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Sea urchin gonads (SUGs) are rich in phospholipid (PL) which is easily oxidized and hydrolyzed during cold storage. PL changes were evaluated to clarify the quality changes of sea urchins during 72 h storage at 4°C. During storage at 4°C, PL content decreased, including phosphatidylethanolamine and phosphatidylinositol content decreased significantly and lysophosphatidylcholine (LPC) was detected after 36 h storage. At the same time, phospholipase C and phospholipase D remained active, and the content of free choline and free fatty acids increased, suggesting that PL was hydrolyzed. The addition of n‐butanol inhibited the activity of phospholipases C and D, decrease of total PL content, and the production of LPC and free choline, indicating that phospholipase‐mediated hydrolysis of PL in gonads occurred during refrigeration. The addition of vitamin E inhibited lipoxygenase, reduced lipid peroxidation (POV), and thiobarbituric acid reactive substances. It indicated that lipoxygenase in SUG mediated the oxidative degradation of PL during cold storage. [ABSTRACT FROM AUTHOR]

In this study, the impact of three unsaturated fatty acids (Oleic acid: OA, Eicosapentaenoic acid: EPA, Docosahexaenoic acid: DHA) on the oxidation and structure of rainbow trout myofibrillar protein (MP) was explored. The findings revealed a notable increase in carbonyl content (P < 0.05) and a significant decrease in total sulfhydryl content (P < 0.05) of MP with the concentration increase of the three unsaturated fatty acids. Endogenous fluorescence spectroscopy and surface hydrophobicity analyses showed that unsaturated fatty acids can cause unfolding and exposure of hydrophobic groups in MP. In addition, SDS-PAGE showed that disulfide bonds were associated with MP cross-linking and aggregate size induced by unsaturated fatty acids. Overall, three unsaturated fatty acid treatments facilitated the oxidation of myofibrillar proteins, and the extent of protein oxidation was closely associated with the concentration of unsaturated fatty acids. • The relationship between MP oxidation and fatty acids in rainbow trout was revealed. • Degree of protein oxidation is dependent on the concentration of unsaturated fatty acids. • Unsaturated fatty acids induced oxidation also causes structural changes in proteins. [ABSTRACT FROM AUTHOR]