- Beall A NEW LOOK A T BEEF CARCASS E V A L U A T I O N PROCEDURES QUAL I TY F A C T O R S

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1 118 A NEW LOOK A T BEEF CARCASS E V A L U A T I O N PROCEDURES QUAL I TY F A C T O R S H. B. C R A l O The tern, quality, a s it refers t o meat includes a nunber of a t t r i b u t e s which motivate the c o n s u e r t o s e l e c t c e r t a i n meat cuts f r o m t h e retail show case and r e j e c t others. When one considers quality, the two a t t r i b u t e s t h a t are immediately brought into focus are color and marbling and r i g h t l y s o since these two c h a r a c t e r i s t i c s can be rapidly appraised visually. Color of meat, while not known t o possess any i n t r i n s i c value as a p a r t of quality, nevertheless, does have psychological and commercial significance since "desirable" color is associated with freshness and wholeso2ipeness, as well as, animal age. Therefore, since color and marbling occupy such a prominent position, I would l i k e t o conf'ine my remarks t o these two factors, paying p a r t i c u l a r a t t e n t i o n t o t h i s thing we c a l l marbling. In w. e f f o r t t o familiarize myself with color eval-dation procedures p r e v i o ~ s l yreported a t t h i s conference, I revieired the proceedings with t h e following r e s u l t s : Brady (19491, Vilson (L951), Bray (1951), Brady (1952) and Hall (1954). A l l mention that the spectrophotometer occupied a r a t h e r prcminent position as a color measurement t o o l. Wilson (1951), Brady (1952), Hiner (1954) and B r a y (1951) reported that Munsell spinning d i s c s were also r a t h e r extensively used. In f a c t tkx? l a t t e r author indicated that as a result of a p o l l of 47 questionnaires sent t o various agencies, 20 of these were using I'4.meel.l spinning d i s c s f o r meat color measurement. However, of t h i s number, only seven were satisfied with the performance of t h i s device. I n addition t o the spectrophotometer and Mnsell. discs, the res u l t of the p o l l conducted by B m y (1951) indicated that the following devices were also used f o r color measurement: Color comparator Munsell Meat Scale and Color Paddles (I have never seen these and Hiner (1954) states that they could not be obtained f r o m t h e k n s e l l Color Company), Photoelectric c e l l IIunter Color and Color Difference b t e r Ostwald Color Chips Fat Discs - Beall Xodachrome pictures Container Corporation Color C h a r t s

2 119, The netliods of color evaluation outlined above are concerned w i t h the appraisal of meat surface color. If we are t o understand the mechanism of c a l o r change, which, i n t h e final analysis, is w h a t we muat do, then it is necessary t o g e t beyond t h e s u p e r f i c i a l and into the basic aspects cf meat pigment and f a c t o r s responsible f o r i t s change. Schweigert (1954) states that there is a relationship between the color of beef muscle and i t s myoglobin altlrough other f a c t o r s a l s o influence v i s u a l color of muscle. Some astects of pigment extraction and chemistry are a l s o given. Craig et al. (1959), Fleming e t al. (1960), Briskey e t al. (1960), Ginger et al. n954), Henry and B r a t z l e r (1960) and other mrkers have evaluated muscle color by means of i t s woglobin content. The work of t h e former authors indicated t h a t there was reasonably good agreement between Munsell Color notations converted from Hunter Color and Color difference meter rearlings and n2yog.lobj.n concentration. I A t North Carolina S t a t e College we have i n i t i a t e d a study i n which we w i l l attempt t o explore t h e physiological and chemical aspects of meat color by determining the relationship between muscle ph, myoglobin, hem- globin, blood oxygen content and muscle t i s s u e p a r t i a l pressure of oxygen in beef s t e e r s on two exercise l e v e l s and two d i f f e r e n t rations. This i s an attempt t o g e t beyond the s u p e r f i c i a l. I n preparing t h i s paper f o r presectation, I thought it might be of i n t e r e s t t o p o l l some of our Colleagues i n an e f f o r t t o ascertain the type of research current?y being conducked i n the area, of beef m s c l e color. Out of 32 requests, I received 10 replies. O f t h i s nmber f o u r indicated they were working on some aspect of color and a f i f t h was i n i t i a t i n g work i n t h i s area. Vissouri listed several methods that they had used f o r color evaluation among which was a subjective panel. I might add that we a t North Carolina S t a t e a l s o use t h i s method. Oklahoma reported on the use of 8 Photovolt Reflectance Meter t o obtain h n s e l l Color notations. Their data indicated t h a t steaks from the Longissimus d o r s i muscle become darker red with advancing animal age and tend t o be l i g h t e r, b r i g h t e r red after aging 14 days. O f t h e Three Color Components, W s e l l value notation seemed most influenced by color differences since this p a r t of the notation decreased with advancing animal age and increased with increased meat aging time. The value dimension of Munsell Color, as you know, refers t o the whiteness o r grayness of a color and v a r i e s from 10 (white) t o 0 (black). - Arkansas also reported on the use of a 2hotoreflecteLnce Meter t o evaluate color. Likewise, t h e i r data were converted t o Nunsell Color notations. Two experiments were conducted. In t h e first, t h e e f f e c t of limited and full feeding with and without stress (with e l e c t r i c hotshot) on t h e color of t h e Longissimus, d o r s i Psoas major and Quadriceps femoris was evaluated. Stress s i g n i f i c a n t l y a l t e r e d color a s evidenced by Yunsell value change i n a l l three muscles in t h e r a w s t a t e and of t h e Fsoas major when cooked. As with the Oklahoma work, h n s e l l value was most influenced by color differences. In another study, WseU color notations were obtained on cooked and uncooked steaks and correlated with t h e following panel scores: aroma, flavor, texture, tenderness and juiciness. There was no appreciable relationship between color and any of these t a s t e panel 6 COF5S

