A HISTOLOGICAL EVALUATION OF CONNECTIVE TISSUE IN LONGISSIMUS DORSI MUSCLE OF RAW AND COOKED PORK

Abstract

SUMMARY Differences between animals were significant in the amount of stained reticular tissue but not in the amount of collagen and elastin in the longissimus dorsi muscle of pork. Differences between sides of animals were significant for all three connective tissue components. This is probably not of biological value. The amount of elastin in the longissimus dorsi muscle in pork was very small. Heat treatment was found to affect reticular and collagenous fibers. The greatest amount of stained reticular tissue was evident in the meat when heated to 66°C internal temperature. A decrease in the visible amount of reticular fibers was evident when the meat was heated to 85°C. Upon heating the meat to 66°C, the amount of stained collagenic fibers was markedly decreased. A slight reduction in amount occurred with continued heating. No significant difference in amount of elastic fibers due to heat was found. Sections of cooked samples taken from the longissimus dorsi muscle from the lightest and heaviest weight classes of hogs had significantly more stained reticular and collagenous connective tissue fibers than the intermediate weight classes. The trend was similar for sections from raw samples from the same animals. L.E.E.‐Kramer shear values for the two heavier (95 and 109 kg) animal weight classes were significantly greater than values for the two lighter (68 and 82 kg) weight groups. For all except the heaviest weight class of animals, shear values were significantly higher when the meat had been cooked to an internal temperature of 66°C, intermediate in value when the meat was heated to an internal temperature of 85°C and lowest in value when the internal temperature was 38°C. The 109‐kg weight group was least tender (highest in shear value) at the 85°C internal temperature.