GRINDING COFFEE BEANS

Description

[0001] The invention relates to a device for processing roasted coffee beans with a unit for grinding the beans and to a method for processing coffee beans, wherein the coffee beans are ground and the temperature of the ground material, at least at the start of the grinding process, is between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C.

[0002] In the conventional processing process for producing ground and packaged coffee, green coffee is first roasted at temperatures above 150°C and then cooled using room air, which typically results in a bean temperature of approximately 5°C above room temperature, i.e. a bean temperature between 20 - 40°C.

[0003] The coffee is then ground, with the grinding tools, such as the rollers, being cooled to largely prevent the ground coffee from rising in temperature. The final temperature of the ground coffee is therefore in the range of 20–40°C.

[0004] During the final part of the roasting process, pyrolytic reactions occur, releasing water and CO2. Because the cell structure of the coffee bean is rather thick-walled, the CO2 cannot evaporate during the process, resulting in a CO2-induced overpressure in the cells at the end of the roasting process, which can reach up to several bar.

[0005] During the subsequent grinding process, the cells are opened up depending on the degree of grinding, although a portion of undamaged cells usually remains. If the ground coffee is packaged immediately after grinding, degassing continues, which can lead to warping or even bursting of the packaging. For this reason, the coffee is temporarily stored before packaging to ensure sufficient degassing. In conventional processing, the coffee is stored in silos until the CO2 is completely released and then packaged.

[0006] Space and time must therefore be allowed during the processing.

[0007] In addition, open intermediate storage also causes flavors and aromas to escape and can lead to oxidation of the coffee, which may impair the quality and shelf life of the coffee.

[0008] There is therefore a need to shorten the intermediate storage period. This can be achieved, for example, by equipping the ground coffee packaging with a one-way valve, as disclosed in EP1363401, which allows CO2 degassing but prevents oxygen penetration. However, these valves are generally only suitable for larger containers. Alternatively, it is known, for example, from Bezman et al. "Method for Continuous Monitoring Rates of CO2 Release from R&G Coffee" (22nd International Conference on Coffee Science, Campinas Colloquium, 2008), that degassing is accelerated at higher storage temperatures. However, this approach requires additional equipment and energy expenditure during intermediate storage.

[0009] Such devices are also known from GB176305 and US2002110626.

[0010] The object is therefore to avoid the disadvantages of the known method and to provide a device and a method for processing coffee by which degassing of ground coffee in the packaging can be prevented as far as possible and which does not unnecessarily prolong and / or increase the cost of the processing.

[0011] The object is achieved by a device for processing roasted coffee beans, wherein the device comprises a thermal unit which ensures that the temperature of the roasted coffee beans during the grinding process, at least at the start of the grinding process, is between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C, wherein the grinding takes place in particular in a roller mill with one, two or more passages.

[0012] A passage typically consists of a pair of rollers. Successive passages can be created by adding individual rollers. Preferably, each passage consists of a separate pair of rollers.

[0013] A roller mill can process smaller batches of ground material in a batch operation, but larger quantities of ground material are preferably processed quasi-continuously, with the ground material being fed to the selection mechanism via a feed device and removed from the mill via a discharge device. In continuous or quasi-continuous processing, the entire ground material is essentially passed over the same pair of rollers only once during the grinding process, allowing for a continuous supply of ground material.

[0014] The device according to the invention comprises a modular rolling mill which can be optionally equipped with one or more rolling passages.

[0015] Surprisingly, it has been found that it is advantageous not to cool the roasted coffee beans to excessively low temperatures in preparation for the subsequent grinding process, or during the grinding process, as is usually done, but to transfer them to the grinding unit while still warm and / or to process them therein. To ensure this process runs in a controlled manner, the device according to the invention contains a thermal unit. The thermal unit ensures that the coffee is transferred to the grinding unit, in particular the roller mill, at the desired temperatures and / or is ground at the desired temperatures and prevents the coffee from being processed at temperatures that are too cold or too hot. For this purpose, the cooling process after roasting can be interrupted in a controlled manner, or active heating can take place.

[0016] Hot grinding promotes degassing during the grinding process, and eliminates the need for subsequent heating of the ground coffee to a higher temperature during storage. This accelerates degassing, shortens the coffee's lifespan, and generally eliminates the need for additional energy input after grinding.

[0017] To counteract unwanted aroma release, the thermal unit can be coupled with an aroma protection or aroma recovery system, for example an adsorption system.

