Coffee bean roasting device and coffee bean roasting method

Abstract

To provide a method for roasting and producing coffee beans, capable of roasting coffee beans at a roasting temperature equivalent to that obtained by a conventional hydrocarbon fuel burner, and producing a different taste. [Solution] A coffee bean roasting and production method in which coffee beans are roasted with hot air generated by a hydrogen-mixed combustion burner includes a control step of controlling the heat power of the hydrogen-mixed combustion burner so that the hot air temperature at the start of roasting is higher than the hot air temperature during other parts of the roasting period.

Description

[Technical field]

[0001] The present invention relates to a coffee bean roasting device and a method for roasting and producing coffee beans. [Background technology]

[0002] Examples of heat sources for generating hot air in typical coffee bean roasting devices include burners that burn natural gas, liquefied petroleum gas, wood, etc., as well as heat sources such as electric heaters, halogens, infrared rays, and microwaves (see, for example, Patent Documents 1 and 2).

[0003] Examples of burners include burners equipped with nozzles for supplying one type of fuel and one type of oxidizer, and multi-fuel burners equipped with nozzles for supplying multiple types of fuel (hydrogen, city gas) and one type of oxidizer (air) (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2022-537262 [Patent Document 2] Patent No. 6173395 [Patent Document 3] Patent No. 7064474 Summary of the Invention [Problem to be solved by the invention]

[0005] Burners that use hydrocarbon fuels such as city gas as a heat source for generating hot air inevitably generate carbon dioxide. Therefore, as a measure against global warming, it is expected that coffee bean roasters will also suppress the generation of carbon dioxide. In addition, although the above-mentioned co-firing burner discloses the use of hydrogen, its use in coffee bean roasters is not disclosed.

[0006] While there is a demand to create a taste equivalent to that of coffee beans roasted with a hydrocarbon fuel burner, there is also a demand to create the unique taste that comes from roasting with a hydrogen co-fuel burner.

[0007] The present disclosure provides a coffee bean roasting device and a method for roasting and producing coffee beans that can roast coffee beans at a hot air temperature equivalent to that of a conventional hydrocarbon fuel burner, thereby creating a different taste. [Means for solving the problem]

[0008] The coffee bean roasting device (1) is An adjustable hydrogen co-fuel burner (10) using hydrogen and a hydrocarbon fuel and having a turndown ratio of 1:10 or more; A roaster (20) that uses hot air generated by the hydrogen-mixed combustion burner as a heat source for roasting; A control device (30) is provided that controls the heat power of the hydrogen-mixed combustion burner so that the hot air temperature at the start of roasting is higher than the hot air temperatures during other roasting periods (in a roasted bean temperature curve over the entire roasting period that is convex downward). The "roasted bean temperature" is the temperature of the coffee beans roasted with the hot air from the hydrogen-mixed combustion burner (10) (or the surrounding atmosphere temperature). Examples of "hydrocarbon fuels" include city gas, propane gas, and ethane gas. A "hydrogen-mixed burner" may use only hydrogen fuel. The "roaster" may be a hot air roaster or a semi-hot air roaster. The "controller" may be executing control of the roaster and / or control of the hydrogen co-fuel burner. Roasting may start when the coffee beans start to be added or when the entire amount has been added. The hot air temperature may be the hot air temperature inside the roaster or the temperature of the hot air sent to the roaster. The hot air temperature at the start of roasting may be at least 1%, at least 4%, or at least 6% higher than the hot air temperature during the rest of the roasting period. The hot air temperature is, for example, more than 400° C. at the start of roasting, and is preferably 420° C. or higher, 430° C. or higher, 440° C. or higher, or 450° C. or higher. By increasing the hot air temperature at the start of roasting, the roasting period can also be made shorter than that of normal roasting or low-temperature roasting.

