微生物法检测叶酸、生物素、维生素B12接种液制备方法的优化

目的解决使用微生物法GB 5009.211-2014、GB 5009.259-2016、GB 5413.14-2010检测食品中叶酸、生物素、维生素B_(12)接种液制备耗时长的问题。方法将标准方法制备的接种液与甘油水按1:1(V:V)比例混匀,分装于小离心管,-80℃冻存。再通过用冻存不同时间的接种液检测样品,分析标准曲线线性、中间精密度和加标回收率来验证制备方法的适用性。结果标准曲线线性关系r~2均0.99,中间精密度叶酸RSD为1.5%～3.2%,生物素RSD为1.7%～4.2%,维生素B_(12) RSD为2.5%～9.3%;回收率方面,叶酸为99.5%～101.0%,生物素98.6%～101.3%,维生素B_(12)90.3%～96.4%。鼠李糖乳杆菌、植物乳杆菌、莱氏曼氏乳杆菌接种液超低温冻存有效时间长分别为6、8、3个月。结论优化后的接种液制备方法缩短了检测周期,操作简便、方法可靠,适合检测使用。

Optimization of preparation method of inoculating solution for microbial detection of folic acid, biotin and vitamin B12

Objective To solve the problem of time consuming in preparing the inoculum for the detection of folate, biotin and vitamin B12 in food by microbiological method GB 5009.211-2014, GB 5009.259-2016, GB 5413.14-2010. Methods Mix the inoculum prepared by the standard method with glycerin water in a ratio of 1:1(V:V), dispense into a small centrifuge tube, and freeze at ?80 °C. The applicability of the preparation method was verified by detecting samples with different time of cryopreservation, analyzing the linearity of the standard curve, the intermediate precision of the test results and the spike recovery rate of standard addition. Results Standard curve linear relationship r2>0.99. The intermediate precision of folic acid, biotin and vitamin B12 were 1.5%?3.2%, 1.7%?4.2%, 2.5%?9.3%, respectively. The recovery of folic acid was 99.5%?101.0%, biotin 98.6%?101.3%, vitamin B12 90.3%?96.4%. The effective time of cryopreservation of Lactobacillus rhamnosus, Lactobacillus plantarum and Lactobacillus lehmannii inoculums were 6, 8, 3 months, respectively. Conclusion The optimized preparation method of inoculum shortens detection period, is reliable and easy to operate, and is suitable for testing.