Method for producing tea extract

Abstract

To provide a method for efficiently extracting R1-barrigenol from tea, without use of large quantities of organic solvents.SOLUTION: A method for preparing R1-barrigenol includes the following steps: (1) extracting a crushed tea material with an aqueous solution of alkali metal hydroxide or an aqueous alcohol solution containing alkali metal hydroxide; (2) subjecting the extract obtained in the step (1) to acid hydrolysis and alkali hydrolysis. A content of alkali metal hydroxide in the aqueous solution of alkali metal hydroxide or the aqueous alcohol solution containing alkali metal hydroxide ranges from 0.05 to 2.5 mass%. An alcohol content in the aqueous alcohol solution containing alkali metal hydroxide is 50 vol.% or less. The alcohol is a C1-3 lower alcohol.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a tea extract containing R1-valigenol.

Background Art

[0002] R1-valigenol is one of the aglycones of saponins contained in tea, and is known to exhibit antibacterial activity (Non-Patent Document 1) and oxytocin receptor activation action (Patent Document 1). R1-valigenol can be obtained through two steps of extraction and decomposition from tea. In the extraction step, saponins are extracted from tea with an organic solvent such as ethanol or methanol. In the next decomposition step, R1-valigenol is obtained by removing sugar from the extract containing saponins with an acid and removing functional groups such as acyl groups with an alkali. For example, Non-Patent Document 2 discloses that tea saponin was prepared from tea leaves with 97% methanol and then R1-valigenol was obtained by acid-alkali decomposition. As another method for obtaining the aglycone of saponin from plants, for example, Patent Document 2 describes that extraction is carried out from sweet potato at 60 to 100 °C using water or aqueous ethanol as a solvent, and the water content of the aqueous ethanol used as the extraction solvent is set to 5 to 50%. In the extraction steps of these methods, since a large amount of organic solvent is used, the cost is high and it cannot be said to be an industrially efficient method. Therefore, it is desired to reduce the ratio of the organic solvent used in the extraction step, but when the ratio of the organic solvent is reduced, the extraction efficiency decreases. In particular, when the ethanol ratio of the solvent in the extraction step is 40% or less, there is a problem that the extraction efficiency greatly decreases. Incidentally, attempts have been made to use alkali metal hydroxides to improve extraction efficiency when producing extracts from plants. For example, Patent Document 3 describes that when extracting triterpene compounds from olive plant pulverized material, adding 0.05 to 0.2 M alkali metal hydroxide to a 30 to 60% lower alcohol aqueous solution, which is the extraction solvent, improves the extraction efficiency. Patent Document 4 discloses that when extracting saponins from plants of the genus Bupleurum using 40% or more methanol as the extraction solvent, the extraction is carried out under alkaline conditions. It is stated that extraction under alkaline conditions can prevent the denaturation of saponins by organic acids released from the plant. Patent Document 5 discloses a method for extracting saponins from red ginseng with alkaline ionized water at pH 10 to 12. It is stated that this method removes non-saponin components to the maximum extent possible, and high-purity saponins can be obtained. Patent Document 6 discloses a method for obtaining beet saponins by extracting sugar beet pulverized material with an alkaline aqueous solution. It is stated that extraction with an alkaline aqueous solution can prevent beet saponins from being converted to aglycones. However, although these methods are useful in the production of each plant extract, it is known that catechins contained in tea are unstable and decompose under alkaline conditions (Non-Patent Document 3), and it is common to extract extracts from tea under acidic conditions (Patent Documents 7 and 8). Furthermore, it is known that the extraction efficiency of saponins from soybeans decreases under alkaline conditions (Patent Document 9). For these reasons, no attempts have been made to use alkali metal hydroxides to improve the extraction efficiency in the extraction process when obtaining R1-valigenol from tea. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-072837 [Patent Document 2] Japanese Patent Publication No. 2015-151344 [Patent Document 3] Japanese Patent Publication No. 2013-091604 [Patent Document 4] Japanese Patent Publication No. 6-206891 [Patent Document 5] Japanese Patent Publication No. 2016-098229 [Patent Document 6] Japanese Patent Publication No. 63-093794 [Patent Document 7] Special Publication 2020-533006 [Patent Document 8] Japanese Patent Publication No. 2017-73982 [Patent Document 9] WO2003 / 075939 [Non-patent literature]

