JP7419673B2 - Method for decomposing flavonoid glycosides and method for producing flavonoids - Google Patents

Description

The present invention relates to a method for decomposing flavonoid glycosides and a method for producing flavonoids.

Flavonoids are a group of naturally occurring organic compounds and are contained in flowers, leaves, roots, stems, fruits, seeds, etc. of various plants, including citrus fruits and beans. Flavonoids have different characteristics and actions depending on the type, but most of them have strong antioxidant effects. For example, polymethoxyflavone, a flavonoid found in citrus fruits, is known to have antioxidant, carcinogenic, antibacterial, antiviral, antiallergic, melanin production, and blood sugar level suppressing effects. It is expected to be applied to a variety of applications such as pharmaceuticals, health foods, and cosmetics.

As a method for producing flavonoids from citrus fruits, for example, a method is known in which flavonoids are extracted from the peel of citrus fruits with an aqueous ethanol solution and the extracted flavonoids are recovered from the solution (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2005-145824

However, conventional methods for producing flavonoids have a problem in that the yield of flavonoids is low. Therefore, there is a need to develop a production method that can improve the yield of flavonoids.

For example, the peel of citrus fruits contains not only flavonoids but also larger amounts of flavonoid glycosides, and if these can be recovered as flavonoids, it is possible to improve the yield of flavonoids. Examples of methods for decomposing flavonoid glycosides into flavonoids include a method of reacting flavonoid glycosides with an acid such as hydrochloric acid. However, this method has problems in that the used acid may remain and be mixed into the product, and side reaction products between the acid and the flavonoid may be generated. As a method for removing impurities such as acids and by-products, there is a method of separating and purifying flavonoids in decomposition products by liquid chromatography, but this method has the problems of high cost and poor production efficiency. Therefore, a new method for decomposing flavonoid glycosides that does not use acids is required.

The present invention has been made in view of the above-mentioned problems of the prior art, and it provides a flavonoid glycoside that can efficiently decompose flavonoid glycosides into flavonoids without using acids and improve the yield of flavonoids. The present invention aims to provide a decomposition method and a method for producing flavonoids.

In order to achieve the above object, the present invention disposes a raw material container containing a raw material liquid containing flavonoid glycosides in an autoclave, and hydrothermally treats the raw material liquid to convert the flavonoid glycosides into flavonoids. Provided is a method for decomposing flavonoid glycosides, comprising a hydrothermal treatment step for decomposition, wherein the surface in contact with the raw material liquid in the raw material container is a surface having a contact angle with water of less than 35° at a measurement temperature of 25 ° C. do.

According to the above method, flavonoid glycosides can be efficiently decomposed into flavonoids by hydrothermal treatment without using acids. Moreover, by using this method, flavonoids can be produced efficiently at low cost.

In addition, the present inventors discovered that in a method of decomposing flavonoid glycosides by hydrothermal treatment, the glycoside decomposition products precipitate after the hydrothermal treatment, and the glycoside decomposition products are deposited on the surface in contact with the raw material liquid in the raw material container. It has been found that a phenomenon of adhesion occurs. Glycoside decomposition products include flavonoids resulting from glycoside decomposition and caramel reaction products of produced sugars. If a stainless steel container or a container made of polytetrafluoroethylene resin, which is a common raw material container, is used as is, precipitates will strongly adhere to the surface of the raw material container that comes into contact with the raw material liquid, so remove it. Therefore, it is necessary to rub the contact surface strongly for a long time with a medicine spoon or the like, and it takes time to remove the glycoside decomposition products. Furthermore, since the contact surface with the raw material liquid in the raw material container is strongly rubbed with a medicine spoon or the like, there is a risk that the contact surface or the medicine spoon or the like may be scraped and foreign matter may be mixed in. In order to solve these problems, the present inventors conducted extensive studies and found that the surface in contact with the raw material liquid in the raw material container has a contact angle with water of less than 35° at a measurement temperature of 25°C. It has been found that by doing so, it is possible to suppress the adhesion of glycoside decomposition products to the contact surface and improve the yield of flavonoids even when the time for taking out the glycoside decomposition products is short. The present invention relates to the fact that when the surface in contact with the raw material liquid in the raw material container is a surface that has a contact angle with water of less than 35° at a measurement temperature of 25°C, adhesion of glycoside decomposition products to the contact surface can be suppressed. They speculate as follows. That is, glycoside decomposition products are hydrophobic. On the other hand, the contact surface with the raw material liquid in the raw material container has a contact angle with respect to water of less than 35° at a measurement temperature of 25° C., and is hydrophilic. Therefore, the hydrophobic glycoside decomposition product and the hydrophilic contact surface for the raw material liquid repel each other. Thereby, the precipitated glycoside decomposition product is less likely to adhere to the contact surface of the raw material container.

