Contribution of Retained Organ Tissues to the Alkaline Protease Content of Mechanically Separated Atlantic Croaker (Micropogon undulatus)

Abstract

ABSTRACTThe greater texture breakdown observed in gel‐type products prepared from mechanically separated tissue as opposed to manually separated tissue can to some extent be attributed to the significantly higher protease activity measured in mechanically separated tissue. Failure to thoroughly wash eviscerated fish prior to mincing appears to result in the retention of tissue from internal organs as evidenced by a concommitant increase in protease activity in the minced tissue. Alkaline protease activity in croaker kidney and liver is several thousand fold higher than in skeletal muscle. Addition of kidney and liver tissue to deboned tissue from thoroughly washed fish results in increased protease activity and degradation of the fish tissue upon comminuting and cooking at 60°C. Isoelectric focusing provided evidence that the increased alkaline protease activity observed in mechanically separated fish tissue resulted to some degree from retention of kidney tissue in the fish mince. Isolation of Ca++‐dependent protease fractions from liver also implicated contamination from this source as an additional contribution to the total protease activity of minced fish.