[0004] [Non-Patent Document 1] Oh JH, et al. Molecules. 19(3):3607-3616, 2014 Published 2014 Mar 24. doi:10.3390 / molecules19033607 [Non-Patent Document 2] Noka Vol. 43, No. 11, p.750~757, 1969 [Non-Patent Document 3] Antioxidant effects of tea extracts and their effective use in the food industry (Monthly Food Chemical, June 2004 issue, pp. 29-34) [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a method for efficiently obtaining R1-valigenol from tea without using large amounts of organic solvents. [Means for solving the problem]

[0006] The inventors of the present invention have discovered that by using an aqueous solution of alkali metal hydroxide or an aqueous alcohol solution of alkali metal hydroxide with a predetermined alkali metal hydroxide content in the extraction process of ground tea, it is possible to efficiently obtain R1-valigenol from tea without using a large amount of organic solvent, thus completing the present invention. In other words, the present invention is as follows. [1] The following steps; (1) A step of extracting the ground tea material with an aqueous alkali metal hydroxide solution or an aqueous alkali metal hydroxide alcohol solution and (2) The extract obtained in step (1) is subjected to acid hydrolysis and alkaline hydrolysis, A method for preparing R1-valigenol, The alkali metal hydroxide content in the alkali metal hydroxide aqueous solution and the alkali metal hydroxide aqueous alcohol solution is 0.05 to 2.5% by mass. The alcohol content in the alkali metal hydroxide aqueous alcohol solution is 50% by volume or less. The method wherein the alcohol in step (1) is a lower alcohol having 1 to 3 carbon atoms. [2] The method according to [1], wherein the alkali metal hydroxide is sodium hydroxide or potassium hydroxide. [3] The method according to [1] or [2], wherein the lower alcohol having 1 to 3 carbon atoms is ethanol. [Effects of the Invention]

[0007] This invention makes it possible to efficiently obtain R1-valigenol from tea without using large amounts of organic solvents. [Modes for carrying out the invention]

[0008] The present invention relates to a method for preparing R1-barygenol, which includes the following steps: (1) a step of extracting a tea pulverized product with an aqueous alkali metal hydroxide solution or an aqueous alcohol solution containing an alkali metal hydroxide, and (2) a step of subjecting the extract obtained in step (1) to acid hydrolysis treatment and alkali hydrolysis treatment, wherein the content of the alkali metal hydroxide in the aqueous alkali metal hydroxide solution and the aqueous alcohol solution containing an alkali metal hydroxide is 0.05 to 2.5% by mass, the alcohol content in the aqueous alcohol solution containing an alkali metal hydroxide is 50% by volume or less, and the alcohol in step (1) is a lower alcohol having 1 to 3 carbon atoms.

[0009] In the present invention, R1-barygenol is an aglycone of saponin contained in tea. The tea is a plant Camellia sinensis of the genus Camellia in the family Theaceae, and the variety or origin of the tea is not particularly limited. In the present invention, the tea pulverized product refers to tea that has been appropriately pulverized finely. These include the extraction residues used for extracting tea beverages. The pulverization method and the degree of pulverization of the tea pulverized product are not limited. For example, dried tea is pulverized so as to pass through a mesh with an opening of 3 mm. Any part of the tea may be used as long as it contains R1-barygenol, such as flowers, leaves, stems, and roots. Preferably, it is a tea flower with a high content rate of R1-barygenol. These may be dried or not dried, and the pulverization method is not particularly limited.

[0010] The method of the present invention includes (1) a step of extracting a tea pulverized product with an aqueous alkali metal hydroxide solution or an aqueous alcohol solution containing an alkali metal hydroxide.

[0011] In the present invention, the alkali metal hydroxide in step (1) is preferably sodium hydroxide or potassium hydroxide, and more preferably sodium hydroxide. In the extraction step, the alkali metal hydroxide may be added to the pulverized tea together with water or hydrous alcohol in a solid state, or may be added to the pulverized tea as an aqueous solution of an alkali metal hydroxide or a hydrous alcohol solution of an alkali metal hydroxide. When adding the alkali metal hydroxide in a solid state, the order of adding the alkali metal hydroxide and water or hydrous alcohol is arbitrary and may be simultaneous. The amount of the alkali metal hydroxide is 0.05 to 2.5% by mass, preferably 0.1 to 2.0% by mass, and more preferably 0.15 to 1.5% by mass based on the total amount of water or hydrous alcohol. The alcohol is a lower alcohol having 1 to 3 carbon atoms, and preferably ethanol. The concentration of the alcohol is 50% by volume or less, preferably 45% by volume or less, and more preferably 40% by volume or less based on the total amount of the hydrous alcohol. Other organic solvents may be added within a range not impairing the effects of the present invention. The amount of water or hydrous alcohol to be used is preferably added in a range of 0.5 to 10 times, preferably 0.5 to 4 times (w / w) the mass of the dry pulverized tea. According to the present invention, it is advantageous that a low-concentration ethanol-containing aqueous solution is used as an extraction solvent, and by using an alkali metal hydroxide, the ethanol concentration of the extraction solvent can be lowered and R1-valigenol can be obtained with high efficiency.

