食品检测用单核细胞增生李斯特氏菌标准物质的研制

Preparation of Listeria monocytogenes reference material for food analysis

中文关键词:  单核细胞增生李斯特氏菌  标准物质  均匀性  稳定性

英文关键词:Listeria monocytogenes  reference material  homogeneity  stability

中文摘要:

      目的 建立食品检测用单核细胞增生李斯特氏菌标准物质的制备方法, 研制均匀稳定的标准物质。方法 利用冷冻干燥法制备103 CFU/样品的标准物质, 参照CNAS-GL 29《标准物质/标准样品定值的一般原则和统计方法》, 抽取20件样品, 利用平板计数法测定标准物质的均匀性, 并对结果进行统计分析; 将样品分别置于?20、25、37 ℃条件下保藏, 对其储藏稳定性和运输稳定性进行评价。组织5家实验室进行协同标定, 使用30种即食熟肉制品作为基质, 并按照国标法检验标物物质的适用性。结果 采用单因素方差分析进行均匀性检验, F=0.922, 符合标准物质的要求。标准物质在?20 ℃保藏28 d, 25、37 ℃保藏7 d, 样品仍然稳定。经5家实验室协同标定, 样品含量均在103 CFU/样品的水平; 标准物质加入到30种即食熟肉制品中, 均可以检出单核细胞增生李斯特氏菌。结论 本研究所制备的单核细胞增生李斯特氏菌标准物质的均匀性、储藏稳定性和运输稳定性均符合要求, 适用性良好, 可用于食品检测实验室的质量控制和食品中单核细胞增生李斯特氏菌检测结果的评价。

英文摘要:

      Objective To establish the method for preparing Listeria monocytogenes reference material for food analysis, and develop homogenous and stable reference material. Methods The standard substance of 103 CFU/ sample was prepared by freeze-drying method. According to CNAS-GL 29 General principles and statistical methods for the determination of standard substances/standard samples, 20 samples were selected, the homogeneity of standard substance was determined by plate counting method and the results were analyzed statistically. The samples were stored at ?20, 25, and 37 °C, respectively, and their storage stability and transport stability were evaluated, then 5 laboratories were organized for collaborative calibration, 30 ready-to-eat cooked meat products were used as the matrix, and the applicability of the target substance was tested according to the national standard method. Results The homogeneity was analyzed by one-way anova, F=0.922, which indicated the reference material prepared in the study could meet the requirement of homogeneity for reference material. The reference material remained stable after storage at ?20 ℃ for 28 d, 25 ℃ and 37 ℃ for 14 d. Additionally, the sample was confirmed at the level of 103 CFU/sample by the collaborative calibration with 5 laboratories. Added to 30 kinds of ready-to-eat meat products, the Listeria monocytogenes in the reference material remained detectable. Conclusion The homogeneity, storage stability and transportation stability of Listeria monocytogenes reference material prepared in this study all meet the requirements and have good applicability, which can be used for quality control of food testing laboratory and evaluation of detection results of Listeria monocytogenes in food.