Method for producing oil from microalgal products

Abstract

The invention relates to a process for producing an oil, in particular an edible oil, having a high content of unsaturated fatty acids from a microalgae preparation. According to the invention, the microalgae preparation is treated to form an intermediate product, and the intermediate product is subjected to a substance separation for separating off impurities, with triglycerides being used as a carrier for the impurities. As a microalgae preparation, advantageously a microalgae oil and / or a lipid extract is used. The microalgae preparation is preferably obtained from microalgae, in particular photoautotrophic and / or mixotrophic microalgae. In one embodiment of the invention, the microalgae preparation is treated by transesterification to form the intermediate product, wherein the microalgae preparation is preferably converted into ethyl esters. In one embodiment of the invention, the organic phase of the intermediate product is separated off from the inorganic phase, and the organic phase of the intermediate product is subjected to a substance separation for separating off impurities, with triglycerides being used.

Description

Field of the invention

[0001] The present invention relates to a method for producing an oil, in particular a consumable oil, having a high content of unsaturated fatty acids from a microalgae product.

[0002] Algal oil can be produced from photo- and / or mixotrophic microalgae, which is currently not suitable as a consumable oil because it forms a black paste containing chlorophyll, pigments and other fat-soluble substances. The flowability and composition of the oil depend on the type of microalgae, the cultivation conditions and the harvesting process. So far, the microalgae biomass has been pretreated by means of freeze-drying or spray-drying and then extracted by means of solvent extraction or supercritical fluid extraction. However, there is great interest in the production of consumable oils from microalgae, since these contain relatively high amounts of omega-3-fatty acids, in particular eicosapentaenoic acid (EPA). SUMMARY

[0003] It is an object of the present invention to provide a method which allows the production of a consumable oil from a microalgae oil.

[0004] According to the invention, this object is achieved by treating a microalgae product to form an intermediate product and carrying out a substance separation for separating impurities, wherein triglycerides are used as a carrier for the impurities.

[0005] Surprisingly, it has been shown that a substance separation by means of triglycerides makes it possible to produce a pure oil having a high content of omega-3-fatty acids from a microalgae product at relatively low cost, which is suitable for use as a consumable oil.

[0006] Advantageously, more than 80% of the impurities can be removed from the microalgae product by means of the method. More than 90%, if appropriate more than 95%, of the impurities are removed in each case depending on the method progress.

[0007] Conveniently, a microalgae oil and / or a lipid extract is used as the microalgae product. Preferably, the microalgae oil or the lipid extract is obtained from photo- and / or mixotrophic microalgae.

[0008] A lipid extract from green algae or a single-cell photosynthetic organism has proven to be particularly suitable for carrying out the method.

[0009] Preferably, the microalgae product has an EPA content of at least 15% by weight, preferably an EPA content of at least 20% by weight, particularly preferably at least 30% by weight.

[0010] In one embodiment, the microalgae product has a pigment content, in particular a chlorophyll content, of more than 15000 mg / 100 g, if appropriate more than 20000 mg / 100 g.

[0011] In one embodiment of the application, the microalgae product is treated by transesterification to form an intermediate product. Conveniently, the microalgae product is converted into ethyl esters. This process step serves to prepare the intermediate product for increasing the concentration of omega-3-fatty acids, in particular EPA and / or DHA (docosahexaenoic acid).

[0012] Conveniently, the microalgae product is chemically and / or enzymatically neutralized and / or dephosphorylated.

[0013] In another embodiment of the application, the microalgae product is added to a solvent for ester exchange. The microalgae product can be completely or at least partially soluble in water and / or organic solvents, in particular polar or non-polar liquids. For example, the microalgae product can be soluble in ethanol or hexane and partially soluble in water.

[0014] For the transesterification, it has proven advantageous to use a catalyst. Acids such as sulfuric acid have proven suitable, in particular anhydrous acids. The transesterification reaction is preferably carried out at temperatures < 100°C, particularly preferably < 80°C, for a duration of > 30 minutes, preferably > 60 minutes, particularly preferably > 300 minutes.

[0015] In one embodiment of the application, in particular after the transesterification, the intermediate product is subjected to a substance separation to remove impurities. Conveniently, triglycerides are added to the intermediate product (preferably after the transesterification) for the substance separation.

[0016] In one embodiment of the application, the organic phase of the intermediate product is separated from the inorganic phase, preferably by mechanical separation, in particular preferably by sedimentation and / or centrifugation. To this end, it is advantageous to add a (in particular organic) solvent to the intermediate product. The mechanical separation can be carried out, for example, by means of sedimentation, sedimentation or centrifugation.

[0017] The inorganic phase separated in the process can be subjected to the above-mentioned transesterification again (and if appropriate several times) in order to separate the organic phase remaining therein.

[0018] The organic phase is also separated. The remainder forms the intermediate product in the form of ethyl esters.

