Caffeine removal method of unroasted coffee beans

Abstract

To provide a caffeine removal method of unroasted coffee beans capable of removing caffeine by extracting caffeine from the unroasted coffee beans, by suppressing deterioration of original flavor of coffee beans caused by removal of lipid or the like.SOLUTION: A removal method of caffeine from unroasted coffee beans includes: moistening the unroasted coffee beans by bringing them into contact with water; storing the moistened unroasted coffee beans in an extraction vessel 10; obtaining water-containing carbon dioxide by bringing the carbon dioxide from a cylinder 12 into contact with water (vessel 16); introducing the water-containing carbon dioxide into the extraction vessel 10 to contact the moistened unroasted coffee beans; pressurizing the carbon dioxide to a supercritical state; reducing the pressure to a non-supercritical state; and repeatedly cycling the pressurization and depressurization several times to extract and remove caffeine from the unroasted coffee beans.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for decaffeinating green coffee beans. [Background technology]

[0002] The caffeine contained in coffee has desirable effects such as stimulating and awakening the brain, increasing concentration and cognitive ability, and improving motor function. However, if consumed in excess, it can also pose health risks. As a result, demand for decaffeinated coffee, which has had the caffeine removed, has increased in recent years in line with growing health consciousness.

[0003] A known method for removing caffeine from unroasted coffee beans is to treat the unroasted coffee beans with water to extract and remove the caffeine.

[0004] In addition, a method for removing caffeine from unroasted coffee beans is known in which unroasted coffee beans are treated with supercritical carbon dioxide to extract and remove the caffeine. The extraction method using supercritical carbon dioxide is highly safe as no solvent remains in the coffee, and it is possible to extract caffeine highly efficiently by adjusting the pressure, temperature, etc. to the optimal conditions, so it is widely used in the decaffeinated process.

[0005] On the other hand, there is an increasing demand for coffee to retain the original flavor of the coffee beans, and the same is expected of decaffeinated coffee.

[0006] Patent Document 1 describes a method for removing caffeine from unroasted coffee beans (green coffee) using a supercritical fluid of carbon dioxide.

[0007] Patent Document 2 describes a method for removing caffeine from unroasted coffee beans, in which unroasted coffee beans are moistened by contacting them with water at a temperature of 30° C. or higher and 90° C. or lower, and then caffeine is extracted and removed from the moistened unroasted coffee beans using supercritical carbon dioxide. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 3-160949 [Patent Document 2] JP 2023-074596 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, the method of extracting and removing caffeine by treating unroasted coffee beans with water has a high caffeine extraction rate, but requires a large amount of water, and has the problem that the original taste of the coffee beans is deteriorated because the components contained in the coffee beans are also extracted and removed at the same time as the caffeine is extracted and removed. Also, the method of extracting and removing caffeine by treating unroasted coffee beans with supercritical carbon dioxide requires a large amount of carbon dioxide for extraction, and has the problem that the components such as lipids contained in the coffee beans are also extracted and removed at the same time as the caffeine is extracted and removed, resulting in a deterioration of the original taste of the coffee beans.

[0010] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a method for removing caffeine from unroasted coffee beans, which can extract and remove caffeine from unroasted coffee beans while suppressing deterioration of the original taste of the coffee beans due to the removal of lipids, etc. [Means for solving the problem]

[0011] The method for removing caffeine from unroasted coffee beans of the present invention involves bringing unroasted coffee beans into contact with water to moisten them, placing the moistened unroasted coffee beans in an extraction vessel and bringing them into contact with water to obtain moistened carbon dioxide, introducing the moistened carbon dioxide into the extraction vessel to bring it into contact with the moistened unroasted coffee beans, pressurizing the carbon dioxide to a supercritical state and reducing the pressure to a state that is not in the supercritical state, and repeating this cycle of pressurization and depressurization multiple times to extract and remove caffeine from the unroasted coffee beans. Effect of the Invention

[0012] According to the present invention, it is possible to suppress the deterioration of the original taste of the coffee beans caused by the removal of lipids, etc., and to extract and remove caffeine from unroasted coffee beans. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an extraction apparatus using supercritical carbon dioxide according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating pressure changes in an extraction method using supercritical carbon dioxide according to an embodiment. [Diagram 3] FIG. 3 is a graph showing the caffeine extraction rate versus the amount of carbon dioxide in verification experiment 1. [Figure 4] FIG. 4 is a graph showing the caffeine extraction rate versus the amount of carbon dioxide in verification experiment 2. [Diagram 5] FIG. 5 is a graph showing the caffeine extraction rate versus the amount of carbon dioxide in verification experiment 3. [Figure 6] FIG. 6 is a graph showing the caffeine extraction rate versus the amount of carbon dioxide in verification experiment 4. [Figure 7] FIG. 7 is a graph showing the caffeine extraction rate versus the amount of carbon dioxide in verification experiment 5. [Figure 8] FIG. 8 is an optical microscope photograph of a cross section of an unroasted coffee bean in verification experiment 6. [Figure 9]FIG. 9 is an explanatory diagram illustrating the transfer of carbon dioxide and caffeine in a method for removing caffeine from unroasted coffee beans. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Outline of the present invention> The present inventors investigated the pressure profile of supercritical carbon dioxide when removing caffeine from unroasted coffee beans, and the removal of caffeine and lipids with and without the inclusion of water in carbon dioxide.

