JPH0544952B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a new method for producing egg yolk lecithin with a reduced content of phosphatidylethanolamine (in the present invention abbreviated as PE) and/or substantially free of impurities. be. [Prior Art] Conventionally, a lipid fraction derived from egg yolk containing phospholipids such as phosphatidylcholine (in the present invention, abbreviated as PC), so-called egg yolk lecithin, has been developed due to the surfactant action of the phospholipid contained therein. It is widely used in the fields of cosmetics and pharmaceuticals as an emulsifier, a liposome forming agent as a drug carrier, etc., taking advantage of its various properties such as osmotic action. By the way, PC is structurally a cylindrical molecule with a well-balanced size of hydrophobic and hydrophilic groups, so when egg yolk lecithin with a high PC content is used as a liposome forming agent, it can form liposomes with a stable lipid bilayer. It has the advantage of being able to form In this case, if egg yolk lecithin, which has a high PC content and a low PE content, is used as a raw material, a liposome with higher structural stability, that is, a strong yet flexible membrane can be produced. like this,
Egg yolk lecithin with a high PC content and a low PE content also has the advantage of stabilizing various physical properties of the final product when used as a cosmetic raw material. Therefore, if it is possible to produce egg yolk lecithin with a reduced PE content and a relatively increased PC content, the obtained egg yolk lecithin can be of great industrial benefit. [Problems to be solved by the invention] Egg yolk lecithin (lipid fraction) obtained by extraction from egg yolk by a conventional method mainly consists of phospholipids such as PC and PE, and neutral lipids such as triglyceride and cholesterol. It is something. Various methods for fractionating phospholipids from egg yolk lecithin have been known, for example, as described in Japanese Patent Application Laid-Open No. 152392-1982.
According to the publication, a solution obtained by dissolving a lipid fraction in a non-polar or weakly polar solvent is brought into contact with a resin that preferentially adsorbs phospholipids to adsorb the phospholipids, and then the solution is dissolved in a polar solvent. A method is disclosed in which adsorbed phospholipids are eluted using. According to this method, phospholipid fractions with different PE/PC ratios can be obtained by collecting the eluate in fractions, but the fractions with high PC content and low PE content are used as the lipid fraction raw material to be processed. It can only be obtained in an extremely low proportion (approximately 10%), and in an extremely large amount (approximately 200 times the amount (v/v)) of this raw material.
It is difficult to economically fractionate phospholipids with a high PC content and a low PE content on an industrial scale by this method due to the necessity of the resin of (v))). Furthermore, various methods have been attempted to enrich the PC component of egg yolk lecithin. For example, a solvent fractionation method is known in which PE is precipitated by adding water to a solution of egg yolk lecithin in ethanol. However, this method has the disadvantage that increasing the PC content significantly reduces the yield of the final product. Alternatively, a method using an adsorbent such as silica gel or alumina is also known. However, although this method has a high separation ability for PC and PE, the yield of the final product is low, and it requires a large amount of adsorbent, making it difficult to implement on an industrial scale. Another known method is to form a metal salt complex with Cd, Ca, Mg, Zn, etc. and utilize its solubility. However, this method has the disadvantage that residual metals cannot be avoided in the final product obtained. Under these circumstances, it is an object of the present invention to provide a method for producing egg yolk lecithin with a reduced PE content and a relatively increased PC content in a high yield on an industrial scale. [Means for Solving the Problems] As a result of extensive research in accordance with the above-mentioned objective, the present inventors have found that after dissolving egg yolk lecithin in a polar solvent or a mixture of a polar solvent and a non-polar solvent, ions The present invention was completed by discovering that this ion exchange resin selectively and efficiently adsorbs and removes substantially only PE among lipid components when brought into contact with an exchange resin. Therefore, in one aspect, the present invention provides the steps of dissolving egg yolk lecithin in a polar solvent or a mixture of a polar solvent and a non-polar solvent, contacting the resulting solution with an ion exchange resin, and then distilling off the solvent from the solution. The present invention provides a method for producing egg yolk lecithin with reduced PE content. The present inventors investigated the egg yolk lecithin thus obtained from the viewpoint of the residual content of impurities, mainly inorganic salts and free amino acids derived from raw materials, and surprisingly found that these impurities were