JP6704713B2 - Method for producing roasted coffee beans - Google Patents

Description

The present invention relates to a method for producing roasted coffee beans.

The coffee beverage contains chlorogenic acids such as chlorogenic acid, caffeic acid, and ferulic acid, which are a kind of polyphenol, and chlorogenic acids are known to have excellent physiological activity such as antihypertensive action. However, it has been reported that when roasted green coffee beans generate hydroxyhydroquinone, and this hydroxyhydroquinone inhibits the physiological action of chlorogenic acids. Therefore, in order to fully express the physiological effects of chlorogenic acids, it is advantageous to use roasted coffee beans that are rich in chlorogenic acids and that contain hydroxyhydroquinone as much as possible. Therefore, as a method for producing roasted coffee beans in which hydroxyhydroquinone is reduced, for example, a method in which raw material roasted coffee beans having an L value of 30 to 50 are housed in a closed container and subjected to heat treatment at 100 to 160° C. It has been proposed (Patent Document 1), and Patent Document 1 describes that it is particularly preferable that the inside of the sealed container before the heat treatment is under an air atmosphere. A method has also been proposed in which raw roasted coffee beans are immersed in an aqueous solvent to extract hydroxyhydroquinone from the raw roasted coffee beans (Patent Document 2).

Further, coffee beverages are widely popular as favorite beverages, and roasted coffee beans useful as a raw material for coffee beverages having a good flavor are demanded. For example, in order to obtain a good flavor, green coffee beans are roasted to L33 to 60, and the obtained roasted coffee beans are treated with an aqueous alkaline solution at a temperature of 4 to 288° C. for 3 seconds to 48 hours. , And more preferably, a method of roasting to L16 to 24 has been proposed (Patent Document 3). Further, in order to obtain a coffee extract with suppressed sourness, roasted coffee beans are sprayed with an alkaline solution having a concentration of 1.0 to 2.0 M/L by 0.5 to 5.0% based on the weight of the beans. A method has been proposed (Patent Document 4). Further, it has also been reported that the alkali treatment of roasted coffee beans can prevent the aggregation and precipitation of milk components after heat sterilization (Patent Document 5). However, these documents make no mention of reduction of hydroxyhydroquinone in roasted coffee beans.

JP2012-183035A JP 2008-178399A European Patent Application Publication No. 0217957 JP-A-2005-52024 JP-A-11-313647

In order to develop roasted coffee beans useful as a raw material for coffee beverages that can be expected to have physiological effects due to chlorogenic acids, the present inventors heat-treat the roasted coffee beans as a raw material in the atmosphere to reduce hydroxyhydroquinone. When the roasted coffee beans thus prepared were manufactured, it was found that a strange taste may be felt when the roasted coffee beans extract is drunk in a cold state. An object of the present invention is to provide a method for producing roasted coffee beans useful as a raw material for coffee beverages, which selectively reduces hydroxyhydroquinone without impairing chlorogenic acids, and which suppresses the off taste when cooled. It is in.

The present inventors, as a result of studies in view of the above problems, when the roasted coffee beans are produced by heat-treating the raw roasted coffee beans under a fluid atmosphere in which the oxygen concentration is reduced, when the roasted coffee beans are It has been found that it is possible to suppress the off taste when the extract is drunk in a cold state. On the other hand, it has been found that such roasted coffee beans are less likely to reduce hydroxyhydroquinone than roasted coffee beans produced by heating raw roasted coffee beans in an air atmosphere.
As a result of further studies, the present inventors have added a small amount of an aqueous alkaline solution to the raw roasted coffee beans, and then added the roasted raw coffee beans to the raw roasted coffee beans at a predetermined temperature in a fluid atmosphere with a reduced oxygen concentration. Roasted coffee beans useful as a raw material for coffee beverages that retain a state of contact with an alkaline aqueous solution, selectively reduce hydroxyhydroquinone without damaging chlorogenic acids, and suppress the off-taste when cooled. It was found that

That is, in the present invention, after adding an alkaline aqueous solution of 5 to 110 mass% to the raw roasted coffee beans to the raw roasted coffee beans, the oxygen concentration is 5 to 5% by volume in a fluid atmosphere. The present invention provides a method for producing roasted coffee beans, which is maintained at 150°C.

According to the present invention, roasted coffee beans useful as a raw material for coffee beverages that selectively reduce hydroxyhydroquinone without damaging chlorogenic acids, and have a suppressed off-flavor when cooled are efficiently produced by a simple operation. It can be manufactured. Further, the roasted coffee beans obtained by the production method of the present invention contain abundant chlorogenic acids and have reduced hydroxyhydroquinone. Therefore, the physiological effects of chlorogenic acids can be expected sufficiently. Therefore, the roasted coffee beans obtained by the production method of the present invention are useful as a raw material for a coffee beverage to be continuously ingested for a long period of time.

