甲醛值滴定法快速测定牛奶中蛋白质含量_田志梅.PDF

) 244 ) 2008 20 3 CHINESE JOURNAL OF FOOD HYGIENE 实验技术与方法 田志梅 ( 河北省衡水市疾病预防控制中心, 河北 衡水 053000) : 建立牛奶中蛋白质的快速检验方法- 甲醛值滴定法 利用氨基酸的两性特性, 入甲醛溶 液并用标准碱溶液滴定, 通过测定牛奶中蛋白质的游离氨基酸含量, 计算求得牛奶中蛋白质含量 牛奶中 蛋白质含量与游离氨基酸含量呈良好的正相关, RSD % 21 63~ 3140, 本法与国标法两种方法测定结果的绝对差值 与其算术平均值之比小于5% , 测定时间由约3 h 缩短为3~ 5 min 本方法有效地解决了非蛋白质类的含氮 物质对牛奶中蛋白质测定结果的干扰问题, 适用于牛奶与奶粉中蛋白质的快速定量检验 : 乳; 蛋白质类; 甲醛; 滴定分析法 Determination of Protein Contentin Milk by Formaldehyde Value Titration TIAN Zh-i mei ( Hengshui Municip l Center for Dise se Control nd Prevention, Hebei Hengshui 053000, Chin ) Abstract: Objective To determine protein content in milk by form ldehyde v lue titr tion. Method Using mphoteric property of mino cids, the form ldehyde solution w s dded into milk s mple, nd then the s mple w s titr ted by st nd rd lk li. The protein content in milk w s c lcul ted by determining free mino cids of it. Results There w s good correl tion between protein content in milk nd free mino cids. The RSD w s 21 63% ~ 3140% . Comp red with the n tion l st nd rd method, the r tios of bsolute difference to its rithmetic ver ge of two methods were ll below 5% . The determining time w s 3 ~ 5 min, nd less th n 3 h of n tion l st nd rd method. Conclusion The method could effectively resolve the interference problems of nitrogen subst nces which belong to non-protein kinds, nd pply to r pid qu ntit tive test of protein in milk nd milk powder. Key ord: Milk; Proteins; Form ldehyde; Titrimetry , 1 , 111 [1]