[0009] The coffee bean roasting device (1) may include a bean temperature measuring device (45) for measuring the temperature of the roasted beans (or the surrounding atmosphere temperature) during roasting. The control device (30) may control the heat power of the hydrogen-mixed combustion burner (10) so that the roasted bean temperature (CPV_t) measured by the bean temperature measuring device (45) corresponds to a preset roasted bean temperature profile (roasted bean temperature set value data (CSV_t)). The roasted bean temperature is, for example, preferably above 180°C and below 240°C at the start of roasting. The bean temperature measuring device (45) may be a thermometer that measures the temperature by contacting the coffee beans, or a non-contact thermometer.

[0010] The coffee bean roasting apparatus (1) may include a hot air temperature measuring device (40) for measuring the temperature of the hot air generated by the hydrogen-mixed combustion burner (10). The control device (30) may control the heat power of the hydrogen-mixed combustion burner (10) so that the hot air temperature (HPV_t) measured by the hot air temperature measuring device (40) corresponds to a preset hot air roasting profile (hot air temperature set value data (HSV_t) for roasting). One or more of the hot air temperature measuring devices (40) may be provided on any hot air supply pipe before roasting, pipe inside the roaster, or hot air exhaust pipe after roasting.

[0011] When one of the roasted bean temperature profile and the hot air roasting profile is set, the other may be set in association with it. The roasted bean temperature profile and the hot air roasting profile may be set in a plurality of types according to the type of roasting, the type of beans (including the place of production, the year of production, etc.), the amount of roasting, etc. The roasted bean temperature profile and the hot air roasting profile may be stored in a memory of the device (1) or the control device (30). The profiles may be sent from an external device. The device (1) may have a profile setting unit that sets the roasting profile.

[0012] The roasted bean temperature profile and the hot air roasting profile are set to provide a roasted bean temperature curve during roasting that can achieve the desired taste. In the present invention, a roasted bean temperature curve that is the same as or cannot be achieved with a conventional 100% natural gas burner can be achieved. The roasted bean temperature curve is a downward convex curve, and when it is divided into three parts, the early stage of roasting, the middle stage of roasting, and the late stage of roasting, the hot air temperature at the start of roasting in the early stage of roasting has a higher value than those in the other roasting periods. The temperature at the start of roasting in the early stage of roasting may be the maximum value. For example, at the start of roasting, the roasted bean temperature is set to a maximum value between 180°C and 240°C, the temperature is gradually decreased from the start of roasting to a minimum value in the middle of roasting with a downward convexity, and the temperature is gradually increased from the middle to the later stages of roasting. In the approximate curve of the roasted bean temperature that is convex downward between the start point and the end point of roasting, the period from the start point (maximum value) to the first intermediate point (midpoint in roasting time or midpoint in temperature), which is the midpoint between the start point and the nadir (minimum value), may be defined as the early stage of roasting, the period from the first intermediate point to the second intermediate point (midpoint in roasting time or midpoint in temperature), which is the midpoint between the nadir (minimum value) and the end point of roasting, may be defined as the middle stage of roasting, and the period from the second intermediate point to the end point of roasting may be defined as the late stage of roasting. Although the high-temperature roasting period using the hydrogen burner of the present invention is the same as that using a conventional hydrocarbon-based fuel burner, it can achieve a different taste.

