERV  obtained i s higher i n sample A and lower in sample B. Does this truly  TABLE 10 ANALYSIS OF VARIANCE OF EXTRACT-RELEASE VOLUME OF RECONSTITUTED FREEZE-DRIEF BEEF: EFFECT OF IRRADIATION LEVELS, FRESH-DRY IRRADIATION SEQUENCE, AND FREEZING RATE  DF  Sum Sq  Mean Sq  Irradiation levels (A)  3  283.77  94.592  Fresh-dry irradiation sequence (B)  1  243.36  Source  Freezing rate (C)  1  3.3075 1489.6  243.36 3.3075  F  Prob  0.60  0.6243  1.54  0.2216  0.02  0.8573  3.14"  0.0382  0.53  0.6659  AB  3  AC  3  253.22  BC  1  348.63  348.63  2.21  0.1435  ABC  3  483.57  161.19  1.02  0.3979  Error  32  5057.0  Total  47  8162.4  496.53 84.406  158.03  significant at 95% level  TABLE 11 MEAN EXTRACT-RELEASE VOLUME (AVERAGE OF 6 SAMPLES) AS INFLUENCED BY IRRADIATION LEVEL AND FRESH-DRY IRRADIATION SEQUENCE  0 Mrad A  1 Mrad  3 Mrads  5 Mrads  C  D  B  Irradiated when fresh  61.8650  73.2317  64.0217  73.1250  Irradiated when freeze-dried  E 68.7283  F 65.4083  G 68.2217  H 51.8717  Duncan's New Multiple Range Test: B D E G F C A H  B  D E > H  32  indicate that the sample B has higher waste-holding capacity than sample A?  These differences i n water uptake serve to confound the  ERV results, and w i l l require further study. Shear Press The analysis of variance (Table 12) shows that irradiation levels have a significant effect on the shear press value of freeze-dried beef samples.  Kramer shear values of meats are low for 5 megarad  of irradiation compared to 1 and 3 megarad (Table 13).  The freeze-dried  samples subjected to 5 megarad of irradiation have a lower shear force after rehydration than do those subject to 1 or 3 megarad. The control sample (unirradiated sample) had the highest shear press value as compared to the irradiated samples.  This results agrees with Bailey and  Rhodes (3) that irradiation of meats causes a softening of texture. The change i s small at low doses such as 1, 3 megarad, and increases with higher doses of irradiation.  Bailey and Rhodes also stated that when  a tender meat i s subjected to irradiation, i t i s not over-softened and that the irradiation at sterilizing doses has a beneficial effect in respect to texture on tougher types of meat. It can be seen from Table 12 that the "fresh-dry" irradiation sequence and the freezing rate show no shear press forces. difference.  significant effect: upon the  However, their combined effect produces a significant  Sample frozen at -56.1°C (-69°F) and irradiated i n the  freeze-dried state gave a significant lower shear press value (Table 14).  TABLE 12 ANALYSIS OF VARIANCE OF KRAMER SHEAR PRESS FORCE FOR REHYDRATED FREEZE-DRIED BEEF: EFFECT OF IRRADIATION LEVELS, FRESH-DRY IRRADIATION SEQUENCE AND FREEZING RATES  Source  DF  Sum Sq  Irradiation levels (A)  3  3910.3  Fresh-dry irradiation sequence (B)  1  2.5669  Freezing rate (C)  1  F  Prob  1303.4  4.25*  0.0123  2.5609  0.01  0.8890  909.85  2.97  0.0910  Mean Sq  909.85  AB  3  1799.7  599.89  1.96  0.1391  AC  3  1028.8  342.94  1.12  0.3568  BC  1  1320.7  4.31*  0.0438  ABC  3  1699.5  566.52  1.85  0.1572  Error  32  9814.0  306.69  Total  47  2048.5  1320.7  ft  significant at 95% level TABLE 13  MEAN KRAMER SHEAR FORCE VALUES FOR REHYDRATED FREEZE-DRIED BEEF IRRADIATED AT FOUR DOSE LEVELS  Shear force  a  0 Mrad  1 Mrad  3 Mrad  5 Mrad  A  B  C  D  27.3508  28.3108  16.8083  42.2083  (lbs) a  average of 12 samples  Duncan's New Multipl.e Range Test: A  C  B  D  A > C B D C >D  Means sharing the same underline did not dffer significantly according to Duncan's New Multiple Range Test.  34  TABLE 14 MEAN KRAMER SHEAR PRESS FORCE VALUES FOR REHYDRATED FREEZE-DRIED BEEF SUBJECTED TO TWO FRESH-DRY IRRADIATION SEQUENCES AND TWO FREEZING RATES 3  Shear forces (lbs)  A  B  C  D  28.0092  29.7925  