PROCESS OF CALIBRATION OF A ROASTING APPARATUS

Abstract

The invention concerns process of calibration of a coffee beans roasting apparatus in order to reproduce coffee beans roasting recipes defined with one specific master roasting apparatus, said calibration process comprising the steps of: a—introducing at least one second temporary temperature probe inside the chamber of the roasting apparatus, b—controlling the heating device to reproduce a preset curve R said control being based on the temperature Treg regulated by the at least one first temperature probe, c—during the reproduction of the preset curve Rset, measuring the temperature Tcal in function of time inside the chamber, d—comparing the temperature Tcal@ti with the temperature Tref@ti of a pre-determined calibration curve Rref obtained with the master roasting apparatus (M), said calibration curve Rref representing the temperature Tref measured in the chamber of the specific master apparatus (M) while controlling the heating device of the master apparatus to reproduce said preset curve Rset, e—based on this comparison, calibrating the roasting apparatus by applying a correction, to the temperature Treg regulated by the first temperature probe inside the control system of the roasting apparatus.

Claims

1. Calibration process of a coffee beans roasting apparatus, in order to reproduce coffee beans roasting recipes defined with one specific master roasting apparatus, said coffee beans roasting apparatus comprising: a chamber to contain coffee beans, a heating device configured to supply hot air to the chamber, at least one first temperature probe to measure the temperature of air supplied by the heating device, said first temperature probe being positioned outside the chamber, a control system configured to control the heating device and configured to reproduce roasting curves, said roasting curves providing at least a set of points representing the temperature to be applied at discrete successive times ti, respectively, said control of the heating device implementing a feedback loop regulation based on the temperature Treg measured by the at least one first temperature probe, said calibration process comprising the steps of: a—introducing at least one second temporary temperature probe inside the chamber of the roasting apparatus to be calibrated or replacing said chamber by a temporary calibration chamber, said temporary calibration chamber comprising at least one second temperature probe, b—controlling the heating device to reproduce a preset curve Rset, said preset curve providing a series of points representing the temperature Tset@t1, Tset@t2, . . . Tset@tfinal to be applied at preset corresponding successive times t1, t2, . . . , tfinal respectively, said control being based on the temperature Treg measured by the at least one first temperature probe, c—during the reproduction of the preset curve Rset, measuring the temperature Tcal in function of time inside the chamber at the at least one second temperature probe enabling the determination of at least a set of points, d—comparing the temperature Tcal@ti measured at least one time ti with the temperature Tref@ti at said same time ti of a pre-determined reference curve Rref obtained with the master roasting apparatus, said reference curve Rref representing the temperature Tref measured in the chamber of the specific master apparatus while controlling the heating device of the master apparatus to reproduce said preset curve Rset, and e—based on this comparison, calibrating the roasting apparatus by applying a correction to the feedback loop regulation, preferably by applying a correction to the temperature Treg measured by the first temperature probe or by applying a correction to the temperatures T@ti provided by the roasting curves to be reproduced by the roasting apparatus.

2. Calibration process according to claim 1, wherein: step d) happens simultaneously to step c), and in step c), during the reproduction of the preset curve Rset, at predefined times tref corresponding temperatures Tref@tref i and Tcal@tref i are compared and a correction is immediately applied to the feedback loop regulation, preferably a correction is applied to the temperature Treg regulated by the first temperate probe or a correction is applied to the temperatures Tset@ti provided by the preset curve Rset, and in step e), based on the last correction in step c), the roasting apparatus is calibrated by applying said last correction to the feedback loop regulation, preferably by applying said last correction to the temperature Treg measured by the first temperature probe or by applying said last correction to the temperatures T@ti provided by the roasting curves to be reproduced by the roasting apparatus.

3. Calibration process according to claim 1, wherein between step c) and step d): the value of the temperature Tcal@ti measured at the at least one second temperature probe at step c) is adjusted to an adjusted value Tcal@ti-adjusted, said adjusted value depending on the second temperature probe introduced inside the chamber of the roasting apparatus to be calibrated or on the temporary calibration chamber replacing the chamber of the roasting apparatus to be calibrated, and in step d) this adjusted value Tcal@ti-adjusted is compared with the temperature Tref@ti.

4. Calibration process according to claim 1, wherein:
T.sub.cal@ti-adjusted=K.sub.2probe.Math.(T.sub.cal@ti).sup.2+K.sub.1probe.Math.T.sub.cal@ti+T.sub.probe wherein: Tprobe corresponds to a preset temperature offset, said preset temperature offset being specifically pre-determined for the at least one second temporary temperature probe introduced inside the chamber of the roasting apparatus to be calibrated or for the temporary calibration chamber replacing the chamber of the roasting apparatus to be calibrated, or is equal to 0 by default, K1probe and corresponds to a preset temperature ratio, said preset temperature ratio being specifically pre-determined for the at least one second temporary temperature probe introduced inside the chamber of the roasting apparatus to be calibrated or for the temporary calibration chamber replacing the chamber of the roasting apparatus to be calibrated, or is equal to 1 by default, and K2probe and corresponds to a preset temperature ratio, said preset temperature ratio being specifically pre-determined for the at least one second temporary temperature probe introduced inside the chamber of the roasting apparatus to be calibrated or for the temporary calibration chamber replacing the chamber of the roasting apparatus to be calibrated, or is equal to 0 by default.

5. Calibration process according to claim 4, wherein, in step c), during the reproduction of the preset curve Rset, the value of Tprobe and/or the value of K1probe and/or the value of K2probe varies with time and/or temperature.

6. Calibration process according to claim 1, wherein: step d) happens simultaneously to step c), and in step c), during the reproduction of the preset curve Rset, at predefined times tref i, the corresponding ratio Tref@tref i/Tcal@tref i is calculated and a correction is immediately applied: either to the temperatures Tset provided by the roasting curves to be reproduced, said correction being a multiplication factor Ki defined as follows: $K_i=K_0\underset{n=1}{\overset{i}{.Math.}}\frac{T_{\mathrm{ref}@\mathrm{tref}n}}{T_{c\mathrm{al}@\mathrm{tref}n}}$ wherein: K0 is preset, or is equal to 1 by default, or to the temperature Treg measured by the first temperature probe, said correction being a multiplication factor $\frac{1}{K},$ in step e), based on the last defined ratio Ki in step c), the roasting apparatus is calibrated by applying: said factor Ki of correction to the temperatures T@ti provided by the roasting curves to be reproduced by the roasting apparatus or said factor $\frac{1}{K},$  to the temperature Treg measured by the first temperature probe.

7. Calibration process according to claim 1, wherein, K0 corresponds to: a preset factor specifically pre-determined for a series of similar manufactured apparatuses, and a preset factor pre-determined for specific ambient conditions.

