The pretreatment conditions for the determination of crude protein content in infant milk powder by automatic Kjeldahl nitrogen analyzer were optimized.The effects of sample size,catalyst ratio,concentration of sulfuric acid,digestion temperature and digestion time on the determination of crude protein content were investigated.The optimal pretreatment conditions were as follows:sample size 1.0 g,catalyst mass ratio 8∶0.5,concentration sulfuric acid addition amount 12.0 mL,digestion temperature and time:200 ℃(20 min),300 ℃(20 min),420 ℃(80 min).The standard deviation of parallel determination results was 0.54％,and the recovery rate was over 99％.The content of crude protein in milk powder was determined by optimized pre-treatment conditions with high precision and good stability.The results were close to the content marked on the outer package,which was in line with the national dairy protein content standard.
关键词
全自动凯氏定氮仪/婴幼儿奶粉/粗蛋白含量
Key words
automatic Kjeldahl nitrogen analyzer/infant milk/crude protein content
维普
万方数据