[0018] According to the invention, the thermal unit influences the temperature of the roasted coffee before grinding. For this purpose, the thermal unit comprises a temperature control device and a ground feed device, in particular a ground feed device in a rolling mill, wherein the temperature control device and ground feed device are designed such that the roasted coffee beans can be tempered to ground material temperatures of 30°C and 150°C for the start of the grinding process and can be ground at these temperatures.

[0019] Preferably, the tempering device is a cooling device in which the roasted coffee beans are cooled immediately after roasting to a temperature between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C. By means of the grinding feed device, the coffee beans are transferred at this temperature to the grinding unit.

[0020] Alternatively, the tempering device can be a device for heating roasted, already cooled coffee to a temperature between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C.

[0021] In the device according to the invention, the thermal unit influences the temperature of the roasted coffee during grinding. For this purpose, the thermal unit comprises a temperature control device for the grinding unit, in particular for a roller mill, which is designed to maintain the temperature of the ground coffee between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, and particularly preferably between 40°C and 60°C.

[0022] It may be sufficient if the ground material has the desired temperature at the beginning of the grinding process, but preferably the temperature of the ground material is influenced throughout the entire grinding process.

[0023] The temperature control system for the grinding unit can bring the entire grinding unit to the target temperature or within the target temperature range, or just the grinding tools. In particular, one or more passages of the rolling mill are appropriately temperature-controlled.

[0024] The temperature control device for the grinding unit is a temperature control device for grinding tools, for example, the grinding rollers. The temperature control device maintains the grinding tools during the grinding process in at least one grinding stage at a temperature or a temperature range between 30°C and 150°C, in particular between 35°C and 120°C, more particularly between 40°C and 110°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C or between 60°C and 80°C.

[0025] Advantageously, the respective temperatures of separate roller passages or individual rollers can be controlled individually, i.e. independently of each other. This allows a temperature profile to be created along the grinding path.

[0026] Grinding tools, such as grinding rollers, are often interspersed with channels through which cooling water can be passed. These channels can be used to introduce a tempering fluid into the grinding tools. The temperature of the tempering fluid, such as water or oil, can be controlled and / or regulated to bring the tools to the desired target temperature or temperature range.

[0027] The temperature control unit preferably includes a temperature sensor located in the roller to regulate the temperature of the tempering fluid. The temperature of the tempering fluid in the rollers is a good measure of the roller temperature.

[0028] The temperature control of the grinding tools can also be carried out thermoelectrically, for example via a Peltier element

[0029] Advantageously, the temperature of the ground material can be adjusted via the thermal unit. For this purpose, the cooling and / or tempering device preferably comprises an input means for entering the target temperature or the target temperature range of the ground material, in this case the roasted coffee beans. The input means can be, for example, a switch, a slider, a rotary knob, and / or a keyboard. The input means can be provided with an indicator, for example a display, which shows the selectable temperatures, the selected temperature, and / or the selected temperature range. The thermal unit can also be connected to a processor system, via which the temperature or the temperature range is entered into the thermal unit directly or depending on other parameters.

[0030] In order to ensure that the ground coffee has the desired target temperature, or a temperature within the desired target temperature range, the device preferably comprises a measuring device for measuring the temperature of the roasted coffee before, during and / or after grinding.

[0031] The temperature of the ground material is preferably measured by measuring the temperature of the surrounding air or by measuring the bulk material in a bulk solid. For temperature measurement, the sensor can be placed in direct contact with the bulk material or the surrounding air, or the temperature can be measured contactlessly, for example, optically.

[0032] The device according to the invention preferably comprises a control device for controlling the temperature of the bean grinding unit, in particular the grinding tools, depending on the temperature of the ground material. The temperature of the grinding unit is then controlled automatically depending on the temperature of the ground material and the selected target temperature or the selected target temperature range. If the ground material leaving the grinding unit is too cold, the temperature is increased; if the ground material leaving the grinding unit is too warm, the temperature is decreased.

[0033] Advantageously, the device according to the invention comprises an input and comparison means with which the temperature of the ground material is determined as a function of the desired particle size distribution of the ground coffee.

[0034] It has been shown that finely ground coffee stores far less CO2 than coarsely ground coffee, so the degassing process generally needs to be forced less.

[0035] Energy consumption can therefore be optimized if the temperature of the ground coffee, which promotes degassing, is only adjusted to the extent necessary. Depending on the particle size distribution of the ground coffee, the temperature of the ground coffee can be precisely selected; generally, higher temperatures are preferred for coarser coffee and lower temperatures for finely ground coffee.

[0036] The control can be based on a table stored in a process system that establishes the relationship between particle size and degassing temperature. The data from the table can be collected empirically.

