Examination of cathepsins B, D, H and L activities in dry-cured hams

Cathepsins B, D, H and L as well as the glycosidases β-glucuronidase and N-acetyl-β-glucosaminidase were assayed for activity in fresh pork muscles stored for up to 20 days at 4°C and in 3- and 8-month dry-cured hams. Cathepsin B, H and L activities fell by 40-79% after 20 days while cathepsin D activity remained unchanged. All the enzymes were still active after 8 months of dry curing; with the recoveries found to be in the range 14-73%. Contaminant microorganisms did not appear to contribute to the observed proteinase activities. Cathepsins B, H and L activities from the 8-month ham have been confirmed as cysteine proteinases by the use of specific inhibitors. It was further confirmed that the cathepsin B and L activities in fresh pork and dry-cured ham were similar by isoelectrofocusing. We suggest that the presence of the curing salts may be important in stabilising the muscle enzymes during the curing process.