Tenderness of Meat 11.
I.)ct.eririimatiori of Period of Aging Gradc A Heef Required to Produce a Tender Quick-Frozen I'roduct
I)ON.ALIJ K. THESSLEII AMJ W I L L I .T. ~ ~MURRAY,The Birdseye Laboralories, Cloucester, Mass.
T
HE quality of I d is deterriiiiitxl liotli iiy its teiidwrirss and flavor. Iiithis country all i ~ e isf ttwdered by holding at a temperature of 1 to :3' ('. Sor R jiwiod vtwying fran 2 days to x:vcral \ircks. This tciidi~ingeflect is brought about hy the action of eiiayrries mitainr.d in tlie tissues themselves and is coiniiionly h o w as aiit,oly I3eeE is geiierally coiisidcred to be US hetter flavor priur to tli enaynic actions of : iiir which produce t,be ttwirriiig. Severtheless, teiidernrw a qiiality so nnicli desired tint alriiost,all high-class meat is aged fur a t least i: week. I n a prcvions paper (i) the actioii of quick-frcesirrgand also that of subsequent storage at low tenrl~eraturcsin tendering meat have heir describrd. A considoratirw ( I f tliese results brought u p the qiiestirin of whether Cir riot it is pissiWe to age meat, to ij? quick-frown for a shortrr length of tirue, t,liiis
FlGunE
1.
ME:CA.kNICALLY
OPER.4TED
spectively, before being cut into steaks and treated as descrilred above in the case of tile KO. 1 aet of loins. At the end of storage for 1 month at - 18"C., all A steaks of each OS tlie sets were thawed, and their relative tenderness detmniued. Tlie B steaks of each set were allowed to remain in storage 3 moiitlrs, and the C steaks 6 months. In tlre previous paper ( 1 ) two novel instruments for determining the relistire tenderness of meat were described, arid the results obtained by tlxir use were cornpared. Since theii tlie results obtained with tliese instrunients have Been compared witli those ol>trtinrd 119tlie use of tlio one proposed by Warner ( 2 ) of tlie Tynited States Bureau of Aninial Indiistry. As a result of this rrork and a noinber of cooking tests on meat eritiriiiied by these iirstruments, it iias been eoricluded that more unifoxi resiilts can be ohtained with t.he penetronirt,er tliaii wit,h either of tlie other two instruments, and so this apparatus was employed in estimat,ing tlie relative tendernrs. Of tlie meat used in tliese experiments. I t is believed that the cause for the greater variation in single determinations olitained when either the cut,ting or perforating gage, or the dynaniometer instruments were used is that the prefienee of a greater or lesser proportion of cartilage arid connective tisme lias more effect OLI the reading of these instriiment.s which cut than it does 011the reading of the penet,roinetern.hich measures tlie depression iii the meat caused by a given force. Certaiii refinements in the technic eniployed in the use of both the perforating or cutting gage, aiid t,he penetrometer Iiave been introduced since the first paper ( I ) was submitted for puidicat,ion. The perforating gage has been mounted so t,liat it is noamechaiiically instead of hand operatrd (Figwe 1).
PER-
FOHITIXO G a o FOR ~ D TENUERYEYS OF MEAT
obtaining 1Jrtter flavored nieat arid yet a product a t ledst as tender as elrilled beef which tiad been aged longer. To prove this point, the experimental work deserilied helow was carried out. Twenty-one loins of freshly killed corn-fed steers were obtained and divided into seven sets of three each. The sets of loins were numbered from one to seven, and the three loins of each A, B, and C, respectively. Loins 1A, lB, and 1C were held 48 hours after slaughtering, then eight adjacent l'/,inch (2.9-em.) steaks were cut from the same section of each loin. The relative tenderness of tn.0 of the stealis from each of the three loins was determined immediately. The remaining six steaks cut from each of the three loins (1-4, 1B, and 1C) were individually wrapped in moisture-proof Cellophane and pacbged in cold waxed cartons. The packaged steaks were quick-frozen in a Birdseye multi&-plate froster and then stored at a temperature of - 18" to - 15" C. The sets of loins 2, 3, 4, 5, 6, and 7 were aged at 1a to 3' C. for 72, 96, 120, 144, 160, and 184 hours (after killing), re-
Inride dirneoiunn, 3 X 3 X I inch deep; maximum thickness 01 sumpie, inches: minimum thickness of sarnpie, 1 inch; diameter of holes, a/m inch.
