JPH0137387B2 - - Google Patents

Description

[Detailed description of the invention]

(Purpose) Industrial application field The present invention is directed to highly unsaturated fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
or EPA in raw materials containing those esters,
This invention relates to a method for concentrating and separating DHA or esters thereof. Problems to be solved by the invention EPA and DHA contained in seafood oils such as fish oil
(and derivatives thereof such as esters and amides) are known to be effective in preventing and treating thrombotic diseases such as myocardial infarction and cerebral infarction. However, since the content in natural products is low, it is necessary to concentrate it for various medical and other uses. An object of the present invention is to provide an effective and economical method for concentrating and separating such highly unsaturated fatty acids or their esters. PRIOR TECHNOLOGY The following methods have been conventionally used to concentrate and separate a specific fatty acid or its ester from a mixture of various fatty acids or its esters, namely (1) distillation method, which requires high vacuum (1 mmHg or less); In addition, because the separation is based on the difference in boiling point, it is difficult to separate highly unsaturated fatty acids or their esters from other fatty acids (saturated and low unsaturated fatty acids) or their esters, and distillation alone requires batch distillation. However, it has the disadvantage that isomerization and polymerization are likely to occur when exposed to high temperatures for a long period of time. (2) Chromatography methods generally only handle small amounts, are extremely difficult to scale up, require a long time to separate, are complicated to operate, and require a large amount of solvent relative to the raw materials. be. (3) The urea addition method takes advantage of the property of fatty acids with a low degree of unsaturation or their esters to form crystals when added to urea, and extracts highly unsaturated fatty acids or their esters from a urea addition mixture with a solvent. This method recovers highly unsaturated fatty acids or their esters from a solution, but if a polar solvent such as methanol is used as an extraction solvent, urea will dissolve and migrate into the extract, so after removing the solvent, the urea must be washed with water or subjected to column chromatography. A process of removing it using As an improvement method, methanol is added to 20%
A method using an aliphatic or alicyclic hydrocarbon solvent containing the following has been proposed (Japanese Patent Application Laid-open No. 57-164196), but this method also requires heating or reduced pressure to remove the solvent after solvent extraction. It is necessary to perform a separation operation. (Structure of the Invention) Means for Solving the Problems The present inventors have discovered that carbon dioxide in a liquid or supercritical gas state selectively extracts highly unsaturated fatty acids or their esters from a urea addition mixture. , completed the invention. That is, the present invention involves bringing a mixture of various fatty acids or lower alcohol esters containing a highly unsaturated fatty acid or a lower alcohol ester thereof into contact with carbon dioxide in a liquid or supercritical gas state, and solid urea, and producing a mixture obtained from the contact area. This is a method for concentrating and separating highly unsaturated fatty acids or their lower alcohol esters by removing carbon dioxide from the extracted phase. This method is the same as the conventional urea addition method in that it utilizes the property of a fatty acid with a low degree of unsaturation or its ester to add to urea, but a liquid Alternatively, the invention is novel and inventive in that it uses carbon dioxide in a supercritical gas state. Since urea does not dissolve in liquid or supercritical gaseous carbon dioxide, the extraction phase consists only of concentrated highly unsaturated fatty acids or lower alcohol esters thereof and carbon dioxide. The pressure of the extraction step is 70 to 300, i.e., the step of contacting various fatty acids or lower alcohol ester mixtures containing highly unsaturated fatty acids or lower alcohol esters, carbon dioxide in a liquid or supercritical gas state, and solid urea. atmospheric pressure, preferably 100
~250 atm, particularly preferably around 200 atm. The temperature is not particularly limited, but for ease of operation, a temperature around room temperature, ie, 20 to 40°C, is suitable. Under these conditions, carbon dioxide exists in a liquid or supercritical gas state. In addition, the amount of solid urea used is 1% per raw material of various fatty acids or their lower alcohol ester mixtures.
~10 times by weight, especially 3 to 8 times by weight is preferred. By heating or depressurizing the extraction phase from this extraction step, the carbon dioxide is rapidly vaporized and can be easily and completely removed, creating a concentrated polyunsaturated fatty acid or its lower alcohol ester that is completely free of urea and solvents. can be separated (separation step). Furthermore, the separation effect is improved by installing two or more separators, reducing the pressure of the extraction phase in two or more pressure stages, and separating concentrated highly unsaturated fatty acids or their lower alcohol esters in each stage. can be done. This is especially true for EPA, DHA
or its ester. The carbon dioxide separated in the separation process can be compressed and reused. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto. The raw materials used in Examples 1 to 6 below are:
Fish oil was used after being alkali-decomposed with an ethanolic potassium hydroxide aqueous solution. The composition of fatty acids is
The fatty acid mixture was made into methyl ester with anhydrous hydrogen chloride methanol solution, and the methyl ester was analyzed by gas chromatography. The composition was expressed as area % on a gas chromatograph. Example 1 The apparatus shown in FIG. 1 was used. Put 52.0 g of fatty acids and 156 g of solid urea (3 times the amount of raw materials) into extractor 1.
Transfer carbon dioxide from cylinder 2 with pump 3, heat it with heater 4 so that the extraction temperature is 25°C,
It was sent to extractor 1 at a constant pressure of 200 Kg/cm ² G. The pressure of the extracted phase was reduced to atmospheric pressure by a pressure reducing valve 5, and the carbon dioxide gas from which the extracted oil was separated by a separator 6 was measured by a gas meter 7 and discharged to the outside of the system. The extracted oil collected in separator 6 was 19.7 g (38% of the raw material). Table 1 shows the compositional analysis values of the raw materials, extracted oil, and raffinate oil. The carbon dioxide used at this time was 1.07Nm ³
(2.09Kg), and the extraction time was 1.5 hours. In the display of fatty acid components in Table 1, for example,
18:2 indicates a fatty acid (linoleic acid) with 18 carbon atoms and 2 double bonds. Eicosapentaenoic acid (EPA) is 20:5, docosahexaenoic acid (DHA)
is 22:6.

