FR2806784A1 - IMPROVED COOKING DEVICE WITH DECONTAMINATION CONTROL, AND ASSOCIATED METHOD - Google Patents

Abstract

A cooking device comprises an enclosure (2) for food (3) provided with heating means (4) with controlled operation, and ambient (6) and internal (7) temperature probes, input means (8) of internal and ambient cooking temperatures and a minimum decontamination value, and a control module (5) to control the heating means according to parameters of a byte according to the ambient and internal temperatures entered and the decontamination value entered .

Description

IMPROVED COOKING DEVICE WITH REGULATION OF

DECONTAMINATION AND ASSOCIATED METHOD

  The invention relates to the field of cooking food products. It relates more particularly to cooking devices, such as ovens, atmosphere (or atmosphere) regulated. These devices comprise receiving means (such as an enclosure) provided with heating means controlled by a control module, an ambient temperature probe and means for determining the

  temperature inside a food.

  The user supplies the control module with a set room temperature, which designates the temperature that must prevail in the enclosure during cooking, and an internal setpoint temperature, which designates the temperature that must prevail inside the food. end of cooking. The control module then determines the operating parameters of the heating means that will allow the internal temperature measured in the food to evolve towards the internal temperature setpoint. When the latter is reached, the cooking is 2 o completed and it is possible to calculate a decontamination value, usually a pasteurization value, which allows the user to

  determine the shelf life of the food.

  This type of device provides excellent control of the cooking conditions, but it does not allow the user to choose a value of

decontamination.

  The invention therefore aims to solve this problem.

  It proposes for this purpose a cooking device comprising in combination: * a receiving means (such as an enclosure, or more generally a container) for receiving at least one food to be cooked and provided with controlled operation heating means, an ambient temperature probe and means for measuring the internal temperature of the food, input means enabling a user to record the internal and ambient temperatures that he considers appropriate for cooking the food, and a minimum decontamination value, and * a control module for determining, from the entered ambient and internal temperatures and the decontamination value entered, a multiplet of cooking parameters (set of n parameters, n being greater than or equal to to 1) and to operate the heating means according to the parameters of this multiplet, so that the value of decontamination at the end of cooking is higher ure or equal to said decontamination value entered. Thus, it is possible to impose on the cooked food a value of

  decontamination while preserving its gustative and nutritive values.

  In a particularly advantageous embodiment, the control module is arranged to deduce, at selected intervals, a decontamination value in progress from, in particular, internal temperature measurements, to compare each current decontamination value with the value decontamination method and each internal temperature measured at the internal temperature entered, and to interrupt the operation of the heating means when the measured internal temperature is substantially equal to the internal temperature entered and that at the same time the current decontamination value is greater or

equal to the value entered.

  In this case, the control module may be arranged to make comparisons between the measured ambient temperature and each measured internal temperature, and to adapt at least some of the parameters of the multiplet according to the result of each comparison, so that that the measured ambient temperature remains substantially greater than or equal to the internal temperature. Of course, the adaptation takes place only when necessary, for example when the measured internal temperature and / or the measured ambient temperature varies (nt). Advantageously, the multiplet comprises at least a maximum ambient operating temperature associated with the ambient temperature entered, a maximum ambient rise speed and a rate of decrease of the ambient temperature between this maximum ambient temperature and a minimum ambient temperature associated with the internal temperature entered. This multiplet can be calculated using a

  zo software module, or using a specific electronic circuit.

  As needed, the decontamination value can be either a pasteurization value (or pasteurizer value) or a value of

  sterilization (or sterilizing value).

  The invention also relates to a cooking process for placing

  implementation of the device presented above.

  Other features and advantages of the invention will appear in

  examination of the following detailed description, and the accompanying drawings, on

  which: - Figure 1 is a block diagram illustrating very schematically a cooking device according to the invention, - Figure 2 is a graph illustrating the evolution as a function of time ambient and internal temperatures measured for a type of FIG. 3 is a first example of an algorithm illustrating a cooking method according to the invention, and FIG. 4 is a second example of an algorithm illustrating a process.

cooking according to the invention.

  The attached drawings are, for the most part, of a certain character. Consequently, they can not only serve to complete the invention, but

  also contribute to its definition, as appropriate.

