JP7264345B2 - fat extraction method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for extracting fats and oils.

As a method for extracting fats and oils from fat-containing substances, oil expression by pressing or extraction using an organic solvent such as hexane as an extraction solvent is used. Moreover, Patent Document 1 discloses a method for extracting oils and fats using supercritical or subcritical carbon dioxide.

Rice bran oil, which is obtained as a by-product of rice, is obtained by solvent extraction. The raffinate (defatted rice bran) after oil is extracted is used as a fertilizer or the like. In general, fats and oils obtained from plants are used as raw materials for biodiesel in addition to raw materials for foods and cosmetics.

JP 2015-168718 A

In the extraction of oils and fats with an organic solvent such as hexane, many contaminants are dissolved together with the oils and fats from plants, so many post-treatment processes such as refining are required for use in foods, cosmetics, fuels, and the like. In particular, since a large amount of phosphorus such as phospholipids is extracted as contaminants, when the obtained contaminant-containing oil is used for biodiesel fuel, the phosphorus remaining without being burned is clogged in the injection nozzle of the diesel engine. There is a problem of causing trouble.

In addition, extraction using supercritical or subcritical carbon dioxide requires a high pressure of, for example, 15 MPa or higher, so the cost of manufacturing the apparatus is high and the operation of the apparatus is dangerous.

An object of the present invention is to provide a method capable of extracting fats and oils at a high yield under milder conditions.

In the present invention, a medium containing carbon dioxide and a non-polar liquid solvent and having a liquid continuous phase (hereinafter also referred to as an "extraction medium") is permeated into a fat-containing substance containing phosphorus, whereby the fat-containing substance is To provide a method for extracting fats and oils, comprising extracting fats and oils from

Preferably, the molar ratio of non-polar liquid solvent to carbon dioxide in the extraction medium is 0.18:0.82 to 0.05:0.95. When the molar ratio is within this range, fats and oils can be extracted with a higher yield, and contaminants such as phosphorus in the resulting fats and oils can be further reduced.

In the above extraction method, the extraction is preferably carried out at a temperature of 20-40° C. and a pressure of 2-7 MPa. By performing the extraction under the above conditions, fats and oils can be extracted with a higher yield and with less contaminants.

The oil-and-fat-containing material may be a plant material. Preferably, the plant material is rice bran.

According to the extraction method of the present invention, fats and oils can be extracted with a high yield under milder conditions.

FIG. 2 shows the phase equilibrium of the hexane-carbon dioxide system at 25° C.; It is a graph which shows the fats-and-oils extraction amount with respect to extraction medium consumption. 4 is a graph showing the ratio of the amount of fat extracted by extraction media with various carbon dioxide mole fractions to the amount of fat extracted by hexane extraction. It is a graph which shows the phosphorus concentration in fats-and-oils extraction amount with respect to a carbon-dioxide mole fraction. (a) is a photograph showing oil extracted by hexane extraction, and (b) is a photograph showing oil extracted by an extraction medium.

DETAILED DESCRIPTION OF THE INVENTION Embodiments for carrying out the present invention will be described in detail below. However, the present invention is not limited to the following embodiments.

The extraction method according to the present embodiment uses a medium (extraction medium) containing a non-polar liquid solvent and carbon dioxide and having a liquid continuous phase. It can be confirmed with the naked eye that the continuous phase is liquid. Normally, dissolving carbon dioxide in a polar solvent such as water hardly increases the volume of the solvent, but dissolving carbon dioxide, which is also non-polar, in a non-polar liquid solvent greatly expands the volume of the liquid solvent. phenomenon can be seen. Also in the extraction medium according to the present embodiment, the carbon dioxide gas can be dissolved in the non-polar liquid solvent to form an expanded liquid state. In addition, when the carbon dioxide gas cannot be completely dissolved in the non-polar liquid solvent, the continuous phase is liquid, and bubbles are dispersed therein. The extraction solvent according to the present embodiment is either the case where all of the carbon dioxide gas is dissolved in the nonpolar liquid solvent, or the case where part of the carbon dioxide gas is dispersed in the liquid as bubbles. Also, the continuous phase is liquid.

