Production of methionine and its salt

PROBLEM TO BE SOLVED: To obtain methionine and its salt low in discoloration, excellent in storage stability with a by-product as small an amount as possible by a large- scale apparatus by a continuous operation. SOLUTION: 3-Methylmercaptopropionaldehyde, hydrogen cyanide, ammonia and carbon dioxide or components capable of producing these components are converted optionally in the presence of water into 5-(2-methylmercaptoethyl)- hydantoin and further converted into methionine or a methionine salt to give methionine as the objective compound. The conversion is preferably carried out at ≥80°C under ≥10bar. The conversion of the components is preferably performed through at least one premixture. COPYRIGHT: (C)1997,JPO