梨汁中外源性有机酸掺伪检测

Determination of Exogenous Organic Acids in Adulteration Pear Juice

柠檬酸和L-苹果酸是梨汁中2种主要有机酸。研究了利用高效液相色谱法分离测定梨汁中柠檬酸、L-苹果酸和D-苹果酸的条件,同时对来源于不同产地和品种梨汁中的柠檬酸和L-苹果酸的含量进行了测定。研究结果表明,不同品种梨汁中柠檬酸与L-苹果酸的含量和比例差别较大,同品种梨汁中这两种有机酸的比例差别不大。但是,在所有梨汁中柠檬酸的含量均小于苹果酸的含量,即,柠檬酸和L-苹果酸含量之比小于100%。因此,当梨汁中这两种有机酸的比例出现剧烈变化时,即可判定添加了外源有机酸。该方法解决了外源有机酸难以鉴别检测的难题,为生产企业及监管部门开展梨汁的掺伪鉴别提供了依据。

Citric acid and L-malic acid are 2 major organic acids in pear juices. A method for determining levels of citric acid, L-malic acid and D-malic acid in pear juices was developed, using reverse phase high performance liquid chromatography （HPLC）. The contents of citric acid and L-malie acid in pear juices from different cultivars and areas were determined. It is shown that there were notable differences in contents in pear juices from different cultivars; the same cultivars from different areas exhibited no notable differences. But in all pear juices, the contents of citric acid were less than that of L-malic acid, i.e. the ratio of citric acid to L-malic acid was less than one. Therefore, when there is dramatic variation in contents and ratio, exogenous organic acids must have been added into pear juices. This effective and feasible method will help detect adulteration pear juices.