Structural Characterization and Application of Crosslinked Soybean Protein Isolate-Based Oleogel Containing κ-Carrageenan: A Promising Approach for Surimi Product Development

Abstract In this study, Soybean Isolate Protein (SPI) based oleogel was constructed by mixing SPI and κ-Carrageenan (κ-CG) using an emulsion-template approach optimized by adjusting SPI/κ-CG ratio. The results demonstrated that the intramolecular and intermolecular hydrogen-bonds between SPI and κ-CG reinforced three-dimensional lattice structure of the oleogels. With the increase of κ-CG content, the oil droplets were more uniformly dispersed in the continuous SPI-κ-CG rigid network, which formed a dense network structure and improved the storage module, loss module, recovery rate, and gel strength of the resulting oleogels. In particular, when the SPI/κ-CG ratio was 9/1, the oleogel was dense and delicate with no oil leakage. This formulation also showed the highest oil binding capacity (OBC, 94.52%) and thermal stability (412.91 ℃). Cryo-scanning electron microscopy showed that the oleo-surimi gel had a dense network structure, and the oil droplets were stably encapsulated in the surimi gel matrix by polysaccharide-protein interfacial membrane. Compared with surimi gel made with the direct addition of liquid oil, the water-holding capacity and textural properties of oleo-surimi gel were effectively improved. The approach of making oleo-surimi gel could lead to innovation in the development of novel surimi products.