JPH1095744A - Production of highly unsaturated aliphatic acid or its alkyl ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily producing a highly purified highly unsaturated aliphatic acid or its alkyl ester from a mixture containing a highly unsaturated aliphatic acid or its alkyl ester without generating a thermally denaturated material in a high yield. SOLUTION: A highly unsaturated aliphatic acid or its alkyl ester is fractionated and concentrated by treating a mixture containing the highly unsaturated aliphatic acid or its alkyl ester by a thin film distillation method, a supercritical gas extraction method and a urea addition method, and performing the supercritical gas extraction method in a process after the thin film distilling method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyunsaturated fatty acid or an alkyl ester thereof. More specifically, the present invention provides a mixture containing a polyunsaturated fatty acid or an alkyl ester thereof, which is separated and concentrated under mild conditions that do not cause thermal denaturation to obtain a highly pure polyunsaturated fatty acid or an alkyl ester thereof. And a method for producing a highly unsaturated fatty acid or an alkyl ester thereof.

[0002]

2. Description of the Related Art It has been known that ethyl eicosapentaenoate having a purity of 90% by weight or more is useful as a drug for improving hyperlipidemia. In addition, it is said that docosahexaenoic acid has an effect of enhancing learning ability. Industrial production of eicosapentaenoic acid, docosahexaenoic acid, or the like or alkyl esters thereof is extremely difficult by chemical synthesis, and must be separated and purified using marine animal and vegetable oils as raw materials. For marine animal and vegetable oils,
Various unsaturated fatty acids having different numbers of carbon atoms and double bonds are contained, and high technology is required to isolate a desired highly unsaturated fatty acid or a derivative thereof from them.

[0003] Many methods have been proposed for the purification of polyunsaturated fatty acids eicosapentaenoic acid, docosahexaenoic acid and derivatives thereof. As such a purification method, a distillation method, a thin film distillation method, a urea addition method, a supercritical gas extraction method, a supercritical chromatography method, a liquid-liquid extraction method, a liquid chromatography method, and the like are known. The distillation method is a method of performing fractionation utilizing a difference in boiling point, and can be separated by a difference in carbon number of an acyl group of a fatty acid. However, it has been impossible to produce ethyl eicosapentaenoate having a purity of more than 90% by weight. Not in. In addition, a concentration method has been proposed in which the purity of eicosapentaenoic acid is increased to 80% by weight or more by combining the distillation method and the liquid-liquid extraction method (Japanese Patent Laid-Open No. 4-1 / 1991).
No. 28250). However, the biggest disadvantage of the distillation method is that
There is a problem that a heat denatured product is formed due to the high temperature of about 200 ° C. during the distillation. When the temperature is high, the amount of the heat-denatured product increases as the distillation time increases, and even if the distillation time is shortened by improving the equipment, the production of the heat-denatured product is completely completed as long as the operation is performed at a high temperature. It cannot be prevented. In the thin film distillation method, the liquid is heated as a thin film, so that the range of the molecule is short and the heat history is small,
It can be distilled at a lower temperature (below the boiling point) than the distillation method,
Thermal denaturation can be reduced. However, there is a problem that the separation power is lower than that of the distillation method because the rectification effect is low.

The urea addition method is a fractionation method utilizing the fact that urea, a saturated fatty acid and a monounsaturated fatty acid easily form an inclusion compound. However, only saturated fatty acids or monounsaturated fatty acids can be separated from a mixture of fatty acids or derivatives thereof, and it is extremely difficult to highly purify highly unsaturated fatty acids only by the urea addition method (Japanese Patent Laid-Open No. 58-1983). 80
No. 37, JP-A-62-72793). The supercritical gas extraction method and the supercritical chromatography method are methods in which carbon dioxide in a supercritical state is used as an extractant, and a target highly unsaturated fatty acid or a derivative thereof is separated by an extraction tower or a column. By changing the solubility in polyunsaturated fatty acids or derivatives thereof by changing the pressure conditions or temperature conditions, it is possible to separate the fatty acid acyl groups by the difference in the number of carbon atoms as in the case of distillation. Alternatively, it is difficult to obtain a highly unsaturated polyunsaturated fatty acid or a derivative thereof having a purity of 90% by weight or more only by supercritical chromatography.

[0005] In the supercritical chromatogram method, it has been proposed to purify docosahexaenoic acid or a derivative thereof using silver nitrate-silica gel as a column packing material. It is difficult to implement the method as an industrial method from the viewpoint of safety and the like (Japanese Patent Laid-Open No. 60-21).
4747, JP-A-64-7906). In addition, as a column packing material, a compound having a free electron pair or a multiple bond in a molecule such as an aminopropyl group, a tetrachlorophthalimide group, a nitro group, or a cyano group as a modifier for the surface of octadecylated silica gel is used as an unsaturated fatty acid. Is disclosed, but there is only an example of only the separation pattern of the chromatogram on a laboratory scale,
No consideration has been given to high purity, and no industrial mass production has been achieved (Japanese Patent Application Laid-Open No. Hei 6-25694).

