REMOVAL OF FREE FATTY ACIDS FROM GLYCERIDE OILS

Abstract

The present invention relates to deacidification of glyceride oils. The present invention provides a process for removing free fatty acids from glyceride oil, preferably palm oil, containing free fatty acids, said process comprising the steps of: (i) contacting the glyceride oil containing free fatty acids with the basic ionic liquid; wherein the basic ionic liquid has a basic anion selected from hydroxide, alkoxide, alkylcarbonate, hydrogen carbonate, serinate, prolinate, histidinate, threoninate, valinate, asparaginate, taurinate and lysinate; and a cation selected from: [N(R.sup.a)(R.sup.b)(R.sup.c)(R.sup.d)].sup.+, wherein: R.sup.a, R.sup.b, R.sup.c and R.sup.d are each independently selected from hydrogen, a C.sub.1 to C.sub.8, straight chain or branched alkyl group or a C.sub.3 to C.sub.6 cycloalkyl group, wherein said alkyl or cycloalkyl groups are unsubstituted or may be substituted by one to three groups selected from: C.sub.1 to C.sub.4 alkoxy, C.sub.2 to C.sub.8 alkoxyalkoxy, C.sub.3 to C.sub.6 cycloalkyl, OH, SH, CO.sub.2(C.sub.1 to C.sub.6)alkyl, OC(O)(C.sub.1 to C.sub.6)alkyl, or any two of R.sup.a, R.sup.b, R.sup.c and R.sup.d combine to form an alkylene chain (CH.sub.2).sub.q wherein q is from 3 to 6; and (ii) obtaining a treated glyceride oil having a reduced content of free fatty acid compared to the glyceride oil feed of step (i).

Claims

1. A process for removing free fatty acids from glyceride oil containing free fatty acids comprising the steps of: (i) contacting the glyceride oil containing free fatty acids with a basic ionic liquid; wherein the basic ionic liquid has a basic anion selected from hydroxide, alkoxide, alkylcarbonate, hydrogen carbonate, serinate, prolinate, histidinate, threoninate, valinate, asparaginate, taurinate and lysinate; and a cation selected from:
[N(R.sup.a)(R.sup.b)(R.sup.c)(R.sup.d)].sup.+, wherein: R.sup.a, R.sup.b, R.sup.c and R.sup.d are each independently selected from hydrogen, a C.sub.1 to C.sub.8, straight chain or branched alkyl group or a C.sub.3 to C.sub.6 cycloalkyl group, wherein said alkyl or cycloalkyl groups are unsubstituted or may be substituted by one to three groups selected from: C.sub.1 to C.sub.4 alkoxy, C.sub.2 to C.sub.8 alkoxyalkoxy, C.sub.3 to C.sub.6 cycloalkyl, OH, SH, CO.sub.2(C.sub.1 to C.sub.6)alkyl, and OC(O)(C.sub.1 to C.sub.6)alkyl, or any two of R.sup.a, R.sup.b, R.sup.c and R.sup.d combine to form an alkylene chain (CH.sub.2).sub.q wherein q is from 3 to 6; and (ii) obtaining a treated glyceride oil having a reduced content of free fatty acid compared to the glyceride oil feed of step (i).

2. A process according to claim 1, further comprising separating one or more neutralisation salts of free fatty acids formed in step (i) and/or any residual basic ionic liquid from the treated glyceride oil.

3. A process according to claim 1 or claim 2, wherein the basic anion is selected from alkylcarbonate, hydrogen carbonate, hydroxide and alkoxide.

4. A process according to any of claims 1 to 3, wherein the basic anion is alkylcarbonate.

5. A process according to any of claims 1 to 3, wherein the basic anion is hydrogen carbonate.

6. A process according to any of claims 1 to 3, wherein the basic anion is hydroxide.

7. A process according to any of claims 1 to 3, wherein the basic anion is alkoxide.

8. A process according to any of claim 1 or claim 2, wherein the basic anion is selected from serinate, prolinate, histidinate, threoninate, valinate, asparaginate, taurinate and lysinate.

