Vitamin production process
1 Overview Vitamins are a kind of small-molecular organic compounds with different chemical structures and regulating the growth and development of organisms. They cannot be synthesized in human body and must be taken from food. The human body needs a small amount, but when it is insufficient, there is a corresponding deficiency. It is known that 13 kinds of vitamins are generally classified into water-soluble and fat-soluble vitamins according to solubility. There are three methods for the production of major vitamins.
In 2002, the output of vitamin raw materials in China reached 82,000 tons, of which vitamin C exceeded 50,000 tons, making it the world's largest producer and exporter of APIs. The annual output of vitamin preparations is 260-280 billion pieces/tablet/bottle, mainly based on tablets, injections and capsules.
2 Vitamin C production process Vitamin C (vitamin C) is currently the world's largest production and sales, the most widely used vitamin products. At present, the production of vitamin C in the world is about 100,000 tons/year, and the global market has sales of 500 million US dollars. At present, the industrial production of vitamin C uses a two-step fermentation method, which was researched by the Shanghai Institute of Biotechnology of the Chinese Academy of Sciences in 1975 and is the first in China. The production of vitamin C by fermentation can be divided into three major steps of fermentation, extraction and transformation. That is, the vitamin C precursor 2-keto-L-gulonic acid is extracted from D-sorbitol and then chemically converted to vitamin C.
The first step of fermentation: Acetobacter suboxydans is expanded by seed culture and connected to the fermenter. The seed and fermentation medium mainly include sorbitol, corn syrup, yeast extract, calcium carbonate and other components, pH 5.0~5.2. The alcohol concentration is controlled at 24~27%, and the culture temperature is 29~30 °C. After the fermentation is finished, the fermentation broth is sterilized by low temperature and transferred to the second step fermenter as raw material. The bioconversion rate of D-sorbitol to convert L-sorbose is over 98%.
The second step of fermentation: Gluconobacter oxydans (microbacterium) and Bacillus megaterium (Bacillus megaterium, large bacteria) mixed culture. Fermentation tanks for the production of vitamin C are all above 100 m3, slim and long, without mechanical agitation, with air-lifting. The composition of the seed and fermentation medium is similar, mainly L-sorbose, corn syrup, urea, calcium carbonate, potassium dihydrogen phosphate, etc., pH 7.0. Large and small bacteria are expanded and cultured by secondary seed, and connected to the fermenter containing the first fermentation broth. A large amount of sterile air is introduced at 29~30 °C, and the fermentation is finished for 72 hours. L-sorbose is formed 2- The conversion rate of keto-L-gulonic acid can reach 70-85%.
Separation and purification of 2-keto-L-gulonic acid: After two fermentations by two-step fermentation, the fermentation broth contains only about 8% of 2-keto-L-gulonic acid, and the residual mycelium, protein and Impurities such as suspended solid particles are usually separated and purified by a heating precipitation method, a chemical condensation method, or an ultrafiltration method. The traditional process is a heating precipitation method. After the fermentation liquid is settled by standing, it passes through a column of 732 hydrogen-type ion exchange resin, the pH is adjusted to the isoelectric point of the protein, and the protein is solidified by heating, and then the hyphae, protein and microparticles are separated by a high-speed centrifuge. The supernatant is again passed through a cation exchange column, acidified to an aqueous solution of 2-keto-L-gulonic acid, and concentrated to give 2-keto-L-gulonic acid.
Chemical conversion of 2-keto-L-gulonic acid: The conversion of the vitamin C precursor 2-keto-L-gulonic acid to vitamin C is often carried out by alkali conversion. 2-keto-L-gulonic acid is catalyzed by concentrated sulfuric acid in methanol to form methyl 2-keto-L-gulonic acid, converted with NaHCO3 to form vitamin C sodium salt, and acidified by hydrogen ion exchange resin to obtain vitamin C. . The crude product is refined by crystallization to obtain a finished vitamin C product.
3 Vitamin B2 production process Vitamin B2 (vitamin B2), also known as riboflavin, there are about 10 riboflavin producers in China. At present, the industrial production of vitamin B2 by microbial fermentation is widely used at home and abroad. The microorganisms capable of producing vitamin B2 are bacteria, fungi and molds, and industrial production mainly uses Eremotherecium ashbyii as a production strain. The industrial fermentation of vitamin B2 is generally a secondary fermentation, and the fermentation broth is first precipitated and reoxidized for separation and purification.
The fermentation medium contains vegetable oil, glucose, molasses or rice as the main carbon source. The vegetable oil has the most significant effect on the production of vitamin B2. The organic nitrogen source is mainly peptone, bone glue, fish meal and corn syrup. NaCl, K2HPO4, MgSO4. The aeration requirements for seed expansion culture and fermentation are relatively high. The ventilation ratio is generally 1.0, the tank pressure is about 0.05 MPa, and the stirring power requirement is relatively high. The optimum growth temperature of Pseudomonas aeruginosa is 28~30 °C, and the seed culture is connected to the fermenter after 34~38h. After fermentation for 40h, the continuous addition of sugar is started. The pH of the fermentation broth is controlled at 5.4~6.2, fermentation. The period is 150~160h. The yield of vitamin B2 is around 50 g/L.
Separation, extraction and purification of vitamin B2: The fermentation broth is heated by acidification, then added with yellow blood salt and zinc sulphate to precipitate protein. After filtration, the filtrate is adjusted to pH 1.5~2.0 for acidification, and allowed to stand for 20~40h precipitation. After filtration, the precipitate is acid-soluble. After adding ammonium nitrate, oxidizing and extracting, the oxidizing solution is crystallized and filtered, and the wet crystal is dried at 80 ° C or lower for 20 hours to obtain a finished vitamin B2.
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