Oxidation of aquatic products from the inside out accelerates their deterioration: A case study of sea bass (Lateolabrax japonicus) during storage

Sea bass ( Lateolabrax japonicus ) is favored by consumers, but the oxidation of visceral lipids during refrigeration has not been studied. This research investigates the effect of visceral lipid oxidation on storage quality. The results show that visceral lipids oxidize first, leading to a 1.72, 2.36, and 2.04-fold increase in malondialdehyde, 4-hydroxy-2-nonenal, and 4-hydroxy-2-hexenal levels, respectively. The total free radicals, alkoxy radicals, and hydrogen radicals increased by 18.13 %, 18.17 %, and 9.87 %, respectively. Visceral lipid oxidation damages myofibrillar proteins, reducing sulfhydryl content by 18.11 %. The viscera also promote protein oxidation, particularly of actin. Volatile component and electronic nose analyses revealed significant odor deterioration due to lipid oxidation and protein degradation. Molecular docking confirms that 4-hydroxy-2-nonenal binds to 15 amino acids in β-actin. Therefore, spoilage occurs from the inside out, and viscera should be removed before freezing.