Erythritol
Erythritol producing technology
1. Glucose syrup vacuum concentration:
The glucose syrup with a concentration of about 22% is vacuum-concentrated to remove some of the water, and the concentration of glucose syrup is raised to 50%, then fed into the fermentation system as a carbon source.
2. Triple expansion fermentation:
After the mature seeds were transferred to the fermenter, the bacteria were fermented and metabolized to produce erythritol fermentation broth under suitable conditions.
The air volume is 0.5 ~ 1.0VVM, the PH is 4.0 ~ 4.5, the temperature is 30 ~ 32℃, and the tank pressure is 0.03Mpa for about 120h.
3. Ceramic filter membrane:
The fermentation liquid was filtered by a 0.1-micron ceramic membrane to completely remove the insoluble suspended impurities and obtain a clean fermentation liquid with no solid content. The membrane interception solution was further filtered by diaphragm plate and frame to obtain the bacterial meringue cake.
4. Nanofiltration:
The clean fermentation liquid without solid content was separated by a nanofiltration membrane unit. Dissolved molecules with a molecular weight greater than 300 were basically removed, and the purity of about 96% of erythritol sodium filtrate was obtained.
5. Active carbon decoloration:
In order to adsorb organic impurities (including soluble colored impurities), the erythritol sodium filtrate was continuously decolorized by powdered activated carbon. Then the activated carbon and its adsorbed impurities were filtered by plate and frame filter press to obtain the refined erythritol solution.
6. Vacuum concentration:
The purified erythritol solution was removed by an MVR vacuum falling film evaporator, and the concentration increased from about 12% to 75% to obtain the refined erythritol slurry.
7. Evaporation crystallization:
The refined erythritol slurry was further removed by forced circulation vacuum evaporation crystallizer, and the concentration increased from about 75% to 80%. Due to the increase of supersaturation, erythritol crystals continuously precipitated and grew up, and a paste with a crystallization rate of about 60% was obtained.
8. Centrifugal separation:
The paste obtained by evaporation crystallization enters the horizontal cooling crystal aid machine, and the cooling speed is controlled automatically by adjusting the flow of cooling water. The drop in temperature causes the erythritol crystals to grow further until the temperature drops to 50℃. The paste with good crystal aid enters the upper hanging automatic scraper centrifuge, in which the erythritol crystal is retained in the sieve of the centrifuge, and then the automatic scraper is discharged, and the crystal is sent to the next process. Erythritol and impurities still dissolved in the solution, after being thrown out of the centrifuge, then is the mother liquid erythritol, part of it sent back, the remaining as a by-product to be sold.
9. Dissolve:
The erythritol crystals obtained after centrifugation are dissolved by heating water. High purity erythritol solution with a concentration of 50% at 60℃ was obtained.
10. Activate carbon secondary decolorization:
High purity erythritol solution was continuously decolorized by powdered activated carbon to adsorb organic impurities (including soluble colored impurities). Then the activated carbon and its adsorbed impurities were filtered by plate and frame filter press to obtain a high purity erythritol decolorization solution.
11. Ion Exchange:
After the removal of water-insoluble impurities and organic impurities in the solution, there are still some inorganic impurities soluble in water. These impurities exist in the form of cations and anions in the water. The purpose of ion exchange is to remove these water-soluble inorganic impurities and the cation in the solution exchange with H+ on the cation exchange resin. The anions in the solution exchange with OH- on the anion exchange resin, and finally exchange into the sugar solution H+ and OH- combine to form water, the inorganic impurities in the solution become the corresponding amount of water can be removed.
Of course, in order to maintain the exchange capacity of ion exchange resin, it is necessary to use acid and base to regenerate cation exchange resin and anion exchange resin respectively when their exchange capacity decreases.
12. Secondary vacuum concentration:
Part of the water of the purified erythritol solution was removed by an MVR vacuum falling film evaporator, and the concentration increased from about 48% to 75% to obtain the highly purified erythritol slurry.
13. Vacuum evaporation recrystallization:
The high purity refined erythritol slurry was further removed by forced circulation vacuum evaporation crystallizer, and the concentration increased from about 75% to 80%. Due to the increase of supersaturation, erythritol crystals continuously precipitated and grew, and a high purity paste with a crystallization rate of about 65% was obtained.
14. Secondary centrifugal separation:
The high purity paste obtained by secondary evaporation crystallization enters into a horizontal cooling crystallizer, and the cooling speed is controlled by automatically adjusting the flow of cooling water. The drop in temperature causes the erythritol crystals to grow further until the temperature drops to 50℃. The paste with crystal erythritol enters the upper hanging automatic scraper centrifuge, in which the erythritol crystal is retained in the sieve of the centrifuge, and then the automatic scraper is discharged, and the crystal is sent to dry. Erythritol and impurities still dissolved in the solution, after being thrown out of the centrifuge, then is the mother liquid erythritol, part of it sent back to secondary decolorization, part of it sent back to the first decolorization.
15. Drying:
After centrifugation, the erythritol crystal still contains about 1% moisture. In order to make the product to meet the quality standards and be able to be stored for a long time, it is necessary to reduce its moisture to less than 0.08% by drying. This project adopts counter-current fluid bed drying and cooling unit to complete the drying of erythritol.
16. Packing:
According to the market needs, the finished crystalline erythritol will be packed in different specifications and types to facilitate transportation to users.
