CHARACTERISTICS OF YOUTHFUL BEEF CARCASSES IN RELATION TO WEIGHT, AGE AND SEX: III. MEAT QUALITY ATTRIBUTES

Abstract

A total of 574 youthful beef carcasses from three sources comprising 168 steers, 147 heifers and 259 bulls were processed to study the influence of carcass weight, age and sex on beef quality. Source differences in pre-slaughter treatment were associated with differences in ultimate pH and in color of the longissimus dorsi muscle. Dark color and high pH values (pH > 6.0) were characteristic of the 1. dorsi muscle from bulls subjected to the greatest pre-slaughter stress. Stress effects markedly influenced palatability factors, with dark-colored bull beef from this one source scoring significantly higher for tenderness, juiciness and flavor than beef from steers subjected to the same pre-slaughter treatment. For these bulls the correlation between tenderness and meat color score was −0.50. Comparisons within source groups indicated that in meat color and shear values at 72 hr post mortem, heifers were superior to bulls and inferior to steers. After excluding the stressed (high ultimate pH) bulls from one source there were no significant sex-source differences in shear value at 13 days. However, taste panel evaluations indicated unstressed bull beef to be less tender than beef from heifers. Heifers had significantly more marbling than comparable bulls or steers, but differences in percent ether extract were significant only for the heifer-bull comparison. Correlations between live-weight and the various quality measurements were generally insignificant. A negative relationship was indicated between tenderness and age for bull carcasses (correlations about −0.3 in terms of merit) and the amount of chemically determined intramuscular fat of bulls was positively correlated (0.3 to 0.4) with age.