Effect of Storage Temperature on Changes in Gel Strength and Myofibrillar Protein of Pressure-induced Gel of Walleye Pollack Surimi

Frozen surimi of walleye pollack was ground with 2.5% NaCl and treated under a high hydrostatic pressure of 300 MPa at 0°C for 10min. The pressure-induced gel thus formed was subsequently stored at 5, 15, and 25°C. During storage, changes in breaking strength and breaking strain, and the subunit composition of myofibrillar protein of the gel were examined. It was found that (1) breaking strength of the gel increased with the lapse of storage time at every temperature, and the maximum values were much larger compared to that of non-pressure-treated gel. (2) When the pressure-induced gel was stored at 5°C, the breaking strength increased slowly, and reached its highest value. (3) During the increase in breaking strength, myofibrillar protein changed together with a decrease in myosin heavy chain (HC) and an increase in HC polymers (namely HCn, HCn', and HCn" by T. Numakura et al.) (4) of these HC polymers, HCn" (SDS-urea medium-insoluble, the largest molecular component), was formed in a large quantity of the pressure-induced gel compared to that of non-pressure-treated gel. These results strongly suggested that pressure-treatment of salt-ground meat caused conformational change of myofibrillar protein of surimi. Thus, the quality of pressure-induced gel was able to be controlled not only by the condi-tions for pressure-treatment but also by subsequent storing conditions.