In the disassembly method, the contact surface may be an enameled surface. Since the contact surface is an enamel-treated surface, the contact angle of the contact surface with water at a measurement temperature of 25°C can be further reduced, and the precipitated glycoside decomposition products are more likely to contact the raw material container. It becomes difficult to adhere.

In the decomposition method, the contact surface may be a surface treated with a polysilazane compound. Since the contact surface is a surface treated with a polysilazane compound, the contact angle of the contact surface with water at a measurement temperature of 25°C can be further reduced, and the precipitated glycoside decomposition product can be moved against the raw material container. This makes it even more difficult to adhere.

The polysilazane compound may be perhydropolysilazane. Since the polysilazane compound is perhydropolysilazane, the contact angle of the contact surface with water at the measurement temperature of 25°C can be further reduced, and the precipitated glycoside decomposition products are less likely to adhere to the raw material container. Become.

In the decomposition method, the hydrothermal treatment may be performed by supplying water vapor into the autoclave from the outside. By supplying water vapor from the outside, the temperature and pressure inside the autoclave can be increased in a short time, and a hydrothermal treatment environment can be easily created and maintained.

In the hydrothermal treatment step of the decomposition method, the pressure inside the autoclave may be 0.2 to 1.6 MPa and the temperature may be 120 to 200°C. By performing the hydrothermal treatment within the above pressure and temperature range, flavonoid glycosides can be more efficiently decomposed into flavonoids, and the yield of flavonoids can be further improved.

In the above decomposition method, the flavonoid glycoside may contain a sudatitin glycoside and/or a demethoxysudatitin glycoside. According to the above decomposition method, sudatitin glycosides and demethoxysudatitin glycosides can be decomposed particularly efficiently.

The present invention also provides a method for producing flavonoids, comprising a decomposition step of decomposing flavonoid glycosides by the decomposition method of the present invention, and an extraction step of extracting flavonoids from the decomposition products obtained in the decomposition step. provide. According to such a production method, flavonoids can be produced in high yield, at low cost, and efficiently.

According to the present invention, it is an object of the present invention to provide a method for decomposing flavonoid glycosides, which can efficiently decompose flavonoid glycosides into flavonoids without using an acid, and which can improve the yield of flavonoids, and a method for producing flavonoids. I can do it.

FIG. 2 is a schematic cross-sectional view showing an example of an autoclave used in the method for decomposing flavonoid glycosides according to the present embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below, with reference to the drawings as the case may be. However, the present invention is not limited to the following embodiments. Furthermore, the dimensional ratios in the drawings are not limited to the ratios shown.

In this specification, a numerical range indicated using "~" indicates a range that includes the numerical values written before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described stepwise in this specification, the upper limit or lower limit of the numerical range of one step can be arbitrarily combined with the upper limit or lower limit of the numerical range of another step. In the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with the values shown in the examples. "A or B" may include either A or B, or may include both. The materials exemplified herein can be used alone or in combination of two or more, unless otherwise specified.

(Method for decomposing flavonoid glycosides)
In the method for decomposing flavonoid glycosides according to the present embodiment, a raw material container containing a raw material liquid containing flavonoid glycosides is placed in an autoclave, and the raw material liquid is hydrothermally treated to decompose the flavonoid glycosides. The method includes a hydrothermal treatment step for decomposing into flavonoids, and the surface of the raw material container that comes into contact with the raw material liquid is a surface that has a contact angle with water of less than 35° at a measurement temperature of 25°C.

Flavonoid glycosides are hydrophilic compounds having a structure in which a flavonoid and a sugar are bonded through a glycosidic bond. Flavonoids, which are the source of flavonoid glycosides, are aromatic compounds with a phenylchroman skeleton as their basic structure, and include flavones, flavonols, flavanones, flavanonols, isoflavones, anthocyanins, flavanols, chalcone, and aurone. etc. Among these, the flavonoid may be polymethoxyflavone, which is a flavonoid.