[0012] In the method of the present invention, the extraction step can be carried out by a known method using the above extraction solvent. The above extraction solvent is added to the pulverized tea to be extracted, and preferably stirred, permeated or left standing at 60 to 100 ° C, more preferably 80 to 100 ° C, preferably for 1 to 8 hours, more preferably for 2 to 4 hours. Then, it is cooled to room temperature, and solid-liquid separation is carried out by filtration, centrifugation or the like, and the liquid part is recovered as an extract. The extract is neutralized by adding a neutralizing agent to adjust the pH to 6-8, preferably 6.5-7.5. Preferred neutralizing agents include sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, and formic acid, with hydrochloric acid being more preferable.

[0013] The method of the present invention includes (2) a step of treating the extract obtained in step (1) with acid hydrolysis and alkaline hydrolysis. The order in which the acid hydrolysis and alkaline hydrolysis treatments are performed does not matter.

[0014] (Acid hydrolysis treatment) In this invention, acid treatment is performed to convert saponins (glycosides) contained in tea to their aglycones. The conversion to aglycone proceeds by hydrolyzing the glycosidic bond between sapogenin and sugar with acid. After the extraction step or alkaline hydrolysis treatment, when hydrochloric acid is used as the acid, concentrated hydrochloric acid, alcohol, and water are added to the neutralized extract so that the final concentration is 3 to 9% by mass, preferably 6 to 9% by mass, and the alcohol concentration is 20 to 80% by volume, preferably 50 to 60% by volume. Next, the reaction is carried out at a temperature of preferably 60°C to 100°C, more preferably 70 to 80°C, for 30 minutes to 5 hours, more preferably 2 to 4 hours. The reaction is preferably carried out by reflux. Note that the acid is not limited to hydrochloric acid. For example, sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, formic acid, etc., may be used. The acid is added so that the pH of the reaction solution is 2 or less. The type of alcohol is not particularly limited, but is preferably an alcohol having 1 to 5 carbon atoms, and one or more alcohols selected from methanol, ethanol, isopropanol, propanol, and butanol may be used. More preferably, ethanol can be used as the alcohol. After the acid treatment described above, the solution is neutralized with an alkali. For neutralization, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, ammonia, etc., can be used. From the viewpoint of workability and cost, sodium hydroxide is preferred. These alkalis may be added in solid form or as aqueous solutions.

[0015] (Alkaline hydrolysis treatment) Alkaline treatment is performed to remove the acyl group from the saponin. Alkaline treatment proceeds by hydrolyzing the ester bond with alkali. After the extraction step or acid hydrolysis treatment, sodium hydroxide and alcohol are added to the neutralized extract, for example, sodium hydroxide is used as the alkaline substance, so that the final concentration is 1.5 to 5% by mass, preferably 1.5 to 3% by mass, and the ethanol concentration is 20 to 80% by volume, preferably 20 to 60% by volume. Next, the reaction is carried out at a temperature of preferably 60°C to 100°C, more preferably 70 to 80°C, for 30 minutes to 5 hours, more preferably 2 to 4 hours. The reaction is preferably carried out by reflux. Note that the alkaline substance is not limited to sodium hydroxide; for example, potassium hydroxide can be used. The alkaline substance is added so that the pH of the reaction solution is 13 or higher. The type of alcohol is not particularly limited, but preferably it is an alcohol having 1 to 5 carbon atoms, and one or more alcohols selected from methanol, ethanol, isopropanol, propanol, and butanol may be used. More preferably, ethanol can be used as the alcohol.