8. Calibration process according to claim 6, wherein, in step c), if for successive tref i the corresponding calculated ratios Tref@tref i/Tcal@tref i converge to one fixed value, then step c) is stopped and the last calculated factor of correction Ki is used as the last defined ratio in step d).

9. Calibration process according to claim 6, wherein, in step c), if for successive tref i the corresponding calculated ratios Tref@tref i/Tcal@tref i do not converge to one fixed value, then the calibration process is stopped.

10. Calibration process according to claim 1, wherein: the preset curve Rset is a curve established with the master roasting apparatus for the roasting of beans of a specific type of coffee beans and a specific quantity of said coffee beans, and before step b), coffee beans of said specific type and said specific quantity are introduced inside the chamber of the roasting apparatus or in the temporary calibration chamber, and in step b), the heating device is controlled to reproduce said preset curve Rset while the chamber of the roasting apparatus comprises said coffee beans.

11. Calibration process according to claim 1, wherein: the preset curve Rset is a curve established with the master roasting apparatus for the roasting of beans of coffee of specific type of coffee beans and a specific quantity of said coffee beans, before step b), coffee beans of said specific type and said specific quantity are introduced inside the chamber of the roasting apparatus or in the temporary calibration chamber, in step b), the heating device is controlled to reproduce said preset curve Rset while the chamber of the roasting apparatus comprises said coffee beans, and in step d), the temperature Tcal@ti is compared with the temperature Tref@ti and the ratio Kfinal=Tref@tfinal/Tcal@tfinal is calculated at the final time tfinal of the curves Rref and Rcal, in step e), a factor of correction corresponding to said calculated ratio is applied: either to the temperatures Tset provided by the roasting curves to be reproduced, said correction being a multiplication factor Kfinal or to the temperature Treg measured by the first temperature probe said correction being a multiplication factor $\frac{1}{\mathrm{Kfinal}}$

12. Calibration process according to claim 1, wherein: the preset curve Rset is a curve established with the master roasting apparatus for the roasting of granular inert objects, said granular inert objects being designed to simulate coffee beans, and before step b), said granular inert objects are introduced inside the chamber of the roasting apparatus or in the temporary calibration chamber, and in step b), the heating device is controlled to reproduce said preset curve Rset while the chamber of the roasting apparatus comprises said granular inert objects.

13. Calibration process according to claim 1, wherein: the preset curve Rset is a curve established with the chamber of the master roasting apparatus void of beans, and in step b), the heating device is controlled to reproduce said preset curve Rset while the chamber of the roasting apparatus is void of beans.

14. Calibration process according to claim 1, wherein the preset curve Rset, providing set of points comprises successively: in a first phase, a plateau of the temperature Tset at a fixed temperature Tset-stab, preferably of about 40° C., then in a second phase, an increase of temperature Tset from Tset-stab to a higher temperature Tset-high, and then in a third phase, a plateau of the temperature Tset at said temperature Tset-high.

15. Calibration process according to claim 1, wherein after step c) where the preset curve Rset, is reproduced, the roasting apparatus is cooled down to a temperature of about 40° C.

16. Calibration process according to claim 1, wherein: the coffee beans roasting apparatus comprising: a chamber to contain coffee beans, a heating device configured to supply hot air to the chamber, at least one first temperature probe to measure the temperature of air supplied by the heating device, said first temperature probe being positioned outside the chamber, a control system configured to control the heating device and configured to reproduce roasting curves, said roasting curves providing at least a set of points representing the temperature to be applied at discrete successive times ti, respectively, said control of the heating device implementing a feedback loop regulation based on the temperature Treg measured by the at least one first temperature probe, said calibration process comprising the steps of: a—introducing at least one second temporary temperature probe inside the chamber of the roasting apparatus to be calibrated or replacing said chamber by a temporary calibration chamber, said temporary calibration chamber comprising at least one second temperature probe, b—controlling the heating device to reproduce a preset curve Rset, said preset curve providing a series of points representing the temperature Tset@t1, Tset@t2, . . . Tset@tfinal to be applied at preset corresponding successive times t1, t2, . . . , tfinal respectively, said control being based on the temperature Treg measured by the at least one first temperature probe, c—during the reproduction of the preset curve Rset, measuring the temperature Tcal in function of time inside the chamber at the at least one second temperature probe enabling the determination of at least a set of points, d—comparing the temperature Tcal@ti measured at least one time ti with the temperature Tref@ti at said same time ti of a pre-determined reference curve Rref obtained with the master roasting apparatus, said reference curve Rref representing the temperature Tref measured in the chamber of the specific master apparatus while controlling the heating device of the master apparatus to reproduce said preset curve Rset, and e—based on this comparison, calibrating the roasting apparatus by applying a correction to the feedback loop regulation, preferably by applying a correction to the temperature Treg measured by the first temperature probe or by applying a correction to the temperatures T@ti provided by the roasting curves to be reproduced by the roasting apparatus.

17. Coffee beans roasting apparatus comprising: a chamber to contain coffee beans, a heating device to heat air supplied to the chamber, at least one first temperature probe to regulate the temperature supplied by the heating device, said first temperature probe being positioned outside the chamber, a control system configured to control the heating device and configured to reproduce roasting curves, said roasting curves providing at least a set of points representing the temperature to be applied at discrete successive times ti, respectively, said control of the heating device implementing a feedback loop regulation based on the temperature Treg measured by the at least one first temperature probe, wherein said apparatus comprises means to introduce temporary at least one second temperature probe inside the chamber of the roasting apparatus or is configured to enable the temporary replacement of the chamber by a calibration chamber, said calibration chamber comprising at least one second temperature probe, and wherein the control system is configured to receive input of measured temperature by said second temperature probe.

18-19. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0216] Specific embodiments of the invention are now described further, by way of example, with reference to the following drawings in which:

[0217] FIG. 1 is a schematic view of a roasting apparatus wherein the method of the present invention can be implemented,

[0218] FIG. 2A shows a block diagram of a control system of the apparatus according to FIG. 1,

[0219] FIG. 2B illustrates the feedback loop of the temperature regulation,

[0220] FIG. 3 illustrates the implementation of the calibration method in an apparatus according to FIG. 1,

[0221] FIG. 4 shows the block diagram of the control system of the apparatus of FIG. 3 in order to enable the implementation of the method of calibration,

[0222] FIGS. 5A to 5D illustrates the implementation of the calibration method,

[0223] FIG. 6 illustrates an embodiment of the process of calibration wherein the preset curve R.sub.set corresponds to a roasting recipe defined for a specific type and weight of coffee beans,

[0224] FIG. 7 illustrates an embodiment of the process of calibration wherein the calibration process is implemented without the need to use coffee beans.

