Method to remove hydroxy hydroquinone

Abstract

POPE METHOD REMOVE HYDROQUINONE HYDROXY. a method for removing a hydroxy hydroquinone is disclosed where an aqueous solution containing a hydroxy hydroquinone and a caffeoylquinic acid is brought into contact with an acid clay having a SiO ~ 2 ~ / A1 ~ 2 ~ O ~ 3 ~ ratio of 3-5 With this method, a hydroxy hydroquinone can be selectively removed from an aqueous solution containing hydroxy hydroquinone and a caffeoylquinic acid.

Description

• · • · · METHOD FOR REMOVING HYDROXYHYDROQUINONE Field of invention The present invention relates to a method for selectively removing hydroxyhydroquinone from an aqueous solution. Background of the invention Hydrogen peroxide, known as an oxygen radical, is said to be deeply associated with many diseases, including circulatory diseases such as arteriosclerosis and ischemic heart disease, gastrointestinal diseases, allergic diseases, and eye diseases, as well as mutagenicity and carcinogenicity (Non-patent Document 1). Coffee contains hydrogen peroxide that is spontaneously generated by roasting (Non-patent Document 2). A technology for removing hydrogen peroxide from coffee by adding a catalase, peroxidase, antioxidant, or similar (Patent Documents 1 to 4) has been reported. [Non-patent document 1] Japanese Journal of Nutritional Assessment, 19, 3(2002). [Non-patent document 2] Mutat. Res. 16, 308 (2) (1994) [Patent document 1] JP-B-04-29326 [Patent document 2] JP-A-03-127950 [Patent document 3] JP-A-11-266842 [Patent document 4] JP-A-2003-81824 [Disclosure of the invention] The present invention relates to a method of removing hydroxyhydroquinone from an aqueous solution containing hydroxyhydroquinone and caffeoylquinic acids, which includes contacting the aqueous solution with an acidic clay having a SiO2 / Al2O3 ratio of 3 to 5. The present invention also relates to an aqueous solution containing caffeoylquinic acids, which solution is available by the method described above and has a mass ratio (hydroxyhydroquinone / caffeoylquinic acids) of 0 to 0.005. Method of carrying out the invention It was found that when coffee from which hydrogen peroxide had been removed was given to rats, their urinary hydrogen peroxide level increased due to the generation of hydrogen peroxide in their bodies. It was further found that the generation of hydrogen peroxide in the bodies is caused by hydroxyhydroquinone contained in the coffee. Therefore, it is desirable to remove hydroxyhydroquinone from coffee. Since coffee contains caffeoylquinic acids, which have an excellent hypotensive effect, a reduction in the amount of this effective component during the removal of hydrogen peroxide or hydroxyhydroquinone is undesirable. Therefore, there is a demand for the development of a technology capable of selectively removing hydroxyhydroquinone from coffee while minimizing the reduction in the amount of caffeoylquinic acids present in the coffee. The present invention provides a method for selectively removing hydroxyhydroquinone from an aqueous solution containing hydroxyhydroquinone and caffeoylquinic acids. •·· ··· • · ··· The present inventors therefore conducted research on a method of selectively removing hydroxyhydroquinone from an aqueous solution containing hydroxyhydroquinone and caffeoylquinic acids. As a result, it was found that the benefit described above can be obtained by placing the aqueous solution in contact with a specific acidic clay. According to the present invention, by placing an aqueous solution containing hydroxyhydroquinone and caffeoylquinic acids in contact with a specific acidic clay, hydroxyhydroquinone can be conveniently removed without causing a substantial reduction in the caffeoylquinic acid content. This method is useful as a method for manufacturing health foods and the like.No specific limitations are imposed on the aqueous solution containing hydroxyhydroquinone and caffeoylquinic acids, and examples thereof include coffee such as Brazilian coffee, Colombian coffee, Tanzanian coffee, and Mocha coffee. There are mainly two species of coffee, namely Arabica and Robusta. For coffee preparation, a single type of bean or a mixture of several types of beans may be used. Although no specific limitations are imposed on the roasting method for preparing roasted coffee beans and no specific limitations are imposed on the roasting temperature or roasting environment, the L value, which represents the degree of roasting, to obtain