[0015] As a result, the inventors have found conditions under which caffeine can be efficiently removed while suppressing the removal of lipids by repeating a cycle of pressurizing and depressurizing the carbon dioxide containing water to make the carbon dioxide supercritical and then depressurizing the carbon dioxide to a non-supercritical state multiple times. The present invention is based on this finding.

[0016] <Embodiment> (Extraction device 1) FIG. 1 is a schematic diagram showing the configuration of an extraction apparatus 1 using supercritical carbon dioxide according to this embodiment. The extraction apparatus 1 has an extraction vessel 10. The extraction vessel 10 is housed inside an oven 11. An inlet provided at the lower end of the extraction vessel 10 is connected to a cylinder 12 that supplies carbon dioxide. A pump 13, a pressure gauge 14, a thermocouple 15, and a vessel 16 are provided on the supply path of carbon dioxide from the cylinder 12 to the extraction vessel 10. An outlet provided at the upper end of the extraction vessel 10 is connected to a trap section 18 via a back pressure regulator 17, and a gas meter 19 is provided downstream of the trap section 18.

[0017] The cylinder 12 contains carbon dioxide and supplies the carbon dioxide to the extraction vessel 10 .

[0018] The pump 13 is equipped with a liquid pressure delivery pump and a cooler. The liquid pressure delivery pump is an HPLC pump (a pump for high performance liquid chromatography) or the like. The pump 13 pressurizes and delivers the carbon dioxide contained in the cylinder 12. The cooler attached to the pump 13 cools the carbon dioxide when the circulating carbon dioxide is adiabatically compressed.

[0019] Pressure gauge 14 measures the pressure of the carbon dioxide supplied to extraction vessel 10.

[0020] Thermocouple 15 measures the temperature of the carbon dioxide supplied to extraction vessel 10.

[0021] Carbon dioxide supplied from cylinder 12 is pressurized by pump 13, the pressure is checked by pressure gauge 14, and the temperature is checked by thermocouple 15, and the carbon dioxide is introduced into extraction vessel 10 at a predetermined flow rate while the pressure and temperature are controlled.

[0022] The container 16 is made of, for example, stainless steel, and contains water. The carbon dioxide supplied from the cylinder 12 is hydrated by contacting with the water in the container 16, and the hydrated carbon dioxide is supplied to the extraction container 10. The carbon dioxide may be saturated with 1 to 3% by weight of water, and carbon dioxide saturated with water may be supplied. When no water is contained in the container 16, dry carbon dioxide not containing water is supplied to the extraction container 10.

[0023] The extraction vessel 10 is a pressure-resistant hollow vessel made of, for example, stainless steel, and can maintain a high pressure of, for example, 46 MPa or less. The extraction vessel 10 contains unroasted coffee beans from which caffeine is to be removed. The unroasted coffee beans from which caffeine is to be removed are those moistened with water before the caffeine removal process.

[0024] The type of unroasted coffee beans to be de-caffeinated can be preferably Arabica, such as Bourbon, Caturra, Mundo Novo, Catuai, Typica, Sumatra, Mocha, Blue Mountain, etc. There is no particular limitation on the type of unroasted coffee beans that can be applied, and the method can also be applied to Arabica, Robusta, and hybrids other than those mentioned above. There is also no particular limitation on the origin of the coffee beans.

[0025] The back pressure regulator 17 is provided at the outlet of the extraction vessel 10 and adjusts the pressure inside the extraction vessel 10. With unroasted coffee beans from which caffeine is to be removed housed in the extraction vessel 10, hydrous carbon dioxide is introduced from the inlet of the extraction vessel 10, and the carbon dioxide is brought to a supercritical state by pressurization, whereby caffeine is extracted and removed from the unroasted coffee beans using the hydrous supercritical carbon dioxide.

[0026] The trap unit 18 is connected to the outlet of the extraction vessel 10 via a back pressure regulator 17. The trap unit 18 is adapted to receive the carbon dioxide extracted in the extraction vessel 10, and to cool the carbon dioxide to a predetermined temperature to solidify and capture the components dissolved in the carbon dioxide. The trap unit 18 may have a configuration in which a plurality of traps, such as a first trap 18a and a second trap 18b, are connected in series or in parallel. In FIG. 1, the trap unit 18 has a configuration in which the first trap 18a and the second trap 18b are connected in series. The first trap 18a and the second trap 18b may be cooled at different temperatures, for example. The solidified components captured by the trap unit 18 are separately collected and used for analysis or other purposes.

[0027] The gas meter 19 is provided downstream of the trap unit 18 and measures the flow rate and total flow rate of the carbon dioxide guided through the trap unit 18 .

