How to roast coffee beans

Abstract

To provide a charcoal roasting method for coffee beans, which can produce roasted coffee beans having a good flavor and aroma while using low-temperature roasting to prevent damage to trigonelline contained in the green coffee beans. [Solution] The charcoal roasting method for coffee beans according to the present invention includes a loading step in which 15-25 kg of green coffee beans are loaded into a charcoal roaster (4) at loading timing a, when the temperature inside the oven of a charcoal roaster (1) being heated by burning charcoal is higher than a bottom temperature range that includes the bottom temperature, and a termination step in which the roasting of the coffee beans by burning charcoal is terminated at termination timing c, when the temperature inside the oven has risen after dropping to the bottom temperature due to the loading of the green coffee beans, and is within the termination temperature range. The rise time range from bottom timing b, when the temperature has dropped to the bottom temperature, to termination timing c is 600-700 seconds, the bottom temperature range is 95-110°C, and the termination temperature range is 185-195°C.

Description

[Technical Field]

[0001] The present invention relates to a charcoal roasting method for coffee beans that is capable of producing roasted coffee beans with a good aroma and flavor, while using low-temperature roasting to prevent damage to trigonelline contained in green coffee beans. [Background technology]

[0002] Green coffee beans contain the nutritional component "trigonelline," which has recently been attracting attention for its effects on activating the brain nerves, increasing concentration, and preventing dementia.

[0003] However, the nutritional component trigonelline contained in raw coffee beans is reduced by heating during roasting, and it is known that thermal decomposition occurs rapidly at temperatures around 200°C.

[0004] To solve this problem, a method for producing roasted coffee beans that suppresses the decomposition of trigonelline has been disclosed, characterized by a roasting temperature in a roaster of 100 to 250°C and an accumulated roasting temperature of 3250°C or less. In Table 1, in the case of charcoal roasting, roasting is completed at a maximum temperature of 170°C (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-124527 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if roasting is stopped when the temperature inside the oven rises to about 170°C, as in the above patent documents, roasting will end at an early stage when the aroma and flavor components of the coffee beans begin to be produced through chemical changes caused by heating (so-called extra-light roasting), and the coffee extracted from these extra-lightly roasted coffee beans will have a very weak aroma and flavor specific to coffee, and will not have a deep flavor or richness.

[0007] Therefore, an object of the present invention is to provide a charcoal roasting method for coffee beans that can produce roasted coffee beans with a good aroma and flavor, while using low-temperature roasting to prevent damage to the trigonelline contained in the green coffee beans. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a coffee bean roasting method comprising: a loading step of loading 15-25 kg of green coffee beans into a charcoal roaster at a loading timing when the temperature inside the oven of the charcoal roaster being heated by burning charcoal is higher than a bottom temperature range that includes the bottom temperature; and an end step of ending the roasting of the coffee beans by burning charcoal at an end timing when the temperature inside the oven, to which it has risen after having dropped to the bottom temperature due to the loading of the green coffee beans, is within an end temperature range, wherein the rise time range from the bottom time when the temperature has dropped to the bottom temperature to the end timing is 600-700 seconds, the bottom temperature range is 95-110°C, and the end temperature range is 185-195°C.

[0009] This configuration makes it possible to produce roasted coffee beans with a good aroma and flavor while preventing the loss of trigonelline contained in the green coffee beans. It also makes it possible to significantly shorten the roasting time.

[0010] The method further includes a finishing step of reducing the rate of increase of the kiln temperature within a range in which the kiln temperature does not decrease when the kiln temperature rises from the bottom temperature to a finishing temperature range that is lower than the end temperature range, and the finishing temperature range is preferably 165-185°C.

