Ultrasound-initiated crosslinking between cod-rice dual-protein: Mechanisms underlying the development of dual-protein gel.

The combination of animal and plant proteins enables nutritional complementarity and functional synergies. This study systematically investigated the effects of different ultrasound time (0, 2, 4, 6, 8, and 10 min) on the physicochemical properties and structural characteristics of cod-rice dual-protein gel, and further explored the underlying mechanisms of gel formation. The results showed that the particle size of dual-protein system decreased from 1364.78 nm to 876.88 nm with the ultrasound treatment from 0 min (U0) to 8 min (U8), accompanied by the ζ-potential absolute value increasing. The ultrasound treatment promoted the transformation of the secondary structure of the dual-protein system to α-helix and Random. Coil, and enhanced electrostatic repulsion between molecules, which promoted the formation of uniform and dense gel network observed by tissue slice, CLSM and SEM. The densification of the network structure contributed to increase the hardness of the dual-protein gel to 40.57 g (U8). Moreover, proteomics analysis indicated that in the U8/U0 comparisons detected 189 differentially expressed proteins. Among them, the Atlantic cod myosin heavy chain (A0A8C5AHM3) was down-regulated and the rice proteasome subunit alpha type (B8AHG2) was up-regulated and, which inhibited excessive myofibril aggregation, cleaved peptides and contributed to more exposure of amino acids such as Tyr, promoting intermolecular cross-linking. However, excessive ultrasound time (10 min) caused the dual-protein gel network to become loose, leading to the hardness of U10 decreasing to 33.95 g. By synthesizing findings, this research provides a theoretical basis for the development of dual-protein gel foods.