JPH0325152B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a roasting apparatus that can produce high-quality roasted coffee beans. [Prior art and its problems] Conventional coffee bean roasting devices include a direct-fire type that uses a gas burner as a heat source and coffee beans are roasted directly with the flame; However, since only the outer surface of the beans is likely to be burnt, the aroma of the coffee tends to be burnt and the mellow flavor characteristic of coffee cannot be obtained. In addition, there has been a method of roasting coffee beans using high-temperature hot air, but although the hot-air method can give coffee beans a more even temperature than the direct-fire method, it requires a large amount of hot air and a relatively long time. Coupled with the time required, the change in the composition of the coffee beans due to heating is not optimal, and it has the disadvantage that only a flavorful product can be obtained, which tends to occur in mass production. On the other hand, a coffee bean roaster is disclosed in Japanese Utility Model Publication No. 54-39518, in which coffee beans are placed in a basket-shaped rotating drum and rotated, and a gas burner is installed below the drum to roast the rotating drum. It is known that even if the coffee beans are stirred by rotation like this coffee bean roaster, direct heating like this one still tends to burn only the outer surface of the beans, resulting in a burnt smell. There is a problem in that it is difficult to obtain a smooth, mild taste. Furthermore, Japanese Utility Model Publication No. 60-40157 discloses a coffee bean roasting machine using an electric heater (hereinafter referred to as a quartz tube heater) in which a nichrome heating wire is enclosed in a quartz glass tube as a heat source. However, quartz glass tubes hardly transmit infrared rays with wavelengths of 3 to 5 μm or more, and the infrared emissivity of the metal heating rays that are the heat source is low. As shown in Figure 2, the temperature at the center of the bean rises very slowly compared to the temperature near the surface of the bean, and according to this experiment, the temperature at the center of the bean
When set to 200℃, the temperature difference can be as much as 30℃.In short, because the heat absorption is not good, it takes time for the heat to penetrate to the center of the coffee bean, and as a result, the surface of the coffee bean is concentrated. There was a problem that the thermal decomposition was more excessive than that of the previous one, and the heating change was not uniform. [Means for Solving the Problems] The present invention solves the above problems, and allows coffee beans to be roasted evenly and evenly to the core, resulting in a mild and aromatic coffee with less unpleasant taste and burnt odor. The present invention aims to provide a coffee bean roasting device that can extract coffee. For this purpose, the coffee bean roasting apparatus of the present invention has a furnace body formed by a heat insulating wall, and a substantially cylindrical furnace with a large number of small holes bored in the peripheral wall, approximately in the center of the inside of the furnace body. By supporting the rotating drum so that it can rotate in a horizontal position, and embedding the electrothermal resistor inside a plate-shaped ceramic material, the wavelength is 3 μm, 5 to 5 μm.
It is characterized in that a plurality of infrared heaters that emit infrared rays having a specific energy intensity peak at about 8 μm are arranged on the inner wall surface of the furnace so as to surround the rotating drum. [Effect] As is well known, objects have different properties depending on their molecular structure.
It has wavelength-specific selective absorption characteristics, in that it absorbs well electromagnetic waves of certain wavelengths (infrared rays are a type of electromagnetic waves), but not so much of other wavelengths. In the case of coffee beans, high absorption rates are shown in the 3 μm, 5.7 μm, and 8.3 μm zones. On the other hand, an infrared heater in which an electric heating resistor is embedded inside a plate-shaped ceramic material has a wavelength of 3 μm and 5 μm.
Since it emits infrared rays with a specific energy intensity peak at about 8 μm, it matches the infrared absorption property of coffee beans and has good heat absorption into the coffee beans. Therefore, uniform roasting can be achieved efficiently. [Example] In the figure, 1 is a furnace body in which the front/rear, upper/lower, left/right side walls 2a, 2b, 2c, 2d, 2e, and 2f are each formed into a box shape using heat insulating materials. An opening 3 is provided approximately in the center of the front wall 2a, and an opening/closing door 5 is installed in the opening 3 through which an input gutter 4 whose tip faces into a rotating drum 6, which will be described later, is inserted. Reference numeral 6 denotes a rotating drum installed at the center of the furnace body 1 to receive coffee beans.The front end surface 6a is open and the rear end surface is closed by a contact plate 6b.The peripheral wall 6c is slightly open along the rear end surface side. It is formed to have an approximately cylindrical diameter with a small diameter. In addition, there are many small holes 7 in the peripheral wall 6c.
A plurality of sill plates 8 for stirring the coffee beans are provided in a spiral manner protruding from the inner surface of the peripheral wall 6c. Further, the opening of the front end surface 6a of the rotary drum 6 is arranged close to the opening/closing door 5, and the bearing 9 protrudes outward from the rear side wall 2b on the outside of the contact plate 6b on the rear end surface.
fix the shaft rod 10 supported by the shaft rod 1;