[0019] In one particularly preferred embodiment of the application, the organic phase of the intermediate product is subjected to a thermal substance separation to remove impurities. Such impurities can consist of pigments, in particular chlorophyll, phycoerythrin and / or carotenoids, for example carotenes and xanthophylls.

[0020] In the thermal substance separation, it is advantageous to use triglycerides, preferably triglyceride oil.

[0021] Surprisingly, it has proven particularly suitable for triglycerides to act as a carrier for removing impurities, in particular pigments that darken the oil.

[0022] The thermal separation of the substances for removing the impurities is preferably carried out by means of distillation, preferably molecular distillation. It has proved to be particularly advantageous to carry out the molecular distillation at a pressure of 0.001 to 1 mbar. This allows a particularly gentle treatment of the intermediate product, since it reduces the boiling temperature of the individual components and the distillation can be carried out at a relatively low temperature.

[0023] Advantageously, the intermediate product is mixed with triglycerides, in particular triglyceride oil, in a mass ratio of between 1 :0.1 and 1 :15, preferably in a mass ratio of 1 :0.5 to 1 :7, particularly preferably in a mass ratio of 1 :1 to 1 :5.

[0024] Advantageously, the molecular distillation is carried out in a temperature range of 100°C to 190°C, preferably 130°C to 175°C. In the distillation, in particular molecular distillation, the lipids are preferably left in the ethyl esters which constitute the distillate, and the triglycerides containing the impurities are removed therefrom.

[0025] The concentration of the omega-3-fatty acids in the intermediate product thus obtained is advantageously increased by means of an additional process which increases the concentration of omega-3-fatty acids. The concentration-increasing process can be distillation, in particular molecular distillation, silver salt extraction, liquid chromatography, in particular supercritical liquid chromatography (SFC) and / or precipitation, in particular by means of urea.

[0026] In a preferred embodiment of the application, the saturated fatty acids are separated from the intermediate product, in particular after the thermal separation of the substances, preferably by adding urea, in particular urea crystals.

[0027] After the separation of the saturated fatty acids, the intermediate product is advantageously purified by thermal separation of the substances in order to remove the impurities, in particular urea, which remain from the concentration-increasing process. The intermediate product esters can then be converted into triglycerides by means of transesterification.

[0028] In another embodiment of the application, an antioxidant is added to the intermediate product after the separation of the saturated fatty acids or after the conversion of the esters into triglycerides. The antioxidant serves to bleach the intermediate product. Preferably, a naturally occurring antioxidant is used. A clay which is used in various food production processes has proved to be suitable for this purpose.

[0029] By means of the process according to the application, it is possible to produce an oil having an EPA content of more than 50% by weight, preferably more than 60% by weight, particularly preferably more than 70% by weight.

[0030] It has been shown to be particularly advantageous to prepare the oil in such a way that the pigment content, in particular the chlorophyll content, of the oil is < 4000 mg / 100 g, preferably < 3000 mg / 100 g.

[0031] Particular embodiments

[0032] The application is described in more detail below with reference to examples.

[0033] 1. Example:

[0034] For the process described below for producing an edible oil with a high content of omega-3-fatty acids, an oil paste obtained from microalgae of the genus Nannochloropsis is used as the microalgae product. The oil paste is analyzed using high-performance liquid chromatography (HPLC) and gas chromatography. The following contents are determined therefrom:

[0035]

[0036] First, the oil paste is released from the phospholipids by enzymes.

[0037] Subsequently, transesterification to ethyl esters is carried out. For this purpose, 100 g of the oil paste and 300 g of ethanol are added to a reactor. Sulfuric acid is added as a catalyst under continuous stirring. The resulting solution is heated to 80°C and the reaction is continued for 80 minutes.

[0038] Subsequently, the solution is cooled and after cooling cyclohexane and water are added to separate the organic phase from the inorganic phase. The resulting solution is left to stand until a separation between the organic and inorganic phases is formed. The inorganic phase is distributed at the bottom end so that the organic phase can be poured off.

[0039] The remaining inorganic phase can be treated again, and if appropriate several times, with cyclohexane.

[0040] The organic phase obtained is distilled and the ethyl esters are obtained therefrom as an intermediate product. The oil produced and formed by the transesterification has an ethyl ester concentration of 85% by weight. It has an EPA concentration of 38% by weight and is dark green in color.

[0041] Subsequently, the intermediate product is subjected to molecular distillation in order to remove the impurities which cause the dark green color. In the present example, the molecular distillation is carried out at 0.01 mbar in order to keep the boiling point of the intermediate product components low. For the molecular distillation, the oil which constitutes the intermediate product is mixed with a triglyceride oil in a mass ratio of 1 :3 and is subjected to distillation at 150°C. After the molecular distillation, the lipids remain in the oil containing the ethyl esters. The impurities, in particular the pigments which previously dyed the oil dark green, remain in the triglycerides and are separated off in the residue stream.

