纯牛奶中蛋白氮测定与外源非蛋白氮风险监测  

Determination of Protein Nitrogen and Risk Monitoring of Exogenous Non-protein Nitrogen in Pure Milk

作　　者：徐纬[1] 聂四平[1] 李军 胡勇[1] 

机构地区：[1]贵州医科大学公共卫生学院环境污染与疾病监控省部共建教育部重点实验室,贵州贵阳550004

出　　处：《贵阳医学院学报》2015年第12期1334-1337,共4页Journal of Guiyang Medical College

基　　金：贵州省卫生厅科学技术基金项目(gzwkj2012-1-116)

摘　　要：目的:建立纯牛奶中蛋白氮测定与外源非蛋白氮风险监测方法。方法:纯牛奶经甲醛和三氯乙酸溶液沉淀分离蛋白质后,用自动凯氏定氮仪分别测定沉淀和滤液中氮含量,根据3倍标准偏差原则抽检确定纯牛奶中内源非蛋白氮标准范围,后监测纯牛奶中非蛋白氮与该范围的差异。结果:本文方法蛋白氮和非蛋白氮加标回收率分别为97.2%和101.7%(n=6),相对标准偏差RSD均小于5%,与国家标准方法比较,经配对t检验分析,纯牛奶中总氮的测定结果无显著性差异(P>0.05);样本中内源非蛋白氮服从正态分布(n=54),x±3 s=(0.306±0.120)g/L,能监测0.28 g/L外源非蛋白氮风险。结论:本文方法能有效排除外源非蛋白氮对蛋白氮测定的干扰,并可同时监测外源非蛋白氮风险,可用于纯牛奶中蛋白氮测定与外源非蛋白氮风险监测。Objective： To establish a method for the determination of protein nitrogen and monitoring risk of exogenous non-protein nitrogen in pure milk. Methods： After the proteins in pure milk were precipitated and separated by formaldehyde and trichloroacetic acid solution,nitrogen in the filtrate and precipitate were respectively measured by Automatic Kjeldahl nitrogen analyzer. According to the principle of three times sigma,the standard range of endogenous non-protein nitrogen in pure milk were determined by sampling,then monitored differences between non-protein nitrogen in pure milk and the standard range. Results： The recovery rate of this method for protein nitrogen and non-protein nitrogen were 97. 2% and 101. 7%（ n = 6）,the RSD were less than 5 %. The data was analyzed using paired t-test and showed that no significant difference between total nitrogen in pure milk determined by this method and the GB method（ P〉0. 05）. Endogenous non-protein nitrogen in pure milk obey normal distribution（ n = 54）,x ± 3 s =（ 0. 306 ± 0. 120） g / L. This method can monitor 0. 28 g / L of exogenous non-protein nitrogen. Conclusion： This method can effectively eliminate the interference of exogenous non-protein nitrogen on the determination of protein nitrogen,and can simultaneously monitor the risk of exogenous non-protein nitrogen,which can be used for the determination of protein nitrogen and the risk monitoring of exogenous non protein nitrogen in pure milk.

关 键 词：食品检查 蛋白质 非蛋白氮 

分 类 号：R151.3[医药卫生—营养与食品卫生学]