The method for producing roasted coffee beans according to the present invention comprises the steps of adding an alkaline aqueous solution of 15 to 110% by mass to the raw roasted coffee beans to the raw roasted coffee beans, and then adding a fluid having an oxygen concentration of 0 to 8% by volume. It is held at 5 to 150° C. in the atmosphere.

Examples of the bean type of the raw roasted coffee beans include Arabica type, Robusta type, Reberica type, Arabus type and the like. In addition, the production area of coffee beans is not particularly limited, and examples thereof include Brazil, Colombia, Tanzania, Mocha, Kilimanjaro, Mandolin, Blue Mountain, Guatemala, Vietnam, Indonesia, and the like.

The raw roasted coffee beans may be roasted green coffee beans or a commercially available product. The roasting method of green coffee beans is not particularly limited, and a known method can be appropriately selected. For example, the roasting temperature is preferably 180 to 300° C., more preferably 190 to 280° C., further preferably 200 to 280° C., and the heating time can be appropriately set so that a desired roasting degree can be obtained. is there. As the roasting device, for example, a roasted bean stationary type, a roasted bean transfer type, a roasted bean stirring type, or the like can be used. Specific examples include a shelf dryer, a conveyor dryer, a rotary drum dryer, a rotary V dryer, and the like. Examples of the heating method include an open flame type, a hot air type, a semi-hot air type, a far infrared ray type, an infrared ray type, a microwave type, and a superheated steam type.

From the viewpoint of the content of chlorogenic acids and the flavor, the L value of the raw roasted coffee beans is preferably 15 or more, more preferably 17 or more, further preferably 20 or more, and preferably 45 or less, more preferably 40 or less, 35 or less are more preferable, and 33 or less are still more preferable. The range of the L value is preferably 15 to 45, more preferably 17 to 40, further preferably 20 to 35, still more preferably 20 to 33. Here, the "L value" in the present specification means that the lightness of roasted coffee beans is measured by a color difference meter, with black having an L value of 0 and white having an L value of 100. As the color difference meter, for example, Spectrophotometer SE2000 (manufactured by Nippon Denshoku Co., Ltd.) can be used.

As the raw material roasted coffee beans, one kind or two or more kinds can be used. When using two or more types of roasted coffee beans as raw materials, it is possible to use not only coffee beans of different bean types and production areas but also coffee beans of different roasting degrees. When coffee beans having different roasting degrees are used, those having an L value outside the above range may be used, but it is preferable to use the coffee beans in an appropriate combination so that the average L value is within the above range. The average value of the L value is obtained as the sum of the values obtained by multiplying the L value of the raw roasted coffee beans to be used by the content mass ratio of the raw roasted coffee beans.

The raw roasted coffee beans may be unground or ground. The method for crushing the raw roasted coffee beans is not particularly limited, and known methods and devices can be used. For example, in addition to a mallet, a hammer, a cutter mill, a hammer mill, a jet mill, an impact mill, a Willey crusher. And the like.

The average particle size of the ground roasted coffee beans is preferably 5 mm or less, more preferably 2.5 mm or less, further preferably 1.5 mm or less, and further preferably 0.9 mm or less, from the viewpoint of reducing hydroxyhydroquinone. From the viewpoint of production efficiency, 0.001 mm or more is preferable, 0.01 mm or more is more preferable, 0.05 mm or more is further preferable, and 0.1 mm or more is even more preferable. The range of the average particle size is preferably 0.001 to 5 mm, more preferably 0.01 to 2.5 mm, still more preferably 0.05 to 1.5 mm, still more preferably 0.1 to 0.9 mm. Is. In the present specification, the “average particle size” is a particle size corresponding to 50% (d ₅₀ ) in a volume-based cumulative particle size distribution curve measured by a laser diffraction/scattering particle size distribution measuring device. It is also possible to perform classification so that the average particle diameter falls within the above range using a Tyler standard sieve, ASTM standard sieve, JIS standard sieve, or the like, and the desired average particle diameter is determined by the laser diffraction/scattering particle size distribution. Even when it is outside the measurement range of the measuring device, classification can be performed using the above-mentioned sieve.