[0225] FIGS. 8A to 8D illustrate the curves that can be obtained in the embodiment illustrated in FIG. 7,

[0226] FIG. 9 illustrates the closed feedback loop of the temperature regulation during the process of calibration of FIG. 7 and FIGS. 8A to 8D,

[0227] FIGS. 10A and 10B illustrate curves that are alternatives to the curve illustrated in FIG. 8D.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0228] Roasting Apparatus

[0229] FIG. 1 shows an illustrative side view part of a roasting apparatus 10. Functionally, the roasting apparatus 10 is operable to roast coffee beans hold in a chamber 1 by means of a flow of hot air introduced inside this chamber. At a first level, the apparatus comprises: a housing 4, a roasting unit and a control system 80. These components will now be sequentially described.

[0230] Roasting Unit of Roasting Apparatus

[0231] The roasting unit is operable to receive and roast coffee beans.

[0232] The roasting unit typically comprises at a second level of the roasting apparatus 10: a chamber 1 and a heating device 2, which are sequentially described.

[0233] The chamber 1 is configured to receive and hold the coffee beans introduced by the operator.

[0234] In the preferred embodiment, the chamber 1 is removable from the housing 4. The chamber can be put aside the roasting apparatus: [0235] for the introduction or the removal of coffee beans, or [0236] for cleaning and maintenance of the chamber once it is removed, or [0237] for cleaning of the vertical housing part 43 behind the chamber.

[0238] The bottom opening 11 of the chamber is configured to enable air to pass through, specifically it can comprise a perforated plate on which the beans can lie and through which air can flow upwardly. The chamber 1 comprises a handle in order to enable the user to remove the chamber from the housing and hold it outside the housing.

[0239] A chaff collector (no illustrated) is in flow communication with the chamber 1 to receive chaffs that progressively separate from the beans and due to their light density are blown off to the chaff collector.

[0240] The heating device 2 comprises an air flow driver 21 and a heater 22.

[0241] The air flow driver 21 is operable to generate a flow of air (dotted lines arrows) in direction of the bottom 11 of the chamber. The generated flow is configured to heat the beans and to agitate and lift the beans. As a result, the beans are homogenously heated. Specifically, the air flow driver can be a fan powered by a motor. Air inlets 42 can be provided inside the base of the housing in order to feed air inside the housing, the air flow driver blowing this air upwardly though a passage 23 to an air outlet hole 41 in direction of the chamber 1 as illustrated by dotted lines arrows.

[0242] The heater 22 is operable to heat the flow of air generated by the air flow driver 21. In the specific illustrated embodiment, the heater is an electrical resistance positioned between the fan 21 and the bottom opening 11 of the chamber with the result that the flow of air is heated before it enters the chamber 1 to heat and to lift the beans. Other types of heater can be used such as an electrical resistor, a ceramic heater, a halogen source, a source of infrared and/or a source of microwaves.

[0243] The heater 22 and/or the air flow driver 21 is/are operable to apply a roasting profile to the beans, this roasting profile being defined as a curve of temperature against time.

[0244] When the chamber is mounted to the housing, the bottom of the chamber is tightly connected to the air outlet hole 41 to avoid that the flow of hot air flow leaks at the connection.

[0245] The top opening 12 of the chamber is connected to a smoke and particulates evacuation device (not illustrated).

[0246] Although the invention is described with a roaster implementing a fluidized bed of hot air, the invention is not limited to this specific type of roasting apparatus. Drum roasters and other kinds of roasters can be used.

[0247] The roasting apparatus comprises at least one first temperature probe 5 to regulate the temperature of air supplied by the heating device 2. This first temperature probe is positioned outside the chamber 1 inside the conduit 23 guiding hot air supplied by the heating device 2 to the bottom of the chamber 11, that is upstream the chamber.

[0248] In an alternative less preferred mode, at least one first temperature probe 51 to regulate the temperature of air supplied by the heating device 2 can be positioned downstream the chamber. This probe can become dirtied by the smoke during roasting operation.

[0249] In another alternative less preferred mode, the apparatus can comprise both first temperature probe 5, 51 to regulate the temperature of air supplied by the heating device 2. The average of the measured temperatures is used to regulate the heating device 2.

[0250] The roasting apparatus 10 usually comprises a user interface 6 enabling the display and the input of information.

[0251] The roasting apparatus can comprise a code reader 7 to read a code associated to a type of coffee beans, for example present on the package of coffee beans. Preferably, this code reader is positioned in the apparatus so that the operator is able to easily position a code in front of it. It is preferably positioned at the front face of the apparatus, for example close to a user interface 6 of the apparatus. Accordingly, information provided by the code can be immediately displayed through the display of the user interface 6 positioned aside.

[0252] Control System of Roasting Apparatus

[0253] With reference to FIGS. 1, 2A and 2B, the control system 80 will now be considered: the control system 80 is operable to control the components of the apparatus to roast coffee beans. The control system 80 typically comprises at a second level of roasting apparatus: the user interface 6, the processing unit 8, an outside temperature probe 5, a power supply 9, a memory unit 63, optionally a database 62, sensors 19, a communication interface 61 for remote connection, a code reader 7 or any combination of these devices.

[0254] The user interface 6 comprises hardware to enable a user to interface with the processing unit 8, by means of user interface signal. More particularly, the user interface receives commands from a user, the user interface signal transfers the said commands to the processing unit 8 as an input. The commands may, for example, be an instruction to execute a roasting process and/or to adjust an operational parameter of the roasting apparatus 10 and/or to power on or off the roasting apparatus 10. The processing unit 8 may also output feedback to the user interface 6 as part of the roasting process, e.g. to indicate the roasting process has been initiated or that a parameter associated with the process has been selected or to indicate the evolution of a parameter during the process or to create an alarm.

[0255] In addition, the user interface can be used to initiate a calibration mode of the roasting apparatus.

[0256] The hardware of the user interface may comprise any suitable device(s), for example, the hardware comprises one or more of the following: buttons, such as a joystick button, knob or press button, joystick, LEDs, graphic or character LDCs, graphical screen with touch sensing and/or screen edge buttons. The user interface 6 can be formed as one unit or a plurality of discrete units.

[0257] A part of the user interface can also be on a mobile app when the apparatus is provided with a communication interface 61 as described below. In that case at least a part of input and output can be transmitted to the mobile device through the communication interface 61.

[0258] The sensors 19 and the temperature probe 5 are operable to provide an input signal to the processing unit 8 for regulating of the roasting process and/or a status of the roasting apparatus. The input signal can be an analogue or digital signal. The sensors 19 typically comprise at least one temperature sensor 5 and optionally one or more of the following sensors: level sensor associated with the chamber 1, air flow rate sensor, position sensor associated with the chamber and/or the chaff collector.

[0259] A code reader 7 can be provided and operable to read a code, for example on coffee beans package, and automatically provide an input that is the identification of the type Cn coffee beans introduced in the chamber 1.