[0016] After acid hydrolysis or alkaline hydrolysis, salts are formed in the reaction solution by neutralization; therefore, it is preferable to remove these salts. Salt removal can be carried out by known methods. Typically, when the reaction solution is added to 20 times or more the volume of water and allowed to stand, R1-valigenol precipitates. A purified extract can be obtained by recovering the precipitate by filtration or centrifugation. [Examples]

[0017] Examples are shown below to illustrate the present invention in detail, but the present invention is not limited to the following examples.

[0018] Manufacturing Example 1: R from tea flowers 1 - Extraction of barigenol (conventional method) 1. (Extraction process) 10 g of crushed dried tea flowers were added to 100 ml of aqueous ethanol containing 60% ethanol by volume. After heating under reflux at 80°C for 2 hours, solids were removed by centrifugation and the crude extract was recovered. The volume of the liquid was measured to be 70 ml. 2. (Deglycoside deconjugation process by acid hydrolysis) 10 ml of crude extract was concentrated to dryness using an evaporator, and ethanol was dissolved in 50 ml of aqueous ethanol containing 60% by volume. Water and concentrated hydrochloric acid were added so that the final ethanol concentration was 50% by volume and the final hydrochloric acid concentration was 6% by mass. The mixture was heated under reflux at 70°C for 3 hours and neutralized with sodium hydroxide. 3. (Deacylation step by alkaline hydrolysis) Water and sodium hydroxide (solid) were added to the neutralized solution so that the final volume of ethanol was 50% by volume and the final concentration of sodium hydroxide was 1.7% by mass. The mixture was heated under reflux at 70°C for 1 hour and neutralized with hydrochloric acid to obtain a reaction solution containing R1-valigenol.

[0019] Manufacturing Example 2: R from tea flowers 1 - Extraction of barigenol (when alkali metal hydroxide is added to the extraction solvent in the conventional method) 1. (Extraction process) 10 g of crushed dried tea flowers were mixed with 100 ml of aqueous ethanol containing 60% ethanol by volume and 0.5 g of sodium hydroxide. After heating under reflux at 80°C for 2 hours, solids were removed by centrifugation and the crude extract was recovered. The crude extract was neutralized with hydrochloric acid and the volume was measured to be 70 ml. 2. (Deglycoside deconjugation process by acid hydrolysis) 10 ml of crude extract was concentrated to dryness using an evaporator, and ethanol was dissolved in 50 ml of aqueous ethanol containing 60% by volume. Water and concentrated hydrochloric acid were added so that the final ethanol concentration was 50% by volume and the final hydrochloric acid concentration was 6% by mass. The mixture was heated under reflux at 70°C for 3 hours and neutralized with sodium hydroxide. 3. (Deacylation step by alkaline hydrolysis) Water and sodium hydroxide (solid) were added to the neutralized solution so that the final volume of ethanol was 50% by volume and the final concentration of sodium hydroxide was 1.7% by mass. The mixture was heated under reflux at 70°C for 1 hour and neutralized with hydrochloric acid to obtain a reaction solution containing R1-valigenol.

[0020] R 1 - Measurement of the amount of barigenol extracted The resulting reaction solution was analyzed by HPLC (see below for conditions) to detect R1-valigenol, and the amount of R1-valigenol extracted (mg) was quantified by comparing it with a pre-prepared calibration curve. The extraction rate of R1-valigenol was determined using the following formula. Amount of R1-valigenol extracted from 10g of tea blossoms (mg) =HPLC analysis result (mg / mL) × reaction volume (mL) × crude extract volume (mL) / 10 Column: GL Sciences, Inertsil, ODS-3, 4.6 × 250 mm, 4 μm Solvent: Acetonitrile: Methanol: Water (45:30:40), Isocratic analysis method Wavelength: UV 210nm Flow rate: 1.2ml / min Column oven: 40 degrees The amount of R1-valigenol obtained in Production Example 1 was 212 mg, and the amount of R1-valigenol obtained in Production Example 2 was 190 mg.

[0021] Test Example 1 (R obtained in the extraction process) 1 -Valigenol) The extraction process was carried out according to Production Example 1 or Production Example 2, except that the concentrations of ethanol and sodium hydroxide in the extraction solvent were adjusted to the concentrations shown in Table 1 (the deglycoside and deacylation steps were omitted). Subsequently, the R1-valigenol content in the crude extract was measured by HPLC, and the amount of R1-valigenol extracted from 10 g of tea flowers was calculated. The results are shown in Table 1. In this test example, we investigated whether R1-valigenol could be obtained by processing only the extraction steps of Production Examples 1 and 2. R1-valligenol was not obtained regardless of the presence or absence of ethanol and sodium hydroxide. This indicates that R1-valligenol cannot be obtained from the extraction process alone, regardless of the concentrations of sodium hydroxide and ethanol. This is thought to be because R1-valligenol is extracted as a saponin modified with sugar chains and acyl groups, and not as free R1-valligenol.