When a non-polar liquid solvent is used alone for fat extraction, it has a strong ability to dissolve (extract) fat from fat-containing substances, but it also dissolves a large amount of contaminants such as phosphorus as well as fat. In addition, since the non-polar liquid solvent alone has a weak penetrating power into the oil-containing material, the amount of oil extracted from the oil-containing material is small. On the other hand, the extraction medium according to the present embodiment has a high dissolving power, a small amount of impurities such as phosphorus dissolved therein, and an ability to selectively dissolve fats and oils. In addition, since the extraction medium according to the present embodiment has a strong penetrating power into the oil-containing material, it easily penetrates into the oil-containing material, and dissolves the oil not only from the surface of the oil-containing material but also from the inside with high efficiency. be able to. The reason why the extraction medium according to the present embodiment has high penetration power is that the non-polar liquid solvent is diluted with carbon dioxide to reduce the viscosity of the liquid solvent.

FIG. 1 is a graph showing the hexane-carbon dioxide vapor-liquid equilibrium at 25° C. as an example of the non-polar liquid solvent-carbon dioxide phase equilibrium. Nonpolar liquid solvent-carbon dioxide systems change phase states with temperature, pressure, and mole fractions. The solid line in the graph is the boundary between the region where the phase is only the liquid phase and the region where the system has two phases, the gas phase and the liquid phase. In the liquid phase, carbon dioxide gas is dissolved in a non-polar liquid solvent. In the gas-liquid two-phase region, carbon dioxide that cannot be completely dissolved in the non-polar liquid solvent forms a gas phase. For example, when the system is in the liquid phase only, the pressure and temperature are kept constant while the carbon dioxide mole fraction is gradually increased, or the nonpolar liquid solvent and carbon dioxide mole fraction and temperature are kept constant. If the pressure is gradually lowered while the solution is still in place, undissolved carbon dioxide appears as bubbles. The dashed line in the graph is the boundary between the region in which the system has two gas-liquid phases and the region in which the system has only the gas phase. In the extraction method according to the present embodiment, the phase of the extraction medium may be a liquid phase alone or a gas-liquid two phase.

The extraction medium according to this embodiment is different from carbon dioxide in a supercritical state. In the extraction method according to the present embodiment, the extraction temperature and pressure may be within a range in which carbon dioxide does not enter a supercritical state, and are less than 31.1° C. or less than 7.4 MPa.

The extraction temperature is preferably 40° C. or lower, more preferably 30° C. or lower. The lower limit of the extraction temperature is not particularly limited, but considering that the operation is performed at room temperature, it may be 10° C. or higher, for example.

The extraction pressure is preferably less than 10 MPa, more preferably 7 MPa or less. The extraction pressure may be, for example, 2 MPa or higher, preferably 3 MPa or higher, and more preferably 4 MPa or higher. The extraction pressure is preferably close to 0.1 MPa as long as the amount of dissolved fats and oils is large and the amount of impurities dissolved is small. The extraction method according to this embodiment can be performed at a lower pressure than the extraction method using supercritical or subcritical carbon dioxide.

In the extraction medium according to the present embodiment, the content ratio of the non-polar liquid solvent and carbon dioxide may be such that the continuous phase of the extraction medium can be maintained in the liquid phase. The extraction medium used in the extraction method of the present embodiment tends to have higher dissolving power, that is, the ability to extract fats and oils from fat-containing substances, as the molar fraction of the nonpolar liquid solvent increases. The molar ratio of the non-polar liquid solvent to the total amount of the non-polar liquid solvent and carbon dioxide in the extraction medium of this embodiment is preferably 0.05 or more, 0.07 or more, 0.10 or more, 0.07 or more, 0.10 or more, It may be 12 or more, 0.15 or more, or 0.18 or more. The molar ratio of non-polar liquid solvent to the total amount of non-polar liquid solvent and carbon dioxide in the extraction medium may be, for example, 0.4 or less.

Also, the higher the molar fraction of carbon dioxide in the extraction medium, the lower the content of contaminants, especially phosphorus, in the resulting extract. In this embodiment, the molar ratio of carbon dioxide to the total amount of non-polar liquid solvent and carbon dioxide in the extraction medium is preferably 0.6 or more. The molar ratio of carbon dioxide to the total amount of non-polar liquid solvent and carbon dioxide in the extraction medium may be, for example, 0.95 or less.

