食品安全国家标准中菌落总数测定方法影响因素分析

Influencing factors analysis of the aerobic plate count method in the national standard of food safety

中文关键词:  菌落总数  影响因素  PCR 培养基

英文关键词:total plate count  influencing factors  PCR medium

中文摘要:

      目的 对GB 4789.2-2016菌落总数测定方法的重要影响因素进行了系统分析。方法 使用大肠埃希氏菌ATCC25922、金黄色葡萄球菌ATCC6538和枯草芽孢杆菌ATCC6633的新鲜菌株和冻干样品评价PCA培养基的倾注温度(45 ℃和50 ℃)、已处理样品放置时间(0~90 min)、培养基倾注体积(12~20 mL)、培养基品牌(7种, 编号A-G)的差异对菌落总数计数结果的影响。结果 已处理样品放置90 min后, 菌落总数的计数结果显著性低于放置0 min(P=0.023)和15 min(P=0.021)样品的计数结果; 使用品牌B培养基得到的菌落计数结果显著性低于使用品牌F培养基得到的结果(P=0.024)。PCA培养基倾注温度(45 ℃和50 ℃)和倾注体积(12~ 20 mL)对菌落总数计数结果的影响未见显著性(P>0.05)。结论 需细化国标菌落总数测定方法检验流程, 研发并引入可靠的参比培养基, 对检验过程予以高度规范化, 以保障检验数据稳定、可靠。

英文摘要:

      Objective To analyze the important influencing factors of total bacterial count in GB 4789.2-2016 systematically. Methods The influence of the difference of pouring temperature (45 ℃ and 50 ℃), processed sample placement time(0-90 min), culture media infusion volume(12-20 mL) and medium brand (7 types, No.A-N) of PCA medium on the count results of total plate count were evaluated using the fresh strains and freeze-dried samples of Escherichia coli ATCC25922, Staphylococcus aureus ATCC6538 and Bacillus subtilis ATCC6633. Results After the treated samples were placed for 90 min, the count results of total colony count were significantly lower than those of 0 min (P=0.023) and 15 min(P=0.021). The results of colony count obtained by using brand B medium were significantly lower than those obtained by using brand F medium (P=0.024). The influence of PCA medium pouring temperature (45 ℃ and 50 ℃) and pour into volume (12-20 mL) for the result of the total number of bacterial colony count was not significant (P>0.05). Conclusion It is necessary to refine the inspection process of the national standard test method for total population of bacterial colonies, develop and introduce reliable reference medium, and highly standardize the inspection process to ensure the stability and reliability of test data.