一步样品处理测定饼干中的油脂和脂肪酸——气相色谱法

Determination of fats and their fatty acid compositionsn cookies by gas ichromatography with one-step sample pretreatment

建立了一步样品处理、气相色谱测定饼干中油脂和脂肪酸的新方法.样品、乙酰氯-甲醇和正十九烷酸甲酯的正己烷溶液,于密闭水解管中80℃水浴2h,碳酸钾溶液中和,分层后取上清液,经毛细管柱气相色谱分离,火焰离子化检测器检测.分别以测得的脂肪甲酯总量和相对分量表示样品中油脂含量和各脂脂肪酸的相对组成.结果表明,本法与索氏提取法测定的油脂含量之间无显著差异（P＜0.20）;市场采集的10个饼干样品中,油脂的含量为18.65％～38.70％,十二烷酸、肉豆蔻酸、棕榈酸、硬脂酸、油酸和亚油酸是脂肪酸组成的主体,5个样品有反式油酸检出,最高含量达总脂肪酸的23.04％.

A new method was developed for determining the content and fatty acids composition of fats in cookies by gas chromatography with one-step sample pretreatment.Cookie samples,acetyl chloride-methanol and solution of methyl nonadecanoate in hexane were sealed into a hydrolytic tubes to extract for 2h in a water bath at 80℃,then the solution was neutralized with potassium carbonate solution,and the supernatant was separated on a capillary column and detected using flame ionization detector.The content fats in samples were calculated as the sum of all fatty acid methyls esters found and the fatty acids compositions were calculated as the percentage of the corresponding fatty acids methyl esters.The results indicated that,there were no significant differences （P＜0.20） in the content fats while comparing to the results determined with Soxhlet extraction method; ten samples from market were analyzed,the contents of oils and fats were 18.65％-38.70％ the main fatty acids included odecanoic acid,tetradecanoic acid,palmitic acid,stearic acid,doleic acid and linoleic acid; elaidic acid was found in five samples,the highest level reached to 23.04％ of the fats.