Hydrolysis-crosslinking coupled structural reconstruction to improve the textural properties of thermally stable collagen hydrogels.

Transglutaminase (TGase)-induced high density isopeptide crosslinking enables thermally irreversible collagen hydrogels suitable for high temperature sterilization, but makes them overly elastic and difficult to chew, resulting in poor palatability. This study reconstructed the collagen molecular conformation via a sequential pre-hydrolysis and crosslinking approach, elucidating the mechanisms of texture modulation. Results indicated that 20-60 min of papain pre-hydrolysis reduced colloidal particle sizes, shortened molecular chains, and weakened stabilizing hydrogen bonds, while preserving basic triple-helical self-assembly capabilities. After crosslinking, an extended pre-hydrolysis time yielded shorter triple-helices and weaker maintaining hydrogen bonds, progressively prolonging the gelation time. Increasing the pre-hydrolysis degree reduced the effective crosslinking density and elevated molecular flexibility, fostering a more uniform microstructure during gel shrinkage and enhancing collagen-water interactions. These structural modifications ultimately decreased the elasticity and deformation resistance of the hydrogels, effectively improving their overall textural properties and sensory acceptability.