In the manufacturing method of the present invention, first, an alkaline aqueous solution is added to the raw roasted coffee beans.
As the alkaline aqueous solution, it is possible to use one prepared by dissolving an alkali in water. Examples of the alkali include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, hydroxides of alkaline earth metals such as magnesium hydroxide, calcium hydroxide and barium hydroxide, sodium carbonate and potassium carbonate. Alkaline metal carbonates, magnesium carbonate, calcium carbonate, barium carbonate and other alkaline earth metal carbonates, sodium hydrogen carbonate, potassium hydrogen carbonate and other alkali metal hydrogen carbonates, magnesium hydrogen carbonate, calcium hydrogen carbonate, carbonic acid Examples thereof include hydrogencarbonates of alkaline earth metals such as barium hydrogen, ammonium carbonate, ammonium hydrogencarbonate, ammonia, tetraalkylammonium hydroxide, hydrazine and the like. Among them, from the viewpoint of reducing hydroxyhydroquinone, a hydroxide of an alkali metal or an alkaline earth metal, a carbonate of an alkali metal or an alkaline earth metal, a hydrogen carbonate of an alkali metal or an alkaline earth metal is preferable, and a carbonate of an alkali metal. Salts, alkaline earth metal carbonates, alkali metal hydrogencarbonates and alkaline earth metal hydrogencarbonates are more preferable, and alkali metal hydrogencarbonates are still more preferable. The alkali can be used alone or in combination of two or more. Further, the alkali used does not have to be a pure substance or a combination thereof, and a substance containing a substance exhibiting alkalinity as a component can be appropriately used. For example, crude baking soda, alkaline ionized water, ash and the like can be used as appropriate.
Examples of the raw material water used when preparing the alkaline aqueous solution include tap water, distilled water, ion-exchanged water, natural water, alkaline ionized water, and the like. Further, an aqueous solution in which an alkali is dissolved may be used as raw material water.

The alkali concentration in the alkaline aqueous solution can be appropriately selected depending on the alkali species, but from the viewpoint of reducing hydroxyhydroquinone, it is preferably 0.005% by mass or more, more preferably 0.05% by mass or more, and 0.5% by mass. % Or more, more preferably 50% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less, from the viewpoint of the amount of chlorogenic acids recovered. The range of the alkali concentration in the aqueous alkali solution is preferably 0.005 to 50% by mass, more preferably 0.05 to 30% by mass, and further preferably 0.5 to 20% by mass.

The pH of the aqueous alkali solution (20° C.) is usually 7.0 or higher, but from the viewpoint of reducing hydroxyhydroquinone, it is more preferably 7.3 or higher, further preferably 7.5 or higher, and 13. from the viewpoint of safety. 0 or less is preferable, 11.5 or less is more preferable, 10.5 or less is further preferable, and 9.5 or less is even more preferable. The pH range is preferably 7.0 to 13.0, more preferably 7.3 to 11.5, still more preferably 7.3 to 10.5, still more preferably 7.5 to 9.5. Is.

The method for adding the alkaline aqueous solution is not particularly limited, and for example, a method of directly adding the alkaline aqueous solution to the raw roasted coffee beans, a method of spraying the alkaline aqueous solution, or a method of passing the raw roasted coffee through the alkaline aqueous solution. After that, a method of taking out roasted coffee beans can be mentioned. Further, the raw roasted coffee beans may be stirred and mixed after the addition of the alkaline aqueous solution or while adding the alkaline aqueous solution. You may perform the process of pressurizing or depressurizing, or the process of heating, adding the alkaline aqueous solution to the raw material roasted coffee beans, or after adding. In particular, when unmilled roasted coffee beans are used as the raw roasted beans, it is preferable to perform one or more of these treatments in order to allow the aqueous alkali solution to penetrate into the roasted raw coffee beans.

The amount of the alkaline aqueous solution added does not have to be an amount sufficient to extract the hydroxyhydroquinone from the raw roasted coffee beans by immersing the raw roasted coffee beans in the alkaline aqueous solution. The amount may be such that the parts can be brought into contact with the alkaline aqueous solution. Specifically, the addition amount of the alkaline aqueous solution is 5 to 110% by mass with respect to the raw roasted coffee beans, but from the viewpoint of reducing hydroxyhydroquinone, 10% by mass or more with respect to the raw roasted coffee beans. 20 mass% or more is more preferable, 30 mass% or more is still more preferable, 40 mass% or more is still more preferable, and from the viewpoint of preventing the elution of chlorogenic acids, 108 mass% or less is preferable, and 105 mass% or less is further. preferable. The addition amount of the alkaline aqueous solution is preferably 10 to 110% by mass, more preferably 20 to 110% by mass, further preferably 30 to 108% by mass, and still more preferably 40% with respect to the raw roasted coffee beans. Is about 105% by mass.

