JPH0158240B2 - - 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).
The present invention relates to a method for concentrating and separating EPA, DHA, or their esters from a raw material mixture containing the lower alcohol 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 them for various medical and other uses. The 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. BACKGROUND OF THE INVENTION Fish oils generally exist as esters of fatty acids and glycerin (glycerides). In its original form, glyceride has a large molecular weight and high vapor pressure, making it extremely difficult to separate, and in the separation process, there are almost no differences due to differences in the constituent fatty acids. Therefore, in order to improve the separation effect, it is common to decompose glyceride into fatty acids or convert it into esters of lower alcohols (generally methyl esters or ethyl esters) before performing the separation operation. Vacuum distillation method, chromatography method, solvent fractionation method, urea addition method, etc. are known as methods for separating fatty acids or their lower alcohol esters.
Both have their advantages and disadvantages. The present invention is a method using carbon dioxide in a liquid or supercritical gas state as an extraction solvent. It is known that carbon dioxide in liquid or supercritical gas state under pressure dissolves various organic compounds and can be used as an extraction solvent. However, simply extracting fatty acids or their esters with carbon dioxide in a liquid or supercritical gas state has little effect on separating the constituent fatty acids according to their types. (Structure of the Invention) Means for Solving the Problems The present invention provides that the solubility of a fatty acid or its ester in carbon dioxide in a liquid or supercritical gas state is
This was completed based on the knowledge that it changes depending on the type of constituent fatty acids and temperature. That is, the present invention heats and refluxes the extraction phase distilled from the upper part of a raw material mixture of various fatty acids or lower alcohol esters containing highly unsaturated fatty acids or lower alcohol esters in an extraction apparatus having a heating reflux section in the upper part. This is a method for concentrating and separating highly unsaturated fatty acids or lower alcohol esters thereof, which comprises extracting with carbon dioxide in a liquid or supercritical gas state, and then removing carbon dioxide from the extraction phase obtained from the apparatus. The pressure in the step of extracting various fatty acids or mixtures of lower alcohol esters containing highly unsaturated fatty acids or lower alcohol esters with liquid or supercritical gaseous carbon dioxide is preferably 70 to 300 atmospheres, particularly when extracting methyl esters or ethyl esters. When extracting esters, a pressure of 100 to 180 atmospheres is suitable. a somewhat higher pressure for fatty acids;
In particular, about 200 atmospheres is preferable. There are no particular restrictions on the extraction temperature, but for ease of operation, a temperature around room temperature, ie, 20 to 40°C, is appropriate. The temperature of the reflux section is 20 to 100°C higher than the extraction temperature. however
Since EPA, DHA, and their esters are unstable to heat, it is desirable that the temperature does not exceed 150°C. By heating or reducing the pressure of the extraction phase distilled from this extraction step, carbon dioxide is rapidly vaporized and easily and completely removed, allowing the fatty acid or its lower alcohol ester fraction to be separated. The carbon dioxide separated in the separation process can be compressed and reused. An example of an apparatus suitable for carrying out the invention is shown in FIG. There is a heating section (heater) at the top of extractor 1.
11 is provided, and a jacket 12 is provided on the side of the extractor. In the jacket 12, constant temperature water is circulated to maintain the extraction temperature at a predetermined value (as described above,
The reflux temperature is maintained at a predetermined value (20 to 100° C. higher than the extraction temperature as described above) by heating the heater 11 with steam or the like. The extractor pressure is kept at a predetermined value by a valve 4. A raw material mixture is put into such an extractor, and carbon dioxide is introduced from a cylinder 2 by a pump 3. The carbon dioxide from which fatty acids or esters have been extracted at low temperatures (20 to 40°C) is heated by the heater 11 at the top, reducing its extraction ability and releasing a portion of the extracted oil. This produces an effect equivalent to reflux in general distillation, resulting in a fractionation effect. However, in general distillation, the fraction is cooled, liquefied, and refluxed, whereas in the method of the present invention, the extracted oil is heated by heating the extraction solvent, carbon dioxide, to reduce its extraction ability. It differs from reflux in general distillation in that part is released and refluxed. As a result, fatty acids with a low degree of saturation and unsaturation or their esters are distilled out in the early stage of extraction, and fatty acids with a high degree of unsaturation or their esters are concentrated and distilled out in the latter half of the extraction operation.