38.0875  18.8392  average of 12 samples A  o combined effect of slow freezing (-22.2 C) and irradiated when fresh  ^ combined effect of slow freezing (-22.2°C) and irradiated when freeze-dried C  o combined effect of rapid freezing (-56.1 C) and irradiated when fresh  D  combined effect of rapid freezing (-56.1°C) and irradiated when freeze-dried  Duncan's New Multiple Range Test: C  B  A  D C >D  35 CONCLUSIONS In this study, the effect of irradiation level, fresh-dry irradiation sequence and freezing rate on the extract-release volume, shear press force and rehydration were investigated. .1)  The effect of irradiation level, fresh-dry irradiation  sequence and freezing rate have no influence on the Extract-Release Volume (ERV)  but the combined effect of irradiation level and fresh-dry irradia-  tion sequence does affect the ERV.  The samples irradiated after freeze-  drying at 5 megarad level gave the lowest 2)  The lowest shear press force was obtained by high doses  (5 megarad) of irradiation. press forces.  ERV.  The control samples gave the highest shear  The fresh/dry irradiation sequence and freezing rate did  not affect the shear press measurement. 3)  The irradiation level has l i t t l e effect on the f i n a l  water absorbed by the freeze-dried beef.  The fresh/dry irradiation  sequence and freezing rate affect the water regained greatly. total water uptake was  The highest  found for the meat irradiated when fresh and frozen  at -22.2°C (-8°F) temperature. 4)  The mechanism of rehydration appears to follow a phenomena  of water flow, not diffusion, which i s similar to water flow in capillary tubes.  There appears to be three mechanisms involved in rehydration,  as shown by the fact that almost a l l log log curves were broken into  two  straight lines, and there i s a very rapid i n i t i a l water absorption. No reasons can be found for the variation in slope and position of the curves for replicate samples.  36  5)  Upon inspection of the part 1 of the slope of the re-  gression lines i t can be seen that the unirradiated samples have a significantly lower slope than the irradiated samples.  For the part 2  of the slope of the regression lines the samples irradiated when freezedried have significantly higher slope than the samples irradiated when fresh.  37  LIST OF REFERENCES  1.  Auerback, E., H. Wang, N. Maynard, D.M. Doty, and H.R. Kraybill, 1954.  A Histological and Histochemical Study of Beef  Dehydration. V, Some Factors Influencing the Rehydration Level of Frozen Dried Muscle Tissue. 2.  Bull, H.B., 1943.  Food Research 19, 557.  Physical Biochemistry. John Wiley and Sons,  New York. 3.  Bailey, A.J. and D.N. Rhodes. 1964. Ionizing Radiation. XI.  Treatment of Meats with  Changes i n the Texture of Meats. J .  Sci. Fd. Agric. 15, 504. 4. Coleby, J.B., M. Ingram, and H.J. Shepherd. 1961.  Treatment of  Meats with ionizing radiations, VI, Changes i n quality during storage of sterilized raw beef and pork. J . Sci. Fd. Agric., 12, 417. 5.  Doty, D.M. 1965.  Chemical changes i n irradiation meats.  In -  Radiation Preservation of Foods, National Academy of Sciences, National Research Council, Washington, D.C. 6. Fox, J.B., Jr., Theodora Strehler, Carl Bernofsky, and B.S. Schweigert. 1958.  Production and Identification of a Green  Pigment formed during Irradiation of Meat Extracts.  J. Agr.  Food Chem." 6, 692. 7.  Fujimaki, M., N. Arakawa, and G. Ogawa, 1961.  Effects of gamma  irradiation on the chemical properties of action and actomyosin of meats.  J. Food Sci. 26, 178.  38  8.  Fujimaki, M., and Nakajima, Y. 1958. autolysis of meats. V.  Chemical studies on the  On the change of f i b r i l l a r and  sarcoplasmic proteins during aging of meats. J. Agr. Chem. Soc., Japan 32_, 695. 9.  Hamm, R. 1960.  