The total amount of the alkaline aqueous solution may be added continuously or in a plurality of times.
Further, the temperature at the time of adding the alkaline aqueous solution is preferably close to the temperature to be held as described later, but from the viewpoint of ease of temperature adjustment, it is preferably 10 to 100°C, more preferably 15 to 70°C, and further The temperature is preferably 18 to 50°C, more preferably 18 to 25°C.

Next, the raw roasted coffee beans in contact with the alkaline aqueous solution are held at 5 to 150° C. in a fluid atmosphere having an oxygen concentration of 8% by volume or less. Here, in the present specification, “holding” means keeping the raw roasted coffee beans at a constant temperature or maintaining the temperature within a range of 5 to 150° C. while changing the temperature with time. The extraction operation of obtaining a coffee extract from roasted coffee beans using an extraction solvent is not included. In the holding step, the decomposition reaction and/or the polymerization reaction of hydroxyhydroquinone in the raw roasted coffee beans are accelerated or aged, so that the hydroxyhydroquinone in the raw roasted coffee beans is reduced.
Further, in the present specification, the term “fluid” refers to a continuum that does not generate shear stress in a stationary state, and examples of its form include gas fluid, supercritical fluid, plasma, and combinations thereof. Among them, gas fluid, supercritical fluid, and mixed fluid of gas fluid and supercritical fluid are preferable from the viewpoint of preventing elution of chlorogenic acids from roasted coffee beans. Here, “normal temperature and normal pressure” means 25° C.±5° C. and 101325±1000 Pa. Further, the "supercritical fluid" means a special fluid that is in a state of exceeding the temperature and pressure (critical point) at which gas and liquid can coexist and exhibits properties different from those of ordinary gas and liquid. For example, supercritical carbon dioxide has a critical temperature of 31° C. and a critical pressure of 7.38 MPa, and supercritical nitrogen has a critical temperature of −147° C. and a critical pressure of 3.35 MPa.

Examples of the gas fluid include inert gas, and examples of the inert gas include nitrogen gas, carbon dioxide gas, and rare gas. Examples of the rare gas include helium, neon, argon, krypton, xenon, and radon. Further, it is not necessary to use only a substance that is a gas at normal temperature and normal pressure as a gas fluid, and for example, vapor of a substance that is a liquid at normal temperature and normal pressure can be used. Examples of vapors of substances that are liquid at room temperature and atmospheric pressure include vapors of water, organic solvents, milk, tea, fruit juice, vegetable juice, liquor and the like. Examples of the organic solvent include ethanol and acetic acid. Of these, one or more kinds of steam selected from water, ethanol, acetic acid, milk, tea, fruit juice, vegetable juice and sake are preferable. The gas fluid may be used alone or in combination of two or more.
Examples of the supercritical fluid include supercritical nitrogen, supercritical carbon dioxide, supercritical ethanol, supercritical dimethyl ether, supercritical ethane, and supercritical ethylene. Among them, from the viewpoint of work efficiency, one or more selected from supercritical nitrogen, supercritical carbon dioxide, supercritical ethanol and supercritical dimethyl ether are preferable, and at least selected from supercritical nitrogen and supercritical carbon dioxide. One kind is more preferable.
The holding step can be performed by appropriately selecting atmospheric pressure, pressurization or depressurization depending on the type of fluid.

To keep the raw roasted coffee beans after contact with the alkaline aqueous solution in a fluid atmosphere, for example, the raw roasted coffee beans are stored in a container, and a fluid whose oxygen concentration is controlled is aerated in the container. Good. The fluid whose oxygen concentration is controlled is, for example, an inert gas cylinder, and if necessary, a pressure regulator is installed in the oxygen cylinder, and the pressure and flow rate are adjusted so that the desired oxygen concentration is obtained, and the fluid is supplied into the container. Good. A glass tube, a metal column, or the like can be appropriately selected as the container.
Further, after replacing the gas phase in the container with a fluid having a controlled oxygen concentration, the raw roasted coffee beans may be housed in the container and the container may be sealed. The replacement of the gas phase in the closed container is, for example, after replacing the gas phase in the container in a glove box in which the oxygen concentration is controlled, the raw roasted coffee beans are contained in the container, and the opening of the container is opened. Should be sealed. Alternatively, a container containing the raw roasted beans may be sealed with a fluid containing oxygen and then sealed, and then the oxygen in the container may be reduced by reaction, adsorption or the like. The closed container is not particularly limited in shape and material as long as it can block the flow of gas, but a container that does not deteriorate by heating and can withstand pressurization or depressurization is preferable, and examples thereof include a metal container and a glass container. be able to. Specific examples of the closed container include, for example, a retort pouch, a can, a bottle, a beaker, and the like, and the can, the pin, and the beaker are preferably those that can be closed with a stopper or a lid and can be opened and closed.

