Effects of ultrasound-assisted immersion freezing on the muscle quality and myofibrillar protein oxidation and denaturation in Sciaenops ocellatus

Freezing is a method that plays a key role in the storage of aquatic products. The effects of different methods of freezing on the quality, microstructure, ice-crystal morphology, and protein oxidation of Sciaenops ocellatus were investigated. Air freezing (AF), immersion freezing (IF), and different powers of ultrasound-assisted immersion freezing (UIF) (150, 200, and 250 W) were studied. IF and UIF significantly improved the freezing rate of S. ocellatus and shortened the freezing time by more than 83% compared with AF. The freezing rate achieved using UIF (200 W) was 712.81% higher than that achieved using AF. Oxidative denaturation of the myofibrillar protein was reduced after 90 days of frozen storage. Moreover, frozen samples in the UIF-200 W group had higher protein stability compared with that in the other groups. Therefore, appropriate ultrasonic power (200 W) during freezing can accelerate the freezing process of S. ocellatus and maintain its muscle quality.