Biochemistry of meat hydration.  In Advances of  Food Research, 10, 355. 10.  Harper, J.C., and Tappel, A.L. 1957. products.  11.  Freeze-drying of food  Adv. Food Res. 7_, 171.  Harper, J.C, CO.  Chichester, T.E. Roberts. 1961.  Application  of dielectric heating in freeze-drying of food.  Presented at  the 1961 Annual Meeting of American Society of Agricultural Engineering. 12.  Hedin, P.A.,  G.W.  Kurtz, and R.R. Koch, 1960.  Production and  prevention of irradiation odour i n beef. Food Research 25, 382. 13.  Huxley, H.E., and Hansan, J. 1957.  Quantitative studies on the  structure of cross-striated Myofibrils. I. Investigations by interference Microscopy Biochim. et Biophys. Acta 23, 229. 14.  Jay, J.M. 1967.  Response of the phenomena of extract-release  volume and water-holding capacity to irradiated beef. J. of Food Sci. 32, 371. 15.  Kuprianoff, J. 1958.  "Bound Water" i n foods.  Aspects of the Dehydration of Foodstuffs.  In Fundamental Society of  Chemical Industry, p. 18. 16.  Kirn, J.F., Urbain, W.M.  and Czarnecki, M.J. 1956. Characteristics  of electron-irradiated meats; Stored at refrigerator temperatures. Food Tech. 10, 601.  39  17.  Kuprianoff, J . 1964. Fundamental and practical aspects of freezing of foodstuffs.  In Lyophilisation, p. 497, Louis  Rey (ed.) Hermann, Paris. 18.  Koshland, D.E., and E.B. Herr, 1957. The role of water i n enzymatic hydrolysis: general methods and i t s application to myosin. J. Biol. Chem., 228, 1021.  19.  Luyet, B. 1961. Recent developments i n cryobiology and their significance i n the study of freezing and freeze-drying of bacteria.  In Proc. Low Temperature Microbiology Symposium  Campbell Soup Co., Camden, N.J. 20.  Luyet, B.J. 1962. Effect of freezing rates on the structure of freeze-dried materials and on the mechanism of rehydration. Freeze-drying of Foods, p. 194. National Academy of Sciences, National Research Council, Washington, D.C.  21.  Lawrie, R.A., J.G. Sharp, J.R. Bendall, and B. Coleby. 1961. Treatment of meats with Ionising radiation. VIII, pH, water holding capacity and proteolysis of irradiated raw beef and pork during storage, and the ATP-ase . activity of irradiated -  rabbit muscle. J. Sci. Fd. Agric. 12, 742. 22.  LeClerg, E.L., W.H. Leonard and A.G. Clark, 1966. Field Plot Technique.  Burgess Publishing Company, Minneapolis,Mi nnesota.  55415. 23.  Meryman, H.T. et a l . 1962.  Introductory survey of biophysical and  biochemical aspects of freeze-drying. In Freeze-drying of Foods, Fisher, F.R. (ed.) National Academy of Sciences, National Research Council, Washington, D.C.  40  24.  Nemethy, G. and Scheraga, H.A. 1962. Structure of water and hydrophobic bonding i n proteins.  III. Thermcriyrtamic properties  of hydrophobic bonds i n proteins. J. Phys. Chem. 66, 1773. 25.  Nemethy, G. and Scheraga, H.A. 1962. Structure of water and hydrophobic bonding i n protein. I I . Model for the therntoiynamic properties of aqueous solutions of hydrocarbons. J . Chem. Phys. 36, 3401.  26.  Olcott, H.S., and Fraenkel-Conrat, H. 1964. Water resistance of protein. Ind. Eng. Chem. 3Js_, 104.  27.  Pauling, L, 1945. The adsorption of water by protein. J. Am. Chem. Soc. 67_, 555.  28.  Schmidt, C F . 1963. Appendix I I , Dose requirements for the radiation sterilization of food. Int. J . Appl. Rad. and Isotopes,  14, 19-26. 29.  Sparrman, B., L. Ehrenberg, and A.E. Ehrenberg. 1959. Scavenging of free radicals and radiation protection by n i t r i c oxide i n plant seeds. Acta. Chem. Scand. 13_, 199.  30.  Smithies, W.R. 1962. The influence of processing conditions on the rehydration of freeze-dried foods. In Freeze-drying of Foods.  National Academy of Sciences, National Research Council,  Washington, D.C. 31.  Steely R.G.D. and J.H. Torrie. 