摘要
目的:建立二喹啉甲酸(BCA)测定牛奶中蛋白含量的方法。方法:用BCA法和凯氏定氮法分别测定食用牛奶蛋白含量;同时,添加尿素作为含氮干扰因素,测定其对BCA蛋白定量方法的影响。结果:BCA法蛋白定量精密度实验显示,平均吸光度为0.2798,标准偏差为0.004,加标回收实验的回收率为98.00%～103.00%。分别测定50倍、100倍牛奶稀释样品,结果50倍稀释样品组BCA法和凯氏定氮法测得蛋白质量浓度的平均值分别为791.2μg/mL和803.4μg/mL,100倍稀释样品组分别为370.2μg/mL和384.0μg/mL。添加尿素干扰实验显示,BCA法实验结果相对标准偏差在5%以下,而凯氏定氮法大于5%。结论:BCA法测定牛奶中蛋白含量结果可靠、稳定,与凯氏定氮法相比无显著差异;BCA法能排除含氮物质的干扰,该方法操作简便、结果准确可靠,可替代微量凯氏定氮法。
Bicinchoninic acid（BCA） method was used for determining protein content in milk and compared with Kjeldahl method.Meanwhile,the resistance of BCA method to interference of urea,a nitrogen-containing interferer,was analyzed.Results showed that an average absorbance at 562 nm wavelength was obtained in precision test of BCA method,and the standard deviation was 0.004.Spike recoveries at two levels of protein determined by BCA method were within the range of 98.00%-103.00%.In 6 replicated experiments,average values of protein content in 50-and 100-fold diluted milk were determined to be 791.2 and 803.4 μg/mL by BCA method and 370.2 and 384.0 μg/mL by Kjeldahl method,respectively.Experiments on urea interference revealed RSDs below and over 5% for protein determinations by BCA and Kjeldahl methods,respectively.As a conclusion,BCA method has the advantages of simplicity and good reliability,stability and resistance to urea interference,thereby providing an attractive alternative to Kjeldahl method for protein determination.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2010年第6期151-154,共4页
Food Science
基金
国家大学生创新性实验计划项目(071054251)
湖南省教育厅资助项目(08A036)
湖南省2008年大学生创新性实验项目(043-0094)
作者简介
吕媛（1965-），女，教授，博士研究生，研究方向为食品生物技术。E-mail：Ly598598@126．com。
通信作者：易银沙（1962-），男，副教授，研究方向为功能性食品。E-mail：Ly598598@yahoo．com．cn