caffeoylquinic acid in high yield in order to reduce hydroxyhydroquinone, is preferably 18 or more, more preferably 20 or more, still possibly from 22 to 30. There is no limitation on the grain extraction.An extract is obtained by extraction with warm water, preferably hot water. As an extraction operation, extraction processes conventionally known as batch extraction and continuous extraction using a column can be employed, as is typically the case. Examples of caffeoylquinic acids that can be removed by the present invention include 3-caffeoylquinic acid, 4-caffeoylquinic acid, 5-caffeoylquinic acid, 3,4-dicaffeoylquinic acid, 4,5-dicaffeoylquinic acid and 3.5- dicaffeoylquinic acid and salts thereof. The concentration of caffeoylquinic acids in an aqueous solution, such as coffee, containing hydroxyhydroquinone and caffeoylquinic acids, is preferably from 0.01 to 2% by mass, more preferably from 0.03 to 1% by mass, and even more preferably from 0.06 to 0.5% by mass. When the aqueous solution was placed in contact with a commonly used white clay other than the white clay preferably used in the present invention, not only hydroxyhydroquinone but also caffeoylquinic acids were inevitably adsorbed onto it, and selective removal of hydroxyhydroquinone was not achieved. The acidic clay to be used in the present invention to obtain caffeoylquinic acid in high yield, to reduce hydroxyhydroquinone, is a naturally occurring acidic clay (montmorillonite clay) having a porous structure... with a high adsorption capacity and specific surface area. The acid clay preferably contains, as general chemical components, SiO2, Al2O3, Fe2O3, CoC and MgO. When used in the present invention, its SiO2 / Al2O3 ratio varies from 3 to 5, preferably from 4 to 5 (as a mass ratio of a product dried at 110 °C), its specific surface area is preferably from 50 to 350 m2 / g, and its pH (as a 5% suspension) preferably varies from 5 to 10, more preferably from 6 to 9.8, even more preferably from 7 to 9.4. The aqueous solution containing hydroxyhydroquinone and caffeoylquinic acids can be contacted with the acid clay by any method, for example, batch treatment and continuous treatment using a column. The commonly employed method is to add the acidic clay in powder form to the aqueous solution, stir the mixture to adsorb hydroxyhydroquinone onto the clay, and perform a filtration operation to obtain a filtrate from which hydroxyhydroquinone has been removed; or to perform continuous treatment using a column filled with acidic clay in granular form, thereby adsorbing hydroxyhydroquinone onto it. The treatment conditions described above can be selected as necessary depending on the type of aqueous solution containing caffeoylquinic acids and hydroxyhydroquinone or the concentration of the extract. When continuous treatment using a column is employed, removal can be achieved by feeding approximately 1 to 100 volumes of the aqueous solution containing caffeoylquinic acids and hydroxyhydroquinone to 1 volume of acidic clay in granular form. • · ·· ·· null. The solution that has passed through the column to remove hydroxyhydroquinone can also be converted into a solid such as a powder or granule by drying it in a manner known as spray drying, lyophilization or hot air drying as is or after concentrating it under reduced or normal pressure. The operation in the present invention can be carried out in an ambient temperature range, preferably from 10 to 40°C. The amount of hydroxyhydroquinone remaining in the aqueous solution containing caffeoylquinic acids obtained in the manner described above is preferably from 0 to 0.005, especially preferably from 0 to 0.001 (mass ratio) in terms of a ratio of (hydroxyhydroquinone / caffeoylquinic acids) to avoid suppression of a hypotensive effect of caffeoylquinic acids by hydroxyhydroquinone. For example, a ratio of (hydroxyhydroquinone / caffeoylquinic acids) in the aqueous solution ranging from approximately 0.01 to 1 (mass ratio) is reduced to a ratio of (hydroxyhydroquinone / caffeoylquinic acids) ranging from approximately 0 to 0.005 by the removal treatment according to the present invention. A reduction in the concentration of caffeoylquinic acids in the entire composition by this removal treatment is small. Therefore, the present invention makes it possible to selectively remove hydroxyhydroquinone, which is a causative factor in the generation of hydrogen peroxide in the living body, without impairing the physiological effects