Determination of the protein content of wheat and barley by direct alkaline distillation

Abstract An improved alkaline distillation method is described for determining the protein content of wheat or barley. A complete estimation can be performed in about 15 minutes. The sample is distilled with a solution containing 10 % sodium hydroxide, barium chloride and antifoam and a specified volume of distillate collected and titrated with acid. Equations are given for calculating the protein content of the sample from the titration value. Different calibration equations are necessary for bread wheats, durum wheats and barley. Excellent agreement with the Kjeldahl method was obtained for analyses of the three grain types with correlation coefficients varying from 0.993 to 0.998 and standard errors ranging from 0.17 to 0.19% protein.