EFFECT OF TEMPERATURE, STORAGE CONDITIONS AND LIGHT ON THE COLOR OF PREPACKAGED FROZEN MEAT W illiam E* Townsend AN ABSTRACT S u b m itted t o th e S chool o f G ra d u a te S tu d ie s o f M ichigan S t a t e U n iv e r s ity o f A g r ic u ltu r e and A p p lied S c ie n c e i n p a r t i a l f u l f i l l m e n t o f th e re q u ire m e n ts f o r th e d e g re e o f DOCTOR OF PHILOSOPHY D ep artm ent o f A nim al H usbandry 1958 EFFECT OF TEMPERATURE, STORAGE CONDITIONS AND LIGHT ON THE COLOR OF PREPACKAGED FROZEN MEAT F r e e z in g a s a method f o r p r e s e r v in g m eat h a s been u sed s in c e th e e a r l y 1900*s . D u rin g th e p a s t few y e a r s , f r o z e n m eat p r o d u c ts have become v e ry p ro m in en t b ec au se o f c e r t a i n c o n d itio n s p ro d u ced by World War I I , The dev elo p m en t o f lo c k e r p l a n t s , home f r e e z e r s to r a g e u n i t s and d i s p l a y ty p e f r e e z e r c a s e s h a s h e lp e d to a c c e l e r a t e th e w ide sp re a d a c c e p ta n c e o f f ro z e n m e a ts. I n 1947 (1 9 5 4 ), o n ly 13 f r o z e n m eat p ro ­ c e s s o r s w ere i n th e c o u n tr y . By 1953, th e number in c r e a s e d to 138, an i n c r e a s e o f more th a n 950%, O utput o f f r o z e n m eats in c r e a s e d from f i v e m i l l i o n pounds i n 1938 to 250 m il lio n pounds i n 1956 (1 9 5 6 ). F ro z en s to r a g e o f p rep ack ag ed f r o z e n meat w i l l be o f econom ic v a lu e to b o th th e p ro d u c e r and th e consum er. w i l l g iv e g r e a t e r re c o v e ry o f b o n es, f a t , e t c . P re p a c k a g in g f ro z e n m eat T here w i l l be a d i f f e r ­ ence i n t r a n s p o r t a t i o n , s to r a g e , h a n d lin g c o s ts i n f a v o r o f e i t h e r p a c k e r, p ro d u c e r o r p r o c e s s o r . P ack ag in g f r o z e n meat p ro d u ced problem s t h a t have proven to be d i f f i c u l t to s o lv e . They a r e co n cern ed w ith te m p e r a tu re , s to r a g e c o n d i­ t i o n s (w hich in c lu d e te m p e r a tu re , a i r movement, h u m id ity ), p ack ag in g m a t e r i a l s and m ethods (w hich in c lu d e v i s i b i l i t y , n e a tn e s s o f c u t and t i g h t n e s s o f w ra p ), and d i s p l a y under l i g h t . A m ajor f a c t o r a f f e c t i n g th e a t t r a c t i v e n e s s o f p rep a ck a g ed f r o z e n r e t a i l m eat i s t h e c o lo r o f th e exposed le a n . M yoglobin, th e m uscle p ig m en t, i s c h i e f l y r e s p o n s ib le f o r th e c o lo r o f le a n m eat, which u n d er v a r io u s c o n d itio n s changes from oxym yoglobin ( th e d e s i r a b l e r e d c o lo r ) to m etm yoglobin ( th e brown c o lo r so c h a r a c ­ t e r i s t i c o f m eat c o lo r d e g r a d a tio n ) . Review o f th e l i t e r a t u r e r e v e a l s some in fo r m a tio n c o n c e rn in g th e e f f e c t o f v a r io u s c o n d itio n s on d i s ­ c o l o r a t i o n i n p rep ack ag ed f r o z e n m eat, b u t l i t t l e in f o r m a tio n c o n c e rn in g th e c h a ra c te r o f t h i s d is c o lo r a tio n . The m ain p u rp o se o f t h i s s tu d y was to a tte m p t to c h a r a c t e r i z e th e c h e m ic a l s t a t e o f m yoglobin a s a f f e c t e d by v a r io u s s to r a g e c o n d i tio n s . The L ong issim u s d o r s i m uscle from U.S. Good and C hoice g rad e b e e f r i b s was u sed th ro u g h o u t t h i s s tu d y . B o n e le ss r i b s te a k s 1 in c h th i c k w ere c u t from th e w h o le s a le r i b c u t . S te a k s w ere p la c e d i n Cry-O-Wrap p l a s t i c b a g s , vacuum ized, c lo s e d w ith a Cry-O-Wrap c l i p , d ip p ed in to b o i l i n g w a te r w hich red u ced t h e s iz e o f th e bag a p p ro x im a te ly o n e - t h i r d , th u s g iv in g th e s te a k s a t i g h t w rap. P repackaged f r o z e n s te a k s u sed i n th e v a r io u s s t u d i e s w ere s to r e d in a s e l f - s e r v i c e c a s e o r i n a c i r c u ­ l a t i n g c o ld a i r w a lk - in ty p e f r e e z e r . S te a k s s to r e d in th e s e l f - s e r v i c e f r o z e n food c a s e u n d e r th e i n ­ f lu e n c e o f l i g h t w ere k e p t u n d er f lu o r e s c e n t lam ps d e l i v e r in g 56 f t c . o f illu m in a tio n . V a rio u s c o lo re d f i l t e r s were u sed i n th e stu d y con­ c e rn in g t h e a t t r i b u t e o f l i g h t t h a t may be r e s p o n s ib le f o r c o l o r d e g ra ­ d a tio n . S te a k s s to r e d u n d e r c o lo re d f lu o r e s c e n t lamps d e liv e r y in g 20 f t c , o f i l l u m i n a t i o n w ere k e p t i n th e 0°F w a lk -in f r e e z e r . M easurem ents o f s u r f a c e c o lo r o f m eat w ere made by th e u s e o f M u n sell s p in n in g d is k s as g iv e n by V o eg eli (1 9 5 2 ). E s tim a tio n o f th e p e r c e n t m etm yoglobin was e s s e n t i a l l y a s a p p lie d by Mangel (1951) and B u tle r (1 9 5 3 ). - 2 - T em p eratu re v a r i a t i o n s i n a s e l f - s e r v i c e fro z e n food c a s e a f f e c t s th e a p p e a ra n c e o f p rep a ck a g ed f r o z e n m eat packaged in tr a n s p a r e n t oxygen im perm eable w rapping m a t e r i a l s . P re h a n d lin g c o n d itio n s and r a t e o f f r e e z i n g a f f e c t s i n i t i a l c o l o r d e g r a d a tio n o f p rep ack ag ed f r o z e n m eat. R ep eated f r e e z i n g and thaw ing i n an oxygen im perm eable w rap p er h a s a marked a f f e c t on th e c o lo r o f p rep ack ag ed m e a t. W ith a l t e r n a t e f r e e z i n g and th aw in g c y c l e s , t h e r e was an i n c r e a s e o r d e c r e a s e o f m etm yoglobin f o r m a tio n . D is p la y o f p rep ack ag ed f r o z e n m eat u n d e r in c a n d e s c e n t o r f l u o r e s c e n t l i g h t i n g c a u s e s d e g r a d a tio n o f c o lo r . T em perature o f d i s ­ p la y o f p rep a ck a g ed f r o z e n m eat u n d e r f lu o r e s c e n t l i g h t i n g had an e f f e c t on c o lo r d e g r a d a tio n . Sam ples s to r e d u n d e r f l u o r e s c e n t l i g h t a t 0°F showed l e s s d i s c o l o r a t i o n and m etm yoglobin fo rm a tio n th a n sam ples s to r e d i n d a rk n e s s a t t h e same te m p e ra tu re in th e s e l f - s e r v i c e c a s e in w hich th e r e was c o n s id e ra b le tem per a ttir e f l u c t u a t i o n . Wave le n g th s o f l i g h t betw een 560 and 630 mu (y e llo w and o ran g e p o r ti o n o f t h e sp ectru m ) seem to be r e s p o n s ib le f o r c o lo r d e g r a d a tio n o f p rep ack ag ed f ro z e n m eat. F ro zen m eat s to r e d u n d er g re e n and re d f l u o r e s c e n t lam ps has b e t t e r c o lo r s t a b i l i t y b u t th e s e l i g h t s g iv e m eat an u n f a m ilia r a p p e a ra n c e . I t would ap p e a r t h a t th e l i g h t from th e y e llo w p o r ti o n (580 mu r e g io n ) o f th e sp ectru m e m itte d by w h ite f l u o r e s ­ c e n t lam ps commonly u sed f o r f ro z e n food d is p l a y c a s e s i s r e s p o n s i b le f o r c o lo r d e g r a d a tio n o f p rep ack ag ed fro z e n m eat. The fo rm a tio n o f m etm yoglobin i s th e p rim a ry cau se o f d i s c o l o r a t i o n when prep ack ag ed fr o z e n m eat i n a t r a n s p a r e n t w rapper i s exposed to l i g h t . - 3 - R e fe re n c e s Anonymous. 1954. P ack ag in g S h i f t Seen Spur To F ro zen M eats. F ro z e n F o o d s, 1 6 ( 6 ) :9 9 . Anonymous. 1956. The O u tlo o k F or F ro zen F o o d s. M ark etin g S e r v ic e . A.M .S. - 154. Q uick U .S .D .A . A g r i c u l t u r a l B u t l e r , 0 . D ., B r a t z l e r , L. J . , and M ailm an, W. L. 1953. The E f f e c t o f B a c te r ia on th e C o lo r o f P repackaged R e t a i l B eef C u ts . Food T ech n o lo g y , V o l. 7 (1 0 )3 9 7 . M angel, M a rg a re t. 1951. The D e te rm in a tio n o f M ethem oglobin i n B eef M uscle E x t r a c t s . I . A S tudy o f S p e c tro p h o m e tric M ethods. I I . F a c to r s A f f e c tin g M etm yoglobin F o rm atio n In F ro zen B e e f. U niver­ s i t y o f M isso u ri R esea rch B u l l e t i n . 474. 24 p a g e s . V o e g e li, M. 1952. The M easurement o f F re s h B eef M uscle C o lo r Change by D ish C o lo rim e try . U npublished Ph.D . T h e s is . M ichigan S t a t e C o lle g e . 125 p a g e s . - 4 - EFFECT OF TEMPERATURE, STORAGE CONDITIONS AND LIGHT ON THE COLOR OF PREPACKAGED FROZEN MEAT By W illiam E . Townsend A THESIS S u b m itted to th e S ch o o l o f G rad u ate S tu d ie s o f M ichigan S t a t e U n iv e r s ity o f A g r ic u ltu r e and A p p lie d S c ie n c e i n p a r t i a l f u l f i l l m e n t o f th e re q u ire m e n ts f o r th e d e g re e o f DOCTOR OF PHILOSOPHY D epartm ent o f A nim al H usbandry 1958 ProQuest Number: 10008609 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 10008609 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 W illia m Eben Townsend c a n d id a te f o r th e d e g re e o f D o cto r o f P h ilo so p h y F i n a l e x a m in a tio n : D is s e r ta tio n : F e b ru a ry 1 8 , 1958, 2 :0 0 P .M ., room 101 Anthony H a ll E f f e c t o f T e m p e ratu re, S to ra g e C o n d itio n s and L ig h t On The C o lo r o f P repackaged F ro zen M eat. O u tlin e o f S tu d ie s : M ajor S u b j'e c t: Anim al Husbandry M inor S u b j'e c ts : B io c h e m is try , B a c te rio lo g y B io g r a p h ic a l Ite m s : B orn, Ju n e 2 1 , 1927, H o u lto n , Maine U n d erg rad u ate S tu d ie s , U n iv e r s ity o f M aine, 1949-53 G rad u a te S t u d i e s , M ichigan S ta te C o lle g e , 1953-55 M ichigan S t a te U n iv e r s ity , 1955-58 E x p e rie n c e : Member: G ra d u ate R ese arch A s s i s t a n t , D epartm ent o f A nim al H usbandry, M ichigan S ta te C o lle g e , 1953-55 G rad u ate R e se a rc h A s s i s t a n t , D epartm ent o f A nim al H usbandry, M ichigan S ta t e U n iv e r s ity , 1955-58 S o c ie ty o f th e Sigma Xi ACKNOWLEDGMENTS The a u th o r i s d e e p ly in d e b te d to P r o f e s s o r L« J . B r a t z l e r o f th e D epartm ent o f Anim al H usbandry f o r h i s c o n tin u e d i n t e r e s t , a i d , g u id a n c e and s u g g e s tio n s d u r in g t h i s i n v e s t i g a t i o n . The a u th o r a ls o w ish es to e x p re s s h i s a p p r e c i a t i o n f o r P r o f e s s o r B r a t z l e r 1s c r i t i c a l r e a d in g o f t h i s m a n u s c rip t. H is i n s p i r a t i o n s w i l l alw ays s tim u la te th e a u th o r to p r o g r e s s fo rw a rd . To D r. R. N. C o stilo w and D r. C. A. H o p p ert, th e a u th o r w ish e s t o e x p re s s h i s a p p r e c i a t i o n f o r t h e i r c r i t i c a l r e a d in g o f t h i s man­ u s c rip t. The a u th o r w ish e s to e x p re s s h i s s in c e r e a p p r e c i a tio n to M rs. B e a tr ic e S ic h e lb e r g e r f o r h e r a id i n th e p r e p a r a tio n o f t h i s manus c rip t. To h i s w if e , L i l l y , th e a u th o r w ish es e s p e c i a l l y to acknow ledge h i s g r a t i t u d e and in d e b te d n e s s f o r s a c r i f i c e s and encouragem ent t h a t have made h i s stu d y p o s s i b l e . G r a titu d e i s e x p re sse d to v a r io u s members o f th e D epartm ent o f A nim al Husbandry f o r t h e i r a id and s u g g e s tio n s a t v a r io u s tim e s . The f i n a n c i a l a s s i s t a n c e o f M ichigan S t a t e U n iv e r s ity by a G ra d u a te R e sea rch A s s i s ta n ts h i p i s g r a t e f u l l y acknow ledged. TABLE OF CONTENTS Page INTRODUCTION.............................................................................................................. X REVIEW OF LITERATURE............................................................................................ 3 A. C h em istry o f M uscle Pigm ent (M yoglobin) . . . . . . 5 B. P h y s io lo g ic a l F u n c tio n o f M yoglobin . ......................... . 1 1 C. The C o lo r o f F re s h M e a t .................................................. . . . 1 2 D. The C o lo r o f F ro zen Meat .......................................................12 E. C h em istry o f C olor Change In F ro zen Meat F. F a c to r s I n f lu e n c in g th e C olor Changes o f F ro zen M e a t ............................................................... 1 . Oxygen P r e s s u r e and P e n e tr a tio n . . . . . 13 14 .......................14 2. P ack ag in g M ethods and M a te r ia ls ............................. . 1 6 3 . M ethods o f F r e e z i n g ....................... . . . 1 7 4 . E f f e c t o f Time, T em perature and R e la tiv e H u m i d i t y ...................... . • • • • • 1 8 5 . E f f e c t o f B io lo g ic a l A gents ...................................... , 2 1 6 . E f f e c t o f S to ra g e i n D i f f e r e n t A tm ospheres . . 21 7 . E f f e c t o f L i g h t ........................................................................ 22 PURPOSE OF STUDY...................................................................................................25 EXPERIMENTAL PROCEDURE........................................ I. I!. Sam pling P ro ced u re and Methods o f F re e z in g S to ra g e C o n d i t i o n s ....................... 26 . . . . 26 26 III. A. T e m p e r a t u r e ............................................................................ 26 B. R ep e ated Thawing and F re e z in g C. E f f e c t o f L ig h t . . * .....................-27 • • . • • • • • • . ......................30 C o lo r M easurem ent • . • • • • • • • • • • • . . • • 3 0 RESULTS AND DISCUSSION ................................ . ............................................33 A. T em p eratu re ............................................... . . . . . . . . . 1 . T em p eratu re V a r ia tio n In S e lf - S e r v ic e Case 33 . . 33 2 . T em p eratu re V a r ia tio n s I n Packaged F ro zen , S te a k s When S to re d In a S e lf - S e r v ic e Case Loaded to C a p a c i t y ......................................................* 3 4 3 . P re h a n d lin g C o n d itio n s and R ate o f F re e z in g • • 38 B. E f f e c t o f R ep eated F re e z in g and Thawing « • • . . • 46 C. E f f e c t o f L i g h t ..................................... 48 1 . C o lo r D e g ra d a tio n o f P repackaged F ro zen Meat S to re d Under In c a n d e s c e n t L ig h t ............................ 52 2* C olor D e g ra d a tio n o f P repackaged F ro zen Meat S to re d Under F lu o re s c e n t L ig h t - A P r e lim in a r y S tudy • • • • . . . ......................................... . . . 53 3 . C o lo r D e g ra d a tio n o f P repackaged F ro zen Meat S to re d Under th e Same L ev el o f I ll u m in a ti o n a t Two D i f f e r e n t Temper a tu r e s ...................... . 6 0 4 . C o lo r D e g ra d a tio n o f P repackaged F ro zen Meat S to re d Under V ario u s C olored F i l t e r s . . . . 65 5 . C o lo r D e g ra d a tio n o f P repackaged Meat S to re d Under V ario u s L ig h t F i l t e r s At th e Same L e v el o f I l l u m i n a t i o n ............................... .6 7 6 . C o lo r D e g ra d a tio n o f P repackaged F ro zen Meat S to re d Under C olored F lu o re s c e n t Lamps . . . 74 Page 7 . Com parison o f The S p in n in g D isk Method K ith S p e c tro p h o to m e tric E s tim a tio n o f M etm yoglobin f o r D e te rm in a tio n o f S u rfa c e C o lo r o f F ro zen M e a t .................................................................................. 75 ............................................................ 83 APPENDIX............................................................................................................. 85 SUMMARY AND CONCLUSIONS BIBLIOGRAPHY 103 INDEX TO FIGURES AND TABLES Page F ig u re 1 . Heme S t r u c t u r e o f M yoglobin . . . . . . . . . . . 6 F ig u re 2 . S t r u c t u r e o f M yoglobin 7 Table I . P h y sio -c h e m ic a l C o n sta n ts o f M yoglobin and Hemoglobin . . . . . .............................................. • T able I I . • • • . « • • , • • • • • C h a r a c t e r i s t i c s o f M yoglobin and Some Of I t s D e r iv a tiv e s ........................... . . . . . 9 10 F ig u re 3 . S ch em atic D iagram o f The R ole o f M yoglobin . . . 11 F ig u re 4 . S chem atic Diagram o f C o lo r Zones o f Meat D uring R apid F r e e z i n g .......................................................... . . 1 3 F ig u re 5 . T em perature o f S e lf - S e r v ic e F ro zen Food D is p la y Case • • • • • • • . • • ................... • • • • • 2 8 i F ig u re 6 . T em p eratu re o f 0°F F r e e z e r ............................................ 29 F ig u re 7 . Top View o f S e lf - S e r v ic e C a s e ........................................ * F ig u re 8 . End View D is p la y o f S te a k s I n S e lf - S e r v ic e Case • 35 F ig u re 9 . Summarized T em perature V a r ia tio n s In S e lf - S e r v ic e Case « ....................... • • • • • • • • • • • • • 3 6 T ab le I I I . Summarized T em perature V a r ia tio n In S e lf - S e r v ic e C a s e .................................... T able IV. 37 T em perature V a r ia tio n s I n S e lf - S e r v ic e Case When ................................... . . . 3 8 Loaded To C a p a c ity F ig u re 1 0 . E f f e c t o f T em perature V a r ia tio n on C olor Change o f P rep ack ag ed F ro zen S te a k s ................... • • • • • 3 9 F ig u re 1 1 . C o lo r Change o f P repackaged F ro zen S te a k s as A f fe c te d By P re h a n d lin g C o n d itio n s . . . . . 41 F ig u re 1 2 . I n i t i a l C o lo r Change as A ffe c te d by R ate o f F r e e z i n g ...................................................... 43 F ig u re 1 3 . R ate o f F re e z in g Of S te a k s In 0°F and -20°F F re e z e r . . . . • • . . .............................................. 44 Page F ig u re 1 4 . M etm yoglobin. E f f e c t o f R ep eated F re e z in g and Thawing ..................... 47 F ig u re 1 5 . D e g ra d a tio n o f C olor As A ffe c te d by R epeated F r e e z in g and T h a w i n g ................................................... 49 F ig u re 1 6 . Wave L en g th R egions and E n e rg ie s o f R a d ia tio n I n C a lo r ie s P er M o l e ................................................ 5 1 F ig tire 1 7 . D e g ra d a tio n o f C olor o f P repackaged F ro zen S te a k s S to re d In D arkness and Under In c a n d e s c e n t L ig h t. Metm yoglobin-r E f f e c t o f In c a n d e s c e n t L ig h t ................................................................... 54 F ig u re 1 8 . A b s o rp tio n S p e c tra For E x tr a c ts From P rep ack ag ed F ro ze n S teak s S to re d In D arkness and Under 56 F o o t-c a n d le s o f In c a n d e s c e n t I llu m in a t io n 55 F ig u re 1 9 . D e g ra d a tio n o f C olor o f P repackaged F ro z e n S te a k s S to re d In D arkness and Under F lu o r e s c e n t I llu m in a tio n . . . . . .......................................... 57 F ig u re 20. M etm yoglobin P repackaged F ro zen S te a k s S to re d I n D ark n ess and Under F lu o r e s c e n t I llu m in a tio n 58 F ig u re 21. A b s o rp tio n S p e c tra For E x tr a c t s From P repackaged F ro zen S te a k s S to re d i n D arkness and Under F lu o r e s c e n t I llu m in a tio n F or One Day and T h i r t y - f i v e Days o f S to ra g e ...................... . . 5 9 F ig u re 2 2 . D e g ra d a tio n o f C o lo r o f P repackaged F ro zen S te a k s S to re d In D arkness and Under F lu o r e s c e n t I ll u m i n a tio n a t Two D if f e r e n t T em p eratu res — Im m ediate R e a d i n g s ...................... 61 F ig u re 23. D e g ra d a tio n o f C olor o f P repackaged F ro zen S te a k s S to re d In D arkness and Under F lu o r e s c e n t I ll u m i n a t io n a t Two D if f e r e n t T em p eratu res 4 Hour "Bloom P e rio d " ........................... . . . . 6 2 F ig u re 2 4 . M etm yoglobin. P repackaged F ro zen S te a k s S to re d I n D arkness and Under F lu o re s c e n t I llu m in ­ a t i o n a t Two D i f f e r e n t T em peratures Im m ediate R eadings . . . . . . . . . . . . 6 4 Page F ig u re 24a. M etm yoglobin. P repackaged F ro zen S te a k s S to re d I n D arkness and Under F lu o r e s c e n t I llu m in ­ a t i o n a t Two D i f f e r e n t T e m p e ratu res—4 Hour ,rBloom P e r io d 1*. ...................... 64a T able V. M etm yoglobin. E f f e c t o f V ario u s C olored F i l t e r s ................................ ............................................ 67 F ig u re 25. D e g ra d a tio n o f C olor o f P repackaged F ro zen S te a k s S to re d Under V ario u s C o lo red F i l t e r s . . . 68 F ig u re 26. A b s o rp tio n S p e c tr a For E x tr a c ts From S te a k s S to re d Under V ario u s C olored F i l t e r s . . . 69 T ab le V I. M etm yoglobin. E f f e c t o f V ario u s C olored F i l t e r s a t Same L e v el o f I llu m i n a tio n . . . . . . . 7 0 F ig u re 27. D e g ra d a tio n o f C olor of P repackaged F ro zen S te a k s S to re d Under V arious C olored F i l t e r s a t Same I ll u m i n a tio n . . ............................ . . . . . . 7 1 F ig u re 28. M etm yoglobin. E f f e c t o f V ario u s C olored F i l t e r s a t Same L e v e l o f I H u m i n a t i o n ...................... . . 7 2 F ig u re 29. A b s o rp tio n S p e c tr a F or E x t r a c ts From P repackaged F ro zen S te a k s S to re d Under V ario u s C o lo red F i l t e r s a t th e Same L e v el o f I ll u m in a tio n • 73 T ab le V II. C o lo r, P h o sp h o ru s C o atin g and Dominant Uave L ength E m itte d by V ario u s F lu o re s c e n t Lamps . . . 74 F ig u re 30. D e g ra d a tio n o f C o lo r o f P repackaged F ro zen S te a k s S to re d Under V ario u s C olored F lu o r e s c e n t Lamps . . . • • • . . • . . • . • • • • . . 7 6 F ig u re 31. M etm yoglobin. E f f e c t o f V ario u s C olored F lu o r e s ­ c e n t Lamps on C olor D e g ra d a tio n o f P repackaged F ro ze n S te a k s ................................................................ 77 F ig u re 32. C o r r e l a t io n Between Index o f F ad in g and P e r c e n t M etm yoglobin o f S te a k s S to re d In D arkness In S e lf - S e r v ic e Case — Im m ediate R ead in g s, T r i a l I ............................................ 79 Page F ig u re 33. C o r r e l a t io n Between In d ex o f F ading and P e r c e n t M etm yoglobin o f S te a k s S to re d I n D arkness I n S e l f - S e r v ic e C ase, T r i a l I I . . . . . . 80 F ig u re 34. C o r r e l a t io n Between Index o f F ad in g and P e r c e n t M etm yoglobin o f S te a k s S to re d Under 56 F o o tc a n d le s o f F lu o re s c e n t I llu m in a tio n In 0°F 81 F r e e z e r ............................... F ig u re 35. C o r r e la tio n Between Index o f F ading and P e r c e n t M etm yoglobin o f S te a k s S to re d Under 56 F o o tc a n d le s o f F lu o re s c e n t I llu m i n a tio n I n S e l f S e rv ic e Case - F our Hour "Bloom ing P e rio d " 82 LIST OF APPENDIX TABLES Page A. D ata C o lle c te d On T em perature V a r ia tio n In The S e l f S e r v ic e Case . . 85 B. D ata C o lle c te d On T em perature V a r ia tio n I n S e lf - S e r v ic e Case When Loaded To C a p a c ity • • • • • • • • • • • 8 6 C. D ata C o lle c te d D. D ata C o lle c te d On R ate o f F re e z in g I n 0°F and -20°F ................................................................... 88 F re e z e r On P re h a n d lin g C o n d itio n s ................... 87 E. D ata C o lle c te d On R epeated Thawing and F re e z in g o f P rep ack ag ed F ro zen S te a k s • • • • • • • • • • . • • 9 0 F. D ata C o lle c te d On P repackaged F ro zen S te a k s S to re d In D ark n ess and Under In c a n d e sc e n t I llu m in a tio n . . . 92 G. D ata C o lle c te d From S te a k s S to re d In th e S e lf - S e r v ic e Case In D arkness and Under F lu o r e s c e n t I llu m in a t io n 93 H. D ata C o lle c te d From S te a k s S to re d In D arkness and Under 56 F o o t-c a n d le s o f F lu o re s c e n t I llu m in a tio n At Two D i f f e r e n t T em p eratures . • • • ................................. , . 9 5 I. D ata C o lle c te d From P rep ack ag ed F ro zen S te a k s S to re d In D ark n ess and Under V arious C olored F i l t e r s • • • • 97 J. D ata C o lle c te d From P repackaged I?ro z e n S te a k s S to re d I n D ark n ess and Under V ario u s C olored F i l t e r s At th e Same L ig h t I n t e n s i t y ........................... 100 K, D ata C o lle c te d From P repackaged F rozen S te a k s S to re d In D arkness and Under V ario u s C olored F lu o re s c e n t L am ps • • • • 102 INTRODUCTION F re e z in g a s a m ethod f o r p r e s e r v i n g meat h a s b een u sed s in c e th e e a r l y 1900*s# D uring th e p a s t few y e a r s f r o z e n m eat p r o d u c ts have become v e ry p ro m in e n t b e c a u se o f c e r t a i n c o n d itio n s p ro d u ced by World War I I# The d e ­ v elopm ent o f lo c k e r p l a n t s , home f r e e z e r s to r a g e u n i t s and d i s p l a y ty p e f r e e z e r c a s e s h a s h e lp e d to a c c e l e r a t e th e w ide s p re a d a c c e p ta n c e o f f r o z e n m eats* In 1947 (Anonymous, 1 9 5 4 ), o n ly 13 f r o z e n m eat p r o c e s s o r s w ere i n th e c o u n tr y . th a n 950%# By 1953, th e number had in c r e a s e d to 138, an i n c r e a s e o f more O u tp u t o f f r o z e n m eats in c r e a s e d from f i v e m i l l i o n pounds i n 1938 to 125 m i l l i o n pounds i n 1952, and to 250 m il l i o n pounds i n 1956 (Anony­ m ous, 1 9 5 6 ). T h is i n d i c a t e s t h a t th e program f o r e x p erim en tal, a d ju stm e n t o f p re p ac k ag e d f r o z e n m eat and th e ground work f o r th e “ evolution** o f f r o z e n m eat i s slo w ly b e in g l a i d by g ra d u a l i n t r o d u c t i o n o f f r o z e n s t e a k s , c h o p s, e tc . F r e e z e r s to r a g e o f f e r s a means tow ard e q u a liz in g th e s u p p ly o f f r e s h m eats a v a i l a b l e a t a l l s e a so n s o f th e y e a r . b o th th e p ro d u c e r and t h e consum er. T h is i s o f economic v a lu e to P rep ac k a g in g f r o z e n m eat w i l l g iv e g r e a t e r r e c o v e ry o f b o n e s, f a t , and trim m ings w hich can be c o n v e rte d i n t o more u s e f u l and v a lu a b le p r o d u c ts . T here w i l l be a d i f f e r e n c e i n t r a n s ­ p o r t a t i o n , s to r a g e , h a n d lin g , and p ack ag in g c o s ts in f a v o r o f e i t h e r th e p a c k e r, p ro d u c e r o r p r o c e s s o r . C e n tr a liz e d c u t t i n g , trim m in g , f r e e z i n g and p a c k a g in g o f m eat a t th e p a c k in g p l a n t would e lim in a te shipm ent o f b u lk c a r c a s s e s and sa v e f r e i g h t c o s ts i n f a v o r o f th e consum er, p ro d u c e r o r p ro c e sso r. However, t h e method o f p ack ag in g f ro z e n meat gave r i s e to many p r o ­ b lem s, th o u g h th e y seem to be fe w e r, b u t more d i f f i c u l t to s o lv e . These p ro b lem s a r e c o n ce rn e d w ith te m p e r a tu r e , s to r a g e c o n d itio n s (w hich in c lu d e te m p e r a tu r e , a i r movement, h u m id ity ), p ack ag in g m a te r ia ls and m ethods (w hich in c lu d e v i s i b i l i t y , n e a tn e s s o f c u t and t i g h t n e s s o f w rap) and d i s p l a y under lig h t* A m ajo r f a c t o r a f f e c t i n g th e a t t r a c t i v e n e s s o f p rep ack ag ed f r o z e n r e t a i l m eat c u t s i s th e c o lo r o f th e exposed lean * The c o lo r o f m eat and m eat p r o d u c ts i s o f g r e a t im p o rta n c e i n our sy ste m o f m eat mar­ k e tin g . Changes i n c o lo r a r e l a r g e l y u t i l i z e d by t h e r e t a i l e r and th e m eat t r a d e a s an i n d i c a t i o n o f m eat q u a lity * Consumers a r e v e ry c r i t i c a l o f m eat c o lo r and d i s c r i m i n a t e a g a in s t meat c u ts t h a t show d is c o l o r a ti o n * M yoglobin, th e m u scle p ig m e n t, i s c h i e f l y r e s p o n s ib le f o r th e c o lo r o f l e a n m eat, w hich u n d er v a r io u s c o n d itio n s changes from oxym yoglobin ( th e d e s i r a b l e r e d c o lo r ) to m etm yoglobin ( th e brown c o lo r so c h a r a c t e r ­ i s t i c o f m eat c o l o r d e g r a d a tio n . I n re v ie w in g th e l i t e r a t u r e on th e c o lo r o f m eat, i t becomes a p p a r e n t t h a t r e p o r t s d e a lin g w ith c o lo r d e g r a d a tio n o f p re p ack ag ed f r o z e n m eat p e r se a r e l i m i t e d , and s in c e i t h as been shown by A lle n (1948) t h a t c o lo r i s v e ry im p o rta n t f a c t o r i n p rep ack ag ed m eat s a l e s , i t would seem t h a t any s tu d y o f th e f a c t o r s in v o lv e d would be b e n e f i c i a l to th e m eat i n d u s t r y . - 2 - REVIEW OF LITERATURE A re v ie w o f t h e l i t e r a t u r e r e v e a le d some i n v e s t i g a t i o n s on d i s c o l o r ­ a t i o n o f f r o z e n m e a t. Much o f th e r e s e a r c h h a s been done w ith ground b e e f . The i n v e s t i g a t o r s b e lie v e d t h a t i f t h e r e w ere g o in g to be c o lo r c h a n g e s, i t would b e a c c e l e r a t e d by th e l a r g e s u r f a c e a r e a e x h ib ite d by ground b e e f . S tu d ie s c o n c e rn in g th e d i s c o l o r a t i o n o f p re p a c k a g e d f r o z e n meat i n th e fo rm o f s te a k s a s d is p la y e d tin der s to r e c o n d itio n s a r e r a t h e r l i m i t e d . I n o r d e r to u n d e rs ta n d th e e f f e c t o f v a r io u s c o n d itio n s on th e c o lo r change o f m e a t, i t i s e s s e n t i a l t h a t one have a th o ro u g h know ledge o f th e c h e m is try o f th e m u scle pigm ent (m y o g lo b in ). The b r i g h t r e d c o l o r o f f r e s h , c u re d , and f r o z e n m eat, a s w e ll as c o lo r d e g r a d a tio n , i s due to th e ch e m ic a l s t a t e o f th e pigm ent c a l l e d m yoglobin ( fo rm e rly r e f e r r e d to a s m uscle h em o g lo b in ). I t was i n t e r ­ e s t i n g to go th ro u g h th e l i t e r a t u r e and n o te t h e many i n t e r e s t i n g t h e o r i e s r e g a r d in g th e t r u e c h a r a c t e r o f a pigm ent co n n e c te d w ith th e m u scu lar sub­ s ta n c e , As e a r l y a s th e b e g in n in g o f th e e ig h te e n th c e n tu r y , i n q u i r i e s w ere made r e g a r d in g th e o r i g i n o f t h e c o lo r o f th e m u scle. B oerhave (1739) was o f th e o p in io n t h a t i t was d e riv e d fro m blood and co u ld be washed away w ith i t . H ild e r b ra n d t (1789) m a in ta in e d t h a t t h e c o lo r o f t h e m u scu lar t i s s u e was c o n n e cted w ith i t s g r e a t q u a n ti ty o f b lo o d v e s s e l s , b u t a l s o p o in te d o u t t h a t th e s tr o n g e r th e "body” th e r e d d e r th e m uscle and b lo o d . B ic h a t (1803) p u rsu e d th e same l i n e o f th o u g h t, and s t a t e d t h a t th e m uscle d id n o t ta k e i t s c o lo r from th e c i r c u l a t i n g b lo o d , b u t from t h a t w hich b e­ came d e p o s ite d i n th e t i s s u e * 3- From 1803 t o 1886 many t h e o r i e s w ere d ev elo p ed r e g a r d in g t h e n a t u r e o f t h e m uscle p ig m e n t. D u rin g th e y e a r s 1886 to 1890, a g r e a t i n t e r e s t d e v elo p ed r e g a r d in g th e n a t u r e o f t h e pigm ent i n m u sc le . MacMunn (1886) d e m o n stra te d t h a t a p ig m en t c o u ld be e x tr a c te d from m u sc le s , and t h a t t h i s p ig m en t gave r i s e to d e c o m p o sitio n p r o d u c ts w hich w ere r e l a t e d to hemo­ g lo b in , b u t n e v e r t h e l e s s n o t i d e n t i c a l w ith th e d ec o m p o sitio n p r o d u c ts o f t h i s l a t t e r s u b s ta n c e . He a p p lie d th e te rm ,,nQrohematinn to t h i s s u b s ta n c e . He a ls o assum ed t h a t t h i s new s u b s ta n c e had som ething to do w ith th e s to r i n g o f oxygen i n f r e s h m u sc le . I n 1 8 97, K. A. H. M orner (1897) was a b le to r e p o r t t h a t he had p ro v ed t h a t th e a b s o r p tio n sp e ctru m o f m uscle pigm ent was n o t i d e n t i c a l w ith t h a t o f h em oglobin, and t h a t th e s e two s u b s ta n c e s w ere q u i t e d i f f e r e n t . M orner (1 8 9 7 ), th ro u g h h i s w a te r e x t r a c t s on m u scles o f d o g s, c a t t l e , and h o r s e s , showed t h e d is p la c e m e n t to th e re d p a r t o f th e sp ectru m o f m yoglobin a s com pared to hem oglobin* G u n th er (1 9 2 1 ), a s a r e s u l t o f h i s f i n d i n g s , was co n v in ced t h a t m uscle p ig m en t was n o t i d e n t i c a l w ith hem oglobin, and sug­ g e s te d and u se d th ro u g h o u t th e r e s t o f h is w ork, f o r th e f i r s t tim e , t h e te rm f,m yoglobinH. I n 1926, W hipple (1926) d id many e x t r a c t i o n te c h n iq u e s , i n o r d e r to g e t an e s tim a te on th e m yoglobin c o n te n t o f m u sc le s . D uring th e n e x t few y e a r s , a s e r i e s o f p u b l i c a t i o n s fo llo w e d i n w hich th e occuartence o f m yoglobin and i t s c h e m ic a l c o n d itio n s w ere s u b je c te d t o more co m p reh en siv e a n a l y s i s . T h e o r e l l 's (1932, 1934) c o n c lu s iv e c o n t r i ­ b u tio n s to th e r e s e a r c h r e g a rd in g th