Just separate it. The pressure of the extract is reduced to atmospheric pressure by a valve 4, and carbon dioxide is vaporized, so a fatty acid or its ester fraction is collected in a separation tank 5. Symbol 6 is a gas meter that measures the amount of carbon dioxide used to obtain experimental data. The method of the present invention has a concentration effect even when directly applied to mixtures of fatty acids or their esters obtained from fish oil, etc., but by using raw materials pretreated with other concentration means such as urea addition method, Furthermore, the degree of concentration can be increased. The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto. The raw fatty acid methyl ester mixtures used in Examples 1 to 4 below were prepared by methyl esterifying fish oil (mixed fish oil mainly consisting of sardine oil) in methanol using sodium methoxide as a catalyst. The composition was measured by gas chromatography and expressed as area % of gas chromatography. Example 1 The apparatus shown in FIG. 1 was used. Put 60.9g of fatty acid methyl ester mixture into extractor 1 and set the extraction temperature to
The temperature was set at 40°C and the reflux temperature was 100°C, and carbon dioxide was fed from cylinder 2 to the extractor using pump 3 to start extraction. The extraction pressure is set at 100Kg/cm ² G at the start of extraction, and gradually increases to 150Kg/cm2 at the end of extraction.
cm ² G. The pressure of the extraction phase containing the methyl ester was reduced to atmospheric pressure using a pressure reducing valve 4, and the extracted oil was separated using a separator 5. The carbon dioxide gas from which the extracted oil was separated was calibrated with a gas meter 6 and discharged to the outside of the system.
The extraction took 10 hours and the carbon dioxide used was 18
It was Kg. The composition of the raw materials and representative fractions is
Shown in the table. In the display of ingredients 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] In addition, as the extraction progresses, the methyl esters of EPA and DHA in the extracted components and the total concentration of both are shown in Figure 2. In the figure, the horizontal axis shows the extraction progress rate (%), the vertical axis shows the concentration (%) in the extracted components,
■ indicates EPA methyl ester, ▲ indicates DHA methyl ester, and ● indicates the total concentration of both. (The symbol is the third
The same applies to Figures 1 and 4.) From Table 1 and Figure 2, it can be seen that in the first half of the extraction operation according to the present invention, fatty acid methyl esters with a low degree of saturation or unsaturation are preferentially extracted, and EPA and
It can be seen that methyl esters of highly unsaturated fatty acids such as DHA are intensively extracted in the latter half of the extraction operation. Example 2 The same raw materials and the same equipment as in Example 1 were used.
Put 57.2g of the fatty acid methyl ester mixture into the extractor, set the extraction temperature to 40℃, the reflux temperature to 100℃, and
Reflux extraction was performed at Kg/cm ² G until 50 wt% of the raw material was distilled out, and then the extraction pressure was increased to 150 Kg/cm ² G.
Reflux was stopped and the remaining fraction was extracted. The extraction took 6 hours and used 11 kg of carbon dioxide. As the extraction progresses, the content of the extracted components at that point
Figure 3 shows the methyl esters of EPA and DHA and the total concentration of both. The horizontal axis is the extraction progress rate (%),
The vertical axis indicates the concentration (%) in the extracted components. Example 2 also showed the same tendency as Example 1. Example 3 A test was conducted in combination with urea addition pretreatment. 360 g of methyl ester mixture prepared from fish oil and urea
Ethanol 5 was added to 900 g and refluxed for 30 minutes, then left at room temperature for 1.5 hours, and the resulting solid was filtered out. The residue obtained by distilling off ethanol from the filtrate under reduced pressure was dissolved in n-hexane (1), washed three times with water (40°C) (1), dried over anhydrous sodium sulfate, and then dissolved in n-hexane. Distilled under reduced pressure to obtain a mixture rich in methyl esters of unsaturated fatty acids.
Obtained 142g. 53.8g of this urea-treated methyl ester mixture
into the extractor, extraction temperature 40℃, reflux temperature 100℃
Extracted with. Extraction pressure is 100Kg/cm ² at the start of extraction
Set it to G and gradually increase the pressure to 130 at the end of extraction.
Kg/cm ² G. The compositions of the raw materials and representative fractions are shown in Table 2. Furthermore, as the extraction progresses, the methyl esters of EPA and DHA in the extracted components and the total concentration of both are shown in FIG. 4 at that point. The horizontal axis shows the extraction progress rate (%), and the vertical axis shows the concentration (%) in the extracted components. In Example 3, in which urea addition pretreatment was performed prior to extraction treatment, the concentration ratio of highly unsaturated fatty acid ester was further improved.