[0260] The processing unit 8 generally comprise memory, input and output system components arranged as an integrated circuit, typically as a microprocessor or a microcontroller. The processing unit 8 may comprise other suitable integrated circuits, such as: an ASIC, a programmable logic device such as a PAL, CPLD, FPGA, PSoC, a system on a chip (SoC), an analogue integrated circuit, such as a controller. For such devices, where appropriate, the aforementioned program code can be considered programmed logic or to additionally comprise programmed logic. The processing unit 8 may also comprise one or more of the aforementioned integrated circuits. An example of the later is several integrated circuits arranged in communication with each other in a modular fashion e.g.: a slave integrated circuit to control the user interface 6 in communication with a master integrated circuit to control the roasting apparatus 10.

[0261] The power supply 9 is operable to supply electrical energy to the said controlled components and the processing unit 8. The power supply 9 may comprise various means, such as a battery or a unit to receive and condition a main electrical supply. The power supply 9 may be operatively linked to part of the user interface 6 for powering on or off the roasting apparatus 10.

[0262] The processing unit 8 generally comprises a memory unit 63 for storage of instructions as program code and optionally data. To this end the memory unit typically comprises: a non-volatile memory e.g. EPROM, EEPROM or Flash for the storage of program code and operating parameters as instructions, volatile memory (RAM) for temporary data storage. The memory unit may comprise separate and/or integrated (e.g. on a die of the semiconductor) memory. For programmable logic devices the instructions can be stored as programmed logic. The instructions stored on the memory unit 63 can be idealised as comprising a coffee beans roasting program.

[0263] The control system 80 is operable to apply this coffee beans roasting program by controlling the heating device 2—that is, in the particular illustrated embodiment of FIG. 1, the air flow driver 21 and/or the heater 22—using signal of the outside temperature probe 5.

[0264] The coffee beans roasting program can effect control of the said components using extraction information encoded on the code and/or other information that may be stored as data on the memory unit 63 or from a remote source through the communication interface 61 and/or input provided via the user interface 6 and/or signal of the sensors 19.

[0265] In particular, the control system 80 is configured to apply a roasting curve R providing the temperature T.sub.@t1, T.sub.@t2, . . . T.sub.@final to be applied at discrete successive times t.sub.1, t.sub.2, . . . , t.sub.final respectively.

[0266] With that aim, the processing unit 8 is operable to: [0267] receive an input T.sub.reg@ti of the outside temperature probe 5, [0268] process the input according to roasting curve R, [0269] provide an output, which is the roasting curve R. More specifically the output comprises the operation of at least the heater 22 and the air flow driver 21.

[0270] The temperature measured by the temperature probe 5 is used to adapt the power of the heater 22 and/or the power of the air driver 21 in a feedback loop in order to apply the roasting curve to the beans for example as illustrated in FIG. 2B.

[0271] In the illustrated feedback loop regulation, the temperature T.sub.reg@ti measured at the outside temperature probe 5 is compared to the temperature T.sub.@ti of the roasting cure to be reproduced. Depending on the difference, the heating device 2 is operated to compensate the difference.

[0272] Depending on the type of control applied in the roaster, the heater 22 can be powered at one pre-determined power, meaning its temperature is constant, and in that case the power of the air driver 21 can be controlled based on the temperature regulated at the probe 5 in order to vary the time of contact of the flow air through the heater during its movement.

[0273] Alternatively, the air driver 21 can be powered at one pre-determined power, meaning the flow rate of air is fixed, and in that case the power of the heater 22 can be controlled based on the temperature regulated at the probe 5 in order to heat more or less air during its passage through the heater.

[0274] In a last alternative, both heater 22 and air driver 21 can be controlled based on the regulation of the temperature by probe 5.

[0275] The control system 80 can comprise a communication interface 61 for data communication of the roasting apparatus 10 with another device and/or system, such as a server system, a mobile device and/or a physically separated measuring apparatus 3. The communication interface 61 can be used to supply and/or receive information related to the coffee beans roasting process, such as roasting process information, type of the beans, quantity of beans.

[0276] The communication interface 61 may comprise first and second communication interface for data communication with several devices at once or communication via different media.

[0277] The communication interface 61 can be configured for cabled media or wireless media or a combination thereof, e.g.: a wired connection, such as RS-232, USB, I2C, Ethernet define by IEEE 802.3, a wireless connection, such as wireless LAN (e.g. IEEE 802.11) or near field communication (NFC) or a cellular system such as GPRS or GSM. The communication interface 61 interfaces with the processing unit 8, by means of a communication interface signal. Generally the communication interface comprises a separate processing unit (examples of which are provided above) to control communication hardware (e.g. an antenna) to interface with the master processing unit 8. However, less complex configurations can be used e.g. a simple wired connection for serial communication directly with the processing unit 8.

[0278] The processing unit 8 enables access to different pre-defined roasting recipes (R.sub.M.sub.A, R.sub.M.sub.B, . . . ), the recipes being adapted to the roasting of specific types of coffee beans or coffee blends (C.sub.A, C.sub.B, . . . ) and preferably specific quantities (M.sub.A, M.sub.B, . . . ) of said beans or blends.

[0279] These recipes can be stored in the memory 13 of the processing unit 8. Alternatively, these data can be stored in a remote server and the processing unit 8 can be supplied with access to this remote server through the communication interface 61, directly or indirectly through a mobile device establishing connection between the remote server and the processing unit.

[0280] The control system 80 can comprise a database 62 storing information about coffee beans, in particular about the operation conditions for roasting specific coffee beans as described hereunder. The database 62 can be stored locally in the memory 63 of the control system of the roasting apparatus or remotely in a server accessible through the communication interface 63.

[0281] In one alternative embodiment, the control system can be provided with the roasting recipes R.sub.M.sub.n (and depending on the embodiment with their associated specific quantities M.sub.n) during a code reading operation, these pieces of information being encoded inside the code and decoded by the control system.

[0282] The pre-defined roasting recipes (R.sub.M.sub.A, R.sub.M.sub.B, . . . ) adapted to the roasting of specific types of coffee beans or coffee blends and specific weight of said beans are defined during an initial operation of roasting these specific beans inside a specific roasting apparatus defined as the master roasting apparatus (M). Usually, this operation is implemented by a coffee expert, who, based on his/her expertise in roasting, is able to define the parameters of temperature and time to optimally roast the specific beans and, as a result, to define the roasting recipe providing a set of points (T.sub.@ti; t.sub.i) representing the temperature T.sub.@t1, T.sub.@t2, . . . to be applied at predefined corresponding successive times t.sub.1, t.sub.2, . . . respectively.

[0283] Once these roasting recipes are pre-defined with the master roasting apparatus, they can be reproduced automatically with roasting apparatus similar to the master roasting apparatus.

[0284] Logically, starting from the same beans and applying the same roasting recipes in roasting apparatuses similar to the master roasting apparatus, the same roasted coffee beans should be obtained. Yet, it has been observed that the reproduction of the roasting was not systematically consistent. Although the temperature probe 5 was perfectly calibrated to measure the correct temperature, non-consistency in the roasting of the same beans was observed between similar roasting apparatuses.

