Molecular Mechanisms Involved in Thermally Induced Gel Formation of Japanese Codling Meat Paste during a Two-Step Heating Procedure

We analyzed changes in the rheological properties of Japanese codling (Physiculus japonicus) meat paste during the following two-step heating procedure: first preheating at 0–70 °C with 5 or 10 °C intervals and subsequent secondary main heating at 85 °C. Changes in the breaking strength and breaking strain rate showed roughly three phases associated with preheating temperatures of 0–25, 30–50, and 55–70 °C. The most prominent change was observed for preheated gels with preheating from 30 to 55 °C, where the myosin polymerization rate was high. The increase in the preheating temperature from 0 to 25 °C was accompanied by a gradual decrease in protein solubilization and a rapid increase in myosin polymerization for preheated gels, suggesting that gel formation occurred even at low preheating temperatures. Dynamic viscoelasticity measurements indicated that structural changes in myosin other than polymerization also participate in gel formation. Moreover, NH4Cl, an inhibitor of transglutaminase, reduced myosin polymerization in meat paste.