3 120. The Michlgnn workers have long been interested i n meat color and a report from them indicated a study on purified beef myoglobin. Some yrel i m i W ~work there indicated the existence of a t least two, and perhaps several, d i s t i n c t myoglobin species i n beef muscle. Various chmmtographic columns were used i n t h e preparation of electrophoretically homogenous myoglobin and i n the separation of the electrophoretically d i s t i n c t myoglobin species. Analysis of iron content, absorption spectra and oxidation rates indicated only s l i g h t differences between the purified myoglobins. Another recent study a t Michigan involved the e f f e c t s of certain ions and l i g h t of various wavelengths on the color change i n frozen mlyoglobin extracts. Color was measured by means of -sell spinning discs. By way of summary remarks, l e t me make the obvious observation t h a t there are many methods f o r color evaluation. Some are suitable f o r c e r t a i n research undertakings while others are not. The nature of the probl e m d i c t a t e s t o some degree the method t o use. I have often wondered as did Wilson (1951) why we have not arrived a t a basic understandable standard method of color measurement o r appraisal t o use i n routine carcass evaluation work. Certain information on color is often d i f f i c u l t to i n t e r pret unless one is a color expert; and as a result, considerable research data i n t h i s area are a l l but meaningless. Now we come t o the second quality a t t r i b u t e that of Marbling. Generally, I w i l l confine my remarks t o a study we have made a t North Caml i n a State College. Let me add, a t the outset, that most of t h i s infonnat i o n has been submitted t o the Journal of Animal Science f o r official. publ i c a t i o n under t h e t i t l e, "Nature and Variability of Marbling Deposits i n Longissimus brsi m s c l e of Beef Carcasses"; and any reference t o t h i s work should c i t e this publication... I For several years a t North Carolina, we have used an objective nethod of measuring marbling developed by Rluxner and Fleming (1959). Thier method has been used on a large number of c a t t l e carcasses. It is desifped to measure the area of f a t deposits in the bnglsaimus d o r s i muscle in square millimeters. Application of t h i s method t o marbling evaluation to determine t h e effects of various breeding 8nd n u t r i t i o n experiments failed t o produce consistent r e s u l t s. The s.t;udy reported here was undertaken t o determine whether t h i s result wa8 due to variations of marbling content within the rib eye muscle o r due t o animal variation within treatments. Marbling was measured on the cut surface of the r i b eye muscle of 40 anim~sa t three locations a n t e r i o r t o the 13th r i b and posterior and a n t e r i o r to t h e 12th rib. In bne case, a five-fold variation i n the amount of marbling was noted and two-fold variations w e r e quite common. The average marbling area ( i n square mu.) for the 40 c a t t l e was 30 percent greater i n the surface cut posterior t o t h e 12th rib as compared t o that a n t e r i o r t o the 1 2 t h rib. These observations stimulated additional studies on locatioaal variation i n marbling of the Longissimus d o r s i muscle. This muscle waa remved fmmthe 9th, l o t h and l l t h r i b section of the right aide of 22 c a t t l e fed i n drylot o r pasture and ranging i n grade fr0m l o w standard t o low p r i m, The muscle sections were frozen, sawed i n t o 1/4-inch sections and subsequently scored t o the nearest 1/3 USDA marbling grade by three individuals.

