微孔板法在测定乳粉中叶酸含量的应用研究  

Study on the Application of Microtiter Plate Microbiological Method in the Determination of Folic acid Content in Milk Powder

作　　者：蔡诗韵 陈梓红 李思颖 杨维奕 任郑骅 CAI Shiyun;CHEN Zihong;LI Siying;YANG Weiyi;REN Zhenghua(National Processed Food Quality Inspection and Testing Center(Guangdong),Guangzhou Inspection Testing and Certification Group Co.,Ltd.,Guangzhou Guangdong 511400)

机构地区：[1]广州检验检测认证集团有限公司,国家加工食品质量检验检测中心(广东),广东广州511400

出　　处：《中国乳业》2025年第2期91-99,共9页China Dairy

摘　　要：[目的]在GB 5009.211—2022基础上,对关键的试验条件包括:接种液制备方式、培养时间、前处理方式进行优化和细化,建立本实验室准确、稳定的用于测定乳粉中叶酸含量的微孔板法。[方法]分析不同接种液制备方式(离心-洗涤和消耗)、接种液浊度(0.5 MCF、1.0 MCF、1.5 MCF)、培养时间(22 h、32h、40 h)对鼠李糖乳杆菌生长标准曲线的影响,并结合标准参考物质(SRM 1869)叶酸含量的测定结果,得出最优条件。对SRM 1869、QC-IP-737和20种市售乳粉,分别使用氢氧化钠乙醇溶液超声和水浴进行处理,比较叶酸含量测定结果差异,并在95%置信水平下进行t检验,分析两种前处理方式的差异性。[结果]在相同浊度下,使用离心-洗涤的方式制备接种液优于消耗,且调节浊度为1.0,36℃培养40 h更佳。在95%置信水平下,SRM 1869、QC-IP-737和20种市售乳粉t检验结果P>0.05,说明两种前处理方式对测定结果的影响无显著差异。[结论]本研究优化了GB 5009.211—2022中接种液的制备方式,细化了培养时间和乳粉的前处理方式。其中建立的微孔板法可为后续国标的修订提供数据支持。优化后的试验条件可为其他实验室开展该项检测提供科学参考。[Objective]Based on GB 5009.211-2022,key experimental conditions including inoculum preparation method,culture time and pretreatment methods were optimized and refined to established an accurate and stable microtiter plate microbiological method for the determination of folic acid content in milk powder.[Method]The effects of different inoculum preparation methods(centrifugation-washing and consumption),McFarland turbidity of inoculum(0.5 MCF,1.0 MCF,1.5 MCF),culture time(22 h,32 h,40 h)on the growth standard curve of Lactobacillus rhamnosus were analyzed,and the folic acid content measured by the standard reference material(SRM 1869)was combined to optimize the test conditions.SRM 1869,QC-IP-737 and 20 commercial milk powder were treated with sodium hydroxide ethanol solution by ultrasound and water bath,respectively.The determination results of folic acid content were compared,and t-test was conducted at 95%confidence level to analyze the differences between the two pretreatment methods.[Result]The results showed that under the same McFarland turbidity,the inoculum prepared by centrifugation-washing was better than consumption,and adjusting the McFarland turbidity to 1.0 MCF and incubating at 36℃ for 40 h was recommended.At 95%confidence level,the P-values of the t-test results of SRM 1869,QC-IP-737 and 20 commercial milk powder were>0.05,indicating that the two pretreatment methods had no significant difference in the influence of the determination results.[Conclusion]This study optimized the preparation method of inoculum,refined the culture time and the pretreatment method of milk powder in GB 5009.211-2022.The established microtiter plate microbiological method could provide data support for the subsequent revision of national standards.The optimized experimental conditions could provide scientific reference for other laboratories to carry out this work.

关 键 词：叶酸 微孔板 微生物法 乳粉 前处理 

分 类 号：TS252.7[轻工技术与工程—农产品加工及贮藏工程]