食品检测用鼠伤寒沙门氏菌标准物质的研制

Preparation of Salmonella typhimurium reference materials for food detection

中文关键词:  鼠伤寒沙门氏菌  标准物质  均匀性  稳定性

英文关键词:Salmonella typhimurium  reference materials  homogeneity  stability

中文摘要:

      目的 研制均匀稳定的鼠伤寒沙门氏菌标准物质。方法 采用冷冻干燥技术制备含量为1.5×103~2.0×103 CFU/样品的菌球, 参照CNAS—GL29:2010《标准物质/标准样品定值的一般原则和统计方法》, 随机抽取22件样品, 采用平板计数法进行均匀性检验, 采用单因素方差分析对结果进行统计分析, 将样品分别于?20、4、25、37 ℃条件下保藏, 对其储藏稳定性和运输稳定性进行评价, 并组织3家实验室进行协同标定。参照GB 4789.4—2016《食品安全国家标准 食品微生物学检验 沙门氏菌检验》方法, 再使用45件食品作为基质检验鼠伤寒沙门氏菌标准物质的适用性。结果 均匀性检测单因素方差分析结果F=1.986, P=0.059, 符合标准物质的要求。标准物质在?20 ℃保藏28 d, 复苏率为103.1%; 在4 ℃保藏28 d, 复苏率为102.0%; 在25 ℃保藏14 d或者37℃保藏7 d, 样品中菌含量仍保持在103 CFU/样品的水平, 说明样品的短期储藏稳定性、长期储藏稳定性和运输稳定性都符合要求。经3家实验室协同标定, 样品活菌含量均在103 CFU/样品水平, 生化鉴定结果均符合沙门氏菌的特征; 标准物质加入到45种食品基质中, 均可以检出沙门氏菌。结论 本研究所制备的鼠伤寒沙门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沙门氏菌检测结果的评价。

英文摘要:

      Objective To develop homogenous and stable reference materials of Salmonella typhimurium. Methods The reference materials with content of 1.5×103?2.0×103 CFU/sample were prepared by freeze-drying method, 22 samples were selected randomly, and the homogeneity of reference materials were determined by plate counting method and the results were analyzed statistically by one-way ANOVA according to CNAS—GL29:2010 Reference materials-General and statistical priciples for certification, the samples were stored at ?20, 4, 25 and 37 ℃ to evaluate the storage stability and transport stability, respectively, Then 3 laboratories were organized for collaborative calibration. Additionally, According to GB 4789.4—2016 National food safety standard-Food microbiological testing-Salmonella testing, 45 ready-to-eat food samples were selected as the matrices to test the applicability of the reference materials. Results The one-way analysis of variance result of homogeneity determination was F=1.986, P=0.059, which indicated that the reference materials prepared in the study could meet the homogeneity requirement for reference materials. The recoveries of reference materials reached 103.1% after storaged at ?20 ℃ for 28 d, and 102.0% after storaged at 4 ℃ for 28 d; and the content of Salmonella typhimurium remained the level of 103 CFU/sample after storage at 25℃ for 14 d or 37 ℃ for 7 d. Additionally, which indicated that short-term storage stability, long-term storage stability and transportation stability all met the requirements. The sample was confirmed as Salmonella and the content was at the level of 103 CFU/sample by the collaborative calibration with 3 laboratories. The Salmonella in the reference materials remained detectable when added to 45 ready-to-eat food samples. Conclusion The homogeneity, storage stability and transportation stability of Salmonella typhimurium reference materials prepared in this study meet the requirements for reference materials and has good applicability, which can be used for quality control of food testing laboratory and evaluation of detection results of Salmonella in food.