3种海洋鱼油脂肪酸组成及其位置分布

Composition and positional distribution of fatty acids in triacylglycerols of three marine fish oils

采用米黑根毛霉源固定化脂肪酶(Lipozyme RM IM)对常见的海洋鱼油甘三脂进行水解,分析了凤尾鱼、金枪鱼、三文鱼甘三酯中脂肪酸的组成及位置分布。采用硅胶色谱柱分离3种海洋鱼油甘三脂,利用Lipozyme RM IM的sn-1,3特异性,将酯化在sn-1,3位上的脂肪酸(EFA)水解成游离脂肪酸(FFA),然后通过薄层层析(TLC)分离得到sn-2-单甘酯,再甲酯化后利用气相色谱(GC)测定sn-2位脂肪酸组成,并按照脂肪酸的不饱和程度和n-3,6-多不饱和脂肪酸归类分析海洋鱼油甘三酯中各类脂肪酸位置分布的特点。结果表明:3种海洋鱼油(凤尾鱼油、金枪鱼油、三文鱼油)中不饱和脂肪酸含量达到60%以上,其中单不饱和脂肪酸(MUFA)占24.67%~33.51%,多不饱和脂肪酸(PUFA)占26.89%~36.15%,而且一半以上PUFA分布在sn-2位,有利于其吸收和提高其耐氧化性;而SFA和MUFA倾向于分布在sn-1,3位上。n-3与n-6PUFAs之间的比例均>10,均符合FAO/WHO推荐摄入的标准(>4),是理想的n-3PUFA天然营养补充剂。

In this study,the purified triacylglycerols（TAG）of selected marine fish oils（anchovy,tuna and salmon oils） were subjected to stereospecific hydrolysis by an sn-1,3-specific lipase（Lipozyme RM IM）which cleaves selectively the sn-1 and sn-3 position ester bonds of TAG yielding to sn-2-monoglycerides（2-MAG）.After lipase hydrolysis,the released free fatty acids and sn-2-MAG were isolated by thin-layer chromatography（TLC）.The original TAG and sn-2-MAG were respectively converted to fatty acid methyl esters（FAME）,then analyzed by gas chromatography（GC）.Results showed that TAG of these marine fish oils were made up of unsaturated fatty acids mainly accounting for 60%.Polyunsaturated fatty acids are preferentially located at sn-2 position,whose percentage is more than 50%,while saturated fatty acids and monounsaturated fatty acids are most distributed in sn-1,3 position.The ratio between n-3 and n-6 PUFAs is greater than 10,which is in line with the FAO/WHO recommended intake standard（〉4）and is ideal for n-3 PUFA natural nutritional supplements.