JP2017042079A - Coffee taste adjustment method and device thereof and roasted coffee beans produced by the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coffee taste adjustment device capable of adjusting bitterness of coffee beans for achieving a gentle coffee taste which is unique to coffee, when bitterness is too high in coffee extracted from roasted coffee beans, without limitation to a coffee kind such as coffee beans of arabica variety and robusta variety.SOLUTION: The invention is configured to put roasted coffee beans 13 which were roasted by heating from surfaces of coffee beans, by a heat source such as hot wind, near infrared radiation, far infrared radiation or direct fire, into a rotary drum 18 in an applicator 11 for radiation a wave of a microwave, then stir the roasted coffee beans 13 in the rotary drum 18 while performing dielectric heating by radiation of microwave, for reducing bitterness in extracted coffee and achieving a gentle coffee taste.SELECTED DRAWING: Figure 2

Description

  The present invention relates to the bitterness of coffee extracted from roasted coffee beans by further heating the roasted coffee beans with a heat source such as hot air, mid-infrared rays, far-infrared rays, or direct fire by dielectric heating. The present invention relates to a method and apparatus for adjusting the coffee taste to reduce the amount of coffee.

Coffee can be broadly divided into two types: Arabica and Robusta.
About 60% of the coffee beans produced are Arabica and their origin is Ethiopia.
This Arabica coffee bean is suitable for cultivation in tropical highlands at an altitude of 1000m to 2000m, but because of its high altitude, it is very troublesome to grow, and it is also vulnerable to frost, dryness, pests, etc. Therefore, since it is a variety which is difficult to grow, it is expensive.
Incidentally, coffee extracted from this type of coffee beans is said to have a strong acidity and a sweet scent like flowers.

On the other hand, Robusta occupies over 30% of coffee beans, but it is resistant to disease, can be cultivated in low altitudes of 300m to 800m above sea level, and is easy to grow, so it becomes cheap coffee beans Yes.
The reason why the production volume is small despite the fact that it is an inexpensive coffee bean is due to its unique strong bitterness.

  Therefore, in fact, high-grade coffee is extracted from roasted coffee beans made by roasting Arabic coffee beans, and even cheap coffee roasted coffee mixed with Arabic coffee beans and Robusta coffee beans Many are extracted from beans.

Since the coffee extracted from Robusta coffee roasted beans is too bitter, the coffee is extracted in the form of roasted beans.
That is, if the roasted coffee beans are crushed and the components are sufficiently extracted, the bitterness will be too strong.
From the above situation, Arabica coffee beans are expensive but have a production share of 60%.

As is well known, coffee beans are roasted by an external heating type roasting machine that performs heat treatment using a heat source such as hot air, mid-infrared rays, far-infrared rays, or direct fire.
In an external heating type roasting machine, heat energy obtained on the surface of the coffee beans is diffused toward the center of the coffee beans by heat conduction.

As a result, since the temperature is high when the surface of the coffee beans is roasted and the temperature is lower in the center than the surface, the aroma is good and the taste is mellow and balanced.
However, even if the coffee beans of the same Arabica type are added, factors such as the production area and the climate are added, so the coffee that is roasted in the same way, but the extracted coffee has a slightly stronger bitterness is there.

Robusta coffee beans are also roasted by a similar external heating roasting machine.
However, coffee extracted from Robusta roasted coffee beans is treated as cheap coffee because it has a very strong bitterness even though it has aroma and taste peculiar to coffee.

On the other hand, a microwave roasting apparatus for roasting coffee beans by microwave heating has been proposed.
The microwave roasting apparatus includes a container formed of a microwave transmitting material, a drive unit that rotates the container, and further sets the container and the drive unit on a table in a microwave oven. It is as.
This microwave roasting apparatus puts coffee beans into a container, irradiates microwaves from the outside of the container, and rotates the container by the driving unit and the container by the table of the microwave oven. And roast the coffee beans by microwave heating.

JP 2005-137303 A

As mentioned above, if Arabica coffee beans are roasted by an external heating type roasting machine, the heat energy obtained on the surface of the coffee beans is transferred and diffused toward the center of the beans, resulting in the surface of the coffee beans Since the temperature is high in the roasted state and the temperature in the center is lower than the surface, it is possible to extract mellow coffee with a good aroma and a balanced taste.

However, as already mentioned, even Arabica coffee beans are subject to variable factors such as production area and climate, so the coffee that has been roasted in the same way is not a bitter to the extracted coffee. There is something a little stronger.
Robusta coffee roasted beans roasted in the same manner by an external heating type roasting machine have a very strong bitterness even if the extracted coffee has a characteristic scent and taste.

