Impact of plant and animal proteins with transglutaminase on the gelation properties of clam Meretrix meretrix surimi

Abstract

Different sources of proteins have various ways for facilitating the gelation process of surimi matrices, leading to the diverse combined effects with transglutaminase (TG). In this study, the effects of two plant proteins, soy protein isolate (SPI) and pea protein isolate (PPI), and two animal non-muscle proteins, egg white protein (EWP) and whey protein isolate (WPI), with TG addition on the gel properties of clam Meretrix meretrix (MM) surimi gels were investigated, and the mechanisms were explored. In the presence of TG, the exogenous protein addition significantly improved (p < 0.05) the gelation process of the MM surimi. The best improvements were obtained with the combination of EWP, where the gel strength, cooking loss, and water holding capacity were enhanced by 113.08%, 67.89%, and 26.30%, respectively. The addition of SPI showed a relatively weak enhancement compared to EWP incorporation, followed by the addition of PPI and WPI. The results of optical microscopy, differential scanning calorimetry, and chemical forces demonstrated that TG preferentially promoted plant proteins to form self-aggregation in the surimi system, and SPI generated more polymers than PPI. In contrast, the interpenetration of animal proteins and MM myofibrillar proteins was improved by TG. EWP formed a double cross-linking network within the MM protein network, while WPI acted as a binder to promote protein-protein interactions. This research could provide novel insights for developing MM resources and establish a theoretical foundation for the use of composite exogenous protein additives to enhance the gel properties of MM surimi products.