Color monitoring device for roasted products, roasting device, and method for roasting roasted products

Abstract

A color monitoring device for a roasted product (14) comprising a light transmitter (18) for illuminating the roasted product (14), optical means (52) for directing a reflected light beam onto a light guide arrangement (24) and an evaluation unit (36), the light guide arrangement (24) being connected to the evaluation unit (36) by a control technique for defining a color value of the roasted product (14), which can be determined as a quotient of a reflected measurement value of a light intensity L1 of an incident light to a light intensity L2 of a reflected light at at least two light wavelengths λ1, λ2, a measuring probe (26) is provided with a light guide arrangement (24) guided at a first end (48) of the measuring probe (26) to a first opening (46), the light guide arrangement (24) feeding a first light guide (40) to a light receiver (34) and a second light guide (42) to a light transmitter (18) for directing the reflected light, the second opening (54) being provided with optical means for applying a light beam emitted by a light source (20, 22).

Description

[Technical field]

[0001] The invention relates to a color monitoring device for roasted products, comprising a light transmitter with at least one light source for illuminating the roasted product, optical means for applying a reflected light beam to a light guide device, and an evaluation unit, the light guide device being connected by a control technique to an evaluation unit for defining at least one color value for the roasted product, which can be determined by forming a quotient of at least two light wavelengths λ1, λ2 of a respective reflection measurement, the light intensity of the incident light, the light intensity of the reflected light.The invention also relates to a roasting device and a method for roasting a roasted product. [Background technology]

[0002] A general color monitoring device for roasted products of plant-derived materials such as coffee beans, cereals, cocoa, etc. is known from German Publication No. 37 20 388 A1. This publication discloses an arrangement and a method in which the control variables, the roasting temperature and the roasting time, are checked or adjusted on the basis of the determined color value of the roasted product. For this purpose, the difference between the light intensity L1 of the incident light and the corresponding light intensity L2 of the reflected light for at least two light wavelengths λ1, λ2 (reflection measurements) is calculated. The formation of the quotient of the two reflection measurements of the respective wavelengths eliminates errors that may occur during the measurement of the reflected light beam due to special basic conditions. However, such an arrangement or such a method for monitoring the color of a moving roasted product could not be established on the market, since the color monitoring device is too complex in construction and the light supply to both the roasting vessel and the light guide is error-prone and inaccurate, for example due to the hot and dusty atmosphere in the roasting vessel. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, the object of the present invention is to avoid the above mentioned drawbacks in a simple and cost-effective manner. [Means for solving the problem]

[0004] According to the invention, this object is solved by providing a measurement probe comprising a light guide device guided into the measurement probe at a first opening at a first end, the light guide device comprising a light guide for applying the light emitted by the light transmitter and a second light guide for applying the reflected light to the light receiver, optical means being provided for applying the reflected light beam to the second end of the measurement probe. The measurement probe can here be configured in a simple manner as an elongated component with a first end opposite the second end. By integrating the light inputs of both the emitted and the reflected light beam in the measurement probe, a particularly simple and compact color monitoring device for determining color values ​​is made possible. In particular, such a measurement probe is particularly suitable for reaching the roasting vessel. It should be noted here that the term color value also includes comparative values ​​of known color experimental devices determined by mathematical models.

[0005] In the most advantageous embodiment, the optical means for directing the reflected light beam is configured as a collecting lens.

[0006] In a particularly advantageous manner, the light guide arrangement is configured as a Y-shaped light guide, a first light guide is connected to the light transmitter and a second light guide is connected to the light receiver, and the single light guide is guided into the measuring probe through the first opening.

[0007] A color monitoring device that is particularly easy to manufacture and whose light transmitter does not require special cooling is made possible by the fact that the light sensor contains at least one LED or at least one laser as a light source, which makes it possible in a simple way to generate very precisely the desired wavelength of the emitted light.

[0008] It has been found that the optical wavelength λ1=960-970 nm and the optical wavelength λ2=1550 nm are a particularly advantageous optical wavelength pair.

[0009] In order to keep the second opening, and thus also the optical means provided in this area, free of water vapor or dirt particles, the measuring probe comprises a wash air connection for connection to a wash air armature and an air guide arrangement in the area of ​​the optical means, which surrounds both the side of the optical means directed towards the inside and the side of the optical means directed into the roasting vessel with scavenging air, thus making it possible in a particularly simple way to keep the probe in ideal conditions when installed directly in the roasting vessel or to cool it.