e n a tu r e o f m yoglobin w ere p r e s e n te d i n 1932 and 1934. I t was i n 1932 t h a t T h e o re ll succeeded i n c r y s t a l l i z i n g m yoglobin w hich gave c h e m is ts and p h y s io l o g i s t s new grounds f o r c o n tin u e d -4 - r e s e a rc h * S chenk, H a ll and King (1934) found i n t h e i r work t h a t t h e myo­ g lo b in c o n te n t i n r ib e y e m uscle o f b e e f d id n o t d i s c l o s e any p a r a l l e l i s m w ith th e hem oglobin c o n te n t* D uring th e y e a r s betw een 1934 to th e p r e s e n t tim e much r e s e a r c h h a s b een g o in g on to b e t t e r u n d e rsta n d th e c h e m ic a l ch an g es t h a t o c c u r i n m uscle due to t h i s pigm ent ltm yoglobin,? and i t s v a r io u s d e r i v a t iv e s * C h e m istry o f M yoglobin M yoglobin and hem oglobin b elo n g to th e group o f h e m o -p ro te in s , com­ p r i s i n g a p r o s t h e t i c g ro u p , p r o to p o r p h r in and a p r o t e i n com ponent, v i z , g lo b in . The fo rm e r c o n s i s t s o f f o u r p y r r o l r i n g s i n th e c e n te r o f w hich an i r o n atom i s co u p led to th e f o u r n itr o g e n ato m s, th u s making th e p o r­ p h y r in an i r o n p o r p h y rin . Bound to t h i s ir o n atom i s th e f u n c t io n , e s s e n t i a l to th e h e m o -p ro te in s , o f a r e s p i r a t o r y p ig m en t. The s t r u c t u r e o f th e heme p a r t o f th e m o le cu le i s shown i n F ig u re 1 (1956)* Only f o u r o f th e s i x v a le n c e s o f th e i r o n atom a r e co n n ected w ith th e n i t r o g e n o f th e p y r r o l r i n g s . Kendrew (1 9 4 9 ). The o t h e r two seem to be bound to th e p r o t e i n com ponent, T h e o r e l l f s works (1932, 1934 and 1947) o f f e r e d compre­ h e n s iv e know ledge o f th e c h e m is try o f m yoglobin. H is works showed t h a t th e i r o n c o n te n t o f iqyoglobin was i d e n t i c a l w ith t h a t o f hem o g lo b in , v i z , 0 .3 4 5 p e r c e n t . Kendrew (1949) p ro p o sed th e fo llo w in g s tr u c t u r e o f m yoglobin a s shown i n F ig u re 2 . He b e lie v e d t h a t th e s tr u c t u r e o f i^yoglobin i s c o n s t i t u t e d by two d i s c s , 57.8 d ia m e te r and 9$ t h i c k , p a r a l l e l to each o th e r and p e r ­ p e n d ic u la r to t h e i r a x i s , s e p a ra te d by a la y e r o f l i q u i d o f c r y s t a l l i z a t i o n 6 .6 $ t h i c k . Each o f th e d i s c s i s form ed by one p o ly p e p tid e c h a in , f o ld e d -5 - G lo b in H-N H-N- C—C I C*0 H H=C. C-H V CHo * CH -C CH = CH. N H-C C Fe C-H + 2ff CH. CH. CH2 CHr CH, CH Heme S t r u c t u r e o f M yoglobin F ig u re 1 S c h w e ig e rt, B. S . 1956. P ro c . o f th e E ig h th R e search C o n fe re n c e , Univ. o f C h icag o , C h icag o , I l l i n o i s , pg 6 1 -6 4 . -6 - b S t r u c tu r e o f M yoglobin F ig u re 2* on i t s e l f i n f o u r e q u a l s e c t i o n s . The p r o s t h e t i c group (p ro to fe rro h e m e ) i s p e r p e n d ic u la r to th e p la n e o f each d i s c and e x te n d s above and below i t , i t s th ic k n e s s b e in g a b o u t 15& g r e a t e r th a n t h a t o f th e d i s c i t s e l f * He fo u n d i n S vedberg*s u l t r a c e n t r i f u g e a s e d im e n ta tio n c o n s ta n t f o r myo­ g lo b in o f 2 .0 X lO - M . The m o le c u la r w e ig h t o f 34,000 r e p o r te d by T h e o r e ll (1932) was l a t e r c o r r e c te d by S vedberg (1939) to a m o le c u la r w e ig h t o f a b o u t 1 7 ,0 0 0 , w hich conform ed w ith th o s e o f P o iso n (1 9 3 7 ), and Roche (1 9 4 0 ). Bowen (1948) r e p o r te d a m o le c u la r w e ig h t o f 1 6 ,4 0 0 and an i r o n c o n te n t o f 0 .3 2 3 p e r c e n t . The i s o e l e c t r i c p o i n t o f m yoglobin was found to be pH 6 .9 9 . The c o m p o sitio n o f th e g lo b in component o f th e d i f f e r e n t s p e c ie s o f a n im a ls h a s been a n a ly z e d by R o s s i- F a n e l li (1940, 1941, 1942, 1947, 1948, 19 5 4 , 1955 and 1 9 5 6 ). He n o tic e d t h a t m yoglobin had is o l e u c i n e b u t no c y s t i n e i n t h e g lo b in p o r t i o n , a s c o n tr a s te d w ith hem oglobin w hich c o n ta in s -7 - c y s t i n e b u t no i s o l e u c i n e . R a th e r th a n to g iv e a f u r t h e r d is c u s s io n on th e p h y s io -c h e m ic a l c o n s ta n ts o f m yoglobin and hem oglobin, t h e a u th o r b e l i e v e s t h a t more in f o r m a tio n can be d e riv e d fro m o b s e r v a tio n o f th e f o llo w in g T a b le s I and I I . -8 - T ab le I . P h y s io -c h e m ic a l C o n sta n ts o f M yoglobin and Hem oglobin P h y s io -c h e m ic a l C o n s ta n t M yoglobin (Mb) Hemoglobin (Hb) P r o s t h e t i c Group P ro to fe rro h e m e Pro t o f errohem e M o le c u la r ¥ e i g h t 17,000 68,000 0.34/* 0 .3 4 / I r o n C o n te n t Form o f D i s s o c i a t i o n Curve H y p erb o lic Sigm oid E f f e c t o f pH on th e D i s s o c i a t i o n Curve L ittle M oderate O x id a tio n to "Met11 Very E a s ily L e ss E a s ily Oxygen A f f i n i t y L arge M oderate R a p id ity o f F i x a t i o n a t pH 7 . 4 , 20°C, m illim o le ” l sec"^- CO..........300 02 ..........19,000 130 4 ,0 0 0 R a p id ity o f D i s s o c i a t i o n a t pH 7 . 4 , 20°C s e c ”1 CO..........0 .0 4 02 »•*»«37 0 .0 0 4 40 6 .9 9 6 .7 8 S o lu b ility Very s o lu b le L ess s o lu b le R e s is ta n c e to D e n a tu r a tio n By A l k a l i i L arge Sm all I s o e l e c t r i c P o in t Taken fro m MLes P ig m en ts M u s c u la ire s : Ro s s i - F a n e l l i (1950)* p h y s io p a th o lo g ie " by A le ssa n d ro -9 - T ab le I I , C h a r a c t e r is t ic s o f M yoglobin and Some o f I t s D e r iv a t iv e s Di s tin g u is h in g C hem ical C h a r a c te r s C olor A b s o rp tio n P eak s (mu) M yoglobin MbH20 (Fe*2 ) P u r p lis h Red 555 Oxymyoglobin Mb02 B r ig h t Red 544,582 M etm yoglobin MMbOH (F e+3) B row nish Red 510,635 N i t r i c O xide M yoglobin MbNO (Fe*2 ) P in k is h Red 544,575 Carboxymyo g lo b in MbCO (F e+2) Red 540,570 Sulfmyo g lo b in Mb S (Fe*2 ) G reen Name (Fe*2 ) (5 4 0 ),6 1 7 ,6 2 0 Taken fro m "C h em istry o f Meat Pigm ents*1 by B* S* S c h w e ig e rt (1950)* -1 0 - P h y s io lo g ic a l F u n c tio n o f M yoglobin The ad v an ces i n th e n i n e te e n - tw e n t ie s and t h i r t i e s , i n th e f i e l d o f r e s p i r a t i o n p h y s io lo g y , n a t u r a l l y in v o lv e d a c l o s e r stu d y o f th e r o l e o f m yoglobin a s a r e s p i r a t o r y pigm ent* Fundam ental f a c t s w ere p r e s e n te d by T h e o re l'l (1934) and H i l l (1933, 1 9 3 6 ), and f u r t h e r in v e s t i g a t e d by M i l l i k an (1936-1939)* No r e a l l y new v ie w p o in t h a s been added to th e d is c u s s io n s in c e M i l l i k a n ! s s tu d ie s * F ig u re 3 i l l u s t r a t e s s c h e m a tic a lly th e i n t e r ­ p r e t a t i o n o f th e r o l e o f m yoglobin (B io rc k , 1 9 4 9 ), Oxygen i n A lv e o la r A ir Pulm onary C a p i l l a r i e s -----------A r t e r i a l b lo o d Venous b lo o d 0 2 « # te n s io n 02 0 2 * * te n s io n 100mm Hg 0 2 **s a t u r a t i o n 95% 40mm Hg * .s a tu ra tio n 70% P e rip h e ra l C a p illa ry (venous end) 0 2 * .t e n s i o n 40 mm Hg 4 0 2 * •s a t u r a t i o n 70% P e r ip h e r a l C a p illa r y ( a r t e r i a l end) 0 2 * •te n s io n 100mm Hg 02**s a t u r a t i o n 95% 02 The M uscle C e ll M yoglobin1s ? R e s p ir a to r y Enzymes: Cytochrome o x id a s e ^ H+’ Cyto chrome a Cytochrom e c Cytochrom e b C e l l u l a r M etabolism ^ F ig u re 3 -1 1 - The C o lo r o f F r e s h Meat The c o lo r o f f r e s h m eat and th e mechanism o f th e r e a c t i o n s w hich c a u se v a r io u s d i s c o l o r a t i o n s , m ain ly m etm yoglobin (b ro w n ), have been r e p o r te d by th e f o llo w in g a u t h o r s , o n ly to m ention a few o f them : A lle n , 1948; B ak er, 1954; B ro o k s, 1929; 1931, 1933, 1935, 1937, 1948, 1955; B u tle r , 1953; Coleman, 1951; H e is s , 1933; H oagland, 1914; Kennedy and H h ip p le , 1926; K r a f t , 1952; L a n d ro ck , 1955; L a v e rs , 1948; Moran, 1935; P en ro d , 1954; R i k e r t , 1952; U rb a in , 1952; M hipple, 1926 a and b ; and H in k le r , 1939 a and b . The C o lo r o f F ro z e n Meat Meat when f r o z e n a f t e r i t h a s been o x y g en ated h a s a d e s i r a b l e r e d c o l o r t h a t t h e consum er p r e f e r s i n a p ie c e o f m eat. However, t h i s d e s i r a b l e r e d c o l o r d o es n o t l a s t long due to v a r io u s f a c t o r s , such a s , ty p e o f w ra p p e r, s to r a g e c o n d itio n s (su c h a s l i g h t , te m p e r a tu re , r a t e o f f r e e z i n g , e tc .). F u r th e r e x p la n a tio n w i l l be g iv e n i n th e s e c tio n on f a c t o r s i n ­ f lu e n c in g th e d i s c o l o r a t i o n o f prep ack ag ed f r o z e n m e a t. Moran and B rooks (1932) p o in te d o u t t h a t when m uscle i s f r o z e n v e ry r a p i d l y , e . g . , i n l i q u i d a i r , i t i s p a le and y e llo w to p in k i n c o lo r i n th e f r o z e n s t a t e , w h ereas i f i t i s f ro z e n s lo w ly , e . g . , i n a i r a t -3 °C , i t i s deep r e d . The d i f f e r e n c e i n c o lo r i s r e a l l y an o p t i c a l e f f e c t due to d i f f e r e n c e s i n t h e s i z e o f i c e c r y s t a l s . Hhen th e c r y s t a l s a r e s m a ll t h e r e i s l e s s p e n e t r a t i o n o f t h e i n c id e n t l i g h t due to r e f l e c t i o n and r e ­ f r a c t i o n a t t h e i n t e r f a c e s betw een th e c r y s t a l s and th e s u rro u n d in g medium. They e s t a b l i s h e d th e f o llo w in g sch em atic diagram i n o r d e r to show t h i s phenomena: -1 2 - D ir e c tio n o f F ib e r s F re e z in g S u rfa c e Red Zone ->• Yellow to P in k Zone I n te n s e Y ellow Zone W ith R apid F re e z in g F ig u re 4 . Moran (1935) f u r t h e r s t a t e d t h a t i n f r o z e n m eat th e l o s s o f c o lo r i s th o u g h t to be due to th e s c a t t e r i n g o f l i g h t by th e m inute a i r b u b b le s i n th e t i s s u e o r i g i n a l l y o cc u p ied by th e ic e c r y s t a l s . C h em istry o f C o lo r Change In F ro zen Meat The oxyrayoglobin^=^m yoglobin^5:m etm yoglobin r e a c t i o n p la y s an im p o rta n t p a r t i n th e p ack ag in g o f f r o z e n m eats ( B r a t z l e r , 1 9 5 5 ). M yoglobin com bines r e v e r s i b l y w ith oxygen to form th e b r i g h t re d oxym yoglobin (W a tts, 1 9 5 4 ). I n t h i s compound th e heme ( ir o n ) rem ain s i n th e f e r r o u s (F e++) form . Two ty p e s o f o x i d a t i v e ch an g es may be r e s p o n s ib le f o r th e abnorm al brown d i s c o l o r a t i o n o f m eat (W a tts, 1 9 5 4 ). One in v o lv e s th e o x id a tio n o f th e f e r r o u s ir o n i n th e heme compound to th e f e r r i c c o n d itio n , th e second i s a d i r e c t a t t a c k by oxygen on th e p o rp h y rin r i n g . The m ost commonly e n c o u n te re d ty p e o f -1 3 - d i s c o l o r a t i o n i s t h a t o f th e Nmet'1 pigm ent form ed by o x id a tio n o f th e i r o n i n th e heme to t h e f e r r i c (Fe+++) s t a t e , known a s m etm yoglobin. H e iss and H o h ler (1933) s t a t e d t h a t c o lo r ch an g es i n m eat d u rin g s to r a g e may o r i g i n a t e i n t h r e e w ays: 1. The o x id a tio n o f re d m yoglobin to brown metmyoglobin* 2* The l o s s o f m o is tu re from t h e m eat s u r f a c e w ith c o n seq u en t i n ­ c r e a s e i n c o n c e n tr a tio n o f th e c o lo re d c o n s ti t u e n t s a t th e s u rfa c e * 3* The d i s i n t e g r a d a t i o n o f th e g lo b in components* Brooks (1929, 1930, 1931) s t a t e d t h a t th e pigm ent o f m uscular t i s s u e , m y o g lo b in, i s p r e s e n t a t th e s u r f a c e a s oxym yoglobin, w hich can change g r a d u a lly d u rin g c o ld s to r a g e to m etm yoglobin. W in ter (1952) s ta t e d t h a t m eat may d a rk e n due to o x id a tiv e r e a c t i o n s w ith th e r e d c o lo re d p ig m e n ts. F a c to r s I n f lu e n c in g th e C olor Changes o f F ro zen Meat 1* Oxygen P r e s s u r e and P e n e tr a tio n N e i l l (1925) h as shown t h a t th e r e was no e v id en ce t h a t m ethem oglobin was form ed i n th e co m p lete ab sen ce o f o^Qrgen s in c e i n t h i s c o n d itio n t h e r e w ere no o x id iz in g a g e n ts form ed to o x id iz e hem oglobin to m ethem oglobin. B rooks (1929) a l s o showed t h a t when hem oglobin was s to r e d i n p u re n it r o g e n s to r a g e t h e r e was no fo rm a tio n o f m ethem oglobin. From t h i s work i t was a p p a r e n t t h a t oxygen was n e c e s s a r y f o r th e fo rm a tio n o f m ethem oglobin, t h e d ark c o lo re d pigm ent o f m eat. R o b e rtso n (1950) s ta t e d t h a t s in c e d i s c o l o r a t i o n i s a c t u a l l y an o x id a tiv e r e a c t i o n , th e e lim in a tio n o f a i r c o n tro ls d is c o lo ra tio n . He s t a t e d t h a t low oxygen tra n s m is s io n r a t e f ilm i s v e r y e s s e n t i a l to in c r e a s e f r o z e n m eat q u a l i t i e s . -1 4 - He a ls o s t a t e d t h a t one o f t h e l i m i t i n g f a c t o r s i n meat f r e e z e r s to r a g e l i f e i s to be found i n th e d e g re e o f oxygen p r o t e c t i o n o f f e r e d by th e p ack ag in g m a t e r i a l . The r e l a t i o n b etw een oxygen p r e s s u r e and th e r a t e o f m ethem oglobin fo rm a tio n was r e s p o n s i b le f o r th e r a p id d i s c o l o r a t i o n o f t i s s u e s to r e d a t 32°F i n g a s e s c o n ta in in g a sm a ll amount o f oxygen a c c o rd in g to Brooks (1 9 2 9 ). He found t h a t t i s s u e had a sm a ll oxygen s u f f i c i e n t tim e , a u p ta k e so t h a t , g iv e n s te a d y s t a t e ” was re a c h e d where th e d e p th o f oxygen p e n e t r a t i o n was d e te rm in e d by th e r a t e o f d i f f u s io n o f oxygen in t o th e t i s s u e s and th e oxygen consum ption o f th e t i s s u e . He showed t h a t th e d e p th o f oxygen p e n e t r a t i o n was d eterm in ed by th e oxygen p r e s s u r e i n a t ­ m ospheres a t th e s u r f a c e o f th e t i s s u e , th e d i f f u s io n c o e f f i c i e n t o f oxygen th ro u g h th e t i s s u e , and th e oxygen u p ta k e o f th e t i s s u e . Brooks (1935) fo u n d t h a t th e d e p th o f oxygen p e n e t r a t i o n showed a slow in c r e a s e w ith tim e , and a r i s e i n te m p e ra tu re d e c re a se d th e d e p th . He found t h a t th e d e p th o f oxygen p e n e t r a t i o n v a r ie d from 2 to 5 mm and t h a t th e d e p th o f p en e­ t r a t i o n was p r o p o r t i o n a l to t h e sq u are r o o t o f th e oxygen p r e s s u r e i n a t ­ m o sp h eres. Brooks (1929) gave th e f o llo w in g fo rm u la f o r f in d in g th e d e p th o f oxygen p e n e t r a t i o n : w here d = d e p th o f oxygen p e n e tr a ti o n ; c0 th e p r e s s u r e o f oxygen a t th e s u r f a c e o f th e t i s s u e and D and A a r e r e s p e c t i v e l y th e c o e f f i c i e n t s o f i t s d i f f u s i o n th ro u g h th e t i s s u e and consum ption. T h e re fo re , th e d is s o lv e d oxygen was p r e s e n t o n ly i n a s u p e r f i c i a l la y e r a few mm t h i c k . t i o n was c o n fin e d to th e s u p e r f i c i a l l a y e r . -1 5 - D is c o lo r a ­ F re e z in g and thaw ing th e t i s s u e had no s i g n i f i c a n t e f f e c t on oxygen p e n e t r a t i o n , b u t d id a c c e l e r a t e m et­ hem oglobin f o rm a tio n i n th e r e g io n o f oxygen p e n e t r a t i o n . 