9. A process according to claim 8, wherein the basic anion is selected from the basic anion is selected from serinate, lysinate, prolinate, taurinate and threoninate.

10. A process according to claim 9, wherein the basic anion is selected from lysinate, prolinate and serinate.

11. A process according to claim 10, wherein the basic anion is lysinate.

12. A process according to any of claims 1 to 11, wherein the cation is selected from:
[N(R.sup.a)(R.sup.b)(R.sup.c)(R.sup.d)].sup.+, wherein: R.sup.a, R.sup.b, R.sup.c and R.sup.d are each independently selected from C.sub.1 to C.sub.8 alkyl, including C.sub.1, C.sub.2, C.sub.4 and C.sub.6 alkyl, wherein one or more of R.sup.a, R.sup.b, R.sup.c or R.sup.d may optionally be substituted by one to three groups as defined in claim 1.

13. A process according to claim 12, wherein the cation is selected from:
[N(R.sup.a)(R.sup.b)(R.sup.c)(R.sup.d)].sup.+, wherein: R.sup.a, R.sup.b, R.sup.c and R.sup.d are each independently selected from C.sub.1 to C.sub.4 alkyl, including C.sub.1, C.sub.2 and C.sub.4 alkyl, wherein at least one of R.sup.a, R.sup.b, R.sup.c or R.sup.d is substituted by a single OH group.

14. A process according to claim 13, wherein the cation is choline: ##STR00010##

15. A process according to any of claims 1 to 14, wherein the basic ionic liquid is immiscible in the glyceride oil.

16. A process according to any of claims 1 to 15, wherein the basic ionic liquid is soluble in water.

17. A process according to any one of claims 1 to 16, wherein the basic ionic liquid has a melting point of less than 150 C.

18. A process according to claim 1 or claim 2 wherein the basic ionic liquid is choline bicarbonate: ##STR00011##

19. A process according to claim 1 or claim 2 wherein the basic ionic liquid is choline lysinate.

20. A process according to any of claims 1 to 19 wherein the basic ionic liquid is unsupported.

21. A process according to any of claims 1 to 19 wherein the basic ionic liquid is supported.

22. A process according to claim 21 wherein the support is selected from silica, alumina, alumina-silica, carbon, activated carbon or a zeolite.

23. A process according to claim 22, wherein the support is silica.

24. A process according to any one of claims 21 to 23, wherein the basic ionic liquid is adsorbed onto the support in an ionic liquid:support mass ratio of from 10:1 to 1:10.

25. A process according to claim 24, wherein the basic ionic liquid is adsorbed onto the support in an basic ionic liquid:support mass ratio of from 1:2 to 2:1.

26. A process according to any of claims 1 to 25 wherein step (i) is carried out at a temperature of from ambient temperature to 50 C.

27. A process according to any one of claims 1 to 26, further comprising regenerating the basic ionic liquid from one or more neutralisation salts of a free fatty acid formed in step (i) and isolated from the treated glyceride oil, by way of a regeneration process.

28. A process according to any one of claims 1 to 27, further comprising regenerating a basic ionic liquid as defined in claim 1 from one or more neutralisation salts of a free fatty acid (FFA) formed in step (i) and isolated from the treated glyceride oil, regeneration comprising the steps of: (a) contacting the salt of the FFA with an acid which has a lower pKa than the FFA from which the salt of the FFA was formed; (b) obtaining a salt product formed in step (a) which does not comprise the conjugate base of the FFA as an anion; and (c) performing an anion exchange step on the salt product to obtain a basic ionic liquid comprising the desired basic anion.

29. A process according to claim 14, further comprising forming choline bicarbonate from one or more neutralisation salts of a free fatty acid, formed in step (i) and isolated from the treated glyceride oil, in a regeneration process, regeneration comprising the steps of: (a) contacting the choline salt of a free fatty acid with carbonic acid; and (b) obtaining choline bicarbonate from the reaction mixture.

