Enhanced antioxidant activity of low-molecular-weight hyaluronan-based coatings amended with EGCG for Torreya grandis kernels preservation

Polysaccharide coating protection technology has always been a research hotspot in the field of food preservation. In this study, hyaluronic acid (HA), the widely used green polysaccharide was optimized by a free radical mediated method for covalent grafting high antioxidant epigallocatechin gallate (EGCG) to prepare copolymers (HA-EGCG) and applied to the preservation of Torreya grandis kernels. The physicochemical properties, antioxidant activities and application effect of HA-EGCG were investigated. The results found that low-molecular-weight HA (LHA) could obtain a higher grafting rate than high-molecular-weight HA (HHA), reaching 93.5 %. For structural character, the LHA-EGCG showed good stablility, which improved the surface roughness of the edible coating and the addition of EGCG significantly enhanced the antioxidant activities ( p  < 0.01). For application effect, LHA-EGCG coating significantly inhibit the change of appearance color, and increase of malonaldehyde, acid value, and peroxide value during long-term storage of T. grandis kernels, and could maintain its flavor to prolong quality retention. Collectively, the edible coating of HA grafted EGCG significantly prolong the quality of the kernel and has broad application potential in the field of food preservation.