In the extraction method according to the present embodiment, the molar ratio of the nonpolar liquid solvent and carbon dioxide in the extraction medium is preferably 0.18:0.82 to 0.05:0.95, preferably 0.15:0. 0.85-0.07:0.93, or 0.12:0.88-0.10:0.90. In this specification, the molar ratio of the non-polar liquid solvent and carbon dioxide in the extraction medium refers to the molar ratio of the entire phase of the extraction medium. refers to the sum of the molar ratios present in

The extraction medium according to this embodiment preferably consists essentially of a non-polar liquid solvent and carbon dioxide. The total amount of the nonpolar liquid solvent and carbon dioxide in the extraction medium is, for example, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, or 99.5% by mass or more, relative to the total amount of the extraction medium. It may be 8% by mass or more.

The extraction temperature, extraction pressure, and molar ratio of non-polar liquid solvent to carbon dioxide may be within a range that allows the continuous phase of the extraction medium to remain liquid. For example, the extraction conditions are preferably a combination of 10 to 40° C., 2 to 10 MPa, and a molar ratio of the nonpolar liquid solvent and carbon dioxide of 0.18:0.82 to 0.05:0.95. , 20 to 40 ° C., 2 to 7 MPa, and the molar ratio of the nonpolar liquid solvent and carbon dioxide is more preferably a combination of 0.18: 0.82 to 0.05: 0.95, 20 to 30 C., 4 to 6 MPa, and a molar ratio of the non-polar liquid solvent to carbon dioxide of 0.15:0.85 to 0.07:0.93.

Non-polar liquid solvents can be, for example, hydrocarbons, ketones such as acetone, ethers such as tetrahydrofuran. Hydrocarbons may be, for example, alkanes, alkenes, alkynes, cycloalkanes, or aromatic hydrocarbons. The hydrocarbon preferably has 5 or more carbon atoms, more preferably 5 to 12 carbon atoms. The nonpolar liquid solvent may be used singly or in combination of two or more.

In the extraction method according to the present embodiment, the amount of the extraction medium used per 1 g of the fat-containing material may be, for example, 2 g or more, 3 g or more, 5 g or more, 8 g or more, or 10 g or more. The amount of extraction medium used may be, for example, 20 g or less or 15 g or less per 1 g of the oil-containing material.

Since the extraction method according to the present embodiment can extract fats and oils from the fat-containing material with high efficiency, it is possible to perform extraction in a short time. The extraction time may be appropriately set according to the shape, size, etc. of the oil-containing substance to be extracted. The extraction time can be, for example, 1 hour to 3 hours. Since the extraction method according to the present embodiment can extract fats and oils with high efficiency, for example, it can be a semi-continuous method in which the extraction medium is continuously supplied to the fat-containing material.

In the extraction method according to the present embodiment, the fat-containing substance to be extracted may contain phosphorus such as phospholipids and fats and oils. The oil-and-fat-containing material may contain components such as water and free fatty acids. The oil- and fat-containing material may be, for example, a plant material. Plant sources may be, for example, rice bran, soybean, rapeseed, sesame, sunflower, safflower, cottonseed, peanut, olive, palm, corn germ, pongamia, jatropha, and the like. As the plant material to be extracted, the collected material may be used directly, or the dried material, or the residue after oil extraction by oil extraction may be used. Preferably, the plant material is rice bran, cottonseed, sunflower seed, or their residues after oil extraction. When the oil-containing material contains moisture, it is preferable that the moisture content is reduced by a treatment such as drying. In addition, since the extraction method according to the present embodiment has a high extraction efficiency, it is also effective for oil-containing substances that have a low oil content and are not suitable for oil extraction by compression.

The oil-containing substance preferably has a particle size of, for example, about 0.5 to 10 mm, and may have a particle size of 0.5 to 5.0 mm or 0.5 to 3.0 mm. The oil-and-fat-containing material is preferably crushed and/or pulverized in order to increase extraction efficiency.