[0011] This configuration allows the aroma and flavor of the coffee beans to be further developed. [Effects of the Invention]

[0012] According to the charcoal roasting method for coffee beans of the present invention, it is possible to produce roasted coffee beans with a good aroma and flavor, even while using low-temperature roasting to prevent damage to the trigonelline contained in the green coffee beans. [Brief explanation of the drawings]

[0013] [Figure 1] An explanatory diagram of the structure of the charcoal roaster used in the present invention. [Figure 2] 1 is an explanatory diagram of the change in temperature inside the oven when roasting coffee beans according to the present invention. [Figure 3] FIG. 1 shows the results of a sensory test of coffee extracted from coffee beans produced using the coffee bean roasting method according to the present invention. [Figure 4] FIG. 1 shows the results of a sensory test conducted to confirm the effectiveness of the rise time range according to the present invention. [Figure 5] FIG. 10 shows the results of a sensory test conducted to confirm the effectiveness of the bottom temperature range according to the present invention. [Figure 6] FIG. 1 shows the results of a sensory test conducted to confirm the effectiveness of the finishing temperature range according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

[0015] The coffee bean roasting method of the present invention uses a charcoal roaster, so first, an example of the structure of a charcoal roaster will be described using Figure 1.

[0016] As shown in FIG. 1, the charcoal roaster 1 includes a furnace 2, a charcoal inlet 3, a kiln 4, a bean inlet 5, a bean outlet 6, and an exhaust outlet 7.

[0017] Charcoal is fed into the furnace 2 through a charcoal feed port 3.

[0018] Oven 4 is located above furnace 2, and green coffee beans placed into oven 4 through bean inlet 5 are heated by the combustion of charcoal placed in furnace 2 and roasted.

[0019] It is common to keep the charcoal inlet 3 closed during roasting. In other words, as a rule, no charcoal is added or removed during roasting, and roasting is carried out by continuous combustion of the charcoal that was initially added.

[0020] After roasting is completed, the bean discharge port 6 is opened and the roasted coffee beans are discharged from the oven 4. Naturally, the bean discharge port 6 is also closed during roasting.

[0021] The exhaust port 7 is used to exhaust air from the kiln 4, and the temperature inside the kiln 4 can be adjusted by adjusting the amount of exhaust.

[0022] Next, referring to FIG. 2, a description will be given of the change in temperature inside the oven 4 when roasting coffee beans using the charcoal roaster 1.

[0023] First, before the green coffee beans are added, the temperature inside the oven is raised by burning charcoal that has been placed in oven 2.

[0024] Then, when the green coffee beans are loaded into the oven 4 (loading timing a), the temperature inside the oven drops (section A), drops to the bottom temperature (bottom timing b), and then rises again (section B). In section B, the green coffee beans are drained, and then the Maillard reaction occurs. If the draining is insufficient, the coffee extracted from the roasted coffee beans will have a bitter taste. On the other hand, if the draining is excessive, the aroma and flavor will disappear.

[0025] Then, when the temperature inside the oven has risen to the desired temperature, the worker removes the roasted coffee beans from the oven 4 (end timing c).

[0026] In the present invention, in order to prevent damage to the trigonelline contained in the green coffee beans, the roasted coffee beans are removed from the oven 4 while the temperature inside the oven is within the end temperature range (185-195°C) (low-temperature roasting).

[0027] The roasted coffee beans removed from the oven 4 are cooled in a short time (about a few minutes) to at least remove the heat, since it is necessary to stop the roasting process.

[0028] In this way, it is possible to produce roasted coffee beans that retain a large amount of trigonelline. However, with conventional charcoal roasting, the beans are roasted over a long period of time at a low heat (because section B in Figure 2 is long), which means that the coffee beans are exposed to heat for a long period of time, resulting in the loss of aroma and flavor of the coffee beans and the lack of a deep, rich flavor.

[0029] On the other hand, if roasting is done over high heat to shorten the heating time, the end temperature range (185-195°C) will be reached quickly, resulting in insufficient dehydration of the green coffee beans.

[0030] Therefore, after much experimentation, the inventors of the present application discovered a method for producing roasted coffee beans that have a deep flavor and richness, even when roasted at a low temperature using charcoal and with the water properly removed. Below, we will explain the process of discovering this method, based on the results of experiments conducted on roasting 15-25 kg of green coffee beans.

