EFFECT OF ULTRASONIC TREATMENT ON THE ACTIVITIES OF ENDOGENOUS TRANSGLUTAMINASE AND PROTEINASES IN TILAPIA (SAROTHERODON NILOTICA) SURIMI DURING GEL FORMATION

Abstract

ABSTRACTThe effects of ultrasonic treatment (UT) on the activities of endogenous transglutaminase (TGase) and proteinases in tilapia surimi were investigated. Surimi paste set at 40C with or without UT, prior to heating at 90C, resulted in a significant (P < 0.05) increase in gel strength as setting time increased, the gel strength of surimi paste treated with UT was higher (P < 0.05) than that of the control. A decrease in the solubility of surimi gels with UT suggested that the UT increased the formation of non‐disulfide covalent bonding which coincided with an increase in gel strength and a decrease in myosin heavy chain (MHC) polypeptide content. Surimi paste incubated at 65C with UT prior to heating at 90C resulted in a significant increase in gel strength (P < 0.05), compared with the control. A decrease in the trichloroacetic acid‐soluble peptides of surimi gels with UT coincided with an increase in gel strength and more retained MHC, suggesting that the endogenous proteinases were deactivated by UT.PRACTICAL APPLICATIONGel strength is important for the quality of surimi gel. Ultrasonic treatment (UT) was used to treat surimi sol when it was setting at 40C, the result showed that UT could increase the gel strength of tilapia surimi. In order to find the possible reason for the increase of gel strength as a result of UT, effect of UT on the activities of endogenous enzymes in tilapia was investigated. This will inspire the surimi product producers to improve the gel strength of surimi by using UT instead of adding food additives. UT can supply one new method of processing surimi product. This can obviate the potential danger brought by unsuitable addition of food additives.