In the liquid-liquid extraction method, when a mixture of a polyunsaturated fatty acid or a derivative thereof is dissolved in a mixture of a polar solvent and a nonpolar solvent, the partition ratio of the polyunsaturated fatty acid or a derivative thereof to each solvent is determined by the fatty acid. Is a method of concentrating a polyunsaturated fatty acid or a derivative thereof in a polar solvent by utilizing the difference depending on the type of eicosapentaenoic acid and docosahexaenoic acid (JP-A-4-159398, JP-A-4-2185
96, JP-A-4-243849). Also,
In the liquid-liquid extraction method, a method of concentrating silver nitrate in a polar solvent and concentrating a polyunsaturated fatty acid or a derivative thereof has also been proposed.However, it is impossible to economically realize a method using silver nitrate on an industrial scale. It is difficult and cannot be separated by utilizing the difference in the number of carbon atoms (JP-A-64-83043). The liquid chromatography method uses octadecylated silica gel or silica gel-silver nitrate as a carrier and separates them according to the difference in the number of carbon atoms or the number of double bonds. It is difficult to implement as an industrial production method in terms of solvent recovery (Japanese Patent Application Laid-Open Nos. 60-208940 and 63-29).
0845, JP-A-5-287295).

[0007] In any of the above production methods, there is a technical limit in concentrating highly unsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid or derivatives thereof with high purity from marine animal and vegetable oils as raw materials. Implementation was difficult. For this reason, in practical use,
It is said that it is preferable to select a method that appropriately combines various fractionation purification methods. A method of concentrating eicosapentaenoic acid to a purity of 85% by weight or more by combining a distillation method and a urea addition method as a combination of such fractional purification methods (JP-A-4-41457).
Alternatively, a concentration method in which eicosapentaenoic acid has a purity of 80% by weight or more by combining a distillation method and a liquid-liquid extraction method has been proposed (Japanese Patent Publication No. 3-47259). However, since these methods use a distillation method, the polyunsaturated fatty acid or a derivative thereof is exposed to a high temperature of about 200 ° C. at the bottom of the column, and the formation of heat-modified isomers and polymers is not caused. It becomes a problem. That is, according to these production methods, an isomer of eicosapentaenoic acid is mixed into a product of eicosapentaenoic acid, resulting in a decrease in purity. Therefore, it is not suitable as a method for producing a high-purity product with less isomerate. In addition, the heat denatured compound is a compound that does not exist in nature, and may have toxicity when taken into a living body. Therefore, it is preferable to avoid mixing a heat isomer into a product.

On the other hand, there is disclosed a method for producing an eicosapentaenoic acid derivative having a purity of about 90% by weight, which does not contain a heat denatured isomer, by combining a urea addition method and a supercritical gas extraction method using a temperature gradient extraction column. Have been. However, this method uses a raw fish oil having a special fatty acid composition having a high content of eicosapentaenoic acid and a low content of docosahexaenoic acid. The separation of eicosapentaenoic acid and docosahexaenoic acid is insufficient, and the purity of the eicosapentaenoic acid derivative obtained by this method is limited to about 90% by weight, and it has not been possible to obtain industrially with a high yield (Japanese Unexamined Patent Publication No. No. 249102, JP-A 1-2497
No. 42). Also disclosed is a method for purifying esters of eicosapentaenoic acid and docosahexaenoic acid by combining a urea addition method, a thin film distillation method and a supercritical gas extraction method. However, this method is a method for producing a mixture containing at least 80% by weight of eicosapentaenoic acid and docosahexaenoic acid and having a weight ratio of 1: 2 to 2: 1. An acid or a derivative thereof cannot be produced as a single component (JP-A-2-104522).
No.).

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a process for producing a highly pure polyunsaturated fatty acid or an alkyl ester thereof from a mixture containing a polyunsaturated fatty acid or an alkyl ester thereof without producing a heat-denatured product. Easily
Another object of the present invention is to provide a method for producing a highly unsaturated fatty acid or an alkyl ester thereof which can be obtained with a high yield.

[0010]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a mixture containing a polyunsaturated fatty acid or an alkyl ester thereof can be obtained by a thin film distillation method, By combining the extraction method and the urea addition method, and performing a supercritical gas extraction method after the thin film distillation method, a highly pure polyunsaturated fatty acid or an alkyl ester thereof can be produced at a high yield without generating a heat-denatured product. And found that the present invention was completed based on this finding. That is, the present invention
(1) A mixture containing a polyunsaturated fatty acid or an alkyl ester thereof is treated by a thin film distillation method, a supercritical gas extraction method and a urea addition method, and a supercritical gas extraction method is performed in a step subsequent to the thin film distillation method. The method for producing a polyunsaturated fatty acid or an alkyl ester thereof is characterized by separating and concentrating the polyunsaturated fatty acid or an alkyl ester thereof, (2) the polyunsaturated fatty acid is eicosapentaenoic acid or docosahexaenoic acid. The method for producing a polyunsaturated fatty acid or an alkyl ester thereof according to item (1), wherein the alkyl group of the alkyl ester has 1 to 4 carbon atoms, and (3) a polyunsaturated fatty acid separated or concentrated or The highly unsaturated fatty acid or the alkyl ester thereof according to item (1) or (2), wherein the purity of the alkyl ester is 90% by weight or more. The method of manufacturing, there is provided a.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The method of the present invention can be applied to a polyunsaturated fatty acid or an alkyl ester thereof. In the method of the present invention, the polyunsaturated fatty acid is an unsaturated fatty acid having a degree of double bond represented by fatty acid double bond number / (fatty acid carbon number−10) of 0.45 or more. Is, for example, eicosapentaenoic acid (EPA, C
20: 5), docosahexaenoic acid (DHA, C22:
6). Examples of the alkyl ester having an alkyl group having 1 to 4 carbon atoms include polyunsaturated fatty acids and 1 to 4 carbon atoms such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol and tert-butanol. Esters with alcohols can be mentioned. When the number of carbon atoms in the alkyl group of the alkyl ester of the polyunsaturated fatty acid is 5 or more, it may be difficult to achieve sufficient high purity and high yield even by the method of the present invention.
In the method of the present invention, there is no particular limitation on the mixture containing the polyunsaturated fatty acid or its alkyl ester used as a raw material, for example, sardine oil, anchovy oil, saury oil, marine animal oils represented by fish oils such as cod oil, and the like. ,
Examples include those derived from marine animals and plants, such as marine vegetable oil obtained from phytoplankton.

