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In this study, we evaluated the effects of immersion freezing (IF) with coolant and air freezing (AF) techniques with different storage temperature (−18°C and −30°C) on the quality of groupers following frozen storage. Water loss rate, total volatile basic nitrogen, and the K-value, were positively correlated with storage time. The pH first decreased and then increased. Destruction of the muscle fiber structure led to changes in grouper texture characteristics including hardness, cohesiveness, springiness, and chewiness. IF-30°C samples retained the highest quality after frozen storage, followed by IF-18°C samples and AF-18°C samples. Immersion freezing limited protein denaturation, decreased water loss, and contributed to the formation of uniformly distributed ice crystals, decreasing microstructure damage. Immersion freezing is a promising technique for preserving the quality of groupers, and the immersion coolant (propylene glycol, oligosaccharides and salts) used in this study has potential applications in the grouper processing industry.