Furthermore, the microwave roasting device infiltrates microwaves from all directions of the coffee bean surface, so the power density inside is higher than the surface, the surface is cooled by touching the outside air, etc. Less than the internal roast.
For this reason, the coffee extracted from roasted coffee beans roasted by microwave heating becomes a coffee with a strong sour taste with less bitterness, and therefore, roasted coffee beans that are less preferred as a coffee taste can be produced.

Therefore, in the present invention, when there is a lot of bitterness of coffee extracted from roasted coffee beans, not just Arabica coffee beans or Robusta coffee beans, in consideration of the above-mentioned circumstances, the bitterness is adjusted by reducing the bitterness. -It aims at proposing the adjustment method and apparatus of the coffee taste which can be made into the mellow coffee taste peculiar to He.

In order to achieve the above-described object, in the present invention, as a first invention, roasted coffee beans heated and roasted from the surface of the coffee beans with a heat source such as hot air, mid-infrared rays, far-infrared rays or direct fire, We propose a coffee taste adjustment method that reduces the bitterness of coffee extracted from roasted coffee beans to a mellow taste by subjecting it to dielectric heating by exposure to radio waves from the high frequency band to the microwave band.

  As a second invention, in a roasting apparatus for storing coffee beans in a roasting container equipped with a heat source such as hot air, mid-infrared rays, far-infrared rays or direct fire, and heating and roasting from the surface of the coffee beans, The roasted coffee beans roasted by the roasting device are stored in an applicator that radiates radio waves from the high frequency band to the microwave band and heated by dielectric heating to reduce the bitterness of the extracted coffee. We propose a coffee flavor adjustment device that can be used.

  As 3rd invention, the coffee roasted beans produced in the coffee taste adjustment apparatus of 2nd invention mentioned above are proposed.

Coffee beans (raw beans) are heated and roasted from the surface by a heat source such as hot air or direct fire, but the extracted coffee may have a bitterness although it has a smell and taste peculiar to coffee.
This may occur not only in Robusta coffee beans but also in roasted beans of Arabica coffee beans.
In other words, roasted coffee beans are rich in chlorogenic acid, which is a causative substance of bitterness.

The present invention is characterized in that chlorogenic acid, which is a cause of bitterness, is reduced by additionally heat-treating such roasted coffee beans by irradiating radio waves from a high frequency band to a microwave band. It has become.
In other words, when radio waves in the microwave band are irradiated from the high frequency band, the radio waves penetrate into the roasted coffee beans, and the organic polymer and moisture constituting the roasted coffee beans absorb the radio waves and generate heat.

For this reason, when microwave waves are irradiated from the high frequency band, the surface of the coffee beans is cooled at the ambient temperature, but the inside is not cooled, so the interior of the roasted coffee beans becomes hot.
As a result, the temperature rise level of the roasted portion near the surface of the roasted coffee beans is low, so the aroma and taste peculiar to coffee remains unchanged, and chlorogenic acid is the causative agent of the bitterness present in the roasted coffee beans The roasted coffee beans are able to enhance the mellow coffee taste while maintaining the coffee-specific aroma and taste.

Furthermore, according to the present invention, since the residual level of chlorogenic acid in roasted coffee beans can be optimized, roasted coffee beans can be pulverized to sufficiently extract coffee components.
Therefore, roasting Robusta coffee beans, which have a very strong bitterness, can dramatically increase the amount of extraction, so that coffee can be provided at low cost, and moreover, less coffee beans are extracted from the coffee components. be able to.

In roasted coffee beans, a large amount of chlorogenic acid remains in the interior, particularly near the center, according to the internal temperature distribution. And the decomposition of chlorogenic acid is related to the temperature, and the lower the temperature, the less the decomposition proceeds.
Therefore, as described above, roasted coffee beans that are strongly bitter in the extraction component can be irradiated with microwave waves from the high frequency band to selectively reduce the chlorogenic acid that causes bitterness. .

It is a graph which shows the amount of coffee components of roasted coffee beans roasted with hot air, mid-infrared and far-infrared heat sources. It is a simplified block diagram of the additional heat processing apparatus which shows the additional heating apparatus used as embodiment of this invention, and irradiates a coffee roast bean with a microwave. It is a block diagram which is one Embodiment of this invention which showed the implementation process which additionally heat-processes the coffee roasted bean which roasted Robusta-type coffee bean with hot air with a microwave. A comparison of the amount of coffee components of roasted coffee beans, which were robusta coffee beans heat-treated by the practice of the present invention, and the amount of coffee components of roasted coffee beans roasted using Robusta coffee beans as a hot air heat source It is a graph. It is the block diagram which is other embodiment of this invention which showed the implementation process which additionally heat-processes the coffee roasted bean which roasted the coffee beans of Robusta seed | species with each heat source of a hot wind, a mid-infrared ray, and a far-infrared ray by microwave is there. Block diagram showing another embodiment in which Robusta coffee beans are roasted with hot air, mid-infrared and far-infrared heat sources, and coffee roasted beans are additionally heated with microwaves. It is.

