醋和蛋白饮料中脱氢乙酸两种前处理方法的比较研究

Comparative study on two pretreatment methods of dehydroacetic acid in vinegar and protein drinks

采用气相色谱法对醋和蛋白饮料中脱氢乙酸的含量进行测定,考察两种前处理方法对陈醋、红曲醋、2种白醋和4种蛋白饮料加标回收率的影响。方法一采用直接酸化后用乙酸乙酯提取,脱氢乙酸平均回收率为115.8%~126.2%,相对标准偏差(RSD,n=3)为0.34%~1.44%;方法二是经过硫酸锌和氢氧化钠调pH,使脱氢乙酸转化成钠盐溶于水,同时沉淀蛋白和杂质,脱脂后再酸化提取,其平均回收率为99.4%~106.2%,相对标准偏差(RSD,n=3)为0.31%~1.29%。结果表明,方法一中样品直接酸化提取,其回收率均偏高,方法二的样品前处理步骤更适用于醋和蛋白饮料中脱氢乙酸的测定,其结果更准确。

The content of dehydroacetic acid in vinegar and protein beverages was determined by gas chromatography,and the effects of two pretreatment methods on the recovery of mature vinegar,red yeast rice vinegar,two kinds of white vinegar and four kinds of protein beverages were investigated.Method one adopts direct acidification and then extracts with ethyl acetate,the average recovery rate of dehydroacetic acid was 115.8%~126.2%,and the relative standard deviation(RSD,n=3)was 0.34%~1.44%;in method 2,the pH was adjusted by zinc sulfate and sodium hydroxide,so that dehydroacetic acid was converted into sodium salt solution and dissolved in water,at the same time,the protein and impurities were precipitated,and then acidified and extracted after degreasing.The average recovery rate was 99.4%to 106.2%,and the relative standard deviation(RSD,n=3)was 0.31%to 1.29%.The results showed that the recovery rate of the samples was high in the method one,and the sample pretreatment steps in the method two were more suitable for the determination of dehydroacetic acid in vinegar and protein drinks,and the results were more accurate.