Abstract: In order to figure out the evolution of lipolysis and lipid oxidation during the processing of traditional dry-salted Decapterus maruadsi, the changes in neutral lipase (NL), acidic lipase (AL), phospholipase (PL), lipoxygenase (LOX), thiobarbituric acid reactive substance value (TBARS), peroxide value (POV), and lipid composition were measured and the correlation of endogenous lipase activity with lipid degradation and oxidation was analyzed at five processing stages, i.e., fresh fish, salting, soaking desalting, drying and final product. The results showed that neutral lipase, acid lipase, phospholipase activities markedly decreased (P < 0.05) during the whole process, and only 17%, 57%, 33% of the initial activity was retained in the final product, respectively. LOX activity increased significantly during the whole process (P < 0.05), and both POV and TBARS increase except for a significant decrease in POV during the late stage of drying. As evaluated by principal component analysis, the activities of endogenous fat hydrolases (NL, AL and PL) had a significant effect on lipid degradation, but a rather limited effect on lipid oxidation. LOX activity was positively related to lipid oxidation but it was little related to lipolysis. During both salting and drying polyunsaturated fatty acids (PUFA) revealed a significant decrease (P < 0.05), but monounsaturated fatty acids (MUFA) and saturated fatty acid (SFA) revealed a significant increase (P < 0.05). The contents of both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exhibit a complementary relationship.

Key words: Decapterus maruadsi, traditional dry-salted fish, endogenous lipase, lipolysis and lipid oxidation