食品检测用木糖赖氨酸脱氧胆盐琼脂培养基标准物质的研制

Development of xylose lysine deoxycholine agar certified reference material for food detection

目的研制食品检测用木糖赖氨酸脱氧胆盐琼脂(xylose lysine deoxycholate agar,XLD)培养基标准物质。方法将XLD培养基各成分按比例称量、球磨后分装制成标准物质。倾注平板后观察培养基形态,检测pH。根据GB 4789.28—2013《食品安全国家标准食品微生物学检验培养基和试剂的质量要求》中选择性分离和计数固体培养基的测试项目,检验XLD培养基标准物质的均匀性。以40℃模拟极限运输条件检验XLD培养基标准物质的短期稳定性,以室温条件放置1、2、5、8、12个月的长期稳定性,并由3家实验室进行协作定值。结果制备的XLD培养基标准物质倾注平板后为红色半透明凝胶状固体,pH为7.45±0.02。均匀性和短期稳定性良好,长期稳定性在1年以上,协作定值结果符合GB 4789.28—2013的质控评定标准。结论本方法制备的XLD培养基标准物质均匀性与稳定性都达到标准物质的技术指标要求,可以用于食品中沙门氏菌检测的质量控制、实验室能力验证、实验室间比对等。

Objective To develop xylose lysine deoxycholate agar(XLD)medium certified reference material for food detection.Methods The components of XLD culture medium were weighed in proportion and packed into standard materials after ball milling.The morphology of culture medium and pH were observed after pouring plate.According to the test items of selective separation and counting solid medium in GB 4789.28—2013 National food safety standards-Food microbiological examination-Quality requirements for culture mediums and reagents,the homogeneity of XLD medium certified reference material was tested.The short-term stability of the XLD medium certified reference material was tested under the simulated limit transport condition at 40℃,and the long-term stability was tested under the condition of room temperature for 1,2,5,8 and 12 months,3 laboratories participated in the collaborative calibration.Results The prepared XLD medium certified reference material poured into the plate was a red translucent gelatinous solid with pH of 7.45±0.02.The homogeneity and short-term stability were good,and the long-term stability was more than 1 year.The results of collaborative calibration were in line with the quality control assessment standard of GB 4789.28—2013.Conclusion The homogeneity and stability of the XLD medium certified reference material can meet the technical requirements of the standard substance,and it can be used for the quality control,laboratory ability verification and laboratory comparison of Salmonella detection in food.