[0022] Table 1 TIFF0007906490000001.tif57141

[0023] Test Example 2 (R obtained from extraction process and acid hydrolysis treatment) 1 -Valigenol) The extraction process was carried out according to either Production Example 1 or Production Example 2, except that the extraction solvent was adjusted to the ethanol and sodium hydroxide concentrations shown in Table 2. Subsequently, the deglycoside step by acid hydrolysis was performed according to either Production Example 1 or Production Example 2 to obtain the reaction solution (the deacylation step was not performed). The R1-valigenol content in the reaction solution neutralized by HPLC was measured, and the amount of R1-valigenol extracted from 10 g of tea flowers was calculated. The results are shown in Table 2. In this test example, by performing only the extraction step and the deglycoside step by acid hydrolysis as in Production Examples 1 and 2, the possibility that the sodium hydroxide added in the extraction step replaced the deacylation step by alkaline hydrolysis was investigated. As a result, when extraction was performed with the addition of 0.5% sodium hydroxide, 28 mg of R1-valigenol was obtained with 0% ethanol, 12 mg with 40% ethanol, and 19 mg with 60% ethanol. This amount was very small compared to the amount of R1-valigenol obtained in Production Example 1 or Production Example 2 (Production Example 1: 212 mg, Production Example 2: 190 mg). This indicates that the extraction step with added sodium hydroxide does not replace the deacylation step by alkaline hydrolysis.

[0024] Table 2 TIFF0007906490000002.tif62142

[0025] Test Example 3: Investigation of Ethanol Concentration in the Extraction Process The extraction process, deglycoside step by acid hydrolysis, and deacylation step by alkaline hydrolysis were carried out according to Production Example 1 or Production Example 2, except that the ethanol concentration was set to the values ​​shown in Table 1, and the amount of R1-valigenol extracted was measured. The results are shown in Table 3. In this test example, the effect of the ethanol concentration of the extraction solvent on the amount of R1-valigenol extracted in the extraction process of Production Examples 1 and 2 was investigated. In Production Example 1, where sodium hydroxide was not added, the amount of R1-valligenol extracted using 60% ethanol was 212 mg, and the amount of R1-valligenol extracted decreased as the ethanol concentration decreased. In Production Example 2, where sodium hydroxide was added, the amount of R1-valligenol extracted was equivalent to that in Production Example 1 (ethanol concentration 60% by volume, no sodium hydroxide added) even at 0% and 40% ethanol concentrations. From the above, it was found that by adding sodium hydroxide to the extraction solvent, R1-valigenol can be sufficiently extracted even when the amount of ethanol used in the extraction solvent is reduced.

[0026] Table 3 TIFF0007906490000003.tif36141

[0027] Test Example 4: Investigation of Sodium Hydroxide Concentration in the Extraction Process Except for using water instead of aqueous ethanol and adjusting the sodium hydroxide concentration to match that shown in Table 4, the extraction process, the deglycoside deconjugation process by acid hydrolysis, and the deacylation process by alkaline hydrolysis were carried out according to Production Example 2, and the amount of R1-valigenol extracted was measured. The results are shown in Table 4. In this test, the effect of the sodium hydroxide concentration of the extraction solvent on the amount of R1-valigenol extracted in the extraction process of Production Examples 1 and 2 was investigated. The addition of sodium hydroxide to the extraction solvent was shown to increase the extraction efficiency of R1-valigenol. This was considered to be because the use of sodium hydroxide in the extraction process increased the extraction efficiency of the saponin, as the amount of R1-valigenol extracted when both sodium hydroxide and ethanol were 0% was 156 mg. From the above, it was found that R1-valigenol can be sufficiently extracted even when the amount of ethanol used as the extraction solvent is reduced by adding 0.1% or more sodium hydroxide.