Examples of polymethoxyflavone include sudatitin, demethoxysudatitin, nobiletin, tangeretin, pentamethoxyflavone, tetramethoxyflavone, heptamethoxyflavone, and the like. Among these, the polymethoxyflavone may be sudatitin or demethoxysudatitin.

The sugar that is the source of the flavonoid glycoside is not particularly limited, and includes known sugars that can form a glycoside by bonding with the above-mentioned flavonoid through a glycosidic bond.

The raw material liquid to be subjected to hydrothermal treatment is a raw material containing a flavonoid glycoside dissolved or dispersed in water. Note that the raw material may contain components other than flavonoid glycosides. Examples of other components include flavonoids, water-soluble dietary fiber, poorly soluble dietary fiber, and sugars.

The content of flavonoid glycosides in the raw material is preferably 0.1% by mass or more, more preferably 0.25 to 30% by mass, and more preferably 0.5 to 30% by mass, based on the total solid content of the raw material. More preferably, it is 5% by mass. When the raw material further contains flavonoids, the content of flavonoid glycosides is preferably 0.25 parts by mass or more, and 0.5 to 100 parts by mass, per 1 part by mass of flavonoids. is more preferable, and even more preferably 5 to 50 parts by mass.

The concentration of the raw material in the raw material liquid is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 10% by mass, based on the total amount of the raw material liquid. . When the concentration of the raw material is 1% by mass or more, the yield of decomposition products increases, so the amount of flavonoids obtained in a single decomposition treatment tends to increase; when the concentration of the raw material is 30% by mass or less, flavonoid glycosides There is a tendency that the decomposition of can be performed more reliably and efficiently.

Specifically, flowers, leaves, roots, stems, fruits, seeds, etc. of plants and seaweed can be used as raw materials. In particular, since the pericarp contains a large amount of polymethoxyflavones and their glycosides, the juice residue of citrus fruits can be suitably used. Moreover, the raw material may be a dry powder obtained from citrus fruits or a dry powder obtained from the peel of citrus fruits. Examples of citrus fruits include Sudachi, Satsuma mandarin orange, Ponkan, and Shikwasa. The citrus fruits may be sudachi containing a large amount of polymethoxyflavones such as sudatitin and demethoxysudatitin, and their glycosides.

Hydrothermal treatment can be performed by placing a raw material container containing a raw material liquid in an autoclave and heating it at a temperature exceeding 100° C. while keeping the autoclave sealed. By heating the raw material liquid in the autoclave, the interior of the autoclave becomes a heated and pressurized environment, and hydrothermal treatment (hydrothermal synthesis) is performed. The hydrothermal treatment may be performed while stirring the raw material liquid.

Further, the hydrothermal treatment may be performed by supplying water vapor into the autoclave from the outside. For example, by supplying high-temperature, high-pressure saturated steam into the autoclave, the interior of the autoclave becomes a heated and pressurized environment, and hydrothermal treatment (hydrothermal synthesis) is performed. The autoclave is not particularly limited and may be either vertical or horizontal. When using a vertical autoclave, the raw material container containing the raw material liquid may be placed on a stand. When using a vertical autoclave, water may be placed in the tank of the autoclave in addition to the raw material liquid. On the other hand, when using a horizontal autoclave, hydrothermal treatment can be performed, for example, by the following method.

FIG. 1 is a schematic cross-sectional view showing an example of an autoclave (horizontal circulation type autoclave) used in the above decomposition method. In an autoclave 100 shown in FIG. 1, a cylindrical muffle furnace 3 with both ends open is arranged in a cylindrical pressure vessel (tank) 2 equipped with a sealable door (sealed door) 1 at one end. An air passage 4 is formed between the inner wall of the pressure vessel 2 and the outer wall of the muffle furnace 3. Further, one end of the muffle furnace 3 is connected to a circulation fan 8 via a cooler 6, a heater 5, and an air passage 9. The circulation fan 8 is attached to the rotating shaft of a motor 7 located outside the end of the pressure vessel 2 opposite to the closed door 1 .