The oxygen concentration in the fluid is 8% by volume or less, but from the viewpoint of reducing the odd taste when cooled, 6% by volume or less is preferable, 4% by volume or less is more preferable, and 2% by volume or less is further preferable. The lower limit of the oxygen concentration in the fluid is not particularly limited and may be 0% by volume.

The holding temperature is 5 to 150°C, but from the viewpoint of reducing hydroxyhydroquinone, it is preferably 20°C or higher, more preferably 35°C or higher, further preferably 55°C or higher, further preferably 70°C or higher, and chlorogen. From the viewpoint of suppressing decomposition of acids and production efficiency, 145°C or lower is preferable, 140°C or lower is more preferable, 135°C or lower is further preferable, and 130°C or lower is further preferable. The range of the holding temperature is preferably 20 to 145°C, more preferably 35 to 140°C, further preferably 55 to 135°C, and further preferably 70 to 130°C.

From the viewpoint of reducing hydroxyhydroquinone, the holding time is preferably 10 minutes or longer, more preferably 15 minutes or longer, further preferably 20 minutes or longer, and preferably 1000 minutes or shorter, more preferably 600 minutes or shorter, and further 400 minutes or shorter. It is more preferably 200 minutes or less, still more preferably 60 minutes or less. The range of the holding time is preferably 10 to 1000 minutes, more preferably 15 to 600 minutes, further preferably 15 to 400 minutes, further preferably 15 to 200 minutes, still more preferably 15 to 60 minutes, still more preferably Is 20-60 minutes. The holding time here is the elapsed time from the storage of the raw roasted coffee beans in the device when using a device whose temperature is controlled in advance, and the raw roasted coffee beans are stored in the device. When the temperature is set after the housing, it is the elapsed time after reaching the predetermined temperature.

The holding time can be appropriately selected depending on the holding temperature. For example, when the holding temperature is 5°C or higher and lower than 70°C, the holding time is preferably 20 to 1000 minutes, more preferably 20 to 600 minutes, and more preferably 20 to 600 minutes. 200 minutes is more preferred. When the holding temperature is 70 to 150° C., the holding time is preferably 15 to 200 minutes, more preferably 15 to 60 minutes, still more preferably 20 to 60 minutes.

After the holding step, the roasted coffee beans of the present invention can be obtained by taking out the roasted coffee beans from the apparatus. When heat-treated in the holding step, the roasted coffee beans may be cooled. Further, the roasted coffee beans may be dried after the holding step, and examples of the drying method include a method of drying using a blower fan, a method of drying under reduced pressure, a method of freeze-drying, and the like. The water content of the dried roasted coffee beans is preferably 30% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, and further preferably 5% by mass or less. The water content can be measured by the atmospheric pressure heating and drying method. For example, about 1 g of a sample is weighed, heat-treated at 105° C. for 6 hours, the sample after the heat treatment is weighed, and the mass of the sample before and after the heat treatment can be calculated. Specifically, it can be calculated using the following formula.

Moisture content (mass %)=([mass of coffee beans before heat treatment (g)]-[mass of coffee beans after heat treatment (g)])/[mass of coffee beans before heat treatment (g)] ×100

The roasted coffee beans thus obtained can have the following characteristics.
(1) From the viewpoint of physiological effects, the content of hydroxyhydroquinone in roasted coffee beans is preferably 60 mg or less, more preferably 50 mg or less, still more preferably 40 mg or less, particularly preferably 30 mg or less, per 1 kg of roasted coffee beans. preferable. The lower limit of the content of such hydroxyhydroquinone is not particularly limited, and may be 0 mg per 1 kg of roasted coffee beans. The content of hydroxyhydroquinone of 0 mg is a concept that also includes the case where the content of hydroxyhydroquinone is below the detection limit in the “Analysis of hydroxyhydroquinone” described in Examples below.
(2) The content of chlorogenic acids in the roasted coffee beans is preferably 10 g or more, more preferably 20 g or more, still more preferably 30 g or more, and flavor of 1 kg of roasted coffee beans from the viewpoint of enhancing physiological effects. From the viewpoint, 50 g or less is preferable, 45 g or less is more preferable, and 40 g or less is further preferable. The content range of such chlorogenic acids is preferably 10 to 50 g, more preferably 20 to 45 g, and further preferably 30 to 40 g per 1 kg of roasted coffee beans. Here, in the present specification, “chlorogenic acids” means monocaffeoylquinic acid of 3-caffeoylquinic acid, 4-caffeoylquinic acid and 5-caffeoylquinic acid, and 3-ferulaquinaic acid, 4-ferulaquina. Acid and 5-ferulaquinic acid are generic terms that collectively refer to monoferulaquinic acid, and in the present invention, at least one of the above six types of chlorogenic acids may be contained. The content of chlorogenic acids is defined based on the total amount of the above 6 types.

