A kind of preparation method of polyunsaturated fatty acid ester

Abstract

The present invention relates to the technical field of polyunsaturated fatty acid ester synthesis, and in particular to a method for preparing polyunsaturated fatty acid ester. In the preparation method provided by the present invention, phospholipid-type polyunsaturated fatty acids are prepared by enzymatic reaction of raw materials including the following components: polyunsaturated fatty acid esters, polyunsaturated fatty acid salts, phospholipids and lipase, wherein the polyunsaturated fatty acids corresponding to the polyunsaturated fatty acid esters are of the same type as the polyunsaturated fatty acids corresponding to the polyunsaturated fatty acid salts. The method has a wide selection of raw materials, is independent of organic solvents, is applicable to a variety of reaction environments, can achieve a high fatty acid access rate in a system without organic solvents, and the content of polyunsaturated fatty acids in the prepared phospholipid-type polyunsaturated fatty acids is significantly improved, which is suitable for large-scale promotion and application.

Description

Technical Field

[0001] The invention relates to the technical field of polyunsaturated fatty acid ester synthesis, and in particular to a method for preparing phospholipid type polyunsaturated fatty acids. Background Art

[0002] Ester products of polyunsaturated fatty acids (PUFA) are usually divided into ethyl ester type, triglyceride type and phospholipid type. The physiological functions of PUFA vary due to their different molecular forms in fat. PUFA in the form of phospholipids not only has the physiological functions of phospholipids and PUFA, but also has a more stable structure, is not easy to oxidize, and is more conducive to human absorption. Studies have shown that the absorption rate of ethyl ester DHA in the human body is only about 20%, the absorption rate of glycerol DHA in the human body can be increased to 70%, and the absorption rate of phospholipid DHA in the human body is the highest, exceeding 99%.

[0003] Natural EPA / DHA-rich phospholipids are mainly found in marine animals, and their production is far from meeting people's needs. Artificial synthesis of phospholipid-type PUFA has become another way to obtain them. To change the fatty acid composition of phospholipids, you can generally choose transesterification or acidolysis. Transesterification is the exchange of ester compounds of target fatty acids with fatty acids on phospholipids under the action of enzymes; acidolysis is the exchange of free fatty acids with fatty acids on phospholipids. At present, under acidolysis, a relatively satisfactory fatty acid access rate can often be obtained. Although the enzymatic transesterification reaction is more green and environmentally friendly, its access effect is often difficult to achieve the same effect as that of acidolysis.

[0004] Chinese invention patent CN104962590 A discloses a microbial-derived phospholipid-type polyunsaturated fatty acid oil and a preparation method thereof, wherein the method uses lipase-catalyzed transesterification of docosahexaenoic acid-containing oil and powdered phospholipid to prepare microbial-derived phospholipid-type polyunsaturated fatty acid oil. However, the method involves a two-step enzymatic method, which is cumbersome in reaction and high in production cost.

[0005] Chinese invention patent CN106893747A discloses a method for preparing n-3 polyunsaturated fatty acid phospholipids by enzymatically catalyzing the transesterification of n-3 polyunsaturated fatty acids or their ester derivatives with soybean lecithin. However, the enzymatic reaction can only achieve good results with the participation of an organic solvent, and the access rate without the participation of a solvent is less than 10%. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing polyunsaturated fatty acid esters, specifically a method for preparing phospholipid polyunsaturated fatty acids. The method does not rely on the addition of organic solvents during the preparation of phospholipid polyunsaturated fatty acids, and has a good fatty acid access effect.

[0007] The present invention aims at the problem that the ester exchange reaction in the prior art to prepare phospholipid polyunsaturated fatty acids mostly needs to rely on the solvent system formed by the organic solvent, and after removing the organic solvent, it is impossible to ensure a good fatty acid access rate, and develops a method for preparing phospholipid polyunsaturated fatty acids that is efficient and independent of the organic solvent system. The present invention found in the research and development process that the organic solvent system is very critical to ensure the high access rate of fatty acids in the preparation process of phospholipid polyunsaturated fatty acids. After removing the organic solvent, even if the reaction system is optimized in many aspects and the substances disclosed in the prior art that may be beneficial to promote the ester exchange reaction are added, it is difficult to achieve the fatty acid access rate under the condition of the presence of organic solvent. The present invention unexpectedly found that the introduction of polyunsaturated fatty acid salts corresponding to polyunsaturated fatty acid esters in the reaction system can significantly improve the access rate of fatty acids in the solvent-free system, thereby increasing the content of fatty acids in the prepared phospholipid polyunsaturated fatty acids. The present invention also found that the introduction of polyunsaturated fatty acid salts can achieve a good fatty acid access rate whether under the conditions of a solvent-free or solvent-containing reaction system, and does not need to rely on the addition or selection of solvents in the system.