1960. Principles and procedures of statistics. McGraw-Hill Book Company, Ing. N.Y.  41  32.  Urbain, W.M. 1965. Radiation preservation of fresh meat and poultry. Radiation preservation of foods, p. 87.  33.  Whitehair, L.A., R.W. Brag, K.G. Weckel, G.W. Evans, and F. Heiligman, 1964. Influence of intramuscular fat level on organoleptic, physical and chemical characteristics of irradiated pork. I. High-temperature short-time pre-irradiation heat treatment.  Food Tech. 18_, 108.  34.  Week, B.M., and W.M. Garrison. 1958. Rad. Research £, 291.  35.  Wierbicki, E., M. Simon, and E.S. Jose Fhson. 1965. Preservation of meats by sterilizing doses of ionising radiation. Radiation Preservation of foods, p. 383.  36.  Wedemeyer, G., and A.M. Dollar. 1964. The role of Free and Bound water i n irradiation preservation: Free radical damage as a function of the physical state of water. 29, 525.  J . of Food Sci.  42  APPENDIX A  43  TABLE A l WATER LOSS DURING FREEZE-DRYING AND FINAL WATER CONTENT OF THE FREEZE-DRIED BEEF FOR ANIMAL NO. 6868 (GROUP A)  Treatment number  Fresh wt. <g)  Weight after freeze-drying  Water loss (D.B.)%  Freeze-dried M.C. (D.B.)%  1 2 3 4  83.62 79.12 68.09 73.19  21.26 17.77 20.22 19.59  300.78 355.55 242.90 287.22  2.55 2.99 2.63 4.98  5 6 7 8  78.61 71.27 69.66 76.10  21.13 18.74 17.41 21.33  289.91 288.86 308.98 281.83  6.58 3.06 2.96 9.76  9 10 11 12  84.70 78.96 65.90 67.08  20.82 19.96 16.57 16.80  316.14 312.63 315.86 308.60  3.04 5.77 ., 6.11 3.12  13 14 15 16  71.41 73.23 62.67 60.19  18.08 18.70 15.92 15.59  302.43 298.56 301.06 294.08  2.54 2.39 2.53 2.80  Average fresh sample moisture content = 292.17% (D.B.)  TABLE A2 WATER LOSS DURING FREEZE-DRYING AND FINAL WATER CONTENT OF THE FREEZE-DRIED BEEF FOR ANIMAL NO. 6852 (GROUP B)  Treatment number  Fresh wt. (g)  Weight after freeze drying  Water loss (D.B.)%  Freeze-dried M.C.(D.B.)%  1 2 3 4  80.06 91.70 90.28 68.37  21.88 g 24.25 23.67 18.01  272.76 284.80 289.45 288.21  2.67 2.40 2.86 3.08  5 6 7 8  67.88 86.43 89.38 70.70  17.93 22.37 25.14 18.80  291.01 296.50 262.91 287.65  4.47 3.55 2.90 4.20  9 10 11 12  68.04 62.50 58.95 69.01  17.69 16.31 15.47 18.30  293.91 295.49 294.15 289.61  3.27 4.35 4.66 4.52  13 14 15 16  74.89 77.13 63.77 61.63  19.98 20.54 16.63 17.66  286.69 287.77 295.73 288.21  4.32 4.45 4.33 3.94  Fresh sample moisture content = 299.74% (D.B.)  •  TABLE A3 WATER LOSS DURING FREEZE-DRYING AND FINAL WATER CONTENT OF THE FREEZE-DRIED BEEF FOR ANIMAL NO. 6852 (GROUP C)  Treatment number  Fresh wt (g)  Weight after freeze-drying  Water loss (D.B.)%  Freeze-dried M.C. (D.B.)%  1 2 3 4  95.90 57.98 93.88  25.90 15.15 24.76  280.42 299.41 290.91  3.76 5.91 4.22  5 6 7 8  78.73 76.26 62.18 64.48  20.89 20.73 16.25 17.17  290.47 283.52 315.03 293.03  4.91 5.85 11.46 6.35  9 10 11 12  80.17 75.38 74.60 82.76  21.75 19.59 19.60 21.69  283.18 299.71 294.54 308.52  5.44 5.25 4.97 9.58  13 14 15 16  75.29 52.70 86.76 72.31  19.58 14.03 23.07 20.17  299.53 292.78 290.51 271.73  5.28 6.23 5.23 5.13  Fresh sample moisture content = 299.74% (D.B.)  46  APPENDIX B  47'  -1.2  -0.6  0.D  LOG  FIGURE  5.  0.6  1.2  1.8  TIME.MINUTES  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 1, 2, 3, and 4 r e p r e s e n t s sample 1A, 2A, 3A, and 4A r e s p e c t i v e l y .  2.4  48/- -, v  --  r  -  -  rVI - -  -  --  •-  - --  -  L  r r si  -  -  -  ---  --  -- --  -  - ---  ...  --  -  •>  -  •  t  -  -  -  - ... ... - -  -  -—  -  --  i  i  ro -  if  -j  -  -  -  -- - -  --  -  ...  -  -  -If  -  -  I i  ! |  —i—| _i ! _  rf  -  -  i  1i 1  I  -  -  |C  r-J  -  --  1  ~i -  1  [  y  •  i I t 2n 1 •r ;  -  1  i  -  —•  t iJ .  l  - ~!  -  --  -  -  ...  \<Sf  >-  a  — l 1— 1  (  --  -  -  ... - - -  -  -  -  j - - ... - ._]_. 