30. A process according to claim 14, further comprising forming choline hydroxide from one or more neutralisation salts of a free fatty acid, formed in step (i) and isolated from the treated glyceride oil, by way of a regeneration process, regeneration comprising the steps of: (a) performing an hydrogenation of the choline salt of a free fatty acid in the presence of a suitable catalyst; (b) separating choline hydroxide formed in the hydrogenation step (a).

31. A process according to claim 29 or claim 30, wherein the choline salt of a free fatty acid is choline stearate.

32. A process according to any of claims 1 to 31, wherein the glyceride oil from step (i) of the process is a vegetable oil.

33. A process according to claim 32, wherein the vegetable oil is selected from coconut oil, corn oil, cottonseed oil, groundnut oil, olive oil, palm oil, rapeseed oil, rice bran oil, safflower oil, soybean oil and sunflower oil, or mixtures thereof.

34. A process according to claim 33, wherein the vegetable oil is palm oil, preferably crude palm oil.

35. A treated glyceride oil obtained by the process of claim 14, comprising between 0.1 and 25 wt. % of a choline based neutralisation salt.

36. A treated glyceride oil obtained by the process of claim 8, comprising between 0.1 and 25 wt. % of an anion selected from serinate, prolinate, histidinate, threoninate, valinate, asparaginate, taurinate and lysinate.

37. A treated glyceride oil according to claim 35 or claim 36, wherein the treated glyceride oil is a treated vegetable oil.

38. A treated glyceride oil according to claim 37, wherein the treated vegetable oil is selected from coconut oil, corn oil, cottonseed oil, groundnut oil, olive oil, palm oil, rapeseed oil, rice bran oil, safflower oil, soybean oil and sunflower oil, or mixtures thereof.

39. A treated glyceride oil according to claim 38, wherein the treated vegetable oil is a treated palm oil.

40. A process for improving the storage stability of a treated glyceride oil comprising adding to a treated glyceride oil containing less than 2 wt. % free fatty acids (FFA), a basic ionic liquid having a basic anion selected from hydroxide, alkoxide, alkylcarbonate, hydrogen carbonate, serinate, prolinate, histidinate, threoninate, valinate, asparaginate, taurinate and lysinate; and a cation selected from:
[N(R.sup.a)(R.sup.b)(R.sup.c)(R.sup.d)].sup.+, wherein: R.sup.a, R.sup.b, R.sup.c and R.sup.d are each independently selected from hydrogen, a C.sub.1 to C.sub.8, straight chain or branched alkyl group or a C.sub.3 to C.sub.6 cycloalkyl group, wherein said alkyl or cycloalkyl groups are unsubstituted or may be substituted by one to three groups selected from: C.sub.1 to C.sub.4 alkoxy, C.sub.2 to C.sub.8 alkoxyalkoxy, C.sub.3 to C.sub.6 cycloalkyl, OH, SH, CO.sub.2(C.sub.1 to C.sub.6)alkyl, OC(O)(C.sub.1 to C.sub.6)alkyl, or any two of R.sup.a, R.sup.b, R.sup.c and R.sup.d combine to form an alkylene chain (CH.sub.2).sub.q wherein q is from 3 to 6.

41. A process according to claim 40, wherein the treated glyceride oil contains less than 0.5 wt. % FFA.

42. A process according to claim 40 or claim 41, wherein the basic anion is as defined in any of claims 3 to 11.

43. A process according to any of claim 40 to claim 41, wherein the cation is as defined in any of claims 12 to 14.

44. A process according to claim 40 or claim 41 wherein the basic ionic liquid is choline lysinate.

45. A process according to any of claims 40 to 44 further comprising adding a base anion exchange resin to the treated glyceride oil.

46. A process according to claim 45 wherein the base anion exchange resin comprises a styrene divinylbenzene copolymer.

47. A process according to any of claims 40 to 46, wherein the treated glyceride oil is a treated vegetable oil.

48. A process according to claim 47, wherein the treated vegetable oil is selected from coconut oil, corn oil, cottonseed oil, groundnut oil, olive oil, palm oil, rapeseed oil, rice bran oil, safflower oil, soybean oil and sunflower oil, or mixtures thereof.

