Nitrogen and protein determination in rice
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. After conversion to ammonia through the alkalinization with sodium hydroxide, the sample is distilled into a sulfuric acid receiver by steam distillation, followed by a back titration with sodium hydroxide solution. The nitrogen content is multiplied by a sample-specific factor (6.25 for rice) to obtain the protein content.