In order to obtain a highly unsaturated fatty acid such as eicosapentaenoic acid or docosahexaenoic acid or an alkyl ester thereof with higher purity, a saponified marine animal or vegetable oil, its esterified product or marine animal or vegetable oil is obtained by alcoholysis. Fatty acid esters and the like can be used,
Ethyl esters of fish oil fatty acids can be used particularly preferably. In addition, saponified marine animal and vegetable oils, esterified products thereof, or fatty acid esters obtained by alcoholysis of marine animal and vegetable oils, are subjected to thin-film distillation or precision distillation at a temperature of 200 ° C. or lower, or purified and concentrated by urea addition treatment. You can use what you did. In particular, when producing a high-purity eicosapentaenoic acid or an alkyl ester thereof having an eicosapentaenoic acid content of 90% by weight or more, the content of eicosatetraenoic acid (C20: 4) affects the purity of the final product. It is preferable to use a raw material having an eicosapentaenoic acid content of 8% by weight or more,
It is more preferable to use a raw material having an eicosapentaenoic acid content of 10% by weight or more. The weight ratio of eicosatetraenoic acid / eicosapentaenoic acid in the raw material is 0.12.
The weight ratio of eicosatetraenoic acid / eicosapentaenoic acid is more preferably 0.1 or less.

In the method of the present invention, the polyunsaturated fatty acid or its alkyl ester is fractionated and concentrated by a combination of a thin-film distillation method, a supercritical gas extraction method and a urea addition method, and the ultra-unsaturated fatty acid or its alkyl ester is treated in a step subsequent to the thin-film distillation method. A critical gas extraction method is performed. The thin film distillation method is a process in which a mixture containing a polyunsaturated fatty acid or an alkyl ester thereof is evaporated and condensed by a condenser when a mixture containing a highly unsaturated fatty acid or an alkyl ester thereof is passed through a heat transfer surface heated under vacuum conditions. It consists of a step of separating into residues that have not evaporated. In the thin-film distillation step, when removing fatty acid components having a boiling point lower than that of eicosapentaenoic acid, having a fatty acid carbon number of 20 or less and a double bond number of 4 or less, the residue fraction is removed at low temperature and low vacuum. Take a minute. In order to increase the eicosapentaenoic acid content, thin film distillation is performed while repeating the residue fraction. In addition, fatty acids having a boiling point higher than eicosapentaenoic acid and having a carbon number of 2
When removing a fatty acid component having 1 or more, 0 or more double bonds, or 20 or more carbon atoms of a fatty acid and 6 or more double bonds, the fractionated fraction is separated under high temperature and high vacuum conditions. Take.
In order to increase the eicosapentaenoic acid content, thin-film distillation is performed while repeating this fractionation.

The thin-film distillation process comprising the residue fractionation and distillate fractionation operations can be repeated, or each can be repeated in an appropriate combination. It is preferable to repeat thin-film distillation of fractionation. Repetition of the thin-film distillation step composed of these operations can be performed by repeating the distillation operation in a batch system or by continuously repeating the distillation operation. In order to avoid a decrease in the yield, the number of repetitions is preferably 2 to 10 times, more preferably 2 to 7 times. The temperature of the heat transfer surface of the thin film still is preferably 50 to 200 ° C, more preferably 60 to 180 ° C. Also,
When the residual fraction is fractionated, the temperature is preferably 60 to 150 ° C., and when the fraction fraction is fractionated, 70 to 180 ° C.
C. is preferred. The degree of vacuum in the thin film still is 1
It is preferably 0 ^{-4 to} 10 Torr, and 5 × 10 ^{-4 to} 5
More preferably, it is Torr. When the residual fraction is fractionated, the pressure is preferably 10 ^{−3 to 5} Torr, and when the fraction fraction is fractionated, the pressure is preferably 5 × 10 ^{−4 to 1} Torr. The flow rate at the time of thin film distillation is preferably 0.05 to 150 l / hr · m ² , and 0.1 to 120 l / hr · m ^2.
More preferably, it is liter / hr · m ² . The type of the apparatus used for the thin film distillation method is not particularly limited, and for example, a known apparatus such as a falling film type thin film distillation apparatus or a centrifugal molecular distillation apparatus can be used.

