Effect of curing salt and phosphate on the activity of porcine muscle proteases.

The effect of curing salt on the activity of porcine muscle proteases was evaluated, within the salt concentration range found in the manufacturing process of Spanish cured ham. Salt (NaCl) acts as a strong inhibitor of proteolytic activity; sodium nitrate and potassium nitrate do not affect cathepsin D activity; cathepsin L is inhibited at levels of the salts not found in cured ham, and Ca-dependent proteolytic activity is enhanced by nitrate concentrations below 800 ppm. The appearance of phosphate precipitates in several areas of ham has led to the study of phosphate effect on enzymatic activity. Results show that phosphate is an inhibitor of proteolytic activity.