of caffeoylquinic acids as a hypotensive effect. Examples • · · · · · Reference example 1 Assessment of the hypotensive effect An evaluation test was performed after the blood pressure of each of the 12-week-old male spontaneously hypertensive rats (SHR) was preliminarily measured for five consecutive days using a commercially available non-invasive sphygmomanometer for rats (manufactured by Softron Co., Ltd.) to accustom the rats to sphygmomanometric operation. These rats were all reared under conditions (rearing room in a rat region) of ambient temperature at 25 ± 1°C, relative humidity of 55 ± 10%, and illumination for 12 hours (from 7:00 am to 7:00 pm). A fraction obtained by removing hydroxyhydroquinone from instant coffee was administered orally to a test group, while instant coffee was administered orally to a control group. Caudal vein systolic blood pressures were measured before oral administration and 12 hours after administration, and based on these, the percentage change in blood pressure from the previous oral administration to that after 12 hours was calculated. As a result, it was found that rats to whom instant coffee without hydroxyhydroquinone had been administered showed a marked decrease in blood pressure compared to those in which instant coffee had been administered without this treatment. Reference example 2 (1) (Coffee preparation) ··· · ··· ··· • · · After uniformly dissolving 14.0 g of instant coffee in warm water to yield a total of 1000 g, the resulting solution was cooled to prepare 1000 g of coffee extract. (2) Caffeoylquinic acid (CQA) analysis method The caffeoylquinic acid content in the composition is analyzed as described below. HPLC was employed as an analytical instrument. Model number of units that make up the instrument. Detector: L-7420 (product of Hitachi, Ltd.), oven: Model 554 (product of GL Sciences), pump: L-7100 (product of Hitachi, Ltd.), autosampler: L-7200 (product of Hitachi, Ltd.), interface: D-7000 (product of Hitachi, Ltd.), column: Inertsil ODS-2, 2.1 mm internal diameter x 250 mm length (product of GL Sciences). Analysis conditions Sample injection quantity: 10 qL, flow rate: 0.3 mL / min, UV absorbance detection wavelength: 325 nm (caffeoylquinic acids), eluent A: a 3% vol. acetonitrile solution containing 0.05M acetic acid (2.86 mL acetic acid / 970 mL distilled water / 30 mL acetonitrile (v / v / v)), eluent B: a 100% vol. acetonitrile solution containing 0.05 M acetic acid (2.86 mL acetic acid / 1000 mL acetonitrile (v / v)). Concentration gradient conditions Time Eluent A Eluent B 0 minute 100% 0% 20 minutes 80% 20% 35 minutes 80% 20% 45 minutes 0% 100% 60 minutes 0% 100% 70 minutes 100% 0% 120 minutes 100% 0% The retention time of caffeoylquinic acids (unit: minute) (A1) monocaffeoylquinic acid: three points in total of 17.9, 20.4 and 22.0 (A2) dicaffeoylquinic acid: three points in total of 32.3, 33.0 and 35.8. From the area determined here, the caffeoylquinic acid content (% by mass) was determined using 5-caffeoylquinic acid as a standard substance. (3) Hydroxyhydroquinone (HHQ) analysis method The hydroxyhydroquinone content in the composition was analyzed as described below. HPLC was employed as an analytical instrument. Model number of units constituting the instrument Detector: L-7420 (product of Hitachi, Ltd.), oven: Model 554 (product of GL Sciences), pump: L-7100 (product of Hitachi, Ltd.), autosampler: L-7200 (product of φφφ φ φφφ ··· Hitachi, Ltd.), interface: D-7000 (product of Hitachi, Ltd.), column: Inertsil ODS-2, 4.6 mm internal diameter x 250 mm length (product of GL Sciences). Analysis conditions Sample injection quantity: 30 μE, flow rate: 1.0 mL / min, UV absorber detection wavelength: 288 nm (hydroxyhydroquinone), eluent A: a 0.05 M aqueous solution of acetic acid (2.86 mL of acetic acid / 1000 mL of distilled water (v / v)), eluent B: a 0.05 M acetonitrile solution of acetic acid (2.86 mL of acetic acid / 1000 mL of acetonitrile (v / v)). Concentration gradient conditions Eluent Time Eluent 0 minute 100% 0% 15 minutes 100% 0% 25 minutes 0% 100% 30 minutes 0% 100% 40 minutes 100% 0% 50 minutes 100% 0% Hydroxyquinone retention time (unit: minute): 6.5 minutes. From the area determined at 15 qui, the hydroxyquinone content (% by mass) was determined using hydroxyquinone as a standard substance. Reference example 3 In a manner similar to Reference Example 2, 14.0 0 g of instant coffee was dissolved evenly in warm water to provide a total quantity