阪崎肠杆菌能力验证样品均匀性和稳定性的研究

The homogeneity and stability of samples used for E. sakazakii proficiency testing

目的制备出以脱脂奶粉为基质的均匀性好、稳定性强的阪崎肠杆菌(Enterobacter sakazakii)能力验证样品。方法研究奶粉基质的粒度、奶粉和菌粉的混合比例,得到阪崎肠杆菌能力验证样品的最佳均匀性条件;研究包装形式及贮存温度对样品稳定性的影响,得到阪崎肠杆菌能力验证样品的最佳稳定性条件。结果要保证样品足够均匀,奶粉最佳粒径范围为120μm<D<180μm,1 g菌粉最多与300 g奶粉进行混合;贮存温度对样品稳定性有较大影响,高温明显降低样品稳定性;真空包装可以显著提高样品稳定性。结论以奶粉为基质的阪崎肠杆菌能力验证样品的制备能够更准确地考查乳品微生物检验人员的检测水平,为国内微生物能力验证水平的提高奠定了基础。

Objective To prepare E.sakazakii proficiency testing samples with sufficient homogeneity and good stability,using skimmed milk powder as the matrix.Method The particle size of skimmed milk powder and the proportions of milk powder and E.sakazakii powder were studied to get the optimal conditions for the most homogeneous samples.The packaging forms and storage temperature were studied to get the optimal conditions for the most stable samples.Result The optimal conditions for the samples homogeneous enough were as follows： the partical size of skimmed milk powder is 120 μm D 180 μm.1 g of E.sakazakii powder should be mixed with no more than 300 g of milk powder.The storage temperature had significant influence on the stability of samples as high temperature would obviously decrease the stability of samples as high temperature would obviously decrease the stability of samples.Vacuum packing could improve the stability of samples,especially under high temperature.Conclusion The preparation of E.sakazakii proficiency testing samples,with skimmed milk powder as the matrix,can examine the detection level of dairy microbiological test more exactly,which lays a solid foundation for higher level of microbiology proficiency testing in China.