DE102018111789A1 - Process for low-temperature cooking of foodstuffs - Google Patents

Abstract

The invention relates to a method for low-temperature cooking of foods by means of the following steps: the food to be cooked is introduced into a cooking space, wherein at least one cooking time-relevant parameter is detected, a control module calculates a temperature profile of a cooking process on the basis of the parameter relevant to the cooking time, containing a cooking phase and a pasteurization phase, wherein a predetermined maximum duration of the cooking phase is observed, - the food is cooked with the calculated temperature profile, - a user is informed that the cooking process is completed.

Description

The invention relates to a method for low-temperature food cooking.

It is well known that foods can be cooked at low temperatures, that is, at temperatures slightly above the target core temperature of the finished cooked food. Such methods are very gentle on the food and lead to a sensory very high-quality food.

A disadvantage of low-temperature cooking, however, is that the finished cooked food is not optimal under aspects of food safety. Unlike foods that are cooked at very high temperatures, cooked or cooked in superheated steam, any germs in low-temperature cooking may not be completely killed. Although certain important germs are already killed at 49 ° C, but not all. In addition, for a sufficient activation of the nuclei, a very long retention time is needed. Therefore, low-temperature cooked foods are not safe for at-risk populations (such as elderly or sick people and children). In addition, low-temperature foods are often only short-lived.

The object of the invention is to provide a method for low-temperature cooking of foods, with which the food can also be cooked in commercial applications (for example in restaurants, canteens and large catering) so that they are flawless in terms of food safety , are longer lasting and still have a high sensory quality.

• - das zu garende Nahrungsmittel wird in einen Garraum eingebracht, wobei mindestens ein garzeitrelevanter Parameter erfasst wird,
• - ein Steuermodul errechnet auf der Basis des garzeitrelevanten Parameters einen Temperaturverlauf eines Garprozesses, der eine Garphase und eine Pasteurisationsphase enthält, wobei eine vorgegebene Maximaldauer der Garphase eingehalten wird,
• - das Nahrungsmittel wird mit dem errechneten Temperaturverlauf gegart,
• - ein Benutzer wird darüber informiert, dass der Garprozess abgeschlossen ist.

To achieve this object, the following steps are provided according to the invention in a method for low-temperature cooking of foods:

• the food to be cooked is introduced into a cooking space, whereby at least one cooking time-relevant parameter is detected,
• a control module calculates, on the basis of the parameter relevant to the cooking time, a temperature profile of a cooking process which contains a cooking phase and a pasteurization phase, wherein a predetermined maximum duration of the cooking phase is maintained,
• - the food is cooked with the calculated temperature curve,
• a user is informed that the cooking process is completed.

The method according to the invention combines two measures to obtain, during low-temperature cooking, a food which is impeccable from a food-technical point of view. On the one hand, a maximum duration of the cooking phase is specified. The cooking phase is particularly critical in terms of food safety as the food passes through a critical temperature range during cooking, during which most of the germination occurs. According to the invention it is ensured that the cooking phase does not last longer than can be tolerated taking into account the requirements of food safety. On the other hand, according to the invention, a pasteurization phase is provided, with which possible germs are reduced to such an extent that the food is safe even for risk groups and can be stored for a certain period of time. In this case, the knowledge is used that a longer holding time, even at relatively low temperatures, leads to germs being killed.

According to one embodiment of the invention, it is provided that the control module calculates a minimum duration of the pasteurization phase. This minimum duration may depend on the food being cooked, as well as the core temperature that the cooked food has.

The cooking time relevant parameter that is used for the calculation of the temperature profile of the cooking process can be in particular the diameter of the food, the size and / or the geometric shape. These are, in particular, those parameters which are relevant with regard to the heat conduction when a given core temperature in the middle is reached for a certain foodstuff.

The possible cooking time-relevant parameters can be classified into groups, whereby the acquired cooking time-relevant parameter is classified in one of the groups. This reduces the effort in calculating the temperature profile of the cooking process. The geometric shape of the food can be assigned, for example, the groups plate, cylinder or ball, in which case is placed in particular on the cross section of the food to be cooked. For example, in terms of the thickness of the food, the different groups may represent a distinction between small, medium and large.