4 121, In order to nore c l e a r l y i l l u s t r a t e dii'ferences i n t h e degree of marbling within each r i b section, t h e s l i c e s considered t o have the most, l e a s t, f i n e s t and coarsest marbling were determined. Ether e x t r a c t s were then made on each of these f o u r s l i c e s. Values were expressed on a f r e s h and dry weight basis; but since s t a t i s t i c a l differences were e s s e n t i a l l y i d e n t i c a l f o r f r e s h and dry weights, only the f r e s h weight values were used. Correlat i o n c o e f f i c i e n t s were determined on each of the f o u r s l i c e s with t h e i r corresponding ether e x t r a c t values. Standard deviations were a l s o calculated. Slide 1 indicates t h e range i n rnafbling grades over the 3-5S-inch muscle s e c m d the grade placed on the r i b eye m s c l e a t the 12th r i b. IvWBLING VARIATION C a t t l e No. w e Marbling Grade 485 s1 + t o sm 482 Sm 460 O to Me S1 + t o Mt - - Marbling Grade a t 12gh r i b s1 O sm O Sm O Cattle No. 485 doesn't show sufi'icient marbliug variation t o be graded out of t h e good gmde; however, No. 460 varies from low good t o low choice d i s regarding conformation. NG. 482 v a r i e s f r o m about average good t o w e l l i n t o t h e choice grafie and all i n the same animal. Coware t h e grades placed on t h e muscle a t t h e 1 2 t h r i b. It was noted that more v a r i a t i o n occurred i n the higher grading animals. Slide 2 shows the 1 4 s l i c e s obtained f r o m t h e m s c l e of C a t t l e No. rpqcl Notice, addition t o the quantity variation, the v a r i a t i o n i n the degree of coarseness. Observe t i e recurring p a t t e r n i n f a t d i s t r i b u t i o n, that is, several consecutive s l i c e s have coarse marbling fol?-owed by several that have f i n e marbliw. It w&8 noted t h a t the r i b eye muscle section immediately dorsal t o the r i b bone exhibited coarse marbling; whereas, f i n e marbling was observed i n between t h e r i b s. obviously, t h i s serves t o point out t h e f a l l a c y of s t a t i n g t h a t one animal is more f i n e l y marbled than ano t h e r when both conditions can be seen i n a single muscle dependent, in l a r g e measure, on the location of the cut surface Slices 3, 6, 7 and 9 indicate the f i n e s t, coarsest, most and least amount of marbling, respectively. Note that s l i c e s 7 and 9 are only 1 / 2 inch apart but e x h i b i t rather l a r g e differences i n marbling content. Ether e x t r a c t values were not determined on these s l i c e s, b u t values obtained from 1 9 other animals indicated t h a t t h e most chemical f a t was found i n the most and coarse categories, Less chemical f a t was found in the l e a s t - f i n e categories. In 60 percent of the cases, t h e s l i c e indicated by the grader t o have the coarsest marbling a160 had the most marbling. Correlations between the marbling score^) and e t h e r e x t r a c t values f o r least, f i n e, coame and most, respectively w e r e as follows: 0.92, 0.92, 0.91 and Standard deviations ranged from t o marbling scores. Ether e x t r a c t values varied from 4.96 percent t o 8.90 percent i n one animal.

