Coffee bean roasting methods

Abstract

This invention provides a charcoal roasting method for coffee beans that allows for the production of roasted coffee beans with good aroma and flavor while using low-temperature roasting to suppress the loss of trigonelline contained in green coffee beans. [Solution] In the charcoal roasting method for coffee beans according to the present invention, an input step is performed in which 15-25 kg of green coffee beans are put into the kiln 4 at input timing a, when the temperature inside the kiln of the charcoal roaster 1, which is being heated by the combustion of charcoal, is higher than the bottom temperature range which includes the bottom temperature. An end step is performed in which the roasting of the coffee beans by charcoal combustion is ended at end timing c, when the temperature inside the kiln, which has risen after dropping to the bottom temperature due to the input of the green coffee beans, is included in the end temperature range. The rise time range from bottom timing b, when the temperature has dropped to the bottom temperature, to end timing c is 600-700 seconds, the bottom temperature range is 95-110°C, and the end temperature range is 185-195°C.

Description

Technical Field

[0006] , , , ,

[0001] The present invention relates to a method for roasting coffee beans over charcoal, which can produce roasted coffee beans having a good aroma while using low-temperature roasting to suppress damage to trigonelline contained in green coffee beans.

Background Art

[0002] Green coffee beans contain the nutrient component "trigonelline", and in recent years, "trigonelline" has attracted attention because it can provide effects such as activation of brain nerves, increase in concentration, and suppression of dementia.

[0003] However, the nutrient component "trigonelline" contained in green coffee beans decreases in content due to heating during roasting, and in particular, it is known that thermal decomposition proceeds rapidly around 200°C.

[0004] In order to solve such problems, a method for producing roasted coffee beans with suppressed decomposition of trigonelline has been disclosed, characterized in that the roasting temperature in the roasting machine is 100 to 250°C and the integrated roasting temperature is within 3250°C. In Table 1, in the case of roasting over charcoal, roasting is terminated at a maximum of 170°C (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, as described in the above patent document, if roasting is stopped when the temperature inside the kiln rises to about 170°C, the roasting is stopped at the initial stage when the flavor components of the coffee beans have just begun to be generated by chemical changes due to heating (so-called very light roast). Coffee extracted from these very light roasted beans will have a very weak coffee flavor, and a deep taste and richness cannot be obtained.

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

[0008] To solve the above problems, the present invention provides a method for roasting coffee beans, comprising: an input step of adding 15-25 kg of green coffee beans into a charcoal roaster at an input timing when the internal temperature of the roaster, which is being heated by the combustion of charcoal, is higher than the bottom temperature range which includes the bottom temperature; and an end step of ending the roasting of the coffee beans by the combustion of charcoal at an end timing when the internal temperature of the roaster, which has risen after the addition of the green coffee beans has dropped to the bottom temperature, is included in the end temperature range, wherein the rise time range from the bottom timing when the temperature drops 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 good aroma and flavor while suppressing the loss of trigonelline contained in green coffee beans. Furthermore, it also allows for a significant reduction in roasting time.

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

[0011] This type of configuration makes it possible to further develop the aroma and flavor of the coffee beans. [Effects of the Invention]

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

[0013] [Figure 1] Diagram illustrating the structure of the charcoal roasting machine used in this invention. [Figure 2] Diagram illustrating the change in internal temperature of the roasting kiln when roasting coffee beans according to the present invention. [Figure 3] This figure shows the results of a sensory evaluation of coffee extracted from coffee beans produced using the coffee bean roasting method according to the present invention. [Figure 4] This figure shows the results of a sensory test conducted to confirm the effectiveness of the rise time range according to the present invention. [Figure 5] This figure shows the results of a sensory test conducted to confirm the effectiveness of the bottom temperature range according to the present invention. [Figure 6] This figure shows the results of a sensory test conducted to confirm the effectiveness of the finishing temperature range according to the present invention. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below with reference to Figures 1-6.

[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 explained using Figure 1.

[0016] As shown in Figure 1, the charcoal roaster 1 comprises a furnace 2, a charcoal input port 3, a kiln 4, a bean input port 5, a bean discharge port 6, and an exhaust port 7.

[0017] Coal is fed into the furnace 2 through the coal inlet 3.

[0018] The kiln 4 is located above the furnace 2. The green coffee beans fed into the kiln 4 through the bean inlet 5 are roasted by being heated by the combustion of the coal fed into the furnace 2.

[0019] During roasting, it is common to close the coal inlet 3. That is, during roasting, in principle, no additional coal is added or removed, and roasting is performed by the continuous combustion of the coal initially fed in.

