Protein Nitrogen Determination

The protein content of foods can be determined by numerous methods. The Kjeldahl method and the nitrogen combustion (Dumas) method for protein analysis are based on nitrogen determination. Both methods are official for the purposes of nutrition labeling of foods. While the Kjeldahl method has been used widely for over a hundred years, the availability of automated instrumentation for the Dumas method in many cases is replacing use of the Kjeldahl method. This laboratory exercise includes determination of protein by both the Kjeldahl and Dumas methods.