2. P ack ag in g M ethods and M a te r ia ls R o b e rtso n (1950) s t a t e d t h a t v i s i b i l i t y and t i g h t n e s s o f wrap a r e a n e c e s s a r y re q u ire m e n t f o r f r o z e n m eat. a p ack ag e m a t e r i a l a s f o llo w s : He gave t h e e s s e n t i a l f e a t u r e s o f low oxygen tr a n s m is s io n r a t e and low m o is tu re vapor tr a n s m is s io n to p re v e n t d e h y d ra tio n . He s t a t e d t h a t a p a c k a g in g m a t e r i a l w ith low m o is tu re vapor tra n s m is s io n r a t e i s e s s e n t i a l b e c a u s e m eat bloom i s an e f f e c t o f s u r f a c e m o is tu re o v e r re d m eat c o l o r . He f u r t h e r m en tio n ed t h a t v a r io u s c o lo r e f f e c t s can be o b se rv e d a s s u r f a c e d e h y d r a tio n p ro c e e d s on t h e packaged p ro d u c t i n s to r a g e . A g ra y o r d a rk c o lo r can be n o tic e d i n th e l a t e r s ta g e s o f d e h y d ra tio n . O rd in a rily , t h i s l a t e s ta g e o f d e h y d r a tio n i s known a s “f r e e z e r b u rn ” . R o b e rtso n (1950) s t a t e d t h a t th e w rapping o f th e p ro d u c t sh ould be so w e ll done t h a t i t i s f r e e o f a i r p o c k e ts , w hich ca u se th e l o s s o f v i s i b i l i t y when m o is tu re co n d en ses i n th e c a v i t y form ing a show o r f r o s t . Weisman (1947) s t a t e d t h a t by w rapping th e p ro d u c t t i g h t l y i n a m a t e r i a l p o s s e s s in g a low m o is tu re v ap o r tr a n s m is s io n r a t e , t h e ten d en cy f o r m o is tu re to t r a v e l o utw ard i s m inim ized. A ir p o c k e ts m ust b e av o id ed a s much a s p o s s i b l e b ec au se where a i r i s p r e s e n t r i th in a p ack ag e, t h e r e i s a c e r t a i n amount o f m o is tu r e l o s s r e s u l t i n g i n f r o s t f o rm a tio n on th e i n n e r s u r f a c e o f “the p a c k a g e . C lose ad h eren ce o f th e p ro d u c t a ls o p r e ­ v e n ts h arm fu l o x id a tiv e ch an g es. He f u r t h e r s t a t e d t h a t p ro p e r p ack ag in g o f f r o z e n m eats i s a ls o o f m a te r ia l a id i n re d u c in g “c a v ity ic e " fo rm a tio n w ith in a p a c k a g e . “C a v ity i c e “ i s a term co in ed by S a y le s (1946) t o d e s ig ­ n a te t h e fo rm a tio n o f i c e i n th e a i r sp aces i n s i d e a p a c k a g e . -1 6 - T h e re f o re , by u s e o f c e r t a i n p a c k a g in g m a t e r ia l s w hich p ro v id e i n s u l a t i o n and th u s r e d u c e te m p e r a tu re g r a d i e n t s betw een th e p ro d u c t and th e p ack a g in g s u r ­ f a c e , th e te n d e n c y f o r c a v i t y i c e to form i s le s s e n e d . Moran (1935) s t a t e d t h a t sim p le d e s ic c a t i o n , p a r t i c u l a r l y o f f r o z e n m e a ts , l e a d s to a p p a r e n t d i s c o l o r a t i o n . L a v e rs (1948) s t a t e d t h a t u s in g an oxygen im perm eable w rap, th e su p p ly o f in oxygen i s c u t o f f and th e r a t e o f o x id a tio n to m ethem oglobin, i . e . , th e r a t e o f d i s c o l o r a t i o n , i s g r e a tly in c re a s e d . M ethem oglobin i s formed r a p i d l y when th e p r e s s u r e o f oxygen aro u n d th e meat i s red u ced by th e p ack ag in g m a t e r ia l. R o b e rtso n (1950) s t a t e d t h a t f r e s h m eat c o lo r and c o lo r s t a b i l i t y w i l l som etim es change a t d i f f e r e n t r a t e s i n d i f f e r e n t m a t e r i a ls and t h a t c o lo r may be r e a d i l y l o s t i n t h e wrapped p ackage i f th e package i s n o t s e n t d i r e c t l y to th e f r e e z e r . 3. M ethods o f F re e z in g T h e re a r e s e v e r a l m ethods o f f r e e z in g m eat. Among th e s e a r e : 1. F r e e z in g i n low te m p e ra tu re room s i n s t i l l a i r . 2. F re e z in g i n low te m p e ra tu re rooms i n an a i r b l a s t . 3. F re e z in g on c o i l s . 4. P la te fre e z in g . 5. F re e z in g i n l i q u i d a i r , b r in e , e t c . R o b e rtso n (1950) h a s d is c u s s e d each one o f th e s e m ethods. He s ta t e d t h a t s t i l l a i r f r e e z i n g r e s u l t e d i n a v e ry d ark c o lo re d meat s u r f a c e . T h is was a s i t u a t i o n i n w hich th e s u r f a c e d id n o t f r a c t u r e , b u t th e r a t e o f f r e e z i n g was so slow t h a t a l l o f th e o r i g i n a l r e d meat c o lo r was l o s t . Once th e p ro d u c t i s s a t i s f a c t o r i l y f r o z e n and h e ld a t s u b -z e ro te m p e r a tu re s , -1 7 - th e c o lo r c h an g es a r e slow . He a ls o s t a t e d t h a t p l a t e f r e e z i n g a t -5 0 °F a lth o u g h v e ry r a p i d , r e s u l t e d in alm o st com plete l o s s o f th e s u r f a c e c o lo r and a p p e a ra n c e . The s u r f a c e was d e s c rib e d a s h av in g been f r e e z e r b u rn e d , b u t t h a t t h i s c h a r a c t e r i s t i c was due t o t h e f r a c t u r e o f th e f r o z e n s u r f a c e la y e r. He s t a t e d t h a t b l a s t f r e e z in g gave s im ila r r e s u l t s . He n o te d t h a t when s t i l l a i r was u sed f o r f r e e z in g a t 0 °F , th e meat was d a rk i n c o l o r . He co n clu d ed t h a t th e d a rk c o lo r i n m eat f r o z e n by s t i l l a i r was due to th e f a c t t h a t th e r a t e o f f r e e z i n g was so slow t h a t a l l o f th e o r i g i n a l m eat c o lo r was l o s t . J e n s e n (1 9 4 9 ), on th e o t h e r hand, r e p o r te d t h a t a te m p e ra tu re o f -1 0 °F o r lo w e r r e s u l t e d i n a s a t i s f a c t o r y c o lo r when f r e e z in g by th e b l a s t m ethod. Brooks (1 9 2 9 , 1930, 1931) r e p o r te d t h a t b ecau se o f th e u n s ig h t ly a p p e a ra n c e o f t h e thaw ed s u r f a c e due t o th e e f f e c t o f f r e e z in g i n c o n c e n tr a te d s a l t s o l u t i o n , t h i s ty p e o f f r e e z i n g h as n o t been ad o p ted co m m e rc ia lly . l i e r 's C ol­ (1956) s t a t e d t h a t f r e e z i n g m eats i n l i q u i d n itr o g e n a t te m p e ra tu re s a s low a s -3 2 0 °F showed b e t t e r c o lo r th a n th o s e f r o z e n a t -2 0 °F . 4. E f f e c t o f Time, T em perature and R e la tiv e H um idity A t 14°F B rooks (1937) fo u nd no v i s i b l e d i s c o l o r a t i o n of le a n m eat s to r e d f o r s ix t e e n w eeks. At 2 9 .5 °F t h e r e was no d i s c o l o r a t i o n owing to th e f o rm a tio n o f m ethem oglobin u n t i l 40-50 days from k i l l i n g . s to r e d s a n p le s a t te m p e r a tu re s ra n g in g from 1 0 .4 °F t o -1 1 .2 ° F . Mangel (1951) She found t h a t m ethem oglobin fo rm a tio n was slo w er i n sam ples s to r e d a t th e h ig h e r te m p e r a tu re th a n i n sam ples s to r e d a t th e lo w er te m p e ra tu re . w ork (1947) would i n d i c a t e th e o p p o s ite . R am sbottom 's He s to r e d f r e s h b e e f a t s i x d i f ­ f e r e n t te m p e r a tu re s ra n g in g fro m -2 0 °F to 26°F packaged i n DuPont 300 M .S.A .T. #87 c e llo p h a n e . The p ro d u c t s to r e d a t 26°F was d is c o lo r e d i n l e s s th a n -1 8 - t h i r t y d a y s , w h ereas th e p ro d u c t s to r e d a t -2 0 °F was s t i l l sc o re d good i n c o lo r and a p p e a ra n c e a f t e r one y e a r f s sto ra g e * He co n clu d ed t h a t th e lo w er t h e te m p e ra tu re o f s to r a g e , th e lo n g e r th e s to r a g e l i f e . T re s s le r and E v e rs (1947) s t a t e d t h a t f r o z e n meat changes i n c o lo r from th e re d to brown c o l o r a t a h ig h e r te m p e ra tu re o f s to r a g e . At 29°F, d i s c o l o r a ­ t i o n o f b e e f was n o t i c e a b l e a f t e r e ig h t w eeks, w hereas a t 14°F t h e r e was no n o t i c e a b l e change i n c o lo r u n t i l a f t e r 12 weeks* Ramsbottom and Koonz (1941) d eterm in e d th e r e l a t i v e c o n c e n tr a tio n o f oxyhem oglobin and m ethem oglobin i n th e s u r f a c e o f t i s s u e s to r e d f o r one y e a r a t 10°F and -3 0 ° F . They p l o t t e d s p e c tr a c u rv e s from e x t r a c t s o f th e s u r f a c e t i s s u e from s p e c tro p h o to m e tric r e a d in g s . The c u rv e s f o r th e s te a k s s to r e d a t 10°F f o r one y e a r w ere q u i t e s im il a r to th e c u rv e f o r methemo­ g lo b in . The c u rv e s f o r s te a k s s to r e d a t -3 0 °F in d ic a te d a m ix tu re o f oxy­ hem oglobin and m ethem oglobin. T his in d ic a te d t h a t a g r e a t e r o x i d a tio n , and c o n s e q u e n tly , d a r k e r b e e f , o c c u rre d i n th e t i s s u e a t 1CK>F th a n a t -3 0 ° F . J e n se n (1949) s t a t e d t h a t f r e e z i n g sh ould be done a t a r a t e w hich gave m eat a b r i g h t c o lo r . A te m p e ra tu re o f -10°F o r lo w er r e s u l t e d i n a s a t i s ­ f a c t o r y c o lo r when f r e e z i n g by th e b l a s t f r e e z in g m ethod. He a g re e d w ith R o b e rtso n i n t h a t slo w ly f r o z e n m eats w ere d ark i n c o l o r . B rooks (1929) n o te d t h a t th e fo rm a tio n o f m ethem oglobin i n f r o z e n m eat was l e s s im p o rta n t ( u n le s s th e tim e o f s to r a g e was lo n g ) th a n th e l o s s o f c o lo r due to e x c e s s iv e d r y in g . He s a id t h a t c r y s t a l s o f i c e i n th e s u p e r­ f i c i a l l a y e r e v a p o r a te , and th e sm a ll b u lb s o f a i r l e f t b eh in d s c a t t e r th e in c id e n t l i g h t . -1 9 - R o b e rtso n (1950) d is c u s s e d th e in f lu e n c e o f te m p e ra tu re on th e con­ d e n s a tio n o f m o is tu re i n th e c a v i t i e s o f m eat. He s t a t e d t h a t a i r a t 60°F c o n t a i n s 7 7 .2 9 g r a i n s o f m o is tu re p e r pound o f a i r , w h ereas a t -1 0 °F th e a i r c o n ta in s 3.206 g r a i n s o f m o is tu re p e r pound o f a i r . He a ls o n o te d t h a t th e m o is tu re c o n te n t o f t h e e n tra p p e d a i r can f l u c t u a t e w ith changes i n th e s to r a g e te m p e r a tu re . Wiesman (1947) gave f u r t h e r e x p la n a tio n on th e s u b je c t o f " c a v i t y i c e 11 w hich i n t e r f e r e d w ith v i s i b i l i t y o f th e p ro ­ d u c t. When a p r o d u c t i s s to r e d under f l u c t u a t i n g te m p e r a tu re s , th e r e i s a c e r t a i n in c re m e n t o f th e t o t a l w a te r i n m eat w hich i s b e in g c o n tin u a lly thaw ed and f r o z e n . The p r e s e n c e o f " c a v ity i c e 11 i s an i n d i c a t i o n t h a t a c e r t a i n amount o f d e h y d ra tio n o f th e p ro d u c t h as ta k e n p la c e s in c e m ois­ t u r e i s n e c e s s a r y f o r t h e fo rm a tio n o f i c e . A ccording to him , w a te r moves from t h e c o n te n ts o f th e p ro d u c t to th e s id e w a lls o f t h e pack ag e e i t h e r by c o n v e c tio n c u r r e n t s e s ta b li s h e d becau se o f a d i f f e r e n c e i n th e tem p era­ t u r e b etw een th e a i r and th e c o ld e r s id e w a ll, o r b ecau se o f an a l t e r n a t e r i s e and f a l l i n te m p e r a tu re . D uring a f a l l in te m p e ra tu re and th e sub­ se q u e n t l o s s o f w a te r h o ld in g c a p a c ity of th e i c e , i c e w i l l be d e p o s ite d on t h e c o l d e s t s u r f a c e e x i s t i n g a t t h e tim e . I f th e c o ld e s t s u r f a c e i s t h e p ack ag e c o n t e n t s , i c e w i l l be d e p o s ite d on th e c o n te n ts , w hich i n e f f e c t means no c a v i t y ic e fo rm a tio n . When th e te m p e ra tu re in s i d e th e p ack ag e r i s e s , i t w i l l a b s o rb w a te r from th e food c o n te n t and any p r e v i ­ o u s ly e x i s t i n g " c a v i t y i c e " . I f th e r e i s no te m p e ra tu re change w ith in th e p a c k a g e , no f r o s t w i l l fo rm . T h is may be re g a rd e d a s a "pumping a c t i o n " . A r e d u c t i o n i n te m p e ra tu re re d u c e s th e m o istu re -v a p o r i n th e a i r and c a u se s a p r e c i p i t a t i o n i n th e form o f i c e . An in c r e a s e i n te m p e ra tu re i n c r e a s e s -2 0 - t h e m o is tu r e -v a p o r c a p a c ity o f th e a tm o sp h ere, th u s c a u s in g a flo w o f th e m o is tu r e -v a p o r from th e p ro d u c t in to s u rro u n d in g atm osphere r e s u l t i n g i n d e t e r i o r a t i o n and f r e e z e r burn* 5* E f f e c t o f B io l o g i c a l A gents V o e g e li (1952) and B u tle r (1953) have summarized th e s tu d i e s o f th e w o rk e rs who s tu d ie d th e e f f e c t o f b i o l o g i c a l a g e n ts on th e c o lo r of f r e s h meat* V o eg e li (1952) m entioned t h a t th e s e w o rk ers found t h a t Pneum ococci re d u c e d m ethem oglobin to hem oglobin i n com plete ab se n c e o f oxygen and t h a t a n a e ro b ic b a c i l l i have th e a b i l i t y to o x i d i ze hem oglobin. B u tle r (1953) i n h i s w ork, found t h a t b a c t e r i a commonly found on meat c u t s cau sed d is c o lo ra tio n . The m ain e f f e c t , an i n c r e a s e i n t h e r a t e o f m etm yoglobin f o rm a tio n , was t h e g r e a t e s t d u rin g th e lo g a r ith m ic grow th p h a s e . A cco rd in g to Tanner (1 9 4 4 ), m ic r o b ia l developm ent was m arkedly r e ­ t a r d e d b u t n o t e n t i r e l y e lim in a te d by fre e z in g * S u lz b a c h e r (1950) s t a t e d t h a t th e p o p u l a r i t y o f f r o z e n food d u rin g th e p a s t two d ecad es h as o c c a ­ s io n e d c o n s id e r a b le i n t e r e s t i n th e grow th and s u r v i v a l o f m icro o rg an ism s d u rin g f r e e z i n g and f r o z e n s to ra g e * H aines (1931) re c o g n iz e d t h a t th e g ro w th o f Pseudomonas sp a t s u b - f r e e z in g te m p e ra tu re s was l i k e l y to p la y a p a r t i n m eat s p o ila g e * 6. E f f e c t o f S to ra g e I n D if f e r e n t A tm ospheres M angel (1951) s to r e d sam ples u n d er atm o sp h eres o f n i tr o g e n , oxygen, and c a rb o n d io x id e , w ith a i r as th e c o n t r o l. She found no s i g n i f i c a n t d i f f e r e n c e , b u t th e m ethem oglobin fo rm a tio n te n d e d to be slo w er when th e t i s s u e was s to r e d u n d er oxygen, th a n u n d er n it r o g e n , carb o n d io x id e o r a i r 9 -2 1 - R o b e rtso n (1950) s t a t e d t h a t n itr o g e n may be used to d i s p l a c e t h e a i r i n a p ack ag e and th e r e b y p r e v e n t d is c o lo r a tio n * Brooks (1935) n o te d t h a t th e r a t e o f o x id a tio n o f hem oglobin i n m uscle was n o t a f f e c t e d to a s i g n i f i c a n t e x t e n t by c o n c e n tr a tio n s o f carb o n d io x id e below 20%. Hence, i f o th e r c o n d itio n s o f s to r a g e a r e th e same, th e c o lo r change o f meat i n a i r and i n a i r c o n ta in in g 20% carb o n d io x id e sh ould be th e same* R i k e r t (1952) f lu s h e d packaged sam ples w ith carbon d io x id e and n i t r o ­ gen b e f o r e e v a c u a tin g . T h is r e s u l t e d i n l e s s i n i t i a l d a rk e n in g th a n t h a t w hich o c c u rre d i n sam ples e v a c u a te d w ith o u t f l u s h i n g . He a ls o s to r e d sam ples a t a tm o sp h e ric p r e s s u r e i n carbon d io x id e and n it r o g e n . T h is had a d e t r im e n t a l e f f e c t on th e to p s u r f a c e c o lo r b u t improved th e b o tto m c o lo r when com pared w ith sam ples s to r e d i n a i r . E x p e rim e n ts co n d u cted by th e a u th o r (1955) in d ic a te d t h a t r e l a t i v e l y s h o r t e x p o su re o f m eat to an atm osphere o f 40% o r l e s s carb o n monoxide gave e x c e l l e n t c o lo r s t a b i l i t y in f r o z e n s to r a g e f o r p e r io d s o f s i x m onths o r lo n g e r. 7. E f f e c t o f L ig h t D is c o lo r a tio n s c au sed by ex p o su re to l i g h t become a p a r t i c u l a r l y s e r i o u s problem b ecau se o f modern m erch an d izin g m ethods w hich r e q u i r e ex p o su re o f r e t a i l c u t s i n l i g h t e d d is p la y c a s e s . A re v ie w o f t h e l i t e r a t u r e re v e a le d v e ry lim ite d in fo rm a tio n con­ c e rn in g th e e f f e c t o f l i g h t on p rep ack ag ed f r o z e n meat packaged i n a t r a n s p a r e n t w ra p p e r. -2 2 - Nauman (1957) s t a t e d t h a t s t a b i l i t y o f c o lo r o f f r o z e n b e e f vacuum p ack ed i n f l e x i b l e t r a n s p a r e n t f il m under 20-50 f o o t- c a n d le s o f i llu m in a ­ t i o n was r e l a t e d to le n g t h o f d ark s to r a g e , f o o t- c a n d le h o u rs o f i llu m in ­ a t i o n and te m p e r a tu re . He s to r e d sam ples i n th e d ark a t 0°F f o r 0 , 1 , 2 and 4 weeks p r i o r to illu m in a te d d i s p l a y . C ured, smoked and t a b l e re a d y m eats when exposed to l i g h t become “f a d e d 11 o r d i s c o l o r e d . T here have b een s e v e r a l s tu d ie s conducted to s tu d y th e c a u s e s o f t h i s ty p e o f d i s c o l o r a t i o n ( P r a c e ju s , 1949; A rc h e r, 1950; T a y lo r , 1950; Ramsbottom, 1951; Kampschmidt, 1955 and Hockman, 1 9 5 6 ). These s t u d i e s w ere co n d u cted i n o r d e r to b e t t e r u n d e rsta n d i t s r e l a t i o n ­ s h ip to r a d i a n t f l u x d e n s ity ( o r illu m in a tio n ) s p e c t r a l d i s t r i b u t i o n , and tim e o f e x p o s u re . I n some c a s e s o th e r v a r i a b l e s n o t d i r e c t l y r e l a t e d to r a d i a n t e n e rg y , su ch a s te m p e r a tu re , h u m id ity , w rapping m a t e r i a l s , e t c . , w ere a l s o c o n s id e re d . I t may be w o rth w h ile to summarize th e r e s u l t s o f th e v a r io u s t e s t s t h a t w ere conducted by th e above i n v e s ti g a to r s * 1. When te m p e ra tu re and o t h e r f a c t o r s a r e h e ld c o n s ta n t, r a t e o f f a d in g w i l l be t h e same u n d er e i t h e r in c a n d e s c e n t o r any o f s e v e r a l w h ite f lu o r e s c e n t lam ps, p ro v id in g il l u m i n a ti o n i s th e same f o r b o th . 