[0285] In the course of the present invention, it was suspected that small differences had appeared between each apparatus during manufacturing. These differences can relate to the use of different key components of the apparatuses (fan, heater, temperature sensor) further to changes in supply sources or to small differences in the assembly of each apparatus, for example creating very small air leakages at various places, or due to the small differences in the relative positions of the key elements one to the other.

[0286] As a result, although the flow of air introduced inside the chamber presented the right temperature as measured by the temperature probe 5, this flow of hot air was received differently inside the chamber with a direct impact on the roasting of the beans.

[0287] In order to solve this problem, a method has been developed to enable the calibration of any new manufactured roasting apparatus so that said apparatus can reproduce consistently the roasting recipes defined with the specific master roasting apparatus.

[0288] The method is illustrated in reference to FIGS. 3, 4 and 5A to 5C.

[0289] FIG. 3 illustrates a roasting apparatus X similar to the roasting apparatus of FIG. 1 during the operation of calibration. The calibration aims at enabling the roasting apparatus X to reproduce coffee beans roasting recipes defined with one specific and similar master roasting apparatus M. During this calibration operation, a secondary temperature probe 5 is introduced inside the chamber 1 temporary.

[0290] By temporary, it is meant that this secondary temperature probe 5 is introduced during the calibration operation only or for other temporary operations (like maintenance check) but not during the normal operation of roasting the coffee beans.

[0291] The secondary temperature probe 5 is connected to the processing unit 8 of the roasting apparatus so that the measure of the temperature inside the chamber T.sub.cal is provided as an input to the control system as illustrated in FIG. 4.

[0292] Before the calibration process of the apparatus X is initiated, in a preliminary stage, the pre-determined calibration curve R.sub.ref is established with the master roasting apparatus M as illustrated in FIG. 5A.

[0293] During this stage, the heating device 2 of the roasting apparatus M is controlled to reproduce a preset curve R.sub.set, said preset curve providing a set of points (T.sub.set@ti; ti) representing the temperature T.sub.set@t1, T.sub.set@t2, . . . T.sub.set@tfinal to be applied at predefined corresponding successive times t.sub.1, t.sub.2, . . . , t.sub.final respectively. This control is based on the temperature T.sub.reg regulated by the first temperature probe 5.

[0294] During the reproduction of the preset curve R.sub.set, the temperature T.sub.ref in the chamber is measured in function of time at the temporary second temperature probe 3. This measure enables the determination of at least a set of points (T.sub.ref@ti; t.sub.i) illustrated in FIG. 5C by the curve T.sub.ref, corresponding to the pre-determined calibration curve R.sub.ref.

[0295] In the same manner, during the calibration process illustrated in FIG. 5B, the heating device 2 of the roasting apparatus X is controlled to reproduce the same preset curve R.sub.set. This control is based on the temperature T.sub.reg regulated by the first temperature probe 5.

[0296] During the reproduction of the preset curve R.sub.set, the temperature T.sub.cal in the chamber 1 is measured in function of time at the temporary second temperature probe 3. This measure enables the determination of at least a set of points (T.sub.cal@ti; t.sub.i) illustrated in FIG. 5C by the curve T.sub.cal.

[0297] In the calibration process of the roasting apparatus X, the temperature T.sub.cal@ti is compared with the temperature T.sub.ref@ti obtained with the master roasting apparatus M at least one same time ti. FIG. 5C illustrates the curves or sets of points corresponding to: [0298] the preset curve Rset, [0299] the temperature T.sub.ref@ti in the chamber of the master roasting apparatus during the reproduction of the preset curve Rset, establishing the pre-determined calibration curve R.sub.ref,

[0300] and [0301] the temperature T.sub.cal@ti in the chamber of the roasting apparatus X during the reproduction of the same preset curve Rset.

[0302] FIG. 5C makes apparent how the reproduction of the same preset curve R.sub.set differs from one apparatus to another. This difference can be explained by differences in the manufacturing process.

[0303] To finalise the calibration of the roasting apparatus X, based on the comparison between T.sub.cal and T.sub.ref, a correction is applied in the feedback loop regulation of the apparatus X so that, when the control system of the apparatus X will reproduce the preset curve R.sub.set, the desired temperature T.sub.ref is obtained inside the chamber of the apparatus X, as illustrated schematically in FIG. 5D.

[0304] Different types of correction can be applied depending on the relationship between T.sub.cal and T.sub.ref. The complexity of the relationship can depend on: the differences of construction between the roasting apparatus and the master roasting apparatus such as the use of another type of heater, another shape of chamber, another control rule or algorithm to control the heater (e.g. more complex if there are 2 degrees of control on air flow driver and heater) providing for example a more sensitive control.

[0305] The relation is usually determined though regression analysis and implemented by means of a regression analysis software using well-known analysis models such as linear regression, multiple regression, non-linear regression, polynomial regression, . . . .

[0306] Once the relationship between T.sub.cal and T.sub.ref is defined, a correction can be applied to the rule or algorithm applied by the feedback loop regulation. The correction can be applied at different steps of this rule depending on the complexity of this rule. In the simplest embodiments, preferably the correction is applied to the temperature T.sub.reg measured by the first temperature probe 5 or to the temperatures T.sub.@ti provided by the roasting curves to be reproduced.

[0307] In the case of roasters M and X illustrated in FIGS. 5A and 5B, where both roasters comprise very similar components with a simple feedback loop control operating the heater 22 only based on the temperature measured by the temperature probe 5 a factor of correction can be defined through the ratio K at time t.sub.final:

[00008]$\frac{T_{\mathrm{cal}@\mathrm{tfinal}}}{T_{ch@\mathrm{tfinal}}}$

[0308] This ratio can be used as simple multiplication factor of the temperature T.sub.@ti provided by the roasting curves to be reproduced before being compared to T.sub.reg in the feedback loop regulation.

[0309] In another embodiment of the invention, the inverse of the above ratio, that is

[00009]$\frac{1}{K},$

can be used as multiplication factor of the temperature T.sub.reg measured by the first temperature probe 5, before this temperature being compared to T.sub.@ti in the feedback loop regulation.

[0310] The correction enables the control system of the apparatus X to supply hot air inside the chamber at a temperature that is closer to the temperature T.sub.ref obtained in the master apparatus.

[0311] Accordingly, further to the calibration process, during roasting operation with the roasting apparatus X, predefined coffee beans roasting recipes R defined for specific beans with the master roasting apparatus M can be reproduced accurately by the control system applying the above ratio to the measure of the temperature regulated at the first probe 5 to control the heating device 5 or to the temperature T.sub.@ti provided by the roasting curves to be reproduced.

