能力验证乳粉中乳酸菌计数不确定度的评定

目的对能力验证乳粉样品中乳酸菌计数进行不确定度评定。方法依据能力验证作业指导书和GB4789.35-2010《食品安全国家标准食品微生物学检验乳酸菌检验》进行测定,再根据JJF 1059.1-2012《测量不确定度评定与表示》对不确定度来源进行分析和评定。结果乳酸菌计数过程中,分散性对结果不确定贡献较大,因此测定结果的不确定度采用检测结果的分散性进行评定。6份样品乳酸菌计数结果扩展不确定度为分别为0.02012、0.04337、0.01992、0.03296、0.02182和0.031379(P=95%,k=2.09)。结论此方法适用于类似检测条件下乳酸菌计数不确定度的评定。

Uncertainty evaluation of lactic acid bacteria count in milk power by proficiency testing

Objective To evaluate the uncertainty of lactic acid bacteria count in milk power by proficiency testing. Methods Proficiency testing of lactic acid bacteria count was conducted under the direction of Reference book for microbiological ability verification plan in food and GB 4789.35-2010 National food safety standard Food microbiological examination: Lactic acid bacteria. Then, the uncertainty sources introduced in the experiment were determined according to JJF1059.1-2012 Evaluation and expression of uncertainty in measurements. Results The dispersion was the major contribution of the uncertainty in the detection of total bacterial colony, so the dispersion of results was evaluated for the uncertainty of determination results. The extended uncertainty results of 6 samples were 0.02012, 0.04337, 0.01992, 0.03296, 0.02182 and 0.031379 (P=95%, k=2.09), respectively. Conclusion The established method can be used in the uncertainty evaluation of lactic acid bacteria count under similar circumstances.