virtually undetectable. I found out. Therefore, in another aspect of the present invention, the method of the present invention is carried out using crude egg yolk lecithin or semi-purified egg yolk lecithin containing inorganic salts and free amino acids as main impurities as a starting material, and the final product has a PE content. The object of the present invention is to provide a method for producing egg yolk lecithin with reduced and substantially free of said impurities. The inventors conducted further research and found that the effect of removing PE and impurities is mainly proportional to the amount of ion exchange resin used, and that PE is removed after most of the impurities have been practically removed. . Therefore, the present invention has another aspect, in which the method of the present invention is carried out using crude egg yolk lecithin or semi-purified egg yolk lecithin as a starting material,
It can be said that the present invention provides a method for producing egg yolk lecithin that is substantially free of impurities as a final product. The present invention will be explained in detail below. Egg yolk lecithin, which is a raw material to which the method of the present invention is applied, is a lipid fraction containing phospholipids mainly containing PC, which is obtained by solvent extraction from egg yolk by a conventional method using, for example, ethanol, dichloromethane, hexane, ether, etc. be. This lipid fraction contains inorganic salts (e.g. salts of sodium, potassium, calcium, magnesium, iron, etc.) and free amino acids as main impurities (crude egg yolk lecithin);
Alternatively, crude egg yolk lecithin is subjected to diatomaceous earth filtration, membrane filtering, etc. to reduce the amount of impurities (semi-purified egg yolk lecithin), or crude egg yolk lecithin or semi-purified egg yolk lecithin is treated with acetone etc. by a conventional method. Contains a product with increased phospholipid content (high phospholipid egg yolk lecithin). The solvent for the egg yolk lecithin used in the method of the invention is either a polar solvent, such as methanol, ethanol, acetone, dichloromethane, water, etc., or a combination of these polar solvents and a non-polar solvent, such as n-pentane, n-hexane, n- heptane,
It is a mixture with chloroform, ethyl acetate, ether, benzene, etc. As is clear from the results of the test examples described below, it is difficult to obtain the effect of removing PE and impurities using a nonpolar solvent alone. Although the mixing ratio of the polar solvent and the non-polar solvent in the mixture is not particularly limited, it is generally preferable that the ratio of the polar solvent is larger. The concentration of egg yolk lecithin in the solvent, i.e. the concentration of egg yolk lecithin in the resulting solution is 0.5-20%.
(v/v) is preferable. This is because if the amount is less than 0.5%, the amount of solvent is too large and is not economical, and if it exceeds 20%, the viscosity increases and the subsequent contact operation with the ion exchange resin becomes difficult. The ion exchange resin used in the method of the present invention is not particularly limited, but commercially available strongly acidic or weakly acidic cation exchange resins, or strongly basic or weakly basic anion exchange resins are preferably used. Examples of strong acidic resins include Amberlite.
IR120B, 200C (both manufactured by Rohm &Hass); Dowex 50W, MSC-1 (both manufactured by Dow
Chemical); DuoLite C-20, C-25D (both manufactured by Diamond Shamrock); Lewatit
S-100, SP-120 (both manufactured by Bayer), etc., and weakly acidic resins such as Amberlite
IRC50, IRC84; Dowex CCR-2; DuoLite
CC-4; Lewatit CNP-80, etc. can be mentioned. As a strong basic resin, for example, Amberlite
IRA400, IRA900; Dowex 1, MSA-1; DuoLite A-101D; Lewatit M-500, MP-500, and weakly basic resins such as Amberlite IRA68,
Examples include IRA45; Lewatit MP-62. These resins may be used alone, or two or more of them may be used in a mixed form or sequentially in any proportion. Specifically, for example, one type of acidic resin and one type of basic resin are mixed in a ratio of 1:3 to 1:3.
They are used by mixing at a ratio of 2:1. In addition, in order to increase the adsorption efficiency during use, it is preferable to prepare the acidic resin to be H type and the basic resin to be OH type. The amount of ion exchange resin used may vary depending on the amount of PE and impurities contained in the raw egg yolk lecithin or the type of resin used, but generally it is based on the amount of PE contained in the raw egg yolk lecithin. It is recommended to use at least 3 times the normal capacity on a capacity basis. This is because if the amount used is less than 3 times, it is difficult to obtain a sufficient PE and impurity removal effect. Preferably, in the raw material
The amount may be appropriately selected within the range of 4.0 to 40 times depending on the amount of PE and impurities. If within this range, PE
The content is 2%, which is considered to be an acceptable residual amount on an industrial scale.
It is possible to reduce the amount to less than a trace amount, and moreover, it can be substantially free of impurities.