In the present specification, "hydroxyhydroquinone content in roasted coffee beans" and "chlorogenic acid content in roasted coffee beans" means hydroxyhydroquinone content in a coffee extract obtained from roasted coffee beans. And the following formulas (i) to (ii) based on the content of chlorogenic acids.

(I) Hydroxyhydroquinone content in roasted coffee beans (mg/100g)=[hydroxyhydroquinone content in coffee extract (mg/100g)]×[mass of coffee extract (g)]/[roasting Mass of coffee beans (g)]
(Ii) Chlorogenic acid content in roasted coffee beans [mg/100g] = [chlorogenic acid content in coffee extract (mg/100g)] x [mass of coffee extract (g)]/[roasting] Mass of coffee beans (g)]

The analysis conditions for the coffee extract are as follows. 80 g of extraction water (1 g of phosphoric acid and 0.03 g of 1-hydroxyethane-1,1-diphosphonic acid (HEDPO) dissolved in 1 L of ion-exchanged water) was added to 0.8 g of ground roasted coffee beans, and 95 Immersion extraction is carried out for 10 minutes while maintaining the temperature between 99°C. Next, the supernatant of the coffee extract is collected and subjected to the method described in Examples below to analyze the content of hydroxyhydroquinone and the content of chlorogenic acids.

1. Analysis of roasted coffee beans 0.5 g of ground roasted coffee beans was charged with extraction water [1 g of phosphoric acid and 0.03 g of 1-hydroxy-1,1-diphosphonic acid (HEDPO) dissolved in 1 L of ion-exchanged water]. 80 g was added and immersion extraction was performed for 10 minutes while maintaining the temperature at 95 to 99° C., and the supernatant was collected to obtain a coffee extract. Based on the obtained coffee extract, roasted coffee beans were analyzed.

2. Analysis of Hydroxyhydroquinone (HHQ) by HPLC-Electrochemical Detector As an analytical instrument, a couloarray system (model 5600A, manufactured by ESA, USA) which is an HPLC-electrochemical detector (coulometric type) was used. The names and model numbers of the constituent units of the device are as follows.
・Analytical cell: Model 5011 (ESA)
・Curo Array Electronics Module ・Software: Coulochem III (ESA)
・Solvent delivery pump: LC-20AD (manufactured by Shimadzu Corporation), inert mixer 20A (manufactured by Shimadzu Corporation)
・Autosampler: SIL-20AC (manufactured by Shimadzu Corporation), peak pulse damper,
・Degasser: DGU-20A-5 (manufactured by Shimadzu Corporation)
・Column oven: CTO-20AC
・Column: CAPCELL PAK C18 AQ, inner diameter 4.6 mm×length 250 mm, particle diameter 5 μm (Shiseido Co., Ltd.)

The analysis conditions are as follows.
・Sample injection volume: 10 μL
・Flow rate: 1.0 mL/min
-Applied voltage for electrochemical detector: 200 mV
・Column oven set temperature: 40℃
Eluent A: 0.1 (W/V)% phosphoric acid, 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid, 5 (V/V)% methanol solution Eluent B: 0.1( W/V)% phosphoric acid, 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid, 50 (V/V)% methanol solution

To prepare the eluents A and B, distilled water for high performance liquid chromatography (manufactured by Kanto Chemical Co., Inc.), methanol for high performance liquid chromatography (manufactured by Kanto Chemical Co., Ltd.), phosphoric acid (special grade, manufactured by Wako Pure Chemical Industries, Ltd.), 1-Hydroxyethane-1,1-diphosphonic acid (60% aqueous solution, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

Concentration gradient condition (volume%)
Time Eluent A Eluent B
0.0 minutes 100% 0%
10.0 minutes 100% 0%
10.1 minutes 0% 100%
20.0 minutes 0% 100%
20.1 minutes 100% 0%
50.0 minutes 100% 0%

4 mL of the coffee extract was passed through Bond Elute SCX (solid-phase filling amount: 500 mg, reservoir volume: 3 mL, manufactured by Agilent Technologies), and about 0.5 mL of the first passing liquid was removed to obtain a passing liquid. About 2 mL of this passing liquid was filtered with a membrane filter (GL Chromatodisc 25A, pore size 0.45 μm, manufactured by GL Science) and immediately subjected to analysis.

