Use and Manufacturing

3.1 DefinitionA white crystallinesolid compound, made fromsoya-bean protein. It is a sodium salt ofglutamic acid used as aflavor enhancer, particularly in Chinese cuisine. Monosodium glutamate can causean allergic reaction in people who are ultrasensitiveto it. Monosodium glutamate Preparation Products And Raw materials Raw materials

3.2 HistoryThe use of Monosodium glutamate(MSG) as a flavor enhancer is attributed to Kikunae Ikeda (1864 1936), a chemistry professor from Tokyo Imperial University. Ikeda patented Monosodium glutamate(MSG) as a flavor enhancer along with processes used to produce it. The isolated glutamic acid was then purified and converted to MSG. The use of Monosodium glutamate(MSG) as a flavor enhancer began in Japan and Asia, but widespread use of the compound in the United States did not occur until after World War II. Ajinomoto started manufacturing Monosodium glutamate(MSG) in the United States in 1956 (Ajinomoto became affiliated with Kraft General Foods in 1973).

3.3 Methods of ManufacturingAt present, both domestic and foreign countries use rice, starch or molasses as raw materials to produce through saccharification, fermentation, extraction and refining processes: (1) Saccharification of starch. The saccharification of starch mostly adopts the double enzyme method. Rice is soaked, sand-milled or starch is directly blended into starch slurry with relative density of 1.11 (14°Bé), and α-amylase is added to liquefy 15-20min under the condition of pH 4.5 and 90°C, and then heated to 100°C to kill enzyme 5min; After discharging, filter by plate and frame, the filter residue can be used as feed, the filtrate is adjusted to PH5.0, β-amylase is added, saccharification at 60℃ for 12h, and then heated to 100℃ to kill the enzyme and cool and clarify, the supernatant Put it directly into the sugar storage tank, add the filter aid diatomaceous earth to the sedimentation liquid and press filter, the starch sugar conversion rate can reach 92%. (2) Glutamate fermentation. Use about 15% glucose as the carbon source, and add appropriate amount of inorganic salt and biotin to prepare the fermentation medium. After continuous digestion and cooling to 40℃, it is sent to the sterilized empty fermentation tank, and the liquid ammonia is added. As a nitrogen source, it is inoculated with glutamic acid-producing bacteria that has undergone secondary expansion culture. After 30 hours of aeration fermentation, the sugar-acid conversion rate can reach 50% and the acid production level is about 7.0%-7.5%. The pH of the fermentation process is controlled at 7.0-7.2, and the temperature is controlled at 32-34°C in the early stage and 34-37°C in the later stage. (3) Extraction of glutamic acid. The extraction of glutamic acid generally uses the freezing isoelectric-ion exchange method. The fermentation broth was slowly stirred with frozen brine in an isoelectric tank to cool down to 5°C, while adjusting the pH to 3.22 (isoelectric point) with sulfuric acid; after 8h of precipitation, the precipitate was centrifuged to obtain crude glutamic acid; mother liquor and supernatant After liquid preparation, it is exchanged with ion exchange resin and dewashed with ammonia water; the front fraction is merged into the supernatant and re-loaded on the column, the latter fraction is used as the eluent together with the ammonia water, and the high fraction is returned to the isoelectric tank together with the fermentation broth for extraction The rate can reach 88%-90%. (4) Refining of glutamic acid. Add glutamic acid to a neutralization tank with 60-65℃ bottom water, stir, and slowly add soda ash solution to neutralize to pH 6.2-6.4, and control the concentration of the neutralization solution to a relative density of 1.17-1.18 (21- 22°Bé); After the neutralization solution is cooled to below 50°C, add an appropriate amount of sodium sulfide solution to remove iron, then use crude glutamic acid to adjust the pH to 6.2-6.4, and heat to 60°C, then add powdered activated carbon and stir After 0.5h, it is sent to a filter press and filtered, and then the filtrate is decolorized with a granular activated carbon column to obtain a clear liquid; the clear liquid is sent to a vacuum crystal boiling pot and evaporated and concentrated to a relative density of 1.28 (31.5°Bé) at 60-70°C After adding 0.36-0.542mm seed crystals, continue to evaporate and crystallize. During this period, hot water is required to kill the crystals and add a certain amount of clear liquid; after discharging, the crystal is incubated in a crystal tank and centrifuged to obtain crystalline monosodium glutamate. The mother liquor may be decolorized After evaporation and crystallization, the refining yield can reach 92% of the theoretical amount.