食品中金黄色葡萄球菌定量检测的不确定度评定

为提高食品中金黄色葡萄球菌定量检测结果的准确性,本文对测量不确定度进行分析和评定.按照《食品安全国家标准食品微生物学检验金黄色葡萄球菌检验》(GB 4789.10—2016)第二法金黄色葡萄球菌平板计数法对人工染菌的乳粉样品进行检测,按照《测量不确定度评定与表示》(JJF 1059.1—2012)分析不确定度来源、评定标准不确定度、计算合成标准不确定度和扩展不确定度.金黄色葡萄球菌定量检测结果的扩展不确定度U=0.0662(k=2.26),金黄色葡萄球菌定量检测结果为33574～45541 CFU·g-1,修约后为34000～46000 CFU·g-1.对金黄色葡萄球菌检测不确定度贡献最大的是接种Baird-Parker平板引入的不确定度,其次是重复检测引入的不确定度.

Evaluation of Uncertainty in Quantitative Detection of Staphylococcus aureus in Food

In order to improve the accuracy of the quantitative detection results of Staphylococcus aureus in food,the uncertainty in measurement was analyzed and evaluated.The artificially infected milk powder samples were tested according to the second method as plate counting method in GB 4789.10—2016.According to(JJF 1059.1—2012)to analyze the source of uncertainty,evaluate the standard uncertainty,and calculate the combined standard uncertainty and the expanded uncertainty.The expanded uncertainty of quantitative detection results of Staphylococcus aureus was U=0.0662(k=2.26).The result could be expressed as 33574~45541 CFU·g^-1 and 34000~46000 CFU·g^-1 after rounding.The most significant contribution to the uncertainty of the detection of Staphylococcus aureus is the uncertainty introduced by Baird-Parker plate inoculation,followed by the uncertainty introduced by repeated measurement.