  In the description that follows, reference will be made to a furnace of

  cooking, but the invention applies more generally to any type of controlled environment cooking device. Here we mean by "ambiance" the

  medium in which the food is to be cooked.

  The oven 1 illustrated very schematically in FIG. 1 comprises a cooking chamber 2 suitable for receiving one or more

  food 3 in one or more levels.

  The enclosure 2 comprises one or more heating means 4 so as to allow one or more types of cooking, for example

  steaming, forced air cooking, micro-cooking

  waves or different combinations of these types of cooking. These heating means 4 are controlled by a control module 5 according to a mode that

will be described later.

  This chamber can also be adapted to other cooking modes, such as for example cooking under vacuum, or cooking at low temperature.

temperature.

  The chamber 2 also houses a first temperature sensor 6 intended to provide measurements representative of the ambient temperature inside the enclosure, and means 7 for determining the temperature inside the foodstuff. . The means 7 are preferably made in the form of a probe called "heart" that is introduced into the food 3. But, of course, any other type of internal temperature evaluation means can be used , such as a detector

  performing absorption measurements.

  The ambient temperature probe 6 and the internal temperature sensor 7 deliver their measurements of ambient temperature TambM and of internal temperature TintM to the control module 5, so that it can regulate the cooking, and consequently the atmosphere prevailing at room temperature. inside

the enclosure 2.

  The control module 5 receives its cooking "instructions" from an input module 8 placed, preferably, on the front of the oven 1. This input module 8 comprises, for example, digital keys 9, 11 and 12 allowing recording the cooking parameters, and in particular the room temperature Tambs and the internal temperature Tints. These ambient and internal temperatures can be, for example, defined by two selection keys 9, one for decrementing the value displayed on a screen 10, for example of the LCD type, the other for incrementing this value. The value thus defined by the user is stored by a continuous pressure exerted on a digital key 11,

for example.

  The selection of the cooking parameters to be defined (using the keys 9) is made with another digital key 12. For example, a first press on the key 12 makes it possible to define the value of the room temperature Tambs with the keys incrementing / decrementing 9, while a second pressure will allow to set the value of the internal temperature Tints with these same keys 9. The ambient temperature entered Tambs is actually a maximum ambient temperature TambMAx <cooking (TambMAx = Tambs), while the internal temperature Tints Tints is actually a temperature

  minimal internal TintMIN (TintMIN = Tints).

  Of course, any other type of input means can be envisaged, including remote input means, remote control type infrared data transmission. Mechanical input means can also be envisaged, each parameter being

  controlled by a slider or rotary knob.

  Whatever the type of input means 8 used, the cooking parameters defined (entered) by the user are sent to the control module 5 which stores them in a memory 13 in order to develop the

cooking program.

  According to the invention, the input module 8 is also arranged to allow the user to set, before the start of cooking a decontamination value VDs. The importance of decontamination value increases

  with the possible shelf life of the food to be cooked.

  The decontamination value VD may be a pasteurization value VP or a sterilization value VS, or any other significant cooking value. Pasteurization refers to a heat treatment that destroys more or less extensively the microbial species in their vegetative form. It aims to avoid certain risks related to the presence and proliferation of non-sporulating pathogenic bacteria. As known to those skilled in the art, pasteurization can extend the life of a food, provided that it is not recontaminated and that its conservation is done at

  a suitable temperature, for example at 3 C.

  The value of pasteurization VP is defined by the integration of a time / temperature pair, and makes it possible to determine the rate of destruction of a given microorganism in a food (the reference source of the seedling). This value makes it possible to arbitrarily determine the shelf life of the food under the conditions mentioned above. Sterilization also refers to a heat treatment destroying in a more or less extensive way, not only the species in their vegetative form, but also in their sporulated form. This sterilization will allow the food to be stored at room temperature, and of course in a sterile environment, during a

relatively long period.

  The value of pasteurization is well known to those skilled in the art. It can be defined by the following formula: el VP = f 10r (TA) /Z.dt t r2 where T is the internal temperature Tint, Z and A are constants which depend on the reference bacterium (for example Z = 10 C and A = 70 C

  in the case of Streptococcus faecalis), and t denotes the integration time.