1 -- - -  -- -  --  --  ~1  --  -  1  --  -  1  —  -  I  -  1  rr  --  --  -  -  -  —  --  --  -  -  -_-  ... -  ^ ) u  -  '-  -  1L  -  -  --  -  - -... - -  --  -  Ai  -  --  -  -  -  -  --  -  ...  —  - --  -  -t  -- -  —  —  -  —  --  - - - - ...  - -- -  1  -  C 1  >-  i  -  3>  1  1  -I r.  /  —  j. _ i- 4  r  _  t  -  -  <  -  i cL y  -  ft  -  — —  - -  t  >/  -  --  - -  -1.2  FIGURE  D.B  —-  ... -  0.0 LOG  N  -  \  -  -  /  ... - - - - -  0.6  TIME.MINUTES  i  =)  i  — <J,  -  -  —--  -J  l )  S  -  I  \  —  -  r  -  -  -  -—  -  -  '-  E  I-  >  r  -  --  -  •  >  T  -  -  c)  -  1.2  -  —  ... - ...  -  --  1.8  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 5, 6, 7, and 8 r e p r e s e n t s sample 5A, 6A, 7A, and 8A r e s p e c t i v e l y .  -  -  -  2.4  4 9_>-  LOG TIME.MINUTES FIGURE  7.  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 9, 10, 11, and 12 r e p r e s e n t s sample 9A, 10A, 11A and 12A r e s p e c t i v e l y .  50 ---  -  -  - --  -  •  „r  -  — --  --  -  i-  --  --  —- - - -  -  -  --  -  -  --  - ...  ...  -  -  --  -  -- ...  -  --  -  --  -  -  --  -  -  -  ...  -  --  i/  -  /  -  '-  -  L  —1  1  ---  -  - -  —- -  —i ""!  •-  -  -  - \  .71  —  —-  -  L  -  -J  r.  -_ -  —  ~r  -  —- - -•  - ---  -  '4  -  - - - ...  --  -  - - - --... -- ...  -- -- -  -  ...  -- - -  -  -.._  -  -  --  --  --  -  -- -  -U / >tVI .c 3  -J  -  -  -  -  -  -  - - -...  -  —  -  --  (  -  --  -- - ----  - •- - . . . ...  --  -  ... ...  -  -  ----  -  -- -  - - —- - - - - - ... - _ - - ... - -  --- --  L  -  -  --  -  --  - - -- ... - - . . . -  -  -  --  ...  - —  -  -  —  -  r VI  (  A ! / /  -  1  tt  1i  A  i  /  ix:n  i UL.  1 J  tl  /  7 Li  / H •f  I  \  - -fir?  -  --  >  --  ...  /  f  -istu p  V  •)  »  tj  1J  -  1  -  --  --  -1.2  FIGURE  - _  -  ...  - -- -  - - ---  -0.6  -  --  ,  ---  •  / S  •  •  ...  "0.6  TIME.MINUTES  1.2  V  i -  1 -  -- -  -  -<  --  _  >  / _  0.0  -  D  /  -  LOG  8.  h.- ...  -  A  _  - 1--  -  -  -- A  B [  J f  1  -  --  i —>  1  >  -l r ry u  _  —-  -j  >  TT  -m_  /  • -J  in  --  -  f 1 / 1 1  - --  A.  /  1  --  A  -  -- —  ...  -  -  --. . . - - -  1.8  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 13, 14, 15 and 1 6 . r e p r e s e n t s sample 13A, 14A, 15A, and 16A r e s p e c t i v e l y .  2.4  1  -- -  - -- - - - - --- ...  - - --  —-  - - - .r»>  _.  — — — - - - --  rM  .r  -  -  -  -  -  --  --  IT". -  ... . . .  _  — —— — - --  0  -  -  -  -  ,.r•)  J  I.r  ~j  i  f  >  [  tv  --  -  -  -  „  --  >-  -  -_  —  -  -  I i+ H1 -  -  ...  --  -  if  7  - - -1r  — - —_ —————_t  - -- --  *f  -- -  --  _  -  -  - - ——  --  --  --  - -- -  --  -  -—  -  - ...  -  -  -  —  -j  -  |CD 1  -  --  -  -  - -  ir  i  —-  r  --  -  -  -  -  -  -  -(j  --  /\\  )  h  f  --  -  --  -  I  1 \J i  - -1  ...  -  3 =•r•111 -  i  -  --  11 1 > . i i  t—  --  1  -  j.1— pi IIJ_ 1T  --  < -L, -  -  - -•  -  —- - - - - - - > * /-  L  -  .„J_L ""i •  tr  --  -  ....  .r U  ...  -  1  - - - 1 —— ————— ——— - ...  ...  --- - - - - — ... -  --  -  - - — -- - --  ...  Lp J  -  _L  ...  -  -- - - -- - - - - -— — -- — - -- - -  --  -  -  ...  - - —-  - - - - - -  -  -  --  -  —  -  ...  51,  -  —> r— "F-  -  VI L1  -  -J  -  t  -  -  -  -  -  -  - - -- -  ...  —« -1.2  -  1 -D.B  -  -  -  0.0  LOG  FIGURE  9.  /  --  --  i  |  -a  \  --  A  -  -  •—  J.  -  4  -  -  < T  (  -  -  i 1 i — A  -  -  \  -  /  —  ...  '0.6  --  1.2  1  -- =-  -  J  -  -  -  -  --  —  --  - - -- - -  1.8  TIME.MINUTES  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 17, 18, 19, and 20 r e p r e s e n t s sample IB, 2B, 3B, and MB r e s p e c t i v e l y .  -  2.4  5 2' - - - 1 ... 4 1I i i - •—t --  -4 ^ 3-T — VI I —-4 ... -•  ±  -  1  ... -  11 u •>  - ... r _ rVI  --  --  --  .1 -I  —  -  - -  4  - ... -  -  -  ... - - -  -  -  -I  --  n  -  - ...  ~  --  -  £  ii-.  -fe  -  -  -  - -- -  -  /  -- -  -  _ i  -e  -  T  —i _  —- -  -- 1  -  -  -  -  M  I  —-  --  -  ^- ...  -  . --  -  -  --  pi  - -- --  -  --  -  -  --  i i  j j_  -  --  r i i -i r  —--4 !-  -  I  -  -  --  1 ! i  -- -  -  --  -  i :  i i u _ u 4— i i ! i; i ii i j ; : i i 1 :  !  I  - --  -  -  i i •i  I  —  ....  •  rr—— i Hiii r!_  ...  --  i  ---....  -  r  i 1 j !I LL. --14 i  ....  --j-  --  :  [ i ! i  ! !  !  ,  :  I  i • •  -  --—- - —-- ... - ... ... -  -  --  —  -  . . . --  ...—  - --  -  --  -  / \  - - ---- -  0.0  -4- S  - - ^5 ~< X  ---  -  -0.6  --  ...  --  - —---  <  ... - -- ...  - - --  0.B  "F  P  > —>.  --  g:  ---...  -  X" "  -  __. --  --  i  i  —  a - -  -  /  ---  1  !  •  ;  !  ••  !  !  "  | !  ;  ;  !  '  M _  1 -  ---  j -  1  -—  1ij n  -I-- - ! i --  : .  !  j  — _L  '  j_ 1  \ i  i!  i  _[_. ..... .... 1.2  P  - --- ...  -t  1" - s  ... --  '  |  -j-  -  D"  -  --  t I  >  p.K  ]  -  T^ -  ! i '  - - --  -  -  --  t\  - ----  .._-- -- -- - -  ...  -  --  - _..  ...  .... -  — -  L O G FIGURE 10.  --  •  i  --  -  -  -1.2  "1 i  —-  i  •  ;i :  --  -  ....  -  -  -  --  --  ----  r  *  -  ...  ru UT  --  F  . . .  3.  -  i  - --  -  -- —--  -  -  -  .... --  - -  -  —  -- -  ;  Tr -  i  r '  7  / ....  -  -  -  --  -  \  -  -—;  j  1 —  -  --  -  i  i  --  -  -  'ii  -  — Of  4  ! 1 :4  _" r  ... —1> f "4  _..  i  " 1r T " —r—  i  -  - -  -  -  A  r  -!-  —....  I"  -  _.)._  :- -  ..... --  1  -  -  i  -  -CHJ£> :ite:  ... ...L : 4 : b -  --  -  --  !  • !  -  ...  —f --  -  ... ...  -  r  -- |  - :I_L__L  --  - -- - - ._ -- ... -  -  IB t r ) _< —-C rU-^ - 1tH-- h - JOJT  -  - ...  -----ru -—— ca - - .... ' i«  - } -4  -  ... - ... ._ -  — —- -  -  :  -  - - - - 1 is —-  -  -  -  L •)  ....... - _:  - —  -- - -  —  -  ...  :  I  i  -14  i. 1 >i i1 --  i :  !  .! ! i  U  4-1  1.8  T I M E . M I N U T E S  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 21, 22, 23, and 24 r e p r e s e n t s sample 5B, 6B, 7B, and 8B r e s p e c t i v e l y .  _.[._ -2.4  •+ FIGURE l l .  0.0  0.6  LOG TIME.MINUTES  1.2  1.8  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 25, 26, 27, and 28 r e p r e s e n t s sample 9B, 10B, 11B, and 12B r e s p e c t i v e l y .  2.4  -1.2  -0.6  0.0  0.6  1.2  1.8  LOG TIME.MINUTES FIGURE 12.  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 29, 30, 31, and 32 r e p r e s e n t s sample 13B, 1HB, 15B, and 16B r e s p e c t i v e l y .  2.4  LOG TIME.MINUTES FIGURE 13.  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 33, 34, 35, and 36 r e p r e s e n t s sample 2C, 3C, 4C and 9C r e s p e c t i v e l y .  + A  SET 3 7  A  +  SET 3 8  X  SET 3 9 SET 40  <^  -1.2  -0.6  FIGURE 14.  0.0  LOG  0.6  1.2  1.8  TIME.MINUTES  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 37, 38, 39, and 40 r e p r e s e n t s sample 10C, 11C, 12C, and 5C r e s p e c t i v e l y .  ru  in rsi ru'  o  +  in  —J  ru"  X A  in »ru  C3  CQrvj o  LU  CHILLI  CM CD in  in ru in —i  A  SET  41  +  SET  42  X  SET  43  o  SET  44  -<3-  - 1.2  .  1 -0.6  FIGURE 15.  1 D.O  1 0.6  LOG TIME.MINUTES  1 1.2  1 1.8  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 41, 42, 43, and 44 r e p r e s e n t s sample 6C, 7C, 8C, and 13C r e s p e c t i v e l y .  SET  45  +  SET  46  X  SET  47  A  -1.2  FIGURE 16.  -0.6  1  1  0.0  0.B  LOG TIME.MINUTES  1.2  1.8  Logarithm o f water uptake versus l o g a r i t h m time f o r i r r a d i a t e d f r e e z e - d r i e d beef: Set 45, 46, and 47 r e p r e s e n t s sample 14C, 15C, and 16C r e s p e c t i v e l y .  $ R U \  (  EXECUTION N  BEGINS T I TIF  12  PART 1 P ART 1 3 »ART 1 4 - A P. T 1 6  q  1 s 15 3  Ia 1 5 8 3 8 ') 6 )  14 '->  ,  4 5 4 9 9 4 4 <<  r b \ >  b tl  4 5 4 4 10 6  3 1 2 9 8 9 10 1  II  'f3k  m  SET1 St:T? SCT SF T SCT SET s n SI T .',!