2. The d e g re e o f d i s c o l o r a t i o n o f a p a r t i c u l a r p ro c e ss e d m eat saaqple i s a f u n c t io n o f e x p o su re in f o o t- c a n d le h o u rs . The r e c i p r o c i t y law was found to a p p ly ov er a ra n g e o f 20-200 f o o t- c a n d le s , f o r b aco n , b o lo g n a, and s l i c e d ham. ra n g e w ere n o t r e p o r te d . -2 3 - I llu m in a tio n l e v e l s o u ts id e t h i s 3. The m a in ta in e d te m p e ra tu re o f th e m eats may have a s i g n i f i c a n t e f f e c t on t h e i r s u s c e p t i b i l i t y to fa d in g * In a s e r ie s o f t e s t s by A rch er (1 9 5 0 ), r a i s i n g th e te m p e ra tu re o f th e m eat from 34°F to 40°F r e s u l t e d i n an ap p ro x im a te 50% r e d u c tio n in th e ex p o su re f o r minimum p e r c e p t i b l e f a d in g . F re s h m e a ts , on th e o t h e r hand, a p p e a r to be r e l a t i v e l y u n a f f e c te d u n d e r n o rm al d i s p l a y c o n d itio n s o f l i g h t . K r a ft (1964) r e p o r te d t h a t th e i n t e n s i t y o f s o f t w h ite f l u o r e s c e n t l i g h t was u n im p o rta n t i n in f lu e n c in g th e c o u rs e o f d i s c o l o r a t i o n o f packaged f r e s h b e e f . M easurem ents o f sp e c ­ t r a l r e f l e c t a n c e and v i s i b l e c o lo r changes in d ic a te d t h a t u l t r a - v i o l e t l i g h t cau sed r a p i d o x id a tio n o f m yoglobin to produce marked d i s c o l o r a t i o n o f f r e s h b e e f e a r l y i n s to r a g e . Ramsbottom (1951) r e p o r te d t h a t d is p la y c a s e l i g h t i n g d oes n o t s i g n i f i c a n t l y d is c o lo r f r e s h meat w ith in th e u s u a l d i s p l a y p e r io d s up to 3 d a y s . Longer d is p la y p e r io d s may b r in g ab o u t d i s c o l o r a t i o n t h a t i s a f a c t o r o f m ic ro b ia l developm ent. V oegeli (19B2) n o te d t h a t th e i n t e n s i t i e s o f l i g h t em ployed, 20-215 f o o t- c a n d l e s , d id n o t a f f e c t th e r a t e o f c o lo r change o f unwrapped sam ples u n d e r com parable s to r a g e te m p e r a tu re s . S o u rces o f l i g h t t h a t in c r e a s e d t h e s to r a g e tem­ p e r a t u r e red u ce d th e s a le a b l e s to r a g e tim e o f b o th wrapped and unwrapped sam p les. -2 4 - PURPOSE OF STUDY A re v ie w o f th e l i t e r a t u r e r e v e a l s some in fo rm a tio n c o n c e rn in g th e e f f e c t o f v a r io u s c o n d itio n s on d i s c o l o r a t i o n i n prep ack ag ed f r o z e n m eat, b u t t h e r e i s l i t t l e in fo r m a tio n co n c e rn in g th e c h a r a c te r o f t h i s d i s ­ c o lo r a tio n . The m ain p u rp o se o f t h i s i n v e s t i g a t i o n was to a tte m p t to c h a r a c t e r iz e t h e c h e m ic a l s t a t e o f m yoglobin a s a f f e c te d by v a r io u s s to r a g e c o n d itio n s * One m ajor c a u s e o f d i s c o l o r a t i o n i n prepackaged f r o z e n m eats packaged i n a t r a n s p a r e n t p ackage i s t h a t o f l i g h t . T h is e f f e c t h a s been s u s p e c te d by s e v e r a l i n v e s t i g a t o r s , b u t su p p o rtin g ev id en ce a s to what p r o p e r ty o f l i g h t c a u s e s th e d i s c o l o r a t i o n h as been in c o m p le te ly p r e s e n te d o r e n t i r e l y a b s e n t. A c c o rd in g ly , e x p e rim e n ts w ere d esig n e d and conducted to stu d y w hat p r o p e r ty o f l i g h t c a u s e s t h i s d i s c o l o r a t i o n and to c h a r a c t e r i z e th e ch e m ic a l s t a t e o f m yoglobin a s a f f e c te d by lig h t* -2 5 - EXPERIMENTAL PROCEDURE I* S am pling P ro c e d u re and Methods o f F re e z in g The L o n g issim u s d o r s i m uscle from U .S. Good and C hoice g ra d e b e e f r i b s w ere u se d th ro u g h o u t t h i s s tu d y . B o n ele ss r i b s te a k s a p p ro x im a te ly one in c h t h i c k were c u t from t h e w h o le s a le r i b c u t . A l l s te a k s w ere allow ed to bloom f o r 30 m in u tes and th e n a 3mm s l i c e was removed f o r sp ectro p h o to m e tric e s tim a tio n o f metmyo­ g lo b in . The s te a k s w ere th e n p la c e d i n a -20°F f r e e z e r to h a rd en f o r a p p ro x im a te ly one h o u r. T h is was done to f a c i l i t a t e p a c k a g in g . A f te r rem oval from th e f r e e z e r , th e s te a k s w ere p la c e d i n Cry-0-W rap p la s tic bags. The b ag s w ere vacuum ized, c lo s e d w ith a Cry-0-W rap c l i p , d ip p ed i n t o b o i l i n g w a te r w h ich red u ced th e s iz e o f th e bag a p p ro x im a te ly o n e - t h i r d , th u s g iv in g th e s te a k s a t i g h t w rap. r e t u r n e d to a -2 0 °F f r e e z e r f o r 24 h o u rs . The s te a k s w ere th e n A f te r f r e e z in g , m easurem ent o f s u r f a c e c o lo r was made by u s e o f M unsell s p in n in g d is k s i n th e f r e e z e r * T h is method w i l l be d is c u s s e d u n d er c o lo r m easurem ents. A f te r s u r f a c e c o lo r m easurem ents were made, th e s te a k s w ere removed fro m th e f r e e z e r and s u b je c te d to th e v a r io u s s to r a g e c o n d itio n s o f t h i s in v e s tig a tio n . T hese s to r a g e c o n d itio n s w i l l be d is c u s s e d i n more d e t a i l u n d e r r e s u l t s and d i s c u s s io n . II. S to ra g e A. T em perature The p rep ack ag ed f r o z e n s te a k s used i n th e v a r io u s s tu d i e s w ere s to r e d i n a s e l f - s e r v i c e c a s e o r i n a c i r c u l a t i n g co ld a i r w a lk -in ty p e f r e e z e r -2 6 - e x c e p t i n th e stu d y c o n c e rn in g th e e f f e c t o f r e p e a te d f r e e z i n g and thaw ing on m etm yoglobin fo rm a tio n * The steal?s used i n t h i s s tu d y w ere s to r e d i n a -20°F f r e e z e r # A S h e re r s e l f - s e r v i c e f r o z e n food c a se was u sed to s to r e th o s e s te a k s o b s e rv e d u n d e r s e l f - s e r v i c e c o n d itio n s * The te m p e ra tu re o f th e c a s e and f r e e z e r w ere m easured by th e u se o f a Foxboro f i l l e d system r e c o r d in g therm om eter* R eco rd s o b ta in e d were a s shown i n F ig u re s 5 and 6* A Honey­ w e ll r e c o r d in g tw e lv e p o in t p o te n tio m e te r was u sed to m easure te m p e ra tu re v a r i a t i o n s i n v a r io u s p o in ts o f th e s e l f - s e r v i c e case# B. R ep eated F re e z in g and Thawing Twelve s te a k s w ere p ackaged i n Cry-0-W rap p l a s t i c b ags and tw e lv e s te a k s w ere packaged i n aluminum f o i l . f o u r hours* These s te a k s w ere f r o z e n tw e n ty - S te a k #1 from each ty p e o f wrap was ta k e n from th e f r e e z e r and allo w ed to thaw f o r two h o u rs to f a c i l i t a t e s l i c i n g f o r e x t r a c t i o n p u rp o s e s . A f te r th e w rap p ers were rem oved, s u rf a c e c o lo r m easurem ents w ere made by th e u se o f M u n sell s p in n in g d is k s and e s tim a tio n o f metmyo­ g lo b in by th e u s e o f th e s p e c tro p h o to m e te r. S te a k s #2 th ro u g h #11 were allo w e d to thaw f o r tw e n ty -fo u r h o u rs and th e n r e f r o z e n f o r tw e n ty -fo u r h o u rs. S te a k s #2 w ere removed a f t e r thaw ing and r e f r o z e n o n ce. S te a k s #3 removed a f t e r thaw ing and r e f r o z e n tw ic e , and so f o r t h u n t i l S te a k s #11 w ere thawed and r e f r o z e n te n tim e s . pH and a b s o rp tio n s p e c tr a d e te rm in a ­ t i o n s w ere made on a l l ste a k s# -2 7 - 99 F ig u re 5* T em perature o f S e lf - S e r v ic e F ro zen Food D isp la y Case -2 8 - V t HMu „ UNIFORM ^ O ry °* 0 , M ASS; $fl99f6I 0 “0 ««W I. F ig u re 6 . T em perature o f 0°F F re e z e r -2 9 - C* E f f e c t o f L ig h t S te a k s s to r e d i n th e s e l f - s e r v i c e f r o z e n food c a s e u n d er th e i n f l u ­ en ce o f l i g h t w ere k e p t u n d er f lu o r e s c e n t lam ps d e l i v e r i n g 56 f o o t- c a n d l e s o f illu m in a tio n . V a rio u s c o lo r e d f i l t e r s w ere u sed i n th e stu d y con­ c e r n in g th e a t t r i b u t e o f l i g h t t h a t may be r e s p o n s ib le f o r c o lo r d e g ra d a ­ tio n , S te a k s s to r e d i n th e 0°F f r e e z e r u n d er th e in f lu e n c e o f l i g h t w ere k e p t u n d e r f l u o r e s c e n t and in c a n d e s c e n t lam ps d e l i v e r i n g 56 f o o t- c a n d l e s o f i l l u m i n a t i o n , e x c e p t i n one s tu d y where th e s te a k s w ere k e p t u n d er v a r i o u s c o lo r e d f l u o r e s c e n t lam ps d e l i v e r in g 20 f o o t- c a n d le s o f i l lu m i n ­ a tio n , III, C o lo r M easurem ent D e ta ile d i n s t r u c t i o n s w ere g iv e n by V o eg eli (1952) on th e a p p l i c a t i o n o f d i s k c o lo r im e tr y f o r th e m easurem ent o f th e s u r f a c e c o lo r o f m eats by u se o f M u n sell s p in n in g d isk s* The s ta n d a rd c o lo r em ployed f o r c a l c u l a t i o n o f th e in d e x o f f a d in g ( I ) by th e fo rm u la o f N ic k e rso n (1 9 4 6 ), as a p p lie d by V o eg eli (1952) was 7 ,0 Red i n Hue, 4 ,0 i n V alu e, and 8 .0 i n Chroma. The s e le c te d s ta n d a rd f o r t h e p l o t t i n g o f c o lo r r e a d in g s o f f r o z e n m eat was th e c o lo r o f some v e ry b r i g h t s te a k s o b ta in e d by B u tle r (1953) fo llo w in g tr e a tm e n t w ith oxygen u n d er p r e s s u r e . By u s in g th e N ick erso n (1946) fo rm u la , i t was p o s s i b l e to f i n d t h e p o s i t i o n o f su b seq u en t sample r e a d in g s i n r e l a t i o n to t h e s ta n d a r d . These p o s i t i o n s w ere p l o t t e d a g a in s t tim e to show th e d i s c o l o r a t i o n o f p rep ack ag ed f r o z e n meat d u rin g s to r a g e . E s tim a tio n o f th e p e r c e n t m etm yoglobin was e s s e n t i a l l y a s a p p lie d by M angel (1951) and B u tle r (1 9 5 3 ). A s l i c e th r e e mm i n th ic k n e s s was removed -3 0 - w ith a H obart Model 300 s l i c i n g m ach in e. t o th e n e a r e s t 1 /1 0 gram . The s l i c e was w eighed on a b a la n c e A f t e r w e ig h in g , th e s l i c e was t r a n s f e r r e d to a c h i l l e d W aring B len d o r j a r and d i s t i l l e d w a te r a t 34°F was added to g iv e a d i l u t i o n o f 1 to 8 , w h ich gave a s o l u t i o n o f a p p ro x im a te ly 0 ,0 2 to 0 ,0 3 m illim o la r c o n c e n t r a t i o n . S o lu tio n s o f such c o n c e n tr a tio n s had o p t i c a l d e n s i t i e s f a l l i n g on a d e s i r a b l e a r e a o f th e o p t i c a l d e n s ity sc a le * E x tr a c te d m yoglobin i s somewhat u n s ta b l e , and m etm yoglobin may i n c r e a s e o r d e c r e a s e d ep en d in g on th e c o n d itio n s u n d er w hich i t i s h an d led b e f o r e th e o p t i c a l d e n s i t i e s a r e ta k e n . M angel (1951) s t a t e d t h a t th e p e r c e n t o f m etm yoglobin in c r e a s e s w ith tim e . At any r a t e , i t i s v e r y n e c e s s a r y to s ta n d a r d iz e th e e x t r a c t i o n p r o c e d u re . I n th e s e s t u d i e s , o p t i c a l den ­ s i t y r e a d in g s w ere ta k e n w ith in a p p ro x im a te ly one h o u r fro m th e tim e o f e x t r a c t i o n o f th e p ig m e n t. O p tic a l d e n s it y was m easured i n a Beckman Model DU s p e c tro p h o to m e te r a t wave l e n g t h s o f 544 and 582 m illim ic r o n s . The t o t a l pigm ent concen­ t r a t i o n was o b ta in e d by c o n v e rs io n o f th e p ig m en ts to th e CN d e r i v a t i v e by ad d in g a d ro p o f 2% s o l u t i o n o f p o ta s s iu m f e r r i c y a n i d e and a drop o f 0.5% p o ta s s iu m c y a n id e to each c u b it a f t e r r e a d in g s were o b ta in e d . The r e s u l t a n t m etm yoglobin c y a n id e d e r i v a t i v e was m easured a t 540 m illim ic r o n s and th e m illim o la r e x t i n c t i o n c o e f f i c i e n t o f 1 1 .3 g iv e n by Bowsn (1949) f o r m etm yoglobin c y a n id e was u sed to c a l c u l a t e th e c o n c e n tr a t io n . The c a l c u l a t i o n o f c o n c e n tr a tio n o f th e s o lu tio n whose o p t i c a l den­ s i t y was m easured was b ased on th e L am bert-B eer law a s g iv e n by Bowen (1 9 4 9 ). -3 1 - I°g-1Q Where I Q I d J0 I = d - ST c l =i n t e n s i t y o f i n c i d e n t l i g h t - i n t e n s i t y o f em ergent l i g h t « d e n s it y fro m s p e c tro p h o to m e te r = m o lar e x t i n c t i o n c o e f f i c i e n t c ■» m o lar c o n c e n tr a tio n 1 ■ l e n g t h o f l i g h t p a th th ro u g h th e s o lu ti o n i n cm(= 1 .0 f o r th e c e l l u s e d ) . c = d s: w here 1 = 1 .0 and f o r t h i s s tu d y c * d 1 1 .3 x 10* To e s tim a te t h e p e r c e n t m etm yoglobin, th e d i f f e r e n c e betw een th e e x t i n c t i o n c o e f f i c i e n t s o f oxym yoglobin and m etm yoglobin a t 544 and 582 m illim ic r o n s w ere ta k e n as maximum p o s s i b le change a t th e s e w a v e le n g th s . T hese f i g u r e s w ere 9 .6 a t 544 mu and 1 2 .1 a t 582 mu a s g iv e n by Bowen (1 9 4 9 ). At each w a v e le n g th , th e change due to m etm yoglobin was e q u a l to t h e 2 1 o f oxym yoglobin m inus t h a t o f th e sam ple. By d iv id in g th e f i g u r e o b ta in e d by th e t o t a l change i n 21 from oxym yoglobin and m etm yoglobin and m u ltip ly in g by 100, an e s tim a tio n o f th e p e r c e n t m etm yoglobin was o b ta in e d . The e s tim a tio n s o f th e p e r c e n t m etm yoglobin a t 544 mu and 582 mu w ere a v era g ed to o b ta in th e f i n a l e s tim a te o f th e p e r c e n t m etm yoglobin. -3 2 - % RESULTS AND DISCUSSION A* T e m p e ratu re T e m p eratu re h a s b e en found i n many s tu d i e s to have a marked e f f e c t on c o lo r d e g r a d a tio n i n f r o z e n m e a ts . (B ro o k s, 1937; M angel, 1951; Ramsbottom, 1947; T r e s s l e r an d E v e rs , 1947; and J e n s e n , 1 9 4 9 ). T h e re f o re , i t i s e s s e n ­ t i a l t h a t one have some in f o r m a tio n c o n c e rn in g th e e f f e c t o f te m p e ra tu re on c o l o r d e g r a d a tio n o f p rep ack ag ed f r o z e n m e a t. I n o r d e r to d e r iv e some i n ­ f o rm a tio n on c o lo r d e g r a d a tio n a s r e l a t e d t o te m p e r a tu r e , i t was d e c id e d to do t h i s p h a se o f th e s tu d y i n t h r e e p a r t s , nam ely, 1 . ) te m p e ra tu re v a r ­ i a t i o n i n th e s e l f - s e r v i c e c a s e ; 2 . ) te m p e ra tu re v a r i a t i o n i n th e s e l f s e r v i c e c a s e when lo a d e d to c a p a c ity and 3 . ) th e e f f e c t o f p re h a n d lin g c o n d itio n s and th e r a t e o f f r e e z i n g on i n i t i a l c o lo r d e g r a d a tio n . 1. T em p eratu re V a r ia tio n i n S e l f - S e r v i c e Case Therm ocouples w ere p la c e d i n s e v e r a l s te a k s i n t h r e e l o c a t i o n s a s f o llo w s : 1 . ) b o tto m o f s te a k n e x t to th e b o tto m o f th e c a s e ; 2 . ) c e n te r o f t h e s te a k and 3 . ) to p o f th e s t e a k . R e s u lts o f t h i s p h a se o f th e s tu d y may be r e p r e s e n te d i n F ig u re 7 on page 34, w hich shows th e arran g em en t o f th e s te a k s i n th e s e l f - s e r v i c e c a s e . The d iag ram r e p r e s e n t s an a e r i a l view o f th e s e l f - s e r v i c e c a s e . T em p eratu re f l u c t u a t i o n s w ith in th e s e l f - s e r v i c e c a s e i t s e l f v a r ie d fro m -£4»0°F to + 5 .0 °F d ep en d in g on th e s ta g e o f th e c y c lin g o f th e co m pressor f u r n i s h in g th e r e f r i g e r a n t . The te m p e ra tu re v a r ie d n in e s id e o f th e c a s e to th e o th e r s id e o f th e c a s e . d e g re e s from one I t was n o tic e d t h a t th e s u r f a c e o f th e s te a k s o c c a s io n a lly re a c h e d a te m p e ra tu re e q u a l to t h a t o f th e b o tto m o f th e s te a k . T h is may be e x p la in e d by th e f a c t t h a t t h e r e was -3 3 - r F ig u re 7 c o n d e n s a tio n o f m o is tu re from th e atm o sp h ere on th e s u r f a c e o f th e s te a k c a u s in g f u r t h e r c o o lin g o f th e p ro d u c t and th u s lo w e rin g th e s u r f a c e te m p e ra tu re o f t h e ste a k * T able I I I sum m arizes te m p e ra tu re v a r i a t i o n s i n t h e s e l f - s e r v i c e case* 2* T em p eratu re V a r ia tio n s i n Packaged F ro z e n S te a k s when S to re d i n a S e l f - S e r v i c e Case Loaded to C a p a c ity E ig h t s te a k s w ere used i n t h i s stu d y and a rra n g e d a s r e p r e s e n te d i n th e end view o f t h e s e l f - s e r v i c e c a s e a s shown i n F ig u re s 8 and 9* T herm ocouples w ere p la c e d i n each stea k * T em perature m easurem ents w ere made by th e u s e o f a tw elv e p o in t H oneyw ell r e c o r d in g p o te n tio m e te r . These s te a k s w ere s to r e d f o r a p e rio d o f te n days a f t e r w hich s u r f a c e c o lo r m easurem ents w ere made by th e u se o f M unsell s p in n in g d is k s and e s ti m a t i o n o f th e p e r c e n t raetm yoglobin by th e u se o f th e s p e c tro p h o to ­ m eter* -3 4 - F^H Load L ine a * * 18'* FI 1/ FjlD r u n * in C D c D “\ End View o f S e l f - S e r v ic e Case F ig u re 8 S te a k No* 7 T e m p eratu re 1 1 * 3 ^ to 2 4 ^ S te a k No,, T em p eratu re 8 7 . OOF to 1 0 .0 °F 5 7*0 °F to 9*5 ^ 6 11*0°F to 1 7 .0 °F 3 2 .0 ^ to 8*0^ 4 -3*0°F to - 1 . 