  The sterilizing value has a formulation similar to that of the pasteurizing value. The reference temperature is raised to 121 C (corresponding to the usual temperature in the autoclaves) and the value of the constant Z is equal to 10 C (value of Z associated with Clostridium

  sporogen and Clostridium botulinum).

  With the formula indicated above, when the decontamination value VDs is set, the time tH during which the feed must be maintained at an internal temperature greater than or equal to an internal temperature associated with VD (TintvD) is obtained, but below (or level) of the user-entered Tints internal temperature. More

  temperature Tint is low plus duration tH tends to infinity.

  By way of example, for a pasteurization value equal to approximately 100, and an internal temperature equal to 70 ° C., the holding time is substantially equal to one hour and forty minutes. While a temperature Tint equal to 60 C gives, in the case of the aforementioned reference bacterium,

  a VP of 10 for the same duration of temperature maintenance.

  The control module 5 comprises calculation means for determining the duration tH during which the food 3, placed in the chamber 2, must be maintained above an internal temperature TintvD (which will be discussed later), but below (or at the level of) the Tints internal temperature entered by the user. These calculation means are arranged to calculate in real time the decontamination value VD in function, at the

  the measured internal temperature TintM and the elapsed time.

  This calculation is, of course, established with reference to a given microorganism. Therefore, the memory 13 of the control module 5 can be arranged to store several different values for the constants Z and A, adapted to several different types of microorganisms. In this case, it is advantageous for the user to select a microorganism from the selection offered, while at the same time defining the

other cooking parameters.

  The calculation means of the control module 5 are also adapted to determine the energy that the heating means 4 must provide for the cooking corresponds to the parameters entered by the user. The calculation means determine, in fact, the evolution of the ambient temperature as a function of time, which amounts to fixing at each instant the temperature which must reign inside the enclosure 2 and therefore the energy that the heating means must radiate. The curve of the measured ambient temperature TambM must be substantially identical to the evolution determined by the calculation means 5. Such a curve TambM = f (t) is illustrated, by way of example, in FIG. 2 (by dashes ). This curve increases rapidly in the time interval between the instants t = 0 and t ", then decreases slowly between the instants t, and t2 .The interval [0; tl] defines the rise time towards the maximum ambient temperature TMax and therefore the rate of rise in temperature.This maximum ambient temperature

  TMax is actually the ambient temperature entered by the user (Tambs).

  The time interval [t,; tj defines the time of descent from the maximum ambient temperature TMax to a minimum value TMi, (materialized by the horizontal continuous line) which is in fact equal to the internal temperature Tints

entered by the user.

  The ambient temperature must tend, by a higher value, to this value TMf, which defines the maximum internal temperature beyond which the nutritional and taste qualities of the food 3 may be

degraded.

  On this same figure 2 is also illustrated, in the part

  lower, the evolution of the internal temperature TintM as a function of time.

  The evolution of this internal temperature depends on the temperature inside the enclosure 2, and consequently on the evolution of the

  room temperature TambM which is fixed by the control module 5.

  FIG. 2 also shows, in dotted lines, the minimum internal temperature TintvD associated by the control module 5 with the internal temperature Tints captured to measure the decontamination value VD. Indeed, as indicated above, the decontamination value is caculated over the interval [TintvD; Tints]. In the example shown, the minimum internal temperature TintvD is set at 48 C, while the internal temperature Tints entered by the user is 65 C. TintvD is set arbitrarily at 48 C, for safety reasons, so that

  Microbial proliferation risks in some products are limited.

  Of course, it is possible to adapt the calculation module 5 so that it

  allows the user to set the value of TintvD.

  The measured internal temperature TintM tends towards the internal temperature Tints captured. The hatched area, which refers to the area between the dotted line and the TintM curve, defines the value of

VD decontamination.

  By fixing the curve of evolution of the ambient temperature prevailing in the chamber 2 and the decontamination value VD, we therefore control

  the evolution of the internal temperature that must reign inside the food 3.

  The calculation module will therefore determine, from the parameters entered by the user (Tambs, Tints and VD), a multiplet of parameters comprising, at least, the maximum ambient temperature TMax, the rise time (and therefore the speed up) to reach this maximum ambient temperature (interval [0; t1]) and the descent time (and thus the descent rate) from the maximum ambient temperature to the entered internal temperature (interval [t,; tJ)) . These multiplet parameters

  allow the control module 5 to control the heating means 4.