[0028] (How to remove decaffeine from unroasted coffee beans) In the method for removing decaffeine from unroasted coffee beans of this embodiment, first, the unroasted coffee beans are brought into contact with water to be moistened. The moistening conditions are not particularly limited. For example, the unroasted coffee beans are brought into contact with water at 30° C. or higher and 90° C. or lower to be moistened. The temperature of the water brought into contact with the unroasted coffee beans is preferably 40° C. or higher and 80° C. or lower. The weight of water contained in the unroasted coffee beans relative to the dry weight of the unroasted coffee beans (moisture content) is preferably 25% or higher and 50% or lower, more preferably 35% or higher and 40% or lower. The weight of water brought into contact with the unroasted coffee beans relative to the dry weight of the unroasted coffee beans is preferably 30% or higher and 100% or lower, more preferably 40% or higher and 60% or lower. The time for which the unroasted coffee beans are brought into contact with water to be moistened is preferably 3 hours or higher and 24 hours or lower.

[0029] In the method for removing decaffeine from unroasted coffee beans of this embodiment, the steps subsequent to the wetting step are carried out using the extraction apparatus 1. The unroasted coffee beans moistened as described above are placed in the extraction container 10. There is no limitation on the amount of unroasted coffee beans to be placed, but for example, they are placed as densely as possible in the extraction container 10, specifically, an amount of 4.5 g.

[0030] Next, the carbon dioxide is brought into contact with water to obtain hydrated carbon dioxide. Carbon dioxide can be brought into contact with water by supplying carbon dioxide from the cylinder 12 to a container 16 containing water. As a result, hydrated carbon dioxide is obtained. In this embodiment, unless otherwise specified, hydrated carbon dioxide is used. In the experimental examples described later, hydrated carbon dioxide and non-hydrated carbon dioxide are used, and the presence or absence of hydration is distinguished.

[0031] Aqueous carbon dioxide is then introduced into the extraction vessel 10 and contacted with the moistened green coffee beans.

[0032] Here, the water-containing carbon dioxide is brought to a supercritical state by pressurization, and the water-containing carbon dioxide is brought to a non-supercritical state by depressurization, and the cycle of pressurization and depressurization is repeated multiple times. In this manner, caffeine is extracted and removed from the unroasted coffee beans. By making the carbon dioxide water-containing, it is possible to prevent the unroasted coffee beans from drying out when the caffeine is extracted with carbon dioxide.

[0033] FIG. 2 is a diagram for explaining pressure changes in the extraction method using supercritical carbon dioxide according to this embodiment, with the vertical axis indicating pressure P and the horizontal axis indicating time t. FIG. 2(A) shows pressure changes during continuous extraction in which pressure is increased to a predetermined pressure, the pressure is maintained for a predetermined period, and then pressure is reduced. FIG. 2(A) corresponds to a conventional method in contrast to this embodiment. For example, pressure is increased to a predetermined pressure during period T1, the predetermined pressure is maintained during period T2, and pressure is reduced during period T3.

[0034] FIG. 2(B) shows the pressure change in the extraction method using supercritical carbon dioxide of this embodiment. In period T11, pressure is increased to a predetermined pressure, the predetermined pressure is maintained in period T12, and depressurization is performed in period T13. Then, pressure is increased to a predetermined pressure in period T21, the predetermined pressure is maintained in period T22, and depressurization is performed in period T23. Then, pressure is increased to a predetermined pressure in period T31, the predetermined pressure is maintained in period T32, and depressurization is performed in period T33. In this way, the cycle of pressurization, pressure maintenance, and depressurization is repeated multiple times. Extraction performed when the cycle of pressurization, pressure maintenance, and depressurization is repeated multiple times is called pressure fluctuation extraction. FIG. 2(B) shows that the above cycle is repeated three times. There is no particular limitation on the number of cycles, and for example, the cycle can be repeated from 2 to 11 times.

[0035] In addition, in FIG. 2(B), after period T33, pressure is increased to a predetermined pressure in period T41, and then the pressure is maintained in period T42 to terminate the extraction operation. However, as in Experimental Example 11 described later, when performing extraction, the period T42 in which the predetermined pressure is maintained may not be provided, and pressure fluctuation extraction may be performed continuously until the end by repeating cycles of pressurization, pressure maintenance, and depressurization.

[0036] In the above cycle, the length of the periods T12, T22, and T32 during which a constant pressure is maintained after the carbon dioxide has been brought to a supercritical state by pressurization and before depressurization begins so that the carbon dioxide is no longer in a supercritical state, is 10 minutes or more and 30 minutes or less, preferably 30 minutes.

[0037] In the above cycle, the duration of periods T11, T21, and T31 during which the pressure is increased from a non-supercritical state to a predetermined pressure to bring carbon dioxide into a supercritical state is 5 minutes or more and 10 minutes or less.

[0038] In the above cycle, the duration of the periods T13, T23, and T33 during which the pressure is reduced from the supercritical state to a non-supercritical state is between 5 and 10 minutes. If the pressure reduction time exceeds 10 minutes, the expansion of the unroasted coffee beans will be reduced, and the improvement of caffeine extraction may not be expected.

[0039] When carbon dioxide is brought into a supercritical state by pressurization, it is pressurized to a pressure of 10 MPa or more, for example, a pressure of 10 MPa or more and 30 MPa or less.

[0040] When carbon dioxide is made non-supercritical by reducing the pressure, it is reduced to atmospheric pressure.