0 ^ 1 10*0 ^ t o 2 .0 °F 2 -4*0°F to - 1 .0 ° F Figure; 9 R e s u lts o f t h i s s tu d y a r e summarized i n T ab le IV on page 38* They showed v a r i a t i o n i n te m p e ra tu re from one s id e o f th e c a s e to th e o t h e r s id e a s w e l l a s v a r i a t i o n i n te m p e ra tu re o f th e s te a k s s to r e d a t v a r io u s l e v e l s i n t h e s e l f - s e r v i c e case* I t was th o u g h t t h a t th o s e s te a k s s to r e d a t th e h ig h e r l e v e l s i n th e c a s e would have a h ig h e r p e rc e n ta g e o f m etm yoglobin th a n th o s e s te a k s s to r e d on th e b o tto m o f th e s e l f - s e r v i c e case* n o t b o rn e o u t i n t h i s study* T h is was The r e s u l t s o f t h i s s tu d y showed t h a t th e r e was n o t to o much d i f f e r e n c e i n th e p e r c e n t m etm yoglobin f o rm a tio n i n s te a k s s to r e d a t v a r io u s l e v e l s i n th e s e l f - s e r v i c e c a s e e x c e p t a t th e to p l e v e l w here t h e s te a k s w ere exposed to l i g h t and h ig h e r te m p e r a tu re s . P e rh a p s a stu d y sh o u ld have b een made t o see i f th e r e would be an i n c r e a s e i n metuqrog lo b in f o rm a tio n w ith o u t th e i n f lu e n c e o f l i g h t o r w hether i t was due to th e e f f e c t o f l i g h t . The s u r f a c e c o lo r o f th e s te a k s was r e l a t i v e l y good w here th e y w ere n o t exposed to l i g h t , b u t th e s te a k s on th e to p l e v e l b e­ came d is c o lo r e d i n ab o u t 2 -3 days* -3 6 - T a b le I I I , Summarized T e m p eratu re V a r ia tio n s In S e lf - S e r v ic e Case S te a k I Top o f s t e a k ..........................................-1 ° F to -2#8°Fo C e n te r o f s te a k ................................. - 3 ,5 ° F to B ottom o f s t e a k ........................... -5 .0 ° F , - 1 .0 ° F to - 3 ,0 ° F D u rin g D e f r o s tin g C y c l e .............................. + 3 .5 °F to +20°F Top o f s t e a k ..........................................- 1 .5 ° F to - 3 .0 ° F C e n te r o f s te a k • • • • • • » • to -2 ,0 ° F B ottom o f s te a k • • • • • • • • S te a k I I D u rin g D e f r o s tin g C y c l e 0°F - 0 ,5 ° F to + 2,5°F • + 4,0°F to + 19.5°F S te a k I I I Top l / 4 in c h o f s te a k • • • * . 0°F to +2°F B ottom l / 4 in c h o f s te a k • • . • 0°F to +5°F D u rin g D e f r o s tin g C ycle • * • • • • • + 5 .0 °F to + 14,5°F S te a k IV Top o f s te a k • • • • • • • • • • 0 .2 ° F to +8°F C e n te r o f s te a k * • « « • « + • + 1,0°F to +13°F B ottom o f s te a k • • • • • • • • + 4 ,0 °F to + 5 ,5 °F D uring D e f r o s tin g C ycle • • • • • • • -3 7 +30°F to +26°F T able IV S te a k No, P e r c e n t M etm yoglobin B e fo re and A f t e r S to ra g e A f te r B e fo re T em p eratu re V a r ia tio n In d ex o f F ad in g B efo re and A f te r S to ra g e A f te r B efo re 1 -1 0 °F to -2 °F 0*79 8.9 8 1 4 .0 1 4 .5 2 - 4°F to -1 ° F 0 .7 9 9 .6 8 2 0 .8 1 9 .0 3 + 2 .0 °F t o +8°F 0 .7 9 6 .6 5 2 0 .0 1 5 .7 4 -3 * 0 °F t© -1 °F 0 .7 9 9 .8 3 1 8 .9 1 1 .7 5 + 7 .OOF to +9.50F 0 .7 9 9 .9 5 1 7 .0 1 2 .7 6 +11«0°F to + 17,0°F 0 .7 9 1 0 .1 0 2 2 .8 1 7 .0 7 + 1 1 .5°F to +240F 0 .7 9 3 5.10 1 6 .5 2 2 .6 8 + 7 .OOF to +10° F 0 .7 9 4 7 .8 0 1 4 .7 2 8 .4 F ig u re 10 shows th e in d e x o f f a d in g o f th e s e e ig h t s te a k s* w h ich w ere n o t exposed to l i g h t d id n o t d i s c o l o r to any e x te n t* The s te a k s T here w ere some s te a k s t h a t even showed b e t t e r c o lo r th a n when p la c e d i n s to r a g e a s i n d i c a t e d by in d e x o f fa d in g * S te a k s #7 and #8 changed from 16*5 to 22*5; and fro m 14*7 to 28*4 u n i t s from S ta n d a rd , r e s p e c tiv e ly * 3* P re h a n d lin g C o n d itio n s and R ate o f F re e z in g In t h i s s tu d y , two s te a k s each w ere used and s u b je c te d to th e f o llo w in g t h r e e c o ld s to r a g e c o n d i t i o n s : 3 . ) f r e e z e r a t -2 0 ° F . 1*) c o o le r a t 34°Fj 2 ,) f r e e z e r a t 0°F and T herm ocouples were p la c e d i n each ste a k * f r e e z i n g was re c o rd e d by u se o f a r e c o rd in g p o te n tio m e te r . R ate o f M easurem ents o f s u r f a c e c o lo r w ere made e v e ry two o r th r e e h o u rs f o r tw elv e h o u rs and th e n l e f t o v e r n ig h t, w ith a f i n a l re a d in g made a t 24 o r 28 h o u rs by th e u se o f M u n sell s p in n in g d isk s * E s tim a tio n s o f m etm yoglobin w ere made b e f o r e and a f t e r tre a tm e n t* -3 8 - _____ Case when Loaded aS + -> o o +■» XJ Ch «h S e ° g o Ch +» Ch Ch o■> u = +■O > = = •-+ + -> ,Q O O ^ eg r-t oo eg CO co H in ^ «tfc M M X J4 Change of Prepackaged , . Fr ozen Storage Steaks Stored to Capacity Time in Days in S elf-S ervice 00 -Jo 50 In d ex o f F a d in g -U n its from S tan d ard 7 #0 S /4 .0 /8 o0 -3 9 - figure Co^or 10 CM a .) C o o le r T em p eratu re o f 34°F - The p u rp o se o f t h i s s tu d y was to see how lo n g i t w ould ta k e f o r th e c o lo r o f oxym yoglobin to be red u ced back to th e c o lo r o f re d u c e d m yoglobin when packaged i n a t r a n s p a r e n t oxygen im per­ m eable w ra p p e r. A f t e r ’’b lo o m in g ", th e s te a k s had a v e ry d e s i r a b l e re d c o lo r c h a r a c t e r i s t i c o f t h a t o f oxym yoglobin. D uring th e f i r s t hour t h a t th e s te a k s w ere i n th e Cry-O-W rap, th e r e was n o t to o much change in c o l o r . th e end o f two h o u rs th e s te a k s s t a r t e d to d i s c o l o r . At A t th e end o f 3, 4 , 5 and 6 h o u rs t h e r e was c o n s id e r a b le d i s c o l o r a t i o n o f th e s te a k s . At th e end o f sev en h o u rs , th e s te a k s w ere com parable i n c o lo r to th e s te a k s when f i r s t c u t. A t t h e end o f n in e h o u rs th e s te a k s showed g r e a t e r d i s c o l o r a t i o n th a n when f i r s t c u t . The c o n t r o l s te a k w hich was n o t w rapped, b u t l e f t exposed to a i r d is c o lo r e d a t ab o u t th e same r a t e , b u t d id n o t d i s c o l o r to th e same e x te n t a s th o s e s te a k s w rapped i n Cry-O-W rap. shown i n F ig u re 1 1 . S u rfa c e c o lo r ch an g es a r e T h is in d e x o f f a d in g g rap h shows v e ry w e ll th e change o f re d u c e d m yoglobin to th e r e d c o lo r o f oxym yoglobin and th e n th e change back to th e c o lo r o f red u ced m yoglobin when s to r e d i n an oxygen im perm eable w rap p in g m a t e r i a l . A f te r tw e n ty - e ig h t h o u rs , th e w rap p er was removed from one s te a k to see i f i t w ould "bloom" ( r e t u r n to th e r e d c o lo r o f oxyrayoglob in ) a g a in . I t was found t h a t when th e w rap p er was removed th e s te a k changed fro m 25 u n i t s fro m s ta n d a rd to 19 u n i t s from s ta n d a rd . t h e s te a k d id b r i g h t e n . T h is in d ic a te d t h a t P e r c e n t m etm yoglobin fo rm a tio n in c r e a s e d from 0% b e f o r e th e s te a k s w ere packaged to 19.86% and 16.85% a f t e r tw e n ty - e ig h t h o u rs o f s to ra g e . The s te a k w hich was n o t packaged and se rv ed a s a c o n t r o l changed fro m 0% m etm yoglobin to 5.63% m etm yoglobin. The l a r g e r p e r c e n t o f metmyo­ g lo b in i n th e f i r s t two s te a k s seems to be r e l a t e d to B rook’ s (1935) o b s e r ­ v a t i o n t h a t a s t h e s u r f a c e t e n s io n o f oxygen i s low ered to ab o u t 4-20mm Hg, t h a t t h e r e i s f a s t e r change o f red u ced m yoglobin to m etm yoglobin. -4 0 - 11* Degradation Storage of Prepackaged Frozen Steaks Condtions o -4 1 - By P reh an d lin g P c. P CO o 0*8/0*17 W 9L pjnepiTBq.s itroa^ svtun-Suxppj; jo xoptq; Time In Hours as Affected O o Figure Color 'O rH CO o o p CM LO b* ) R a te o f F r e e z in g - R o b e rtso n (1950) s t a t e d t h a t s t i l l a i r f r e e s i n g r e s u l t e d i n a v e ry d a rk c o lo r s u rfa c e * T his was a c o n d itio n i n w hich t h e s u r f a c e d id n o t f r a c t u r e , b u t th e r a t e o f f r e e z i n g was so slow t h a t a l l o f th e o r i g i n a l r e d m eat c o lo r was l o s t . J e n se n (1 9 4 9 ), on th e o t h e r h an d , r e p o r t e d t h a t a te m p e ra tu re o f -10°F o r low er r e s u l t e d i n a s a t i s f a c t o r y c o lo r when f r e e z i n g was done by th e b l a s t f r e e z i n g method* The r e s u l t s o f t h i s s tu d y showed t h a t s te a k s f r o z e n a t 0°F and a t -2 0 °F d is c o lo r e d a t a b o u t th e same r a t e a s in d ic a te d by th e in d e x o f f a d in g g ra p h i n F ig u r e 12* The i n i t i a l d i s c o l o r a t i o n o f th e s te a k i n th e 0°F f r e e z e r was more g r a d u a l th a n th o s e f r o z e n i n th e -20°F f r e e z e r * T h is sud­ den d i s c o l o r a t i o n i n th e -20°F f r e e z e r m ight be due to s u r f a c e f r a c t u r e su ch a s was r e p o r t e d by R o b e rtso n (i9 6 0 )* F ig u r e 13 shows t h e r a t e o f f r e e z in g o f one and o n e - f o u r th in c h s te a k s i n th e 0°F f r e e z e r and t h e -20°F f r e e z e r * I t sh o u ld be n o te d t h a t th e s te a k s f r o z e n a t 0°F r e q u ir e d ab o u t th r e e to f o u r h o u rs to r e a c h th e 11zone o f c r y s t a l l i z a t i o n 1*• I t to o k o n ly one hour f o r th e s te a k s i n th e -2 0 °F to r e a c h th e "zone o f c r y s t a l l i z a t i o n " o f meat* As a m a tte r o f i n t e r e s t , i t to o k a b o u t e le v e n h o u rs f o r th o s e s te a k s f r o z e n i n th e 0°F f r e e z e r t o come a t e q u ilib r iu m w ith th e te m p e ra tu re o f th e f r e e z e r . I t to o k o n ly seven h o u rs f o r th e te m p e ra tu re o f th e s te a k s f r o z e n in th e -20°F to come to e q u ilib r iu m w ith th e te m p e ra tu re o f th e f r e e z e r . I t was u s u a lly o b se rv e d t h a t t h e fo llo w in g m u sc le s: S p i n a l i s d o r s i , L ongissim us c o sta ru m and T ra p e z iu s d is c o lo r e d v e ry q u ic k ly d u rin g t h e f r e e z in g p r o c e s s , w hereas th e c o lo r o f th e L o n g issim u s d o r s i m u scle was v e ry slow t o show any d i s c o l o r a t i o n . The a u th o r b e l i e v e s t h a t p re h a n d lin g c o n d itio n s (su c h a s le n g th o f "bloom ing" p e r io d , -4 2 - o o -p (0 o 03 o 03 o O o O S3 C O EC rH •H -f-> tuj C •H N u 00 03 t-3 Q> ttf) *H 1*4 o 10 20 15 In d e x o f F a d in g -U n its from S tan ta n d ard a rd 7 . OR 4 .0 /8 .0 43- R a te o f F r e e z in g C u rv es o f S te a k s F ro z e n a t 0°F and -2 0 ° F F r e e z e r L egend: ----------- R a te o f F r e e z in g in -2 0 ° F F r e e z e r 40 ----- T e m p e ra tu re o f -2 0 ° F F r e e z e r R a te o f F r e e z in g i n 0°F F r e e z e r T e m p e ra tu re o f 0 °F F r e e z e r 0°F 20 Temperature 30 10 -10 -2 0 F ig u r e 1 3 . 12 Time In H ours -4 4 - 16 20 24 tim e i n t e r v a l b e f o r e th e p ackage i s p la c e d i n t o th e f r e e z e r , and th e r a t e o f f r e e z i n g ) h a s a marked e f f e c t on th e i n i t i a l d i s c o l o r a t i o n o f p rep ack ag ed f r o z e n m eats* The i n i t i a l c o lo r d e g r a d a tio n may be due to th e e f f e c t o f te m p e r a tu re on en zy m atic a c t i v i t y i n m eat. G o rtn e r (1949) h a s shown t h a t en z y m atic a c t i v i t y i s r e l a t e d to te m p e r a tu re . e n zy m atic a c t i v i t y i s slow ed down. W ith a f a l l i n te m p e r a tu re , F a i r l e y (1957) s t a t e d t h a t th e cy to ch ro m e- o x id a s e sy stem r e p r e s e n t s a b o u t 90% o f th e oxygen u p ta k e by th e t i s s u e . C jrto ch ro m e-o x id ase ta k e s up oxygen from m yoglobin w hich a c t s a s an oxygen r e s e r v o i r i n th e t i s s u e . In t h i s r e a c t i o n , oxygen may be p ic k e d up from m yoglobin by th e c y to c h ro m e -o x id a se system to c a r r y on th e r e s t o f th e m e ta b o lic f u n c t io n s o f m uscle m e tab o lism . The d i s c o l o r a t i o n o f t h e s te a k s k e p t i n t h e c o o le r i n an oxygen im perm eable wrap was b e lie v e d to be due to t h e enzymes i n th e m eat p ic k in g up th e r e s i d u a l oxygen i n th e package and re d u c in g oxym yoglobin to red u ced m yoglobin, w h ereas i n th o s e s te a k s t h a t w ere f r o z e n , th e en zy m atic a c t i v i t y was slow ed down due to th e f a l l i n tem ­ p e ra tu re . I f s te a k s a r e q u ic k f r o z e n a s was s u g g e ste d by J e n se n (1 9 4 9 ), th e en zy m atic a c t i v i t y i s slow ed down f a s t e r th a n th e oxygen u p ta k e by th e enzymes and oxym yoglobin i s n o t red u ced to m yoglobin. The im p o rta n t f a c t to be d e riv e d from th e s e s tu d ie s i n o r d e r to o b s e rv e w h at e f f e c t th e y have on i n i t i a l d i s c o l o r a t i o n o f p rep ack ag ed fro z e n m eat i s th e m anner i n w hich th e meat p ro d u c t i s h an d led b e fo re b e in g s e n t to t h e f r e e z e r and th e r a t e o f f r e e z in g o f th e p ro d u c t. These s tu d i e s p o in te d o u t th e n e c e s s i t y o f se n d in g m eat p r o d u c ts to th e f r e e z e r a s soon a s p o s s i b l e a f t e r i t i s p a ck a g ed , e s p e c i a l l y i n an oxygen im perm eable w rap. These s tu ­ d i e s a ls o p o i n t o u t th e n e c e s s i t y o f q u ic k f r e e z in g a t -20°F o r lo w er i n o r d e r to m a in ta in th e o r i g i n a l c o lo r o f oxym yoglobin. -4 5 - ®• E f f e c t o f R ep e a ted F re e z in g and Thawing on M yoglobin o f P rep ack ag ed F ro z e n M eat. A re v ie w o f th e l i t e r a t u r e r e v e a le d no in fo r m a tio n c o n c e rn in g th e e f f e c t o f r e p e a te d f r e e z i n g and th aw in g on th e p igm ent m yoglobin when packaged i n an oxygen im perm eable t r a n s p a r e n t p l a s t i c w rapper and aluminum f o i l . M angel (1951) fo u n d t h a t when sam ples w ere allow ed to thaw from one to f i v e tim e s t h e m ethem oglobin fo rm a tio n d id n o t in c r e a s e w ith r e p e a te d thaw ing* S a u r ie s thaw ed t h r e e and f o u r tim e s showed th e lo w e st p e r c e n t m etm yoglobin f o rm a tio n . She d id m en tio n t h a t a l l sam ples thaw ed more th a n once showed s u r f a c e d a r ­ k e n in g . B rooks (1929) r e p o r te d t h a t f r e e z i n g and thaw ing had no s i g n i f i c a n t e f f e c t on oxygen p e n e t r a t i o n , b u t d id a c c e l e r a t e m ethem oglobin fo rm a tio n i n th e r e g i o n o f oxygen p e n e t r a t i o n . R e s tilts o f t h i s s tu d y showed c o n s id e r a b le v a r i a t i o n i n th e p e r c e n t o f m etm yoglobin fo rm a tio n a s shown i n F ig u re 14. S te a k s a f t e r h av in g b een f r o z e n f o r tw e n ty - f o u r h o u rs e x h ib ite d a c o lo r c h a r a c t e r i s t i c o f oxymyoglo­ b i n , w ith a p e r c e n t m etm yoglobin fo rm a tio n o f 0 .3 6 and 2 .0 2 p e r c e n t metmy­ o g lo b in from s te a k s packaged i n Cry-O-Wrap and aluminum f o i l , r e s p e c t i v e l y . The p e r d e n t m etm yoglobin fo rm a tio n changed v e ry l i t t l e a f t e r th e s te a k s w ere f r o z e n f o r tw e n ty - fo u r h o u r s . A f te r th e f i r s t thaw ing c y c le , th o s e s te a k s p ackaged i n Cry-O-Wrap e x h ib ite d r e d and p u r p li s h b lo tc h e s c h a ra c ­ t e r i s t i c o f o