In the Kjeldahl procedure, proteins and other organic food components in a sample are digested with sul- furic acid in the presence of catalysts. The total organic nitrogen is converted to ammonium sulfate.The digest is neutralized with alkali and distilled into a boric acid solution. The borate anions formed are titrated with standardized acid, which is converted to nitrogen in the sample. The result of the analy- sis represents the crude protein content of the food since nitrogen also comes from nonprotein compo- nents (note that the Kjeldahl method also measures nitrogen in any ammonia and ammonium sulfate).