[0008] Specifically, the present invention provides the following technical solutions:

[0009] The invention provides a method for preparing phospholipid type polyunsaturated fatty acids, which are prepared by enzymatic reaction of raw materials comprising the following components: polyunsaturated fatty acid esters, polyunsaturated fatty acid salts, phospholipids and lipase, wherein the polyunsaturated fatty acids corresponding to the polyunsaturated fatty acid esters are of the same type as the polyunsaturated fatty acids corresponding to the polyunsaturated fatty acid salts.

[0010] The present invention finds that in order to ensure the fatty acid access rate of the solvent-free system, polyunsaturated fatty acid esters, polyunsaturated fatty acid salts and phospholipids in the above-mentioned reaction raw materials are essential substrates. Removing one of them or replacing it with other similar substrates will significantly reduce the fatty acid access rate.

[0011] In the above-mentioned raw material system, the type of polyunsaturated fatty acid in the polyunsaturated fatty acid salt is the same as the type of polyunsaturated fatty acid in the polyunsaturated fatty acid ester. The polyunsaturated fatty acid salt can be a single polyunsaturated fatty acid salt or a mixture of multiple polyunsaturated fatty acid salts. Similarly, the polyunsaturated fatty acid ester can also be a single polyunsaturated fatty acid ester or a mixture of multiple polyunsaturated fatty acid esters. If one of the polyunsaturated fatty acid ester and the polyunsaturated fatty acid salt is a mixture, the type of the polyunsaturated fatty acid with the highest content in the polyunsaturated fatty acid salt is the same as the polyunsaturated fatty acid with the highest content in the polyunsaturated fatty acid ester. For example: if the polyunsaturated fatty acid ester raw material contains 70% EPA ethyl ester, the polyunsaturated fatty acid salt is an EPA metal salt.

[0012] In the present invention, the polyunsaturated fatty acid esters include, but are not limited to, polyunsaturated fatty acid alkyl esters and polyunsaturated fatty acid glycerides.

[0013] As an embodiment, the raw materials for preparing the phospholipid type polyunsaturated fatty acids do not contain organic solvents.

[0014] As another embodiment, the raw material further comprises an organic solvent, and in the raw material, the mass volume ratio of the polyunsaturated fatty acid ester to the organic solvent is 1:(2-5) in g:mL.

[0015] For the above two embodiments, preferably, in the raw material, the mass ratio of the polyunsaturated fatty acid ester to the polyunsaturated fatty acid salt is (15-1500):1.

[0016] Further preferably, the polyunsaturated fatty acid ester is polyunsaturated fatty acid ethyl ester or polyunsaturated fatty acid glyceride. At this time, in the raw material, the mass ratio of the polyunsaturated fatty acid ethyl ester or polyunsaturated fatty acid glyceride to the polyunsaturated fatty acid salt is preferably (20-200):1.

[0017] Controlling the usage ratio of polyunsaturated fatty acid ester to polyunsaturated fatty acid salt within the above range is more conducive to improving the fatty acid accession rate.

[0018] In the present invention, the polyunsaturated fatty acid salt can be added to the reaction system alone, or the polyunsaturated fatty acid ester and the polyunsaturated fatty acid salt can be provided simultaneously by adding a fat raw material containing the polyunsaturated fatty acid ester and the polyunsaturated fatty acid salt.

[0019] Preferably, the lipase is a 1,3-specific lipase.

[0020] The present invention finds that, compared with non-directional lipase, the use of 1,3-specific lipase in the reaction system of the present invention can significantly increase the fatty acid accession rate.

[0021] Further preferably, in the raw materials, the mass ratio of the lipase to the raw materials other than the lipase is 10-30%.

[0022] Preferably, in the raw material, the mass ratio of phospholipids to polyunsaturated fatty acid esters is 1:(3-10).

[0023] In the preparation method of the present invention, the raw material also includes water, and the mass ratio of water to lipase in the raw material is 10-20%.