5 122. Thus, variation seems t o be the rule; and methods f o r evaluation of differences i n marbling content by ether extract o r other means and t h e relat i o n of these to treatment e f f e c t s ar;d eating quality are not of great value. Since such great variation exists, it appears that we do need t o reevaluate our methods. It seems that i n older t o approach any degree of accuracy i n determining e t h e r extract, one shou3d use a rather large sample preferably the muscle section located from midpoint between two r i b s t o midpoint between t h e adjacent gair. Since considerable marbling variation was noted within each muscle, we attempted a further study of t h i s aspect, Twelve steaks cut one o r two inches i n thickness were removed f r o m the l o i n s of several carcasses. To determine whether o r not there was a definite pattern by which i n t m s c u l a r f a t was delpsited, a l l v i s i b l e marbling deposits on the t w o exposed surfaces of each steak were carefully dissected free of surrounding m a c l e tiss.ie. The method of procedure ma,y be mre readily discerned by observing Slide 3. Notice the extreme ramification and interconnection of the subsurface mrb l i n g branches. Slide 4 shows another view of the intense branching noted i n t h e Longissimus d o r s i muscle of the same animal. This dissection procedure indicated a large trunk-like portion of f a t t o be present i n a p p o x i mately each linear inch of t h e r i b eye nazscle. It may thus be discerned as t o w-hy there is a variation i n coarseness and amount of marbling depending upon the point a t which the m s c l e is cut. A cut through t h e large branches would r e s u l t i n exposure of a large marbling deposit which would not have been observed a t a l l had the muscle been cuf only a f e w millimeters t o the l e f t o r ri&t c 1 Slide 5 shows the r e s u l t of completely dissecting a large marbling._ deposit from i t s position i n a r i b eye steak. The characteristic marbling pattern seems t o consist of tree-like branches seemingly having t h e i r origin from f a t l o c i located adjacent t o the rib. The relationship of marbling deposits t o the blood vascular system was demonstrated by injecting a solution of India ink i n t o the i n t e r c o s t a l branches of the dorsal a o r t a i n the 6th, 7th m d 8th r i b section of a wholesale r i b cut. Sn Slide 6 a portion of the vascular system w i t h h the muscle and the f a t may be observed. The darker, upper portion of the slide i s muscle; the l i g h t e r, lower portion shone-the-masbling deposits. In Slide 7 the extreme right hand portion I l l u s t r a t e s a small blood vessel e x p m i n a marblix depoeit approximately 3 mm. i n diameter. Upon tracing t h e vascular system, it was found that the main t m k s of these m r bling deposits appeared t o be located close t o or within a heavy network of vessels. The fact that some variation i n marbling d i s t r i b u t i o n occurs has Many of been mentioned from t i m e t o time i n various research undertaklnga you have, no doubt, observed t h i s condition. I hope that t h i s discussion has sewed t o make us all more aware of t h e problems we face when we set out t o evaluate the marbling i n beef c a t t l e carcasses, Any objective method of marbling measurement must consider the inherent variation that e x i s t s i n a given r i b eye muscle,

6 123. Blumer, T.??, and H. E;, Fleming A method f o r t h e q u a n t i t a t i v e e s t i mation of maybling i n t h e beef r i b eye muscle. 5. Animal S c i. i a : Brady, D. E. research Some observations on chemical methods used i n meat Froc. Second Annual Rec. Meat C o d. 2: Brady, D. E Physical research methods. Meat Conf'. 5: , Proc. F i f t h Annual Rec. Bray, R. W Physical and h i s t o l o g i c a l phases of meat research. Fourth Annual Rec. Meat Conf. 4: Proc. Briskey, E. J., W. G. Hoekstm, R. TJ. Bray and R, H, Grumer A comparisou 02 c e r t a i n physical and chemical c h a r a c t e r i s t i c s of e i g h t pork muscles. J * Animal Sci. 19: Craig, E. B., T. I?. Slumer and E. R, Barrick Effect of s e v e r a l conbina?ions of g r a s s and g r a i n i n t h e r a t i o n of beef s t e e r s on t h e c o l o r characterlstics of l e a n and f a t. J. Animal Sci. 18: Fleming, H. P., T. N. Blumer a d I?. B. Craig Quantitative e s t i mations of myoglobin and hemoglobin i n beef muscle e x t r a c t s. J. Animal S c i 1 9 : Ginger, I. D., G. D, Wilson and B. S. Schweigert Biochemistry of myoglobin. Quantitative determination i n beef and pork muscle. J. Agr. and Food Chem. 2: Hall, J. L The spectrophotometer Tor meat color research. Seventh Annual Rec. Meat Conf. 7: Proc. Henry, W, E. and L. J. Bratzler Ef'fect of mineral supplementation on pork muscle color as measured by s2ectmphotometry and d i s c colorimetry. J. Animal Sci. 19: , Hiner, R. L Yiunsell d i s c s and c o l o r paddles as methods of measuring color i n?eats. Proc. Seventh Annual Rec. Meat Conf. 7: Schweigert, B. S Quantitative chemical measurement 02 myoglobin. Proc. Seventh Annual Rec. Meat Conf. 7: Wilson, G Physical, chemical and organoleptic methods of pork carcass evaluation with s p e c i a l reference t o firmness and color. Pmc. Fourth Anneal k c. Meat C o d. 4:

7 124. 1,115. COLE: That WES a very i n t e r e s t i n g paper by the North Carolina workers and f'urther coraplicates our work. Apparently we've s t i l l got a l o t of chores t o do i n evaluating beef carcasses. In 1953, as we stated, we I?ad measurements ado_nted by t h i s Conference, and M r. O r t s is now going t o talk t o us about carcass measurements.