[0312] The calibration process can be applied with different alternatives relative to: [0313] the type of comparison between the temperatures T.sub.ref and T.sub.cal, and/or [0314] the implementation of iteration in the calibration process reiterating the process with even more precise correction and/or [0315] the type of preset curve R.sub.set used in the process, and/or [0316] the presence of coffee beans inside the chamber or not during the calibration process.

[0317] These alternatives can provide more or less accuracy to the calibration and the further consistent reproduction of roasting recipes.

[0318] FIG. 6 illustrates an embodiment of the process of calibration wherein the preset curve R.sub.set corresponds to a roasting recipe defined for a specific type and quantity of coffee beans. In this process: [0319] in a first preliminary stage 6a, the preset curve R.sub.set corresponding to a roasting recipe is created with the master roasting apparatus M roasting a specific type and quantity of coffee beans. This creation is usually the work of a coffee expert with the objective of providing the optimal taste to the roasted coffee beans, eventually in view of a specific type of extraction (espresso, filter, cold brew, . . . ) [0320] in a further preliminary step 6b, these coffee beans of specific type and quantity are roasted again in the master roasting apparatus M by controlling the heating device in order to reproduce said curve R.sub.set based on the measure of temperature with the first temperature probe 5, and simultaneously the temperature T.sub.ref is measured in the chamber by a second temporary probe 3 introduced inside the chamber, [0321] then the process of calibration of apparatus X is implemented: these coffee beans of specific type and quantity are roasted in the roasting apparatus X to be calibrated by controlling the heating device in order to reproduce said curve R.sub.set based on the measure of temperature with the first temperature probe 5, and simultaneously the temperature T.sub.cal is measured in the chamber by a second temporary probe 3 (6c in FIG. 6).

[0322] In a further step, the temperature T.sub.ref@ti and T.sub.cal@ti measured in the respective chambers by the second temporary probe 3 are compared. In one preferred embodiment, the comparison comprises calculating the ratio T.sub.ref@ti/T.sub.cal@ti at the final time t.sub.final of the curves R.sub.ref and R.sub.cal and applying this ratio as factor of correction to the temperature T.sub.set to be reproduced or applying the inverse of this ratio as factor of correction to the temperature T.sub.reg measured by the temperature probe 5 in the roasting apparatus X (6d in FIG. 6)

[0323] Preferably the step 6c is reproduced while applying this just determined factor of correction and a new more accurate factor of correction can be determined in the feedback loop regulation. The operation can be re-iterated again.

[0324] This embodiment can present some drawbacks: [0325] it requires the roasting of important quantities of coffee beans which are useless. This is a waste. [0326] it requires time for the operator to introduce beans and to implement the successive iterations. In particular, it is recommended to wait time between two roasting operations in order to let the roasting apparatus cool down and to be able to always repeat the roasting operation in the same conditions. [0327] the human operation can create errors (beans weighting for example) with direct impact on the calibration. [0328] the calibration depends on the properties of beans which can vary with time, [0329] the new apparatus requires cleaning before being sold.

[0330] To solve these drawbacks, the coffee beans can be replaced by granular inert objects like glass of beads.

[0331] FIG. 7 illustrates an embodiment of the process of calibration wherein the calibration process is implemented without the need to use coffee beans.

[0332] In this process, the preset curve R.sub.set is a curve established without relationship to any particular type or weight of coffee beans.

[0333] Similarly to the previous described embodiment: [0334] in a first preliminary stage 7a, a preset curve R.sub.set is reproduced in the master roasting apparatus M based on the regulation n of temperature with the first temperature probe 5, and simultaneously the temperature T.sub.ref is measured in the chamber by a second temporary probe 3 introduced inside the chamber. A calibration curve R.sub.ref or a set of points representing T.sub.ref in function of time is established. [0335] then the process of calibration of the roasting apparatus X is implemented: [0336] the heating device of the apparatus X is controlled in order to reproduce said curve R.sub.set based on the regulation of temperature with the first temperature probe 5, and simultaneously the temperature T.sub.cal is measured in the chamber by a second temporary probe 3 introduced inside the chamber (7b in FIG. 7). A curve or a set of point R.sub.cal representing T.sub.cal in function of time is established. [0337] in a further step or simultaneously, this temperature T.sub.cal@ti measured in the chambers by the second temporary probes 3 is compared to previously determined T.sub.ref@ti and a calibration correction K is deduced (7c in FIG. 7).

[0338] FIGS. 8A to 8D illustrate the curves that can be obtained in the embodiment illustrated in FIG. 7.

[0339] FIG. 8A illustrates the preferred profile of a preset curve R.sub.set that does not need to reproduce a profile corresponding to a roasting recipe. Preferably, this curve provides a set of points (T.sub.set@tset i; t.sub.set i) and comprises successively: [0340] in a first phase, a plateau of the temperature T.sub.set at a fixed temperature T.sub.set-stab, then [0341] in a second phase, an increase of temperature T.sub.set from T.sub.set-stab to a higher temperature T.sub.set-high, then [0342] in a third phase, a plateau of the temperature T.sub.set at said temperature T.sub.set-high. [0343] in a fourth phase, a cooling during which heating is stopped.

[0344] Consequently, this preset curve R.sub.set can be defined with three points: (T.sub.set-stab; t.sub.stab), (T.sub.set-high; t.sub.high) and (T.sub.set-high, t.sub.end).

[0345] As mentioned earlier, in the first phase, the fixed temperature T.sub.set-stab is preferably defined as a temperature that can be rapidly reached by the roasting apparatus whatever the ambient temperature of the room where it is used, for example a temperature of about 40° C. The length of this first phase must be sufficient to enable the heating of cold apparatus or the cooling of hot apparatus (if it has been previously used) until a stabilisation state. The length can vary from one type of apparatus to another, in particular from the power of the heating device, the heat exchange with the outside.

[0346] Generally few minutes can be sufficient.

[0347] In the second and third phases, the temperature T.sub.set-high to be reached and maintained can depend again on the on the type of heating device used in the roasting apparatus, and in particular on the type of regulation of the power provided to the heating device. For an electric heating device where the air blower is kept at the same speed and where regulation is operated by adapting the power of the electrical resistance only, the temperature T.sub.set-high is preferably set in a stable operating zone of the electrical resistance. Accordingly, maintaining the electrical resistance in said zone does not create important deviations during the regulation.

[0348] The presence of a plateau in the third phase enables the stabilisation of temperature and a more reliable comparison with R.sub.cal along this plateau rather than in zone of fast change of temperature like in the increase at the beginning the second phase.

[0349] In a roasting apparatus such as illustrated in FIG. 1, the curve R.sub.set can be defined as follows: [0350] T.sub.set-stab=40° C. [0351] t.sub.stab in the range of 7 to 10 minutes [0352] T.sub.set-high in the range of 100 to 200° C. [0353] t.sub.end in the range of 4 to 6 minutes.