x y - and re d u c e d m yoglobin. A f te r th e second thaw ing c y c le , t h e s te a k s packaged i n Cry-O-Wrap p l a s t i c b ag s showed much d i s c o l o r a t i o n . The s id e o f th e s te a k s n e x t t o th e n o n -fo ld s id e o f th e aluminum f o i l pack ag e showed a c o lo r much th e same a s t h a t e x h ib ite d by th o s e s te a k s packaged i n Cry-O-W rap. T h is seems to i n d i c a t e t h a t aluminum f o i l i s somewhat oxygen im p erm eab le. The s id e o f th e s te a k n e x t to t h e f o l d s id e o f th e package -4 6 - igure E ffect 140 of Repeated Freezing and Thawing on Metmyoglobin •rj r-f T-t Ch << O CO o Number r-t fa LO to CO -4 7 - CM ^ uxqoxEoERi^exi tu eo u e^ o of C ycles F o rm atio n o 00 CO rH O O oo iaO e x h i b i t e d a re d c o l o r c h a r a c t e r i s t i c o f oxyn$roglobin up to th e f o u r t h thaw ing and r e f r e e z i n g c y c l e , a f t e r w hich i t s t a r t e d to d i s c o l o r • F ig u re 14 shows an a l t e r n a t e in c x 'e ase and d e c r e a s e o f p e r c e n t m etm yoglobin fo rm a tio n w ith a l t e r n a t e th aw in g and f r e e z i n g c y c le s . Those s te a k s packaged i n aluminum f o i l showed a b o u t t h e same p e r c e n t m etm yoglobin fo rm a tio n a s th o s e s te a k s pack ag ed i n Cry-O-W rap, The s id e o f th e s te a k s packaged i n aluminum f o i l n e x t to t h e p ack ag e f o ld i n w hich th e r e was some a i r showed a p r o g r e s s iv e i n c r e a s e i n p e r c e n t m etm yoglobin f o rm a tio n . F ig u re 15 shows t h a t th o s e s te a k s packaged i n Cry-O-Wrap and th e s id e o f t h e s te a k s i n aluminum f o i l n o t n e x t to th e package f o ld d is c o lo r e d a t ab o u t t h e same r a t e , w h ereas th o s e s te a k s n e x t to f o ld s id e o f th e aluminum f o i l p ack ag e d id n o t d i s c o l o r u n t i l ab o u t th e f o u r t h thaw ing and r e f r e e z i n g cy cle* No a tte m p t was made to stu d y f u r t h e r th e r e l a t i o n s h i p o f enzy m atic a c t i v i t y a s r e l a t e d to thaw ing and r e f r e e z i n g o f meat* C, The E f f e c t o f L ig h t on C o lor D e g ra d a tio n o f P repackaged F ro zen Meat* Tn o r d e r to p r o p e r ly a n a ly z e th e r e s u l t s o f th e e f f e c t o f l i g h t on c o l o r d e g r a d a tio n o f p rep ack ag ed f r o z e n m eat, i t i s n e c e s s a ry to become a c q u a in te d w ith th e s u b je c t o f p h o to c h e m is try , Blum (1941) s t a t e d t h a t p h o to b io lo g ic a l p r o c e s s e s a r e e s s e n t i a l l y p h o to ch em ical p r o c e s s e s . P h o to ­ c h e m is try i s th e s tu d y o f ch em ical r e a c t i o n s produced d i r e c t l y o r i n d i r e c t l y by means o f r a d i a t io n * I t i s p o s s i b le to a c t i v a t e m o le c u le s w ith an e x t e r n a l s o u rc e o f e n e rg y , a s f o r exam ple, by in tr o d u c in g a beam o f l i g h t h av in g th e p r o p e r fre q u e n c y to be ab so rb e d and s u f f i c i e n t en erg y i n each p h o to n t o a f f e c t th e r e a c t i o n . A p h o to n o f r a d i a t i o n i s a u n i t o f r a d i a t i o n w hich p o s s e s s e s one quantum o f energy* w ith th e te rm p h o to n . F r e q u e n tly , th e te rm quantum i s used in te r c h a n g e a b ly In th e p rim a ry p h o to c h e m ic a l p r o c e s s each m o lecu le -4 8 - Effect 15# Freezing and Thawing On Metmyoglobin bO § CO c3 0 * 8 /0 * f -4 9 Number of C ycles O T-! O S^xup— 3uxpnj[ jo xopu j Figure of Repeated F o rm atio n o rH 00 O •oo S3 -H -H T3 01 ihd S g3 « HiB rH —D o Ch P. O M Ol rH O <1> to t 3 too o *H O CO Q 0*8/0*fr HO*2, pjrepire^s ra0J^ JO X 0 P U J -5 7 - \ TJ W U \ o Time QO*r4 Storage NM In Days S I—t CO 20. a H U) o Figure in UTqox^Oito^aH ^ u 9 0 J9 j -5 8 - A b s o r p tio n S p e c tr a For E x tr a c t s From F rozen S tea k s S to re d In D arkness And Under 56 F o o t-c a n d le s o f F lu o r e s c e n t Illu m in a tio n 14 <310 O O — 0 L egend: I n D a rk n e ss 1 Day o f S to r a g e • ----- 35 Days o f S to r a g e U nder 56 f t c L ig h t --------------- 1 Day o f S to r a g e 35 Days o f S to r a g e 520 F ig u r e 21 540 Uave L e n g th I n M illim ic r o n s -5 9 - 3# C o lo r D e g ra d a tio n o f P rep ack ag ed F ro z e n Meat Under th e Same L e v e l o f I ll u m i n a t i o n a t Two D i f f e r e n t T em p eratu res T h is s tu d y was co n d u cted to se e w hat e f f e c t 56 f o o t- c a n d le s o f illu m ­ i n a t i o n a t two d i f f e r e n t te m p e ra tu re s would have on d e g r a d a tio n o f c o lo r i n p re p a c k a g e d f r o z e n m e at. A t o t a l o f t h i r t y - s i x s te a k s were u sed i n t h i s s tu d y . d iv id e d i n t o f o u r g ro u p s o f n in e s te a k s e a c h . Group I . T hese w ere These gro u p s w ere a s f o llo w s : S to re d i n th e S h e re r s e l f - s e r v i c e c a s e i n d a rk n e s s . Group I I . in a tio n . S to re d i n th e s e l f - s e r v i c e c a s e u n d er 56 f o o t- c a n d le s o f illu m ­ I t was n e c e s s a ry to t u r n th e s e s te a k s o v e r each day a t a s p e c i f i c tim e i n o r d e r t h a t b o th s id e s o f th e s te a k r e c e iv e e q u a l ex p o su re to l i g h t . Group I I I . S to re d i n a 0°F f r e e z e r u n d e r 56 f o o t- c a n d le s o f i l l u m i n a ti o n . These s te a k s w ere t r e a t e d i n th e same manner a s th o s e i n Group I I . Group IV. T hese s te a k s were s to r e d i n a f r e e z e r i n d a rk n e ss a t 0 °F . S te a k s w ere removed a t v a r io u s i n t e r v a l s o f tim e , w ith th e l a s t s te a k b e in g removed a t th e end o f f i v e w eeks. S u rfa c e c o lo r m easurem ents and s p e c tro p h o to m e tr ic e s tim a tio n s o f m etm yoglobin fo rm a tio n were made i n th e same manner a s d e s c rib e d i n th e p r e lim in a r y s tu d y . F ig u r e s 2 2 , 23 and 24 show th e r e s u l t s o f th e e f f e c t o f th e same l e v e l o f i l l u m i n a t i o n a t two d i f f e r e n t te m p e ra tu re s on c o lo r d e g r a d a tio n o f p r e ­ packaged f r o z e n m eat. Im m ediate M unsell r e a d in g s a s shown i n F ig u re 22 show t h a t th o s e s te a k s s to r e d i n d a rk n e s s i n th e 0°F f r e e z e r d id n o t d i s ­ c o l o r to t h e same e x te n t a s th o s e s te a k s s to r e d i n th e s e l f - s e r v i c e c a s e u n d e r l i g h t and d a rk n e s s as w e ll a s th e s te a k s s to r e d i n th e f r e e z e r u n d e r lig h t. A f t e r a f o u r - h o u r “bloom" p e r io d , F ig u re 23 showed t h a t th o s e s te a k s s to r e d i n d a rk n e s s i n th e f r e e z e r , and s te a k s s to r e d u n d er l i g h t i n th e -6 0 - 'igure 22. D egradation of Prepackaged •H X3 o co CM 0 # 8 / 0 #k r-f oo c va *—I £ 0 * 1 iu o j c j - 61 CO •H U) O -P M to co o s^xun-Suxp-eji j o x o p u i In Days o Time of Frozen Steaks O Storage Color Stored In Darkness and Under I l l u m in a t i o n CO 03 -P M oo C/J £ 0 •H N O O o o u ts.0 0 txO 4-1 oo CtJ 0 ctS P-t 0 S -i 01 w o jj sjx u n f r e e z e r b r ig h te n e d a f t e r a f o u r h o u r •♦blooming p e r i o d ” . Those s te a k s s to r e d i n th e s e l f - s e r v i c e c a s e d id n o t b r ig h te n to any e x te n t a f t e r a f o u r h o u r '♦blooming p e r io d ” . F ig u re s 24 and 24a show th e e f f e c t o f th e same l e v e l o f i l l u m i n a t i o n a t two d i f f e r e n t te m p e ra tu re s on th e f o rm a tio n o f m etm yoglobin. S te a k s s to r e d i n d a rk n e s s i n th e f r e e z e r showed th e l e a s t in c r e a s e i n th e f o rm a tio n o f m etm yoglobin when b o th im m ediate and f o u r h o u r r e a d in g s w ere m ade, how ever, t h e r e was an i n c r e a s e o f m etm yoglobin from th o s e s te a k s a f t e r a f o u r h our ”bloom ing p e r i o d ” . S te a k s s to r e d u n d er l i g h t i n th e f r e e z e r showed l e s s m etm yoglobin f o rm a tio n th a n th o s e s te a k s s to r e d i n th e s e l f s e rv ic e case in d a rk n e ss. T here was r e l a t i v e l y l i t t l e change i n m etm yoglobin f o rm a tio n a s a r e s u l t o f th e ” bloom ing p e r io d ” . S te a k s s to r e d u n d e r l i g h t i n th e s e l f - s e r v i c e c a s e showed th e g r e a t e s t amount o f m etm yoglobin f o rm a tio n , how ever, when allo w ed to ”bloom” f o r f o u r h o u rs t h e r e was a d e c re a s e i n m etm yoglobin f o rm a tio n . I n g e n e r a l th e r e ­ s u l t s may be summ arized a s f o llo w s : 1. Meat s to r e d i n th e f r e e z e r i n d a rk n e ss showed th e l e a s t f o rm a tio n o f m etm yoglobin, b u t an in c r e a s e o f m etm yoglobin a f t e r th e f o u r h o u r "bloom ing p e r io d " . 2. Meat s to r e d u n d e r l i g h t i n th e f r e e z e r showed l e s s m etm yoglobin fo rm a tio n th a n s te a k s s to r e d i n d a rk n e ss i n th e s e l f - s e r v i c e c a s e . T here was no s i g n i f i c a n t change i n th e p e r c e n t m etm yoglobin a f t e r a f o u r h o u r "bloom ing p e r io d ” f o r th o s e s te a k s s to r e d i n th e f r e e z e r u n d e r l i g h t , b u t t h e r e was a d e c re a s e i n m etm yoglobin fo rm a tio n f o r th o s e s te a k s k e p t i n th e s e l f - s e r v i c e c a se i n th e d a r k . -6 3 - Hi Frozen O 'A o CO Storage Time Steaks Stored In Darkness and Under at Two D iffe re n t T e m p e ra tu re s. OM 'C j !• ~ - 64 - O uxqox^ojftiiieK ;u 0 o a3 c- 00 1 In Days o M Figure Prepackaged O 24. Metmyoglobin, F lu o resc en t I ll u m i n a t i o n ID CO CO o M Hi •rH •rH H I—1 bo M rH MW rH M M o O ■oH Q 00 O CO o o ■H • o o CO CO UTqox§Oi&x^8T^[ q u a o je j -6 4 a - 1-0 O 3* S te a k s s to r e d u n d er l i g h t i n th e s e l f - s e r v i c e c a s e showed th e g r e a t e s t fo rm a tio n o f m etm yoglobin, how ever, th e r e was a d e c r e a s e a f t e r a f o u r h our ^bloom ing p e r io d 1*, 4. C b io r D e g ra d a tio n o f P rep ack ag ed F ro z e n Meat S to re d Under V ario u s C o lo red F ilte rs R e s u l t s o f t h e two p re c e d in g s tu d i e s in d ic a te d t h a t l i g h t was d e tr im e n ta l to th e c o lo r o f p re p a ck a g ed f r o z e n m eat. T h e re fo re , i t was d e c id e d to f u r t h e r e x p l o i t th e a t t r i b u t e o f l i g h t w hich i s r e s p o n s ib le f o r t h i s d e g r a d a tio n o f c o lo r. I t h a s been shown by Kampschmidt (1955) and T a y lo r (1950) t h a t wave­ l e n g t h i s o n e o f th e m ost im p o rta n t f a c t o r s c a u s in g f a d in g o r d i s c o l o r a t i o n o f c o lo r e d m a t e r i a l s , such a s c o lo r e d t e x t i l e s and p ro c e s s e d m eats (su c h a s b o lo g n a , v e a l l o a f and b o ile d ham, e t c , ) . Kampschmidt (1955) r e p o r te d t h a t f o r c u re d m eats t h e r e a r e s p e c i f i c w a v e -le n g th s o f l i g h t w hich a r e ab so rb e d to a g r e a t e r e x te n t by cu re d m eats and b rin g ab o u t i t s d i s c o l o r a t i o n . He s t a t e d t h a t th e e f f e c t i v e s p e c tr a d i s t r i b u t i o n cu rv e i s h ig h e r i n th e r e g io n b etw een 400 mu and 550 mu th a n w a v e -le n g th s above 550 mu, W ith th e s e th o u g h ts i n m ind, a s tu d y was p lan n e d u s in g v a r io u s c o lo re d f i l t e r s w hich would allo w c e r t a i n w a v e -le n g th s o f l i g h t to p a s s th ro u g h them . more o r l e s s a p r e lim in a r y s tu d y . T h is f i r s t stu d y was No a tte m p t was made i n t h i s s tu d y to main­ t a i n t h e same l e v e l o f i l l u m i n a tio n on th e s t e a k s . E ig h t s te a k s packaged i n Cry-0-W rap w ere used i n t h i s s tu d y . was p la c e d u n d e r each o f t h e fo llo w in g l i g h t f i l t e r s : y e llo w , o ran g e and r e d . One sam ple p u r p le , b lu e , g re e n , One s te a k was h e ld i n d a rk n e ss and one s te a k s to r e d u n d e r S ta n d a rd Cool f l u o r e s c e n t l i g h t i n g . -6 5 - E x te r n a l illu m in a tio n o f 56 f o o t - c a n d le s was u se d w ith th e fo llo w in g l i g h t i n t e n s i t i e s f a l l i n g on th e s te a k a f t e r p a s s in g th ro u g h th e f i l t e r * These w ere a s f o llo w s : P u r p le . . • * * . 5 f o o tc a n d le s * • • • • • • • • • • * 2 f o o tc a n d le s • • • • * • • * . . * . . * * . 4 f o o tc a n d le s S lu e G reen Y ellow • • • • • • • • • * • • • • • • 4 4 O range • • • * * • • • « . • • • • • • f o o tc a n d le s 14 f o o tc a n d le s No f i l t e r ........................................................... 56 f o o tc a n d le s D ark n ess ...................* ......................... • • • 0 f o o tc a n d le s S to ra g e was f o r a p e r io d o f f i v e w eeks. S u rfa c e c o lo r m easurem ents w ere ta k e n a t v a r io u s i n t e r v a l s o f s to r a g e tim e by th e u se o f M u n sell s p in n in g d is k s * S p e c tro p h o to m e tric e s tim a tio n s o f m etm yoglobin fo rm a tio n w ere ta k e n b e f o r e and a f t e r sto ra g e # pH d e te r m in a tio n s were made* R e s u lts o f t h i s s tu d y seemed to show t h a t th e w a v e -le n g th s o f l i g h t betw een 560 mu and 630 mu (y e llo w and o ran g e p o r tio n o f th e spectrum ) a r e r e s p o n s i b le f o r th e d e g r a d a tio n o f th e c o lo r o f prep ack ag ed f r o z e n meat* T a b le V shows th e e f f e c t o f l i g h t t h a t h as p a s s e d th ro u g h v a r io u s c o lo re d f i l t e r s on th e fo rm a tio n o f m etm yoglobin. I t sh o u ld be n o te d t h a t th o s e s te a k s s to r e d u n d er th e o ran g e and y e llo w f i l t e r s showed t h e l a r g e s t i n c r e a s e i n m etm yoglobin f o rm a tio n , w hereas th o s e s te a k s s to r e d u n d e r th e g re e n and p u r p le f i l t e r showed th e l e a s t amount o f m etm yoglobin fo rm a tio n o f th o s e s te a k s s to r e d under v a r io u s f i l t e r s . 25 shows ib o u t th e same ty p e o f r e la tio n s h ip * s p e c t r a c u rv e s i n F ig u re 26 A re v ie w o f th e a b s o r p tio n shows t h a t th o s e s te a k s and u n d e r th e o ran g e and y e llo w f i l t e r F ig u re gave a sm a ll s to r e d u n d er nof i l t e r a b s o r p tio n peak i n th e a b s o r p tio n s p e c t r a c u rv e s a t a b o u t 505 mu w hich i s c h a r a c t e r i s t i c o f metmyo­ g lo b in * -6 6 - T able V C olor o f F i l t e r P e r c e n t M etm yoglobin P u r p le 38.49 B lu e 46.56 G reen 38 .0 4 Y ellow 53 .7 1 O range 60.26 Red 45 .5 9 Under l i g h t (no f i l t e r ) 59.40 Under no l i g h t 32.52 Under n o rm al e x t r a c t i o n p r o c e d u re s , a t h r e e mm s l i c e rem oves t h e m a jo r ity o f th e p ig m en t i n t h e s u p e r f i c i a l l a y e r . T h is d id n o t happen when s l i c e s w ere removed from th o s e s te a k s s to r e d u n d er th e o ran g e and y e llo w f i l t e r s . A f t e r t h e f i r s t t h r e e mm s l i c e was rem oved, i t was n o tic e d t h a t t h e r e w ere some b ro w n ish a r e a s u n d e rn e a th th e f i r s t s l i c e . S e v e ra l t h r e e mm s l i c e s w ere rem oved b e f o r e t h e r e w ere no more brow nish a r e a s . D epth o f d i s c o l o r a ­ t i o n was e s tim a te d to be a t a d e p th o f o n e - h a lf in c h . 