  Advantageously, the control module according to the invention is a microprocessor comprising EEPROM type memories and RAM memories. Furthermore, the calculation means of the control module are preferably constituted by electronic circuits controlled by

stored software modules.

  The control module can also be arranged to store the data representative of each cooking, in order to ensure traceability. On the other hand, there is described a device in which the user entered cooking parameters (ambient temperature, internal temperature and decontamination value). But, the control module can be arranged to memorize cooking programs comprising different sets of cooking parameters, the user only having to choose a cooking program and thus a set of three parameters among those memorized . It is also possible to consider storage of the sets of parameters so that the user can reuse them later. The word "seizure" must therefore be understood

in a broad definition.

  Reference is now made to FIG. 3 to describe a preferred example of a method according to the invention, making it possible to implement the

  device which has just been described with reference to Figures 1 and 2.

  In a step 100, the user enters at least the cooking parameters Tambs = TambMa ,, Tints = TintMin and VDs = VDMin. These parameters are then stored in the memory 13 of the control module 5. As indicated above, the user could also enter other auxiliary parameters, such as for example the reference microorganism (selection of constants Z and A) and / or the minimum internal temperature TintVD. In a step 110, the control module checks whether the temperatures entered are not outliers. To do this, it checks, on the one hand, if TintMin is strictly superior to TintvD and, on the other hand, if TambM. is

strictly superior to TintMfl.

  If the result of this double test is negative, an error message is displayed on the oven entry screen and the user is asked to reconsider

  the cooking parameters he has just entered.

  On the other hand, if the result of this double test is positive, the control module 5 determines in a step 120 the multiplet of cooking parameters which will make it possible to control the heating means 4, as a function of the parameters entered by the user at Step 100. A regulation of the temperature inside the chamber is carried out according to said determined multiplet, which amounts to raising the ambient temperature TambM to the temperature TambMax entered according to the rate of rise contained in the multiplet . In a step 130, the control module 5 makes a comparison between the value of the internal temperature that has just been

  measured TintM and the internal temperature Tints Tints.

  If TintM is strictly lower than Tints, this indicates that the cooking parameters must be modified. In step 132, a test is then carried out on the speed of variation of TintM. This rate of variation is a function of the difference between the ambient temperature and the internal temperature and the thermal permeability of the food to be cooked. In fact, the following comparison is made: TintM (t11) - TintM (t0)> 0 C, where 0 0 is a predetermined temperature difference. The rate of rise of the internal temperature is therefore used, in this example, to control the regulation of the ambient temperature, either arbitrarily with a fixed difference of the ambient temperature with respect to the internal temperature (AT entered by the user), or thanks to the multiplet by varying the TA according to a chosen law. If the test 132 is negative, it returns directly to carry out step 120. On the other hand, if this test 132 is positive, a new test 134 is carried out to check whether the heating means are in operation. If this is not the case ("heating = 0"), we return to perform step 120. However, if this test 134 is positive ("heating = I"), we perform the following operation: TambMax - xoC, ox is a function of e. Then we return to perform step 120 to go to set the ambient temperature that has just been modified by the calculation of

3 o step 136.

  The lowering of the ambient temperature can be done naturally by stopping the heating means, or in a forced manner for example by adding, if the nature of the food allows it, a coolant in the atmosphere ( eg cold water), or by

  evacuation of part of the ambient hot air.

  As illustrated in FIG. 3, after step 136, instead of returning directly to step 120, it is possible, in a step 137, to carry out a new test so as to verify that the target ambient temperature TambMax n has not become lower than the internal temperature setpoint (or core temperature) TintMin, following the corrections made in step 136. The test 137 is therefore to check if the following condition is

filled: TintM_, <TambMax.

  If the result of this test is negative, then one proceeds, in a step 138 at the raising of the set temperature TambMax, so that one is again TintMi, <TambMax Then, one returns to step 120. In however, if the test performed in step 137 is positive, then we return

directly at step 120.

  These steps 137 and 138 make it possible to prevent the decontamination value at the periphery of the food from being not less than that of

heart (in the center of the food).