A movable table 12 is arranged inside the muffle furnace 3, and a raw material container 11 containing a raw material liquid 10 is placed on the movable table 12. A boiler 13 for supplying steam is connected to the pressure vessel 2 via a pipe provided with a valve 14. Furthermore, a pipe provided with a pressure gauge 15 and a pressure valve 16 is connected to the pressure vessel 2 in order to adjust the internal pressure.

In the hydrothermal treatment process, steam supplied from the boiler 13 into the pressure vessel 2 circulates within the autoclave 100 along the arrows in FIG. That is, the water vapor is sent out to the air path 4 by the circulation fan 8 and directed toward the closed door 1, and then flows into the muffle furnace 3, flows around the raw material container 11, and flows through the cooler 6, heater 5, and air path 9. The air passes through the air, is sucked into the circulation fan 8, and is sent out to the air path 4 again. The amount of water vapor supplied is adjusted by operating the valve 14 so that the inside of the autoclave 100 has a predetermined temperature and pressure. Note that the temperature inside the autoclave 100 may be adjustable using the heater 5 and the cooler 6. Further, the pressure inside the autoclave 100 may be adjusted by opening and closing the pressure valve 16. Through the above operations, the inside of the autoclave 100 becomes a heated and pressurized environment, and hydrothermal treatment (hydrothermal synthesis) is performed.

The raw material container 11 includes a contact surface 20 with the raw material liquid 10 . The contact surface 20 is a surface of the inner surface of the raw material container 11 that comes into contact with the raw material liquid 10 . The contact surface 20 is a surface whose contact angle with water at a measurement temperature of 25° C. is less than 35°. The entire inner surface of the raw material container 11 may have a contact angle with water of less than 35° at a measurement temperature of 25°C. The contact angle of the outer surface of the raw material container 11 with respect to water at a measurement temperature of 25° C. is not particularly limited.

The contact angle of the contact surface 20 with water at a measurement temperature of 25° C. is less than 35°, which further suppresses the adhesion of glycoside decomposition products to the contact surface 20, and when the time for taking out the glycoside decomposition products is short. The angle is preferably less than 15°, more preferably less than 5°, because the yield of flavonoids can be further improved even if the angle is lower than 15°. The contact angle of the contact surface 20 with respect to water at a measurement temperature of 25° C. may be 0.01° or more.

The contact angle with respect to water at a measurement temperature of 25° C. refers to the value measured as follows. That is, the measurement is performed using a contact angle meter in an environment at a temperature of 25°C. The contact angle of the contact surface with the raw material liquid 10 in the raw material container 11 is measured five times using water, and the average value is taken as the contact angle. As the water, for example, ultrapure water can be used.

The material of the raw material container 11 is not particularly limited as long as it can withstand the temperature and pressure during the hydrothermal treatment and contains few impurities in the raw material liquid 10. For example, metals such as stainless steel, titanium, and alloys thereof, etc. Alternatively, chemically stable and heat-resistant resins such as polytetrafluoroethylene, polyimide, and polyamideimide can be used.

The shape of the raw material container 11 is not particularly limited, but may be, for example, tank-shaped, bottle-shaped, cup-shaped, tray-shaped, or drum-shaped.

The surface of the raw material container 11 that comes into contact with the raw material liquid 10 is preferably a surface that has been subjected to a hydrophilic treatment. Examples of the hydrophilic treatment include enameling treatment, treatment with a polysilazane compound, treatment with an alkoxysilane compound, and plasma treatment with oxygen, nitrogen, etc. The hydrophilic treatment is performed using enamel treatment or polysilazane because it can further suppress the adhesion of glycoside decomposition products to the contact surface 20 and further improve the yield of flavonoids even if the time for taking out the glycoside decomposition products is short. Treatment with a compound is preferred.

Examples of the polysilazane compound include perhydropolysilazane. The polysilazane compound is perhydropolysilazane because it can further suppress the adhesion of glycoside decomposition products to the contact surface 20 and further improve the yield of flavonoids even if the time for taking out the glycoside decomposition products is short. It is preferable.

The reaction conditions for the hydrothermal treatment are not particularly limited, but may be, for example, 110 to 300°C for 0.5 to 20 hours. The reaction temperature is preferably 120 to 200°C, more preferably 120 to 190°C, even more preferably 140 to 185°C. When the reaction temperature is 110°C or higher, the hydrothermal reaction tends to occur better, and when the reaction temperature is 300°C or lower, carbonization of the raw materials and flavonoids is difficult to progress, and the yield tends to be further improved. . The reaction time is preferably 0.5 to 20 hours, more preferably 1 to 10 hours. When the reaction time is 0.5 hours or more, the reaction tends to proceed more easily, and when the reaction time is 20 hours or less, it tends to be easier to balance the progress of the reaction and cost.