[0037] The control can also be based on online or inline measured data, for example on the basis of particle sizes after grinding, the CO2 content before and / or during and / or after grinding or on the basis of other parameters that are directly or indirectly relevant to the process.

[0038] The control can be based on expert knowledge or other artificial intelligent systems of control and / or regulation technology.

[0039] The object is further achieved by a method for processing coffee beans, in which it is ensured that the temperature of the ground material, at least at the start of the grinding process, in particular in a rolling mill with one or more passages, is between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C, wherein the grinding takes place in particular in a rolling mill with one, two or more passages.

[0040] A method according to the invention for processing coffee beans comprises, for example, the following process steps: (i) roasting the coffee beans; (ii) cooling the coffee beans to temperatures greater than 66°C; (iii) grinding the coffee beans at temperatures between 66°C and 150°C, in particular in a rolling mill with one or more passages.

[0041] Alternatively or additionally, the method according to the invention comprises the following method steps: (i) roasting the coffee beans; (ii) cooling the coffee beans; (iii) measuring the temperature of the coffee beans during cooling; (iv) if the temperature is greater than a predetermined target temperature, continue with (ii), otherwise transferring the coffee beans to a grinding unit; (v) grinding the coffee beans, in particular in a roller mill with one or more passes; wherein the target temperature has a value between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C.

[0042] The temperature measurement is performed continuously or at least at regular intervals. The typical time intervals between two consecutive temperature measurements are preferably 5-300 seconds. The measurement can also be performed quasi-continuously, e.g., in a control loop.

[0043] The object is further achieved by a method for processing coffee beans in a unit for grinding the beans, in particular as described above, in that the ground material is tempered before or during grinding in such a way that the temperature of the ground material is between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C, at least at the start of the grinding process.

[0044] For this purpose, the grinding unit, in particular a rolling mill, further in particular one or more rollers, is preferably tempered in such a way that the temperature of the material to be ground is between 30°C and 150°C, in particular between 35°C and 100°C, further in particular between 40°C and 60°C, in particular the grinding tools of at least one grinding stage are tempered to temperatures between 30°C and 150°C, in particular between 35°C and 120°C, further in particular between 40°C and 110°C, preferably between 40°C and 90°C, particularly preferably between 60°C and 80°C.

[0045] Since there is very close contact between the grinding tools and the material to be ground, a temperature equalization occurs between the material to be ground and the grinding tools and the material to be ground absorbs the heat emitted by the grinding tools.

[0046] For example, roasted coffee is heated by a roller with a temperature of 60°C to about 45°C.

[0047] Alternatively, a target temperature range can be selected which lies between 30°C and 150°C, in particular between 35°C and 100°C, more particularly between 40°C and 60°C, for example a temperature range with a temperature span of ±2-10°C.

[0048] The method according to the invention preferably comprises a process step in which the temperature of the roasted coffee is measured before, during, and / or after grinding. The measured temperature can be used for monitoring or to adjust the temperature selected, for example, in a temperature control unit.

[0049] Preferably, the temperature of the grinding unit, in particular of the grinding tools, is controlled and / or regulated depending on the temperature of the material to be ground.

[0050] The object is further achieved by a method, in particular as described above, in which the temperature of the ground material and / or the grinding unit, in particular the grinding tools, is adjusted depending on the desired particle size distribution of the ground coffee, in particular such that the CO 2 content of the ground coffee immediately after grinding, or after a storage time of a maximum of 20 hours, is below 0.5 ml / g.

[0051] For ground coffee with a maximum particle size distribution at approximately 500 µm, the ground coffee can, for example, be ground at a temperature of approximately 50°C so that after a degassing time of 7 hours after grinding, only a gas content of 0.5 ml / g remains.

[0052] If the coffee is to be ground more coarsely, i.e. if there are larger particles, it has proven advantageous to grind at a higher temperature; for finer ground coffee and smaller particles, grinding can take place at cooler temperatures.

[0053] The following table shows the relationship between particle size, given here as median of the particle sizes, and preferred temperature of the material to be ground. x50 [µm] Temperature [°C] 504 46 328 28 134 15

[0054] The invention is explained in more detail below with reference to drawings.

[0055] It shows Figure 1 shows a first example of a device according to the invention with a tempering device for the grinding tools in a schematic representation; Figure 2 shows a second example of a device according to the invention with a tempering device and a grinding feed device.

[0056] Figure 1 shows a schematic representation of a device 1 according to the invention with a thermal unit 2. In this case, the thermal unit 2 comprises a tempering device 3b for the grinding unit 4, here tempering devices 3b for the grinding tools 5, which here are pairs of rollers.

