微生物法测定婴幼儿配方乳粉中的泛酸含量
目的 采用微生物法测定5种市售婴幼儿配方乳粉中的泛酸含量, 探讨测定过程中的关键步骤、主要影响因素及容易出现的问题。方法 利用泛酸标准工作液制作泛酸标准曲线。将乳粉样品进行水解处理得到样品溶液。向试管中分别加入等体积的培养基及不同体积的样品溶液, 稀释至10 mL, 得到样品待测液。样品待测液和泛酸标准曲线溶液灭菌后, 加入植物乳杆菌(Lactobacillus plantarum, L. plantarum)ATCC 8014菌悬液进行培养, 将培养物混匀后测其吸光度值, 根据标准曲线计算出对应的泛酸含量, 并进行方法的重复性和加标回收率实验。结果 在0?50 ng/mL范围内, 泛酸标准曲线的线性关系良好, 相关系数r2为0.9982。标准对照品(standard reference material, SRM) 1849a中的泛酸含量为(6807?93) ?g/100 g, 与其标签标示值[(6820?190) ?g/100 g]相符; 泛酸加标实验回收率在94.20%?102.40%之间, RSD在1.82%?4.63%之间, 分析效果较好。结论 在对市售婴幼儿配方乳粉的检测中发现, 泛酸含量均符合要求, 但有的样品中泛酸含量高于标示值。
Objective To determine the content of pantothenic acid in 5 kinds of commercially available infant formula milk powders by microbiological method, and to discuss the key steps, main influencing factors and the problems easily appeared in the determination process. Methods Standard curve of pantothenic acid was prepared with working solution of pantothenic acid. Then the milk samples were hydrolyzed to sample solutions. The same volume of medium and different volume of sample solution were added to tubes, then diluted to 10 mL, and the samples to be checked were obtained. The samples to be checked and pantothenic acid standard solution were sterilized, then added with Lactobacillus plantarum (L. plantarum) ATCC 8014 bacterial suspension and cultivated. The absorbance of the mixture were measured and the corresponding pantothenic acid content was calculated according to the standard curve, the repeatabilities of the method and the standard recoveries were also tested. Results The standard curve reflected good linear relationship (r2=0.9982) in the range of 0~50 ng/mL, and the content of pantothenic acid in SRM 1849a was (6807?93) ?g/100 g, which was consistent with the label value [(6820?190) ?g/100 g]. The recoveries of pantothenic acid from samples ranged from 94.20% to 102.40%, the value of RSD ranged from 1.82% to 4.63%, and the analysis results were good. Conclusion Though the detection of commercially available infant formula milk powders, pantothenic acid content are in compliance with recommendations, and pantothenic acid content of some samples are higher than those declared on their nutritional labels.
标题：微生物法测定婴幼儿配方乳粉中的泛酸含量
英文标题：Detection of pantothenic acid in infant formula powders by microbiological method
作者：
李兴霖 黑龙江省质量监督检测研究院
杨光 黑龙江省质量监督检测研究院
赵平 黑龙江省质量监督检测研究院
丁松乔 黑龙江省质量监督检测研究院
中文关键词:微生物法,婴幼儿,配方乳粉,泛酸,测定,
英文关键词:microbiological method,infant,formula powders,pantothenic acid,determination,
发表日期：2017-04-12
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