Determination of Protein in Liquid Emulsion by Graphite Digestion-Kjeldahl Nitrogen Analyzer and Verification of the Method
A method for determining protein content in liquid milk was established by using a graphite digestion instrument for digestion and a fully automatic Kjeldahl nitrogen analyzer for distillation and titration.The results showed that during distillation,the sample volume was taken as 1.0～2.5 g,sulfuric acid was taken as 5 mL,copper sulfate and potassium sulfate were used as 0.1 g and 1.5 g,respectively.During digestion titration,25 mL of alkali was added,10 mL of boric acid was added,20 mL of diluted water was added,and distillation time was 5 minutes.Under these conditions,the best effect was achieved.Ten representative liquid emulsions were selected for the validation of this method,and the results obtained all met the requirements of national standards.Compared with the traditional Kjeldahl method,this method is simple,safe,and efficient,and is suitable for daily detection of liquid milk proteins.
NETL
NSTL
万方数据
维普
