Claims
- 1. A method for preparing rhamnose from rhamnolipids comprising the steps of:
- a) hydrolyzing an aqueous acidic rhamnolipid emulsion having a pH value of 0 to 3.0 at a temperature of 110.degree. to 200.degree. C. for a period of 5 to 300 minutes to obtain a hydrolysate comprising a lipid phase and an aqueous phase,
- b) cooling said hydrolysate to a temperature below 100.degree. C. and separating said lipid phase from said aqueous phase,
- c) adding a basic compound to said aqueous phase to raise the pH to a value of 2.0 to 8.0, thereby precipitating the acidic ions as salts of low solubility,
- d) separating said precipitate from said aqueous phase, and
- e) concentrating the resulting rhamnose containing solution.
- 2. The method of claim 1, wherein water is the only solvent used in said method.
- 3. The method of claim 1, wherein said rhamnolipids are obtained by fermentation.
- 4. The method of claim 1, wherein said method is a continuous process.
- 5. The method of claim 4, wherein said lipid phase is brought back into said method no later than the hydrolysis step.
- 6. The method of claim 1, wherein said rhamnolipid emulsion has a conductivity of less than 12 mS/cm.
- 7. The method of claim 6, wherein said rhamnolipid emulsion has a conductivity of less than 5 mS/cm.
- 8. The method of claim 1, wherein said emulsion has a total solids content of 5 to 50% by weight.
- 9. The method of claim 8, wherein said emulsion has a total solids content of 10 to 20% by weight.
- 10. The method of claim 1, wherein said aqueous acidic rhamnolipid emulsion has a pH of 0.5 to 1.5.
- 11. The method of claim 1, wherein said hydrolysis is carried out at 110.degree. to 160.degree. C.
- 12. The method of claim 11, wherein said hydrolysis is carried out at 120.degree. to 150.degree. C.
- 13. The method of claim 1, wherein said aqueous phase of said resulting hydrolysate is separated from the lipid phase at a temperature of 50.degree. to 90.degree. C.
- 14. The method of claim 1, wherein the pH of the aqueous phase of step c) is raised to a value of 3.0 to 7.0 by the addition of a basic compound which forms a salt of low solubility with the acid anion contained in the resulting solution.
- 15. The method of claim 14, wherein said basic compound is Ca(OH).sub.2 and/or CaCO.sub.3.
- 16. The method of claim 1, wherein the aqueous phase which remains after said precipitate is removed in step d) is treated with a decolorizing agent.
- 17. The method of claim 16, wherein said decolorizing agent is selected from the group consisting of bentonite and activated carbon.
- 18. The method of claim 1, wherein the rhamnose containing solution is further purified by chromatography on an ion exchange resin.
- 19. The method of claim 18, wherein the rhamnose containing solution, following ion exchange chromatography, is concentrated to a total solids content of 20 to 60% by weight.
- 20. The method of claim 19 wherein the rhamnose containing solution is concentrated to a total solids content of 25 to 50% by weight.
- 21. The process of claim 1, further comprising crystallizing rhamnose monohydrate.
- 22. The method of claim 21, wherein the crystallization is carried out as a cooling crystallization or an evaporation crystallization.
- 23. The method of claim 22, wherein the crystallization is a cooling crystallization and the cooling is carried out at a cooling rate of 1.degree. to 10.degree. /hour.
- 24. The method of claim 23, wherein the cooling is carried out at a cooling rate of 3.degree. to 6.degree. /hour.
- 25. The method of claim 22, wherein the crystallization is an evaporation crystallization and wherein a supersaturation of 1.05 to 1.3 is maintained in the rhamnose containing solution from which rhamnose monohydrate is crystallized.
- 26. The method of claim 25, wherein a supersaturation of 1.1 to 1.15 is maintained in the rhamnose containing solution from which rhamnose monohydrate is crystallized.
Priority Claims (1)
Number |
Date |
Country |
Kind |
40 30 262.8 |
Sep 1990 |
DEX |
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Parent Case Info
This application is a continuation of application Ser. No. 07/977,401, filed as PCT/EP91/01426, Jul. 30, 1991, published as WO92/05182, Apr. 2, 1992, now abandoned.
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Continuations (1)
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Number |
Date |
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Parent |
977401 |
Mar 1993 |
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