According to one embodiment of the invention, the duration of the cooking phase is determined using the following formula: $$\text{t}=\text{a}*\text{In}\left(\text{GT}-{\text{T}}_0\right)*{\left(\text{bx}\right)}^2$$

• t: Garzeit [Minuten]
• a: empirisch ermittelter Faktor der Garzeit pro Temperaturdifferenz und Fläche [s/(ln(°C) * cm²] Dieser Faktor ist abhängig von der Temperaturdifferenz zwischen der Garraumtemperatur und der Soll-Kerntemperatur und dem Verhältnis aus Breite und Dicke (B/D) des zu garenden Nahrungsmittels. Dieser Faktor wird für die einzelnen Produktgruppen definiert.
• GT: Garraumtemperatur [°C] In der Regel beträgt GT gleich der Soll-Kerntemperatur plus 2 °C. Diese Differenz zwischen der Garraumtemperatur und der Soll-Kerntemperatur kann dann höher gewählt werden, wenn andernfalls nicht innerhalb der vorgegebenen Maximaldauer die Soll-Kerntemperatur erreicht werden kann.
• T₀: Ausgangstemperatur [°C] Hier kann aus Gründen der Vereinfachung stets von T₀ gleich 0 °C ausgegangen werden.
• b: empirisch ermittelter Faktor, der repräsentativ für die Formänderung des zu garenden Nahrungsmittels während des Garprozesses ist. Er ist abhängig von der Soll-Kerntemperatur und von der Produktkategorie, da sich manche Lebensmittel (insbesondere Fleischsorten) mehr verändern als andere. Dieser Faktor wird insbesondere bei im Ganzen gegartem Roastbeef benötigt, das auf eine Kerntemperatur größer 60 °C gegart werden soll.
• x: charakteristische Länge, also kürzeste Strecke zum Schwerpunkt des Produkts. Bei einem zylindrischen oder kugelförmigen Nahrungsmittel entspricht x der halben Dicke oder des halben Durchmessers; bei einem quaderförmigen Produkt entspricht x der Hälfte der Dicke.

Here are:

• t: cooking time [minutes]
• a: empirically determined factor of the cooking time per temperature difference and area [s / (ln (° C) * cm ² ] This factor depends on the temperature difference between the oven temperature and the nominal core temperature and the ratio of width and thickness (B / D ) of the food to be cooked This factor is defined for the individual product groups.
• GT: cooking chamber temperature [° C] GT is usually equal to the nominal core temperature plus 2 ° C. This difference between the cooking chamber temperature and the desired core temperature can then be selected higher, if otherwise not within the predetermined maximum duration, the desired core temperature can be achieved.
• T ₀ : starting temperature [° C] Here, for reasons of simplification, it can always be assumed that T ₀ equals 0 ° C.
• b: empirically determined factor that is representative of the change in shape of the food to be cooked during the cooking process. It depends on the target core temperature and the product category, as some foods (especially meats) change more than others. This factor is particularly needed for roast beef cooked in the whole, which should be cooked to a core temperature greater than 60 ° C.
• x: characteristic length, ie the shortest distance to the center of gravity of the product. For a cylindrical or spherical food, x is half the thickness or half the diameter; in the case of a cuboid product, x is equal to half the thickness.

The inventive method uses a maximum temperature during the cooking phase, which is not higher than 90 ° C. The lower the maximum temperature during the cooking phase, the higher the quality of the cooked food. It is therefore advantageous that the maximum temperature is not more than 20 ° C above the target core temperature. It is optimal that the maximum temperature during the cooking phase is no more than 2 ° C above the set core temperature. In this case, it is always assumed that with the selected cooking chamber temperature, the predetermined maximum duration of the cooking phase is maintained, ie the target core temperature is reached before the predetermined maximum duration is reached.

The predetermined maximum duration is 4 hours according to an advantageous embodiment of the method according to the invention. This value is advantageous and generally accepted in terms of food safety.

According to an advantageous embodiment of the invention, the food is cooked in a steam atmosphere. This has the advantage that there is a high heat input into the food. As a result, the cooking phase can be kept as short as possible. On the other hand, a steam atmosphere has the advantage that the food does not dry out during the pasteurization phase.

According to one embodiment of the invention, it is provided that the parameter relevant to the cooking time is determined by means of a camera and an image evaluation module. This prevents incorrect operation. According to the invention, it can also be provided that the parameter relevant to the cooking time is queried by means of a user interface. This can either be done in addition to the detection by means of camera and image evaluation module, for example, if an automated assignment is not possible with the desired security, or only if the effort for the camera and the image evaluation module should be avoided.

• - 1 schematisch ein Gargerät, das beim erfindungsgemäßen Verfahren verwendet wird;
• - 2 in einem schematischen Diagramm den Verlauf der Garraumtemperatur und der Kerntemperatur bei einem ersten Ausführungsbeispiel; und
• - 3 in einem schematischen Diagramm den Verlauf der Garraumtemperatur und der Kerntemperatur in einem zweiten Ausführungsbeispiel.

The invention will be explained below with reference to exemplary embodiments which are illustrated in the attached drawings. In these shows:

• - 1 schematically a cooking appliance, which is used in the method according to the invention;
• - 2 in a schematic diagram, the course of the cooking chamber temperature and the core temperature in a first embodiment; and
• - 3 in a schematic diagram, the course of the cooking chamber temperature and the core temperature in a second embodiment.

In 1 is schematically a cooking appliance 10 shown, with which the inventive method can be performed. This is a cooking appliance for professional use, especially for restaurants, canteens and large catering.