[0028] Table 4 TIFF0007906490000004.tif57142

[0029] Test Example 5: Investigation of conditions for the deacylation process by alkaline hydrolysis The extraction, deglycosylation by acid hydrolysis, and deacylation by alkaline hydrolysis steps were performed according to Production Example 1 (conventional method without alkaline extraction), except that the sodium hydroxide concentration and reaction time in the deacylation step by alkaline hydrolysis were as shown in Table 5, and the ethanol concentration in the extraction step was set to 0. The amount of R1-valigenol extracted was then measured. The results are shown in Table 5. This test investigated the possibility that the deacylation step by alkaline hydrolysis in Production Example 1 was insufficient. In the alkaline hydrolysis deacylation step of Production Example 1, 156 mg of R1-valigenol was extracted under the conditions of 1.7% by mass sodium hydroxide and a reaction time of 1 hour. The extraction efficiency of R1-valigenol under other conditions was equivalent. This indicates that the alkaline decomposition treatment in Production Example 1 was completely performed, and that the addition of alkali in the extraction step of Production Example 2 does not compensate for the effect of the alkaline decomposition treatment in the decomposition step, but rather has an effect entirely separate from the alkaline decomposition treatment in the decomposition step.

[0030] Table 5 TIFF0007906490000005.tif26136

[0031] Test Example 6: Examination of the parts of the tea plant In the extraction process, 25 g of a mixture of dried tea leaves and stems was used instead of dried tea flowers, 125 ml of a 40% ethanol aqueous solution was used as the extraction solvent, and the amount of sodium hydroxide added was 0.625 g. Except for these differences, the extraction process, the deglycoside deconjugation process by acid hydrolysis, and the deacylation deacylation process by alkaline hydrolysis were carried out according to Production Example 1 or Production Example 2, and the amount of R1-valigenol extracted was measured. The results are shown in Table 6. This test investigated whether Production Example 1 or Production Example 2 can be applied to tea leaves and stems. When sodium hydroxide was not used as the extraction solvent, 7.2 mg of R1-valigenol was extracted, whereas the amount of R1-valigenol extracted increased with the addition of 0.5% sodium hydroxide. This indicates that the addition of alkali during the extraction process increases the amount of R1-valigenol extracted not only from tea flowers but also from tea leaves and stems.

[0032] Table 6 TIFF0007906490000006.tif36138

[0033] Test Example 7: Manufacturing Example of Tea Flower Extract This test investigated whether Production Example 2 of the present invention could be industrially implemented. 100 g of pulverized dried tea flowers were added to 1 L of a 0.5% sodium hydroxide aqueous solution, heated under reflux at 80°C for 2 hours, separated into solid and liquid components by centrifugation, cooled, neutralized, and concentrated in an evaporator to 120 mL. 20 mL of 36% concentrated hydrochloric acid was added to the crude extract, heated under reflux at 70°C for 3 hours, and neutralized with sodium hydroxide. Then, sodium hydroxide, ethanol, and water were added to make a 1.7% sodium hydroxide-44% ethanol aqueous solution, and heated under reflux at 70°C for 1 hour. After neutralizing the reaction solution with hydrochloric acid, the volume of the reaction solution became 130 mL. The reaction solution was added to 2.6 L of water and centrifuged at 4000 g for 15 minutes. The supernatant after centrifugation was removed, and the precipitate was dried to obtain the tea flower extract. From 100g of tea flower raw material, 9.4g of tea flower extract was obtained, containing 1.9g of R1-valigenol. Thus, it has been demonstrated that R1-valigenol can be efficiently produced from ground tea material even on an industrial scale using the method of the present invention.

Claims

1. The following steps; (1) A step of extracting the ground tea material with an aqueous alkali metal hydroxide solution or an aqueous alkali metal hydroxide alcohol solution and (2) The process includes a step of treating the extract obtained in step (1) with acid hydrolysis and alkaline hydrolysis, R 1 - A method for preparing barigenol, The alkali metal hydroxide content in the alkali metal hydroxide aqueous solution and the alkali metal hydroxide aqueous alcohol solution is 0.05 to 2.5% by mass. The alcohol content in the alkali metal hydroxide aqueous alcohol solution is 45% by volume or less. The method wherein the alcohol in step (1) is a lower alcohol having 1 to 3 carbon atoms.

2. The method according to claim 1, wherein the alkali metal hydroxide is sodium hydroxide or potassium hydroxide.

3. The method according to claim 1 or claim 2, wherein the lower alcohol having 1 to 3 carbon atoms is ethanol.

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