THE 30,000‐DALTON COMPONENT OF TENDER BOVINE LONGISSIMUS MUSCLE

ABSTRACT Eight tender and eight tough bovine longissimus samples were selected on the basis of significant differences in sensory tenderness score, Warner‐Bratzler shear force value and myofibril fragmentation index. Longissimus samples were removed from carcasses at 1 day postmortem storage (2°C). These samples were subsequently analyzed for sarcomere length, sarcoplasmic and myofibrillar protein concentration, collagen concentration, pH values, fat and moisture content. SDS‐polyacrylamide gel electrophoresis was used to further characterize the KC1 soluble myofibrillar proteins. No significant differences between groups were found for sarcomere length and chemical properties. A major difference, however, was detected between tough and tender muscle with SDS‐polyacrylamide gels. That is, the 30,000‐dalton component was present in tender longissimus, but it was absent in tough longissimus muscle. These results show that (1) the 30,000‐dalton component is closely associated with tender steak and high myofibril fragmentation; (2) tenderness can be objectively detected early during postmortem aging; and (3) the presence, or absence, of the 30,000‐dalton component offers the potential, after further investigations, of being useful as an index of tender or tough longissimus muscle.