By interlocking the rotary drum 6 with the drive motor 12 through the transmission gear group 11, the rotary drum 6 can be rotated in a horizontal position. The rotation speed of the rotary drum 6 is preferably low speed rotation, and is usually 72 rpm. In order to efficiently absorb radiant heat from an infrared heater 18, which will be described later, the rotating drum 6 may have a ceramic enamel base material or metal oxide sintered on its outer peripheral surface, which has a high infrared absorption rate.
Furthermore, the material of the rotating drum 6 is not limited to metal; if it is an integrally molded ceramic material, it will not only have high wear resistance and a long lifespan, but will also have a high infrared absorption rate, and will also be hygienic. Therefore, the coffee beans will not be contaminated. An exhaust port 13 for removing smoke is provided on the upper wall 2c of the furnace body 1, a lighting lamp 14 for illuminating the inside of the furnace body 1 is installed above the rear wall 2b, and a rotating drum is mounted on the opening/closing door 5. A viewing window 15 is provided so that the state in which the coffee beans are roasted can be visually confirmed within the chamber 6. Reference numeral 16 designates a guide member placed on the lower surface of the opening 3 to facilitate removal of roasted coffee beans from the rotating drum 6, and reference member 17 designates a guide member placed on the bottom surface of the opening 3 to facilitate removal of the roasted coffee beans from the rotary drum 6. This is a tray placed on the lower wall 2d so as to be able to be taken in and out. 18, 18... are plate-shaped infrared heaters fixedly arranged on the left and right side wall surfaces 2e, 2f so as to surround the rotary drum 6 in the same plane at appropriate distances from the rotary drum 6, and whose radiation Side 1
All eight units 9 are facing toward the rotating drum 6. The infrared heaters 18, 18... are those disclosed in Japanese Utility Model Publication No. 50-3303, which are made of ceramic material such as a ceramic board (for example, cordierite porcelain) coated with an electrothermal resistor such as nichrome wire. , zircon porcelain, alumina porcelain, etc.), the glazed ceramic plate is heated by the heat generated by the nichrome wire, so the infrared heater is not exposed to moisture. It is strong, clean, and hygienic, and has a large heat capacity that makes it difficult to cool down, so the temperature drop rate of the heater itself is slow, and the fluctuation range of the set temperature is small, so it has the advantage of uniform heating. In addition,
The ceramic plate may be curved or flat. In addition, among the eight infrared heaters placed in the furnace body 1, the two at the top are 100V100W, and the six at the bottom are
A high watt density of 100V and 200W prevents the temperature near the lower wall 2d of the furnace body 1 from becoming low. As a measure to prevent the lower temperature of the furnace body from decreasing, in addition to increasing the wattage density as described above, the lower heater mounting pitch may be made denser. Note that when the rotating drum 6 becomes longer and a plurality of infrared heaters 18 are arranged along the length of the drum, since the opening/closing door 5 is provided with the viewing window 15, heat dissipation from the opening/closing door 5 is increased. As a result, the temperature of the atmosphere inside the furnace near the opening/closing door decreases. To deal with this, by setting the watt density of the heater 18 near the opening/closing door 5 higher than the watt density of the other heaters 18, it is possible to prevent the temperature in the vicinity of the opening/closing door 5 from decreasing and to uniformly heat the area. In the coffee bean roasting apparatus having the above configuration, after heating the inside of the furnace body 1 to a predetermined temperature by passing a current through the infrared heaters 18, 18, . An appropriate amount of green coffee beans is put into a rotating drum 6, and the green coffee beans are roasted for an appropriate amount of time.
After roasting is finished, the infrared heaters 18, 18...
The power is turned off, and the opening/closing door 5 is opened while rotating the rotary drum 6 to take out the coffee beans. During roasting, the rotating drum 6 slowly rotates at 72 rpm, and the coffee beans inside the rotating drum 6 are stirred by the chopping board 8, so the coffee beans inside the rotating drum 6 receive radiation from the infrared heaters 18, 18... In addition to direct heating by absorbing infrared rays, conductive heat due to contact with the inner surface of the rotating drum 6,
The boundary heat film on the surface of the coffee beans is removed by the convection of hot air that accompanies the stirring, and the coffee beans are heated by evenly receiving the convection heat. FIG. 3 shows the infrared absorption spectrum curve of coffee beans, and FIG. 4 shows the emissivity spectral distribution curve of the infrared heater used here, measured by the differential infrared emissivity measurement method. As can be seen from Figure 3, coffee beans exhibit a high infrared absorption rate of 50% or more at most wavelengths, but especially at wavelengths of 3 μm, 5.7 μm,
It can be seen that the infrared absorption rate peaks at three points at 8.3 μm. On the other hand, it can be seen that the specific energy intensity of the infrared rays emitted from the infrared heaters 18, 18, . From these facts, it can be seen that the infrared rays emitted from the infrared heaters 18, 18, . . . are absorbed by the coffee beans with a very high absorption rate. Infrared rays of this wavelength are well absorbed into the interior of the coffee bean, and as shown in Figure 6, which compares the experimental results with Figure 5, the temperature at the center of the bean is approximately equal to the temperature near the surface of the bean. The temperature can be raised. Table 1 shows various types of coffee beans from different production areas.
Infrared heater method according to the present invention and conventional hot air method