Therefore, it is not economical to use too much resin. In addition, since PE is removed after virtually all impurities have been removed, the amount of ion exchange resin used is controlled when carrying out the method of the present invention using crude egg yolk lecithin or semi-purified egg yolk lecithin as a starting material. In this way, it is possible to produce egg yolk lecithin that is substantially free of impurities and has almost the same PE content. In this case, the amount of ion exchange resin used is usually 0.2 times or more of the crude egg yolk lecithin or semi-purified egg yolk lecithin raw material on a volume basis. This is because if the amount used is less than 0.2 times, it is difficult to obtain a sufficient impurity removal effect. Preferably, the amount may be appropriately selected within the range of 0.3 to 3.0 times depending on the amount of impurities in the raw material. If the amount is too high, PE will be removed. The egg yolk lecithin solution and the ion exchange resin can be brought into contact by flowing the solution through a column packed with a predetermined amount of resin in a conventional manner, or by adding a predetermined amount of resin into the solution and suspending it under stirring. All you have to do is implement it. This contact is preferably carried out at a temperature lower than the boiling point of the solvent in order to prevent evaporation of the solvent. According to the method of the present invention, after selectively adsorbing PE and/or impurities on the ion exchange resin through the above-mentioned contact, the solution passed through the column can be directly adsorbed, or the solution that has been brought into contact with the column can be directly adsorbed on the ion exchange resin. After removing, for example, by filtration, the solvent used is distilled off from the solution, for example, under reduced pressure. According to the method of the present invention, the PE content in egg yolk lecithin as a raw material is extremely effectively reduced.
Egg yolk lecithin with a relatively increased PC content and substantially free of impurities can be produced. Moreover, as is clear from the results of the test examples described below, even if the amount of ion exchange resin used is about three times the volume (v/v) of the PE content in raw egg yolk lecithin, the PE content can be reduced to about half. This means that the amount of resin used can be extremely small, and moreover, the resin is free of impurities and virtually no lipid components.
Since only PE is selectively adsorbed and removed, the final product can be produced with high yield, and therefore egg yolk lecithin that is virtually free of impurities, has a high PC content, and has a low or almost no PE content can be produced on an industrial scale. It can be manufactured in It goes without saying that the method of the present invention can be carried out more efficiently by repeated implementation. In addition, according to the method of the present invention, by appropriately controlling the amount of ion exchange resin used, PE
Egg yolk lecithin which is substantially free of impurities and whose content remains approximately the same can be produced very easily on an industrial scale. [Effects of the Invention] In one embodiment, the egg yolk lecithin obtained by the method of the present invention has a PE content that is extremely effectively reduced to almost no content, and a PC content that is relatively increased. Since this egg yolk lecithin does not contain any upper impurities, it is expected that its use will be expanded in various fields, especially in the fields of pharmaceuticals and cosmetics. In another embodiment, the egg yolk lecithin obtained by the method of the present invention is an egg yolk lecithin that is substantially free of impurities, with the PE content substantially maintained, that is, the phospholipid composition maintained. Therefore, it is expected that it will be used as a purified monophospholipid material in various fields, for example, as an emulsifier. In particular, it has been difficult to virtually completely remove impurities such as inorganic salts, free amino acids, and polypeptides from crude egg yolk lecithin, and its solubility in ordinary organic solvents is therefore poor, limiting its range of use. However, the method of the present invention allows egg yolk lecithin to be obtained which is substantially free of such impurities and has further improved solubility, so that its use can be further expanded in various fields. . The effects of the present invention will be further explained below using the results of test examples. In the present invention, all percentages are by weight unless otherwise specified. Furthermore, both egg yolk lecithin and PE have a specific gravity of approximately 1. Test Example 1 This test example shows how the PE and impurity removal effectiveness of the method of the present invention varies depending on the type of solvent used. Prepared egg yolk lecithin (PC: 58.0%, PE:
10.0%) 20g each of absolute ethanol, n-hexane, chloroform, ethyl acetate, 95% ethanol, chloroform-methanol-water (10:10:
1) Dissolve each in 200ml of each, and add the resulting solution to Amberlite IR120B in advance.