The shallow cylindrical container forrrierly used as a container for the meat sample lias been replaced by a larger one having inside dimensions 3 X 3 X 1 incli (7.6 X 7.6 X 2.5 em.) (Figure 2), whicli is fitted witli a cover having eight 3/,incli holes through wliicli the penetration instrunient passes, thus making it posaible to perform eight, tests on a sample of meat of dimensions 3 X 3 X 1',lS inclies (7.6 X 7.6 X 2.9 em.). In testing tlie meat with the penetrometer, a TECHNIC. sample 3 X 3 X 1 ' j 8inches, free of fat and containing as little connective tissue and cartilage as possible, was cut. This sample w&s put iiito the nioiiel metal container and the cover placed in posit,ion. The container holding the sample was next placed in a press (Figure 3) and a pressure of 11.1 pounds per square incli (7.8 kg. per sq. an.) exerted thereoii; then the cover rvas Sastrired securely in place by means of
890
INDUSTRIAL
August, 1932
A 6 D
ENGINEERING CHEMISTRY
wing nuts and bolts on the sides. This was done to insure the sample's compactly filling the container. The portion of the sample protruding through the holes in the cover of the container x-as cut off with a razor so that the thickness of the sample was uniform throughout. The specially designed needle which has been described in the first paper ( I ) was forced into the meat through each of the holes in the cover with a 255-gram weight in the same manner as in the previous work. The average of the eight determinations, expressed in millimeters penetration, was considered an index of the tenderness of the meat.
RESULTSOF AGISG ASD STORAGE TESTS TESDERSESS OF STEAK PRIORTO FREEZISG.The indices of the relative tenderness of the steaks prior t,o freezing, obtained as indicated above, are given in Table I;. TABLEI. TENDERNESS O F SIRLOIN STEAKS S DAYS AT 1' TO 3' C.
A G E D FROM
891
These data indicate that there is a decrease in toughness of' sirloin steaks during aging throughout the duration of the aging test (8 days); this increase in tenderness is steady for the first 7 days and then becomes less pronounced. These results were checked by cooking tests. Organoleptic examination of the cooked samples indicated that the steaks aged 5 or 6 days were of better flavor than those aged longer periods.
EFFECTO F A G I S G , QUICK-FREEZING, AND STORISG The data comparing the relative tenderness of unfrozen steaks aged variois periods of time with that of the adjacent steaks which were similarly aged, then quick-frozen, stored at -18" C., thawed, and tested are presented in Tables I1 and 111. This work clearly indicates that the loins must be aged at CORIBIKED
2 TO
-ISDICES .~GING
S A M P L E PERIODLoin A Mm. Hours 1 48 13.8
2
72
12.7
3
96
13.9
4
120
14.0
5
144
16.7
6
168
18.2
7
192
19.3
OF TENDERNESS-4V. REMARKS Loin B Loin C of Set 31m. M m . illm. 11.1 12.5 1 2 . 4 Meat. not firm, hard to cut: fat very soft a n d jelly-like: meat tough and chewy 15.2 13.9 1 3 . 9 F a t firmer and whiter: meat still tough 12.9 15.9 14.2 Fat firmer: meat boned more easily owing t o firmness caused b y aging: moisture appearing on meat sign of tendering. tenderness of meat' fair, slightly chewy 14.9 17.5 1 5 . 4 Mean much more tender, slightly chewy in places; would be considered good 15.6 1 7 . 1 Steaks much more 19.0 moist a n d tender 18.0 19.4 1 8 . 5 Steaks very moist and very good a n d tender 18.3 18.8 1 8 . 8 Very tender
FIGURE 3.
hfEAT-SAMPLE PRESS
least 3 days a t 1O to 3" C. in order that the meat may be easily boned and cut into steaks. It is seen also that if sirloin steaks are quick-frozen after a short aging period, such as 3 to 5 days, the quick-freezing tenders the steak materially, but that after a longer aging period (e. g., 8 days) the tendering action of quick-freezing is less marked. Cooking tests both on fresh and quick-frozen sirloin steak indicate that this product is of
TABLE11. RELATIVE TENDERNESS OF GSFROZESSIRLOIN STEAKSAGED FROM 2 TO 8 DAYS,AND ADJACEXTSTEAKS C. SIMILARLY AGED AND THEXQUICK-FROZEN AND STORED 1 MONTHAT -18' S T E A K S OF LOINS .kGED, QUICK-FROZEN, A N D STORED .4T -18' c.