[0042] The oil obtained as a further intermediate product is yellow to orange in color. This oil contains at least 90% by weight of ethyl esters and has an EPA concentration of 38% by weight.

[0043] Subsequently, the content of saturated fatty acids is reduced by means of precipitation with urea. For this purpose, the intermediate product is mixed with urea crystals and ethanol, and the mixture is continuously stirred at 80°C for 90 minutes. The resulting solution is then cooled and filtered. To rinse the urea residues, the remaining solution is mixed with brine.

[0044] As a further intermediate product, an oil with an EPA concentration of 67% by weight is obtained.

[0045] For further purification, the intermediate product can be subjected to further molecular distillation. In the present example, the intermediate product is treated at a pressure of 0.03 mbar and at 160°C.

[0046] For the final bleaching, clay is added to the intermediate product as an antioxidant at a temperature of 65°C and at a pressure of 3 mbar, and residual impurities and peroxides are removed. Subsequently, the clay is removed by means of filtration.

[0047] The final product of the oil paste is an oil with an EPA concentration of 67% by weight, which is suitable for consumption by humans.

[0048] 2. Example:

[0049] The process steps described above have been carried out in further experiments with another oil paste as starting material.

[0050] The following contents have been determined for this oil paste:

[0051] Triglycerides: 29.1% by weight

[0052] Monoglycerides + diglycerides: 34.2% by weight

[0053] Lipids (free fatty acids, sphingolipids, glycolipids, galactolipids, phospholipids):

[0054] 36.6% by weight

[0055] EPA: 24.9% by weight

[0056] The final product of the oil paste is an oil with an EPA concentration of 45% by weight. This oil is also suitable as food for humans.

Claims

1. A method for producing oil having a high content of unsaturated fatty acids from a microalgal product, characterized by, The microalgae product is subjected to transesterification to form an intermediate product, and after transesterification, triglyceride is added to the intermediate product, the intermediate product to which the triglyceride is added is distilled to remove impurities, wherein the triglyceride serves as a carrier of the impurities, the intermediate product is mixed with the triglyceride at a mass ratio of 1:0.1 to 1:15, the microalgae product is a lipid extract, and the impurities are pigments.

2. The method of claim 1, wherein, The microalgae product is a microalgae oil.

3. The method of claim 1, wherein, The oil having a high content of unsaturated fatty acids is an edible oil.

4. The method of claim 1, wherein, The intermediate product is mixed with the triglyceride at a mass ratio of 1:0.5 to 1:

7.

5. The method of claim 1, wherein, The intermediate product is mixed with the triglyceride at a mass ratio of 1:1 to 1:

5.

6. The method of claim 1, wherein, After the removal of the impurities by distillation, saturated fatty acids are further separated from the distilled intermediate product.

7. The method of claim 6, wherein, The saturated fatty acids are separated from the distilled intermediate product by urea.

8. The method of claim 7, wherein, After the separation of the saturated fatty acids, the intermediate product is subjected to thermal separation purification of substances to remove the remaining urea.

9. The method of claim 8, wherein, The intermediate product is converted into triglyceride by transesterification after the removal of the remaining urea.

10. The method of claim 6, wherein, An antioxidant is added to the intermediate product for bleaching after the separation of the saturated fatty acids.

11. The method of claim 9, wherein An antioxidant is added to the intermediate product for bleaching after the conversion into triglyceride by transesterification.

12. The method according to claim 10 or 11, wherein the antioxidant added is a swellable phyllosilicate.

13. The method according to claim 10 or 11, wherein the antioxidant added is bleaching earth or activated carbon.

14. The method according to claim 10 or 11, wherein the antioxidant is a naturally occurring antioxidant.

15. The method of claim 1, wherein, The obtained oil has an EPA content of greater than 50% by weight.

16. The method of claim 15, wherein, The obtained oil has an EPA content of greater than 60% by weight.

17. The method of claim 1, wherein, The obtained oil has a pigment content of <4000 mg / 100 g.

18. The method of claim 17, wherein, The obtained oil has a pigment content of <3000 mg / 100 g.

19. The method of claim 17, wherein, The pigments are chlorophyll.

20. An oil having a high content of unsaturated fatty acids produced from a microalgae product, obtainable by the method of any one of claims 1 to 19.

21. The oil according to claim 20, wherein the microalgae is a photoautotrophic and / or mixotrophic microalgae.

22. The oil of claim 20, wherein, The oil has an EPA content of greater than 50% by weight.

23. The oil of claim 20, wherein, The oil has an EPA content of greater than 60% by weight.

24. The oil of claim 20, wherein, The oil has a pigment content of <4000 mg / 100 g.

25. The oil of claim 20, wherein, The oil has a pigment content of <3000 mg / 100 g.

26. The oil according to claim 24 or 25, characterized in that, The pigments are chlorophyll.

Images