| 摘要 |
PURPOSE:To obtain colorless methionine by treating an aqueous solution of a crude methionine salt, obtained by the hydantoin reaction or the Strecker reaction, in the presence of a specific reducing agent, without separating and the regenerating the decoloring agent. CONSTITUTION:An aqueous solution of methionine salt obtained by the hydantoin reaction or the Strecker reaction is neutralized with an acid, and purified by crystallization. Chemical decoloring of the methionine is carried out at an orbitrary stage after the formation of the methionine salt, by adding a small amount of a reducing agent comprising a salt of sulfurous acid, hydrosulfurous acid, disulfurous acid, thiosulfuric acid or thionous acid, or a sulfur dioxide gas. |