[0354] FIG. 8B illustrates the curve R.sub.ref obtained during the implementation of the first preliminary stage (such as illustrated in step 7a in FIG. 7) where the preset curve R.sub.set is reproduced in the master roasting apparatus M based on the temperature measured with the first temperature probe 5, and where simultaneously the temperature T.sub.ref is measured in the chamber by a second temporary probe 3 introduced inside the chamber. A calibration curve R.sub.ref comprising a set of points (T.sub.ref@ti; t.sub.i) representing T.sub.ref in function of time is determined as illustrated by white dots. Preferably, the points are determined at predefined times t.sub.ref i that are in the parts of the curve R.sub.set comprising a plateau.

[0355] As illustrated in FIG. 8B, at least one predefined time t.sub.ref 1 is defined in the first phase and at least two predefined time t.sub.ref 2 to t.sub.ref 7 are defined in the third phase.

[0356] FIG. 8C illustrates the curve R.sub.cal obtained during the implementation of the calibration process of the roasting apparatus X where the heating device of the apparatus X is controlled in order to reproduce the curve R.sub.set based on the measure of temperature with the first temperature probe 5, and where simultaneously the temperature T.sub.cal is measured in the chamber by a second temporary probe 3 introduced inside the chamber (as illustrated in step 7b in FIG. 7). A curve R.sub.cal comprising a set of points (T.sub.cal@ti; t.sub.i) representing T.sub.cal in function of time is established as illustrated and T.sub.cal is measured at the predefined times t.sub.ref i establishing a set of points (T.sub.cal@tref i; t.sub.ref i) representing T.sub.cal in function of time as illustrated by black dots.

[0357] In the embodiment of FIG. 8C, during the reproduction of the preset curve R.sub.set, at the predefined times t.sub.ref i, the corresponding temperatures T.sub.ref@tref i and T.sub.cal@tref i can be compared and a correction is immediately applied inside the control system of the roasting apparatus.

[0358] In one preferred embodiment, illustrated by the curve in FIG. 8D, during the reproduction of the preset curve R.sub.set by the apparatus X, at predefined times t.sub.ref i (as determined in FIG. 8C), the corresponding ratio T.sub.ref@tref i/T.sub.cal@tref i is calculated and a factor of correction is immediately applied to the temperatures T.sub.set@ti to be reproduced by the roasting apparatus X, said factor of correction corresponding to the ratio Ki defined as follows:

[00010]$K_i=\underset{n=1}{\overset{i}{.Math.}}\frac{T_{\mathrm{ref}@\mathrm{trefn}}}{T_{c\mathrm{al}@\mathrm{trefn}}}$

[0359] FIG. 8D illustrates the evolution of this ratio Ki at the different predefined times t.sub.ref i. The immediate application of the correction in the control system after each calculated ratio enables the determination of a convergent value for this ratio in one single operation of calibration.

[0360] This final convergent value K.sub.7 obtained at t.sub.cal7 is used to calibrate the roasting apparatus by applying said multiplication factor to the temperatures T.sub.@ti of the roasting curves established with the master roasting apparatus M and to be reproduced by the roasting apparatus X.

[0361] Alternatively, the final convergent value K.sub.7 obtained at t.sub.cal7 can be used to calibrate the roasting apparatus by applying the multiplication factor

[00011]$\frac{1}{K7}$

to the temperature T.sub.reg measured by the first temperate probe 5 inside the control system of the roasting apparatus X.

[0362] Depending on the evolution of the convergence of the calculated ratio K to a fixed value, the process of calibration can be stopped earlier.

[0363] FIG. 9A illustrates the closed feedback loop of the temperature regulation during the process of calibration of FIG. 7 (steps 7b, 7c) and FIGS. 8A to 8D.

[0364] During the reproduction of the preset curve R.sub.set, at the predefined times t.sub.ref i (i=1 to n), the temperature T.sub.cal@tref i is measured in the chamber at the second temperature probe 3 and is inputted in the control unit 8. It is compared to the corresponding predetermined temperature T.sub.ref@tref i, here the comparison consists in calculating the ratio Ki as follows:

[00012]$K_i=\underset{n=1}{\overset{i}{.Math.}}\frac{T_{\mathrm{ref}@\mathrm{trefn}}}{T_{c\mathrm{al}@\mathrm{trefn}}}$

[0365] Then, this ratio Ki is immediately used to correct the temperature T.sub.set inside the feedback loop of the temperature regulation: accordingly, in the illustrated example the inputted value T.sub.set@ti is inputted as Ki×T.sub.set@ti when compared to T.sub.reg@ti in the feedback loop.

[0366] FIG. 9B illustrates an alternative method of calibration to the one implemented in FIG. 9A.

[0367] FIG. 9B illustrates the closed feedback loop of the temperature regulation during the process of calibration of FIG. 7 (steps 7b, 7c) and FIGS. 8A to 8D.

[0368] During the reproduction of the preset curve R.sub.set, at the predefined times t.sub.ref i (i=1 to n), the temperature T.sub.cal@tref i is measured in the chamber at the second temperature probe 3 and is inputted in the control unit 8. It is compared to the corresponding predetermined temperature T.sub.ref@tref i, here the comparison consists in calculating the ratio Ki as follows:

[00013]$K_i=\underset{n=1}{\overset{i}{.Math.}}\frac{T_{\mathrm{ref}@\mathrm{trefn}}}{T_{c\mathrm{al}@\mathrm{trefn}}}$

[0369] Then, this ratio Ki is immediately used to correct the temperature T.sub.reg inside the feedback loop of the temperature regulation: accordingly, in the illustrated example the measured value T.sub.reg@ti is inputted as

[00014]$\frac{\mathrm{Treg}@\mathrm{ti}}{\mathrm{Ki}}$

when compared to T.sub.set@ti in the feedback loop.

[0370] In the process illustrated in FIG. 7 (steps 7b, 7c), 8A to 8D and 9A and 9B, if the apparatus X to be calibrated is part of a series of similar manufactured apparatuses for which calibration method has already been implemented, then a preset factor K.sub.0 could be pre-determined for that series. Accordingly, in order to shorten the process of calibration of the apparatus X, this factor K.sub.0 could be used in the calculation of the factor of correction illustrated in FIG. 8D as follows:

[00015]$K_i=K_0\underset{n=1}{\overset{i}{.Math.}}\frac{T_{\mathrm{ref}@\mathrm{tref}n}}{T_{c\mathrm{al}@\mathrm{tref}n}}$

[0371] FIGS. 10A and 10B illustrate two different situations.

[0372] FIG. 10A illustrates the situation where the successive calculated ratios T.sub.ref@tref i/T.sub.cal@tref i become closer one to the other with time. It can be set that, if at one t.sub.ref i, the corresponding calculated ratio T.sub.ref@tref i/T.sub.cal@tref i differs by less than 2% from the previous calculated ratio T.sub.ref@tref i−1/T.sub.cal@tref i−1, then the reproduction of the preset curve R.sub.set as illustrated in FIG. 8C can be stopped. The last calculated ratio Ki can be used as the factor of correction of the apparatus X. In the illustrated curve, the ratio T.sub.ref@tref 5/T.sub.cal@tref 5 is very close to T.sub.ref@tref 4/T.sub.cal@tref 4, meaning that the step c) of the calibration process can be stopped at t.sub.cal5 already.