  We now resume at test level 130.

  If TintM is greater than or equal to TintM ,,, we go to step 140 to lower the ambient temperature TambM to the entered internal temperature TintMi ,, according to the rate of descent contained in the multiplet determined in step 120. step ensures that the measured ambient temperature remains slightly higher than the TintMin internal temperature to which the TintM internal temperature must be adjusted, so as to preserve the taste and nutritional qualities of the food. In other words, the following condition must be met: TintMn <

TambM <TambMax.

  In a step 150, the control module 5 determines the current decontamination value VDc, from the internal temperature measurements TintM carried out so far, and which were transmitted to it by the internal temperature sensor 7 according to a chosen frequency , for example

every half-second.

  Then, in a step 160, the control module 5 performs a test intended to verify whether the current decontamination value VDc (determined in step 150) is greater than or equal to the value of

decontamination seizure VDMi ,.

  When this condition is not met, it indicates that cooking is not complete. The control module 5 then returns

  perform steps 140 and following.

  On the other hand, when this condition is fulfilled, it indicates that the cooking is finished (step 170), and that consequently the control module 5 can stop operating the heating means 4. As a variant, the product can be maintained at an internal temperature equal to the internal temperature entered, and / or an end-of-cycle warning (or

cooking) can be issued.

  The method according to the invention may comprise a number of adaptations. Thus, steps 132 to 136 (and 137 and 138) may be omitted, the previously determined multiplet of parameters being then

adapted during a single calculation.

  Moreover, in a so-called "basic" embodiment, the device could operate without adaptation of the multiplet. In this case, the multiplet may include the maximum ambient temperature, the rate of rise to this maximum temperature, the rate of descent to the internal temperature entered, and the total duration of the cooking which ensures a decontamination value greater than or equal to that entered by the user. Once the calculated multiplet and its parameters have been set, all that remains is to wait for the end of cooking, that is to say when at the same time an internal temperature is measured substantially equal to the internal temperature. entered and a decontamination value greater than or equal to the value of

decontamination seized.

  In a slightly more sophisticated variant of the basic mode, one

  can proceed as indicated below (with reference to Figure 4).

  In a step 200, the user enters the cooking parameters Tambs, Tints and VDs. These parameters are then stored in memory 12

of the control module 5.

  In a step 210, the control module 5 determines the multiplet of cooking parameters that will make it possible to control the heating means 4 during the entire duration of the cooking, depending on the three

  parameters entered by the user in step 200.

  In a step 220, the control module 5 introduces the

  byte parameters determined in step 210 to begin cooking.

  In a step 230, the control module 5 determines the current decontamination value VDc, from the successive measurements of internal temperature TintM that are transmitted to it by the temperature probe.

  internal 7 according to a chosen frequency, for example every half

  seconds. In a step 240, which is not mandatory in the method according to the invention, the control module 5 performs a comparison test between the measured internal temperature TintM, the measured ambient temperature TambM. and the internal temperature Tints captured. It is in fact to determine permanently that the following condition is verified:

TintM <TintMin <TambM <TambM.

  This ensures that the measured ambient temperature remains slightly higher than the internal temperature Tints entered to

  which must raise the measured internal temperature TintM.

  If this test of step 240 is negative, that is to say if the measured internal temperature is greater than the measured ambient temperature, then the control module 5 proceeds, in a step 250, with an adaptation of the parameters of cooking contained in the multiplet determined in step 210 and introduced in step 220. This allows to adapt the operation of the heating means 4 to unforeseen changes in the atmosphere inside the chamber 2. Such an adaptation consists, for example, in increasing the energy radiated by the heating means 4. The step 250 forces the control module 5 to repeat the steps

220 to 240.

  When the test performed in step 240 is positive, that is to say when the measured internal temperature TintM is strictly lower than the measured ambient temperature TambM, the control module 5 performs, in a step 260, another test . It is more exactly a double test intended to determine, on the one hand, whether the decontamination value entered VDs is less than or equal to the current decontamination value VDc (determined in step 230) and, other hand if the internal temperature is entered

  s15 Tints is less than or equal to TintM measured internal temperature.

