高分辨率反式脂肪酸测定方法的建立及市售食用油反式脂肪酸的测定

本文建立了高分辨率的反式脂肪酸测定方法,并考察了市售食用油的反式脂肪酸含量及其种类的情况。结果表明:采用高极性的色谱柱HP-88在优化后色谱条件下,可以实现4种亚油酸异构体、8种亚麻酸异构体、37种常见脂肪酸良好的色谱分离,而且反式脂肪酸与常见的顺式脂肪酸在同时检测条件下出峰时间不重叠,可以进行高分辨率的脂肪酸包括反式脂肪酸组成分析;市售主要品种的食用油都存在一定量的反式脂肪酸,其中调和油、花生油、大豆油含有2~3%的反式脂肪酸(反式亚麻酸含量在1.5~2%之间);玉米油和葵花籽油中反式亚油酸的含量在0.7~2%之间;稻米油的反式脂肪酸的含量最高,接近4%;橄榄油和山茶油的反式脂肪酸含量一般在0.5%以下;各油样的反式脂肪酸异构体的种类也存在区别。

Development and Application of a High-resolution Method to Determine Trans Fatty Acids in Commercially Available Edible Oil

A high resolution method to determine trans fatty acids was established, and was used to examine the content and types of trans fatty acids in commercially available edible oil. Good chromatographic separation of four trans linoleic acid isomers, eight trans linolenic acid isomers, and 37 common fatty acids could be achieved using a high-polarity HP-88 gas chromatography (GC) column under optimized chromatographic conditions. Moreover, the peaks of trans fatty acids and common cis fatty acids did not overlap in the same detection conditions; thus, a high-resolution analysis of fatty acid (including trans fatty acid) composition was possible. The main brands of commercially available edible oil products all contain trans fatty acids. Blended oil, peanut oil, and soybean oil contained 2~3% trans fatty acids (the trans linolenic acid content was between 1.5~2%); corn oil and sunflower oil contained 0.7~2% trans linoleic acid; rice oil contained the highest trans fatty acid content, close to 4%. Additionally, the trans fatty acid content in camellia oil and olive oil were generally below 0.5%. The types of trans fatty acid isomers in each oil sample also differed.