测试片法检测食品中大肠菌群的验证评价

Validation of Coliform in Food by Test Tablets Method

为探究大肠菌群测试片法在食品检测中的可行性,依据国际标准ISO 16140-2:2016中的性能指标验证要求,对MicroFast^(®)大肠菌群测试片法进行包容性、排他性,以及与国家标准《食品安全国家标准食品微生物学检验大肠菌群计数》(GB 4789.3—2016)中方法的一致性验证,采用t-检验和Bland-Altman分析方法进行一致性分析评价。16株目标菌在测试片上形成典型菌落,24株非目标菌中的23株均未在测试片上形成菌落,阿巴特图巴沙门氏菌ATCC 35640在测试片上形成非典型菌落。测试片法和GB 4789.3—2016中方法的检测结果呈正相关(R^(2)>0.976);95%置信区间的样品比例为1∶25,满足不得高于1∶20的要求;所有食品类型的β-期望容忍区间(β-ETI)均在±0.5对数单位范围内,测试片法和GB 4789.3—2016方法具有很好的一致性。MicroFast^(®)大肠菌群测试片法对纯菌株的包容性和排他性良好,在一致性方面符合ISO 16140-2:2016对方法等效性的要求,可作为替代方法,用于检测食品中的大肠菌群。

This study was aimed to evaluate the feasibility of coliform detection in food by coliform test tablets.Based on performance indicator verification requirements of international standard ISO16140-2:2016,MicroFast^(®)coliform test tablets method was used for evaluation,including inclusivity,exclusivity,and consistency with GB 4789.3—2016 method,and t-test and Bland-Altman analysis were used for consistency analysis and evaluation.The 16 target strains all grew typical colonies on the test tablets,and 23 of the 24 non-target strains had no colonies on the test tablets.Salmonella Abatetuba ATCC 35640 formed atypical colonies on the test tablets.There was a positive correlation between the test tablets method and the national standard method(R^(2)>0.976).The proportion of samples exceeding the 95%confidence interval of the total average value of the difference was 1∶25,which met the ratio requirement of no more than 1∶20.The β-expected tolerance interval(β-ETI)for all food types was±0.5log10 units,the two methods were in good agreement.MicroFast^(®)coliform count plate had good performance in terms of inclusivity and exclusivity to pure strains,met the requirements of ISO16140-2:2016 for method equivalence in terms of consistency.It can be used as an alternative method for testing coliforms in food.