凯氏定氮法与杜马斯燃烧法检测三氯乙酸沉淀大豆和小麦蛋白中蛋白氮含量研究

Study on the detection of protein nitrogen content in soybean and wheat protein precipitated with trichloroacetic acid by Kjeldahl nitrogen determination method and Dumas combustion method

中文关键词:  大豆蛋白  小麦水溶性组分  蛋白氮与非蛋白氮  氮含量检测  三氯乙酸沉淀法

英文关键词:Soy protein  Water-soluble components of wheat  Protein nitrogen and non protein nitrogen  Nitrogen content detection  Trichloroacetic acid precipitation method

中文摘要:

      目的 检验尿素干扰下三氯乙酸沉淀分离大豆和小麦蛋白质的效果。方法 本研究以牛奶、大豆蛋白、小麦水溶性组分为参试样品，分别在去离子水、尿素溶液两种溶液体系下分散样品，参考国家标准采用三氯乙酸沉淀蛋白氮，2种蛋白检测方法(凯氏定氮法、杜马斯燃烧法)检测氮含量，并计算氮检测回收率评估三氯乙酸对大豆蛋白、小麦水溶性组分等植物性蛋白的适用性。结果 去离子水(无外源氮)分散的上清液经三氯乙酸沉淀，凯氏定氮法和杜马斯燃烧法检测牛奶的回收率分别为114%与101%，大豆的回收率分别为96%与98%，小麦的回收率分别为104%与105%。尿素溶液(有外源氮)分散的上清液经三氯乙酸沉淀，牛奶的回收率分别为99%和94%，大豆的回收率分别为95%和92%，小麦的回收率分别为101%和92%。结论 有无尿素干扰时，三氯乙酸均可以沉淀大豆蛋白、小麦水溶性组分中蛋白氮，并可以采用凯氏定氮法、杜马斯燃烧法检测，回收率较好。

英文摘要:

      To test the effects of trichloroacetic acid precipitation on the separation of soybean and wheat proteins under urea interference. Methods This study used water-soluble components such as milk, soy protein, and wheat as reference samples. The samples were dispersed in two solution systems: Deionized water and urea solution. According to national standards, trichloroacetic acid was used to precipitate protein nitrogen, and two protein detection methods (Kjeldahl nitrogen determination method and Dumas combustion method) were used to detect nitrogen content. The nitrogen detection recovery rate was calculated to evaluate the applicability of trichloroacetic acid to water-soluble components such as soy protein and wheat. Results The supernatant dispersed in deionized water (without external nitrogen) was precipitated with trichloroacetic acid. The recovery rates of milk using Kjeldahl nitrogen determination method and Dumas combustion method were 114% and 101%, respectively. The recovery rates of soybean were 96% and 98%, respectively. The recovery rates of wheat were 104% and 105%, respectively. The supernatant dispersed with urea solution (containing exogenous nitrogen) was precipitated with trichloroacetic acid. The recovery rates of milk were 99% and 94%, soybean was 95% and 92%, and wheat was 101% and 92%, respectively. Conclusion Trichloroacetic acid can precipitate protein nitrogen in soybean protein and wheat water-soluble components with or without urea interference, and can be detected by Kjeldahl method and Dumas combustion method, and the recovery rate is good.