Next, embodiments of the present invention will be described with reference to the drawings.
First, roasting experiments of Robusta coffee beans (raw beans) were performed using conventional roasting machines such as A, B, and C described below.
In this experiment, the surface temperature of the coffee beans was set to 240 ° C. and roasted, and the extracted components were analyzed by a conventional roasting method.
The water content of coffee beans (raw beans) is approximately 10%, but the completion of roasting is generally the time when the moisture content of coffee beans, which is the optimum roasting condition, becomes 2%.

A. Experiments using hot air as a heat source 200g of Robusta coffee beans (raw beans) at room temperature was roasted for 18 minutes using hot air at 240 ° C in a home roasting machine, and a dry state with a moisture content of about 2% was confirmed. Finish roasting. Then cooled at room temperature.

B. Experiments using mid-infrared rays as a heat source Place 200 g of Robusta coffee beans (raw beans) at room temperature in a bowl, stir, roast for 12 minutes using a mid-infrared heater with a heater surface temperature of 1050 ° C, moisture content of about 2% After confirming the dry condition, finish roasting and cool with air at room temperature.

C. Experiment using far-infrared rays as a heat source 200 g of Robusta coffee beans (raw beans) at room temperature are put in a bowl, stirred, roasted for 14 minutes using a far-infrared heater with a heater surface temperature of 800 ° C, and dried with a moisture content of about 2% Check the condition and finish roasting. Cool with room temperature air.

FIG. 1 is a graph showing the amount of coffee components obtained by analyzing the components of coffee extracted from the roasted coffee beans roasted in Experiments A, B, and C described above.
Paying attention to the amount of chlorogenic acid in this graph, it is estimated that roasting of coffee beans at the time when the moisture content reached approximately 2% was the most advanced in hot air roasting.
Further, as can be seen from FIG. 1, the level of chlorogenic acid indicates that bitterness is very strong in any roasting.
In order to increase the mildness of the coffee taste, the chlorogenic acid is preferably at a level of 1 (g / 100 g) or less.

FIG. 2 is a simplified configuration diagram of an additional heat treatment apparatus used as an embodiment of the present invention.
As shown in the figure, the additional heat treatment apparatus 10 includes an applicator 11 formed of a microwave reflector such as a non-magnetic stainless material, and a door 12 made of the microwave reflector is provided in the opening of the applicator 11. It is provided so that it can be opened.
The door 12 is opened to store the roasted coffee beans 13 in the applicator 11.
The door 12 is normally closed, but a microwave leakage prevention structure is provided in the gap between the door 12 and the applicator 11.

A microwave generator 14 is connected to the applicator 11 via a waveguide, and a hot air supply device 15 is connected to the applicator 11 via a duct.
In addition, the grating | lattice 16 which consists of a microwave reflector is provided in the connection port of the hot air supply machine 15, and it is set as the structure which lets a hot air pass through the applicator 11 and interrupts the microwave transmitted to the hot air supply machine 15 side.

A rotating drum 18 rotated by a motor 17 is provided in the applicator 11, and a stirring blade 19 is provided in the rotating drum 18 so as to stir the roasted coffee beans 13 put in the rotating drum 18. It is.
The rotating shaft 20 connected to the rotating drum 18 holds the rotating drum 18 at an angle, and is provided with a bearing having a microwave leakage prevention structure and is inserted into the applicator 11.

Next, the present embodiment will be described with reference to the block diagram of FIG.
First, 200 grams of Robusta coffee beans (raw beans) were roasted for 15 minutes using hot air at 240 ° C. in a home roasting machine, and the roasting was completed after confirming that the moisture content was about 2%. Then, it was cooled at room temperature. (See steps ST31, ST32, ST33 in FIG. 3)

When the surface temperature of the roasted coffee beans was approximately 40 ° C. after cooling at room temperature, the roasted coffee beans were microwave heated by the additional heat treatment apparatus 10 for 4 minutes.
That is, the roasted coffee roasted beans 13 are put into the rotating drum 18 in the applicator 11 and irradiated with 200 W of microwaves while being stirred by the stirring blades 19, heated for 4 minutes, and then heated at room temperature. It was cooled with. (See steps ST34 and ST35 in FIG. 3)

During the microwave heating, hot air at 100 ° C. was supplied from the hot air supply machine 15 into the applicator 11.
The supply of hot air by the hot air supply machine 15 is performed for the purpose of saving the microwave power, and since the hot air is supplied for about 4 minutes, the coffee taste is not affected.
Therefore, the hot-air supply machine 15 does not necessarily have to be provided if saving of microwave power is not taken into consideration.

