UPLC-MS/MS法快速测定乳酸菌发酵食品中的苯乳酸

Rapid determination of phenyllactic acid in lactic acid bacteria fermented food by UPLC-MS/MS

建立一种超高效液相色谱-串联质谱(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)快速测定发酵食品中苯乳酸的方法,并利用此方法对45种乳酸菌发酵食品中苯乳酸的含量进行测定。样品经甲醇提取,采用UPLC-MS/MS法,色谱柱为Shim-pack XR-ODS C_(18)(3.0 mm×75.0 mm,2.2μm),流动相为0.3%甲酸-水和0.3%甲酸-乙腈,梯度洗脱,流速为0.4 mL/min。苯乳酸在1~500 ng/mL范围内线性关系良好(R^(2)=0.9999),检出限和定量限分别为0.3和1 ng/mL,回收率为90.5%~105.0%,相对标准偏差为1.2%~4.4%。采用此方法对16种市售乳酸菌饮料、8种发酵乳、11种黄酒样品、发酵豆制品、米酒、奶酪、发酵香肠、馒头、面包等食品中苯乳酸的含量进行测定,结果显示所有样品中均含有苯乳酸。该研究所建立的方法前处理简单、分析时间短、灵敏度高、准确性好,适用于发酵食品中苯乳酸的测定。可以为高产苯乳酸菌株资源的挖掘以及发酵食品品质与营养功能的进一步研究提供科学依据。

Ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)was established to determine phenyllactic acid(PLA)in food fermented by lactic acid bacteria,and PLA was determined in 45 lactic acid bacteria fermented foods.Samples were determined by UPLC-MS/MS after pretreatment with methanol.PLA was separated on Shim-pack XR-ODS C_(18)(3.0 mm×75.0 mm,2.2μm)by gradient elution with 0.3%formic acid-acetonitrile and 0.3%formic acid-aqueous,and the flow rate was 0.4 mL/min.PLA showed a good linearity with the concentration ranged from 1 to 500 ng/mL(R^(2)=0.9999).The limits of detection and quantitation were 0.3 and 1 ng/mL,respectively.The recoveries ranged from 90.5%to 105.0%,and the relative standard deviations varied from 1.2%to 4.4%.The developed method was applied to the determination of PLA in fermented food including 16 lactic acid bacteria fermented beverages,8 fermented milks,11 Huangjiu,fermented bean products,rice wine,cheese,fermented sausage,steamed bread,bread,and other foods.The results showed that PLA was detected in all samples.The method established in this study is timesaving for sample pretreatment,high sensitivity and accuracy,and is suitable for the determination of PLA in fermented foods.This study provides scientific basis for the screening of PLA high-producing bacteria and further research on the quality and nutritional function of fermented food.