Process for the preparation of fatty acids

1. Process for the preparation of a material comprising conjugated isomers of a polyunsaturated fatty acid, which comprises:

treating a first fatty acid mixture, comprising saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids in the presence of ethanol to form (i) a solid fraction and (ii) a liquid fraction comprising a second fatty acid mixture, wherein the second fatty acid mixture has a higher molar ratio of total polyunsaturated fatty acids to total saturated and monounsaturated fatty acids than the first fatty acid mixture;

separating the solid fraction and the liquid fraction; and

subjecting the second fatty acid mixture or a derivative or reaction product thereof to treatment with a base in the presence of a solvent, to form conjugated isomers of at least some of the polyunsaturated fatty acids.

2. Process as claimed in claim 1 , wherein the material comprises at least 90% by weight of conjugated isomers of polyunsaturated fatty acids.

3. Process as claimed in claim 1 or claim 2 , wherein the polyunsaturated fatty acids contain from 12 to 24 carbon atoms.

4. Process as claimed in claim 1 , wherein the saturated fatty acids, the monounsaturated fatty acids, and the polyunsaturated fatty acids contain 18 carbon atoms.

5. Process as claimed in claim 1 , wherein the conjugated isomers are conjugated isomers of linoleic acids.

6. Process as claimed in claim 1 , wherein the first fatty acid fraction is treated with urea and the solid fraction comprises urea.

7. Process as claimed in claim 1 , wherein the first fatty acid mixture is treated in the presence of a solvent comprising at least 80% by weight ethanol.

8. Process as claimed in claim 1 , wherein the second fatty acid mixture is subjected to further process steps prior to treatment with the base to form a derivative or reaction product thereof.

9. Process as claimed in claim 8 , wherein the further steps are selected from purification, removal of solvent, esterification to form C 1 to C 6 alkyl esters of the fatty acids and combinations thereof.

10. Process as claimed in claim 1 , wherein the first fatty acid mixture is obtained from an oil comprising from 50% to 85% by weight based on total fatty acids of fatty acids containing 18 carbon atoms.

11. Process as claimed in claim 1 , wherein the first fatty acid mixture is obtained by a method comprising the hydrolysis of vegetable oil with a base in the presence of ethanol as solvent.

12. Process as claimed in claim 11 , wherein the vegetable oil is selected from the group consisting of safflower oil, sunflower oil, rape seed oil, cotton seed oil, soybean oil and linseed oil.

13. Process as claimed in claim 1 , wherein the solvent comprises an alcohol having three carbon atoms and at least two hydroxyl groups.

14. Process as claimed in claim 1 , wherein the solvent is propylene glycol.

15. Process as claimed in claim 1 , which comprises acidifying the second first fatty acid mixture after treatment with a base.

16. Process as claimed in claim 15 , wherein at least a proportion of the salts formed on acidifying is removed and the resulting mixture is subsequently purified.

17. Process as claimed in claim 1 , further comprising the step of forming a mono-, di- or triglyceride of the conjugated isomers polyunsaturated fatty acids.

18. The method for the separation of polyunsaturated fatty acids from mixtures containing polyunsaturated fatty acids together with saturated and monounsaturated fatty acids which comprises crystallisation with urea in the presence of ethanol as a solvent.