[0013] The hydrogen-mixed combustion burner (10) may include a burner body (11), a burner tip (12), a hydrogen supply nozzle (13) arranged inside the burner body (11) and having a nozzle tip with a circular cross section for supplying hydrogen, an oxidizer supply nozzle (14) arranged inside the burner body (11) and provided outside the hydrogen supply nozzle and having a ring-shaped cross section for supplying an oxidizer (e.g., air, oxygen), and a fuel supply nozzle (15) arranged inside the burner body and provided outside the oxidizer supply nozzle and having a ring-shaped cross section for supplying a hydrocarbon-based fuel. The hydrogen-mixed combustion burner (10) may include a hydrogen source (S2) (e.g., a main pipe, a cylinder, a cylinder) of a predetermined pressure, a hydrogen pipe (L2), a valve (V2) (e.g., a control valve, a gate valve) provided in the hydrogen pipe (L2), an optional gas flow meter, an optional gas pressure gauge, an oxidizer source (S1) (e.g., a main pipe, a cylinder, a compression pump, a compressor) of a predetermined pressure, an oxidizer pipe (L1), a valve (V1) (e.g., a control valve, a gate valve) provided in the oxidizer pipe (L1), an optional gas flow meter, an optional gas pressure gauge, a hydrocarbon fuel source (S3) (e.g., a main pipe, a cylinder, a cylinder) of a predetermined pressure, a hydrocarbon fuel pipe (L3), a valve (V3) (e.g., a control valve, a gate valve) provided in the hydrocarbon fuel pipe (L3), an optional gas flow meter, and an optional gas pressure gauge. The control device (30) may adjust the valve opening of one or more valves among a valve provided in the hydrogen pipe (L2), a valve provided in the oxidizer pipe (L1), and a valve provided in the hydrocarbon fuel pipe (L3) to control the combustion power (heating power) (control the mixed combustion ratio). The control device (30) may proportionally control the valve opening in response to an increase or decrease in the combustion power (heating power).

[0014] The hydrogen-mixed combustion burner (10) may include a circulation pipe (L10) for circulating hot air (waste gas) from the burner tip to the oxidizer pipe (L1), a suction pump (P10) provided in the circulation pipe (L10), a valve (e.g., a control valve, a gate valve) provided in the circulation pipe (L10), an optional gas flow meter, and an optional gas pressure gauge. The control device (30) may control the amount of circulation of hot air (waste gas) by adjusting the drive of a suction pump (P10) provided in the circulation pipe (L10) and the opening of a valve (V10) (e.g., a control valve, a gate valve) provided in the circulation pipe (L10).

[0015] The coffee bean roasting device (1) may comprise a storage device (31) for storing the roasting profile.

[0016] Coffee bean roasting method: A coffee bean roasting and manufacturing method in which coffee beans are roasted with hot air generated by an adjustable hydrogen-mixed combustion burner with a turndown ratio of 1:10 or more, the method including a control step of controlling the heat power of the hydrogen-mixed combustion burner so that the hot air temperature at the start of roasting is higher than the hot air temperatures during other roasting periods (in a roasted bean temperature curve over the entire roasting period that is convex downward). The control step may control the heat power of the hydrogen-mixed combustion burner (10) so that the roasted bean temperature (CPV_t) measured by the bean temperature measuring device (45) corresponds to a preset roasted bean temperature profile (roasted bean temperature set value data (CSV_t)). The control step may control the heat power of the hydrogen-mixed combustion burner (10) so that the hot air temperature (HPV_t) measured by the hot air temperature measuring device (40) corresponds to a preset hot air roasting profile (hot air temperature set value data (HSV_t) for roasting). The control step may control the combustion power (heat power) (control the mixed-fuel ratio) by adjusting the valve opening of one or more valves among a valve provided in a hydrogen pipe, a valve provided in an oxidizer pipe, and a valve provided in a hydrocarbon fuel. The control step may control the amount of the waste gas circulated by adjusting the drive of a suction pump provided in the circulation pipe and the opening degree of a valve provided in the circulation pipe.

[0017] "Coffee beans" includes all coffee beans, regardless of origin (brand) or type.

[0018] The control device (30) may be configured as an information processing device (e.g., a computer, a server) having a memory, a processor, a software program, a dedicated circuit, firmware, etc. The information processing device may be either on-premise or cloud, or a combination of both.

