Abstract: In order to improve the quality of frozen-thawed horse mackerel, frozen fish were thawed by five different methods (refrigerator thawing, ?owing water thawing, ultrasonic-assisted flowing water thawing, ultrasonic-assisted still water thawing and microwave thawing) in this study, and the changes in physicochemical indicators including water-holding capacity, color, texture, metmyoglobin (MetMb) content, malondialdehyde (MDA) content, total sulfhydryl content and protein tertiary structure were analyzed. The water mobility in fish was investigated by pulsed nuclear magnetic resonance spectroscopy, and the microstructure of fish tissue was observed by optical microscopy. The results showed that frozen fish maintained good water-holding capacity and color after refrigerator thawing, and its muscle tissue remained intact to the greatest extent. Refrigerator thawing could effectively alleviate the oxidation of protein and fat, but was the most time-consuming. Ultrasonic-assisted flowing water thawing was completed within 10 minutes, being suitable for large-scale thawing. Compared with the other thawing methods except refrigerator thawing, ultrasonic-assisted flowing water thawing could effectively slow down the oxidation of fish protein and fat, and better maintain the quality of fish.

Key words: horse mackerel; thawing method; ultrasonic-assisted flowing water thawing; freezing-thawing; quality