[0057] The device 1 comprises a measuring device 6 with a temperature sensor that detects the temperature of the ground coffee.

[0058] The measured temperature is used to adjust the temperature control devices 3b so that the ground material is kept at a specific target temperature.

[0059] Figure 2 shows a second example of a device according to the invention with a tempering device 3a and a grinding feed device 7.

[0060] The coffee is first roasted in a roasting machine 8, in this case a drum roaster. After roasting is complete, the coffee is fed into a temperature control device 3a, where air flows through the coffee, thereby cooling it. The temperature control device includes a measuring device 6 that monitors the coffee temperature. Once the coffee has reached the desired temperature for grinding, it is fed via the grinding feed device 7 into the grinder (not shown in this figure).

[0061] The grinding feed device 7 can be a bulk material valve that opens depending on a temperature, preferably a predetermined one. The valve can also receive a signal as soon as the measuring device 6 has detected a specific temperature value.

Claims

1. Device for processing roasted coffee beans, characterized in that the device comprises a thermal unit (2) that ensures that the temperature of the roasted coffee beans during the grinding process and at least at the start of the grinding process is between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, more preferably between 40°C and 60°C, the device comprising a modular roller mill that can be optionally equipped with one or more roller passages, and the thermal unit comprises a tempering device (3b) for the grinding unit, which is designed so that the temperature of the grinding material can be maintained between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C, wherein the tempering device for the milling unit is a tempering device for milling tools, wherein the tempering device maintains the milling tools during the milling process in at least one milling stage at a temperature or a temperature range between 30°C and 150°C, in particular between 35°C and 120°C, more particularly between 40°C and 110°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C or between 60°C and 80°C, the milling tools are permeated with channels through which a tempering liquid can be introduced into the milling tools, the temperature of the tempering liquid being controllable and / or adjustable in such a way that the tools are brought to the desired target temperature or the desired target temperature range, a tempering unit for controlling the temperature of tempering liquid introduced into channels of the milling tools preferably comprises a temperature sensor arranged in a roller, characterized in that the thermal unit comprises a tempering device (3a) and a grinding feed device (7) which are designed so that the roasted coffee beans can be tempered for the start of the grinding process to temperatures of the grinding material of 30°C and 150°C and can be ground at these temperatures.

2. The device according to claim 1, characterized in that the tempering device comprises an input means for entering the target temperature or the target temperature range of the grinding material or the thermal unit is connected to a processor system via which the temperature or temperature range is entered directly or in dependence on other parameters to the thermal unit.

3. The device according to one of the preceding claims, characterized in that it comprises a measuring device (6) for measuring the temperature of the roasted coffee before, during and / or after grinding.

4. The device according to one of the preceding claims, characterized in that the device comprises a control device for tempering the unit for grinding the beans, in particular for tempering the milling tools of at least one milling stage, as a function of the temperature of the grinding material.

5. The device according to one of the preceding claims, characterized in that the device has an input and comparison means with which the temperature of the grinding material is determined as a function of the desired particle size distribution of the outgoing grinding material.

6. A method for processing coffee beans in a roller mill for grinding the beans, wherein the temperature of the grinding material is controlled prior to the grinding operation such that the temperature of the grinding material is between 30°C and 150°C, at least at the start of the grinding operation, wherein the roller mill is temperature-controlled such that the temperature of the grinding material is between 30°C and 150°C.

7. The method according to claim 6, wherein the roller mill, in particular one or more rollers, is tempered in such a way that the temperature of the grinding material is between 30°C and 150°C, in particular between 35°C and 100°C, more particularly between 40°C and 60°C, in particular the milling tools of at least one milling stage are tempered to temperatures between 30°C and 150°C, in particular between 35°C and 120°C, more particularly between 40°C and 110°C, preferably between 40°C and 90°C, particularly preferably between 60°C and 80°C.

8. The method according to claim 6 or 7, wherein the temperature of the roasted coffee is measured before, during and / or after grinding.

9. A method for processing coffee beans comprising the steps of: (i) roasting the coffee beans; (ii) cooling the coffee beans to temperatures of greater than 66°C; (iii) grinding the coffee beans at temperatures between 66°C and 150°C in a single- or multi-pass roller mill.

10. The method according to claim 9, comprising the steps of - measuring the temperature of the coffee beans during cooling; - if the temperature is greater than a specified target temperature, continuing cooling, otherwise transferring the coffee beans to a grinding unit; - grinding the coffee beans, the target temperature having a value between 30°C and 150°C, in particular between 35°C and 100°C, preferably between 40°C and 90°C, particularly preferably between 40°C and 60°C.