[0024] The polyunsaturated fatty acid described in the present invention can be one or more selected from ω-3 fatty acids, ω-6 fatty acids, docosahexaenoic acid, eicosapentaenoic acid, docosapentaenoic acid, arachidonic acid, octadecatrienoic acid, octadecadienoic acid or octadecatetraenoic acid.

[0025] The polyunsaturated fatty acid content in the polyunsaturated fatty acid ester used in the present invention is preferably controlled to be no less than 65%.

[0026] The polyunsaturated fatty acid salt used in the present invention is preferably a metal salt corresponding to the polyunsaturated fatty acid, including but not limited to sodium salt, potassium salt and the like.

[0027] The phospholipid used in the present invention is preferably glycerophospholipid. The phospholipid is preferably in a powdery state.

[0028] In the preparation method of the present invention, the reaction temperature of the enzymatic reaction is 45-65° C. The preferred reaction time is 4-24 hours.

[0029] Specifically, the present invention provides a method for preparing phospholipid-type polyunsaturated fatty acids in a solvent-free system, comprising the following steps:

[0030] (1) mixing polyunsaturated fatty acid ester, polyunsaturated fatty acid salt, phospholipid and water, wherein the mass ratio of polyunsaturated fatty acid ester to polyunsaturated fatty acid salt is (15-1500):1, and the mass ratio of phospholipid to polyunsaturated fatty acid ester is 1:(3-10);

[0031] (2) mixing the mixed material of step (1) with 1,3-specific lipase, wherein the mass ratio of lipase to reaction raw materials other than lipase is 10-30%, and the mass ratio of water to lipase is 10-20%, and performing enzymatic transesterification reaction at 45-65° C. for 4-24 hours;

[0032] (3) Separate the oil mixture to obtain phospholipid-type polyunsaturated fatty acids.

[0033] Preferably, in step (1), the mixing is performed at room temperature, more preferably by ultrasonic or stirring at room temperature.

[0034] In step (3), after the reaction is completed, the lipase is removed by centrifugation or filtration, and the oil mixture is collected.

[0035] The beneficial effects of the present invention are as follows: the preparation method of phospholipid polyunsaturated fatty acids provided by the present invention has a wide range of raw material selection, is independent of an organic solvent system, can achieve a good fatty acid access rate under both solvent-free and solvent-containing reaction system conditions, and can particularly achieve a significant increase in the fatty acid access rate in a solvent-free system, and significantly improve the content of polyunsaturated fatty acids in the prepared phospholipid polyunsaturated fatty acids. The method can be applied to a variety of reaction environments, wherein the preparation method of the solvent-free system also has the advantages of environmentally friendly production conditions and high safety, and is suitable for large-scale promotion and application. DETAILED DESCRIPTION

[0036] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0037] The raw material parameters used in the following examples are as follows: randomized lipase 435 is Novozym 435; lipase TL is Novozymes Lipozyme TLIM; immobilized lipase RMIM is Novozymes Lipozyme RM IM; powdered lecithin is Synbio (acetone insoluble matter 95%); EPA ethyl ester oil is obtained by extraction and transesterification of Nannochloropsis algae; DHA ethyl ester oil is obtained by extraction and transesterification of Schizochytrium.

[0038] Example 1

[0039] This embodiment provides a method for preparing phospholipid type polyunsaturated fatty acids, the steps are as follows:

[0040] (1) 18 g of EPA ethyl ester oil (area content 70.1%), 0.36 g of EPA sodium, 6 g of powdered phospholipids and 0.72 g of water were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0041] (2) Add 3.6 g of immobilized lipase RM IM to the substrate of step (1), place in a 65°C water bath, and stir at 300 rpm for 18 h;

[0042] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0043] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 28.0%.

[0044] Example 2

[0045] This embodiment provides a method for preparing phospholipid type polyunsaturated fatty acids, the steps are as follows:

[0046] (1) 18 g of EPA ethyl ester oil (area content 70.1%), 0.36 g of EPA sodium, 6 g of powdered phospholipids and 0.72 g of water were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0047] (2) Add 3.6 g of lipase TL to the substrate of step (1), place in a 65°C water bath, and stir at 300 rpm for 18 h;

[0048] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0049] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 18.5%.

[0050] Example 3

[0051] This embodiment provides a method for preparing phospholipid type polyunsaturated fatty acids, the steps are as follows:

[0052] (1) 18 g of EPA ethyl ester oil (EPA content 80%), 0.60 g of EPA sodium, 4.5 g of powdered phospholipids and 0.72 g of water were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0053] (2) Add 3.6 g of immobilized lipase RM IM to the substrate in step (1), place in a 65° C. water bath, and stir at 300 rpm for 18 h.

