Combining effect of soybean protein isolate and transglutaminase on the gel properties of Zhikong scallop (Chlamys Farreri) adductor muscle

The effects of soy protein isolate (SPI) in combination with transglutaminase (TGase) on the gel properties of Zhikong scallop (Chlamys farreri) adductor muscle were investigated. When 4 g/100 g SPI combined with 0.4 g/100 g TGase were added, the gel strength and water holding capacity (WHC) of heat induced Zhikong scallop adductor muscle gel was significantly improved. The textural profiles, such as hardness, cohesiveness, springiness and chewiness, reached their peaks as well. Although the whiteness continued to decrease with the increase of SPI content, TGase did not influence the whiteness of Zhikong scallop adductor muscle gel regardless of SPI levels. According to the results of LF-NMR, the free water was transformed into bound and immobilized water in gels containing SPI and/or TGase. SDS-PAGE showed that TGase would promote the cross-linking of SPI and Zhikong scallop adductor muscle protein, and offset the negative effects of excessive SPI. Further optical microscopy and SEM observed that the formation of the most compact network structure, which was caused by more inter- and intra-molecular cross-linking of proteins. The results suggested that the addition of 4 g/100 g SPI combined with 0.4 g/100 g TGase could effectively improve the gel properties of Zhikong scallop adductor muscle.