Comparison of different peptidase substrates for evaluation of microbial quality of aerobically stored meats.

Different aminopeptidase and endopeptidase substrates were assessed for the detection of enzymatic activity of microorganisms collected from the surface of aerobically cold-stored pork and beef. The most sensitive substrates were fluorogenic Ala-7-amino-4-methylcoumarin (Ala-AMC) or Leu-AMC and colorogenic Ala-p-nitroanilide (Ala-pNA). Activity on natural oligopeptides, e.