EFFECT OF POSTMORTEM CHILL AND FROZEN STORAGE ON PROTEIN-DEGRADATION OF BROILER RABBIT MUSCLES - ANALYSIS BY SDS-GEL ELECTROPHORESIS

Biochemical variations in proteins of broiler rabbit muscles (Longissi mus dorsi =LD; Biceps femoris = BF) held at chill (2-degrees-4-degrees -C) and frozen temperature (-10-degrees to -12-degrees-C) were typed t hrough SDS-PAGE. Electrophoretic pattern of extracts from prerigor LD and BF muscles revealed intrinsic differences between white and red mu scles. The number of bands were more in LD muscle extract than in BF. Protein components of 54 000 daltons just above the actin and 44 000 j ust below the actin band observed in LD were lacking in BF. Initial 6 hr chilling showed more marked influence on the banding pattern of BF muscle than that of LD muscle. The number of bands were reduced to 12 as compared to 15 bands in preaged BF muscle, possibly due to formatio n of actomyosin complex due to rigor mortis. The increased number of b ands in 24 and 72 hr aged muscles indicated degradation of proteins by endogenous enzymes. Protein band corresponding to 36 000 daltons disa ppeared after 6 hr aging and was not visible after 24 and 72 hr aging in either muscle, whereas 40 000 daltons band specific in preaged LD m uscle also disappeared after 6 hr chilling postmortem. The marked chan ge observed in the electrophoretic pattern in 48 hr frozen stored musc le was the development of 26 000/27 000 daltons band in both muscles w hich might be related to postmortem tenderness parallel to well docume nted 30 000 daltons band in cold and frozen stored chicken and beef mu scles