AGING SAMPLEPERIOD Penetration Hours M. m .. . .. . . 13.8 1 48 I
2
72
12.7
3
96
13.9
4
120
14.0
5 144 6 168 7 192 0 Examined while T.4BLE
STE.4KS OF
LOINS A G E D B E T NOTF R O Z E K ~ Remarks
Meat not firm, hard t o c u t : fat very soft and jellylike: meat tough a n d chewy F a t firmer a n d whiter: meat still tough
F a t firmer. meat boned more easily owing t o firmness c a d e d b y aging: moisture appearing on meat sign of tendering: tenderness of meat fair, slightly cheav Meat n k c h more tender: slightly chewy in places; would be considered good Steaks much more moist and tender Steaks very moist a n d very good and tender Very tender
16.7 18.2 19.3 fresh.
FOR 1 MOSTH Penetration Remarks Mm. .14.8 F a t slightly soft: meat moist mostly because of freezing' tough and chewy 15.8 F a t sbft and jelly-like in places: low penetration in places because of fat bruise throughout steaks; cookina tests indicate steaks fairlv tender: would be considered good: well flavored 17.1 F a t firm; meat moist (not excessively): steaks tender, JUICY, well flavored
18.9
Very tender, juicy, and well flavored
20.8 19.3 19.3
Very tender and juicy: flavor not so good as 3 a n d 4 Same as 5 Same as 5
111. RELATIVE TEXDERNESS OF
--
UNFROZEN SIRLOIN STEAKS AGED FROM 2 TO 8 DAYSLVD SIJiIILARLY A Q E D AND TIKEN QUICK-FROZEN AND STORED 3 MONTHSAT -18"
AGINQ SAMPLE PERIOD Penetration Hours Mm. 1 48 11.1
S T E A K S OF
LOINS A G E D
-
NOT FROZEN= Remarks
BC1'
Meat not firm, hard t o cut: fat very soft a n d jellylike: meat tough a n d chewy
ADJACENTSTEAKS
c.
STEAKS OF LOISS AGED, QUICK-FROZEN. A N D STOREDAT FOR 3 MOSTHS Remarks
Penetration Mm. 16.0
- 18O C.
2
72
15.2
F a t firmer a n d whiter; meat still tough
16.6
3
96
12.9
16.9
4
120
14.9
F a t firmer: meat boned more easily owing to firmness caused b y aging. moisture appearing on meat sign of tendering: tehderness of meat fair, slightly chewy Meat much more tender: slightly chewy in places; would be considered, good Steaks much more moist a n d tender Steaks very moist and very good a n d tender Very tender
F a t quite firm, jelly-like in only few places: storage caused setting of fat; fat and meat as a whole more firm a n d easier to cut t h a n when first packed; similar t o aged meat: cooking test, fair: may b e considered tender F a t and meat firm and cut easily: meat molst (not excessively) ' tender well flavored Steaks tender,'juicy. \;.ell flavored
17.6
Very tender, juicy, well flavored
18.5 18.4 19.4
Very tender: flavor not so good as 2, 3, a n d 4 Same as 5 Same as 5
5 144 6 168 7 192 Examined while
19.0 18.0 18.3 fresh.
892
I N D U S T R IA L A ND E N G I N E E R I NG C H E M I ST R Y
better flavor after aging for 4 to 5 days a t 1" to 3" C. than after longer aging a t this temperature. These tests also show that fresh and quick-frozen steaks aged for the same periods a t 1" to 3" C. are equally juicy.
COWLUSION
''
steaks aged days at to 30 and then packaged, quick-frozen, and stored at -I8" for a month Or longer when thawed, are as tender and of better flavor than
Vol. 24, No. 8
adjacent steaks aged 6 or 7 days a t 1" to 3" C. and then tested immediately without freezing. LITER.4TCRE
CITED
(1) Treader, D. K., Birdseye, C., and Murray, W. T., ISD. ENG. CHEM.,24, 242 (1932). (2) Warner, K. F., Proc. Am. Soc. A n i m a l Production, 1928, 114-16. RECEIVED April 11, 1932. Presented before the Divisions of Biological and of Agricultural and Food Chemistry at the 83rd Meeting of the American Chemical Society, New Orleans, La., March 28 to April I , 1932.