The extraction method according to this embodiment may comprise preparing an extraction medium. The extraction medium can be prepared, for example, by mixing a non-polar liquid solvent and carbon dioxide, each pre-adjusted to temperature and pressure. The extraction medium may be obtained by mixing the oil-containing substance to be extracted, the non-polar liquid solvent, and the carbon dioxide, and adjusting the temperature and pressure to a predetermined level.

The penetration of the extraction medium into the fat-containing material can be carried out by bringing the extraction medium into contact with the fat-containing material. It is preferable to impregnate the oil-containing substance with the extraction medium in a heat-resistant and pressure-resistant container that can maintain the state of the extraction medium. By permeating the oil-containing material with the extraction medium, the oil dissolves from the oil-containing material, and an extraction medium containing the oil can be obtained.

Extraction yields an extraction medium in which fats and oils are dissolved. The extraction medium can then be decompressed to atmospheric pressure to release the carbon dioxide in the extraction medium as a gas. The non-polar liquid solvent in which the oil and fat are dissolved after decompression can be separated by heating under reduced pressure to evaporate the non-polar liquid solvent by utilizing the difference in boiling points. The separated non-polar liquid solvent may be recovered and reused. The extraction method according to this embodiment may include separating the non-polar liquid solvent and the fat.

By the extraction method according to the present embodiment, fat can be extracted from the fat-containing material. Fats and oils refer to glycerides (monoglycerides, diglycerides and triglycerides). The fats and oils obtained by the extraction method according to the present embodiment tend to have little impurities such as phosphorus-containing substances such as phospholipids, water and wax, and have high transparency. By the extraction method according to the present embodiment, it is possible to achieve a yield of oils and fats comparable to that of extraction with supercritical or subcritical carbon dioxide under milder conditions.

The fats and oils obtained by the extraction method according to the present embodiment may then be subjected to post-treatments such as deoxidation, dephosphorization, dewaxing and other refining treatments and dehydration treatments, if necessary. The obtained fats and oils can be used, for example, in the production of foods, cosmetics, etc., and can be used as biodiesel fuel, depending on their properties. Since the fats and oils obtained by the extraction method according to the present embodiment contain few contaminants, they can be used as they are without post-treatment, for example, for biodiesel fuel.

EXAMPLES The present invention will now be described more specifically based on examples. However, the present invention is not limited by the following examples.

[sample]
Rice bran obtained from a rice mill in Hamamatsu City, Shizuoka Prefecture was used as the oil-and-fat-containing material to be extracted. The rice bran was passed through a sieve of 500 μm mesh to remove husks and the like, and used for extraction.

[Extraction with hexane]
The amount of oil extracted from rice bran was investigated using only hexane as an extraction solvent. 50 g of rice bran was immersed in g of hexane at room temperature (25° C.) and stirred under atmospheric pressure for 24 hours to obtain hexane in which oils and fats were dissolved.

[Measurement of oil content]
Hexane and oil were separated by vacuum distillation and evaporation of hexane. The amount after hexane was separated was weighed as the amount of fat.

[Measurement of phosphorus content]
The phosphorus concentration in the obtained extracted oil was measured by the following method. After baking 0.2 g of the extracted fat at 450° C. for 3 hours, 20 mL of 1 mol/L hydrochloric acid was added and stirred for 16 hours. After filtering the solution, it was diluted with distilled water to 50 ml, and the phosphorus concentration was measured by ICP plasma emission spectrometry.

The amount of oil obtained by hexane extraction was an average of 0.225 g per 1 g of rice bran used. The average phosphorus concentration in the resulting mixture was 323 ppm.

[Extraction with extraction medium]
In the following test examples, fats and oils were extracted from rice bran using an extraction medium consisting of hexane and carbon dioxide. 50 g of rice bran was placed in a pressure vessel and the temperature was kept at 25-27°C. An extraction medium was prepared by mixing hexane and carbon dioxide at a given pressure, temperature and mole fraction. The extraction medium was passed through a pressure vessel containing rice bran at a constant flow rate. From the pressure vessel, the extraction medium in which the oil and fat after extraction were dissolved was discharged at the same speed as the inflow speed. The resulting oil-dissolved extraction medium was depressurized to atmospheric pressure to release carbon dioxide into the atmosphere. On the other hand, fats and oils and hexane were separated by distillation under reduced pressure. The amount of phosphorus in the extracted fat was measured by the same method as for the hexane extraction.