[0041] 2(B), after the pressure fluctuation extraction by the multiple cycles, the pressure is increased to a predetermined pressure in period T41, the predetermined pressure is maintained in period T42, and reduced pressure is performed in period T43. Period T42 is longer than periods T12, T22, and T32 during which the pressure is maintained in the above cycles, and corresponds to continuous extraction performed after the pressure fluctuation extraction by the multiple cycles.

[0042] In the continuous extraction of Figure 2 (B) above, the length of the period T42 during which a constant pressure is maintained after carbon dioxide is brought to a supercritical state by pressurization until decompression is started so that the carbon dioxide is no longer in a supercritical state is 90 minutes or more and 150 minutes or less.

[0043] In the continuous extraction of Figure 2 (B), the period T41 in which the pressure is increased from a non-supercritical state to a predetermined pressure to bring the carbon dioxide into a supercritical state, the period T43 in which the pressure is reduced from the supercritical state to a non-supercritical state, the pressure when the carbon dioxide is brought into a supercritical state by pressurization, and the pressure when the carbon dioxide is brought into a non-supercritical state by reduced pressure are the same as the corresponding periods and pressures in the above-mentioned pressure fluctuation extraction cycle.

[0044] The temperature when the above-mentioned supercritical carbon dioxide is used to extract and remove caffeine from unroasted coffee beans is, for example, from 40° C. to 80° C., specifically, 80° C. The temperature can be adjusted by the set temperature of the oven 11.

[0045] By the above-mentioned extraction and removal of caffeine, the caffeine is removed so that the caffeine content in the coffee beans when dried is 0.3% or less of the total weight, or so that the caffeine content in the coffee beans is less than 30% of the initial content (content before decaffeination).

[0046] When caffeine is extracted and removed from unroasted coffee beans using the above-mentioned supercritical carbon dioxide, the carbon dioxide that contributed to the extraction and removal of caffeine inside the extraction vessel 10 is led to the outside of the extraction vessel 10 while maintaining the pressure at the stage of maintaining the pressure inside the extraction vessel 10 through the back pressure regulator 17, or while reducing the pressure at the stage of reducing the pressure inside the extraction vessel 10, and is led to the trap section 18. The components contained in the unroasted coffee beans, such as caffeine dissolved in the carbon dioxide, are captured by the trap section 18. The flow rate and total flow rate of the carbon dioxide that has passed through the trap section 18 are measured by a gas meter 19 provided downstream of the trap section 18, and the carbon dioxide is released into the atmosphere. For stable operation of the device, it is preferable not to reuse the carbon dioxide by circulating it. In addition, if carbon dioxide is circulated and reused, the device becomes complicated and the cost of the device increases, but by not circulating it, the device configuration is simple and inexpensive.

[0047] After the decaffeination process, the moist unroasted coffee beans are dried. For example, the moist unroasted coffee beans are dried in an oven, with hot air from a heater, or by drying in the sun. The moisture content is controlled to be 6% to 18%, preferably 10% to 15%, after the drying process.

[0048] The decaffeinated unroasted coffee beans obtained as described above are roasted to a desired roasting level. The roasted coffee beans obtained are ground in a coffee mill or the like, and extracted by drip or the like to make coffee.

[0049] <Action and Effects> As described above, by using hydrated carbon dioxide, pressurizing the carbon dioxide to a supercritical state, depressurizing the carbon dioxide to a non-supercritical state, and repeating the cycle of pressurization and depressurization multiple times, caffeine can be efficiently removed while suppressing the removal of lipids. In this way, the deterioration of the original taste of the coffee beans caused by the removal of lipids, etc. can be suppressed, and caffeine can be extracted and removed from unroasted coffee beans.

[0050] <Verification experiment> (Verification experiment 1) Unroasted Arabica coffee beans were prepared and soaked in water at 80° C. for 1 hour to prepare moistened unroasted coffee beans with a moisture content of 40%. The obtained moistened unroasted coffee beans were subjected to extraction and removal of caffeine using supercritical carbon dioxide as described below, using the extraction apparatus 1 shown in FIG.

[0051] (Experimental Example 1) In Experimental Example 1, pressure fluctuation extraction was performed by repeating three cycles of pressurization, pressure retention, and decompression according to the pressure change shown in FIG. 2(B). Carbon dioxide containing water was used. In the above cycle, the pressure for the supercritical state was 30 MPa, the pressure released to make the carbon dioxide non-supercritical was atmospheric pressure, the length of the periods T11, T21, and T31 in which the carbon dioxide non-supercritical state was increased to a predetermined pressure by pressurization to make the carbon dioxide supercritical was 10 minutes, the length of the periods T12, T22, and T32 in which a constant pressure was maintained after the carbon dioxide was made supercritical by pressurization until decompression was started so that the carbon dioxide was no longer in a supercritical state was 30 minutes, and the length of the periods T13, T23, and T33 in which the carbon dioxide non-supercritical state was made non-supercritical by decompression was 10 minutes. The flow rate of carbon dioxide in each cycle was 2 mL / min. After the above three cycles of pressure fluctuation extraction, continuous extraction was performed with the same pressure as the pressure in each cycle. The flow rate of carbon dioxide during the continuous extraction was 2 mL / min. Caffeine was extracted and removed as described above.

