1866, German chemist Karl Heinrich Leopold Ritterhausen hydrolyzed wheat bran with sulfuric acid to obtain acidic amino acids. 1908, Japanese scientist Dr. Ikeda Miaoju used kelp to separate delicious ingredients, and proved that this delicious ingredient was sodium glutamate, thus producing chemical seasonings and putting them on the market. Monosodium glutamate is a common condiment in life, and its main component is sodium glutamate. The flavoring effects of tomatoes, fermented bean products, yeast extracts, some pointed cheese and fermented or hydrolyzed protein products are partly attributed to.
Glutamic acid fermentation takes about 15% glucose as carbon source, adds appropriate amount of inorganic salt and biotin to prepare fermentation medium, and then cools it to 40℃ and sends it to an empty sterilization fermentor. Using liquid ammonia as nitrogen source, after two-stage expanded culture, glutamic acid-producing bacteria were inoculated. At present, freezing isoelectric point ion exchange method is generally used for extraction. The fermentation broth is slowly stirred and cooled to 5℃ with frozen brine in an equipotential tank, and the Ph value is adjusted to 3.22 with sulfuric acid; After 8 hours of precipitation, crude glutamic acid was obtained by centrifugal separation. Mixing mother liquor and supernatant, exchanging with ion exchange resin, and eluting with ammonia water; The former part flows into the supernatant and then returns to the column. The latter part is used as eluent together with ammonia water, and the higher part is returned to the equipotential tank together with fermentation broth. Adding glutamic acid into a neutralization tank with bottom water at 60-65℃, stirring, slowly adding soda solution to neutralize until the Ph value is 6.2-6.4, and controlling the concentration of neutralization solution to be relative density1.1.7-1.1.08; When that neutralize solution is cooled to below 50 DEG C, an appropriate amount of sodium sulfide solution is adde to remove iron; Then adjust the Ph value to 6.2 ~ 6.4 with crude glutamic acid, and raise the temperature to 60℃, then add powdered activated carbon, stir for half an hour, and then send it to a filter press for filter pressing; Step two, decolorizing the filtrate with granular activated carbon column to obtain clear liquid; The clear liquid is sent to a vacuum crystal boiling tank, evaporated and concentrated at 60 ~ 70℃ to a relative density of 65438 0.28, and after adding 0.3 6~0.542mm seed crystals, evaporation and crystallization are continued. It is necessary to add a certain amount of clear liquid and kill the crystals with hot water. After discharging, the crystal monosodium glutamate is obtained by centrifugal separation in a crystal growth tank, and the mother liquor is evaporated and crystallized after decoloration. The refining yield can reach 92% of the theoretical amount.