Deterioration of white croaker (Pennahia argentata) meat thermally-induced gel products caused by proteolytic enzymes in the contaminated intestine and kidney

Thermally-induced gels were made from white croaker (Pennahia argentata) meat in the presence of its organ extracts by pre-heating at 40 and 65 °C for 20 min and subsequent heating at 85 °C for 20 min. The breaking strength of the gels decreased with increasing concentrations of the intestinal extracts accompanying decomposition of myosin heavy chains. However, no significant changes in the gel strength occurred when the kidney extract was added. The proteolytic activity in the intestinal extracts examined in the meat homogenate had a maximum at 60 °C and pH 8.90. These results suggest that the intestinal rather than kidney proteolytic activities are responsible for gel softening known as a modori phenomenon. Thus, the removal of intestinal tracts is essential to maintain a high quality of surimi-based products.