蓝圆鲹传统腌干过程中内源脂肪酶和脂质降解氧化的变化分析

为探明传统腌干鱼类加工过程脂肪降解氧化规律,本研究以蓝圆鲹为原料,采用传统腌干方法,测定传统腌干鱼加工过程(鲜鱼、腌制、浸泡脱盐、烘干、成品)5个加工阶段的内源性中性脂肪酶(neutral lipase,NL)、酸性脂肪酶(acid lipase,AL)、磷脂酶(phospholipase,PL)、脂肪氧合酶(lipoxygenase,LOX)活力变化,过氧化值(peroxide value,POV)、硫代巴比妥酸值(thiobarbituric acid value,TBARS)、脂肪酸含量变化,分析内源性脂肪酶与脂质降解、氧化的关系。结果表明:蓝圆鲹腌干过程中内源性脂肪水解酶活力均随着加工进程出现不同速率的降低情况,成品中NL、AL、PL活力保存率分别为:17%、57%、33%,LOX在腌干过程中活力显著增强(P0.05)。POV和TBARS均在加工过程中逐步上升,其中POV在烘干后期急速下降。主成分分析显示内源性脂肪水解酶对脂质的降解有一定的影响作用,对脂肪氧化的影响极小;LOX对脂肪降解的影响较小,与脂质的氧化正相关;多不饱和脂肪酸含量在腌制阶段和烘干阶段呈明显下降趋势(P0.05);单不饱和脂肪酸脂肪酸和饱和脂肪酸含量均在腌制阶段和烘干阶段显著增加(P0.05);二十碳五烯酸和二十二碳六烯酸两者的含量变化呈现出互补状态。

Evoluation of Endogenous Lipase Activity,Lipolysis and Lipid Oxidation during the Processing of Traditional Dry-Salted Decapterus maruadsi

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.