The effect of carrageenan oligosaccharides on the muscle quality and myofibrillar protein stability of sea bass (Lateolabrax japonicus) during freezing storage under different freezing methods.

Frozen storage is widely used for the preservation of seafood quality, but protein denaturation and oxidative damage often lead to a decline in fish meat quality. This study investigated the effects of carrageenan oligosaccharides combined with different freezing treatments on the muscle quality and myofibrillar protein stability of sea bass (Lateolabrax japonicus) during 8 weeks of frozen storage. The results showed that the meat quality of fish stored after carrageenan oligosaccharide treatment was superior to that of the untreated group. Carrageenan oligosaccharides effectively alleviated quality deterioration, particularly when combined with the quick-freezing treatment. After 8 weeks, this combined treatment maintained the highest water hold capacity (79.70%) and the lowest cooking loss (21.69%), indicating improved water retention. It also maintained the highest myofibrillar protein solubility (77.96%) and Ca2+-ATPase activity (1.703 μmolPi/mg protein/h), retained a higher total sulfhydryl content (5.49 mol/105 g pro), and showed the lowest surface hydrophobicity (30.09). These changes were accompanied by reduced water migration, muscle structural deterioration, protein unfolding, oxidation, and aggregation. Raman spectroscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis further demonstrated better preservation of protein secondary structure and myosin integrity after frozen storage. Molecular docking indicated that carrageenan oligosaccharides interacted with myosin mainly through hydrogen bonding and electrostatic interactions involving hydroxyl and sulfate groups. This study provides new insights into maintaining muscle quality and myofibrillar protein stability during frozen storage.