METHOD FOR PRODUCING OIL FROM A MICROALGAE PRODUCT

Abstract

A method for producing edible oil, having a high content of unsaturated fatty acids, from a product of microalgae. The microalgae product is treated to form an intermediate product that is subjected to a material separation process for removing impurities, in which material separation process the triglyceride is used as a carrier for the impurities. A microalgae oil and/or a lipid extract is advantageously used as the microalgae product. The microalgae product is preferably obtained from microalgae, more particularly photoautotrophic and/or mixotrophic microalgae. The microalgae product is treated by transesterification in order to form the intermediate product, wherein the microalgae product is preferably transformed into an ethyl ester. An organic phase is separated from an inorganic phase of the intermediate product and the organic phase of the intermediate product is subjected to a material separation process for removing impurities, in which material separation process the triglyceride is used.

Claims

1-19. (canceled)

20. A method for producing oil, especially edible oil, having a high content of unsaturated fatty acids, from a product of microalgae, comprising the steps of: treating the microalgae product to form an intermediate product;, and subjecting the intermediate product to a material separation process for removing impurities, in which triglyceride is used as carrier for the impurities.

21. The method according to claim 20, including using a microalgae oil and/or a lipid extract as the microalgae product and obtaining the microalgae product from phototrophic and/or mixotrophic microalgae, wherein the microalgae product has a content of at least 20% by weight EPA.

22. The method according to claim 20, wherein treating step includes treating the microalgae product by transesterification to form the intermediate product, wherein the microalgae product is converted to an ethyl ester.

23. The method according to claim 20, wherein the material separation process includes adding the triglyceride to the intermediate product.

24. The method according to claim 20, including separating an organic phase from an inorganic phase of the intermediate product mechanical separation.

25. The method according to claim 24 including subjecting the organic phase of the intermediate product to a thermal material separation process for removing impurities.

26. The method according to claim 25, wherein in the thermal material separation process, the triglyceride is used as the carrier for the impurities.

27. The method according to claim 25, including carrying out the thermal material separation process for removing impurities by distillation.

28. The method according to claim 20, including separating saturated fatty from the intermediate product.

29. The method according to claim 28, including subjecting the intermediate product, after separation of the saturated fatty acids for purification to a thermal material separation process for removing remaining impurities.

30. The method according to claim 29, including converting the intermediate product, after the thermal material separation process, to a triglyceride by transesterification.

31. The method according to claim 20, including adding an antioxidant to the intermediate product.

32. The method according to claim 31, wherein swellable layered silicate or activated carbon is added as the antioxidant.

33. The method according to claim 20, wherein the oil produced has an EPA content of more than 50% by weight.

34. The method according to claim 20, wherein the oil produced has a pigment content of < 4000 mg/100 g.

35. The method according to claim 34, wherein the oil produced has a chlorophyll content of < 3000 mg/100 g.

36. A microalgae oil having a high content of unsaturated fatty acids, which has been produced from a product made from microalgae, comprising an EPA content of more than 50% by weight and a pigment content of < 4000 mg/100 g.

37. The microalgae oil according to claim 36, wherein the EPA content is more than 60% by weight.

38. The microalgae oil according to claim 36, wherein the pigment content is < 3000 mg/100 g.

39. An oil having a high content of unsaturated fatty acids, which has been produced from a product of microalgae, obtained by the method according to claim 20.

40. The oil according to claim 39, wherein the oil has an EPA content of more than 50% by weight and a pigment content of < 4000 mg/100 g.

Description

[0029] The invention is described in more detail below by way of a working example.

1.SUP.ST EXAMPLE:

[0030] For the method described below for producing an edible oil having a high content of omega-3 fatty acid, an oil paste obtained from microalgae of the genus Nannochloropsis was used as the microalgae product. The oil paste was analyzed by means of High Performance Liquid Chromatography (HPLC) and gas chromatography. The following contents were determined:

TABLE-US-00001 Triglycerides: 29.2% by weight Diglycerides: 26.4% by weight Monoglycerides: 3.5% by weight Lipids (free fatty acids, sphingolipids, glycolipids, galactolipids, phospholipids): 40.9% by weight EPA: 36.8% by weight

[0031] First, the oil paste was enzymatically freed from phospholipids.

[0032] Subsequently, a transesterification to ethyl ester is carried out. For this purpose, 100 g of the oil paste was added to a reactor with 300 g of ethanol. Sulfuric acid was added as a catalyst with continuous stirring. The resulting solution was heated to 80° C. and the reaction was allowed to proceed for 80 min.

[0033] The solution was then cooled and, after cooling, cyclohexane and water were added to separate the organic phase from the inorganic phase. The solution obtained is left to stand until the organic and inorganic phases separate. The inorganic phase settles at the bottom, so that the organic phase can be poured off.

[0034] The remaining inorganic phase can be treated again with cyclohexane, several times if necessary. The organic phases obtained are distilled and thereby the ethyl ester is obtained as an intermediate product. The oil which has been produced by the transesterification and forms the intermediate product has a concentration of 85% by weight ethyl ester. It has an EPA concentration of 38% by weight and is dark green in color.

[0035] Subsequently, the intermediate product is subjected to molecular distillation to remove impurities which, inter alia, result in the dark green color. In the present example, the molecular distillation was carried out at 0.01 mbar in order to keep the boiling temperature of the components of the intermediate product low. For the molecular distillation, the oil forming the intermediate product is mixed with a triglyceride oil at a mass ratio of 1:3 and the distillation is carried out at 150° C. After molecular distillation, the lipids remain in the oil comprising the ethyl ester, and the impurities, especially the pigments that previously colored the oil dark green, remain in the triglyceride, which is separated with the residual stream.

[0036] An oil is obtained as further intermediate product, which has a yellow to orange color. The oil comprises at least 90% by weight ethyl ester and has an EPA concentration of 38% by weight.

[0037] Subsequently, precipitation is carried out using urea to reduce the content of saturated fatty acids. For this purpose, the intermediate product is mixed with urea crystals and ethanol and the mixture is stirred continuously at 80° C. for 90 minutes. The solution obtained is then cooled and filtered. Brine is added to the remaining solution to wash out residual urea. As a further intermediate product there is now an oil present having an EPA concentration of 67% by weight.

[0038] For further purification, the intermediate product may be subjected to a further molecular distillation. In the present working example, the intermediate product was treated at a pressure of 0.03 mbar and at 160° C.

[0039] For the final bleaching, clay was added to the intermediate product as an antioxidant and any remaining impurities and peroxides were removed at 65° C. and at a pressure of 3 mbar. The clay was then separated off by filtration.

[0040] The final product obtained from the oil paste was an oil having an EPA concentration of 67% by weight, which is suitable for human consumption.

2.SUP.ND EXAMPLE:

[0041] The method steps described above were carried out in a further experiment with another oil paste as starting material.

[0042] The contents specified below were determined for the oil paste:

TABLE-US-00002 Triglycerides: 29.1% by weight Monoglycerides + diglycerides: 34.2% by weight Lipids (free fatty acids, sphingolipids, glycolipids, galactolipids, phospholipids): 36.6% by weight EPA: 24.9% by weight

[0043] The final product obtained from the oil paste was an oil having an EPA concentration of 45% by weight. The oil is likewise suitable for human consumption.