[0052] (Experimental Example 2) In Experimental Example 2, continuous extraction was performed according to the pressure change shown in FIG. 2(A). Carbon dioxide containing water was used. In the above continuous extraction, the pressure for making the carbon dioxide supercritical was 30 MPa, the pressure released to make the carbon dioxide non-supercritical was atmospheric pressure, the length of the period T1 during which the carbon dioxide was made supercritical by increasing the pressure from a non-supercritical state to a predetermined pressure by pressurization was 10 minutes, and the length of the period T3 during which the carbon dioxide was made non-supercritical by reducing the pressure from the supercritical state was 10 minutes. The flow rate of carbon dioxide in the continuous extraction was 2 mL / min. As described above, caffeine was extracted and removed.

[0053] (Experimental Example 3) Caffeine was extracted and removed in the same manner as in Experimental Example 1, except that the pressure for creating a supercritical state in the cycle was 20 MPa.

[0054] (Experimental Example 4) Caffeine was extracted and removed in the same manner as in Experimental Example 2, except that the pressure for creating a supercritical state in the cycle was 20 MPa.

[0055] (Experimental Example 5) Caffeine was extracted and removed in the same manner as in Experimental Example 1, except that the pressure for creating a supercritical state in the cycle was 10 MPa.

[0056] (Experimental Example 6) Caffeine was extracted and removed in the same manner as in Experimental Example 2, except that the pressure for creating a supercritical state in the cycle was 10 MPa.

[0057] In the above experimental examples 1 to 6, the caffeine extraction rate (Caffeine extraction rate [%]) relative to the mass of carbon dioxide per unit mass of dried unroasted coffee beans ((Mass of CO2 [g]) / (Bean (Dry) [g])) was investigated based on the analysis of the material captured in trap section 18 and the carbon dioxide used.

[0058] Sample collection in the trap portion 18 was performed after the pressure was reduced in the three cycles of pressure fluctuation extraction, and when 15 L of carbon dioxide was used in the continuous extraction.

[0059] The analysis of the samples captured in the trap section 18 was performed by high performance liquid chromatography (HPLC) after diluting each sample with 20 mL of water and subjecting it to ultrasonic treatment at 40° C. for 2 hours. The HPLC measurement conditions were as follows: a column (Shin-pack VP-ODS) was used in an HPLC device (Hewlett Packard 1100), the flow rate was 1.0 mL / min with a pump, detection was performed by UV (273 nm), and the mobile phase was (0.1 vol% formic acid / acetonitrile = 85 / 15).

[0060] The caffeine extraction rate (% ) was calculated using the formula: 100 × (mass [g] of caffeine recovered in trap 18) / (mass [g] of dried unroasted coffee beans × 0.01).

[0061] Figure 3 is a graph showing the caffeine extraction rate versus the amount of carbon dioxide in verification experiment 1. The horizontal axis is the mass of carbon dioxide per unit mass of dry unroasted coffee beans ((Mass of CO2 [g]) / (Bean (Dry) [g])), and the vertical axis is the caffeine extraction rate (Caffeine extraction rate [%]).

[0062] 3(A) shows the results of Experimental Example 1 and Experimental Example 2 together, with a showing Experimental Example 1 and b showing Experimental Example 2. According to the pressure fluctuation extraction of Experimental Example 1, a higher caffeine extraction rate per carbon dioxide mass was obtained compared to the continuous extraction of Experimental Example 2.

[0063] 3(B) shows the results of Experimental Example 3 and Experimental Example 4 together, with c showing Experimental Example 3 and d showing Experimental Example 4. According to the pressure fluctuation extraction of Experimental Example 3, a higher caffeine extraction rate per carbon dioxide mass was obtained compared to the continuous extraction of Experimental Example 4.

[0064] 3(C) shows the results of Experimental Example 5 and Experimental Example 6 together, with e showing Experimental Example 5 and f showing Experimental Example 6. According to the pressure fluctuation extraction of Experimental Example 5, a higher caffeine extraction rate per carbon dioxide mass was obtained compared to the continuous extraction of Experimental Example 6.

[0065] (Verification experiment 2) (Experimental Example 7) In Experimental Example 7, continuous extraction was performed according to the pressure change shown in Figure 2 (A). Carbon dioxide not containing water was used. In the above continuous extraction, the pressure for the supercritical state was set to 30 MPa. Except for the above, caffeine was extracted and removed in the same manner as in Experimental Example 2.

[0066] (Experimental Example 8) In Experimental Example 8, pressure fluctuation extraction was performed by repeating three cycles according to the pressure change shown in Figure 2 (B). Carbon dioxide not containing water was used. In the above cycle, the pressure for the supercritical state was set to 30 MPa. Except for the above, caffeine was extracted and removed in the same manner as in Experimental Example 1.

[0067] In the above Experimental Examples 7 to 8, the caffeine extraction rate (Caffeine extraction rate [%]) relative to the mass of carbon dioxide per unit mass of dried unroasted coffee beans ((Mass of CO2 [g]) / (Bean (Dry) [g])) was investigated in the same manner as in Experimental Examples 1 to 6.