[0019] (effect) (1) The hydrogen-mixed combustion burner reproduces the same hot air temperature as that of roasting equipment that uses hydrocarbon fuels such as natural gas, making it possible to create flavors that are different from conventional ones. (2) By using 100% hydrogen fuel, hot air is generated without any carbon dioxide. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a diagram showing an example of a coffee bean roasting device of embodiment 1. [Diagram 2] FIG. 2 is a diagram showing an example of the structure of a multi-fuel burner. [Diagram 3] FIG. 2 is a diagram showing an example of a piping configuration of a multi-fuel burner. [Figure 4] FIG. 2 is a diagram showing an example of a roasted bean temperature curve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] (Embodiment 1) Figure 1 shows an example of the function of the coffee bean roaster 1 of the first embodiment. Figure 2 shows an example of the structure of a multi-fuel burner. Figure 3 shows an example of the piping configuration of a multi-fuel burner. Figures 1 to 3 show examples of the configuration and function, and are not limited thereto, and various configuration changes are possible.

[0022] Coffee bean roasting apparatus 1 includes a hydrogen-mixed combustion burner 10, a roaster 20, a control device 30, a storage device 31, a hot air temperature measuring device 40, and a bean temperature measuring device 45.

[0023] The hydrogen-mixed burner 10 uses hydrogen and hydrocarbon fuel and has an adjustable burner function with a turndown ratio of 1:10 or more. It is also possible to stop the supply of hydrocarbon fuel and supply only hydrogen fuel. The turndown ratio is 1:10 or more, but 1:15 or 1:20 is preferable. In this embodiment, the hydrocarbon fuel is compressed natural gas, but is not limited to this. The hydrogen fuel is compressed hydrogen at 0.1 MPa. The oxidizer is air.

[0024] The structure of the hydrogen-mixed combustion burner 10 will be described with reference to FIG. 2. The hydrogen-mixed combustion burner 10 includes a burner body 11 and a burner tip 12. The opening area of ​​the burner tip 12 increases toward the tip. Inside the burner body 11, there are formed a hydrogen supply nozzle 13 with a nozzle tip having a circular cross section that supplies hydrogen, an oxidizer supply nozzle 14 with a ring cross section that is provided outside the hydrogen supply nozzle 13 and supplies air, and a fuel supply nozzle 15 with a ring cross section that is provided outside the oxidizer supply nozzle 14 and supplies compressed natural gas. The structure is such that the hydrogen fuel and natural gas are not brought into direct contact with each other, but rather an oxidizer is injected between them to form a mixing region suitable for each fuel.

[0025] The roaster 20 uses the hot air generated by the hydrogen-mixed combustion burner 10 as a heat source for roasting. The roaster 20 of this embodiment is a drum-type hot air roaster or a fluidized bed-type hot air roaster.

[0026] The controller 30 controls the heat of the hydrogen-mixed combustion burner so that the hot air temperature at the start of roasting is higher than the hot air temperatures in the other roasting periods in the downwardly convex roasted bean temperature curve for the entire roasting period. In this embodiment, the controller 30 controls the heat of the hydrogen-mixed combustion burner 10 so that the roasted bean temperature (CPV_t) measured by the bean temperature measuring device 45 corresponds to a preset roasted bean temperature profile (roasted bean temperature set value data (CSV_t)). The control device 30 controls the heat of the hydrogen-mixed combustion burner 10 so that the hot air temperature (HPV_t) measured by the hot air temperature measuring device 40 corresponds to a preset hot air roasting profile (hot air temperature setting value data (HSV_t) for roasting).

[0027] The storage device 31 stores a roasting profile 311. The roasted bean temperature and hot air roasting profile 311 includes roasted bean temperature set value data (CSV_t) and hot air temperature set value data (HSV_t) according to the roasting time linked to the bean type and roasting conditions.

[0028] The piping configuration of the hydrogen-mixed combustion burner 10 will be described with reference to Figure 3. The hydrogen-mixed combustion burner 10 includes a 0.1 MPa compressed hydrogen cylinder S2, a hydrogen pipe L2, a flow control valve V2 with a flow meter provided on the hydrogen pipe L2, an air compression pump P, an air pipe L1, a flow control valve V1 with a flow meter provided on the air pipe L1, a compressed natural gas cylinder S3, a natural gas pipe L3, and a flow control valve V3 with a flow meter provided on the natural gas pipe L3.