[0031] First, we discovered that if section B was longer than 700 seconds, the aroma of the coffee beans would disappear, and if it was shorter than 600 seconds, insufficient draining caused a noticeable bitter taste, so we discovered that section B needed to be included in the rise time range (600-700 seconds).

[0032] As a result of the above, Section B is fixed at 600-700 seconds. In this case, if Section B starts from a low bottom temperature, roasting will be carried out at a high temperature rise rate, and if Section B starts from a high bottom temperature, roasting will be carried out at a low temperature rise rate.

[0033] However, when the bottom temperature was lower than 95°C, the coffee tasted dull and had little aroma. This is thought to be because section B started at a low temperature, which caused excessive heat to enter the coffee beans, resulting in excessive dehydration.

[0034] On the other hand, when the bottom temperature was higher than 110°C, the surface of the coffee beans became overly burnt and the beans had a pronounced bitter taste. In order for adequate dehydration to occur, heat needs to be properly transferred to the inside of the coffee beans, which requires a period of roasting at a temperature that is not too high. However, when the bottom temperature was higher than 110°C, section B started from a high temperature, which prevented heat from being properly transferred to the inside of the coffee beans, resulting in insufficient dehydration.

[0035] From the above, it was found that in order to produce roasted coffee beans with good flavor and a high level of remaining trigonelline, the bottom temperature must be within the bottom temperature range (95-110°C) and the temperature inside the kiln must reach the end temperature range (185-195°C) within the rise time range (600-700 seconds).

[0036] By adjusting the type and amount of charcoal added and the exhaust port 7, it is possible to "kiln the bottom temperature within the bottom temperature range (95-110°C) and the temperature inside the kiln to reach the end temperature range (185-195°C) within the rise time range (600-700 seconds)."

[0037] In order for the bottom temperature to be within the bottom temperature range (95-110°C), the temperature inside the oven at timing a when the green coffee beans are added must be at least 10°C higher than the bottom temperature range (95-110°C).

[0038] Furthermore, the inventors of the present application discovered that when the temperature rises from the bottom temperature to the finishing temperature range (165-185°C), which is lower than the end temperature range (185-195°C) (finishing timing d in Figure 2), by performing a finishing process in which the rate of increase in the oven temperature is reduced within a range in which the oven temperature does not drop, the aroma and flavor of the coffee beans are further developed. This is thought to be because the chemical reactions inside the coffee beans are promoted by slowing down the heating of the coffee beans at the end of roasting.

[0039] In order to reduce the rate of increase in the temperature inside the kiln, it is conceivable to increase the amount of exhaust from the exhaust port 7, for example.

[0040] In the above experiment, as long as the green coffee beans added were suitable for medium roasting, there was no significant difference in the aroma and flavor of the roasted coffee beans produced by the above method.

[0041] Furthermore, as long as the amount of coffee beans added was in the range of 15-25 kg, there was no significant difference in the aroma and flavor of the roasted coffee beans produced by the above method.

[0042] As described above, by using the coffee bean roasting method of the present invention, roasted coffee beans with a good aroma and flavor can be produced, even when low-temperature roasting is used to prevent damage to the trigonelline contained in the green coffee beans.

[0043] The present invention will be described in detail below based on examples. Example 1 The temperature inside a charcoal roaster (FUJI ROYAL COFEE ROASTER TYPE R-130 charcoal 30 kg roaster (Fuji Coffee Machine Co., Ltd.)) was raised by burning binchotan charcoal. 20 kg of "Brazil Amarelo Bourbon" green coffee beans were added to the oven when the oven temperature reached 118°C. One minute and 27 seconds after addition, the oven temperature reached the bottom temperature (99°C) and began to rise again. When the oven temperature subsequently reached 180°C, the oven was vented to slow the rate of increase in the oven temperature. The roasted coffee beans were removed from the oven when the oven temperature reached 189°C. The removed coffee beans were cooled for several minutes on a cooling device attached to the charcoal roaster. The time required from reaching the bottom temperature to removing the roasted coffee beans was 10 minutes and 26 seconds (626 seconds). The time it took from adding the green coffee beans to removing them was 11 minutes and 53 seconds.

