Process for the production of methionine

Provided is a process for producing methionine, which involves: (1) hydrolyzing 5-[2-(methylthio)ethylimidazolidine-2,4-dione in the presence of a basic potassium compound, (2) introducing carbon dioxide into a reaction liquid obtained in step (1), thereby precipitating methionine, and separating the resulting slurry into a precipitate and a mother liquid, (3) heat-treating the mother liquid obtained in step (2), and (4) introducing carbon dioxide into the mother liquid heat-treated in step (3), thereby precipitating methionine and potassium bicarbonate, and separating the resulting slurry into a precipitate and a mother liquid, wherein the alanine content in the mother liquid to be subjected to step (4) is 0.75 wt % or less.