Structural Characterization and Application of Oleogel-Based Soy Protein Isolate-κ-Carrageenan: a Promising Approach for Surimi Product Development

The purpose of this study was to develop a soybean protein isolate (SPI)-based oleogel to enhance the quality of surimi products. In this study, SPI-based oleogel was formulated by mixing SPI and kappa-carrageenan (kappa-CG) using an emulsion-template approach optimized by adjusting the SPI/kappa-CG ratio. The results demonstrated that the intramolecular and intermolecular hydrogen bonds between SPI and kappa-CG reinforced the three-dimensional lattice structure of the oleogels. As the increase in kappa-CG content, the oil droplets were more uniformly dispersed in the continuous SPI-kappa-CG rigid network, which formed a dense network structure and enhanced the storage modules, loss modules, recovery rate, and gel strength of the resulting oleogels. Notably, when the SPI/kappa-CG ratio was 9/1, the oleogel was dense and smooth with no oil leakage, and it exhibited the highest oil binding capacity (OBC, 94.52%) and thermal stability (412.91 degrees C). Cryo-scanning electron microscopy revealed that the oleo-surimi gel had a dense network structure, with oil droplets stably encapsulated within the surimi gel matrix by the 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 demonstrated improved. The surimi gel containing 10% oleogel exhibited the highest overall preference. This approach of making oleo-surimi gel could lead to innovation in the development of novel surimi products.