Curing agents affect aminopeptidase activity from porcine skeletal muscle

The effect of curing agents (salt, nitrite, nitrate, ascorbic acid, glucose and polyphosphates) on the main pure aminopeptidases involved in the release of amino acids during the processing of cured meat products has been studied. Salt strongly inhibited alanyl aminopeptidase and pyroglutamyl aminopeptidase: about 40-50% of their original activities were recovered in the presence of 4-5% salt, the typical concentration in dry-cured meat products, while leucyl aminopeptidase was not affected. However, arginyl aminopeptidase was activated to 2-3 times its control level. Nitrate and nitrite did not affect aminopeptidase activity. Ascorbic acid (500 mg/l) slightly inhibited arginyl, alanyl and pyroglutamyl aminopeptidases whereas glucose (20 g/l) activated (to almost 5 times its control level) leucyl aminopeptidase activity. Polyphosphates inhibited (25%) alanyl and arginyl aminopeptidases.