5. C o lo r D e g ra d a tio n o f P rep ack ag ed F ro zen Meat S to re d Under V ario u s C olored F i l t e r s a t t h e Same L e v el o f I llu m in a tio n . A f t e r a n a ly z in g th e d a ta i n th e p re c e d in g s tu d y , i t was d e c id e d t o u s e th e g re e n , o ra n g e and re d l i g h t f i l t e r s i n t h i s s tu d y . R e s u lts o f th e p r e ­ v io u s stu d y showed no l a r g e d i f f e r e n c e s i n th e fo rm a tio n o f m etm yoglobin betw een th e p u r p l e , b lu e and g re e n f i l t e r s . -6 7 - no M 4-> rH CO O rH 0 *rHH fciO (x< § T3 rH PQ m & Q M 0 6 •H FH 0 tao kJ L t o -H 00 ctf -H 0 > H-» J* C/J 0 C/5 L O XS in CO M O c-f O O C*H CO Time In Days O CM 1—I *0 Storage t— 1 CD o UTqoxSojGu^eH luaouod - 77 - o Figure Metmyoglobin Under Stored In Darkness Illu m in a tio n and ro M t— i 3 CO and t h e p e r c e n t m etm yoglobin d ete rm in e d s p e c tr o p h o to m e tr ic a lly f o r d e t e r ­ m in a tio n o f s u r f a c e c o lo r o f f r e s h m eats* I n a t o t a l o f 114 sa m p le s, he fo u n d c o r r e l a t i o n c o e f f i c i e n t s betw een th e in d e x o f f a d in g and th e p e r c e n t m etm yoglobin ra n g in g from 0*830 to 0 .8 8 2 . He a ls o p o in te d o u t f a c t o r s r e ­ s p o n s ib le f o r p a r t o f th e u n c o r r e la te d v a r i a b i l i t y observed* C o r r e l a t io n c o e f f i c i e n t s were d eterm in e d to se e i f th e r e was any c o r r e ­ l a t i o n betw een in d e x o f fa d in g and p e r c e n t m etm yoglobin f o r d e te r m in a tio n o f s u r f a c e c o lo r o f f r o z e n meat* d a ta fro m 40 sam ples* F ig u re s 32 th ro u g h 35 p r e s e n t co m p a ra tiv e C o r r e la tio n c o e f f i c i e n t s betw een in d e x o f f a d in g and p e r c e n t m etm yoglobin were o b ta in e d by th e method o f S nedecor (1 9 4 6 ), and ra n g e d fro m 0 .7 7 ? to 0 .9 3 0 • These v a lu e s a g re e w e ll w ith th o s e o f B u tle r (1953) and i n d i c a t e t h a t w ith th e p e r io d o f in c r e a s in g fo rm a tio n of metmyog lo b i n , t h e r e i s a r e l a t i v e l y h ig h r e l a t i o n betw een in d e x o f f a d in g and p e r c e n t m etm yoglobin d e te rm in e d s p e c tr o p h o to m e tr ic a lly f o r p rep ack ag ed f r o z e n meat* -7 8 - i1igure Steaks 32. Stored In Darkness Between o 00 O - 79 - R eadings o 00 oCM JO xopui CM o ID ,o o 00 oCM O M etm yoglobin rH and Percent o of Fading Immediate CD Index Case. o C o rre la tio n In S e lf-S e rv ic e o 00 p Figure LO 33, Stored Between In Darkness C o rrelatio n Steaks Index of Fading In S e lf-S e rv ic e - Trial and Percent Case II o o CO o CM o J° xepuj - 80 o CT> CM o o CO IQ o M etm yoglobin CO o o to S-o Co lot Jo o- 00 o o r> co CVJ o o o L O M -H r Cl t: < uo O *r- o co pc o r < 11 o o 03 o LO o O O CO 3UTpBJ[ JO XOpiIJ - 82 - o tH O Figure 35, o C o rrelatio n -p Between Index CO and Percent O of Fading O CO 05 M etm yoglobin CD SUMMARY AND CONCLUSIONS 1# T e m p e ratu re v a r i a t i o n s i n a s e l f - s e r v i c e f r o z e n fo o d c a s e a f f e c t th e a p p e a ra n c e o f p rep ack ag ed f r o z e n meat packaged in tr a n s p a r e n t oxygen im perm eable w rapping m a t e r ia ls . 2. P re h a n d lin g c o n d itio n s and r a t e o f f r e e z in g a f f e c t i n i t i a l c o lo r d e g ra ­ d a t i o n o f p rep ack ag ed fro z e n m e a t. 3. R ep eated f r e e z i n g and thaw ing i n an oxygen im perm eable w rapper h as a marked e f f e c t on th e c o lo r o f prepackaged f ro z e n m e a t. W ith a l t e r n a t e f r e e z i n g and th aw in g c y c le s , th e r e was an in c r e a s e o r d e c re a s e o f m etm yoglobin f o rm a tio n . 4. D is p la y o f p rep ack ag ed f r o z e n meat u n d er in c a n d e s c e n t o r f lu o r e s c e n t l i g h t i n g c a u s e s d e g ra d a tio n o f c o lo r . T em perature o f d is p la y o f p re p ack ag ed f ro z e n m eat under f lu o r e s c e n t l i g h t i n g o f th e same l e v e l o f i l l u m i n a ti o n had an e f f e c t on c o lo r d e g r a d a tio n . Samples s to r e d u n d er f l u o r e s c e n t l i g h t i n g a t 0°F showed l e s s d i s c o l o r a t i o n and m etm yoglobin fo rm a tio n th a n sam ples s to r e d i n d a rk n e s s i n th e s e l f s e r v ic e c a s e in w hich th e r e was c o n s id e ra b le te m p e ra tu re f l u c t u a t i o n . 5. W a v e-le n g th s o f l i f h t betw een 560 mu and 630 mu (y ello w and o ra n g e p o r tio n o f th e spectrum ) seem to be r e s p o n s ib le f o r c o lo r d e g ra d a tio n o f p rep ack ag ed fro z e n m eat. 6. F ro ze n m eat s to r e d u n d er g re e n and re d f lu o r e s c e n t l i g h t i n g seem to g iv e b e t t e r c o lo r s t a b i l i t y o f prepackaged f r o z e n m eat, b u t g iv e s m eat an u n f a m ilia r ap p e aran ce when d is p la y e d u n d er such l i g h t i n g . -8 3 - 7, I t would a p p e a r t h a t th e y ello w p o r tio n (560 mu re g io n ) o f th e sp e c tru m e m itte d by w h ite f l u o r e s c e n t lamps commonly used f o r f r o z e n food d i s ­ p la y c a s e s and m a rk e ts i s r e s p o n s ib le f o r c o lo r d e g r a d a tio n o f p re p ac k ag ed f r o z e n m eat. 8. The f o rm a tio n o f m etm yoglobin i s th e p rim a ry cause o f d i s c o l o r a t i o n when p re p ac k ag e d f ro z e n m eat i n a tr a n s p a r e n t w rapper i s exposed to l i g h t . -8 4 - ■3 cj +■> 00 o• CM• 00© o o in o• + cj in O o. 6oh € O H -* -P o• o• in• o H r4 + + + 4* in« 4* I + +» O 4* 4* 4* 4 O in in O 0 CD 4 4* 4 O • O 0 O O O 0 0 CO CO 1 1 1 1 in• o* in• m• o0 CO H 4 CO T}4 CP o o• o• o• o• o• rH o CM c4 o o0 in0 1 1 4* CO WM 3 * •H {S Eh t 1 1 i I f 1 4* 4* rH CM I 4 1 o in0 O 4* 4 4 rH rH 4* 4 4* 4 4 4* 4* 4 4 1 1 1 1 rH 4* 4* 4* 4* 4* 4" I 4" 4* 4 1 4* 4 4* 4* 4 in0 o i I 1 1 CM rH 4* 4* 4 4- O 0 rH O O in © © O O 0 0 0 0 0 0 0 0 tH O CM CO in rH O rH + 4 4* 4* 4 i O 0 rH O o o o o o o o in0 in0 o0 o0 o0 o0 O0 O0 CO rH + O 4* 4> 4* 4* 4< 4* o O 0 in o in in0 O 0 O 0 CM CO "M4 rH tH 4' 4* 4 + O O © O O 0 0 0 0 0 0 0 0 0 0 0 0 00 C rH 00 CO HCD rH CO M4 CO rH CM rH 1 4* 4* 4 4* 1 1 1 1 4 4 1 tH 4* 4* 4* o0 CM0 O 0 O 0 O0 in0 O 0 O 0 O 0 CM0 CO0 CD CM rH o O CM CM CO rH H4 00 rH 0 4 O O O o0 o0 o o o in0 in 0 0 0 0 rH O H 4 rH 4* 1 1 i o in 0 0 0 0 O H4H4 in O O O O 0 0 0 0 0 0 00 00 CO rH rH "M4 CM CO rH rH rH 1 1 1 1 t 1 1 1 I 4* + 1 1 l O0 O0 in0 o0 o0 in0 in0 O0 o0 in0 o0 in0 O0 O0 o0 O# O0 in0 in in M4H4 rH o CM H 4 in 00 05 CM in 00 as CO rH rH 4* 4* 1 I 1 l 1 1 i I 1 1 1 4* 1 1 1 l in O0 O0 000 in0 CM0 o0 o0 000 o0 000 Oo m0 O0 in0 in0 O0 O0 0 4 o CM H 4 H4 CM rH CM rH rH rH in tH rH o CM o "M rH —1 CM T 1 4* 4 1 I 1 1 1 1 1 1 1 4 4* 4* 1 o0 © 0 in ■'sf I 4* rH CO 4-» (0 O 4* 4 o in0 in0 o0 o0 O 0 O 0 in0 O 0 o0 o CO H4 CM O o o © o 1 4 P 0 A 0 O +■» 4 O in a 0 0 05 in CO rH rH 0 O O 00 o CM o « • 0 • 0 tH CM CO CM CO 1 0 4* 4 1 4* 1 4 in0 in0 O 0 o0 in0 in O 0 # o CO in o CO CM rH rH O CM rH O 1 1 1 O O O 0 0 0 0 0 0 rH 00 CO rH rH CM CM rH 1 I 4 4* 4 4 0 in in• LO0 r4 CD 1 0 rH 00 O « « • • * CM CM CO CM CM + + O o O O in o O o o in in O O O CM 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 t — ■M4 rH i— 1 CM o rH CM rH rH rH ■ o M * 00 co CM rH CM 0 rH in o o o0 in0 O 0 o0 ina o0 o0 O O Q 0 in O 0 o0 ino CM0 OO0 O 0 0 0 0 CM CM tH rH o o CO CO CM H 4 rH in 00 H 4 O 0 in 4* i O 4* 4* 4 O 0 r4 4* 4* 4* 4' O • rH o• O • in• o• O o tH rl o o \— 1 4 4 O O + o0 o0 O • o0 O 0 in0 o0 O 0 in0 O 0 O 0 O o CM0 o o H4in CO CO CM t> a s o CO CM tH CO r4 00 rH rH CM CM 4" 4 4* 4 1 0 O • 4 O © 4* 4* in• o o in 4* 4- 4* m• O in 0 rH rH + PQ ■a ❖ a -8 5 - c y c le CO • r4 CO rl 4* + d efro st o0 in o• O second in CM o • 0 o o CM o r*I o 0 0 in in to S, © O CO in © © © O O in 00 O O in 0 0 0 0 0 • • o 0 0 0 0 0 0 0 0 OS CO CO CO CO in in ■M4 in in rH in a s CD LO CO CM rH rH rH 4 4 4* 4 * 4* 4* 4* 4* 4 4* 4* 4* 4 4 4* 4* 4* CM O O 0 due + ■M4 rH 4» O in tem perature o• LO ^ In crease * * • in• o• in o in + + 4* + in CM O A ppendix B* Time I n H ours 0 1 2 3 4 5 6 D e fro st 6 .5 7 8 9 10 11 12 13 14 15 16 17 18 *19 *20 21 22 23 24 «« - D ata C o lle c te d On T em perature V a r ia tio n I n S e lf - S e r v ic e Case __________When Loaded To C a p a c ity T em perature (°F) S teak No* s . 1 2 3 4 5 6 7 8 8 .5 8 .5 8 .5 9 .0 9 .0 9 .5 9 .5 + 14.0 + 11.0 - 2 .0 - 6 .0 - 7 .0 — 8 .0 - 9 .0 - 9 .0 - 8 .5 - 8 .0 - 8 .0 - 8 .5 - 9 .0 +10.0 - 5 .0 - 8 .0 - 8 .5 - 8 .5 - 8 .0 - 2 .5 3 .0 3 .0 3 .5 3 .5 3 .8 3 .8 + + + + + + + +11.0 +11.5 + 3 .0 0 .0 - 1 .5 - 2 .0 - 2 .0 - 3 .0 - 3 .0 - 3 .0 - 2 .8 - 3 .0 - 3 .5 +11.0 + 1 .5 - 1 .0 - 2 .0 - 2 .5 - 3 .0 2 .5 3 .0 5 .0 7 .0 8 .0 7 .0 8 .0 1 .5 - 1 .5 - 2 .0 - 2 .5 a 2 .5 - 3 .0 — 3 .0 + 20.0 +19.0 + 8 .0 + 4 .0 + 5 .5 + 5 .0 + 4 .0 + 4 .0 + 4 .0 + 3 .0 + 3 .5 + 2 .5 + 2 .0 +14.0 + 9 .0 + 3 .0 + 5 .0 + 7 .0 + 8 .0 - 1 .8 - 1 .0 0 .0 + 1 .0 0 .0 0 .0 0 .0 - 1 .0 - 1 .0 - 1 .5 - 1 .5 - 2 .0 2 .0 + 13.0 +15.0 - 1 .5 0 .0 - 1 .0 - 1 .0 + + + + + + + 8 .9 8 .9 8 .5 8 .0 8 .0 8 .0 7 .5 +13.0 +14.0 +25.0 + 17.0 + 18.0 + 16.5 +17.0 + 5 .0 + 7 .0 +17.0 + 9 .0 +10.0 + 7 .8 + 8 .0 + 12.0 +13.0 + 33,0 + 19.0 +22*0 + 17.5 +18.5 + 10.0 + 10.0 + 10.0 + 9 .5 + 9 .5 + 9 .0 + 9 .0 + 9 .0 + 9 .5 + 8 .5 + 9 .0 + 7 .0 + 8 .0 + 7 .0 + 6 .0 + 9 .0 + 8 .5 + 8 .0 + 7 .0 S to ra g e + 17.0 + 17.0 + 15.0 + 14.0 + 15.5 + 15.0 + 15.5 +15.0 +14.0 +13.0 + 13.5 + 11.0 +12.0 +12.0 +10.0 +13.0 +14.0 +13.0 +17.0 +37.0 + 17.0 +11.0 + 8 .0 + 6 .0 + 3 .0 + 7 .5 +9 .0 + 9 .5 + 7 .5 + 8 .0 + 4 .0 + 1 .5 +10.0 + 8 .0 + 2 .0 + 4 .0 + 3 .0 + 13.0 + 42.0 + 24.0 + 17.0 + 14.0 +13*0 +10.0 + 15.0 +15.0 +14.0 +10.0 +11.0 + 6 .0 + 7 .0 +15.0 +16.0 +16.5 + 5 .0 +11.0 + 18.0 10 Days 0 Time S te a k No. 1 2 3 4 5 6 7 8 H 9 .2 R 9 .9 R 9 .1 R 0.3YR 0.3VR 9 .8 R 9 .3 R 9 .3 R V C I % tmnb 4 .9 5 .0 5 .0 4 .6 4 .8 5 .1 4 .6 4 .5 5 .0 4 .8 4 .6 5 .1 4 .7 4 .1 5 .4 5 .8 1 4 .0 2 0 .8 2 0 .0 1 8 .9 1 7 .0 2 2 .8 1 6 .5 1 4 .7 0 .7 9 0 .7 9 0 .7 9 0 .7 9 0 .7 9 0 .7 9 0 .7 9 0 .7 9 H 0.2VR 1.7YR 0.2YR 9 . OR 9 .8 R 9.8R 3.1YR 3.7YR V C 3 .9 3 .9 4 .2 3 .9 4 .0 4 .3 4 .1 4 .9 5 .7 5 .0 5 .5 5 .9 6 .0 4 .6 3 .5 3 .0 I 1 4 .5 1 9 .0 1 5 .7 1 1 .7 1 2 .7 1 7 .0 2 2 .6 2 8 .4 $ mmb 8 .9 8 9 .6 8 6 .6 5 9 .8 3 9 .9 5 1 0 .1 0 3 5 .1 0 4 7 .8 0 ^ I n c r e a s e m te m p e r a tu r e due to seco n d d e f r o s t c y c l e . """"" H « Hue, V » V a lu e , C * Chroma, I = In d e x o f F a d in g , % MMb = F e r c e n t m e tm y o g lo b in . -8 6 - O o u < D0 acci 10.2 12.6 19.3 19.3 o « CM CM l l . l z CO in rH « rH 4 .0 tH CO CO CO . tH o. 00 in . tH CD • in CO . to CO . in 05 • LO o• o• H . H4 tH. o• o. o. 05 • CO M4 b 00 • o M4 ■M4 BCO inB P3 O • « tH o . o tH * tH tH H4 s IH . tH H4 H4 04 B oB B o. CM . CM OS a CM in 00. CO Data Collected On Prehandling 20.6 9 tfe HI t tn oi ^3 Sh O o CM in • 00 CM . OO oo• tH CO H H "M .4 CM CM 00 O . CM CO . ri4 CD • CD . CO tH . CO tH• <4* tH. PA • PA oo • tH CD CO rH O • CM CD CO . ■M 4 PA CO CD CM CO . CD • CM PA . tH* PA CH • CM tH rH♦ a 00 tH• . 'M4 CO . CO EC 00. CD tH tH. "M4 • CO . H4 00. CD tH tH t-. • CD . CM CM tH * 00 tH CD CD CO CM in . 'Cl4 CO co CO CO CD CO . B • CM P o• Si pA PA Pi CD CD+» U3 pH o • PC CM CM tH • CO CO • CM CD to tH• tH• "vf4 CO • M4 CO • M4 psj tH • CD « CO o P0 tH CO CM M4 • CO * CO • 00 tH si cn CO o CO • CM o ^J4 CO . oo S o tH tH CM « M4 00 CM • 3 X tH o tH o . O rH (0 S- PA to U 3 3 o x; si CM CO O - 87 • PA CD • CD to U 3 o Si • • oo CO CM CM CM CO CM H CM CD CO t> CO CM o CO CM CM CM CO CD CD 00 O CD • CO CO CO p • tH p • CM CO tH CO CO <0 & x O tH (0 $-1 3 o X! 00 • in to 3 o • • (0 U X) 3 o XJ tH CD * CM CD CO * M4 CD CD CO CO CO B 00 O B CO B CO 'O (1) > a Q ?» <9 £ S tH CO tH PQ • U si o o o o co II W •» ci e £ o 5h •rl x Xi o o tH n UQ C o g> -R o 0 3 tH +s-> c$ > 30 11 o 0 >■ eu •N ©a 3 PC X 3 1 Si X V* A ppendix D. _ Time In Hours D ata C o lle c te d On R ate o f F re e z in g In 0°F and -20°F F r e e z e r R a te o f F re e z in g i n -2 0 CF F r e e z e r T em perature o f S te a k s (°F ) T em perature o f F r e e z e r (°F) S te a k No. 1 S teak No. 2 0 i 2 3 4 5 6 7 24 -16°F -16°F -17°F -17°F -17 °F -18°F -18°F -17 °F -17°F +44 +29 +28 +22 - 5 .0 -1 3 .5 -1 5 .0 -1 7 .0 - 1 7 .0 +43 +30 +29 +22 - 5 .0 -1 3 .8 - 1 5 .0 -1 7 .0 - 1 7 .0 S teak No. Time o f M u n se ll R eading 0 1 2 3 4 5 6 7 24 Hour Hour Hour Hour Hour Hour Hour Hour Hour H S te ak No,► 1 I V C fo MMb H S te a k No. 2 V C I a in 00 • 05 tH • LO CO • CO © © tH CO tH © tH Tp © t- CM • rH CM tH • © Tp © © © • tH CM • © tH t• © • © O • Tp * t- C *•~ rH CM 05 • H4 00 • TP • a a a © B oo • o CM • CM CO • CM • tH CM in t- • CO tH O■ tH CM rH tH • CO • in• CO • • 00 tH CO CO O © • 05 C- • in LO • CO tH tP » tH • © a © • m © ©• © g © o • © tP © • © © © © • © tH © 05 • H4 © © O« © ©■ © • TP © 05 • © a © * t- o• TP • © ©• © a ©* o • 05 © rH • t- tH • tH CM tH C — © • • © H4 © ©• © ©• • Q • tH © © © • © ©• • tP © tH t- tP O• © © tP © • CO © • • • © H 4 a © • © © tH • tP ©• tP a ain ina a oa a ©B TaP a a a • • • • CO o o tH CO • CO pH CO • LO o • o O H CM o 05 C— • CO CO in LO • in o t- tH CO • o o• © • tH • in• TP CO 00 • tH tH ©• CO tH © © 05 © ©• © t-« O • © t• © © © C* © 05 © © © • © © ©• © tH • ©• © tH H4 • © • © ©• © H © o • tH tH © tH • H © • in ©# © CO • © tP Tp fc-• ©• CO tH • £3 B a a oa S • • • • • ©• • in H 03• CO • T j< tH Tp * 05 CD CO CO * O • tH a *8 tg •H G uo tH P t— I a atO> ^ •H O oXA N Q> p Pi o *H <0 X! TO u Q-i rf «H O a o U Pi p G o0 o C h § a> •rl PL, &-< CO pq • tH in CO • CO • CO • oo tH CO CO rH LO CM CO o tH o tH tH uo 05 eg O <0 I 05 & 'O TP tH © • O © o Tp © ©• © H CO M CM o CM • tP Pi * tP tH • tP 5 • © o• tH • © ©• tH © O• © • © ©• © tP • • © • C© o * © O• © Tp• © ©• ©• TP © ■M4 B ©a a a a • • • tP © 05 © 05 © © tH © © CD to eg u G •H CO >5 eg TO to eg o a> CO G O p CO tH I rH I H I § -9 3 - © I CO © I I * Index of Fading % MMb * Percent Metmyoglobin © P Hub Value Chroma •ao ii n ii BO > o 03 b- 03 IO g O CO o rH O • CM • rH 03 co CO CO • IO LO CO CO CO CO to CO rH PP H 03 • £§ & £ 00 in • o• O CM • CO • CM O 05 • • • CO t- O • CM • CO □H 00 • os b03 CM 'M4 0 a oa a a 0 CM 00 co 03 CO o CO • O « • • • o c— rH • CM * rH O • 05 b• IO LO b* LO • CD • o o O r t4 • O • CM rH rH LO 03 00 OO to • rH CM CM rH CM CM CM t• 00 rH 00 rH CO O IO CO b- CO to CO b- LO LO 00 • ■X4 ■M* CO 00 05 • 05 CO CO o •c^ 05 • rH CM * « CO • LO 00 LO rH 05 • LO 05 LO CM 00 rH CM • • • CO rH CO 00 • IO CO CO • 00 CO • CD CM • • CO 00 • LO LO LO • CM 00 • • rH 05 • LO O LO Xf g * CM CO 0) tu 03 n* CO • CO • LO • • • • • CO • CO • CO CO CO CO CM CO 0 0 a0J o0 s 03 rH 03 • O 03 rH CM rH • rH CO • • • • to ■M4 S co IO •M4 CM CO • CO cri CO in CO (0 CO rH IO O C- 05 • CO CM CO LO • O 00 CM • CO LO 03 05 • CO 05 • LO rH • to CO 03 s 00 in CM • CO 00 CM t> CM CO to b- 05 CM CM o CO ID 0 05 • rH CM CM 03 CM CO CO 00 CM r ji • CO tCM IO 00 • rH 03 CO • CO CO IO O CO • * O b- CD • • CO CM • rH CO PC • rH • 03 E3 o rH • IO • CO • LO M O LO IO • rH rH • CO CM LO CO rH LO • c— rl 05 os PH o CO rH T} H-> CO LO rH 6h o rH 03 o CD o b- CO • rH CM rH • 03 ■ brH o b- CM a oa a CO CD CM 00 • CO rH CM • O CM • b• CO CM U CO • rH rH • CO H CM rH ■ • • CM CO £g CM m 00 CO o O O LO LO • LO 00 00 ■M4 00 « 00 00 t• CM CO CO ■ CO LO ID CO • IO LO 05 03 CO • CM 00 rH CM CO CM CM CO o# CO a a IO 03 CO CO *2 S " Tf pH CD CD S CO O H-» § 6u0 W tbC £3 O *H s J3-d Cu cci -H o ccS o O to CtJ O £3 £3 £3 £3 •rl to XJ pq **• 5 >s Ctf X! to (0 £3 •H CO & >3 a •rl to I I s i s O U £3 to sI r H a ci XJ CO CO r HrH r H rHr H CM r rH H I a ^ ■M! OO C rH M 03 X3 CM o Pi •rl 03 x> •a 00 LO 03 CM O CM C M CM C I I s i s <0 (0 ttf 03 <3 O I i CO M CM I a Hue, V * Value, C = Chroma, I - Index of fading, % MMb = Percent metmyoglobin rH CM ti ffi co - 94 H © ^ W IO O O H © xf © © {*< r l r l • • • • rH r l C- t CM 0 r f CM CM CM a © Xl4 rl © • • t- © * © © CO CO CM CM 05 CO © • • • • B4 • ctj © O Q © • • © CM CM © * • • B CM © CO CM © © CO o • rl xf CM CO CO fc- © r l C - © CM • • CO CO a co CO x f Pi Pi © • Xf CO © rl • • xf xf LO • • 0 © 0 0 0 r H 0 © ©c HrH © s +* J2 HO CD TO x f © • • - • • • © © © © • • CO CO CO CM CO x f (h © • 00 O © © • © © O 00 O xj4 x f 00 5*4 'M4 CD Ce, o O • O u fcd © © C—© © CD • • • • • CD O CM CO CM fcrH rH Jk W Pi M • * CO O) r l 00 CD © 00 xf Xf CO LO O fr~ 00 00 © x f oo © 00 • a • • * CO x f CO CO CO CO • • © © CQ (0 CM CO t " t > CM O CM CM CM CM CM CM © • © x f fc"* CM CD c o Xf • • • • © O © Xt4X* © 05 © Xf © 1 CO O © © O C O C M C P C O rH C M • • © © rl © £ t - 00 H • © © B rH O q O W rl O O E-< r l 05 • Pi © • • © rH OO CM U • Xl4rH O 0 5 C © © © x j4 © • • • • • • • LO ^ t> T f LO OO 05 CM CM CO CM X*4 CO CO • * • CM © Appendix H. 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Si Si Si Si t/5 Ctj Q O r l© © X f © C D t> © *50 C? • rl •H (S3 CD CD U cd 0) > >> (» >3 w cti CD b ( J c f i f S - O 'd 'O ’O •a tj ts *d LO CM05 lp rHCOlOCOrlCMCMCO 5-1 ca >) CO (0 >1 05 {0 >s W cfl TO *o O CCS CCS ctj Ctj Cm T3 ra 'O * a © © CD © r l CO © © r l © - 95 - to to Ctj Ctj rO 'O © © © © of fading, % MMb * Percent metmyoglobin o o rH From Steaks Stored In Darkness and Under 56 Foot-candles Illum ination At Two D ifferent Tem peratures • CO 0 0 CO 00 CO O CM H N CO © e CO IO © © © © Value, C ■ Chroma, I ■ Index of F lu o re s c e n t o r H CM © © • • Ii > «* CD 5* W 1 ca g fc— O Tp CO CO CO CM tH • • • • • • • • CM CO CO CM CM CO LO tH tH 0 0 CO LO tH CO CD • • • • • • O • O 0 0 O tH tH LO CO LO O CM CM CD tH CO CO • • • • • • • * CM 0 0 tH CM LO LO CO O CM tH CM CM CM CM CM CO CD CM 0 5 tH LO Tp CO 00 • • • • • • • • tH CD CM 0 5 O rH LO CO tH tH CM tH CM CM CM CM CM t o O CO 0 5 TP tH • • • • * • • • t p Tp CO CO CM CM CO CM O 00 CM CO O CM 0 5 tH • • • • • « • • LO t P CO TP t P CO CM CM ec +» to w ft M sj £ s] •H to <3 0 ft! l-t 0 +-> <3 •r! o to 0 > pq 0 H. 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