JPH0560839B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a method for extracting and producing lecithin from egg yolk. In particular, the present invention relates to a method for hygienically obtaining high-yield lecithin of high purity that can be used in pharmaceuticals and the like. Lecithin is used in the food and pharmaceutical fields due to its surfactant properties, and egg yolk lecithin is used in artificial blood, lipoemulsions, and vitamin E due to its emulsification retention and safety.
It is being used and developed in the pharmaceutical field. Therefore, establishing a method for producing egg yolk lecithin that is inexpensive and highly safe will greatly contribute to these industries. ``Prior art'' There are several known methods for producing egg yolk lecithin.
-6259 etc. Japanese Patent Publication No. 56-47915 is a method for separating lecithin and neutral lipids by extracting and separating lecithin, neutral lipids, and some water from raw egg yolk with dimethyl ether, removing the solvent, and adjusting the water content in the extracted oil. . In this method, lecithin is recovered together with water, so it must be dehydrated and dried afterwards, but it is not possible to raise the temperature of the product because it affects the quality of the lecithin, forcing expensive freeze-drying. It has drawbacks such as: Japanese Patent Publication No. 46-42186 states that after adding half to twice the amount of monohydric alcohol and a small amount of acid to egg yolk and stirring to bring the pH to about 3 to 6, add water that is twice to four times the amount of egg yolk and centrifuge it. It is characterized by dividing the triglyceride/sterin layer, which does not contain phospholipids, into a phospholipid layer and a protein layer from the top layer. This is done by denaturing protein with acid or alcohol to make it easier to separate lipids and proteins, and as is known from the degumming (removal of phospholipid content) of vegetable oils, phospholipids are Taking advantage of the fact that neutral lipids such as triglycerides do not dissolve in the presence of water, water is added to separate them from triglycerides, and further from proteins based on the difference in specific gravity. Japanese Patent Publication No. 37-6259 discloses a method for obtaining extracted egg yolk oil by soaking and filtering egg yolks that have been semi-dried to a moisture content of 37 to 29% with acid-added absolute alcohol, and then using an oil-fat solvent. This method requires pretreatment steps such as semi-drying, and the steps such as acid removal and filtration are complicated, and the resulting egg yolk oil contains neutral lipids, unlike the high-purity lecithin expected by the present inventors. It is something that Lecithin is usually insoluble in acetone, but neutral lipids are soluble in acetone, so there are methods to purify lecithin that take advantage of this property, but these methods do not easily remove acetone. There are disadvantages such as residual mesityl oxide with a characteristic odor. As described above, the methods known so far are high in cost, have complicated steps, and contain components with specific odor, so there is still room for improvement. "Problems to be Solved by the Invention" The purpose of the present invention is to extract lipids containing lecithin from egg yolks and to produce lecithin from the lipids using safe solvents commonly used in food production. The object of the present invention is to provide a method capable of obtaining hygienically safe and highly purified lecithin at a high yield. Egg yolk is about 50% water, about 15% protein, and about 35% fat.
%, and is a system in which neutral lipids are emulsified with lecithin, cholesterol, and protein.
Since this emulsion is very stable, even if an extraction operation is performed simply with a non-polar solvent such as hexane, the extraction rate is very low, and in particular, phospholipids, which are polar lipids, are difficult to extract. The present inventors focused on the fact that emulsification is an effect of lecithin, cholesterol, and protein, and achieved this by preferably denaturing the protein by freezing, etc., and then using a mixed solvent of alcohols and non-polar solvents. The present invention was completed by discovering a method for producing lecithin in high yield by destroying the emulsification system and efficiently extracting lipids, and then easily separating lecithin and neutral oil from this extraction process. ``Means for solving the problem'' In other words, the lipids in frozen egg yolks were mixed with ethanol/n
-Extraction with a mixed solvent consisting of hexane = 25/75 to 15/85, followed by solid-liquid separation.
0.01 to 0.5 times the volume of water to the n-hexane is added, the water-ethanol layer is separated, and the resulting n-hexane layer is treated with an ultrafiltration membrane. This is a method for producing egg yolk lecithin, which is characterized in that high-purity lecithin is obtained at a high yield by volumetric filtration using n-hexane in an amount approximately twice the volume of the n-hexane layer. The present invention will be explained in detail below. In the present invention, when extracting and manufacturing lecithin from egg yolk, first, a mixed solvent consisting of alcohols and a non-polar solvent is added to the egg yolk, and after stirring, solid-liquid separation is performed to extract the lipids containing lecithin. to recover. In this case, the extraction can be carried out efficiently by denaturing the egg yolk protein in advance, preferably by freezing the egg yolk. When egg yolks are used industrially, they are often frozen for hygiene and storage reasons, but in this case, salts such as table salt and sugars such as sugar are added to reduce the denaturation of proteins. Supply used. In the present invention, we have discovered that by freezing the egg yolk as it is, the protein is actively denatured and the subsequent extraction rate is increased. If freezing is hygienic, there is no need to flash freeze the food, and it is sufficient to store it at the temperature at which it is normally shipped frozen. As the alcohol used in the present invention, methanol, ethanol, propanol, etc. can be used, but from the viewpoint of food hygiene, it is preferable to use ethanol. Benzene, hexane, etc. can be used as the non-polar solvent, but it is preferable to use n-hexane, which is currently used for food oil extraction. The amount of mixed solvent used is preferably 1 to 5 times the weight of the frozen egg yolk in terms of extraction efficiency. The mixing ratio of alcohol and non-polar solvent in the mixed solvent used in the present invention is preferably ethanol/n-hexane = 50/50 to 10/90, and more preferably
25/75 to 15/85. As shown in Table 1, when the ratio of alcohol increases, the phospholipid content in the extracted lipids increases, but the total lipid extraction rate decreases.
Undesirable. Moreover, if the ratio of alcohols is low, the total lipid extraction rate will be low, and at the same time, the phospholipid content will also be low, which is not preferable. From these results, the above mixing ratio is preferable.