(H type) and Amberlite IRA400 (OH type) 10 each
After flowing the mixture in a ratio of 1.0 ml to a column packed according to a conventional method, the solvent used in each solution was completely distilled off under reduced pressure to obtain a final egg yolk lecithin sample. Next, for each sample, the remaining amount of PE was determined using Iyatroscan TH-10, impurities were determined by atomic absorption spectrometry for metal ions, and amino acid analysis was performed for the amount of free amino acids. The results are shown in Table 1 below.

[Table] From the above results, it can be seen that using a polar solvent or a mixture of a polar solvent and a non-polar solvent can very effectively reduce the PE and impurity content in the raw egg yolk lecithin, but on the other hand, only a non-polar solvent It can be seen that it is difficult to obtain the effect of removing PE and impurities when using . Test Example 2 This test example shows that in the method of the present invention, PE can be effectively removed even when the amount of ion exchange resin used is extremely small. Prepared egg yolk lecithin (PC: 78.2%, PE:
20.0%) each (PE content: 4.0 g) was dissolved in 180 ml of 95% ethanol, and each of the resulting solutions was mixed with Dowex 50W (H type) in advance.
2ml, 4ml of equal amounts of mixture with Dowex1 (OH type),
6ml, 8ml, 10ml, 12ml, 14ml, 16ml and 20ml
After flowing through each column packed according to a conventional method, the solvent was completely distilled off from each solution under reduced pressure to obtain a final egg yolk lecithin sample. The remaining PE content of each sample was then examined using an Iatroscan TH10. The results are shown in Table 2 below.

[Table] From the above results, the amount of resin used is 3 times the volume (v/v) of the PE content contained in the raw egg yolk lecithin.
It can be seen that the PE content can be reduced to about half in a matter of seconds, and therefore, in the method of the present invention, the amount of resin used can be extremely small. Test Example 3 This test example shows how the impurity removal effect differs depending on the type of solvent used when only impurities are removed by controlling the amount of ion exchange resin used in the method of the present invention. . Prepared egg yolk lecithin (PC: 79.2%, PE:
20.0%, metal ions: 1100mg%, free amino acids:
800mg%) 20g each of ether, n-hexane, 95
% ethanol, chloroform-methanol (2:
1), n-hexane-acetone (2::1) 200 each
ml of Amberlite IR120B (H type) and 2 ml of Amberlite IR120B (H type) and
After adding 3 ml of Amberlite IR400 (OH type) and stirring for 30 minutes, the ion exchange resin was removed, and the solvent used from each solution was completely distilled off under reduced pressure to obtain the final egg yolk lecithin sample. . Next, a 5 w/v% emulsion was prepared for each sample, and the electrical conductivity was measured. The results are shown in Table 3 below.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Prepared egg yolk lecithin (PC: 56.9%, PE: 9.6
%, cholesterol: 14.9%, triglyceride: 18.6%, metal ion: 960mg%, free amino acid: 680mg%, electrical conductivity: 690μS/cm) 500g
Dissolve in 95% ethanol 4.5 and mix the resulting solution in advance with 500 ml of Amberlite IR120B (H type).
A mixture of 1,000 ml of Amberlite IRA400 (OH type) was poured into a column packed in a conventional manner, and the solvent used was completely distilled off from this solution under reduced pressure to reduce the PE content to 1.0%. 450g of egg yolk lecithin was obtained. The ratio of components other than PE in this product was PC: 62.0%, cholesterol: 15.7%, triglyceride: 19.9%, metal ion: 72 mg%, free amino acid: 59 mg%, and the electrical conductivity was 28 μS/cm. Example 2 Prepared egg yolk lecithin (PC: 79.6%, PE:
18.0%, cholesterol 1.2%, metal ions:
1100mg%, free amino acid: 600mg%, electrical conductivity: 720μS/cm) 200g was dissolved in chloroform-methanol-water (10:10:1) 2, and the resulting solution was preliminarily prepared using Dowex 50W (H type). 200ml and
A mixture of 400 ml of Dowex 1 (OH type) was poured into a column packed in a conventional manner, and the solvent used from this solution was completely distilled off under reduced pressure.
80 g of egg yolk lecithin whose content was reduced to 1.0% was obtained. The ratio of ingredients other than PE in this product is PC: 96.1
%, cholesterol: 1.4%, metal ions: 40mg
%, free amino acid: 20mg%, electrical conductivity is
It was 12μS/cm. Example 3 Prepared egg yolk lecithin (PC: 29.6%, PE: 3.3
%, cholesterol 4.3%, triglycerides
62.3%, metal ions: 520mg%, free amino acids:
210mg%, electrical conductivity: 230μS/cm) 500g (PE
Content: 16.5 g) was dissolved in 99.5% ethanol 4.5 g, and the resulting solution was preliminarily mixed with Lawatit S-100.