[0054] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0055] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 28.2%.

[0056] Example 4

[0057] This embodiment provides a method for preparing phospholipid type polyunsaturated fatty acids, the steps are as follows:

[0058] (1) 18 g of EPA ethyl ester oil (area content 70.1%), 0.18 g of EPA sodium, 3.6 g of powdered phospholipids and 0.36 g of water were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0059] (2) Add 3.6 g of immobilized lipase RM IM to the substrate of step (1), place in a 65°C water bath, and stir at 300 rpm for 18 h;

[0060] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0061] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 27.4%.

[0062] Example 5

[0063] This embodiment provides a method for preparing phospholipid type polyunsaturated fatty acids, the steps are as follows:

[0064] (1) 18 g of DHA ethyl ester oil (area content 71%), 0.58 g of DHA potassium, 6 g of powdered phospholipids and 0.72 g of water were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0065] (2) Add 3.6 g of immobilized lipase RM IM to the substrate of step (1), place in a 65°C water bath, and stir at 300 rpm for 18 h;

[0066] (3) After the reaction is completed, the mixture obtained by the reaction is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0067] The phospholipids in the oil mixture were separated, methylated and then subjected to gas chromatography detection, and the area content of DHA in the phospholipids was found to be 25.6%.

[0068] Example 6

[0069] This embodiment provides a method for preparing phospholipid type polyunsaturated fatty acids, the steps are as follows:

[0070] (1) Mixing a mixture of fat (containing 18 g of EPA ethyl ester oil (area content 70.1%), 0.09 g of EPA sodium and 0.72 g of water) with 6 g of powdered phospholipids, and dispersing them by ultrasonication for 5 min to obtain a substrate;

[0071] (2) Add 3.6 g of immobilized lipase RM IM to the substrate of step (1), place in a 65°C water bath, and stir at 300 rpm for 18 h;

[0072] (3) After the reaction is completed, the mixture obtained by the reaction is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0073] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 23.5%.

[0074] Example 7

[0075] This embodiment provides a method for preparing phospholipid type polyunsaturated fatty acids, the steps are as follows:

[0076] (1) 25.2 g of EPA glyceride (area content 70.1%), 0.36 g of EPA sodium, 0.72 g of water and 6 g of powdered phospholipid were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0077] (2) Add 3.6 g of immobilized lipase RM IM to the substrate of step (1), place in a 65°C water bath, and stir at 300 rpm for 18 h;

[0078] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0079] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 7.2%.

[0080] Example 8

[0081] This embodiment provides a method for preparing phospholipid type polyunsaturated fatty acids, the steps are as follows:

[0082] (1) 18 g of EPA ethyl ester oil (area content 70.1%), 0.36 g of EPA sodium, 6 g of powdered phospholipids and 0.72 g of water were mixed, 50 ml of n-hexane was added, and the mixture was dispersed by ultrasonication for 5 min to obtain a substrate;

[0083] (2) Add 3.6 g of immobilized lipase RM IM to the substrate of step (1), place in a 65°C water bath, and stir at 300 rpm for 18 h;

[0084] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0085] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 27.3%.

[0086] Comparative Example 1

[0087] This comparative example provides a method for preparing phospholipid-type polyunsaturated fatty acids, and the steps are as follows:

[0088] (1) 18 g of EPA ethyl ester oil (area content 70.1%), 0.72 g of water and 6 g of powdered phospholipid were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0089] (2) Add 3.6 g of immobilized lipase RM IM to the substrate of step (1), place in a 65°C water bath, and stir at 300 rpm for 18 h;

[0090] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0091] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 10.3%.

[0092] Comparative Example 2

[0093] This comparative example provides a method for preparing phospholipid-type polyunsaturated fatty acids, and the steps are as follows:

[0094] (1) 18 g of EPA fatty acid, 0.36 g of EPA sodium, 6 g of powdered phospholipids and 0.72 g of water were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0095] (2) adding 3.6 g of immobilized lipase RM IM to the substrate in step (1), placing in a 65° C. water bath, and stirring at 300 rpm for 18 h;

[0096] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0097] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 5.0%.