[Table] EPA from 18.4% to 22.4%, DHA from 11.1%
It was concentrated to 13.6%. Example 2 The same raw fatty acid mixture and the same equipment as in Example 1 were used. 35.1g fatty acids and 181g solid urea
(5.2 times the amount of raw materials) and put it in extractor 1, 25
℃, 200Kg/cm ² G and 0.64Nm ³ (1.24Kg) of carbon dioxide for 1.5 hours to extract 10.1g of extracted oil (raw material 29
%) was obtained. Composition analysis values are shown in Table 2.

【table】

[Table] EPA from 18.4% to 29.4%, DHA from 11.1%
It was concentrated to 21.5%. Example 3 Using the apparatus shown in Figure 2, the separation pressure of extracted oil was set to 2.
I changed it step by step. 34.7 g of raw fatty acid and 181 g of solid urea (5.2 times the raw material) were mixed and placed in extractor 1, and extracted with carbon dioxide at 40° C. and 200 kg/cm ² G. The extraction phase is 120Kg/cm ² G with pressure reducing valve 5a.
The pressure is reduced to , and a portion of the extracted oil is separated in the separator 6a. The carbon dioxide containing the extracted oil that was not separated in step 6a is further reduced in pressure to atmospheric pressure in pressure reducing valve 5b,
The extracted oil is completely separated in the separator 6a. In this way, when extraction was performed using 0.74Nm ³ (1.54Kg) of carbon dioxide over 1.5 hours, 6.8g (20% of the raw material) was placed in separator 6a and 5.7g was placed in separator 6b.
(17% of raw material) extracted oil was obtained. The results of the compositional analysis are shown in Table 3. In the extracted oil collected in separator 6a, EPA is
DHA was concentrated from 11.1% to 25.0%, from 18.4% to 30.3%. Furthermore, in the extracted oil collected by the separator 6b, EPA was concentrated to 28.3% and DHA was concentrated to 17.3%.