A mixture of 25 ml of (H type) and 25 ml of Lawatit M-500 (OH type) was poured into a column packed in a conventional manner, and the solution used was completely distilled off from this solution under reduced pressure. 490 g of egg yolk lecithin with PE content reduced to 1.6% was obtained. The ratio of ingredients other than PE in this product is PC: 30.2%, cholesterol: 4.5%,
Triglyceride: 63.1%, Metal ion: 73mg
%, free amino acid: 26mg%, electrical conductivity is
It was 32μS/cm. In addition, in Examples 1 to 3 above, even when the egg yolk lecithin solution and the ion exchange resin were simply brought into contact with stirring without using a column, the PE and impurity contents were almost the same in all Examples. A reduced egg yolk lecithin was obtained. Example 4 Prepared egg yolk lecithin (PC: 78.0%, PE:
18.3%, cholesterol: 2.0%, triglyceride: 0%, metal ion: 1000mg%, free amino acid: 700mg%, electrical conductivity: 730μS/cm) was dissolved in hexane-ethanol (80:20),
Add 60ml of Amberlite IR 120B (H type) to the obtained solution.
and Amberlite IRA 400, OH type) 120ml
Stir and mix for 30 minutes. Next, after separating the ion exchange resin from this solution, the solvent used was completely distilled off under reduced pressure, and then treated with acetone to obtain 76 g of egg yolk lecithin with a PE content of 0%. The proportions of components other than PE in this product were PC: 96.8%, cholesterol: 1.5%, metal ions: 50 mg%, free amino acids: 120 mg%, and the electrical conductivity was 5.3 μS/cm. Example 5 Egg yolk lecithin (PC: 80.5%, PE: 17.3%,
Cholesterol: 0.5%, triglyceride: 0.1
%, metal ions: 430mg%, free amino acids: 180mg
%, electrical conductivity: 120 μS/cm) was dissolved in chloroform-methanol-water (10:10:1), and DuoLite C-20 (H type) 1000 was added to the resulting solution.
ml and DuoLite A-l0lD (OH type) 2000ml
Stir and mix for 30 minutes. Next, after separating the ion exchange resin from this solution, the solvent used was completely distilled off under reduced pressure, and then treated with acetone to reduce the PE content to 2%.
1.4 kg of egg yolk lecithin was obtained. The ratio of components other than PE in this egg yolk lecithin is PC: 94.2
%, cholesterol: 0.8%, triglyceride: 0.1%, metal ion: 48 mg%, free amino acid: 16 mg%, and the electrical conductivity was 7.3 μS/cm. Examples 6 to 8 In each example, the required number of solutions were prepared by dissolving the crude egg yolk lecithin shown in Table 4 below in the solvent shown in the same table, and each solution was treated with the ion exchange agent shown in the same table. A mixture of resins was added in different amounts, mixed with stirring for 30 minutes at room temperature (20°C), and then the used resin was separated, and the solvent used was then completely distilled off under reduced pressure. Egg yolk lecithin samples according to quantity were obtained. Next, the amount of PE and impurity remaining in each sample obtained in each example was measured using the method used in Test Example 1. The results are shown in graphs for each example (see Figures 1 to 3).

[Table] Examples 9 to 11 below are examples in which only impurities in raw egg yolk lecithin are removed by controlling the amount of ion exchange resin used within a predetermined amount in the method of the present invention. Example 9 Prepared egg yolk lecithin (PC: 51.7%, PE:
10.2%, neutral lipids: 37.2%, free amino acids: 660
mg%, metal ion: 1090mg%, electrical conductivity:
566μS/cm) 1200g in water-saturated dichloromethane 12
Amberlite IR in the resulting solution
120B (H type) 200ml and Amberlite IRA 400 (OH
After stirring and mixing for 30 minutes, the ion exchange resin used was separated, the solvent used was completely distilled off under reduced pressure, and purified egg yolk lecithin was added.
Obtained 1170g. The component ratios of this purified egg yolk lecithin are: PC: 52.0%, PE: 10.0%, neutral lipid: 37.3
%, free amino acids: 37mg%, metal ions: 180mg
%, and the electrical conductivity was 6.4 μS/cm. Next, the solubility of the thus obtained purified egg yolk lecithin in organic solvents was examined in comparison with the raw material. The results are shown in Table 5 below. The solubility was measured by preparing a 10 w/v% solution using each solvent.