[0010] In a particularly advantageous embodiment, the optical transmitter comprises a light source or filter means for generating light of different optical wavelengths, and the optical receiver comprises means for processing light of different optical wavelengths. In this case, it is particularly advantageous if the light sources for generating light with different optical wavelengths are differently designed LEDs or lasers. In this case, it is particularly advantageous if the optical transmitter is connected to the optical receiver by a control technique for transmitting the respective emitted optical wavelength to the optical receiver, in this way a reliable process for the formation of the quotient is guaranteed.

[0011] In a particularly advantageous embodiment, the measuring probe is provided with a removable cap having a second opening at the end directed towards the roasting vessel so that the measuring probe can be maintained and cleaned in a simple manner without the need to remove the single light guide.

[0012] The object is also solved by a roasting apparatus comprising a roasting vessel defining a roasting chamber, wherein a roaster control unit of the roasting apparatus is connected by control technology to an evaluation unit of said color monitoring device, and wherein a measuring probe is arranged on the roasting vessel such that a second end of the measuring probe extends into the roasting chamber.

[0013] In a particularly advantageous manner, the color values ​​determined in the evaluation unit can be used as control variables for a roast machine control unit to determine the degree of roast. In this case, the color values ​​can also comprise comparison values ​​from known color laboratory devices such as Colorlet 4, Agtron, etc., in order to be connected in a simple manner to existing roast machine control units.

[0014] Usually the roasting chamber is provided with a temperature sensor and a maximum temperature value Tmax for stopping the roasting process is stored in the roaster control unit.

[0015] This object is also solved by a method for roasting a roasted product in a roasting vessel of such a roasting apparatus, in which the roasting process is terminated as soon as the determined color value corresponds to a desired color value stored in the roaster control unit. In an advantageous manner, a maximum temperature value Tmax is additionally stored, upon reaching which the roasting process is terminated.

[0016] In order to prevent the optical means of the measuring probe from being covered with water vapor at the end of the roasting process, it is advantageous to increase the cleaning air pressure beforehand at the end of the roasting process. Increasing the pressure of the cleaning air up to 6 bar has already proven to be advantageous.

[0017] In particular, it is advantageous if the mathematical model converts the color values ​​into comparison values ​​for a color laboratory device, e.g. Colorlet 4, Agtron, etc., for communication with existing roast machine control units.

[0018] The invention will now be explained in more detail with reference to the drawings. [Brief description of the drawings]

[0019] [Figure 1] 1A-1D are schematic diagrams of different roasting machines equipped with a color monitoring device; [Diagram 2] FIG. 1 shows a detailed view of a measuring probe placed on a roasting vessel. [Diagram 3] FIG. 3 is a detailed view of the measurement probe of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Figure 1 shows a schematic diagram of a roasting apparatus 2 according to the invention. The roasting apparatus 2 essentially comprises a roaster 4, which in this embodiment is represented by three alternatively used roasting vessels 6, 8, 10, in order to show diagrammatically that the roasting apparatus 2 is not limited to one particular roaster 4. The roasting vessel 6 is a paddle wheel roaster, the roasting vessel 8 is a drum roaster and the roasting vessel 10 is a tray roaster. The roaster 4 is connected by control technology to a roaster control unit 12 which notably controls the roasting process. The roasted product 14 can be coffee beans, cocoa beans or material derived from plants such as cereals.

[0021] The roasting apparatus 2 also comprises a color monitoring device 16 according to the invention, which can also be adapted for each roasting vessel 6, 8, 10. In this case, the color monitoring device 16 comprises a light transmitter 18 with light sources 20, 22, which in this embodiment 2 are designed differently in terms of light wavelength as LEDs or lasers. The light transmitter 18 is connected to a measuring probe 26 via a light guide device 24, such that the roasted products 14 in the respective roasting vessel 6, 8, 10 are illuminated with light of the light wavelength λ1 of the light source 20 or with light of the light wavelength λ2 of the light source 22. For this purpose, the measuring probe 26 (as shown in more detail in Fig. 2) is attached to the respective roasting vessel 6, 8, 10 and extends into the respective roasting chamber 28, 30, 32.