of 1000 g, followed by « * Λ 999 By cooling, 1000 g of a coffee extract was prepared. Caffeoylquinic acid (CQA) and hydroxyhydroquinone (HHQ) analyses were conducted as in Reference Example 1. Reference example 4 Coffee beans of two different Robusta species with varying degrees of roasting (L values: 16 and 22) were ground, and then coffee extracts were prepared using the conventional method. The concentrations of caffeoylquinic acid (CQA) and hydroxyhydroquinone (HHQ) in each of the resulting coffee extracts were analyzed according to the method described in Reference Examples 2 and 3. Table 1 Degree of roasting Components Concentration (mg / mL) HHQ / QAC L=22 QAC 1.0761 0.0150 HHQ 0.0161 L=16 QAC 0.1742 0.1191 HHQ 0.0207 It is understood from Table 1 that the ratio (hydroxyhydroquinone / caffeoylquinic acids) of the coffee extract having a roasting degree L of 22 is lower than that of the coffee extract having a roasting degree L of 16. Example 1 A solution treated with white clay 1 was obtained by placing 14.0 g of an acidic clay (Mizuka Ace no. 200, a 5% suspension having pH 7.6) having a S1O2 / Al2O3 ratio of 4.9 in contact with 200 g of coffee extract ob12 » · · · as determined by the operation described in Reference Example 1 at room temperature for 30 minutes, and then removing the acidic clay by filtration under reduced pressure. Solutions treated with white clay 2, 3 and 4 were then obtained, respectively, by placing 14.0% g of acid clays having a SiO2 / Al2O3 ratio of 4.3, 4.8 and 5.0 in contact with 200 g of coffee extract obtained by the operation of Reference Example 1 at room temperature for 30 minutes, and then removing the acid clays by filtration under reduced pressure. At the same time, the amounts of caffeoylquinic acids (CQA) and hydroxyhydroquinone (HHQ) in each of the solutions obtained above were analyzed as in Reference Example 1. Comparative example 1 Comparative treated solutions 1 and 2 were prepared, respectively, by placing acid clays having a SiO2 / Al2O3 ratio of 9.2 and 6.8 (their pHs, as a 5% suspension: 3.4 and 3.6 respectively) in contact with 200 g of coffee extract obtained from the operation of Reference Example 2 at room temperature for 30 minutes, and then removing the acid clays by filtration under reduced pressure. At the same time, the amounts of caffeoylquinic acids (CQA) and hydroxyhydroquinone (HHQ) were analyzed as in Reference Example 1. « · * * • « • · • · · • • • • • • • • • • ·· tf • · • ·· « • • · · • • 4 • 9 9 9 · ··* • 9 * • ·· • • · · • • • · « 9 • * Table 2 Quantity of white clay SiOz / AlA HHQ (% by mass) CQA (% by mass) HHQ / CQA Reference example 1 None - 0.0104 0.4849 0.0214 Solution treated with white clay 1 7.0% 4.9 0 0.4424 0.0000 Solution treated with white clay 2 7.0% 4.8 0.0002 0.4627 0.0004 Solution treated with white clay 3 7.0% 4.3 0.0002 0.4670 0.0004 Solution treated with white clay 4 7.0% 5.0 0.0017 0.3971 0.0042 Reference example 2 None - 0.0157 0.5172 0.0304 Comparative treated solution 1 7.0% 9.2 0.0045 0.4586 0.0099 Comparative treated solution. 2 7.0% 6.8 0.0042 0.4996 0.0085 SiO2 / Al2O3 ratio: mass ratio after drying. 110°C • · • tf tftf ··· < tftf* • · » · 9 · tf · tf C · • tf · tftf •y tf · · • · · · · • tf · · O · tf • tf • • · tf tf ··· ·«· Table 2 showed that when acidic clay with a SiO2 / Al2O3 ratio of 3 to 5 was used, the reduction in the concentration of caffeoylquinic acids was small, and only hydroxyhydroquinone could be selectively removed. It was also observed that when acidic clay with a SiO2 / Al2O3 ratio exceeding 5 was used, the removal rate of hydroxyhydroquinone was lower. φφφ *ι > φ η φ · *» 7 · • -Λ · · · · φ φ · ΦΦΦ· • Φ Φ · * · Φ Φ Φ Φ Φ Φ Φ · *>φ · Φ ··· ··· Φ Φ Φ · ΦΦ Φ φ ΦΦ ·· Φ ΦΦ· · · φ Φ Φ Φ Φ Φ · Φ Φ Φ Φ ·

Claims

CLAIMS 1. A method for removing hydroxyhydroquinone from an aqueous solution containing hydroxyhydroquinone and caffeoylquinic acids, CHARACTERIZED by comprising step 5 of contacting the aqueous solution with an acidic clay having an S1O2 / Al2O3 ratio of 3 to 4.

2. Method of removing hydroxyhydroquinone, according to claim 1, CHARACTERIZED in that the aqueous solution containing hydroxyhydroquinone and ca10 pheoylquinic acids is a coffee bean extract having a roasting degree (L value) of 18 or more.

3. Aqueous solution containing caffeoylquinic acid, CHARACTERIZED by having a mass ratio of hydroxyhydroquinone / caffeoylquinic acids of 0 to 0.05, which is provided by the method according to claim 1 or 2.