In the method of the present invention, the extractant used in the supercritical gas extraction method is not particularly limited, and examples thereof include carbon dioxide, ethylene, propylene, ethane, propane, nitrous oxide, chlorodifluoromethane, chlorotrifluoromethane and the like. However, when the final product is a food or pharmaceutical, it is preferable to use carbon dioxide in consideration of handling, safety, toxicity problems due to contamination with the product, and the like. The extraction pressure can be appropriately selected according to the supercritical temperature of the extractant used,
Usually, it is preferably 30 to 300 kg / cm ² , and particularly preferably 72 to 300 kg / cm ² when carbon dioxide is used. The extraction temperature can be appropriately selected according to the supercritical temperature of the extractant to be used, but is usually preferably from 25 to 180 ° C, particularly from 32 to 100 ° C when carbon dioxide is used as the extractant. It is preferred that In addition, the extraction temperature can be a constant temperature of the entire extraction column, or a temperature gradient can be provided in the longitudinal direction of the extraction column. The temperature gradient is preferably set so that the tower bottom temperature is 32 to 70 ° C and the tower top temperature is 40 to 120 ° C, and the temperature difference between the tower top and the tower bottom is 10 to 80 ° C. The extraction column has a multi-stage structure so that a temperature gradient can be imparted in the direction of the column, and a heating device is provided for each stage to enable temperature control, and an arbitrary temperature gradient can be set according to the height position of the extraction column. Preferably, it can be set. The raw material introduction section of the extraction column can be provided at the bottom or middle of the column. The extraction phase is taken out from the upper part of the extraction column, but can be taken out from any stage by providing a take-out port for each stage. As a specific example of the apparatus, an apparatus described in Japanese Patent Application Laid-Open No. 1-249102 can be mentioned.

In the operation of supercritical gas extraction, separation is carried out by controlling the temperature and pressure to take advantage of the difference in the solubility of the polyunsaturated fatty acid or its alkyl ester in the supercritical gas state. In particular, in order to efficiently separate eicosapentaenoic acid and docosahexaenoic acid, it is preferable that the pressure is kept constant and the operating conditions are such that a temperature gradient is provided in the column direction. When producing high-purity eicosapentaenoic acid or its alkyl ester, the above-mentioned temperature gradient is such that the bottom temperature is 32 to 70 ° C and the top temperature is 40 to 120 ° C.
The operation is preferably performed at a temperature of 10 ° C. and a temperature difference between the top and bottom of the tower of 10 to 80 ° C. Alternatively, it is possible to separate the fatty acid mixture by changing the solubility by changing the pressure while keeping the temperature constant. When producing high-purity eicosapentaenoic acid or its alkyl ester, the operation is performed by selecting an arbitrary temperature of 32 to 120 ° C. for the entire column and changing the pressure condition to 72 to 300 kg / cm ^2. It is preferred to do so. By providing a temperature gradient in the column direction and changing the pressure, the solubility of the fatty acid mixture can be changed to separate the mixture. When producing high-purity eicosapentaenoic acid or an alkyl ester thereof, the above-mentioned temperature gradient is set at a column bottom temperature of 32 to 70 ° C,
Top temperature 40 to 120 ° C, temperature difference between top and bottom 10 to 8
Select in an arbitrary range of 0 ° C and set the pressure condition to 72 to 300 kg.
The operation is preferably performed by changing to / cm ² .

In order to produce a high-purity eicosapentaenoic acid or an alkyl ester thereof having a purity of eicosapentaenoic acid of 90% by weight or more, the eicosapentaenoic acid fraction obtained by the first supercritical gas extraction operation is required. The supercritical gas extraction is performed again by combining the fractions with high eicosapentaenoic acid concentration of the forerunner and the later fraction other than the above, or combining the fractions with higher eicosapentaenoic acid concentration of the forerunner or the later fraction, respectively. To collect a high-purity eicosapentaenoic acid fraction and combine it with the fraction obtained in the first time. The yield is further improved by further repeating this operation, but it is preferable to repeat the operation up to about 5 times from the viewpoint of operating efficiency. In the method of the present invention, the polyunsaturated fatty acid or its alkyl ester treated by the supercritical gas extraction method is a polyunsaturated fatty acid or its alkyl ester treated by the thin film distillation method or the thin film distillation method and the urea addition method. In order to obtain a high-purity eicosapentaenoic acid or its alkyl ester having a purity of eicosapentaenoic acid of 90% by weight or more by performing a supercritical gas extraction method, the content of eicosapentaenoic acid or its alkyl ester in the mixture is 40% by weight or more. Preferably, the weight ratio of eicosatetraenoic acid / eicosapentaenoic acid is 0.1 or less, and the weight ratio of docosahexaenoic acid / eicosapentaenoic acid is 0.4 or less.

