Nitrogen and Protein Determination in Dairy Products (Kjeldahl Tablets)

Protein determination is one of the key analyses performed in the food industry. The samples require digestion with sulfuric acid to convert nitrogen into ammonium sulfate. Hydrogen peroxide is used to accelerate the digestion process. After conversion to ammonia through the alkalinization with sodium hydroxide, the sample is distilled into a boric acid receiver by steam distillation, followed by a titration with sulfuric acid solution. The nitrogen content is multiplied by a sample-specific protein factor (6.38 for dairy products) to obtain the protein content.