[Table] Examples 4 to 6 The weight of solid urea relative to the raw fatty acid mixture,
1.0 times (Example 4), 2.9 times (Example 5), respectively.
Extraction with carbon dioxide was performed at 40° C. and 200 Kg/cm ³ in the same manner as in Example 3, except that the amount was increased by 8.2 times (Example 6). The concentrations of EPA and DHA contained in the extracted oil and raffinate oil at this time were determined in Example 3.
3 and 4, respectively. In Figure 3, the horizontal axis shows the usage ratio of solid urea with respect to the raw fatty acid mixture, the vertical axis shows the concentration (%) of eicosapentaenoic acid (EPA), and the circle mark shows the concentration (%) of eicosapentaenoic acid (EPA) collected by separator 6a (120Kg/cm ² G). In the extracted oil, □
The marks are in the extracted oil collected in the separator 6b (atmospheric pressure).
The △ mark indicates the EPA concentration in the raffinate oil. In addition, the horizontal axis in Fig. 4 shows the usage ratio of solid urea with respect to the raw fatty acid mixture, the vertical axis shows the concentration (%) of docosahexaenoic acid (DHA), and the circle mark shows the concentration (%) of docosahexaenoic acid (DHA) collected in the separator 6a (120 Kg/cm ² G). In the extracted oil,
The □ mark indicates the DHA concentration in the extracted oil collected by the separator 6b (atmospheric pressure), and the △ mark indicates the DHA concentration in the raffinate oil. It has been shown that the higher the ratio of urea, the better the separation efficiency, and it becomes almost constant at about 8 times the weight. Example 7 Methyl ester mixture prepared from fish oil in methanol with sodium methoxide as catalyst57.9
g and solid urea 170.8g (2.9 times that of methyl ester)
into the extractor shown in Figure 2, and set the extraction temperature to 40
℃, extraction pressure 150Kg/cm ² G, pressure of separator 6a
100Kg/cm ² G, the pressure of separator 6b is atmospheric pressure,
When extracted for 1 hour using 0.26Nm ³ (0.51Kg) of carbon dioxide, 20.3g (of the raw material) was collected in the separator 6a.
35%), 9.8 g (17% of the raw material) of extracted oil was obtained in separator 6b. Composition analysis values are shown in Table 4. In the extracted oil collected in the separator 6a, the methyl ester of EPA was concentrated from 14.7% to 25.8%, and the methyl ester of DHA was concentrated from 12.2% to 19.6%. Also, even the extracted oil collected in the separator 6b,
EPA methyl ester was concentrated at 22.2% and DHA methyl ester at 13.4%.

[Table] *Description of the fatty acid moiety that constitutes the methyl ester Example 8 42.0 g of the same methyl ester mixture as in Example 7
and 253.3 g of solid urea (6.0 times that of methyl ester) were placed in the extractor shown in Figure 2, and the extraction temperature was 40°C, the extraction pressure was 200 Kg/cm ² G, and the pressure of separator 6a was 120 Kg/cm ²
G, assuming the pressure of separator 6b to be atmospheric pressure, 0.15Nm ³
(0.29Kg) of carbon dioxide was extracted over approximately 1 hour, and 15.1g (of the raw material
36%), 5.0 g (12% of the raw material) of extracted oil was obtained in separator 6b. Composition analysis values are shown in Table 5.

[Table] * Describes the fatty acid portion that constitutes methyl ester In the extracted oil collected in separator 6a, methyl ester of EPA was concentrated from 14.7% to 26.2%, and methyl ester of DHA was concentrated from 12.2% to 20.0%. was. Also, even the extracted oil collected in the separator 6b,
EPA methyl ester was concentrated to 24.3% and DHA methyl ester to 16.2%. (Efficacy) a Carbon dioxide used as a solvent is inexpensive and harmless to the human body. b. Since urea is not extracted with carbon dioxide and the solvent carbon dioxide can be easily and completely removed from the extraction phase, highly unsaturated fatty acids or their esters can be effectively concentrated from fatty acids or their esters made from natural fats and oils. Can be separated. c. Since extraction can be carried out at low temperatures, isomerization and polymerization of highly unsaturated fatty acids etc. are unlikely to occur.

[Brief explanation of drawings]

Figure 1 is a diagram showing the equipment used in Examples 1 and 2, Figure 2 is a diagram showing the equipment used in Examples 3 to 8, and Figure 3 is a diagram showing the equipment used in Examples 3 to 8. Figure 4 shows the change in the concentration of eicosapentaenoic acid (EPA) in the concentrated isolate when the ratio of solid urea to the raw fatty acid mixture was changed. FIG. 2 is a diagram showing changes in concentration of DHA).

Claims (1)

[Claims] 1. Various fatty acids containing a highly unsaturated fatty acid or a lower alcohol ester thereof, or a mixture of lower alcohol esters thereof, carbon dioxide in a liquid or supercritical gas state, and solid urea are brought into contact, and the contact area A method for concentrating and separating highly unsaturated fatty acids or their lower alcohol esters, which comprises removing carbon dioxide from the extracted phase obtained from 2. The method according to claim 1, wherein the highly unsaturated fatty acid is eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA). 3 Extraction pressure is 70 to 300 atm, extraction temperature is 20 to 40
The method according to claim 1 or 2, wherein the temperature is .degree. 4. Claims 1, 2, or 3 in which the extraction phase is depressurized in two or more pressure stages to separate the highly unsaturated fatty acids or lower alcohol esters thereof concentrated in each stage. the method of.