In the method of the present invention, the urea addition method comprises the steps of: using a mixture containing a polyunsaturated fatty acid or an alkyl ester thereof, a mixture containing a polyunsaturated fatty acid or an alkyl ester thereof after thin-film distillation, or a mixture containing a highly unsaturated fatty acid or an alkyl ester thereof after supercritical gas extraction. Lower alcohols such as methanol, ethanol, propanol and butanol are added to 1 part by weight of a mixture containing unsaturated fatty acids or alkyl esters thereof.
-8 parts by weight and 1-5 parts by weight of urea,
And stir for 0.5-3 hours, then cool to 0-10 ° C,
After filtering out the urea adduct of the precipitated saturated fatty acid and monounsaturated fatty acid, the filtrate can be concentrated. Moreover, the thing which washed the filtrate with water can also be used. Urea forms tetragonal crystals, but when a certain organic compound is present, it has the property of including it and forming hexagonal crystals. In general, in fatty acids, the smaller the number of double bonds and the longer the chain length, the more stable adducts are generated. Therefore, saturated fatty acids and monounsaturated fatty acids mixed in highly unsaturated fatty acids are removed as urea adducts. be able to.

In the method of the present invention, a mixture containing a polyunsaturated fatty acid or an alkyl ester thereof is treated by a combination of three methods, namely, a thin film distillation method, a supercritical gas extraction method and a urea addition method. Purify unsaturated fatty acids or alkyl esters thereof. Among these three methods, the supercritical gas extraction method is performed in a step subsequent to the thin film distillation method, and the urea addition method can be performed at any position in the step. That is, urea addition method, thin film distillation method, supercritical gas extraction method, thin film distillation method, urea addition method, supercritical gas extraction method, or thin film distillation method, supercritical gas extraction method, urea addition method The processing can be performed in order. In the method of the present invention, one or more of the three methods can be repeated twice or more. For example, the thin film distillation method can be repeated twice, such as a thin film distillation method, a urea addition method, a thin film distillation method, and a supercritical gas extraction method. When the supercritical gas extraction method is repeated two or more times, the effect of the present invention can be obtained by performing at least one of the steps as a step after the thin film distillation method.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. The gas chromatography conditions and evaluation methods in the examples are shown below. Gas chromatograph: Hewlett-Packard Company, H
P5890A Carrier gas and flow rate: helium, 1 ml / min Sample concentration: 8 mg / ml (hexane) Injection amount: 1 μl Injection temperature: 250 ° C. Column temperature: From 140 ° C. to 210 ° C., heated at 5 ° C./min Detector temperature: 250 ° C. Detector: FID Column used: DB-WAX (J & W), 30 m × 0.2
5 mm × 0.25 μm Film Split ratio: 100: 1 The content of the isomerate is determined by using the peak not found in the raw material between the peaks of ethyl eicosapentaenoate and ethyl eicosapentaenoate in the gas chromatogram as an isomerate. The ratio to the total fatty acids was shown by weight%. Double bond degree [fatty acid double bond number / (fatty acid carbon number−
10)], the most difficult separation is eicosatetraenoic acid (C) having a double bond degree of 0.4.
20: 4) and the ratio of eicosapentaenoic acid (EPA, C20: 5) having a double bond degree of 0.5, C20: 4 / EPA, was evaluated. The carbon number separation ability was evaluated by determining the ratio of docosahexaenoic acid (DHA, C22: 6) to eicosapentaenoic acid (EPA, C20: 5) and DHA / EPA. Example 1 Eicosapentaenoic acid (EPA, C20: 5) content 1
9.4% by weight, C20: 4 fatty acid content 1.1% by weight (C
20: 4 / EPA = 0.057), docosahexaenoic acid (DHA, C22: 6) content 7.4% by weight (DHA /
EPA = 0.378), a content of fatty acids having 19 or less carbon atoms: 62.1% by weight, a content of fatty acids having 20 carbon atoms: 26.6% by weight, and a fatty acid having 21 or more carbon atoms: 11.3% by weight of fish oil 2.0 kg of ethyl ester was subjected to thin film distillation using a thin film still under the conditions of a temperature of 110 ° C. and a reduced pressure of 0.5 mmHg, and a residue fraction was collected. With respect to this residue fraction, distillation under the same conditions was further repeated a total of 5 times to obtain a residue fraction. Next, this residue fraction was subjected to a temperature of 145 ° C. and a reduced pressure of 0.
A thin film was distilled under a condition of 05 mmHg to collect a distillate. Further, with respect to this distillate, distillation under the same conditions was repeated 5 times in total, and a distillate obtained at the end was collected to obtain an EPA content of 4%.
577 g of 3.7% by weight of ethyl ester were obtained. In addition,
C20: 4 fatty acid content 2.8% by weight, C20: 4 / E
PA = 0.065, DHA content 8.5% by weight, D
HA / EPA = 0.195. 2.6 kg of ethanol and 1.7 kg of urea were added to 577 g of the ethyl ester having an EPA content of 43.7% by weight, followed by stirring at 60 ° C. After cooling the solution to 10 ° C., the precipitated urea adduct was filtered off. The filtrate was concentrated under reduced pressure to an EPA content of 67.
367 g of a 3% by weight ethyl ester were obtained. Note that C2
0: 4 fatty acid content 4.0% by weight, C20: 4 / EPA
= 0.060, DHA content 13.0% by weight, DH
A / EPA = 0.193. Next, 367 g of the ethyl ester having an EPA content of 67.3% by weight was subjected to thin film distillation using a thin film still under the conditions of a temperature of 110 ° C. and a degree of vacuum of 0.5 mmHg, and a residue fraction was collected. Further, the residue fraction was subjected to a temperature of 145 ° C. and a degree of vacuum of 0.05 mmH.
The thin film was distilled under the condition of g, and a fraction was collected to obtain 244 g of ethyl ester having an EPA content of 75.9% by weight. In addition, C20: 4 fatty acid content of 4.3% by weight, C20: 4
/EPA=0.056, DHA content: 9.9% by weight, DHA / EPA = 0.130. This EPA
Using a 6-stage supercritical gas extraction column, a temperature gradient was set to 244 g of ethyl ester having a content of 75.9% by weight so that the top temperature was 70 ° C. and the bottom temperature was 40 ° C. It was supplied from the raw material introduction section. In addition, 120 as a solvent
A high-pressure carbon dioxide gas of kg / cm ² was passed from the bottom of the extraction tower, an extraction phase was taken out from the upper part of the extraction tower, and ethyl ester dissolved in the high-pressure carbon dioxide gas was separated. 4 of all fractions
A fraction of 0 to 70% by weight was collected, and a fraction having a high EPA content in the fore fraction and the after fraction was returned to the raw material part of the extraction column, and subjected to supercritical gas extraction under the same conditions to perform EPA extraction. And the ethyl ester 1 having an EPA purity of 96.1% by weight was combined with the EPA fraction obtained in the first step.
54 g were obtained. The C20: 4 fatty acid content was 3.2% by weight, C20: 4 / EPA was 0.033, and the DHA
/EPA=0.003. Table 1 shows the fatty acid composition of the raw materials, after the thin film distillation, after the addition of urea, after the thin film distillation and after the extraction of the supercritical gas, as well as the double bond separation ability, the carbon number separation ability and the eicosapentaenoic acid yield in each stage. Shown in