49. A process according to claim 48, wherein the treated vegetable oil is a treated palm oil.

50. A glyceride oil composition comprising treated glyceride oil containing less than 2 wt % free fatty acids (FFA), preferably less than 0.5 wt. % FFA, and a basic ionic liquid having a basic anion selected from hydroxide, alkoxide, alkylcarbonate, hydrogen carbonate, serinate, prolinate, histidinate, threoninate, valinate, asparaginate, taurinate and lysinate; and a cation selected from:
[N(R.sup.a)(R.sup.b)(R.sup.c)(R.sup.d)].sup.+, wherein: R.sup.a, R.sup.b, R.sup.c and R.sup.d are each independently selected from hydrogen, a C.sub.1 to C.sub.8, straight chain or branched alkyl group or a C.sub.3 to C.sub.6 cycloalkyl group, wherein said alkyl or cycloalkyl groups are unsubstituted or may be substituted by one to three groups selected from: C.sub.1 to C.sub.4 alkoxy, C.sub.2 to C.sub.8 alkoxyalkoxy, C.sub.3 to C.sub.6 cycloalkyl, OH, SH, CO.sub.2(C.sub.1 to C.sub.6)alkyl, OC(O)(C.sub.1 to C.sub.6)alkyl, or any two of R.sup.a, R.sup.b, R.sup.c and R.sup.d combine to form an alkylene chain (CH.sub.2).sub.q wherein q is from 3 to 6.

51. A composition according to claim 50 wherein the basic anion is as defined in any of claims 3 to 11.

52. A composition according to claim 50 or claim 51 wherein the cation is as defined in any of claims 12 to 14.

53. A composition according to claim 50 wherein the basic ionic liquid is choline lysinate.

54. A composition according to any of claims 50 to 53 further comprising a base anion exchange resin.

55. A composition according to claim 54 wherein the base anion exchange resin comprises a styrene divinylbenzene copolymer.

56. A composition according to any of claims 50 to 55 comprising between 0.1 and 25 wt. % basic ionic liquid.

57. A composition according to any of claims 50 to 56, wherein the treated glyceride oil is selected from a treated vegetable oil.

58. A treated glyceride oil according to claim 57, wherein the treated vegetable oil is selected from coconut oil, corn oil, cottonseed oil, groundnut oil, olive oil, palm oil, rapeseed oil, rice bran oil, safflower oil, soybean oil and sunflower oil, or mixtures thereof.

59. A treated glyceride oil according to claim 58, wherein the treated vegetable oil is a treated palm oil.

Description

[0153] The present invention will now be illustrated by way of the following examples and with reference to the following figures:

[0154] FIG. 1: Graphical representation of the viscosity of crude and palm oil treated according to the process of the invention at varying temperature.

[0155] FIG. 2: Graphical representation of thermal degradation of palm oil stored at 60 C. different samples: treated palm oil (PO), treated palm oil saturated with water (POH.sub.20), treated palm oil containing AMBERLITE (Trade Mark) IRA96 (IRA96), treated palm oil containing molecular sieves (POMO) and treated palm containing choline lysinate (POCHOLL).

[0156] FIG. 3: Graphical representation of thermal degradation of palm oil stored at 90 C. different samples: treated palm oil (PO), treated palm oil saturated with water (POH.sub.2O), treated palm oil containing AMBERLITE (Trade Mark) IRA96 (IRA96), treated palm oil containing molecular sieves (POMO) and treated palm containing choline lysinate (POCHOLL).

EXAMPLES

Determination of FFA Content in Palm Oil

[0157] To a beaker containing 60 ml of isopropyl alcohol was added 0.5 mL of phenolphthalein. This mixture was heated until boiling and 0.02M potassium hydroxide in isopropyl alcohol was added until a faint pink colour persisted for approximately 10 s.

[0158] To a glass vial was added 0.200 g of palm oil which was subsequently dissolved in 50 ml of the above hot isopropyl alcohol solution. The resulting solution was titrated whilst stirring with 0.02M potassium hydroxide solution using a 25 ml burette graduated in 0.1 ml to the end point of the phenolphthalein indicator i.e until the pink colour persisted for at least 30 s.