[0044] The roasted coffee beans produced in this manner were analyzed for trigonelline content at the Japan Food Analysis Center, and found to contain four times more trigonelline than the applicant's existing product, "Brazil Bourbon Coffee Furi Furi Bag," which is also made from "Brazil Amarelo Bourbon" green coffee beans, but is not low-temperature roasted. In other words, the roasted coffee beans produced according to the present invention contained four times more trigonelline than those roasted at a normal temperature (roasted at a higher temperature than low).

[0045] In addition, five panelists conducted a sensory evaluation of the aroma and flavor of the coffee extracted from the roasted coffee beans produced using the above process on a five-point scale (5: very good, 4: good, 3: average, 2: not so good, 1: bad). As shown in Figure 3, all five panelists gave it a high rating of "5," with comments such as "a sweet taste reminiscent of nutty flavor and brown sugar, wrapped in a soft, rich flavor and a mellow, rich aroma."

[0046] Figures 4 to 6 show the results (average values ​​of five people) of sensory evaluation of flavor on a 5-point scale (5: very good, 4: good, 3: average, 2: not so good, 1: bad) when the values ​​of the "rising time range," "bottom temperature range," and "finishing temperature range" discovered above were changed to confirm their effectiveness. The sensory evaluation was conducted under almost the same conditions as those listed in the above examples, except for the items that were changed.

[0047] Figure 4 shows the sensory test results when roasting was performed with different "rising time ranges," and a rating of "4" or higher was obtained in the "600-700 seconds" range.

[0048] Figure 5 shows the sensory test results when roasting coffee beans at different "bottom temperature ranges," and a rating of "4" or higher was obtained in the "95-110°C" range.

[0049] Figure 6 shows the results of a sensory test in which roasting was performed with different "finishing temperature ranges." All five panelists gave the coffee a rating of "5" in the "165-185°C" range.

[0050] As explained above, the present invention makes it possible to produce roasted coffee beans with good flavor and aroma while suppressing the loss of trigonelline contained in green coffee beans.

[0051] Furthermore, when coffee beans (medium roast) are normally produced by low-temperature roasting over charcoal, as shown in Table 1 of Patent Document 1, it takes nearly 30 minutes until the beans are completely roasted. However, with the present invention, the process from adding the green coffee beans to roasting them through charcoal combustion can be completed in less than 12 minutes (11 minutes and 53 seconds in the above example), significantly shortening the roasting time. 1 charcoal roaster 2 furnace 3 Charcoal inlet 4 kiln 5 Bean inlet 6 Bean outlet 7. Exhaust port Section A Section B a. Timing of input b Bottom timing c End timing d Finishing timing

Claims

[Claim 1] a step of charging 15-25 kg of green coffee beans into the oven at a timing when the temperature inside the charcoal roaster being heated by burning charcoal is higher than a bottom temperature range that includes the bottom temperature; a termination step of terminating the roasting of the coffee beans by burning the charcoal at a termination timing when the temperature inside the oven, which has risen after having dropped to the bottom temperature due to the addition of the green coffee beans, is within a termination temperature range; a finishing step of reducing the rate of increase of the kiln temperature within a range in which the kiln temperature does not decrease when the kiln temperature rises from the bottom temperature to a finishing temperature range that is lower than the final temperature range; Equipped with The temperature inside the kiln does not exceed the end temperature range from the bottom timing at which the temperature has dropped to the bottom temperature until the end timing, The rise time range from the bottom timing at which the temperature drops to the bottom temperature to the end timing is 600-700 seconds. The bottom temperature range is 95-110°C, The end temperature range is 185-195°C, The finishing temperature range is 165-185°C, A method for roasting coffee beans, characterized by:

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