[0373] FIG. 10B illustrates the situation where the successive calculated ratio T.sub.ref@tref i/T.sub.cal@tref i do not converge. It can be set that, if at successive t.sub.ref i, the corresponding calculated ratio T.sub.ref@tref i/T.sub.cal@tref i increases by more than 20%, then the calibration process is stopped. In the illustrated curve, the ratio T.sub.ref@tref i/T.sub.cal@tref i does not converge after t.sub.6 meaning that a factor K cannot be defined. The process of calibration is failing and must be stopped. Such a situation reveals that the method has not been operated correctly or the apparatus is broken or presents such a default that it cannot be operated normally and calibrated.

[0374] It can be suggested to re-start the calibration process. If the calibration process fails again, maintenance shall be required.

[0375] The operator can be guided to implement these different steps through the display of the apparatus in an automatic manner.

[0376] Alternatively, it can be estimated that the successive calculated ratios do not converge when the ratios reach pre-determined upper and lower values, such as for example inferior to 0.5 or superior to 2. If such ratios are monitored, then the process is stopped.

[0377] Preferably, in the embodiment where the calibration process is implemented with the apparatus void of beans, means configured to simulate the presence of coffee beans are introduced inside the chamber of the apparatus X or are present inside the temporary calibration chamber positioned inside the apparatus X during the calibration process.

[0378] In that case, the reference curve R.sub.ref determined with the master apparatus is established in the same conditions that will be used for the calibration process of the roasting apparatus X: a master apparatus presenting the same means to simulate beans or using the same calibration jug.

[0379] Alternatively, in the embodiment where the calibration process is implemented with the apparatus X void of beans, and where the control system of the roasting apparatus X is configured to control the heating device to control the flow of air supplied to the chamber, then in the step b) of the calibration process, the heating device is preferably controlled to reproduce the value of the flow of air generated in presence of coffee beans inside the chamber.

[0380] In that case, the reference curve R.sub.set determined with the master apparatus is established with the same conditions that are: a master apparatus presenting the same flow of hot air.

[0381] In the above described embodiments of the calibration process, the value of the temperature T.sub.cal@ti measured at the second temperature probe 3 can be adjusted to an adjusted value T.sub.cal@ti-adjusted that is specific to said second temperature probe.

[0382] This adjustment of the temperature is not necessary if there is only one single second temporary probe 3 to determine the pre-determined reference curve Rref obtained with the master roasting apparatus and to calibrate all the roasting apparatuses subsequently, as illustrated in the preliminary step 6b and the calibration step 6c of FIG. 6.

[0383] Yet, when multiple different second temporary probes 3 or temporary calibration chambers exist (which becomes necessary when an important number of roasting apparatuses are commercialised), the measures of these probes or chambers are compared to the measures of the original second temporary probe 3 or to another already calibrated second temporary probe 3. Based on this comparison, a new second temporary probe 3 can be used in a calibration process of a roasting apparatus such as described above.

[0384] Preferably, [0385] the value of the temperature T.sub.cal@ti measured at the new second temperature probe at step c) can be adjusted to an adjusted value T.sub.cal@ti-adjusted,

[0386] and [0387] in step d) this adjusted value T.sub.cal@ti-adjusted can be compared with the temperature T.sub.ref@ti.

[0388] For the operation of comparison of the measures of new second temporary probe with the measures of the original second temporary probe 3 or to another already calibrated second temporary probe 3, a temperature versus time curve of reference is reproduced, for example a curve such as illustrated in FIG. 8A. Then, based on this comparison, the adjustment of the measure of temperature of the new second temporary probe can be defined.

[0389] Different types of adjustment can be applied depending on the relationship between the temperatures of the two probes. The complexity of the relationship can depend on: the differences of construction between them such as the use of a new type of probe, another shape of chamber, a new position of the probe inside the temporary chamber, . . . .

[0390] The relation can be determined though regression analysis and implemented by means of a regression analysis software using well-known analysis models such as linear regression, multiple regression, non-linear regression, polynomial regression, . . . .

[0391] In one preferred process:

T.sub.cal@ti-adjusted=K.sub.2probe.Math.(T.sub.cal@ti).sup.2+K.sub.1probe.Math.T.sub.cal@ti+T.sub.probe

[0392] wherein the preset temperature offset T.sub.probe and the preset temperature ratios K.sub.1probe and K.sub.2probe are defined by regression analysis software.

[0393] The calibration process of the present invention was implemented on a model of roasting apparatuses presenting the features of the apparatus of FIG. 1.

[0394] A series of roasting apparatuses was produced as copies of the master roasting apparatus with which roasting recipes were established. Without applying the calibration process to the roasting apparatuses of the series similar to the master roasting apparatus, it was observed that the roasting of same beans according to the same roasting recipe produced roasted beans of different colours from one apparatus to another which was the evidence of absence of consistent roasting. The measure of the temperature inside the chambers of these different apparatus showed a difference of about 10% with the master apparatus, that is a difference of 20 to 25° C. when a temperature of 200° C. was requested.

[0395] By implementing the calibration method in each roasting apparatuses of the series, this difference was reduced to about 1° C. and it was confirmed that beans of same colour were obtained.

[0396] The calibration process of the present invention presents the advantages of: [0397] enabling the consistent reproduction of coffee beans recipes defined by an expert on a master roasting apparatus with any similar and new manufactured roasting apparatus, [0398] enabling automatic implementation. [0399] in some embodiments, avoiding the waste of coffee and operator's time, and not necessitating any cleaning operation,

[0400] Although the invention has been described with reference to the above illustrated embodiments, it will be appreciated that the invention as claimed is not limited in any way by these illustrated embodiments.

[0401] Variations and modifications may be made without departing from the scope of the invention as defined in the claims. Furthermore, where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred in this specification.

[0402] As used in this specification, the words “comprises”, “comprising”, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to”.

LIST OF REFERENCES IN THE DRAWINGS

[0403] roasting apparatus 10 [0404] chamber 1 [0405] bottom opening 11 [0406] top opening 12 [0407] heating device 2 [0408] air flow driver 21 [0409] heater 22 [0410] passage 23 [0411] second temperature probe 3 [0412] housing 4 [0413] air outlet hole 41 [0414] air inlets 42 [0415] vertical housing part 43 [0416] first temperature probe 5, 51 [0417] user interface 6 [0418] code reader 7 [0419] processing unit 8 [0420] control system 80 [0421] power supply 9 [0422] sensor 19 [0423] communication interface 61 [0424] database 62 [0425] memory unit 63