The pressure inside the autoclave during the hydrothermal treatment may be the saturated vapor pressure corresponding to the above-mentioned reaction temperature or higher, but from the viewpoint of the pressure resistance of the apparatus, it is preferably the saturated vapor pressure. When supplying steam from the boiler into the autoclave, it is preferable to supply saturated steam at the above-mentioned reaction temperature. The pressure inside the autoclave during the hydrothermal treatment can be, for example, 0.2 to 1.6 MPa.

By performing hydrothermal treatment under the above conditions, flavonoid glycosides can be efficiently decomposed into flavonoids (more specifically, into flavonoids and sugars).

Next, after performing the hydrothermal treatment step by the method described above, a depressurization step of reducing the pressure inside the autoclave may be performed. The pressure inside the autoclave can be reduced by opening a pressure valve and discharging the steam inside the autoclave. The pressure reduction speed during pressure reduction can be adjusted with a pressure valve. It is preferable to reduce the pressure while checking the pressure inside the autoclave using a pressure gauge. The pressure reduction rate in the pressure reduction step is not particularly limited, but may be, for example, 140 kPa/min or less. The pressure reduction rate in the pressure reduction step is not particularly limited, but may be, for example, 5 kPa/min or more. In addition, in the pressure reduction process, the pressure reduction speed does not always need to be constant, and may be varied.

After the pressure inside the autoclave is reduced to atmospheric pressure (0.1 MPa) by the above-mentioned pressure reduction step, the raw material liquid can be cooled to room temperature by natural cooling. Thereby, a decomposition product of flavonoid glycoside (glycoside decomposition product) can be obtained.

(Method for producing flavonoids)
The method for producing flavonoids according to the present embodiment includes a decomposition step of decomposing flavonoid glycosides, and an extraction step of extracting flavonoids from the decomposition products obtained in the decomposition step. The decomposition step is a step of decomposing flavonoid glycosides using the flavonoid glycoside decomposition method according to the present embodiment described above.

In the extraction step, flavonoids are extracted from the decomposition products obtained in the decomposition step. In addition to flavonoids, the decomposition products include sugars, flavonoid glycosides remaining without decomposition, water-soluble and sparingly soluble cellulose, and their decomposition products. Here, flavonoids are hydrophobic, whereas sugars, flavonoid glycosides, water-soluble cellulose, and their decomposition products are hydrophilic. Therefore, the components insoluble in the aqueous solution after the hydrothermal treatment contain flavonoids at a high concentration, and the flavonoids can be concentrated by separating the aqueous solution and the insoluble components after the hydrothermal treatment. Furthermore, flavonoids can be further extracted by dissolving the water-insoluble matter in a solvent that dissolves flavonoids, such as ethanol, ethyl acetate, hexane, toluene, etc., or a mixed solvent thereof, and removing the insoluble matter by filtration etc.・Can be purified. Thereafter, high concentration flavonoids can be obtained by drying the filtrate.

By the above method, flavonoids can be efficiently produced with high yield. The flavonoid produced by the production method of this embodiment may be polymethoxyflavone, sudatitin and/or demethoxysudatitin. The production method of the present embodiment is suitable for producing polymethoxyflavone, particularly sudatitin and demethoxysudatitin, and can greatly improve the yield thereof.

Although the preferred embodiments of the present invention have been described above in detail, the present invention is not limited to the above embodiments. For example, although the autoclave 100 shown in FIG. 1 is equipped with one circulation fan 8, an autoclave equipped with a plurality of circulation fans may be used. For example, if circulation fans are installed at multiple locations within the muffle furnace 3, the temperature within the muffle furnace 3 can be easily made uniform. Therefore, even if a plurality of raw material containers containing raw material liquids are arranged in an autoclave, the temperature of each raw material liquid tends to be uniform. Further, although the autoclave 100 shown in FIG. 1 includes a cooler 6 and a heater 5, it is not necessary to include one or both of them.