[0068] Figure 4 is a graph showing the caffeine extraction rate versus the amount of carbon dioxide in verification experiment 2. The horizontal axis is the mass of carbon dioxide per unit mass of dry unroasted coffee beans ((Mass of CO2 [g]) / (Bean (Dry) [g])), and the vertical axis is the caffeine extraction rate (Caffeine extraction rate [%]).

[0069] 4(A) shows the results of Experimental Example 2 and Experimental Example 7 together, with b showing Experimental Example 2 and g showing Experimental Example 7. According to the extraction using water-containing carbon dioxide in Experimental Example 2, a higher caffeine extraction rate per mass of carbon dioxide was obtained compared to the extraction using non-water-containing carbon dioxide in Experimental Example 7.

[0070] 4(B) shows the results of Experimental Example 1 and Experimental Example 8 together, with a showing Experimental Example 1 and h showing Experimental Example 8. According to the extraction using water-containing carbon dioxide in Experimental Example 1, a higher caffeine extraction rate per mass of carbon dioxide was obtained compared to the extraction using non-water-containing carbon dioxide in Experimental Example 8.

[0071] In the above experimental examples 1, 2, 7, and 8, the amount of lipid collected was determined from the analysis of the sample captured in the trap section 18, and the amount of lipid flowing out per unit mass 1 g of the unroasted coffee beans used for extraction was calculated. In experimental example 1, the total amount of lipid collected in the trap section 18 was 0.70 mg, and the amount of lipid flowing out per unit mass of the unroasted coffee beans was 0.29 mg. In experimental example 2, the total amount of lipid collected in the trap section 18 was 1.96 mg, and the amount of lipid flowing out per unit mass of the unroasted coffee beans was 0.80 mg. In experimental example 7, the total amount of lipid collected in the trap section 18 was 10.12 mg, and the amount of lipid flowing out per unit mass of the unroasted coffee beans was 4.21 mg. In experimental example 8, the total amount of lipid collected in the trap section 18 was 15.77 mg, and the amount of lipid flowing out per unit mass of the unroasted coffee beans was 6.2 mg.

[0072] From a comparison of Experimental Example 2 and Experimental Example 7, it was confirmed that the use of hydrated carbon dioxide can suppress the removal of lipids in the extraction and removal of caffeine. In the lipid analysis described above, oleic acid was recovered as lipids in Experimental Example 7, but oleic acid was not detected in Experimental Example 2, which used hydrated carbon dioxide.

[0073] From a comparison of Experimental Example 1 and Experimental Example 8, it was confirmed that the use of hydrated carbon dioxide can suppress the removal of lipids in the extraction and removal of caffeine. In the lipid analysis described above, oleic acid was recovered as lipids in Experimental Example 8, but oleic acid was not detected in Experimental Example 1, which used hydrated carbon dioxide.

[0074] From a comparison between Experimental Example 1 and Experimental Example 2, it was confirmed that the removal of lipids can be suppressed during the extraction and removal of caffeine by performing pressure fluctuation extraction.

[0075] (Verification experiment 3) (Experimental Example 9) In Experimental Example 9, the lengths of the periods T13, T23, and T33 during which the supercritical state was reduced in pressure to a non-supercritical state were 5 minutes. Except for the above, the same procedure as in Experimental Example 1 was used to extract and remove caffeine.

[0076] In the above Experimental Example 9, similarly to Experimental Examples 1 to 6, the caffeine extraction rate (Caffeine extraction rate [%]) relative to the mass of carbon dioxide per unit mass of dried unroasted coffee beans ((Mass of CO2 [g]) / (Bean (Dry) [g])) was investigated.

[0077] FIG. 5 is a graph showing the caffeine extraction rate relative to the amount of carbon dioxide in verification experiment 3. The horizontal axis is the mass of carbon dioxide per unit mass of dried unroasted coffee beans ((Mass of CO2 [g]) / (Bean (Dry) [g])), and the vertical axis is the caffeine extraction rate (Caffeine extraction rate [%]). In FIG. 5, a indicates Experimental Example 1, and i indicates Experimental Example 9. By extracting in Experimental Example 9 in which the period during which the critical state was reduced to a non-supercritical state by reducing pressure was set to 5 minutes, a high caffeine extraction rate relative to the amount of carbon dioxide was obtained, similar to Experimental Example 1.

[0078] (Verification experiment 4) (Experimental Example 10) In Experimental Example 10, pressure fluctuation extraction was performed by repeating three cycles according to the pressure change shown in Figure 2 (B). Carbon dioxide containing water was used. In the above cycle, the periods T12, T22, and T32 during which the pressure was kept constant after the carbon dioxide was made supercritical by pressurization until the pressure reduction was started so that the carbon dioxide was no longer in a supercritical state were set to zero. Except for the above, the extraction and removal of caffeine was performed in the same manner as in Experimental Example 1.

[0079] In the above Experimental Example 10, similarly to Experimental Examples 1 to 6, the caffeine extraction rate (Caffeine extraction rate [%]) relative to the mass of carbon dioxide per unit mass of dried unroasted coffee beans ((Mass of CO2 [g]) / (Bean (Dry) [g])) was investigated.