[Table] Lecithin, neutral lipids, etc. are extracted from the solid-liquid separated solvent phase, but alcohols must be removed during ultrafiltration in the next step. For this purpose, 0.01 to 0.5 parts of water, preferably 0.05 to 0.3 parts, based on the non-polar solvent in the separated solvent phase.
By adding 50% of water, the alcohol is separated and removed from the nonpolar solvent together with water. The alcohol aqueous layer and the nonpolar solvent layer thus separated can be easily separated by decantation or the like. During this process, lecithin was slightly dissolved in the polar solvent consisting of ethanol and water, but if the amount of water added was within the above range, the amount was negligible and could be ignored in industrial production. As a result of studies on adding salts to the water, it was found that by using monovalent metal salts such as sodium chloride and potassium chloride, the distribution of lecithin to the aqueous layer was further reduced and the yield was improved. However, when divalent metal salts such as calcium and magnesium are used, they react with lecithin to form insoluble matter, resulting in a low yield. The resulting n-hexane layer is then passed through a solvent-resistant ultrafiltration membrane to be fractionated into a lecithin component and a neutral lipid component to obtain highly pure lecithin. The ultrafiltration membrane should have a molecular weight cutoff of 5000 or more that can separate lecithin aggregates and neutral lipids, and constant volume filtration and batch filtration may be repeated using the same nonpolar solvent to increase purity. can. As such an ultrafiltration membrane, DUS-40 (cylindrical module, membrane material: polyether sulfone, molecular weight cut off:
40000), Romicon PM-10, 30, 50 and
100 hollow fiber module, membrane material: polysulfone,
The molecular weight cutoff is 5000, 10000, 30000, respectively.
50000 and 100000), manufactured by Mitsui Petrochemical Industries, Ltd.
IRIS-3038 (flat plate module, membrane material: polyacrylonitrile copolymer, molecular weight cutoff: 15,000~
20000 and MPS-3400 (flat plate module, membrane material: polysulfone, molecular weight cutoff: 30000~
40000) etc. "Example" Comparative example 1 1000g of frozen egg yolk, 1000ml of hexane, ethanol
1000 ml of mixed solvent was added, stirred for 5 minutes using a homomixer, and then centrifuged at 3000 rpm for 5 minutes to obtain 1820 ml of solvent. After adding 300 ml of water to this solvent layer and allowing the mixture to stand, decantation was performed to obtain 980 ml of hexane layer. The lipid content in the hexane layer was 25.8%. This was subjected to constant volume filtration using an ultrafiltration membrane DUS-40 (molecular weight cut off: 40,000) manufactured by Daicel Chemical Industries, Ltd. using 3,000 ml of hexane to obtain 82 g of egg yolk lecithin with a purity of 90%. Example 1 1000g frozen egg yolk, 1600ml hexane, ethanol
Add 400ml of mixed solvent, stir for 5 minutes using a homomixer, and then centrifuge at 3000 rpm for 5 minutes to determine the amount of solvent.
A 1960ml solvent layer was obtained. 3% salt solution in the solvent layer
After adding 200 ml of the mixture and allowing it to stand, decantation was performed to obtain a hexane layer of 1,620 ml. The lipid content in hexane was 20.8%. This was subjected to constant volume filtration using 3,000 ml of an ultrafiltration membrane manufactured by Mitsui Petrochemical Industries, Ltd., MPS-3400 (molecular weight cut off: 30,000 to 40,000) to obtain 108 g of 95% pure egg yolk lecithin. "Effects of the Invention" As is clear from the above, according to the present invention, highly purified egg yolk lecithin that can be used in pharmaceuticals can be produced easily, in high yield, and hygienically and safely. The lecithin obtained by the present invention has a very good flavor, unlike that obtained by fractionating acetone, and has high utility value as an emulsifier or surfactant in cosmetics, foods, etc.

Claims (1)

[Claims] 1. Extracting lipids in frozen egg yolk with a mixed solvent consisting of ethanol/n-hexane = 25/75 to 15/85,
The mixed solvent layer obtained by solid-liquid separation contains a monovalent metal salt, and the amount of the n-hexane is 0.01 to
0.5 times the volume of water is added, the water-ethanol layer is separated, and the resulting n-hexane layer is treated with an ultrafiltration membrane.
A method for producing egg yolk lecithin, which comprises obtaining high-purity lecithin at a high yield by volumetric filtration using twice the volume of n-hexane. 2. The manufacturing method according to claim 1, wherein extraction is performed with a mixed solvent of 1 to 5 times the volume of frozen egg yolk. 3. The manufacturing method according to claim 1, wherein the monovalent metal salt is sodium chloride. 4. The manufacturing method according to claim 1, wherein the solvent-resistant ultrafiltration membrane has a molecular weight cut off of 5,000 or more.