Industrial process for the preparation of amino acids by hydrolysis of proteins in acid medium

In a process for the industrial preparation of amino acids by hydrolysis of protein of animal or vegetable origin in a sulfuric acid medium within a reaction tank, comprising:

• conducting protein hydrolysis with sulfuric acid having a concentration of at least 12N and at a temperature of at least 100.degree. C., stopping the hydrolysis by addition of water so as to lower the temperature and to reduce the sulfuric acid concentration to a value of 6N or less and removing the excess of sulfuric acid by neutralization, the improvement wherein the reaction tank is charged with water and an initial portion of a sulfuric acid solution in an amount necessary for said hydrolysis of said protein, said tank is heated at a temperature between 100.degree. C. and the boiling point thereof prior to the addition of said protein to said tank, said water diluting the sulfuric acid solution initially added, so that the concentration of sulfuric acid within said reaction tank is about 12-14N, the protein to be hydrolyzed is then added simultaneously with but separately from a remaining portion of said sulfuric acid solution in an amount necessary for said hydrolysis in an amount corresponding to that required for the neutralization of amine groups of amino acids generated by the hydrolysis of the protein, so that said protein and said remaining portion of said sulfuric acid solution are added at independently adjustable rates while maintaining the concentration of acid with said reaction tank at about 12-14N.