Effects of Bambara Groundnut Protein Isolate on Protein Degradation and Gel Properties of Surimi From Sardine (Sardinella Albella)

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.