[0029] The hydrogen-mixed combustion burner 10 is equipped with a circulation pipe L10 for circulating hot air (waste gas) from the burner tip 12 to the air pipe L1, a suction pump P10 provided in the circulation pipe L10, and a flow rate control valve with a flow meter provided in the circulation pipe L10. The temperature measuring device 40 is provided in the hot air supply pipe before roasting. The temperature measuring device 40 measures the temperature of the hot air generated by the hydrogen-mixed combustion burner 10. The hot air from the hydrogen-mixed combustion burner 10 is sent to the fluidized bed 21 of the roaster 20. The bean temperature measuring device 45 provided in the fluidized bed 21 is a contact thermometer that measures the temperature of the coffee beans being roasted in the fluidized bed 21.

[0030] The burner control unit 101 of the hydrogen-mixed combustion burner 10 can control combustion (proportional control of fuel supply amount and air supply amount) in response to the roasted bean temperature, the hot air roasting profile 311, and commands from the control device 30. The control device 30 may instruct and control the burner control unit 101 of the hydrogen-mixed combustion burner 10 so that the measured temperature (HPV_t) measured by the hot air temperature measuring device 40 corresponds to the roasted bean temperature and the hot air roasting profile 311. The control device 30 may instruct and control the burner control unit 101 of the hydrogen-mixed combustion burner 10 so that the measured temperature (CPV_t) measured by the roasted bean temperature measuring device 45 corresponds to the roasted bean temperature and the hot air roasting profile 311.

[0031] The control device 30, directly or by issuing a command to the burner control unit 101, adjusts the valve opening of one or more of the flow control valves V2 installed in the hydrogen pipe L2, the flow control valve V1 installed in the air pipe L1, and the flow control valve V3 installed in the natural gas pipe L3, thereby controlling the combustion power (thermal power). It can control the ratio of the supply amounts of hydrogen and natural gas, and the air amount. It can proportionally control the opening of each valve according to the increase or decrease in the combustion power (thermal power).

[0032] The control device 30 can control the start / stop of circulation of hot air (waste gas) and the circulation amount by adjusting the drive of the suction pump P10 provided in the circulation pipe L10 and the valve opening of the flow rate control valve V10 provided in the circulation pipe L10, either directly or by issuing a command to the burner control unit 101. When the combustion power (fire power) is to be reduced, the circulation can be started or the circulation amount can be increased to control the reduction of the oxygen concentration supplied to the burner. This can also reduce the amount of NOx generated.

[0033] According to this embodiment, the mixture ratio of hydrogen and hydrocarbon fuel can be freely set in the multi-fuel burner. A high turndown ratio can be used in the hydrogen burner, and new profiles (roasted bean temperature curve, hot air temperature curve) equivalent to those of conventional hydrocarbon fuel burners can be designed. Even with the same roasted bean temperature profile or hot air roasting profile, a different taste can be created from that of a natural gas burner. Examples of "taste" include sourness, richness, bitterness, aroma (fragrance), etc. Since aroma stimulates the sense of smell, this can also be said to be an improvement in the sense of smell.

[0034] (Example 1: Medium roast) We will explain Example 1 and Comparative Example 1, which are high-temperature roasting using the hydrogen-mixed combustion burner in embodiment 1, Comparative Examples 2 and 3, which are normal roasting, and Comparative Examples 4 and 5, which are low-temperature roasting. Coffee beans: 5kg Roast degree: Medium roast High-temperature roasting time: 9 minutes (Example 1, Comparative Example 1) Normal roasting time: 14 minutes (Comparative examples 2 and 3) Low-temperature roasting time: 20 minutes (Comparative Examples 4 and 5) Hot air temperature at the start of high-temperature roasting: 450°C (Example 1, Comparative Example 1) Hot air temperature at the start of normal roasting: 400°C (Comparative Examples 2 and 3) Hot air temperature at the start of low-temperature roasting: 280°C (Comparative Examples 4 and 5) Heat source used: Hydrogen 0.1MPa : Natural gas 10kPa (0.01MPa) Hydrogen only (Example 1, Comparative Examples 2 and 4): 100% hydrogen Natural gas (Comparative Examples 1, 3, and 5): 100% natural gas Supply pressure: 10kPa