[0021]

[Table 1]

Example 2 To 2.0 kg of the same fish oil ethyl ester as in Example 1, 10 kg of ethanol and 6 kg of urea were added and stirred at 60 ° C. After cooling the solution to 10 ° C., the precipitated urea adduct was filtered off. The filtrate was concentrated under reduced pressure to give an EPA content of 53.
710 g of a 6% by weight ethyl ester were obtained. This EPA
710 g of ethyl ester having a content of 53.6% by weight was subjected to thin-film distillation using a thin-film evaporator at a temperature of 110 ° C. and a reduced pressure of 0.5 mmHg, and a residue fraction was collected. With respect to this residue fraction, distillation under the same conditions was further repeated a total of 5 times to obtain a residue fraction. Next, the residue fraction was subjected to thin-film distillation under the conditions of a temperature of 145 ° C. and a degree of reduced pressure of 0.05 mmHg to collect a distillate. Collect the distillate collected,
Ethyl ester having an EPA content of 67.3% by weight
g was obtained. This ethyl ester having an EPA content of 67.3% by weight was prepared by using a supercritical gas extraction column having 6 stages and setting a temperature gradient so that the top temperature was 70 ° C. and the bottom temperature was 40 ° C. From the raw material introduction section. In addition, a high-pressure carbon dioxide gas of 120 kg / cm ² as a solvent was passed through the bottom of the extraction tower, an extraction phase was taken out from the top of the extraction tower, and ethyl ester dissolved in the high-pressure carbon dioxide was fractionated. A fraction of 40 to 70% by weight of all fractions is collected, and a fraction obtained by combining a fraction having a high EPA content in the fore fraction and the after fraction is returned to the raw material part of the extraction column, and supercritical gas extraction is performed under the same conditions. The EPA fraction was collected by fractionation, and the EPA fractions obtained in the first cycle were combined to obtain 190 g of ethyl ester having an EPA purity of 93.1% by weight. The C20: 4 fatty acid content was 4.4% by weight, C20: 4 / EPA was 0.048, the DHA content was 1.0% by weight, and DHA / EPA was 0.0.
It was 11. Table 2 shows the fatty acid composition after the addition of the raw material, urea, thin-film distillation and supercritical gas extraction, as well as the double bond separation ability, carbon number separation ability, and eicosapentaenoic acid yield in each stage.

[0023]

[Table 2]

Example 3 For 2.0 kg of the same fish oil ethyl ester as in Example 1,
Thin film distillation was performed using a thin film still under the conditions of a temperature of 110 ° C. and a degree of vacuum of 0.5 mmHg, and a residue fraction was collected. The residue fraction was further subjected to thin-film distillation under the same conditions five times in total, and the residue fraction was collected to obtain 488 g of an ethyl ester having an EPA content of 43.7% by weight. To 488 g of the ethyl ester having a EPA content of 43.7% by weight, 2.2 kg of ethanol and 1.5 kg of urea were added, followed by stirring at 60 ° C. After cooling the solution to 10 ° C., the precipitated urea adduct was filtered off. The filtrate was concentrated under reduced pressure to an EPA content of 67.
310 g of 1% by weight of ethyl ester were obtained (C20: 4
Fatty acid content: 4.0% by weight, C20: 4 / EPA = 0.0
61). 310 g of the ethyl ester having an EPA content of 67.1% by weight was used in a supercritical gas extraction column having 6 stages,
The temperature gradient was set so that the tower top temperature was 70 ° C. and the tower bottom temperature was 40 ° C., and the mixture was supplied from the raw material introduction section in the middle stage of the extraction column. In addition, a high-pressure carbon dioxide gas of 120 kg / cm ² was passed through the bottom of the extraction column as a solvent, and the extraction phase was taken out from the top of the extraction column.
Ethyl ester dissolved in high-pressure carbon dioxide was separated. A fraction of 40 to 70% by weight of all the fractions is collected, and a combined fraction having a high EPA content of the fore fraction and the after fraction is returned to the raw material portion of the extraction column, and supercritical gas extraction is performed under the same conditions. The EPA fractions were collected, and the EPA fractions obtained in the first cycle were combined to obtain 180 g of ethyl ester having an EPA purity of 93.0% by weight. C20:
(4) Fatty acid content: 4.6% by weight, C20: 4 / EPA = 0.
049, DHA content 1.0% by weight, DHA / E
PA = 0.010. Table 3 shows the raw materials, the fatty acid composition after thin-film distillation, urea addition, and supercritical gas extraction, as well as the double bond separation ability, carbon number separation ability, and eicosapentaenoic acid yield in each stage.