[0022] Furthermore, the color monitoring device 16 comprises a light receiver 34 and an evaluation unit 36. In this context, it is pointed out that this representation is merely schematic and in particular the light transmitter 18, the light receiver 34 and the evaluation unit 36 ​​can also be arranged in a housing. The light receiver 34 is also operatively connected to the light guide device 24 and receives the light of the light wavelengths λ1 and λ2 reflected by the roasted product 14 into the measuring probe 26. For this purpose, the light receiver 34 comprises in particular means 38 for processing the light of the different light wavelengths λ1 and λ2. To enable this in a particularly simple way, the light transmitter 18 is connected to the light receiver 34 by control technology.

[0023] The light guide device 24 is configured here as a Y-shaped light guide, with a first light guide 40 connected to the light transmitter 18 and a second light guide 42 connected to the light receiver 34. Both light guides 40, 42 are connected in a known manner to a single light guide 44, which is guided into the elongated measurement probe 26 through a first opening 46. The first opening 46 is provided at a first end 48 of the measurement probe. At an end 50 (see FIG. 3 ) opposite to the first end 48, the end of the single light guide 44 is provided with a collecting lens 52 as optical means for applying the emitted light beam to the respective roasting chambers 28, 30, 32 and the light beam reflected by the roasted product 14 to the single light guide 44 through a second opening 54. In this case, the collecting lens 52 is firmly connected to the single light guide 44, which is fixed in a defined manner in the measurement probe 26 via a mounting device 55.

[0024] Furthermore, the measuring probe 26 comprises a cleaning air connection 56 connected to a cleaning air armature 58. Hereby, cleaning air is fed under pressure into the measuring probe 26 in order to keep the side of the collecting lens 52 facing the second opening 54 free from dirt and fogging. As shown in FIG. 3, the single light guide 44 with the collecting lens 52 is provided in an air guiding device 60 in such a way that when the cleaning air leaves the measuring probe via the second opening 54, it flows around the collecting lens 52 on the side facing the second opening 54 and also leaves the measuring probe 26 via this side. In this case, the air guiding device 60 essentially consists of a channel surrounding the light guide 44. At the same time, the roasting supply air or the roasting exhaust air cannot enter the roasting vessel 6, 8, 10, whereby a proper cooling of the system is achieved by overpressurization of the cleaning air. To ensure easy maintenance and cleaning, the measuring probe 26 comprises a removable cap 62 with the second opening 54 at the end 50 facing the roasting vessel 6, 8, 10.

[0025] In the method for roasting a roasted product in a roasting device 2 with one of three roasting vessels 6, 8, 10, the roasting process is monitored via so-called color values ​​stored in the roaster control unit 12 of said roasted product 14. For this purpose, light with light wavelengths λ1 and λ2 is transmitted alternately by the light transmitter via the light guide device 24 and the collecting lens 52 onto the roasted product to be roasted in the respective roasting chamber 28, 30, 32. The light reflected by the roasted product is guided via the light guide device to the light receiver 34 and transmitted to an assigned evaluation unit 36 ​​by a signal coming from the light transmitter 18. Here, the formation of a quotient of the respective reflection measurements of the incident light and the reflected light at the respective light wavelengths λ1, λ2 is carried out. The color value can then be determined from the formation of the quotient of the reflection measurements of the two light wavelengths λ1, λ2. When the color value stored in the roaster control unit is reached, the roasting process is terminated.

[0026] In addition, a roast end temperature Tmax is stored in the roaster control unit 12, the purpose of which is to prevent the roaster 2 from overheating in case of an inaccurate measurement by the measuring probe 26. When this temperature Tmax is reached, the roast process is also ended, i.e. this temperature limit Tmax essentially serves as a safety feature to prevent over-roasting.

