Effects of polysaccharides and soy protein isolate on the gel properties and molecular structure of squid (Dosidicus gigas) surimi.

Abstract

Background: Squid has characterized by high protein, low fat and no intermuscular bones, which makes it an ideal raw material for making surimi. However, the gel quality of squid surimi is inferior because of its high endogenous enzyme activity and low content of myosin and transglutaminase, which makes myofibrillar protein easy to be degraded and the degree of cross-linking of myosin heavy chain low. Although the cost of starch is low, its addition may lead to the reduction of protein content and the increase of heat of the gel product, and excessive addition may even reduce the quality of the product. Therefore, it is necessary to find additives with clean labels.

Results: The present study determined the optimal formulation for squid surimi gel as 6 g kg^-1 inulin (IN), 8 g kg^-1 sodium alginate (SA), and 60 g kg^-1 soy protein isolate (SPI) through orthogonal testing. The combination achieved a water-holding capacity of 90.28% and gel strength of 1592.78 g·mm, which is significantly higher than that of the traditional starch modification system. The transition from α-helix to β-sheet conformation enhanced hydrophobic interactions, whereas SPI acted as a molecular scaffold synergizing with IN-SA complexes to stabilize the gel network through hydrogen bonding and electrostatic bridging, yielding a dense microstructure.

Conclusion: In conclusion, this starch-free strategy, with its superior functionality and clean label benefits, provides an innovative approach for the development of sustainable aquatic gel products and an important opportunity to further understand the mechanism by which polysaccharides and SPI influence the gel properties of squid surimi. © 2025 Society of Chemical Industry.