[0025]

[Table 3]

Example 4 For 2.0 kg of the same fish oil ethyl ester as in Example 1,
Thin film distillation was performed using a thin film still under the conditions of a temperature of 110 ° C. and a degree of vacuum of 0.5 mmHg, and a residue fraction was collected. The residue fraction was further subjected to thin-film distillation under the same conditions five times in total, and the residue fraction was collected to obtain 488 g of an ethyl ester having an EPA content of 43.7% by weight. Using a supercritical gas extraction column having 6 stages, a temperature gradient was set to 488 g of the ethyl ester having an EPA content of 43.7% by weight so that the top temperature was 70 ° C. and the bottom temperature was 40 ° C. It was supplied from the raw material introduction section in the middle stage. In addition, 120 kg / cm as a solvent
The high-pressure carbon dioxide gas of No. ² was passed from the bottom of the extraction tower, the extraction phase was taken out from the upper part of the extraction tower, and ethyl ester dissolved in the high-pressure carbon dioxide gas was separated. 40-7 of all fractions
A portion of 0% by weight was collected, and the E
The combined fractions having a high PA content are returned to the raw material section of the extraction column, and supercritical gas extraction is performed under the same conditions to perform EPA.
The fractions were collected, and the EPA fractions obtained in the first run were combined to form 186 g of ethyl ester having an EPA content of 75.3% by weight.
I got Ethanol 850 g and urea 560 g are added to 186 g of the ethyl ester having an EPA content of 75.3% by weight.
Was added and stirred at 60 ° C. After cooling the solution to 10 ° C., the precipitated urea adduct was filtered off. The filtrate was concentrated under reduced pressure to obtain 151 g of an ethyl ester having an EPA content of 91.0% by weight. In addition, C20: 4 fatty acid content 4.3
Wt%, C20: 4 / EPA = 0.047, DH
The A content was 1.7% by weight, and DHA / EPA was 0.019. Table 4 shows the raw material, the fatty acid composition after the thin film distillation, the supercritical gas extraction, and the urea addition, the double bond separation ability, the carbon number separation ability, and the eicosapentaenoic acid yield in each stage.

[0027]

[Table 4]

Comparative Example 1 To 2.0 kg of the same fish oil ethyl ester as in Example 1, 10 kg of ethanol and 7 kg of urea were added and stirred at 60 ° C. After cooling the solution to 10 ° C., the precipitated urea adduct was filtered off. The filtrate was concentrated under reduced pressure to an EPA content of 53.6.
709 g of a% by weight ethyl ester were obtained. 709 g of the ethyl ester having an EPA content of 53.6% by weight was set in a supercritical gas extraction column having 6 stages, and the temperature gradient was set so that the top temperature was 70 ° C. and the bottom temperature was 40 ° C. It was supplied from the raw material introduction section in the middle stage. In addition, 120kg as a solvent
/ Cm ² high-pressure carbon dioxide gas was passed through the bottom of the extraction tower, the extracted phase was taken out from the top of the extraction tower, and the ethyl ester dissolved in the high-pressure carbon dioxide gas was separated. 40 of all fractions
A portion of .about.55% by weight was collected to obtain 103 g of ethyl ester having an EPA purity of 88.9% by weight. C20: 4
Fatty acid content: 4.3% by weight, C20: 4 / EPA = 0.0
48, DHA content 1.8% by weight, DHA / EP
A = 0.021. Raw material, fatty acid composition after urea addition and supercritical gas extraction, and the degree of double bond separation,
Table 5 shows the carbon number separation ability and the yield of eicosapentaenoic acid at each stage.