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

[0021] The exhaust port 7 is for exhausting the inside of the kiln 4, and it is possible to adjust the temperature inside the kiln 4 by adjusting the exhaust volume.

[0022] Next, using Fig. 2, the temperature change inside the kiln 4 when roasting coffee beans using the charcoal roaster 1 will be described.

[0023] First, before the green coffee beans are loaded, the temperature inside the kiln is raised by the combustion of the coal loaded into the furnace 2.

[0024] Then, when the green coffee beans are loaded into the kiln 4 (loading timing a), the temperature inside the kiln drops (section A), drops to the bottom temperature (bottom timing b), and then rises again (section B). In section B, the water in the green coffee beans is removed, and then the Maillard reaction occurs. If the water removal is insufficient, "astringency" will appear in the coffee extracted from the produced roasted coffee beans. On the other hand, if the water removal is excessive, the flavor will be lost.

[0025] Then, when the temperature inside the kiln rises to the desired temperature, the operator takes out the roasted coffee beans from the kiln 4 (ending timing c).

[0026] In this invention, in order to suppress the loss of trigonelline contained in green coffee beans, the roasted coffee beans are removed from the roasting oven 4 while the oven temperature is within the completion temperature range (185-195°C) (low-temperature roasting).

[0027] The roasted coffee beans removed from oven 4 need to be cooled down to at least some of their initial heat in a short time (a few minutes) so that the roasting process can be stopped.

[0028] In this way, it is possible to produce roasted coffee beans with a high concentration of trigonelline. However, in conventional charcoal roasting, the roasting was carried out at a low heat for a long time (because section B in Figure 2 was long), which meant that the coffee beans were exposed to heat for an extended period. As a result, the aroma and flavor of the coffee beans were lost, resulting in a lack of deep flavor and body.

[0029] On the other hand, if roasting is done with high heat to shorten the heating time, the temperature will quickly reach the end temperature range (185-195°C), resulting in insufficient moisture removal from the green coffee beans.

[0030] Therefore, the inventor of this invention, after numerous experiments, discovered a method for producing roasted coffee beans with a deep flavor and richness, achieved through low-temperature roasting using charcoal fire while ensuring proper water removal. Below, the process of discovering this manufacturing method is explained 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 dissipate, and if it was shorter than 600 seconds, insufficient water removal would result in a noticeable bitterness. Therefore, we found that section B needs to be included within the rising time range (600-700 seconds).

[0032] Based on the above, section B will be fixed at 600-700 seconds. In this case, if section B starts from a low bottom temperature, roasting will be performed at a high rate of temperature increase, and if section B starts from a high bottom temperature, roasting will be performed at a low rate of temperature increase.

[0033] However, when the bottom temperature was lower than 95°C, the resulting flavor was bland and lacked aroma. This is likely because starting section B at a low temperature caused excessive heat to penetrate the coffee beans, resulting in excessive water removal.

[0034] On the other hand, when the bottom temperature was higher than 110°C, the surface of the coffee beans became excessively burnt, and a bitter taste became pronounced. For proper dehydration to occur, heat must be thoroughly transferred to the inside of the coffee beans, and for this to happen, a period of roasting at a moderate temperature is necessary. However, when the bottom temperature was higher than 110°C, it is thought that the heat was not properly transferred to the inside of the coffee beans because section B started at a high temperature, resulting in insufficient dehydration.

[0035] From the above, it was found that in order to produce roasted coffee beans with good aroma and flavor while retaining a large amount of trigonelline, the bottom temperature must fall within the bottom temperature range (95-110°C), and the internal temperature of the roaster must reach the final temperature range (185-195°C) within the rise time range (600-700 seconds).

[0036] It is possible to achieve the following by adjusting the type and amount of charcoal used and the exhaust port 7: "The bottom temperature falls within the bottom temperature range (95-110°C), and the internal temperature of the kiln reaches the end temperature range (185-195°C) within the rise time range (600-700 seconds) from there."

[0037] Furthermore, for the bottom temperature to fall within the bottom temperature range (95-110°C), the internal temperature of the roaster 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 this application discovered that when the temperature rises from the bottom temperature to a finishing temperature range (165-185°C) lower than the end temperature range (185-195°C) (finishing timing d in Figure 2), performing a finishing process that reduces the rate of increase in the internal temperature of the roaster while preventing the internal temperature from decreasing further develops the aroma and flavor of the coffee beans. This is thought to be due to the fact that calming the heating of the coffee beans at the end of roasting promotes chemical reactions within the coffee beans.

[0039] To reduce the rate of temperature rise inside the kiln, one possible approach is to increase the exhaust volume from the exhaust port 7.

