Methods of Manufacturing
The production method of choice for L-methionine is still the enzymatic resolution of racemic N-acetyl-methionine using acylase from Aspergillus oryzae. The production is carried out in a continuously operated fixed-bed or enzyme membrane reactor. Alternatively, L-methionine may be produced by microbial conversion of the corresponding 5-substituted hydantoin. With growing cells of Pseudomonas sp. strain NS671, D,L-5-(2-methylthioethyl)hydantoin was converted to L-methionine; a final concentration of 34 g/L and a molar yield of 93% have been obtained.
The most economic way for production of D,L-methionine is the chemical process based on acrolein, methyl mercaptan, hydrogen cyanide, and ammonium carbonate. beta-Methylthiopropionaldehyde, formed by addition of methyl mercaptan to acrolein, is the intermediate that reacts with hydrogen cyanide to give alpha-hydroxy-gamma-methylthiobutyronitrile. Treatment with ammonium carbonate leads to 5-(beta-methylthioethyl)hydantoin that is saponified by potassium carbonate giving D,L-methionine in up to 95% yield, calculated on acrolein. /D,L-Methionine/
U.S. Production
(1992) No data
World market for L-methionine in 1982: 150 tons; World market for DL-methionine in 1982: 110,000 tons
Production volumes for non-confidential chemicals reported under the Inventory Update Rule. Year Production Range (pounds) 1986 10 thousand - 500 thousand 1990 No Reports 1994 No Reports 1998 No Reports 2002 No Reports
Consumption Patterns
Used almost exclusively to improve the nutritive value of animal feeds /DL-Methionine/