- T SC I SCT SCT SET sn Ml  SET  ,  (,  7 P AIT 1 8 ' !i 1 '/  PART PART HART PART l ' i PARI I -. PARI  10 1 1 12 13  1 1 1 1 1 1  ! •  ) 7 ' , •' 1 1 l •' P A R I 1 K F U 1 9 PAR f ! S'* T ?'.) P A R I 1 Sf' T 2 1 Sc T 2 > Si 1 2 3 SC 1 ?4 HART 1 SCT 2-5 " A R T 1 S: T 2 6 PART 1 s r T ? 1 PARI 1 SI i 2 H P A R I ! SET 2 Q 5E T TO PART 1 SCT 11 PART 1 SI i 4 2 P !\ R T 1 p \ << I 1 Si 1 SC T }4 PA ' r i SI I 10 PART 1 s c r 3ft SET 3 7 PART 1 Sf T 3H 1'. : T ! SI !19 PART 1 c \z r AO SET 1 S T /2 SET 'i 7 SCT 44 SC T /, *, SET 4 6 PART 1 SET 4 7 SCT SCT  r  t  A  2.317C 2.2662 2.100" 1,861') 2. 103? 2.1227 1.9') 14 1.7137 2.2 79 4 I.046 3 1 .4 368 1.4 54 5 1.7773 1.2 07 3 1. 7 3 8 4 1. o n 3 2.154 3 2,0*70 2.185 3 2.126 1 ?.179ft 1.95 6 7 1.9246 2.1617 2.1842 1 .808 C 1.9713 1.7240 2.1 52 I 1.7F.9 1 1.6C05 1.5367 2.1414 2.103 9 2.045? 2.166ft 1.9 30 3 1 .9619 2.067 9 2.213C 2.0844 2.20 7 7 2.1170 2.24R9 2.0800 2 . 1 HR ft 2.0 39 7  8  R  0.C537 0.1658 0.2469 0.2899 0.1366 0. 1C9C 0.4718 0.286 1 0.0630 0.723C 0. 18B2 0.40C3 0.2965 0.64 8 4 0 . 34C2 0.5098 0 .1470 0 .1662 0.1698 0.2RC2 0. 1 0 2 5 0.2005 0 .2403 0.215C 0.1151 0.45C9 0.2299 0.3506 0.0744 0.3487 0.2C5C 0.1489 0.1346 0.3338 0.2804 0.0818 0.0784 0.C6 31 0.1085 0.046 2 0 .094? 0 .0696 0.1291 0.0604 0.0705 0.1576 0.1025  0.9990 0.9983 0.9996 0.9955 0.99R6 0.999? 0.9980 0.9992 0.99 71 0.9990 0.9999 0.998? 0.9998 0 . 9 9 79 0 . 9 96 3 0.9898 0 . 9 99 7 0.9990 0.995? 0.9989 0 . 9 9 9C 0 . 9 9 70 0 . 9 9 71 0.9968 0.9993 0.999? 0.9961 0.9986 0.9935 0.9937 0.9995 0.9844 0.9990 0.9989 0.9989 0.9988 0.9913 0.97?3 0.9909 0.9570 0.99 76 0 . 9 964 0.995? 0.9927 0.9726 0.9995 0.9929  VB ?.?633 2. 1CC4 1.8639 1.86 19 ?.1?31 2.0986 1.519ft 1.7 364 2.2353 1.391 3 1.5683 1.7343 1.7723 1 .6167 1.7384 1 . 3365 2 . C 7 74 2 . 0 6 70 2.0255 1 .8459 2.1796 1.9657 1 .9246 1 .936 7 2.0691 1.3671  r. 7414 1 . 72 40 2.1321 1.769 1 1.6CC6 1.5367 2.1414 1.7 7C 1 1.7649 2 . 1666 1.9303 1 . 9 6 19 2 . 0 6 79 2 . 1668 ? .0844 2.2077 ? . 1 170 2.2489 2.0C95 2 . 1 186 2.0397  TABLE B l . A n a l y s i s o f p a r t 1 r e g r e s s i o n l i n e s f o r r e h y d r a t i o n o f f r e e z e - d r i e d b e e f . The i d e n t i t y o f i n d i v i d u a l " s e t s " i s t h e .nue a s u s e d o n t h e g r a p h s ( s e e F i g u r e s 5-1P). A i s t h e i n t e r c e p t o f t h e r e g r e s s i o n l i n e ( l o g tirr;e = 0) ; B i s t h e slope o f the r e g r e s s i o n l i n e ; R i s the c o r r e l a t i o n c o e f f i c i e n t ; YB i s t h e i n i t i a l p o i n t o n t h e r e g r e s s i o n l i n e ; YE i s t h e f i n a l p o i n t o n the r e g r e s s i o n l i n e .  YE 2.3697 2.3777 2.1591 2.2ft 71 2.3464 2 . 3 0 35 2.0288 2.1146 2.3896 2.2C46 1 .659'? 2.1162 2.1868 2.1137 2 . 14 8 C 2.1016 2 .3C 1 3 2 . 2 2 32 2.3451 2 . 3 2 19 2 . it ? C 2.3137 2 . 3 60 2 2 . 3C2C 2.264 6 2.1232 2 .3IC9 2.2417 2 .2H4C 2 . 3 04 1 1 . 74 3 8 1.6845 2.3163 2.3373 2 . 2 4 12 2.3176 2 .C461 ?.C25C ? . 14 3 8 2.25)7 2.2618 2.3314 2 . 3 3 06 2.3664 2.2C27 2.24E8 2.2346  ~"  (  EXfXlJ 1 IONKG  I f  4 4 10 7 15 1) l  >  1i 7  12 7 6 it  (.  PS  5  6  SPT 1  PAKT2  sifi r 2 2 A R T Sri < P ART f 1 T 4 i' A r t f SET  SF r  ')  7 l J AKT 2 SC T 8 f* ART 2 S E T ') SI I ! 0 i> \". 1 2 C T T 1 1 1' *\ '< T 2 SE 1 1 2 A K T 2 SH! T1 P l\ K T 2 'A '.r 2 s r T l'l 1 i' \ ' 1 2 • >' ' •: i i 11 r ,  !  sr T 1 1 PAKT 2 sri 1«  9  SET S "1  2 ! ?2  SFT  1  l  i  1  l  ')  10 6 8 7  12 9 9 8 9 10 10 1I TABLE  I'AIU ? . 1  ;'  l  24 T ?5  Sf 1  l"\KT  2  SF PAKT 2 SF T V - • • • ; SF r PART 2  1  15 9 10 11 4 10  2 2 2  6  SI 1 1 r £ |  5  A  Tl TIF  4 9 9  >  IMS  N  si  r SF T S T r  ?1 11 t 1  SFT 3 '•  T  16  Sf  SI T SF T 3 9 St T '.II SI. 1 4 ! SE- T 4 2 err 4 3 SF T '. 