Chitosan grafted gallic acid /polyvinyl alcohol-based hydrogel, developed through the freeze-thaw method, holds promise for use as a fresh-water absorbent pad.

In this research, gallic acid was initially grafted onto chitosan using the carbodiimide grafting technique. Subsequently, PVA/CS-GA (PCG) hydrogels were synthesized through a process combining polyvinyl alcohol with repeated freeze-thaw cycles. The physicochemical properties of hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), compression mechanics test, tensile test, and rheology. Finally, the preservative application of sea bass (Lateolabrax maculatus) fillet was studied by pH, TVB-N, and sensory evaluation. The results of FTIR confirmed that CS-GA is effectively integrated into the PVA network. Scanning electron microscopy results showed that the prepared PCG11 and PCG12 hydrogels possessed porous structure, high water content, excellent water absorption, swelling and rheological properties. In addition, it was found that PCG12 hydrogels had the strongest antioxidant and antibacterial properties. Meanwhile, in the freshness preservation experiments, it was found that PCG 11 hydrogel and PCG12 hydrogel could effectively extend the shelf life of sea bass. In general, PCG hydrogels are a potential packaging material for food.