Effects of freezing on the proteolysis of beef during storage at 4 degrees C.

The effects of freezing on the proteolysis of beef during storage at 4 degrees C after being thawed was investigated. A sarcoplasmic 32-kDa protein in frozen as well as unfrozen beef decreased rapidly during storage at 4 degrees C, and a more than 100-kDa protein appeared in both beef samples. And the increment of peptides in the frozen beef during the storage at 4 degrees C was larger than that in the unfrozen beef, suggesting that the proteolysis was faster during the storage of the former than the latter. However, its increment in the frozen beef for 10 weeks during the storage at 4 degrees C became smaller than that of the one frozen for less than 5 weeks. To discover an indicator for evaluation of the conditioning of frozen and unfrozen beef, peptides produced during the storage of beef at 4 degrees C were surveyed. A peptide, APPPPAEVPEVHEEV, was detected and seemed to be available as an indicator in the conditioning of beef.