[0098] Comparative Example 3

[0099] This comparative example provides a method for preparing phospholipid-type polyunsaturated fatty acids, and the steps are as follows:

[0100] (1) 18 g of EPA ethyl ester oil (area content 70.1%), 0.36 g of EPA sodium, 0.72 g of water and 6 g of powdered phospholipid were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0101] (2) adding 3.6 g of randomized lipase 435 to the substrate of step (1), placing in a 65° C. water bath, and stirring at 300 rpm for 18 h;

[0102] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0103] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 6.8%.

[0104] Comparative Example 4

[0105] This comparative example provides a method for preparing phospholipid-type polyunsaturated fatty acids, and the steps are as follows:

[0106] (1) 17.5 g of DHA ethyl ester (DHA content of 71%) and 5 g of soybean lecithin raw material were mixed, and 40 ml of n-hexane was added to obtain a fat mixture;

[0107] (2) preheating the oil mixture obtained in step (1) to 52° C.;

[0108] (3) adding 0.604 g DHA potassium salt, 0.06 g water, and 3 g immobilized lipase RM IM to the reaction mixture obtained in step (2), and performing ultrasonic dispersion; reacting at a temperature of 55° C. for 8 hours to obtain a fat composition;

[0109] The phospholipids in the oil mixture were separated, methylated and then subjected to gas chromatography detection, and the area content of DHA in the phospholipids was 7.4%.

[0110] Comparative Example 5

[0111] This comparative example provides a method for preparing phospholipid-type polyunsaturated fatty acids, and the steps are as follows:

[0112] (1) 18 g of EPA sodium, 6 g of powdered phospholipids, 50 mL of n-hexane and 0.72 g of water were mixed and dispersed by ultrasonication for 5 min to obtain a substrate;

[0113] (2) Add 3.6 g of immobilized lipase RM IM to the substrate of step (1), place in a 65°C water bath, and stir at 300 rpm for 18 h;

[0114] (3) After the reaction is completed, the reaction mixture is centrifuged at 6000 rpm for 5 min to remove the immobilized enzyme in the lower layer and collect the oil mixture.

[0115] The phospholipids in the oil mixture were separated, methylated and then detected by gas chromatography, and the area content of EPA in the phospholipids was 3.0%.

[0116] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing phospholipid-type polyunsaturated fatty acids, characterized in that: The invention is prepared by enzymatic reaction of raw materials including the following components: polyunsaturated fatty acid ester, polyunsaturated fatty acid salt, phospholipid and lipase, Wherein, the polyunsaturated fatty acid corresponding to the polyunsaturated fatty acid ester is of the same type as the polyunsaturated fatty acid corresponding to the polyunsaturated fatty acid salt; The raw material does not contain an organic solvent; The polyunsaturated fatty acid ester is a polyunsaturated fatty acid ethyl ester, and the polyunsaturated fatty acid salt is a sodium salt or a potassium salt; In the raw materials, the mass ratio of the polyunsaturated fatty acid ethyl ester to the polyunsaturated fatty acid salt is (20-200):1; The lipase is a 1,3-specific lipase.

2. The method for preparing phospholipid type polyunsaturated fatty acids according to claim 1, characterized in that: In the raw materials, the mass ratio of the lipase to the raw materials other than the lipase is 10-30%.

3. The method for preparing phospholipid type polyunsaturated fatty acids according to claim 1, characterized in that: The mass ratio of the phospholipid to the polyunsaturated fatty acid ester is 1:(3-10).

4. The method for preparing phospholipid-type polyunsaturated fatty acids according to any one of claims 1 to 3, characterized in that: The raw materials also include water, and the mass ratio of water to lipase is 10-20%.

5. The method for preparing phospholipid-type polyunsaturated fatty acids according to any one of claims 1 to 3, characterized in that: The polyunsaturated fatty acids are ω-3 fatty acids and / or ω-6 fatty acids.

6. The method for preparing phospholipid type polyunsaturated fatty acids according to claim 5, characterized in that: The ω-3 fatty acid is one or more selected from docosahexaenoic acid, eicosapentaenoic acid, docosapentaenoic acid, octadecatrienoic acid, and octadecatetraenoic acid.

7. The method for preparing phospholipid type polyunsaturated fatty acids according to claim 5, characterized in that: The ω-6 fatty acid is one or two selected from arachidonic acid and octadecadienoic acid.

8. The method for preparing phospholipid-type polyunsaturated fatty acids according to any one of claims 1 to 3, characterized in that: The temperature of the reaction is 45-65°C.