3种前处理方法处理婴幼儿配方奶粉中二十二碳六烯酸、花生四烯酸、亚油酸和α-亚麻酸的差异性

探讨了国家标准GB 5009.168-2016中乙酰氯-甲醇甲酯化法、酸水解酯化法和碱水解酯化法3种前处理手段处理婴幼儿配方奶粉中4种多不饱和脂肪酸(二十二碳六烯酸、花生四烯酸、亚油酸和α-亚麻酸)含量的差异性。乙酰氯-甲醇甲酯化法和酸水解酯化法明显优于碱水解酯化法。乙酰氯-甲醇甲酯化法中,样品的水解和脂肪的甲酯化同时进行并相互促进,使得脂肪的释放和甲酯化能够完全进行。通过对反应过程和添加回收率两个方面的考察,证明了乙酰氯-甲醇甲酯化法检测结果的准确性。酸、碱水解酯化法是分别利用酸、碱对样品进行水解,然后提取脂肪进行甲酯化。从水解效率、提取效率及甲酯化效率3个方面对酸、碱水解酯化法进行对比,结果表明,水解效率是影响酸、碱水解差异性的主要因素,酸水解法更适用于婴幼儿配方奶粉中不饱和脂肪酸的测定。通过对实际样品的检测,进一步验证了乙酰氯-甲醇甲酯化法和酸水解酯化法测定多不饱和脂肪酸的准确性,同时对其他食品中脂肪酸的测定具有较强的指导意义。

Differences of three pretreatment methods for the detection of docosahexaenoic acid,eicosatetraenoic acid,linoleic acid and α-linolenic acid in infant formula milk powder

The differences of three pretreatment methods (acetyl chloro carbinol esterification, acid hydrolysis esterification and alkali hydrolysis esterification) for the detection of four polyunsaturated fatty acids (docosahexaenoic acid, arachidonic acid, linoleic acid and α -linolenic acid) in infant formula milk powder were discussed. Acetyl chloro carbinol esterification and acid hydrolysis esterification were found to be significantly better than alkali hydrolysis esterification. The sample digestion and fat methyl esterification were carried out simultaneously in the acetyl chloro carbinol esterification method, where the two processes seemed to enhance each other. This allowed the complete release and methyl esterification of the fats. The accuracy of the methods was determined by investigating the reaction processes and recovery rates. Acid and alkali hydrolysis esterification methods were employed to hydrolyze the samples using a hydrochloric acid solution and an ammonia solution, respectively. Then, the fats were extracted for subsequent methyl esterification. These two methods were compared in terms of the digestion efficiency, extraction efficiency, and methylation efficiency. The results showed that the digestion efficiency is the main factor determining the differences between the acid and alkali hydrolysis methods. The accuracies of acetyl chloro carbinol esterification and acid hydrolysis esterification methods were further verified in the detection of samples, providing a basis for the determination of fatty acids in other foods.