EXAMPLES Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Example 1)
Sudachi pericarp extract powder (manufactured by Ikeda Yakusou Co., Ltd.) containing 1000 mass ppm of sudatitin and 9000 mass ppm of sudatitin derived from glycosides was dissolved/dispersed in ultrapure water to a concentration of 5% by mass, and Sudachi pericarp extract was An aqueous dispersion was prepared. 12 L of this aqueous dispersion was put into a container. As the container, an 18.5L enamel tank (manufactured by Noda Horo) was used. An enamel tank is a steel tank whose entire inner surface is treated with enamel. The Sudachi pericarp extract aqueous dispersion was then placed in a hot air circulation autoclave (manufactured by Ashida Seisakusho Co., Ltd.) with an internal volume of 2 m ³ for 1 hour at 180° C. to undergo glycoside decomposition treatment. In the decomposition process, saturated steam at 180°C is supplied from the boiler into the tank (pressure vessel) of the autoclave, and the amount of steam supplied and the pressure valve are adjusted so that the pressure inside the tank is 1 MPa, which is the saturated steam pressure of water at 180°C. I made adjustments while doing so. The pressure inside the tank after the decomposition treatment was 0.9 MPa, and the temperature inside the tank was 180°C. The autoclave was naturally cooled for 10 minutes until the pressure inside the tank was 0.7 MPa and the temperature inside the tank was 165°C. After natural cooling, the valve was opened and compressed air at a pressure of 1 MPa was sent into the tank using a compressor attached to the device. The pressure in the tank immediately after the compressed air was introduced was over 1 MPa, so by manually opening and closing the exhaust valve, compressed air was introduced into the tank while maintaining the pressure at no lower than 0.75 MPa. , started cooling with compressed air. During cooling, cooling was carried out while appropriately lowering the pressure inside the tank so as not to fall below the saturated water vapor pressure at that point. Two hours after the start of cooling with compressed air, the temperature of the aqueous dispersion dropped below 100°C (the saturated water vapor pressure of the aqueous dispersion fell below normal pressure (0.1 MPa)), so the lid of the tank was opened and the container was removed. was taken out and naturally cooled to room temperature (25°C). After cooling, the glycoside decomposition products precipitated and attached to the inner surface of the container were taken out using a medicine spoon for 5 minutes. Table 1 shows the yield of the extracted glycoside decomposition product.

Next, the solution and solid content in the container were filtered under reduced pressure using a diaphragm pump using a hydrophilized PTFE membrane filter with an opening of 0.2 μm (Omnipore 0.2 μm JG (trade name, Merck Millipore)). did. The separated solution contains dissolved sugars derived from decomposed glycosides, and the solid substance contains a high concentration of decomposed sudatitin, so the obtained solid substance was placed in a 200cc glass beaker. and dried in an oven at 120°C for 5 hours to obtain a powdery glycoside decomposition product. Next, the glycoside decomposition product was adjusted to a 5% dispersion in ethanol, treated under reflux at 60°C for 1 hour, sudatitin was extracted into ethanol, and filtered using a hydrophilic PTFE membrane filter with an opening of 0.2 μm ( Omnipore 0.2 μm JG (Merck-Millipore, trade name)) was filtered under reduced pressure using a diaphragm pump to obtain a sudatitin solution. The obtained sudatitin solution was vacuum-dried using a diaphragm pump under heating at 60° C. to obtain a concentrated sudatitin powder.

(Example 2)
A concentrated powder of sudatitin was obtained in the same manner as in Example 1, except that a stainless steel tank treated with hydrophilic treatment was used as the container instead of the 18.5 L enamel tank. The stainless steel tank that underwent hydrophilic treatment was made by spraying perhydropolysilazane with a solid content of 2% on the entire inner surface of a 15L stainless steel tank (manufactured by Nitto Metal Industry Co., Ltd., container depth: 27cm). It was obtained by baking at ℃ for 1 hour.

(Comparative example 1)
Powdery sudatitin concentrated powder was prepared in the same manner as in Example 1, except that a 15L stainless steel tank (manufactured by Nitto Metal Industry Co., Ltd., container depth: 27cm) was used as the container instead of the 18.5L enamel tank. Obtained.

