Chlorogenic acid-grafted chitosan as a natural cryoprotectant preserves the quality and myofibrillar protein stability of pork patties during repeated freeze-thaw cycles.

Repeated freeze-thaw (F-T) cycles during cold-chain storage severely deteriorate the quality of minced meat products. This study evaluated the cryoprotective efficacy of chlorogenic acid-grafted chitosan (CA-g-CH) on the quality stability and structural integrity of myofibrillar proteins (MPs) in pork patties. Pork patties supplemented with 0%, 0.3%, 0.6%, or 0.9% (w/w) CA-g-CH were subjected to six F-T cycles, and their physicochemical quality, water mobility, texture, rheological properties, lipid and protein oxidation, microstructure, and MP conformation were systematically evaluated. CA-g-CH exerted concentration-dependent protective effects, with the 0.9% addition showing the best performance. After six F-T cycles, compared with the control, the 0.9% CA-g-CH treatment reduced thawing drip loss and expressible moisture, decreased TBARS values by 57.4% and protein carbonyl content by 39.5%, and retained 73.3% more total sulfhydryl groups. It also restricted the migration of immobilized water (P21) to free water (P22), mitigated the F-T-induced loss of α-helical content, and maintained higher denaturation temperatures and enthalpies of myosin and actin, thereby preserving the gelation capacity and textural stability of the patties. These effects are likely attributed to the ice-binding capacity of the chitosan backbone, non-covalent interactions between CA-g-CH and MPs, and the potent radical-scavenging activity of the grafted chlorogenic acid. CA-g-CH is a promising natural cryoprotectant for stabilizing MP structure and maintaining the overall quality of pork patties during repeated F-T cycles.