Dual-functional tannic acid synergistically reinforces the mechanical strength and antimicrobial activity of gelatin/polyvinyl alcohol hydrogels for strawberry preservation.

Hydrogels have great application potential for food preservation due to their excellent biocompatibility and functional tunability, but it is difficult to easily balance mechanical strength and functionality. In the present study, gelatine (Gel) and polyvinyl alcohol (PVA) were used as substrates, and tannic acid (TA) was introduced to construct a composite hydrogel by freezing-salting out method. The mechanical, antimicrobial, and strawberry preservation performance of TA-loaded hydrogels was systematically evaluated. The results revealed that freeze-salting out promoted hydrogen bonding crosslinking and physical entanglement between PVA and Gel chains, while TA further optimized the microstructure through intermolecular interactions. Specifically, the hydrogel with 10% TA (GP10T) was identified as the optimal formulation. It achieved a compressive strength of 7.74 MPa, a Young's modulus of 1.04 MPa, and an energy dissipation rate of 29.14%. Rheological analysis revealed a gel-sol transition point delayed to approximately 900% strain. Additionally, it exhibited an equilibrium swelling ratio of 137.36% and a controlled degradation rate of 72.82% within 30 days. The GP10T hydrogel inhibited the growth of Botrytis cinerea and effectively maintained the firmness, color and other quality parameters of strawberries during storage. The developed GP10T hydrogel shows promising prospects for fruit preservation applications.