THE PH-DEPENDENCE OF CHANGES IN GEL FORMING ABILITY AND MYOSIN HEAVY-CHAIN OF SALT-GROUND MEAT FROM WALLEYE POLLACK

Frozen surimi from walleye pollack was ground with 2.5% NaCl at various pHs in a range of 5,76 approximately 8.40, which were fixed by addition of dilute HCl or NaOH. During setting of the salt-ground meat at 25-degrees-C, breaking strength and breaking strain were investigated as a function of time. With the lapse of setting time, the breaking strength and breaking strain of the salt-ground meat both rapidly increased and reached their maximum plateau. The highest value was exhibited at pH 7.35 for the breaking strength and pH 6.5 approximately 7.6 for the breaking strain. The breaking strength and breaking strain both decreased with failing or rising of the pH from these values. The mode and rate of cross-linking reaction of myosin heavy chain (HC) of the salt-ground meat depended notably on the pH for setting. At acidic pH, a large decrease in the amount of HC was accompanied by the formation of a relatively scarce amount of cross-linked myosin heavy chain (SIGMA-HC(n)=HC(n)+HC(n)'+HC(n)'') and unidentified components. In contrast, the decrease in HC with concomitant formation of SIGMA-HC(n) were both suppressed under alkaline pH. These results indicated that a neutral pH of the salt-ground meat was essential for the formation of SIGMA-HC(n) in large quantities and a resulting contribution to elastic gel.