微生物法测定婴幼儿乳粉中VB12的优化研究

Optimization of Microbiological Method Detecting VB12 in Infant Formula

为解决传统微生物法测定婴幼儿乳粉中VB12的含量试验过程操作繁琐、易受外部因素影响、方法重复性和准确度差等问题,该研究在GB 5413.14—2010的基础上,将菌株储备液分装于菌株保存管中,—70℃冻存备用,并确定该批次菌株试验中适宜菌浓度和培养时间。结合95℃水浴直接提取样品的优化方法进行准确度和重复性试验。结果表明,该批次菌株70%浓度、50μL接种量、培养20 h以上的试验方式,在VB12含量0.01~0.1 ng范围内,标准曲线线性关系优于国标方法,R2值可达到0.99以上;优化方法和国标方法所测结果都与标准样品的标示值相符,且相对于国标方法结果更准确,RSD为3.1%;重复性试验的RSD分别为3.1%、2.6%、3.2%、4.8%和3.2%。该方法操作简便、结果准确、重复性好,能克服传统微生物法的缺陷与不足,为VB12检测方法的改进提供参考。

In order to optimize the measurement of VB12 in infant formula by microbiological method,on the basis of national standard method GB 5413.14—2010,this study stored the reference stocks in the preservation tube,store at—70℃,determining the optimum bacterial concentration and incubation time in this batch of reference stocks.Combined with the optimization method of 95℃water bath direct extraction of samples to conduct accuracy and repeatability tests.The results showed that,in the test method with 70%concentration,50μL inoculation and more than 20 h of culture,during 0.01~0.1 ng,the linear relationship is better than the national standard method,the correlation coefficient was greater than 0.99.The results of both methods are consistent with the labeled values of the standard samples,and the results of the optimization method is more accurate,the RSD values was 3.1%.The RSD values of repeatability test were 3.1%,2.6%,3.2%,4.8%and 3.2%respectively.The new developed methods were proved to be simple,have good accuracy and repeatability,which could overcome the deficiencies of microbiological method to provide a reference for the improvement of VB12 detection method.