【table】

[Table] Shows the experimental results of roasting using the formula. The degree of roasting was city roast. As can be seen from this result, the infrared heater method according to the present invention produces "dusty,""muddy,""dirty," and "unpleasant sourness" in terms of flavor and flavor.
A smooth and well-balanced coffee with less bad taste was obtained. Next, Table 2 shows the results of an experiment comparing the quality deterioration due to storage of Brazil's No. 2 coffee beans roasted using the infrared heater method according to the present invention and the conventional hot air method.

[Table] Conditions Storage temperature 37℃ Judgment method Cuptest coffee beans are stored in a pulverized state using a kraft paper bag From these results, hot air roasted coffee beans already have an unpleasant sour taste and a dusty smell after being heated at 37℃ for one day. It's worn out, and the deterioration has progressed further since the second day. On the other hand, with infrared roasting, there is less deterioration at any roasting temperature, and there is less unpleasant acidity, astringency, and dustiness even when stored, and although it changes slightly from the second day, it is still good. Well, I was able to maintain this until the 8th day. Finally, Table 3 shows the results of an experiment comparing the palatability of canned coffee between the infrared heater method according to the present invention and the conventional hot air method.

〔Effect of the invention〕

As explained in the embodiments above, the coffee bean roasting apparatus of the present invention rotates and stirs coffee beans in a rotating drum, and detects the infrared absorption characteristics of the coffee beans by using a plurality of infrared heaters arranged around the drum. Since it emits infrared rays with a matching wavelength of 3 μm and a peak of around 5 to 8 μm,
Coffee beans can be heated evenly and efficiently to the inside, creating an unprecedented mild taste.
It has the beneficial effect of allowing aromatic coffee to be extracted.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a coffee bean roasting apparatus showing an embodiment of the present invention, FIG. 2 is a cross-sectional view thereof, and FIG. 3 is an infrared absorption spectrum diagram of coffee beans.
Fig. 4 is an emissivity spectral distribution diagram of the infrared heater, Fig. 5 is a curve diagram showing the temperature change of green coffee beans during heating using a conventional quartz tube heater as a heat source, and Fig. 6 is an infrared ray according to the present invention. It is a curve diagram showing the temperature change of green coffee beans during heating using a heater as a heat source. 1...Furnace body, 2a...Front side wall, 4...Charging gutter,
5...Opening/closing door, 6...Rotating drum, 6a...Front end surface, 7...Small hole, 8...Front board, 18...Infrared heater, 19...Radiation plate.

Claims (1)

[Claims] 1. A furnace body is formed by a heat insulating wall, and a generally cylindrical rotating drum with a large number of small holes bored in the peripheral wall is supported at approximately the center of the inside of the furnace body so as to rotate horizontally. By embedding the electrothermal resistor inside the plate-shaped ceramic material, the wavelength can be reduced to 3 μm.
A coffee bean roasting device characterized in that a plurality of infrared heaters that emit infrared rays having a specific energy intensity peak at about 5 to 8 μm are arranged on the inner wall surface of the furnace so as to surround the rotating drum.