Method of separation of glutamic acid of the residual liquid sugar juices after separation of the sugar

摘要

Glutamic acid is prepared by concentrating the pyrrolidone carboxylic acid-containing residual liquids which are obtained after the production of sugar from sugar-containing juices and from which the remaining sugar or a large proportion thereof has been removed, heating the concentrate with an alkaline earth metal oxide or hydroxide for approximately 10 to 15 minutes at a temperature of 80 DEG to 110 DEG C., cooling, diluting with one or more organic polar liquids or aqueous organic polar liquids, separating solids from the resulting liquid, removing the organic liquid by evaporation, concentrating the remaining liquid to a specific gravity of 1.2 to 1.4, hydrolysing this solution of pyrrolidone carboxylic acid with acid or alkali, and concentrating and adjusting the hydrolysate to approximately the isoelectric point of glutamic acid in order to precipitate said acid. Suitable starting materials are desugarized molasses, Steffen process waste waters and vinasse. Preferably 1 to 3 parts by weight of organic polar liquid are added to 1 part by weight of alkaline earth metal oxide or hydroxide-evaporated starting solution mixture. The evaporated starting solution preferably contains 2-15 per cent by weight of the alkaline earth metal oxide or hydroxide. Calcium oxide and hydroxide are specified for the latter purpose. Methanol and ethanol are specified as suitable organic polar liquids. The hydrolysis step is preferably effected with hydrochloric acid, as much as possible of the NaCl formed being removed.