4 SET AS STT '.l'l SF T ', !  B2.  • • • ' \ I  .'  • . ••:  '  PACT 2 \ <l  .'  PAKT 2  PftflT 2  1.9811  I .093 3 2.2438 7.1175 2.325 7 2.3166 2.1796 1.9*67 1 .9246 2.2882 2.2370  2.1 20 4 2.2370 1.9974 2.1 321 2.1)72 1.1531  2.212 9  PAKT 2 . P  2.354C 2.3 31 7 2.152 9 2.0976 2. 1032 2. 122 7 2.0497 1 .8634 7.2794 1 .6889 1.0826 1.7 321 2.0">72 1.7060  1.3 33 5  1  •'.\"r  SI ' SF T  sr T  "i.-i  B  3 33 0 2.2 192 2.1 (.6 (t I . 7 800 1 .P.02 >J 2.0 IB ) 2.2130 2.0844 2.2077 2.1170 2.2489 2.0R00 2.218 1 2.039 7 2.  1  ye  P.  0.9955 2.3749 0.94 9 7 2.3732 1 0.9952 2.2275 0. 128 1 0.9915 2.2869 0.1365 0.9986 2.1231 0.109C 0.9992 2.0986 0.1217 0 . 9 9 •! 3 2 . 1 6 0 2 0 . 9 9 74 0. 1865 2.1519 0.C6 3C 0.9971 2.2353 0.3214 0.9913 2.2 350 1.7372 0 . 4 4 3 2 0.9966 0.2 36 3 0.9915 2.1435 0. 1008 0.9824 2.2061 2.1669 0.2985 0 . 9 9 7 1 0.1541 0.9990 2.18 36 1 . 3 36 5 0.5098 0.9898 2. M i l 0.0672 0.9 96 5 2 . 2 8 80 0.1311 0.9887 2.3609 0 . 9830 0.0 27 1 2.3386 0.9921 0.0220 O.S590 2.1796 0.102 5 1.9657" 0.2005 0.557 0 1 .9246 0.2403 0.99/1 2.32 33 0.991 9 0.0351 0.9979 2.27/0 0.0400 0 . 9 6 Pt 1 2.2568 0.1364 0 . 9 96 3 2. 3267 0.056C 0 . 9 9 76 2.272 7 0. 1750 0 . 9 9 31 2.1321 0 .074 4 2 . 31 4 7 0.9262 0.0734 0.9986 0.4900 1 .8 2 8 5 0.997 . 0.4833 I, 7 8 1 9 2 . 3 322 0.0637 0.9856 2.351 7 0.0187 0.9820 2.29 8 8 0.0596 0.9848 2.1666 0.0818 0.9988 2 . 0 73 7 C.1833 0.9556 2.0766 0 . 2 1 0 <t 0.959! 2.1988 0 . 1803 0.9585 0.9970 0.0462 2.1668 0 . 09 4~2 " 0 . 9 9 7 6 2.08'.'," 0.9 964 2.2077 0.0696 0.129 1 0.9912 2.1170 0.0604 0.992 r 2.24 8 9 0.0705 0 . 9 72'i 2.0C95 0.0659 0.9969 2.2840 0.1025 0.9979" ~~ TT.TTVTT 0 . 0  18 C  0.0550 0 . 1 1 '.  r  Analysis of part 2 regression lines for rehydration of freeze-dried beef. The identity of individual "sets is the sfl^" as used on the graphs (see Figures 5-16). A is the intercept of the regression line (log time = n ) ; B is the slope of the regression line; K is the correlation coefficient; YB is the i n i t i a l point on the regression line; Y E is the final point on the regression line.  Yff  2.3805 2.3889 2. 3 376 2.334 1 2.3464 2 . 3 0 35 2.3284  J S  2 . 2 134  2.3896 2.34 76 1 .9992 2.2099 2.2432 2.3029 2.2U4 3 2 . 1 C 11 2 . 1606 2 . 1569 2 . 3 709 2.3630 2.3620 2,3137 2.3502 2 . 14 7 8 2.308 1 2.3521 2.3366 2.3392 2.2840 2 . 14 69 2.3185 2 . 1 19 7 2 . 1464 2.1704 2.3558 2.131/6  2.  1 38 3 2.2237 2.1512 2.2997  2 72 5 1 H 2.3314 2.3305 2.3564 2.2C27 2.3485  7.7348  1;  61  APPENDIX C  TABLE CI EXTRACT-RELEASE VOLUME OF THE REHYDRATED BEEF SAMPLES  Treatment number  Extract-release volume (ml)  Treatment number  Extract-release volume (ml) .  12 13 14 15 16  50.60 63.75 73.75 69.38 67.50  Group A 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16  64.88 84.25 65.75 77.00 77.25 66.36 73.38 73.00 66.75 37.50 40.00 40.00 76.25 73.75 66.25 27.50  Group B  Group C 1 2 3 4 5 6 7 8 9 1 Q  1 2 3 4 5 6 7 8 9 10 11  60.00 77.50 77.50 79.40 48.75 66.88 77.50 75.60 62.50 70.60 76.20  11 12 13 14 15 16  84.38 43.75 75.00 71.25 65.60 77.50 75.00 57.50 60.00 46.25 58.75 71.87 71.25 80.00 50.63  TABLE C2 SHEAR PRESS VALUE OF THE REHYDRATED BEEF SAMPLES  Treatment number  Kramer shear press (lbs)  Treatment number  Kramer shear press (lbs)  12 13 14 15 16  5.81 58.19 10.19 6.25 4.44  Group A  Group B  1 2 3 4 5 6 7 8 9 10 11 12 13 14 . 15 16  42.95 6.74 27.81 27.75 25.63 36.44 35.31 27.19 50.75 16.19 109.17 18.13 32.00 7.19 8.56 21.25  1 2 3 4 5 6 7 8 9 10 11  36.06 34.69 12.68 11.44 23.13 71.25 42.31 16.81 72.88 13.07 35.81  Group C -  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16  45.88 24.94 18.38 58.25 45.63 12.82 17.94 31.31 24.38 18.44 5.31 28.56 16.56 5.62 27.25  

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