Intermolecular interactions influenced the gelation and texture improvement of sturgeon surimi gels by walnut protein isolates.

Intermolecular interaction is a key factor in the fortification of surimi gels by plant protein addition. Here, the effects of different intermolecular interactions, such as ionic, covalent and non-covalent interactions, on gel structure, gelation strength and water-holding properties were investigated, using sturgeon surimi fortified by three walnut isolates, including walnut meal (WM), protein isolate (WPI) and peptide (WP), as representatives. Quantitative creep-recovery analysis and soluble protein assay demonstrated that secondary bonds, mainly hydrophobic interaction and hydrogen bond, possibly played a dominant role in walnut protein-fortified surimi gels. Hydrophobic interaction and disulfide bond benefited gelation behavior and textural strengthening by supplementation of WM and WPI. However, 1-3 % addition of WPI and WP positively influenced water retention of surimi gels due to higher hydrogen bonding level. Structural integrity of surimi gel was not destroyed, while appropriate addition of walnut proteins especially WPI improved sensory quality of sturgeon surimi product.