New Curve of Thermal Behavior of Gelatin &I. BRIEFERAND J. H. COHEN,The Atlantic Gelatin Company, Inc., Woburn, Mass. A new curve of the thermal behavior of gelatin 'RIGHT ( l c ) , followtheless significant in view of ing Arisz @),studied the discussion of Wright's inin solution is established showing the changes the effect of i n i t i a l teresting work. due to aging at different temperatures, the time The q u e s t i o n of v i s c o s i t y cooling temperatures of gelatin remaining constant. It is shown that at apsolutions and its r e l a t i o n to c h a n g e s of gelatin-water soluproximately 20" C. a solution of gelatin is in viscosity variation. I n this extions a n d g e l a t i n - i c e cream the most favorable condition to develop a structure periment with skim milk a temmixtures has occupied the attention of investigators over a perature range of 40" to 160" F. of m a x i m u m resistance to shearing stress. long period of time. Some of (4.4" to 71.1" C.) w a s u s e d . By means of curoes it is demonstrated that the more important references From these initial temperatures the structural changes as betrayed by jelly conthe gelatin solutions were slowly may be found in c e r t a i n absistency and viscosity measurements are similar cooled to 40" F. and the viscosistracts of l i t e r a t u r e (8). All ties determined a t 68" F. (20" f o r all types of gelatins irrespective of their of the published data are informative. Much of it, howC.). The rate of cooling, which previous history. T h i s thermal characteristic e v e r , is c l o u d e d b y extendwas different for each i n i t i a 1 m a y be considered a basic property of gelatin. ing t h e e x p e r i m e n t a l w o r k t e m p e r a t u r e , is not g i v e n . Gelatin incorporated in a n ice cream mixture beyond r e a s o n a b 1e temperaThe effect of the rate of cooling shows the same thermal behavior as pure gelatinture regions and by failure to for units of considerable volume observe t h e contributing water solutions. The maximum effect due to must be large, s i n c e u p o n it effects of s u b s t a n c e s mixed depends the average temperaaging is in the region of 20" C . f o r a n y approw i t h g e l a t i n , s u c h as milk ture to which the gelatin solupriate time period with a n y grade of gelatin, and cream. It will be unnecestion is subjected in the course irrespective of its origin or physical properties, sary to cite the m a n y o t h e r of the 24-hour aging p e r i o d . and in no case does it occur at a n y other temvariables which intrude upon inIncreasing the temperature from vestigators of this p r o b l e m . perature. 40" to 68" F. b e f o r e taking viscosity readings i n t r o d u c e s It is suggested that aging experiments be Mention should be made, however, of an excellent summary another variation. It will be conducted at 20" C . to insure comparable results given by Lucas ( I O ) . shown that reheating an aged in the hands of different inoestigators since in gelatin s o l u t i o n r e s t o r e s its P r i m a r i l y , the o b s e r v e d every case the m a x i m u m aging effect is obtained basic viscosity. effects due to aging a gelatin soat or near this temperature. l u t i o n a r e c h a n g e s of jelly Wright's c u r v e of i n i t i a l consistency and viscositv. The aging t e m p e r a t u r e shows a maximum in the region of 80" F. (26.7"C.) from which point authors ventured to find the specific relations that exist bethe curve is practically constant to 160" F. (71.1" (3.). I n tween viscosity, jelly consistency, time of aging, and temall probability the viscosities resulting from aging over this perature. The net results are expressed by a new curve of range of temperatures are affected both by the rate of cooling gelatin behavior which is designated as the characteristic and, a t the higher temperatures (100" to 160" F. or 37.8" to thermal curve of gelatin. The data are presented as a 71.1" C.), also by the growth or coagulation of the milk contribution t o the study of gelatin structure, thermal besolids. It will be shown that, when aging is restricted to havior, and thermal stability. In a previous communication ( 4 ) the authors have shown temperature effects only, the resultant viscosity curve takes a different form. I n Wright's experiments with ice cream that a t approximately 24" C. the viscosity of gelatin solutions mixtures the gelatin is added before pasteurizing and homog- increases with time of standing, if undisturbed. This enizing. Since hydrolysis of gelatin, owing to temperature observation is in agreement with the earlier work of Loeb and pressure, varies for different specimens, the results of (9). The authors, however, concluded that this viscosity such experiments may be open to question. Wright, how- increase was in reality incipient gelatin. I n view of the ever, anticipated in part the procedure followed in this study results obtained from the present experiments, it is apparent as being the more logical course to pursue. The studies of that this whole question of viscosity increase with time is Horrall (7) and of Anderson, Lyons, and Pierce ( I ) , while much more involved and that the forces operating in this not applying directly to the present investigation, are iiever- interesting phenomenon remain still undefined.
Mi
