巧克力中脂肪酸组成及反式脂肪酸含量的分析

摘要

目的：建立测定巧克力中脂肪酸组成和反式脂肪酸含量的气相色谱方法。方法采用氢氧化钾-甲醇甲酯化方法，将甘油三酯转化为脂肪酸甲酯，并使用气相色谱-氢火焰离子化检测器进行分析。结果以三油酸甘油三酯为模型化合物，确定甲酯化效率为99.8%。使用面积归一化定量方法，对市面上不同品牌、不同种类的5种巧克力进行分析。巧克力油脂中主要脂肪酸为棕榈酸、硬脂酸和油酸，含量范围分别为：25%~27%、32%~35%及30%~32%；反式脂肪酸含量范围为0.4%~1.1%(以油脂中含量计)。结论该方法简单快速，适合巧克力油脂中脂肪酸组成和反式脂肪酸含量的分析。%Objective To build testing method for analyzing the fatty acid composition and thetrans-fatty acids content in chocolate.MethodsBased on the esterification method of potassuim hydroxide-methanol, the triglycerides were transferred to fatty acid methyl esters, which were analyzed by gas chromatography/ flame ionization detector (GC/FID).Results With glycerol trioleate as research model, the esterification efficiency was determined to be about 99.8%. With the quantitation method with area normalization, 5 chocolate samples with different brands and different varieties were tested, it showed that palmitic acid, stearic acid and oleic acid were the 3 main fatty acids in chocolate, and their content were 25%~27%, 32%~35% and 30%~32% respectively. Besides, the amount of tans-fatty acids ranged from 0.4% to 1.1% in chocolate. Conclusion The developed method was easy to implement and could be applied to the fatty acid analysis in chocolate.