Whether the extraction medium is a system with only a liquid phase (one phase) or a system consisting of a gas phase and a liquid phase (two phases) is determined from the supply ratio of hexane and carbon dioxide and the phase diagram in FIG. bottom.

(Study 1)
Changes in the amount of oil extracted with an increase in extraction medium consumption were investigated under the same conditions of a hexane:carbon dioxide molar ratio of 0.10:0.90, an extraction temperature of 27°C, and an extraction pressure of 5 MPa. . The results are shown in FIG. FIG. 2 is a graph showing the amount of oil obtained per gram of rice bran versus the consumption of extraction medium (grams) per gram of rice bran. On the other hand, the dashed line in the figure indicates the average value (0.225 g) of the amount of fat and oil extracted with hexane alone under atmospheric pressure and room temperature. The amount of oil and fat extracted by the extraction medium increased as the consumption of the extraction medium increased, and peaked out at around 0.8 g of extraction medium consumption per 1 g of rice bran. was also 15% higher.

(Review 2)
The relationship between the hexane:carbon dioxide molar fraction in the extraction medium and the amount of fat extracted was investigated. The molar fraction of carbon dioxide in the extraction medium consisting of hexane and carbon dioxide is varied in the range of 0.81 to 0.95, the pressure is adjusted in the range of 4.6 to 5.3 MPa, and other conditions are adjusted. Extraction with an extraction medium from rice bran was performed uniformly, and the amount of extracted oil and fat was measured. The results are shown in FIG. FIG. 3 shows the ratio of the amount of fat and oil extracted with the extraction medium to the amount of fat and oil extracted from 1 g of rice bran with hexane alone. In any example of carbon dioxide mole fraction, the amount of oil extracted per 1 g of rice bran with the extraction medium was at least about 10% higher than in the case of extraction with hexane alone at atmospheric pressure and room temperature. Furthermore, it was confirmed that the system has a high fat-and-oil extracting power whether the system has only a liquid phase or has two gas-liquid phases.

(Review 3)
The relationship between the hexane:carbon dioxide molar fraction in the extraction medium, the amount of fat extracted per 1 g of the extraction medium, and the phosphorus concentration in the extracted fat was investigated. The molar fraction of carbon dioxide in the extraction medium consisting of hexane and carbon dioxide is varied in the range of 0.81 to 0.95, the pressure is adjusted in the range of 4.6 to 5.3 MPa, and other conditions are adjusted. Extraction with an extraction medium from rice bran was performed uniformly, and the amount of fat extracted and the phosphorus concentration in the extracted fat were measured. The results are shown in FIG.

The vertical axis on the left side of FIG. 4 indicates the amount of oil extracted per 1 g of the extraction medium. There was a tendency that the lower the carbon dioxide mole fraction, the higher the oil extraction amount. The vertical axis on the right side of FIG. 4 shows the phosphorus concentration in the obtained oil. It was confirmed that when the carbon dioxide mole fraction is 0.82 or more, the phosphorus concentration in the oil is particularly suppressed.

FIG. 5 shows an example of fats and oils obtained by hexane extraction (a) and extraction medium extraction (b). The fats and oils in FIG. 5(b) were extracted at 27° C., 5 MPa, and a molar ratio of hexane:carbon dioxide=0.10:0.90. The oil and fat obtained by the extraction medium contained less contaminants adhering to the glass container and had higher liquid transparency than the oil and fat obtained by the hexane extraction.

Claims (4)

extracting fat from a fat-containing substance containing phosphorus by permeating a fat-containing substance containing carbon dioxide and a non-polar liquid solvent, wherein the continuous phase is a liquid , into the fat-containing substance; A method for extracting oils and fats, wherein the molar ratio of the liquid solvent and carbon dioxide is 0.19:0.81-0.05:0.95, and the extraction is carried out at a temperature of 20-40° C. and a pressure of 2-7 MPa. The method according to claim 1, wherein the molar ratio of non-polar liquid solvent and carbon dioxide in said medium is from 0.18:0.82 to 0.05:0.95. 3. The method according to claim 1 or 2 , wherein the fat-containing substance is a plant material. 4. The method of claim 3 , wherein the plant material is rice bran.

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