[0159] Content of FFA was subsequently calculated using the formula:

28.4MV/m

where:
V is the volume (ml) of potassium hydroxide solution used;
M the molarity of the potassium hydroxide solution; and
m is the mass (g) of the palm oil sample.
Removal of FFA from Palm Oil Using Basic Ionic Liquid

Example 1

[0160] Following the above described titration method, palm oil obtained from a third party supplier was found to contain 1.584 wt. % FFA. The palm oil was subsequently doped with stearic acid to give an FFA content of 7.74 wt. %. A 40 g sample was heated to 40 C. and then added to 2.250 g of an aqueous choline bicarbonate solution (80 w/w %) obtained from Aldrich. The mixture was rapidly stirred for 5 minutes after which the evolution of CO.sub.2 had ceased. The mixture was then centrifuged at 2500 rpm for 10 minutes.

[0161] The upper oil phase was removed, titrated and found to contain 0.251 wt. % FFA and 0.012 wt. % water. The lower aqueous phase was found to contain choline stearate. .sup.1H NMR showed no evidence of choline stearate in the upper oil phase.

[0162] Viscosities of the crude palm doped with strearic acid and the treated palm oil obtained were determined at various temperatures. The results are shown graphically in FIG. 1, and indicate that the viscosity of the treated palm oil is significantly reduced at lower temperature compared with the crude palm oil following removal of FFA.

Palm Oil Stability Testing

Example 2

[0163] Samples of the treated palm oil having reduced content of FFA from Example 1 were taken and stored at different temperatures (60 C. and 90 C.) in a thermostatically controlled oven. Data was collected periodically over 30 a day period. The long term stability of the treated palm oil was tested alone and in the presence of certain additives as indicated below: [0164] 1. No additive [0165] 2. Water [0166] 3. Free base polymer amberlite [0167] 4. Molecular sieves (water scavenger) [0168] 5. Choline lysinate (Basic ionic liquid and acid scavenger)

[0169] Sample 2 above corresponds to a palm oil composition which is saturated with water at 0.174 w/w %. All additives in samples 3 to 5 above were added at a rate of 4 wt % based on the palm oil.

[0170] Tables 1 and 2 below show the FFA content (wt. %) of palm oil for samples 1 to 5 held at temperatures of 60 C. and 90 C. respectively for different time intervals.

TABLE-US-00001 TABLE 1 Samples stored at 60 C. Sample No. 0 days 2 days 5 days 12 days 30 days 1 0.124 0.404 0.896 1.12 1.560 2 0.124 0.453 0.969 1.075 1.860 3 0.124 0.505 0.679 0.701 0.742 4 0.124 0.284 0.395 0.814 5 0.124 0.190 0.485 0.506 0.545

TABLE-US-00002 TABLE 2 Samples stored at 90 C. Sample No. 0 days 2 days 5 days 12 days 30 days 1 0.124 0.672 0.868 1.117 2.080 2 0.124 0.774 1.087 2.626 4.516 3 0.124 0.331 0.465 0.520 0.554 4 0.124 0.401 0.994 1.521 5 0.124 0.351 0.313 0.390 0.413

[0171] The above results show that significant thermal degradation of the palm oil occurs at both 60 C. and 90 C. for samples 1 and 2, which contain no additive or are saturated with water respectively, as demonstrated by the formation of FFA over time. The combination of water in the palm oil (sample 2) and higher temperature (90 C.) results in significantly increased degradation of the oil, with the content of FFA reaching 4.516 wt. %.

[0172] In contrast, sample 5 containing basic ionic liquid according to the present invention (choline lysinate) suppresses oil degradation by neutralising FFA such that the FFA content is maintained well below 1 wt. %. The content of FFA in sample 5 after 30 days at 60 C. is 0.545 wt. % whilst only 0.413 wt. % after 30 days at 90 C. This is improved over the presence of only water scavenging molecular sieves (sample 3), particularly at storage at 90 C. where FFA content increased to 1.5 wt. % after 12 days.