In the analysis under the above conditions of the HPLC-electrochemical detector, the retention time of hydroxyhydroquinone was 6.3 minutes. From the area value of the obtained peak, the hydroxyhydroquinone content (mg/kg) was determined using hydroxyhydroquinone (manufactured by Wako Pure Chemical Industries, Ltd.) as a standard substance.

3. Analysis of chlorogenic acids (CGA) HPLC was used as an analytical instrument. The model numbers of the constituent units of the device are as follows.
・UV-VIS detector: SPD20A (manufactured by Shimadzu Corporation)
・Column oven: CTO-20AC (manufactured by Shimadzu Corporation)
・Pump: LC-20AT (manufactured by Shimadzu Corporation)
・Auto sampler: SIL-20AC (manufactured by Shimadzu Corporation)
・Column: Cadenza CD-C18 inner diameter 4.6 mm×length 150 mm, particle diameter 3 μm (Intact)
・Degasser: DGU-20A-5 (manufactured by Shimadzu Corporation)

The analysis conditions are as follows.
・Sample injection volume: 10 μL
・Flow rate: 1.0 mL/min
・UV-VIS detector setting wavelength: 325 nm
・Column oven set temperature: 35℃
Eluent C: 0.05 M acetic acid, 0.1 mM HEDPO, 10 mM sodium acetate, 5 (V/V)% acetonitrile solution Eluent D: acetonitrile

Concentration gradient condition (volume%)
Time Eluent C Eluent D
0.0 minutes 100% 0%
10.0 minutes 100% 0%
15.0 minutes 95% 5%
20.0 minutes 95% 5%
22.0 minutes 92% 8%
50.0 minutes 92% 8%
52.0 minutes 10% 90%
60.0 minutes 10% 90%
60.1 minutes 100% 0%
70.0 minutes 100% 0%

In HPLC, the coffee extract was filtered through a membrane filter (GL Chromatodisc 25A, pore size 0.45 μm, manufactured by GL Sciences Inc.) and then subjected to analysis.
Retention time of chlorogenic acids (unit: minutes)
・Monofafe oil quinic acid: 5.3, 8.8, 11.6, 3 points in total ・Monoferuraquinic acid: 13.0, 19.9, 21.0, 3 points in total From the area value of chlorogenic acids, the content (mass%) of chlorogenic acids was determined using 5-caffeoylquinic acid as a standard substance.

4. Measurement of L value The sample was measured using a color difference meter (Spectrophotometer SE2000, manufactured by Nippon Denshoku Co., Ltd.).

5. Sensory evaluation The roasted coffee beans obtained in Examples and Comparative Examples were crushed with a crusher (made by Karita Co., Ltd.) to an average particle size of 1.5 mm. To 5 g of the obtained ground roasted coffee beans, 100 g of hot water at 98 to 100° C. was added, stirred for 5 minutes, and then filtered with a commercially available coffee paper filter. The obtained extract was cooled to 26°C at room temperature. With respect to the coffee drink in this chilled state, four panelists sensory evaluated the unpleasant off-taste strength which was not the original flavor of coffee. The strength of the off-taste was evaluated based on the evaluation criteria shown below, and the final score was determined after consultation with four people.

Evaluation criteria for the strength of the off-flavor when cooled: 1: Does not feel the off-flavor 2: Feels the slightly off-flavor 3: Feels the off-flavor 4: Feels a slightly strong off-flavor 5: Feels the strong off-flavor

Example 1
Roasted L30 unbranched coffee beans of Vietnam's Robusta species are weighed in an amount of 10 g in an aluminum alloy container having an internal capacity of 190 mL, and a concentration of 5 mass% sodium bicarbonate aqueous solution (5 g of sodium bicarbonate dissolved in 95 g of deionized water). Was added. In the glove box, the gas inside the container was replaced with nitrogen gas having a purity of 99.9% or more, and then the container was sealed. This closed container was kept for 30 minutes in a thermostat heated to 120°C. After the holding, the roasted coffee beans were taken out from the closed container and dried with a freeze dryer (ALPHA2-4LSC, manufactured by Cristo) to obtain roasted coffee beans with a water content of 3% or less. Then, the obtained roasted coffee beans were analyzed based on the above-mentioned "Analysis of roasted coffee beans". The results are shown in Table 1.