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

[0041] Furthermore, when the amount of coffee beans used 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] Based on the above, by using the coffee bean roasting method of the present invention, it was possible to produce roasted coffee beans with good aroma and flavor while using low-temperature roasting to suppress the damage of trigonelline contained in green coffee beans.

[0043] The present invention will be described in detail below based on examples. (Example 1) The internal temperature of the charcoal roaster (FUJI ROYAL COFFEE ROASTER TYPE R-130 30kg charcoal roaster (Fuji Coffee Machinery Co., Ltd.)) was increased by burning binchotan charcoal. At the point when the internal temperature reached 118°C, 20kg of "Brazil Amarelo Bourbon" green coffee beans were added to the roaster. After 1 minute and 27 seconds, the internal temperature reached the bottom temperature (99°C), and the internal temperature began to rise again. Subsequently, when the internal temperature reached 180°C, the oven was vented to reduce the rate of temperature increase. At the end of the process, when the internal temperature reached 189°C, the roasted coffee beans were removed from the roaster. The removed coffee beans were cooled for several minutes on a cooling machine installed in the charcoal roaster. The time taken from reaching the bottom temperature to removing the roasted coffee beans was 10 minutes and 26 seconds (626 seconds). The time taken from the moment the green coffee beans were added to the machine until they were removed was 11 minutes and 53 seconds.

[0044] When the roasted coffee beans produced in this manner were analyzed for "trigonelline" content at the Japan Food Research Laboratories, it was found that they contained more than four times the amount of "trigonelline" compared to the applicant's existing product, "Brazil Bourbon Coffee Shake-Bag," which is also made from the same "Brazil Amarelo Bourbon" green coffee beans, although it is not roasted at a low temperature. In other words, the roasted coffee beans produced by this invention contained more than four times the amount of "trigonelline" compared to those roasted using conventional methods (roasting at a higher temperature than low temperature).

[0045] Furthermore, five panelists conducted a sensory evaluation of the aroma and flavor of the coffee extracted from the roasted coffee beans produced in the above process, using a five-point scale (5: very good, 4: good, 3: average, 2: not very good, 1: not good). As shown in Figure 3, all five panelists gave a high rating of "5," with comments such as, "A rich and full-bodied aroma spreads while being enveloped in a sweetness that evokes nutty flavors and brown sugar, and a soft richness."

[0046] Figures 4-6 show the results (average values ​​of 5 people) of sensory evaluations of flavor on a 5-point scale (5: very good, 4: good, 3: average, 2: not very good, 1: not good) conducted by varying the values ​​of the "rise time range," "bottom temperature range," and "finishing temperature range" discovered above, in order to confirm their effectiveness. Except for the items that were changed, the sensory evaluations were conducted under substantially the same conditions as those described in the above example.

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

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

[0049] Figure 6 shows the results of a sensory evaluation when roasting was performed with a different "finishing temperature range." In the range of "165-185°C," all five participants gave a rating of "5."

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

[0051] Furthermore, while it typically takes nearly 30 minutes to roast coffee beans (medium roast) using low-temperature roasting over charcoal, as shown in Table 1 of Patent Document 1, the present invention allows for the entire process, from adding the green coffee beans to roasting them over charcoal, to be completed in less than 12 minutes (11 minutes and 53 seconds in the above embodiment), significantly reducing the roasting time. 1. Charcoal roaster 2 furnace 3 Charcoal inlet 4 kiln 5 Bean inlet 6 Bean outlet 7 Exhaust vent Section A Section B a. Timing of input b. Bottom timing c. End timing d Finishing timing

Claims

1. The process involves adding 15-25 kg of green coffee beans to the charcoal roaster at a timing when the internal temperature of the roaster, which is being heated by the combustion of charcoal, is higher than the bottom temperature range which includes the bottom temperature. The roasting process ends when the temperature inside the kiln, which has risen after the coffee beans have been added and has dropped to the bottom temperature, falls within the end temperature range, and the roasting of the coffee beans by burning the charcoal is terminated. Equipped with, The time range for the temperature to rise from the bottom timing (when the temperature drops to the bottom temperature) to the end timing is 600-700 seconds. The aforementioned bottom temperature range is 95-110°C. The aforementioned termination temperature range is 185-195°C. A method for roasting coffee beans, characterized by the following:

2. The kiln temperature is further comprising a finishing step that reduces the rate of increase in the kiln temperature within a range where the kiln temperature does not decrease when the kiln temperature rises from the bottom temperature to a finishing temperature range lower than the end temperature range. The method for roasting coffee beans according to claim 1, characterized in that the finishing temperature range is 165-185°C.

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