[0035] Figure 4 shows an example of the roasted bean temperature curves during high-temperature, normal, and low-temperature roasting. The same roasting temperature curve was used for Example 1 and Comparative Example 1, which were high-temperature roasting (450°C). The same roasting temperature curve was also used for Comparative Examples 2 and 3, which were normal roasting (400°C), and Comparative Examples 4 and 5, which were low-temperature roasting (280°C). The roasted bean temperature was measured by directly contacting the beans during roasting.

[0036] (Taste evaluation) Example 1 and Comparative Examples 1 to 5 were each subjected to a taste evaluation. The method for obtaining the extract is as follows. Extraction method: Paper drip method Extraction conditions: 20g coffee powder, 320g hot water, 20 seconds steeping time Sensory evaluation The extracted samples were blinded and absolute evaluation was carried out according to the following sensory evaluation criteria: The taste intensity of five items (sourness, bitterness, astringency, richness, and aftertaste) was rated on a nine-level scale (ranging from -4 (very weak) to +4 (very strong), with the median value 0 being normal). Subjects: 16 people for Example 1, Comparative Examples 1, 4, and 5 : Comparative Examples 2 and 3: 14 people The roast level (L value) of the roasted coffee beans was evaluated using a colorimeter (ZE-6000, manufactured by Nippon Denshoku Industries Co., Ltd.). The evaluation results are shown in Table 1.

[0037] [Table 1]

[0038] In the evaluation results in Table 1, a significance test (t-test: significance level 5%) was conducted for Example 1 using the roasted product of Comparative Example 1 (natural gas) as the standard. The results showed that Example 1 had a stronger sour taste than Comparative Example 1. No significant difference was confirmed between Comparative Examples 2 and 3, which were normally roasted (400°C), and Comparative Examples 4 and 5, which were low-temperature roasted (280°C).

[0039] (Example 2: Light roast) Example 2 was carried out under light roasting conditions. Coffee beans: 5kg Roast degree: Light roast High-temperature roasting time: 8 minutes (Example 2, Comparative Example 6) Normal roasting time: 11 minutes (Comparative examples 7 and 8) Hot air temperature at the start of high-temperature roasting: 450°C (Example 2, Comparative Example 6) Hot air temperature at the start of normal roasting: 400°C (Comparative Examples 7 and 8) Heat source used: Hydrogen 0.1MPa : Natural gas 10kPa (0.01MPa) Hydrogen only (Example 2, Comparative Example 7): 100% hydrogen Natural gas (Comparative Examples 6 and 8): 100% natural gas

[0040] The taste evaluation and roast level evaluation were performed in the same manner as in Example 1. Table 2 shows the evaluation results. Subjects: 14 people in Example 2 and Comparative Example 6 Comparative Examples 7 and 8: 16 people

[0041] [Table 2]

[0042] In the evaluation results in Table 2, a significance test (t-test: significance level 5%) was performed for Example 2 using the roasted product of Comparative Example 6 (natural gas) as the standard. The results showed that Example 2 had a weaker aftertaste than Comparative Example 6. No significant difference was confirmed between Comparative Examples 7 and 8, which were normally roasted (400°C).

