Ultrasound-assisted citric acid treatment mitigates oxidative deterioration of oysters during frozen storage.

This study investigated the effects of ultrasound-assisted citric acid (US+CA) treatments on the quality stability of oysters during frozen storage. Results showed that freezing induced pronounced deterioration in color, texture, water-holding capacity, and freshness, accompanied by lipid and protein oxidation. CA pretreatment partially alleviated these changes, while ultrasound further enhanced preservation efficacy. Among the tested conditions, US200+CA exhibited the best protective effect, maintaining physicochemical properties and suppressing volatile off-flavor formation and TVB-N accumulation. Lipidomic analysis showed improved retention of membrane phospholipids and polyunsaturated fatty acids, alongside reduced lipid oxidation. Similarly, protein oxidation markers, including carbonyls, Schiff bases, dityrosine, and disulfide bonds, were significantly reduced. Proteomic analysis revealed reduced oxidation frequency and fragmentation of key myofibrillar and cytoskeletal proteins under US+CA treatment. Overall, moderate ultrasound enhanced the antioxidant effectiveness of CA by coordinately regulating lipid and protein stability, providing mechanistic insight into oxidative control strategies for frozen oyster preservation.