Process for the preparation of monosodium glutamate

Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof

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C07C22900

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active

059070595

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BRIEF SUMMARY
The present invention relates to a process for the preparation of monosodium glutamate (hereinafter referred to as MSG) from a glutamic acid fermentation broth.
More particularly, the present invention relates to a process for the preparation of MSG from a fermentatively-prepared solution containing monoammonium glutamate.
MSG is a well-known food additive which has been used for decades and which is used today mainly in the Far East, with a consumption of about 800,000 tons annually. Because of the great demand for MSG, many processes have been developed and/or proposed for the preparation thereof.
Thus, e.g., U.S. Pat. Nos. 2,877,160 and 2,978,384 teach various fermentation processes for the production of glutamic acid; U.S. Pat. Nos. 2,773,001 and 2,947,666 teach such processes in conjunction with the use of strong cation exchange resins to absorb glutamic acid, which is then eluted with normal hydrochloric acid or with dilute ammonium hydroxide, respectively.
In 1967, U.S. Pat. No. 3,325,539 was published, in which there was described and claimed a method for separating glutamic acid and salts thereof from a fermentation broth containing the same and solid materials, which method comprises passing fermentation broth containing glutamic acid, salts thereof, and solid materials upflow through a bed of strongly acidic cation exchange resin on the hydrogen cycle at a rate sufficient to expand the bed between 1.05 and 1.6 times its original depth, thereby adsorbing glutamic acid on said resin; discontinuing the flow of fermentation broth over said resin; and eluting said adsorbed glutamic acid from said resin with a 0.5-2 N sodium hydroxide solution.
MSG production via adsorbing glutamic acid on an acidic cation exchanger, as suggested in U.S. Pat. No. 3,325,539, suffers from several disadvantages: (1) a high consumption of reagents, entailing production of large amounts of by-product salts; (2) using an acidic cation exchanger frequently results in crystallization of glutamic acid on the resin material (column 3, lines 18-20); (3) the cation exchanger adsorbs the glutamic acid as well as the cation bound to it, and the cations present as impurities in the fermentation liquor, mostly resulting from the carbohydrate feed. As a result, large volumes of the resin are required. In many cases, only about one-third of the total available cation exchange capacity is available for glutamic acid adsorption.
The reactions involved with the process using acidic cation exchangers to adsorb glutamic acid (H.sub.2 G) from an acidic solution and regeneration by a base are as follows:


______________________________________ (1) NH.sub.3 + H.sub.2 G + NH.sub.4 HG Neutralization in fermentation (2) NH.sub.4 HG + 2R.sup.- H.sup.+ + R.sup.- NH.sub.4.sup.+ + R.sup.- H.sub.3 G.sup.+ (3) R.sup.- H.sub.3 G.sup.+ + 2NaOH + R.sup.- Na.sup.+ + NaHG + 2H.sub.2 O (4) R.sup.- Na.sup.+ + R.sup.- NH.sub.4.sup.+ + H.sub.2 SO.sub.4 + 2R.sup.- H.sup.+ + 1/2 Na.sub.2 SO.sub.4 + 1/2 (NH.sub.4).sub.2 SO.sub.4 (5) H.sub.2 G + 2NaOH + NH.sub.3 + H.sub.2 SO.sub.4 + NaHGA + 1/2 Na.sub.2 SO.sub.4 + 1/2 (NH.sub.4).sub.2 SO.sub.4 ______________________________________
Such a process doubles the consumption of extra base and acid values, and produces two equivalents of by-product salt per mole of the product. In fact, reagent consumption and by-product formation are even higher, as shown in U.S. Pat. No. 3,325,539. The MSG obtained in reaction (3) above is acidulated to pH=3.2 to crystallize the glutamic acid, which is then neutralized.
Five years later, in 1972, U.S. Pat. No. 3,655,746 was published, which describes the attempts to find a satisfactory process for producing MSG, as follows: MSG from a glutamic acid fermentation broth, but those processes invariably involve the steps of allowing glutamic acid hydrochloride, calcium glutamate, zinc glutamate, ammonium glutamate or glutamic acid to crystallize from the broth, then recovering those crystals and subsequently neutralizing them with, for instance, sodium hydroxide or sodium carb

REFERENCES:
patent: 2306646 (1942-12-01), Shildneck
patent: 2584731 (1952-02-01), Ogawa et al.
patent: 2905711 (1959-09-01), Novak et al.
patent: 3360555 (1967-12-01), Frump et al.
patent: 3655746 (1972-04-01), Shiraishi et al.
patent: 4956471 (1990-09-01), Ito et al.

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