Effect of succinylated gelatin on transglutaminase-catalyzed gel network formation

The melting and gelation temperatures of gelatin, as well as its transglutaminase (TGase)-catalyzed gelation capacity, collectively determine its functional properties in food systems. However, the relatively high gelation temperature of mammalian gelatin restricts its applicability in low-temperature processing scenarios, such as those involving meat, poultry, aquatic products, and soy-based formulations. Succinylation represents a promising approach for modifying gelatin properties; nonetheless, its influence on the glutamine TGase-catalyzed gelation reaction, particularly within low-temperature plant-protein hybridization systems, remains inadequately understood. This knowledge gap limits the ability to conduct functional design and optimization of food products.

Increasing succinic anhydride (5-300 mg g^-1 gelatin) reduced gelatin's gelation/melting temperatures. Notably, when anhydride addition exceeded 45 mg g^-1, nearly complete elimination of ε-amino groups in lysine residues was observed. Despite the absence of ε-amino groups, which are a substrate for TGase, the succinylated gelatin demonstrated a remarkable capacity to enhance TGase-catalyzed crosslinking with soy protein under low-temperature conditions, with the G-C100 group exhibiting 1.2-fold greater gel strength than that of the control. Mechanistic analysis suggested that glutamine residues remain accessible as crosslinking sites for TGase, while the reduced helix structure increases the conformational flexibility of succinylated gelatin chains.

This research establishes a theoretical foundation for developing functional foods based on gelatin-plant-protein composite systems, particularly for low-temperature gelation applications. © 2025 Society of Chemical Industry.