[Table] Example 10 Prepared egg yolk lecithin (PC: 79.9%, PE:
16.6%, neutral lipids: 1.7%, free amino acids: 570mg
%, Metal ion: 1100mg%, Electrical conductivity:
750 μS/cm) was dissolved in 3 n-hexane-acetone (2:1), and the resulting solution was
Dowex 50W (H type) 250ml and Dowex (OH type)
After stirring and mixing for 15 minutes, the ion exchange resin used was separated, and the solvent used was completely distilled off under reduced pressure.
I got g. The component ratio of this purified egg yolk lecithin is
PC: 79.8%, PE: 16.4%, neutral lipid: 1.8%, free amino acid: 10 mg%, metal ion: 127 mg%, and the electrical conductivity was 29 μS/cm. Next, the solubility of the thus obtained purified lecithin in organic solvents was examined in comparison with the raw material according to the method of Example 9 above. The results are shown in Table 6 below.

[Table] Example 11 Prepared egg yolk lecithin (PC: 77.0%, PE:
17.5%, neutral lipids: 4.6%, free amino acids: 274mg
%, Metal ion: 346mg%, Electrical conductivity:
250μS/cm) was dissolved in chloroform-methanol-water (10:5:1), and 50ml of DuoLite C-20 (H type) and DuoLite were added to the resulting solution.
After adding 150 ml of A-101D (OH type) and stirring and mixing for 30 minutes, the ion exchange resin used was separated, and the solvent used was then completely distilled off under reduced pressure to obtain 980 g of purified egg yolk lecithin. The component ratios of this purified egg yolk lecithin were PC: 77.6%, PE: 16.5%, neutral lipids: 4.8%, free amino acids: 45 mg%, metal ions: 190 mg%, and the electrical conductivity was 28 μS/cm. Next, the solubility of the thus obtained purified lecithin in organic solvents was examined in comparison with the raw material according to the method of Example 9 above. The results are shown in Table 7 below.

【table】 [Brief explanation of the drawing]

1 to 3 are graphs showing the results of the tests conducted in Examples 6 to 8, respectively.

Claims (1)

[Claims] 1. Dissolving egg yolk lecithin in a polar solvent or a mixture of a polar solvent and a non-polar solvent, contacting the resulting solution with an ion exchange resin, and then distilling off the solvent from the solution. Characteristic method for producing egg yolk lecithin with reduced PE (phosphatidylethanolamine) content. 2. Egg yolk lecithin as a starting material is a crude egg yolk lecithin or its semi-fertilized egg yolk lecithin containing inorganic salts and free amino acids as main impurities, and the product obtained after solvent distillation has a reduced PE content and substantially contains the impurities. The manufacturing method according to claim 1, which is egg yolk lecithin-free. 3. The production method according to claim 1, wherein the starting material, egg yolk lecithin, contains phospholipids and neutral lipids as main components. 4. The production method according to claim 1, wherein the starting material egg yolk lecithin is high phospholipid egg yolk lecithin. 5. The production method according to any one of claims 2 to 4, wherein the ion exchange resin is used at least three times the PE content in the egg yolk lecithin raw material on a volume basis. 6. The manufacturing method according to claim 5, wherein the ion exchange resin is used in a range of 4.0 to 40 times on a volume basis. 7 the polar solvent is selected from methanol, ethanol, acetone, dichloromethane and water;
A manufacturing method according to any one of claims 1 to 6. 8 The concentration of egg yolk lecithin in the solvent is 0.5-20%
(v/v), the manufacturing method according to any one of claims 1 to 7. 9 After dissolving crude egg yolk lecithin or semi-purified egg yolk lecithin containing inorganic salts and free amino acids as main impurities in a polar solvent or a mixture of a polar solvent and a non-polar solvent, and contacting the resulting solution with an ion exchange resin. A method for producing egg yolk lecithin substantially free of impurities, which comprises distilling off the medium from this solution. 10. The production method according to claim 9, wherein the ion exchange resin is used at least 0.2 times the volume of crude egg yolk lecithin or its semi-purified egg yolk lecithin raw material. 11. The manufacturing method according to claim 10, wherein the ion exchange resin is used in a range of 0.3 to 3.0 times on a capacity basis.