EFFECT OF DRY-CURING PROCESS PARAMETERS ON PORK MUSCLE CATHEPSIN-B, CATHEPSIN-H AND CATHEPSIN-L ACTIVITY

The effect of chemical agents (salt, nitrate, ascorbic acid and glucose), and process parameters (water activity, pH and temperature) on porcine muscle cathepsins B, H and L was studied. Salt strongly inhibited cathepsin H activity. Only 40-50% of the original activity was recovered in the presence of 4-5% salt, typical of dry-cured meat products, while cathepsins B and L were less affected, recovering around 65-75% of their original activity. Ascorbic acid (above 1 g/L) strongly inhibited cathepsin H whereas glucose (up to 2 g/L) activated (around 30%) cathepsin B. Nitrate did not affect cathepsin activity. A decrease in water activity affected cathepsin B and H activity and cathepsin H activity was almost negligible below pH 5.5, which is usual in dry-cured sausage processes. All three enzymes were very active in the temperature range, 20-30-degrees-C, typical of dry-curing processes. A study in vitro, representing three stages of the dry-curing process of hams, revealed that cathepsins B and L might play an important role throughout the complete process whereas cathepsin H only participated in the middle and at the end of the dry-curing.