[0043] (Example 3: Deep-fried) Example 3 was carried out under dark roasting conditions. Coffee beans: 5kg Roast level: dark roast High-temperature roasting time: 9 minutes (Example 3, Comparative Example 9) Normal roasting time: 13 minutes (Comparative examples 10 and 11) Hot air temperature at the start of high-temperature roasting: 450°C (Example 3, Comparative Example 9) Hot air temperature at the start of normal roasting: 400°C (Comparative Examples 10 and 11) Heat source used: Hydrogen 0.1MPa : Natural gas 10kPa (0.01MPa) Hydrogen only (Example 3, Comparative Example 10): 100% hydrogen Natural gas (Comparative Examples 9 and 11): 100% natural gas

[0044] The taste evaluation and roast level evaluation were performed in the same manner as in Example 1. Table 3 shows the evaluation results. Subjects: 14 people in Example 3 and Comparative Example 9 Comparative Examples 10 and 11: 16 people

[0045] [Table 3]

[0046] In the evaluation results in Table 3, a significance test (t-test: significance level 5%) was performed for Example 3 using the roasted product of Comparative Example 9 (natural gas) as the standard. The results showed that Example 3 had a weaker bitterness than Comparative Example 9. No significant difference was confirmed between Comparative Examples 10 and 11, which were normally roasted (400°C).

[0047] Even with the same roasted bean temperature curve, the hydrogen burner was able to create a different taste. We believe this is due to the high energy of superheated steam. When superheated steam is cooled by the temperature difference with the heated object and attempts to return to water, the "heat of condensation" that is generated has a large amount of energy, and we believe it also has excellent thermal conductivity (energy transfer to the heated object is about 1.2 times). The hot air obtained from a hydrogen burner contains about twice as much superheated steam (compared to natural gas) as the hot air obtained from a natural gas burner with the same heat capacity, and is thought to be more strongly affected by the superheated steam. In other words, in the Examples, the dewatering (drying) process at the beginning of roasting can proceed more quickly than in the Comparative Examples, which is thought to have contributed to a longer time for flavor development and the creation of a different flavor.

[0048] (method) The coffee bean roasting production method roasts coffee beans with hot air generated by an adjustable hydrogen-mixed combustion burner with a turndown ratio of 1:10 or more, and includes a control step of controlling the heat power of the hydrogen-mixed combustion burner so that the hot air temperature at the start of roasting is higher than the hot air temperatures during other roasting periods in a downwardly convex roasted bean temperature curve over the entire roasting period. The control step may control the heat power of the hydrogen-mixed combustion burner 10 so that the roasted bean temperature (CPV_t) measured by the bean temperature measuring device 45 corresponds to a preset roasted bean temperature profile (roasted bean temperature set value data (CSV_t)). The control step may control the combustion power (heat power) (control the mixed-fuel ratio) by adjusting the valve opening of one or more valves among a valve provided in a hydrogen pipe, a valve provided in an oxidizer pipe, and a valve provided in a hydrocarbon fuel. The control step may control the amount of the waste gas circulated by adjusting the drive of a suction pump provided in the circulation pipe and the opening degree of a valve provided in the circulation pipe. The control step may control the combustion power (heat power) (control the mixed-fuel ratio) by adjusting the valve opening of one or more valves among a valve provided in the hydrogen piping, a valve provided in the oxidizer piping, and a valve provided in the hydrocarbon fuel. The control step may control the amount of circulated waste gas by adjusting the drive of a suction pump provided in the circulation pipe and the opening degree of a valve provided in the circulation pipe. [Explanation of symbols]

[0049] 1 Coffee bean roasting equipment 10 Hydrogen mixed combustion burner 20 Roaster 30 Control device 31 Storage device 40 Hot air temperature measuring device 45 Bean temperature measuring device

Claims

1. A method for roasting coffee beans by using hot air generated by a hydrogen-mixed combustion burner, comprising: Hydrogen gas is used as fuel for the hydrogen-mixed combustion burner, A control step of controlling the heat of the hydrogen-mixed combustion burner so that the hot air temperature at the start of roasting is at least 450°C. Coffee bean roasting production method.

2. The method for roasting coffee beans according to claim 1, wherein the roasted bean temperature is set to a maximum value between 180°C and 240°C at the start of roasting, the temperature is gradually decreased from the start of roasting to a minimum value with a downward convex shape in the middle of roasting, and the temperature is gradually increased from the middle to the later stages of roasting.

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