Example 2
10 g of roasted coffee beans of L30, which is a Robusta species produced in Vietnam, and was roasted in a stainless steel column with an inner diameter of 1.6 cm and a height of 15 cm was dissolved in a sodium bicarbonate aqueous solution having a concentration of 5% by mass (5 g of sodium bicarbonate was dissolved in 95 g of ion-exchanged water). 10 g) was added. This column was attached to a supercritical carbon dioxide treatment device (manufactured by JASCO Corporation), and while flowing carbon dioxide (purity 99.995% or more) at a flow rate of 5 g/min, in supercritical carbon dioxide at a pressure of 30 MPa and a temperature of 120°C. Held for 30 minutes. After holding, the roasted coffee beans were taken out from the column and dried with a freeze dryer (ALPHA2-4LSC, manufactured by Christo) to obtain roasted coffee beans with a water content of 3% or less. Then, the obtained roasted coffee beans were analyzed based on the above-mentioned "Analysis of roasted coffee beans". The results are shown in Table 1.

Comparative Example 1
An unground raw material roasted coffee bean of L30 of Vietnam Robusta species was analyzed based on the above-mentioned "Analysis of Roasted Coffee Beans". The results are shown in Table 1.

Comparative example 2
Roasted coffee beans having a water content of 3% by mass or less were obtained in the same manner as in Example 1 except that ion-exchanged water was used instead of the sodium bicarbonate aqueous solution having a concentration of 5% by mass. Then, the obtained roasted coffee beans were analyzed based on the above-mentioned "Analysis of roasted coffee beans". The results are shown in Table 2 together with the results of Example 1.

Example 3
The water content was the same as in Example 1 except that the inside of the container was replaced with a nitrogen/oxygen mixed gas having an oxygen concentration of 5% by volume instead of the nitrogen gas having a purity of 99.9% or more. Roasted coffee beans of 3% by mass or less were obtained. Then, the obtained roasted coffee beans were analyzed based on the above-mentioned "Analysis of roasted coffee beans". The results are shown in Table 3 together with the results of Example 1.

Comparative Example 3
The water content was the same as in Example 1 except that the inside of the container was replaced with a nitrogen/oxygen mixed gas having an oxygen concentration of 10% by volume instead of the nitrogen gas having a purity of 99.9% or more. Roasted coffee beans of 3% by mass or less were obtained. Then, the obtained roasted coffee beans were analyzed based on the above-mentioned "Analysis of roasted coffee beans". The results are shown in Table 3 together with the results of Example 1.

Comparative Example 4
In the same manner as in Example 1, except that the inside of the container was replaced with a nitrogen/oxygen mixed gas having an oxygen concentration of 20.9% by volume instead of the nitrogen gas having a purity of 99.9% or more. Roasted coffee beans having a water content of 3 mass% or less were obtained. Then, the obtained roasted coffee beans were analyzed based on the above-mentioned "Analysis of roasted coffee beans". The results are shown in Table 3 together with the results of Example 1.

Comparative Example 5
Roasted coffee beans having a water content of 3% by mass or less were obtained in the same manner as in Example 1 except that 20 g instead of 10 g of an aqueous sodium bicarbonate solution having a concentration of 5% by mass was added. Then, the obtained roasted coffee beans were analyzed based on the above-mentioned "Analysis of roasted coffee beans". The results are shown in Table 4 together with the results of Example 1.

From Tables 1 to 4, after adding a trace amount of the alkaline aqueous solution to the raw roasted coffee beans, the mixture was kept at a predetermined temperature in a fluid atmosphere in which the oxygen concentration was reduced, so that the hydroxyhydroquinone was not damaged. It can be seen that roasted coffee beans useful as a raw material of a coffee beverage in which the taste of the coffee when cooled is suppressed can be obtained.

Claims (9)

After adding an alkaline aqueous solution of 5 to 110 mass% to the raw roasted coffee beans to the raw roasted coffee beans, the mixture is kept at 5 to 150° C. in a fluid atmosphere having an oxygen concentration of 8 vol% or less. Method for producing roasted coffee beans. The method for producing roasted coffee beans according to claim 1, wherein the holding time is 10 to 1000 minutes. The method for producing roasted coffee beans according to claim 1 or 2, wherein the alkaline aqueous solution has a pH of 7.0 to 13.0. The method for producing roasted coffee beans according to any one of claims 1 to 3, wherein the raw roasted coffee beans have an L value of 15 to 45. The method for producing roasted coffee beans according to claim 1, wherein the fluid is an inert gas. The method for producing roasted coffee beans according to claim 5, wherein the inert gas is one or more selected from nitrogen gas, carbon dioxide gas and rare gas. The method for producing roasted coffee beans according to any one of claims 1 to 4, wherein the fluid is a supercritical fluid. The method for producing roasted coffee beans according to claim 7, wherein the supercritical fluid is one or more selected from supercritical nitrogen, supercritical carbon dioxide, supercritical ethanol, and supercritical dimethyl ether. The method for producing roasted coffee beans according to any one of claims 1 to 4, wherein the fluid is vapor of a substance that is liquid at room temperature and atmospheric pressure.