加压水解茚三酮光度法测定牛奶蛋白质

Determination of protein in milk by spectrophotometry after decomposition under pressurized condition

目的：建立牛奶蛋白质的光度测定方法。方法：将牛奶稀释液与1＋1硫酸混合置于电压力锅内,于115℃～116℃、0.17～0.18MPa条件下,水解1 h,水解产生的氨基酸用茚三酮显色,分光光度法测定。结果：牛奶稀释液中蛋白质含量在0.10～0.60 mg/ml之间,与吸光度成线性,相关系数r=0.9991,最低检出浓度0.02 mg/ml,方法回收率为91%～101.7%,相对标准偏差为0.84%～2.23%。

Objective：To establish a mathod for determination of protein in milk by spectrophotometry.Methods：After the milk was decomposed with H2SO4（1＋1） under pressurized condition（115℃~116℃,0.17~0.18Mpa,1 h）,the amino acids reacted with ninhydrin to form colored products and determined by spectrophotometry.Results：The linear range of the method was 0.10~0.60 mg/ml（r=0.9991）.The detection limit was 0.02 mg/ml with the recoveries of 91%~101.7% and its RSD was 0.84%~2.23%.