  When these two conditions are not simultaneously satisfied, this indicates that the cooking is not completed so that the module of

  command 5 repeats steps 230 and following.

  When both test conditions performed in step 260 are met, this indicates that the cooking is complete (step 270), and therefore the control module 5 can stop operating the heating means 4 or maintain the product. at a temperature equal to the entered internal temperature and / or issue an end-of-cycle warning (or

Cooking).

  The invention is not limited to the device and method embodiments described above, only by way of example, but encompasses all the variants that can be envisaged by those skilled in the art within the scope of the invention.

claims below.

  Thus, there has been described a device in which a control (adaptation) of the cooking parameters is carried out so that cooking is carried out continuously in accordance with the parameters of the multiplet. But, as indicated above, the device can operate without adaptation of

  parameters of the multiplet initially determined.

Claims (12)

  1. Cooking device, characterized in that it comprises: a receiving means (2) adapted to receive at least one food (3) and provided with heating means (4) to controlled operation, a probe of ambient temperature (6) and means (7) for determining the internal temperature of the food (3), * input means (8) arranged to allow the recording of an internal cooking temperature, a ambient cooking temperature, and a minimum decontamination value, and * a control module (5) able to determine, from the ambient and internal temperatures entered and the decontamination value entered, a multiplet of cooking parameters and operating said heating means (4) according to the parameters of said multiplet, so that the decontamination value at the end of cooking is greater than or equal to   said decontamination value entered.   2. Device according to claim 1, characterized in that said control module (5) is arranged to determine at intervals selected from the internal temperature measurements, a decontamination value in progress, to compare each decontamination value in course to the decontamination value entered and each internal temperature measured at the internal temperature entered, and to stop operating the heating means (4) when the measured internal temperature is substantially equal to the internal temperature entered and at the same time the current decontamination value is greater or equal to the value entered.   3. Device according to claim 2, characterized in that said control module (5) is also adapted to compare each internal temperature measured at the measured ambient temperature and to adapt at least some parameters of the multiplet according to the result of each comparison, so that the measured ambient temperature remains substantially greater than or equal to the internal temperature.   4. Device according to one of claims 2 and 3, characterized in   said control module (5) is arranged to determine multiplets of parameters comprising at least a maximum operating temperature associated with the entered ambient temperature, a maximum temperature rise rate and a decay rate of the operating temperature. between said maximum temperature and a   minimum temperature associated with the internal temperature entered.   5. Device according to one of claims 1 to 4, characterized in   what the decontamination value is a pasteurization value.   6. Device according to one of claims 1 to 4, characterized in   what the decontamination value is a sterilization value.   7. A method of cooking, characterized in that it comprises the following steps: a) provide a reception means adapted to receive a food and provided with controlled operation heating means, a room temperature probe and own means determining the internal temperature of the food, b) recording an internal cooking temperature, a cooking ambient temperature, and a minimum decontamination value, c) determining a multiplet of parameters as a function of the ambient and internal temperatures entered and of the decontamination value entered, and d) operating the heating means according to the parameters of the multiplet, so that the value of decontamination at the end of cooking is   greater than or equal to said decontamination value entered.   8. Method according to claim 7, characterized in that in step d) is determined at selected intervals, from the measured internal temperatures, a decontamination value in progress, then comparing each current decontamination value to the decontamination value entered and each internal temperature measured at the internal temperature entered, and the heating means are stopped from operating when the measured internal temperature is substantially equal to the internal temperature entered and at the same time the value of decontamination in progress is greater than or equal to the entered value. 9. Process according to claim 8, characterized in that in step d) each measured internal temperature is compared with the measured ambient temperature and at least some of the parameters of the multiplet are adapted according to the result of each comparison so that the measured ambient temperature remains substantially greater than or equal to   at the measured internal temperature.   10. Method according to one of claims 8 and 9, characterized in   in step c) determining a multiplet of parameters comprising at least one operating temperature associated with the ambient temperature is entered, a rise rate at the maximum temperature and a decay rate of the operating temperature between said temperature maximum and a minimum temperature associated with the internal temperature entered.   11. Method according to one of claims 7 to 10, characterized in   what the decontamination value is a pasteurization value.   12. Method according to one of claims 7 to 10, characterized in   what the decontamination value is a sterilization value.