The cooking appliance has a cooking chamber 12 on in which food can be cooked. As an example, here is a food 14 shown, which is roast beef.

In the oven 12 For example, the foodstuffs can be cooked in a cooking chamber atmosphere, which is characterized in particular by the temperature and the humidity. To set these parameters, instructs the cooking appliance 10 a heater 16 as well as a steam generator 18 on. These are from a control device 20 driven.

The control device 20 also controls the drive motor 22 a fan wheel 24 on, with which the circulation speed of the cooking chamber atmosphere in the cooking chamber 12 can be controlled.

The cooking appliance 10 also has a device 26 for detecting at least one food time relevant parameter of the food. This is a camera. The camera 26 is with the control device 20 in connection. In the control device 20 is a control module 28 integrated, which can calculate a temperature profile of a cooking process on the basis of the cooking time relevant parameter.

The cooking appliance 10 also has a user interface 30 on, for example, a touch-sensitive screen, with which an operator can select a cooking process or can also enter cooking time-relevant parameters directly.

In the following, suppose that the piece of roast beef 14 in the oven 12 is introduced and cooked there in a low-temperature cooking process.

When introducing the roast beef 14 in the cooking chamber, the size and shape of the piece of meat are detected. Based on this, the control module calculates the temperature profile of the piece of roast beef 14 should be cooked best.

It is assumed that a target core temperature of 57 ° C should be achieved. The control module calculates, for example, using the formula given above, that at a cooking chamber temperature of 59 ° C, the desired target core temperature is achieved with a cooking phase, which is completed at time t ₁ , wherein the cooking phase lasts 3.5 hours. This duration is below a predetermined maximum duration, in the control device 20 with 4 hours is deposited.

The diagram shows the course of the oven temperature with the solid line and the course of the core temperature in the roast beef 14 shown with the dashed line.

When the cooking phase is completed, a pasteurization phase starts, during which the core temperature remains essentially unchanged, since the cooking chamber temperature is reduced on average to the desired core temperature. The pasteurization phase serves to reduce the burden of any germs present. The duration of the pasteurization phase can be calculated, for example, according to the P-value method.

When the pre-calculated pasteurization time has expired (here at time t ₂ ), a user is notified that the food is now ready cooked.

In 3 an embodiment is shown in which the control module 28 recognizes that when using a cooking chamber temperature that is only slightly above the set core temperature, the cooking phase would exceed the stored maximum duration. This may be due in particular to the fact that the roast beef 14 has too large a diameter. Therefore, a cooking chamber temperature is selected for the cooking phase, which is here by 10 ° C higher than in 2 shown embodiment. This ensures that the core temperature of the roast beef 14 at a time t ₁ , which is a maximum of 4 hours after the start of the cooking process, has reached the desired value of 57 ° C. The cooking phase is followed by a pasteurization phase, during which the cooking space temperature is lowered to 57 ° C., so that the core temperature does not increase any more, or at least insignificantly.

Again, the operator is notified as soon as the pasteurization phase is complete.

Claims (10)

Process for low-temperature food cooking using the following steps: the food to be cooked is introduced into a cooking space, whereby at least one cooking time-relevant parameter is detected, a control module calculates, on the basis of the parameter relevant to the cooking time, a temperature profile of a cooking process which contains a cooking phase and a pasteurization phase, wherein a predetermined maximum duration of the cooking phase is observed, - the food is cooked with the calculated temperature curve, a user is informed that the cooking process has been completed. Method according to Claim 1 , characterized in that the control module calculates a minimum duration of the pasteurization phase. Method according to Claim 1 or Claim 2 , characterized in that the cooking time relevant parameter is the diameter, the size and / or the geometric shape. Method according to Claim 3 , characterized in that possible cooking time relevant parameters are arranged in groups and that the detected cooking time relevant parameter is classified in one of the groups. Method according to one of the preceding claims, characterized in that the duration of the cooking phase is determined by the following formula: $$\text{t}=\text{a}*\text{In}\left(\text{GT}-{\text{T}}_0\right)*{\left(\text{bx}\right)}^2$$

Method according to one of the preceding claims, characterized in that the maximum temperature during the cooking phase is not higher than 90 ° C. Method according to Claim 6 , characterized in that the maximum temperature during the cooking phase is not more than 20 ° C above the target core temperature is selected so as not to exceed the maximum duration of the cooking phase. Method according to Claim 7 , characterized in that the maximum temperature during the cooking phase is selected by not more than 3 ° C and in particular not more than 2 ° C above the target core temperature, if with the resulting duration of the cooking phase whose predetermined maximum duration is not exceeded. Method according to one of the preceding claims, characterized in that the cooking time-relevant parameter is determined by means of a camera and an image evaluation module. Method according to one of the preceding claims, characterized in that the cooking time-relevant parameter is queried by means of a user interface.

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