FIG. 4 is a graph showing the amount of coffee components extracted from roasted coffee beans microwave-heated as described above.
In this graph, the component amount of the hot air roasting shown in FIG. 1 is also shown.
As can be seen from this graph, the roasted coffee beans produced in this embodiment have chlorogenic acid halved and quinic acid doubled.

As a result, chlorogenic acid, which is a cause of bitterness, is reduced, so that even Robusta coffee roasted beans with very strong bitterness have a mellow taste.
Therefore, even Robusta coffee roasted beans can be used as a pulverized product, so that the coffee components can be sufficiently extracted.

  FIG. 5 is a block diagram similar to FIG. 3 shown as another embodiment, and Robusta coffee beans (raw beans) are roasted by an external heating type roasting machine using hot air, mid-infrared rays, and far infrared rays as heat sources. After that, the roasted coffee beans are microwaved in the same manner as described above to reduce chlorogenic acid.

  FIG. 6 is a block diagram showing still another embodiment. In this embodiment, Robusta coffee beans are roasted by an external heating type roasting machine and then continuously microwave-heated without cooling. The other features are the same as the above-described embodiment.

  Although the embodiments of the present invention have been described above, hot air heating, infrared heating, and microwave heating will now be described in some detail.

(1) Hot air heating Hot air heating does not raise the temperature of coffee beans above the temperature of hot air, no matter how long the coffee beans are exposed to hot air.
The inside of the coffee beans always shows the hot air temperature or less.

(2) Infrared heating In infrared heating, when coffee beans are exposed to infrared rays for a long time, the surface temperature of the coffee beans easily exceeds the upper limit temperature of roasting.
In order to control the surface temperature and moisture content, it is necessary to optimize the intensity of infrared rays and the irradiation time.
In addition, since the wavelength from near infrared rays to far infrared rays is roughly 1 μm to 100 μm, infrared rays are almost heated on the surface.

(3) Dielectric heating (high frequency heating / microwave heating)
Since the penetration depth of electric waves in dielectric heating (power half-earthquake intensity) is inversely proportional to the frequency, the penetration depth of radio waves in the high frequency band is deeper than that in the microwave band.
For example, in the case of water, the half-power depth of the microwave at 2.45 GHz is about 10 mm.
Since coffee beans (raw beans) are 10 mm or less, 2.45 GHz microwaves can penetrate the coffee beans.

Then, the microwave that has entered the roasted coffee beans generates heat due to absorption of the microwave power by the organic polymer or water containing polar groups and ions constituting the roasted coffee beans.
In the case of roasted coffee beans, microwaves penetrate from all directions on the surface, so the internal power density is higher than the surface and the surface that comes into contact with the outside air is cooled, so the internal temperature is higher than the surface. .
From this, it can be seen that the microwave is effective for reducing chlorogenic acid in roasted coffee beans.

  Although the preferred embodiments have been described above, the present invention is not limited to Robusta coffee beans that are very strong in bitterness, and is similarly applied to Arabica coffee beans that are in bitterness, so that mellow coffee that relieves bitterness is used. Can be provided.

  The present invention is applied as an apparatus for adjusting coffee taste, which can be a roasted coffee bean that can soften the bitterness of coffee and extract mellow coffee.

DESCRIPTION OF SYMBOLS 10 Additional heat processing apparatus 11 Applicator 12 Door 13 Coffee roasted beans 14 Microwave generator 15 Hot-air supply machine 16 Lattice 17 Motor 18 Rotating drum 19 Stirring blade 20 Rotating shaft

Claims (3)

  By heating the roasted coffee beans from the surface of the coffee beans with a heat source such as hot air, mid-infrared rays, far-infrared rays, or direct fire, by subjecting them to dielectric heating by exposing them to microwave waves from the high frequency band, A method for adjusting the coffee taste, which can reduce the bitterness of coffee extracted from roasted coffee beans to create a mellow taste.   In a roasting apparatus in which coffee beans are stored in a roasting container equipped with a heat source such as hot air, mid-infrared ray, far-infrared ray, or direct fire and heated from the surface of the coffee beans, roasting is performed by the roasting device. The coffee roasted beans are stored in an applicator that radiates radio waves from the high frequency band to the microwave band, and dielectrically heated to reduce the bitterness of the coffee extracted from the roasted coffee beans, resulting in a mellow taste. Coffee flavor adjuster. Roasted coffee beans produced in the coffee flavor adjusting device according to claim 2.

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