[0029]

[Table 5]

Comparative Example 2 To 2.0 kg of the same fish oil ethyl ester as in Example 1, 10 kg of ethanol and 6 kg of urea were added and stirred at 60 ° C. After cooling the solution to 10 ° C., the precipitated urea adduct was filtered off. The filtrate was concentrated under reduced pressure to give an EPA content of 53.
709 g of 6% by weight of ethyl ester were obtained. This EPA
Using a supercritical gas extraction column having 6 stages, a temperature gradient of 709 g of ethyl ester having a content of 53.6% by weight was set so that the top temperature was 70 ° C. and the bottom temperature was 40 ° C. It was supplied from the raw material introduction section. In addition, 120 as a solvent
A high-pressure carbon dioxide gas of kg / cm ² was passed from the bottom of the extraction tower, an extraction phase was taken out from the upper part of the extraction tower, and ethyl ester dissolved in the high-pressure carbon dioxide gas was separated. 4 of all fractions
A portion of 0 to 55% by weight was collected, and the EPA content was 88.9.
103 g by weight of ethyl ester were obtained. 103 g of the ethyl ester having an EPA content of 88.9% by weight was subjected to thin-film distillation using a thin-film still at a temperature of 110 ° C. and a reduced pressure of 0.5 mmHg, and a residue fraction was collected. For the residue fraction, distillation under the same conditions was further repeated 5 times in total,
A residue fraction was obtained. Next, the residue fraction was subjected to temperature 1
The thin film distillation was performed under the condition of 45 ° C. and a degree of vacuum of 0.05 mmHg,
A fraction was collected, and distillation under the same conditions was repeated about this fraction a total of five times.
60 g of ethyl ester having an A purity of 91.6% by weight was obtained.
In addition, C20: 4 fatty acid content of 4.1% by weight, C20:
4 / EPA = 0.045, DHA content 1.3% by weight, DHA / EPA = 0.014. Table 6 shows the fatty acid composition after addition of the raw materials, urea addition, supercritical gas extraction and thin-film distillation, as well as the double bond separation ability, carbon number separation ability, and eicosapentaenoic acid yield in each stage.

[0031]

[Table 6]

Table 7 shows the combinations of the steps performed in Examples 1 to 4 and Comparative Examples 1 and 2, and Table 8 shows a summary of the evaluations of the EPA purity and the EPA yield in Examples and Comparative Examples. . However, the EPA purity was rated as x for less than 90 wt%, ○ for 90 wt% or more and less than 92 wt%, and ◎ for 92 wt% or more. The EPA yield is represented by a ratio of ethyl eicosapentaenoate in the final product to ethyl eicosapentaenoate in fish oil as a raw material, wherein x is less than 20%, Δ is 20% or more and less than 30%, and 30% or more is 40%. Less than ○ was evaluated as ○, and 40% or more as ◎.

[0033]

[Table 7]

[0034]

[Table 8]

The ethyl eicosapentaenoate obtained in Example 1 which has been treated by the four steps of the thin film distillation method, the urea addition method, the thin film distillation method and the supercritical gas extraction method has a particularly high purity. Example 2 where treatment was performed in three steps in the order of urea addition method, thin film distillation method and supercritical gas extraction method, and Example 3 where treatment was performed in three steps in the order of thin film distillation method, urea addition method and supercritical gas extraction method
All of the ethyl eicosapentaenoate obtained in the above are high purity and high yield. The ethyl eicosapentaenoate obtained in Example 4 which was treated in three steps in the order of the thin film distillation method, the supercritical gas extraction method and the urea addition method was slightly inferior in both purity and yield as compared with Examples 1 to 3, In addition, purity exceeding 90% by weight is maintained. In contrast, the ethyl eicosapentaenoate obtained in Comparative Example 1, which was treated in two steps in which the urea addition method and the supercritical gas extraction method were combined, had a purity of less than 90% by weight and a yield of Example 2. This is about one half of the yield of 3. Ethyl eicosapentaenoate obtained in Comparative Example 2 in which the supercritical gas extraction method was performed prior to the thin film distillation method although the three steps of the thin film distillation method, the supercritical gas extraction method, and the urea addition method were combined, Purity does not reach 90% by weight and the yield is low. In order to obtain ethyl eicosapentaenoate with high purity and high yield, there are three methods: thin-film distillation, supercritical gas extraction and urea addition. It can be seen that it is necessary to perform the supercritical gas extraction method in a step subsequent to the thin film distillation method in addition to the combination.

[0036]

According to the method of the present invention, from a mixture containing a polyunsaturated fatty acid or an alkyl ester thereof, a highly-purified polyunsaturated fatty acid having a purity of 90% by weight or more or a high-purity unsaturated fatty acid having a purity of 90% by weight or more is produced without producing a heat-denatured product. It is possible to efficiently produce a large amount of alkyl ester in high yield.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C07C 67/60 C07C 67/60 69/587 69/587 C11C 1/08 C11C 1/08 1/10 1/10

Claims (3)

[Claims] A mixture containing a polyunsaturated fatty acid or an alkyl ester thereof is treated by a thin film distillation method, a supercritical gas extraction method and a urea addition method, and a supercritical gas extraction method is carried out in a step subsequent to the thin film distillation method. A method for producing a highly unsaturated fatty acid or an alkyl ester thereof, wherein the highly unsaturated fatty acid or the alkyl ester thereof is separated and concentrated. 2. The method for producing a polyunsaturated fatty acid or an alkyl ester thereof according to claim 1, wherein the polyunsaturated fatty acid is eicosapentaenoic acid or docosahexaenoic acid, and the alkyl group of the alkyl ester has 1 to 4 carbon atoms. . 3. The process for producing a polyunsaturated fatty acid or an alkyl ester thereof according to claim 1 or 2, wherein the purity of the fractionated and concentrated polyunsaturated fatty acid or an alkyl ester thereof is 90% by weight or more.