<Evaluation method>
(Measurement of sudatitin concentration in sudatitin concentrated powder)
The sudatitin concentration of the sudatitin concentrated powder obtained in each example and comparative example was measured by the following method. First, 0.1 g of sudatitin concentrated powder was dissolved/dispersed in ethanol to a dilution ratio of 500, and filtered through a PTFE filter with a pore size of 0.1 μm to obtain an ethanol solution. Component analysis of this ethanol solution was performed by high performance liquid chromatography (HPLC). A calibration curve was created using a commercially available sudatitin standard purified sample as a standard substance, and the sudatitin concentration in the sudatitin concentrated powder was estimated using the calibration curve. As the HPLC device, "Chrome Master" manufactured by Hitachi High-Tech was used. The results are shown in Table 1.

(Calculation of sudatitin yield)
The yield of sudatitin was determined from the mass of the sudatitin concentrated powder and the sudatitin concentration. The yield indicates the ratio of the mass of sudatitin contained in the obtained sudatitin concentrated powder to the total mass of sudatitin and glycoside-derived sudatitin contained in the aqueous dispersion added to the raw material container.

<Measurement of contact angle>
The contact angle with water at a measurement temperature of 25° C. was measured using a contact angle meter DM-501 manufactured by Kyowa Interface Science Co., Ltd. in an environment with a humidity of 40% RH. The contact angle of the surface in contact with the raw material liquid in the raw material container was measured five times using ultrapure water, and the average value was obtained as the contact angle. The amount of water dropped was 1 μl, and the contact angle was read after standing still for 3 seconds. As water, ultrapure water (electrical resistivity: 18 MΩ·cm or more) was used, which was collected from an ultrapure water production device (PRO-0500 (model number), manufactured by Organo Co., Ltd.). The results are shown in Table 1.

The sudatitin concentrations in the sudatitin concentrated powders obtained in Examples and Comparative Examples were all above 9% by mass, confirming that the glycoside decomposition treatment was carried out appropriately. In Examples 1 and 2, in which the contact angle of the surface in contact with the raw material liquid in the raw material container was less than 35°, the yield exceeded 80% by mass, and the glycoside decomposition product was efficiently recovered. .

1... Sealed door, 2... Pressure vessel, 3... Muffle furnace, 4... Air path, 5... Heater, 6... Cooler, 7... Motor, 8... Circulation fan, 9... Air path, 10... Raw material liquid, 11... Raw material Container, 12...Movable base, 13...Boiler, 14...Valve, 15...Pressure gauge, 16...Pressure valve, 20...Contact surface.

Claims (8)

A hydrothermal treatment step in which a raw material container containing a raw material liquid containing flavonoid glycosides is placed in an autoclave and the raw material liquid is hydrothermally treated to decompose the flavonoid glycosides into flavonoids;
The contact surface with the raw material liquid in the raw material container is a surface whose contact angle with water at a measurement temperature of 25 ° C. is less than 35 °,
The method for decomposing flavonoid glycosides , wherein the contact surface is an enameled surface. A hydrothermal treatment step in which a raw material container containing a raw material liquid containing flavonoid glycosides is placed in an autoclave and the raw material liquid is hydrothermally treated to decompose the flavonoid glycosides into flavonoids;
The contact surface with the raw material liquid in the raw material container is a surface whose contact angle with water at a measurement temperature of 25 ° C. is less than 35 °,
The method for decomposing flavonoid glycosides , wherein the contact surface is a surface treated with a polysilazane compound. The decomposition method according to claim 2 , wherein the polysilazane compound is perhydropolysilazane. The decomposition method according to any one of claims 1 to 3 , further comprising a pressure reduction step of reducing the pressure inside the autoclave after the hydrothermal treatment step. The decomposition method according to any one of claims 1 to 4 , wherein the hydrothermal treatment is performed by supplying water vapor into the autoclave from the outside. The decomposition method according to any one of claims 1 to 5 , wherein in the hydrothermal treatment step, the pressure in the autoclave is 0.2 to 1.6 MPa and the temperature is 120 to 200°C. The decomposition method according to any one of claims 1 to 6 , wherein the flavonoid glycoside includes sudatitin glycoside and/or demethoxysudatitin glycoside. A decomposition step of decomposing flavonoid glycosides by the method according to any one of claims 1 to 7 ;
an extraction step of extracting flavonoids from the decomposition products obtained in the decomposition step;
A method for producing flavonoids, including:

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