Proteins are polymers of amino acids linked to each other through peptide bonds and compounds of carbon, hydrogen, oxygen, nitrogen, and sulfur. They can be present in the membranes of the amyloplast, which stores starch. The basis of the process of determining proteins in food is the digestion of organic matter by heating with sulfuric acid until the nitrogen present in the sample is transformed into ammonium sulfate. Then, distillation is performed with concentrated sodium hydroxide and heating to release ammonia into a known volume of a boric acid solution, forming ammonium borate. The formed ammonium borate is titrated with a standardized acidic solution. Then the total nitrogen content is converted into the protein present in the sample.