[0080] FIG. 6 is a graph showing the caffeine extraction rate versus the amount of carbon dioxide in verification experiment 4. The horizontal axis is the mass of carbon dioxide per unit mass of dry unroasted coffee beans ((Mass of CO2 [g]) / (Bean (Dry) [g])), and the vertical axis is the caffeine extraction rate (Caffeine extraction rate [%]). FIG. 6 shows the results of Experimental Example 1, Experimental Example 2, and Experimental Example 10 together, with a showing Experimental Example 1, b showing Experimental Example 2, and j showing Experimental Example 10. According to the extraction in which the period from when carbon dioxide was made supercritical by pressurization in Experimental Example 10 until the start of decompression so that carbon dioxide was no longer in a supercritical state was set to zero, the behavior was almost the same as that of the continuous extraction in Experimental Example 2, and the effect of increasing the caffeine extraction rate was small.

[0081] (Verification experiment 5) (Experimental Example 11) In Experimental Example 11, the cycle of pressurization, pressure retention, and depressurization (pressure fluctuation extraction) was repeated to the end according to the pressure changes shown in Figure 2 (B) in Experimental Example 1, and extraction operation was performed without continuous extraction. The cycle was repeated 11 times to perform pressure fluctuation extraction. The pressurization period, constant pressure retention period, and depressurization period from the third time onwards were 10 minutes, 30 minutes, and 10 minutes, respectively, as in the first three times. After the 11 cycles of pressure fluctuation extraction, continuous extraction was not performed, and the extraction operation was terminated. In the above manner, caffeine was extracted and removed.

[0082] FIG. 7 is a graph showing the caffeine extraction rate versus the amount of carbon dioxide in verification experiment 5. The horizontal axis is the mass of carbon dioxide per unit mass of dry unroasted coffee beans ((Mass of CO2 [g]) / (Bean (Dry) [g])), and the vertical axis is the caffeine extraction rate (Caffeine extraction rate [%]). FIG. 7 shows the results of Experimental Example 1, Experimental Example 2, and Experimental Example 11 together, with a showing Experimental Example 1, b showing Experimental Example 2, and k showing Experimental Example 11. As shown in FIG. 7, in Experimental Example 11, the amount of caffeine removed increases each time pressure fluctuation extraction is performed. The amount of caffeine extracted in Experimental Example 11 exceeds that in Experimental Example 1, and it is possible that more caffeine can be removed.

[0083] (Verification experiment 6) FIG. 8 is an optical microscope photograph of the cross section of unroasted coffee beans in verification experiment 6. FIG. 8(A) shows unroasted coffee beans that have not been subjected to hydration treatment and caffeine extraction and removal treatment, FIG. 8(B) shows unroasted coffee beans that have been subjected to hydration treatment in Experimental Example 2 followed by extraction and removal treatment by continuous caffeine extraction, and FIG. 8(C) shows unroasted coffee beans that have been subjected to hydration treatment in Experimental Example 1 followed by extraction and removal treatment by pressure fluctuation extraction of caffeine (at the time when three pressure fluctuations were completed). Both FIG. 8(B) and FIG. 8(C) were taken under the same conditions of 30 L of carbon dioxide usage. Each unroasted coffee bean sample was embedded in 4% CMC (sodium carboxymethylcellulose) and frozen, then placed in a cryostat (CM1950, Leica) to prepare slices with a thickness of 15 micrometers. The prepared slices were collected on cryofilm and dried at room temperature in a tube containing silica gel. They were attached to a slide glass using conductive tape and used for measurement. For the measurements, images were taken using an optical microscope attached to an imaging mass microscope (iMScope QT).

[0084] As shown in Figure 8(A), a smooth surface was observed in unroasted coffee beans that had not been subjected to a moisture-containing treatment or a caffeine extraction and removal treatment. Enlarged and deformed cells were observed in unroasted coffee beans that had been subjected to a moisture-containing treatment followed by a caffeine extraction and removal treatment by continuous extraction as shown in Figure 8(B) and in unroasted coffee beans that had been subjected to a moisture-containing treatment followed by a caffeine extraction and removal treatment by pressure fluctuation extraction as shown in Figure 8(C). The degree of cell enlargement was greater in the unroasted coffee beans that had been subjected to a pressure fluctuation extraction and removal treatment as shown in Figure 8(C), but it was confirmed that the cells were not destroyed.

[0085] FIG. 9 is an explanatory diagram for explaining the movement of carbon dioxide and caffeine in a method for removing caffeine from unroasted coffee beans. FIG. 9 explains a case where hydrated carbon dioxide is used. By hydrating the carbon dioxide, it is possible to prevent the unroasted coffee beans from drying out when caffeine is extracted with carbon dioxide. FIGS. 9(A) to (C) show the shape of the coffee bean tissue and the presence of caffeine in this embodiment. FIG. 9(A) shows the stage where carbon dioxide is brought to a supercritical state by pressurization in extraction including pressure fluctuation extraction, and shows how the outer periphery of coffee bean tissue 20 having pores 20a due to a cellular structure therein is filled with supercritical carbon dioxide 22. At this stage, supercritical carbon dioxide 22 has not yet reached caffeine 21 present inside coffee bean tissue 20.

