GB738184A - Improvements in or relating to process for the production of monoclinic glutamic acid crystals - Google Patents

Abstract

An improvement or modification of the process for the production of monoclinic glutamic acid crystals of the parent Specification, is characterized by admixing with an aqueous solution containing between 4 per cent and 40 per cent glutamic acid hydrochloride with vigorous agitation sufficient sodium hydroxide or monosodium glutamate to adjust the pH of said mixture to between 2.5 and 4.0, said aqueous solution containing from the commencement of the pH adjustment up to about thirty seconds after the completion of said adjustment at least one monoclinic glutamic acid crystal nucleus, said adjustment being completed prior to the formation of any orthorhombic crystals, and recovering monoclinic glutamic acid crystals from the resultant crystal containing slurry. The monosodium glutamate and glutamic acid hydrochloride solutions employed may be prepared in any conventional manner from materials from which glutamic acid may be formed on hydrolysis such as animal and vegetable proteins and concentrated Steffen's filtrate and crude hydrolysate or prepared solutions may be employed in preparing the monoclinic glutamic acid. When seed crystals are employed they may be used in the form of a slurry or after separation from the mother liquor. In the original production of seed crystals sodium hydroxide or a solution containing monosodium glutamate is added to a solution containing between about 4 and about 20 per cent of glutamic acid hydrochloride. When solutions containing higher concentrations of glutamic acid hydrochloride are employed rapid stirring should be started as soon as crystallization of monoclinic crystals begins. The solutions may be mixed at atmospheric or higher temperatures. In a continuous process a slurry of monoclinic glutamic acid seed crystals in glutamic acid hydrochloride is prepared and rapidly agitated whilst glutamic acid hydrochloride solution and the solution which adjusts the pH of the mixture are added simultaneously and continuously. The mixture may take place in a small container and the slurry may be continuously removed to a larger container to crystallize the monoclinic glutamic acid. Batch processes may be operated. In examples: monoclinic glutamic acid is obtained when aqueous sodium hydroxide solution is added to aqueous glutamic acid hydrochloride solution to adjust the pH to between 3.0 and 3.3 within three to five seconds (1); aqueous monosodium glutamate solution is employed in a similar process instead of sodium hydroxide solution (2); monoclinic glutamic acid is obtained by adding concentrated sodium hydroxide solution to aqueous glutamic acid hydrochloride to which monoclinic glutamic acid seed crystals have been added. Specification 653,264 is referred to.