Autolysis study of bigeye snapper (Priacanthus macracanthus) skin and its effect on gelatin

Autolysis of bigeye snapper (Priacanthus macracanthus) skin was studied. The maximal autolytic activity was observed at 60 degrees C and pH 7.5. The proteolytic activity was strongly inhibited by 0.001 mM soybean trypsin inhibitor (SBTI), whereas pepstatin A (1 mu M), EDTA (20 mM), EGTA (10 mM), iodoacetic acid (1 mM), PMSF (1 mM), E-64 (10 mu M) and 1,10-phenanthroline (1 mM) showed no inhibitory effect. The result suggests that the major proteinase in bigeye snapper skin was a serine proteinase. Gelatin was extracted from bigeye snapper skin in water without and with 0.001 mM SBTI using a skin/water ratio of 1:7 at different temperatures (35, 40, 45, 50, 55 and 60 degrees C) for 12 h. In the presence of SBTI, the degradation was markedly inhibited. However, beta-chain disappeared and a-chains underwent degradation to some extent at temperatures above 50 degrees C. Generally, a higher yield of gelatin was obtained as the extracting temperature increased (P < 0.05). Nevertheless, the addition of 0.001 mM SBTI caused a lower gelatin yield. Therefore, heat-activated serine proteinase, most likely collagenase, involved in the degradation of collagen molecule and affected the yield and proteinaceous components in the resulting gelatin from bigeye snapper skin. (c) 2006 Elsevier Ltd. All rights reserved.