Effect of different concentrations of kappa-carrageenan on gelation properties of walnut protein.

Walnut protein (WP) possesses considerable nutritional and biological value, however, the 70% water-insoluble gluten composition constrains its applicability in commercial settings. The effect of different concentrations of kappa-carrageenan (KC) on the properties of WP gels was investigated in this study. The results suggested that hydrophobic interactions are the most important force when WP/KC gels are formed. Furthermore, structural analysis revealed that KC induces notable alterations in protein molecules' secondary and tertiary structures. Moreover, the critical gelation concentration of WP decreased from 10% (w/v) to 6% (w/v) in the addition of KC. As the amount of KC increased, the rheological properties, texture properties, and physical stability of gels were enhanced. Specifically, when the addition of carrageenan increased to 2.0% (w/v), hardness increased from 25.06 g to 139.07 g, and the water-holding capacity reached 99.75%. These results provide theoretical support for the diversification of potential uses of WP/KC complexes in the plant-based protein classes.