[Table] Example 4 A test was conducted in which pretreatment by urea-coexisting carbon dioxide extraction was combined. 87.0 g of a methyl ester mixture prepared from fish oil and 261 g of solid urea (3.0 times the amount of methyl ester) were placed in a urea coexistence extractor, and carbon dioxide was pumped in at an extraction temperature of 40°C and an extraction pressure of 150°C.
Kg/cm ² G was extracted, and the extraction phase was depressurized to atmospheric pressure in a separator. Extraction was performed using 0.40 Nm ³ (0.79 Kg) of carbon dioxide for 1 hour, and 45.2 g (52% of the raw material) of extracted oil was obtained. 40.0 g of the urea coexisting extractor obtained here was placed in extractor 1 of the apparatus shown in FIG. 1, and extraction was carried out at an extraction temperature of 40°C and a reflux temperature of 100°C. The extraction pressure was gradually increased from 100 Kg/cm ² G to 130 Kg/cm ² G at the end of the extraction. The compositions of the raw materials and representative fractions are shown in Table 3.

[Table] Note that in this example, in order to analyze the composition after urea coexistence extraction, the extracted oil was extracted by reducing the pressure once, but the extracted oil was not taken out by separating carbon dioxide after urea coexistence extraction. It is of course also possible to perform a direct reflux extraction. Example 5 48 g of a fatty acid mixture prepared by decomposing fish oil with an aqueous ethanolic potassium hydroxide solution was placed in the extractor 1 of the apparatus shown in Figure 1, and the extraction temperature was
Extraction was carried out at 40°C and reflux temperature of 100°C. Extraction pressure is 180
Gradually increase the pressure from Kg/cm ² G to 200Kg/cm2 at the end.
cm ² G. The extraction took 8 hours and used 21 kg of carbon dioxide. The compositions of the raw materials and representative fractions are shown in Table 4.
The compositional analysis was performed by converting fatty acids into methyl esters.

[Table] (Effects) a) Highly unsaturated fatty acids or their esters can be effectively concentrated and separated from natural oils and fats. b) Carbon dioxide used as a solvent is inexpensive and harmless to the human body. c) Solvent carbon dioxide can be easily and completely removed simply by applying vacuum to the extraction phase. d) Extraction is a low-temperature operation, and the reflux section does not need to be heated too high, so isomerization and polymerization of highly unsaturated fatty acids and the like are less likely to occur.

[Brief explanation of drawings]

FIG. 1 shows an example of an apparatus for carrying out the method of the present invention. Figure 2 shows the EPA in the extracted components of Example 1, Figure 3 shows Example 2, and Figure 4 shows Example 3 as the extraction progresses.
(eicosapentaenoic acid), DHA (docosahexaenoic acid) methyl ester, and the total concentration of both. The horizontal axis shows the extraction progress rate (%), and the vertical axis shows the concentration (%) in the extracted components.

Claims (1)

[Scope of Claims] 1 A raw material mixture of various fatty acids or lower alcohol esters containing highly unsaturated fatty acids or lower alcohol esters thereof is heated in an extraction device having a heating reflux section at the upper part of the extraction phase distilled from the upper part. A method for concentrating and separating highly unsaturated fatty acids or lower alcohol esters thereof, which comprises extracting with carbon dioxide in a liquid or supercritical gas state while refluxing, and then removing carbon dioxide from the extraction phase obtained from the apparatus. 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
℃, and the temperature of the reflux section is 20 to 100 degrees higher than the extraction temperature.
Claim 1 or 2, which is a high temperature
The method described in section. 4. Before extraction, the raw material mixture is treated with urea to separate urea adducts of saturated or low unsaturated fatty acids or their esters, and the concentration of highly unsaturated fatty acids or their esters in the raw materials is increased, and then extracted. A method according to claim 1, 2 or 3, comprising: