Coffee bean roasting methods

Abstract

This invention provides a coffee bean roasting method that improves flavor, aroma, and extraction efficiency by moderately heating and pressurizing the coffee beans and rapidly changing the pressure applied to them, thereby actively altering the internal tissue structure of the coffee beans. [Solution] The coffee bean roasting method includes the steps of: placing coffee beans in a container and heating and pressurizing them; creating an atmosphere of steam at a predetermined temperature T1 and a predetermined pressure inside the container, and then rapidly reducing the pressure to atmospheric pressure; and heating the coffee beans to a predetermined temperature T2 without pressurizing them, wherein the predetermined temperature T1 and the predetermined temperature T2 are T1

Description

Technical Field

[0001] The present invention relates to a method for roasting coffee beans, which includes a step of moderately heating and pressurizing coffee beans and rapidly changing the pressure applied to the coffee beans.

Background Art

[0002] Coffee beans are slowly heated using a roasting machine, and the taste and aroma are brought out by chemical changes (Maillard reaction and caramelization) inside the coffee beans. In order to enjoy coffee with a good flavor, it is necessary to appropriately roast the coffee beans. Normal roasting of coffee beans simply involves applying heat and does not include steps of changing pressure such as pressurization or depressurization. However, it has been confirmed that by applying a change in pressure during heating, the internal tissue structure of coffee beans can be changed, which affects the flavor and extraction efficiency after roasting. Therefore, conventionally, roasting apparatuses and roasting methods for coffee beans including pressurization or depressurization have been developed.

[0003] Patent Document 1 discloses a method for roasting coffee beans in which the coffee beans in a container are heated while being stirred and roasted under pressure. In particular, it is described that the maximum pressure during roasting is set within the range of 1.5 to 5 atmospheres. According to this method, it is said that the extraction efficiency of coffee components is improved and the flavor can be significantly enhanced.

[0004] Patent Document 2 describes that coffee beans or coffee beans immersed in water are housed in a crusher, and the coffee beans are pressurized and steamed in an atmosphere of steam with a pressure of 3 kg / cm 2 G or more and 60 kg / cm 2 G or less to hydrolyze the components inside the coffee beans, and then the coffee beans are opened to atmospheric pressure and crushed, and the coffee components in the crushed coffee beans are extracted with a solvent. According to this invention, roasting and pulverization of coffee beans can be performed in one step. Also, it is said that the coffee beans are micronized by crushing and the extraction rate of coffee components is improved.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2005-137304 [Patent Document 2] Japanese Patent Application Publication No. 5-168410 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The coffee bean roasting method described in Patent Document 1 uses a device that heats coffee beans in a pressure-resistant container while stirring, and after the temperature rises and the pressure inside the container reaches a predetermined level (1.5 to 5 atmospheres), it is adjusted to maintain that predetermined pressure, allowing the coffee beans to be roasted until they reach a predetermined roasting temperature (195 to 235°C). However, depending on the type of coffee bean, 5 atmospheres may not be sufficient. Furthermore, using such a device incurs costs for manufacturing and maintenance due to its complexity. Therefore, it is desirable to use a device with a simpler structure, especially an existing device.

[0007] The invention described in Patent Document 2 improves the extraction rate of coffee beans through explosion, but because the coffee beans are pulverized, it is suitable for cases where coffee is to be brewed immediately, but not for cases where it is not to be brewed immediately or when roasted coffee beans need to be stored. In order to obtain coffee beans with good flavor and extraction efficiency, it is necessary to remove the coffee beans after applying pressure before they explode.

[0008] In view of the above problems, the present invention provides a method for roasting coffee beans that improves flavor, aroma, and extraction efficiency by moderately heating and pressurizing the coffee beans and rapidly changing the pressure applied to the coffee beans, thereby actively altering the internal tissue structure of the coffee beans. [Means for solving the problem]

[0009] To solve the above problems, the coffee bean roasting method of the present invention is:A roasting method for roasting coffee beans using a grain expansion processing device, the same as above coffee beans The aforementioned grain expansion processing apparatus Put it in, While rotating the container The steps of heating and pressurizing, and the Grain expansion processing equipment Inside Set the temperature to 175-185℃ and Pressure approximately 1 MPaG The process involves placing the area in a water vapor atmosphere and then rapidly reducing the pressure to atmospheric pressure. Removed from the aforementioned grain expansion processing apparatus, Without pressurizing the aforementioned coffee beans Continue roasting temperature 220~230℃ The process of heating up to that point This method includes roasting the coffee beans while maintaining their external shape and destroying only the internal structure. It is characterized by the following: [Effects of the Invention]

[0010] According to the coffee bean roasting method of the present invention, the flavor, aroma, and extraction efficiency of the coffee beans can be improved. [Brief explanation of the drawing]

[0011] [Figure 1] This is an explanatory diagram showing the flow of a coffee bean roasting method according to one embodiment of the present invention. [Figure 2] This is a schematic graph showing the relationship between pressure and the initial temperature reached in a coffee bean roasting method according to one embodiment of the present invention. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention (hereinafter abbreviated as "examples") will be described with reference to Figures 1 and 2. Figure 1 is an explanatory diagram showing the flow of the coffee bean roasting method in this embodiment, and Figure 2 is a schematic graph showing the relationship between pressure and the initial temperature reached (the temperature first measured) in that method. This graph is a conceptual visualization and does not guarantee quantitative accuracy. In addition, in this embodiment, gauge pressure (PaG), with atmospheric pressure as the reference pressure of 0, is used as the unit of pressure. Hereinafter, the explanation will follow each step (S) in the explanatory diagram of Figure 1.

[0013] [Step S11: Preparation Process] First, the coffee beans (green beans) are sorted and washed, and the roasting container and apparatus are prepared. The coffee beans may be soaked in water to allow them to absorb moisture. The container for the coffee beans needs to be a pressure-resistant, airtight container with a release valve that allows for pressurization, heating, and depressurization. Furthermore, it is preferable that the apparatus can heat and pressurize the container and is equipped with a pressure gauge and thermometer to display the pressure inside the container. It is also preferable that the container is constantly moving (rotating) so that the coffee beans can be agitated. This allows the beans to be roasted uniformly and prevents uneven roasting and burning. In this embodiment, a grain expansion processing device (a so-called puffed rice machine) is used as the apparatus for roasting the coffee beans. Since an existing grain expansion processing device can be used, there is no need to manufacture a new one, and pressurization, heating, and depressurization can be easily performed.

[0014] Generally, grain expansion processing equipment is used in confectionery making to expand grains (such as rice and wheat) by heating and pressurizing them, and rapidly changing the pressure to cause them to explode. The expansion of grains in grain expansion processing equipment is carried out as follows: First, heating the grains in the container causes the water contained in the grains to vaporize and expand, increasing the pressure inside the container. Next, opening the pressure release valve rapidly reduces the pressure inside the container. As the internal pressure of the grains remains high while the outside pressure is reduced, the grains expand due to this pressure difference.

[0015] On the other hand, coffee bean roasting involves slowly heating the beans to bring out their aroma and flavor, controlling the temperature to adjust the roast from light to dark. Therefore, grain expansion processing devices, which rapidly reduce pressure after heating and pressurizing to expand (explode) the beans, have not been used for coffee bean roasting. It was believed that using a grain expansion processing device on coffee beans would cause the beans to crack, break, or burn due to the sudden pressure change. After extensive research using a grain expansion processing device, the inventors have invented a roasting method that destroys only the internal structure of the coffee beans while maintaining their shape by opening a pressure release valve before the beans crack, break, or burn, and rapidly reducing the pressure inside the container. Note that any device that can seal, pressurize, and heat the coffee beans and rapidly reduce pressure may be used for roasting, not just a grain expansion processing device.

[0016] Also, as a device used after pressurizing and heating coffee beans and then rapidly decompressing them, prepare a roasting device (roaster) or a roasting utensil used in the step of heating the coffee beans without pressurizing. The heating methods of the roasting device include direct fire type, hot air type, electric type, etc., and any roasting device can be used. Also, the coffee beans may be roasted using utensils such as a frying pan without using a roasting device. However, using a roasting device can heat the coffee beans more stably and uniformly, so they can be finished deliciously and fragrant. In this embodiment, an existing roasting device is used. After preparing the coffee beans and the device, proceed to the heating and pressurizing steps.

[0017] [Step S12: Heating and Pressurizing Step (0 to 120°C)] This step is the process of evaporating the moisture contained in the coffee beans and the moisture on the surface. First, put the coffee beans in a container and heat them. In this embodiment, put the coffee beans in the pressure-resistant container of the aforementioned grain expansion processing device, seal it, and heat it while rotating the container. In the heating step at a temperature of 0 to 120°C, the moisture on the surface of the coffee beans begins to evaporate, and the moisture inside the coffee beans gradually escapes. As the moisture content of the coffee beans decreases, the internal structure of the coffee beans gradually changes. In some cases, a slight chemical change may start. Also, due to the expansion of the surrounding air and the evaporation of moisture from the coffee beans, the pressure in the water vapor atmosphere inside the container gradually increases.

[0018] The pressure (gauge pressure) in the water vapor atmosphere inside the container of the grain expansion processing device can be calculated based on the "Steam Table" edited by the Japan Society of Mechanical Engineers. The pressure in the water vapor atmosphere inside the container from 0°C to 100°C is 0 kPaG, and it gradually increases when it exceeds 100°C, and it is about 100 kPaG at 120°C. It can be seen from Figure 2 that the pressure inside the container gradually increases as the temperature rises above 100°C.

[0019] [Step S13: Heating and Pressurizing Step (120°C to 180°C)] When the container of the grain expansion processing apparatus is further heated and the temperature exceeds 120°C, the pressure in the steam atmosphere inside the container exceeds 100 kPaG, and the chemical reaction (Maillard reaction) of the coffee beans begins. The Maillard reaction is a non-enzymatic reaction between reducing sugars and amino compounds (mainly amino acids and peptides), and plays a central role in flavor formation during the coffee bean roasting process. This roasting process creates the taste and aroma.

[0020] Above 160°C, the Maillard reaction accelerates further, forming key flavor elements such as aroma and body. The pressure in a steam atmosphere at 160°C is approximately 520 kPaG, and the pressure in a steam atmosphere at 180°C is approximately 1000 kPaG (1 MPaG) (see Figure 2). Generally, when the pressure inside the container of a grain expansion processing device reaches about 1 MPaG, the pressure inside the container is released, reducing the pressure and causing the grain to expand. Roasting coffee beans requires heating to about 230°C, but if heated to 230°C without intervention, the pressure inside the container becomes a dangerously high 2.7 MPaG. Furthermore, it is expected that the coffee beans will be destroyed by the high pressure. In this embodiment, heating is stopped at a predetermined temperature T1 (175~185°C) where the pressure inside the container (a predetermined pressure) is approximately 1 MPaG. Note that the predetermined pressure and temperature T1 are not limited to the values ​​in this embodiment and can be appropriately changed depending on the type of coffee beans and equipment used.

[0021] [Step S14: Rapid depressurization process] After the pressure inside the container of the grain expansion processing device reaches 1 MPaG, the pressure release valve of the container is opened, and the pressure inside the container is rapidly reduced to atmospheric pressure (see Figure 2). By rapidly reducing the pressure, the internal pressure of the coffee beans remains high while the outside is under reduced pressure, causing the internal microstructure of the coffee beans to burst and break due to the pressure difference. Because coffee beans have a hard surface, they hardly expand (puff) like grains (rice, wheat), and the shape of the coffee beans does not change much. However, due to the rapid pressure difference, only the internal tissue of the coffee beans is physically damaged, creating microscopic holes. In this embodiment, a grain expansion processing device was used in steps S12 to S14, but as mentioned above, other devices may be used.

[0022] [Step S15: Heating Process (~230°C)] In this process, normal roasting is performed without applying pressure. The coffee beans taken out from the grain expansion processing device by rapidly reducing the pressure are put into a roasting device and further heated. By this process, the aroma and flavor of the coffee beans can be adjusted. As described above, instead of using a roasting device, a frying pan or the like may be used. Generally, in a roasting device, the container rotates so as to roast the coffee beans uniformly, and the temperature inside the container is measured and displayed. Also, it is preferable to use a roasting device equipped with a cooling function (exhaust fan) for rapidly cooling the roasted coffee beans. The coffee beans are put into the roasting device and heated until a predetermined temperature T2 (T1 < T2) is reached. In this embodiment, the predetermined temperature T2 is 220 - 230°C, and preferably heated up to 230°C. By heating the coffee beans up to 230°C, due to the rupture of the internal structure of the coffee beans, the thermal decomposition reaction proceeds. This process is a process for creating the taste of the coffee beans, and the sweetness, bitterness, acidity, etc. are finally adjusted. Note that heating above 230°C will cause the coffee beans to burn, making it difficult to adjust the sweetness, bitterness, acidity, etc., so the heating is limited to 230°C. The predetermined temperature T2 is not limited to the numerical values of this embodiment as long as it satisfies the relationship T1 < T2, and can be appropriately changed depending on the type of coffee beans used and the device.

[0023] [Step S16: Cooling Process] After heating and roasting the coffee beans up to 230°C, it is necessary to rapidly cool them immediately to stop the progress of roasting. Thereby, the aroma of the coffee beans can be locked in and the flavor can be preserved for a long time. As described above, when the roasting device has a cooling function (exhaust fan), it can be easily cooled using that function. When roasting using a roasting machine or a frying pan without a cooling function, for example, the coffee beans can be lifted into a colander and cooled by blowing air with a hand-held fan or a blower.

[0024] After cooling the roasted coffee beans, by properly storing them, the flavor of the coffee beans can be enjoyed for a long time. In the above manner, the roasting of the coffee beans in this embodiment is completed.

[0025] As explained above, the coffee bean roasting method of this embodiment can destroy the internal structure of the coffee beans by rapidly reducing the pressure to atmospheric pressure. This increases the number of microscopic pores in the coffee beans, making it easier for hot water or water to penetrate into the inside of the beans. As a result, the aroma and flavor of the coffee can be enhanced compared to conventional methods. Furthermore, the coffee bean roasting method of this embodiment does not require the manufacture of any special equipment and can be carried out using existing equipment. Coffee beans roasted using this embodiment can be sold as coffee beans or coffee grounds with high aroma and flavor and high extraction efficiency.

[0026] The coffee bean roasting method described above is merely an example and does not limit the scope of the invention. It can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. [Industrial applicability]

[0027] The present invention's technique for disrupting the internal tissue structure through pressure changes is applicable to other grains and legumes. This makes it possible to create new textures and flavors in other grains and legumes, and to provide new methods for extracting components.

Claims

[Claim 1] A roasting method for roasting coffee beans using a grain expansion processing device, The process involves placing the coffee beans into the grain expansion processing apparatus and heating and pressurizing them while rotating the container, The process involves first creating a steam atmosphere inside the grain expansion processing apparatus with a temperature of 175 to 185°C and a pressure of approximately 1 MPaG, and then rapidly reducing the pressure to atmospheric pressure. The process includes removing the coffee beans from the grain expansion processing apparatus and continuing the roasting process without pressurizing them, heating them to a temperature of 220-230°C. A method for roasting coffee beans, characterized by roasting the beans while maintaining their external shape and destroying only the internal tissue.

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