Product monosodium Lglutamate

Figure 9. Recovery process flow of monosodium l-glutamate.

trolling the pH to neutrality with liquid ammonia. Molasses is fed until L-glutamic acid is no longer produced in the broth. The final L-glutamic acid concentration is around 95 g/L. Figure 8 shows a typical fermentation profile in a commercial plant. The method of penicillin addition provides remarkably high productivity of this amino acid compared with fermentation under suboptimal biotin conditions.

For purification of L-glutamic acid, two methods are available: the direct crystallization method and the chro-matographic ion exchange resin method. Because it is well known that the resin method can be used to purify all amino acids produced by fermentation, only the direct crystallization method is discussed here.

An outline of the recovery process (monosodium L-glutamate from L-glutamic acid fermentation broth) in a commercial plant is shown in Figure 9. The purification process may comprise an L-glutamic acid (GA) extraction process and an MSG process to obtain MSG from L-glutamic acid. In Figure 9 the GA extraction process discharges impurities out of the system as a GA mother liquor (containing microbial cells) to recover high-purity GA from the fermentation broth and an MSG mother liquor produced from the MSG process. High purity can be secured by efficiently washing crystals with water at a pH range near the isoelectric point. To this end, the crystal type (there are a- and ^-types) must be in the a-form, which can be easily separated by centrifugation.

In the MSG process it is essential to maintain the purity of the product while securing a high yield. These may be achieved by enhancing the purity of L-glutamic acid in the GA process and efficiently using the carbon source to achieve minimum levels of residues. Because the MSG mother liquor contains a high concentration of dissolved MSG, it is sent back into the GA process to augment the total yield of L-glutamic acid.

The GA mother liquor (containing spent cells) and a decolorized active carbon cake are the main fractions dis-

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  • Lidya
    What is msg motherliquor?
    8 years ago

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