EFFECTS OF BAMBARA GROUNDNUT PROTEIN ISOLATE ON PROTEIN DEGRADATION AND GEL PROPERTIES OF SURIMI FROM SARDINE (SARDINELLA ALBELLA)

ABSTRACT Effects of protein isolate from bambara groundnut (BGPI) at different levels (0–1.5%) on autolysis and gel property of surimi from sardine (Sardinella albella) were investigated. Higher inhibitory activity against autolysis for kamaboko (40/90C) and modori (65/90C) gels was observed when BGPI level increased up to 1%. BGPI effectively prevented the degradation of myosin heavy chain in a concentration-dependent manner in both gels. This was associated with the increased breaking force and deformation of gels added with BGPI (P < 0.05). Water-holding capacity of gels was improved with increasing level of BGPI incorporated (P < 0.05). However, whiteness of kamaboko and modori gels slightly decreased with increasing BGPI levels (P < 0.05). Microstructure of kamaboko and modori gels added with 1% BGPI had the denser and more ordered fibrillar structure, indicating a preventive effect of BGPI on hydrolysis of myofibrillar proteins. PRACTICAL APPLICATIONS Surimi from dark-fleshed fish is generally prone to protein degradation caused by heat-activated proteases. Proteolytic disintegration of myofibrillar proteins leads to gel weakening of surimi. Gel-forming ability of myofibrillar proteins is the most important functional requirement to provide the superior quality of surimi-based products. Protein isolate from bambara groundnut (BGPI) containing protease inhibitors could be used to lower autolysis of sardine surimi caused by endogenous proteases. In addition, BGPI might serve as a co-gelling agent or binder in surimi gels. Thus, BGPI could be used as the promising protein additive for surimi industry.