Claims

1. A color monitoring device for a roasted product (14), comprising: an optical transmitter (18) having at least one light source (20, 22) for illuminating the roasted product (14); optical means (52) for applying the reflected light beam to the light guide device (24); an evaluation unit (36), the light guide device (24) is controllably connected to the evaluation unit (36) for defining at least one color value for the roasted product (14), the color value being determinable by taking a quotient of reflectance measurements of the light intensity L1 of incident light to the light intensity L2 of reflected light for at least two light wavelengths λ1, λ2; a measuring probe (26) is provided with the light guide device (24) directed at a first end (48) to a first opening (46), the light guide device (24) comprising a first light guide (40) for transmitting light emitted by a light transmitter (18) and a second light guide (42) for transmitting reflected light to a light receiver (34); optical means (52) for applying a radiated light beam emitted by a light source (20, 22) and a light beam reflected by the roasted product (14) are provided at a second opening (54) at a second end (50) of the measuring probe (26); 13. A color monitoring device, characterized in that the measuring probe (26) comprises, in the region of the optical means (52), a cleaning air connection (56) for connection to a cleaning air armature (58) and to an air guiding device (60), is attached to the roasting vessel (6, 8, 10) and extends into the roasting chamber (28, 30, 32).

2. 2. A color monitoring device according to claim 1, characterized in that the optical means (52) for applying the emitted light beam and the reflected light beam are configured as focusing lenses.

3. 3. A color monitoring device according to claim 1 or 2, characterized in that the light guide arrangement (24) is configured as a Y-shaped light guide, the first light guide (40) being connected to the light transmitter (18), the second light guide (42) being connected to the light receiver (34), and a single light guide (44) being led to the measurement probe (26) through the first opening (46).

4. 3. A color monitoring device according to claim 1 or 2, characterized in that the optical transmitter (18) comprises at least one LED (20, 22) or at least one laser as a light source.

5. 3. A color monitoring device according to claim 1, wherein the optical wavelength .lambda.1 is 960 to 970 nm, and the optical wavelength .lambda.2 is 1550 nm.

6. 3. A color monitoring device according to claim 1 or 2, characterized in that the optical transmitter (18) comprises light sources (20, 22) or filter means for generating light having different optical wavelengths λ1, λ2, and the optical receiver (34) comprises means (38) for processing light of the different optical wavelengths λ1, λ2.

7. 7. A color monitoring device according to claim 6, characterized in that the light sources (20, 22) for generating light with different light wavelengths .lambda.1, .lambda.2 are differently configured LEDs or lasers.

8. 7. A color monitoring device as claimed in claim 6, characterized in that the optical transmitter (18) is connected to the optical receiver (34) by control technology to transmit the respective optical wavelengths emitted to the optical receiver (34).

9. 3. A color monitoring device according to claim 1 or 2, characterized in that the measuring probe (26) is provided with a removable cap (62) on the second opening (54) of the end (50) directed towards the roasting vessel (6, 8, 10).

10. A roasting apparatus having a roasting machine (4) including a roasting vessel (6, 8, 10) defining the roasting chamber (28, 30, 32), wherein a roasting machine control unit (12) of the roasting machine (4) is connected by control technology to the evaluation unit (36) of a color monitoring device (16) as described in claim 1 or 2, and wherein the measuring probe (26) is positioned on the roasting vessel (6, 8, 10) such that a second end of the measuring probe (26) extends into the roasting chamber (28, 30, 32).

11. 11. Roast apparatus according to claim 10, characterized in that the color value determined in the evaluation unit (36) can be used as a control variable for the roast machine control unit (12) to determine the degree of roast.

12. 11. Roasting device according to claim 10, characterised in that the roasting chambers (28, 30, 32) are provided with temperature sensors and a maximum temperature value Tmax is stored in the roaster control unit (12) in order to interrupt the roasting process.

13. 13. A method for roasting the roasted products (14) in the roasting vessel (6, 8, 10) of a roasting device (2) according to claim 12, wherein the roasting process is terminated as soon as the determined color value corresponds to the desired color value stored in the roaster control unit (12).

14. 14. Method for roasting a roasted product (14), as claimed in claim 13, characterized in that a maximum temperature value Tmax is stored and, when this value is reached, the roasting process is terminated.

15. 14. A method for roasting a roasted product as claimed in claim 13, characterized in that the cleaning air supply is increased at the end of the roasting process.

16. 14. A method for roasting a roasted product as claimed in claim 13, characterized in that the colour values ​​are converted by a mathematical model into comparative values ​​of a colour laboratory device, e.g. Colourlet 4, Agtron etc.

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