[0086] 9(B) shows the stage where the carbon dioxide is kept at a constant pressure in a supercritical state by pressurization, and shows that a portion 23 of the supercritical carbon dioxide 22 has entered the pores 20a of the coffee bean tissue 20 and reached the position where the caffeine 21 is present. The supercritical carbon dioxide 22 that has reached the caffeine 21 dissolves the caffeine 21.

[0087] 9(C) shows a stage in which the supercritical state is changed to a non-supercritical state by reducing the pressure, in which the carbon dioxide having dissolved caffeine 21 expands due to the reduced pressure, and the passing speed through pores 20a instantaneously increases, generating a flow 24 of carbon dioxide to the outside of coffee bean tissue 20. At this stage, the carbon dioxide having dissolved caffeine 21 moves to the outside of coffee bean tissue 20. It is believed that the flow 24 of carbon dioxide to the outside of coffee bean tissue 20, which has an increased passing speed, physically expands pores 20a of coffee bean tissue 20. As described above, the method for removing caffeine from unroasted coffee beans using pressure fluctuation extraction of this embodiment has the advantage of less wasted carbon dioxide compared to the conventional method described below, and it is believed that the movement speed of caffeine increases, increasing the caffeine extraction rate.

[0088] Fig. 9(D) shows the movement of carbon dioxide and caffeine in coffee beans in continuous extraction according to the conventional method. Fig. 9(D) shows the case where the flow rate of carbon dioxide is increased in continuous extraction. A high flow rate of supercritical carbon dioxide 25 flows around the outer periphery of coffee bean tissue 20, and some 26 enters pores 20a, reaches and dissolves caffeine 21 located inside coffee bean tissue 20, and becomes flow 27 to the outside of coffee bean tissue 20, reaching from the inside to the outside. Most of the carbon dioxide flows outside coffee bean tissue 20 and does not contribute to the removal of caffeine, and a large amount of carbon dioxide is wasted.

[0089] Figure 9(E) shows the movement of carbon dioxide and caffeine in coffee beans in continuous extraction according to the conventional method, in the case of a lower flow rate than in the case of Figure 9(D). Supercritical carbon dioxide 28 flows at a low flow rate around the outer periphery of coffee bean tissue 20, and some of the supercritical carbon dioxide 28 enters pores 20a, reaches and dissolves caffeine 21 located inside coffee bean tissue 20, and becomes flow 29 to the outside of coffee bean tissue 20, reaching from the inside to the outside. Little carbon dioxide is wasted, but the movement speed of caffeine is slow, making it difficult to increase the caffeine extraction rate.

[0090] The present invention is not limited to the above embodiment. For example, it can be applied to a method for extracting and removing caffeine from caffeine-containing materials other than unroasted coffee beans. In the embodiment, the removal of lipids is reduced so as not to impair the original taste of the coffee beans, but it may also be configured to suppress the removal of components other than lipids that may contribute to the original taste of the coffee beans, such as sugars and acids. Although supercritical carbon dioxide is used for caffeine extraction, other supercritical fluids can be used instead of supercritical carbon dioxide. [Explanation of symbols]

[0091] 1 Extraction device 10 Extraction vessel 11. Oven 12 Cylinder 13. Pump 14 Pressure gauge 15 Thermocouple 16 Container 17 Backpressure Regulator 18 Trap section 18a First Trap 18b 2nd trap 19 Gas meter

Claims

1. Wetting the unroasted coffee beans by contacting them with water; The moistened unroasted coffee beans are placed in an extraction vessel; contacting the carbon dioxide with water to obtain hydrated carbon dioxide; The water-containing carbon dioxide is introduced into the extraction vessel and brought into contact with the wetted unroasted coffee beans, the carbon dioxide is brought into a supercritical state by pressurization, and the carbon dioxide is brought into a non-supercritical state by depressurization, and the cycle of pressurization and depressurization is repeated multiple times to extract and remove caffeine from the unroasted coffee beans. How to decaffeine unroasted coffee beans.

2. After repeating the cycle of pressurization and depressurization multiple times, the carbon dioxide is brought into a supercritical state by pressurization, and a constant pressure is maintained for 90 minutes to 150 minutes, thereby continuously extracting and removing caffeine from the unroasted coffee beans. The method for removing caffeine from unroasted coffee beans according to claim 1.

3. In the cycle of pressurization and depressurization, after the carbon dioxide is brought to the supercritical state by the pressurization, a constant pressure is maintained for 10 minutes or more and 30 minutes or less until the depressurization is started so that the carbon dioxide is no longer in the supercritical state. The method for removing caffeine from unroasted coffee beans according to claim 1.

4. When the carbon dioxide is put into a state other than the supercritical state by the decompression, the decompression is performed within a period of 5 minutes or more and 10 minutes or less. The method for removing caffeine from unroasted coffee beans according to claim 1.

5. When the carbon dioxide is brought into the supercritical state by the pressurization, the carbon dioxide is pressurized to a pressure of 10 MPa or more. The method for removing caffeine from unroasted coffee beans according to claim 1.

6. When the carbon dioxide is reduced in pressure to a state other than the supercritical state, the pressure is reduced to atmospheric pressure. The method for removing caffeine from unroasted coffee beans according to claim 1.

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