EP0000959B1 - Méthode pour cuire des morceaux de viande peu epais dans un four à micro-ontes - Google Patents

Méthode pour cuire des morceaux de viande peu epais dans un four à micro-ontes Download PDF

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Publication number
EP0000959B1
EP0000959B1 EP19780100793 EP78100793A EP0000959B1 EP 0000959 B1 EP0000959 B1 EP 0000959B1 EP 19780100793 EP19780100793 EP 19780100793 EP 78100793 A EP78100793 A EP 78100793A EP 0000959 B1 EP0000959 B1 EP 0000959B1
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EP
European Patent Office
Prior art keywords
humidity
time
microwave oven
characteristic
temperature
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Expired
Application number
EP19780100793
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German (de)
English (en)
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EP0000959A1 (fr
Inventor
Ronald G. Buck
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Northrop Grumman Guidance and Electronics Co Inc
Original Assignee
Litton Systems Inc
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/6447—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors
    • H05B6/6458—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors using humidity or vapor sensors
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D22/00—Control of humidity
    • G05D22/02—Control of humidity characterised by the use of electric means
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/6447—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors
    • H05B6/645—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors using temperature sensors

Definitions

  • This invention relates to a method of cooking thin meat bodies in a microwave oven.
  • Another current prior art device 'for measuring the internal temperature of meats being cooked is to insert a temperature probe into the meat while in the microwave oven heating cavity which connects to the control circuitry of the microwave oven. While the temperature probe is accurate in indicating the temperature of the meat being cooked by microwave energy, the probe only senses the temperature of the immediate area surrounding the probe and does not take into account the equilibrium state of the internal temperature of the meat. If the temperature of the meat is not uniform and the probe is placed at a hot spot in the meat, the readings from the temperature probe are not indicative of the internal doneness of the meat.
  • the probe which is inserted into the meat is cumbersome and bulky for the cook who is trying to monitor the internal doneness of the meat during the microwave cooking in the microwave oven heating cavity.
  • a temperature probe For a thin piece of meat being approximately equal to or less than one wavelength, it is difficult for a cook, if not impossible, to insert a temperature probe into the meat as the thickness is approximately no greater than one centimeter.
  • DE - OS 2 706 367 describes a method for determining the time at which the energy source of a microwave oven is to be switched off in order to get a foodstuff done to a predetermined value.
  • the humidity is measured to detect a characteristic increase in humidity during cooking time.
  • the present invention obviates the foregoing disadvantages of the prior art by providing a method of cooking thin meat bodies in a microwave oven and determining the accurate switch-off time.
  • the present invention provides for a method for cooking thin meat bodies in a microwave oven wherein the time dependent "in-situ” humidity and temperature environmental conditions of a microwave oven heating cavity are sensed and sampled, the absolute humidity is determined from the sampled "in-situ” humidity and temperature, the absolute humidity is determined at a plurality of points on a "characteristic humidity curve”, and the temperature of the meat is determined from the slope of the sampled points of the "characteristic humidity curve".
  • a significant aspect and feature of the present invention is that the claimed method provides for the determination of the temperature of a thin meat body being cooked in the microwave oven. Since the meat is thin, that is being approximately equal to or less than one skin depth which for 2450 megahertz is one centimeter, the surface temperature of the meat is equal to the internal temperature of the meat.
  • Another advantage of the invention is the determination when the thin piece of meat is cooked to doneness by sensing the dependent "in-situ” humidity and the temperature environmental conditions of the microwave oven heating cavity.
  • the term "in-situ” as used in this application is defined as the actual time dependent environmental conditions which exist in the environment surrounding the thin meat which is located in and cooked in the microwave oven heating cavity.
  • a humidity sensor and temperature sensor may be positioned outside of the microwave oven heating cavity, the sensors are configured to sense the "in-situ” environmental conditions of the microwave oven heating cavity and provide "in-situ” signal information of the environmental conditions of the microwave oven heating cavity to a programmable controller controlling the microwave oven.
  • Figure 1 illustrates a flow chart 10 of the method of cooking thin meat in accordance with the present invention.
  • the flow chart provides for the solving of the equation where equation 1 is a "characteristic humidity curve" for thin meat having a thickness approximately equal to or less than one skin depth.
  • h o is the ambient absolute humidity
  • h x is the peak absolute humidity
  • B is a coefficient, characteristic of meats having units of 1/seconds 2.
  • the flow chart 10 starts at 12 where the "in-situ” relative humidity of the microwave oven heating cavity is sampled and stored 14, the "in-situ” temperature of the microwave oven heating cavity is sampled and stored 16, the saturated humidity 18 is determined, and the absolute humidity 20 is determined from the multiplication of the relative humidity times the saturated humidity.
  • the program after waiting K seconds 22, then sets n equal to 1 at 24 and initiates by sampling data 26 at four points to compute the slope of the "characteristic humidity curve" for the algorithm of equation 1 for the method. Until n equals five 28 condition is satisfied, n is incremented by one 30 waiting m seconds 32 between each sample. Data 26 is sampled at four points satisfying conditions 28 and 30 waiting m seconds 32 between each sample. When n equals five 28 condition occurs, the slope 34 is determined by solving the simultaneous equations 36 for h x and B.
  • t x is determined 38 and t done is equal to a percentage of t x 40 as the "characteristic humidity curve" proceeds to infinity and a cook is only interested in the plateau of the "characteristic humidity curve”.
  • t real less than or equal to t done YES condition 42 exists, then the program recycles itself after waiting K seconds to again begin sampling data at four points to determine the slope 34, solve for t x , etc. This continues to repeat until a t real equal to or less than t done NO condition 42 occurs at which time the microwave oven is turned off 46 and a done indication is given to the cook.
  • the method of cooking thin meat in a microwave oven is premised on the sensing concept based on the most fundamental cooking principles. That is, as microwave energy is converted to thermal energy, the internal temperature of the meat increases. As the internal temperature of the meat increases, some of the thermal energy is used to break the bonding forces holding the water molecules to the food's cell structure. When the latent heat of vaporization has been added to the food, these free water molecules are vaporized and released locally. Thus, the rate of evaporation is directly proportional to the rate of temperature rise. By monitoring time dependent "in-situ" environmental conditions of the microwave oven heating cavity with sensors, the meat's internal temperature, and surface temperature for a thin piece of meat being approximately less than or equal to one skin depth, are determined.
  • the "characteristic humidity curve" 48 of absolute humidity in grams per cubic meter versus cooking time in seconds of Figure 2 for the thin meat equation 1 is determined by sensing the time dependent "in-situ” humidity and temperature environmental conditions of the microwave oven heating cavity during microwave cooking of thin meats.
  • the time dependent "in-situ” environmental conditions are defined as the sensed humidity and temperature of the microwave oven heating cavity by humidity and temperature sensors.
  • Each particular cut of thin meat has its own particular "characteristic humidity curve". he is the initial absolute humidity and h x is the peak absolute humidity at the time t x of the "characteristic humidity curve" 48.
  • Figure 2 depicts a characteristic humidity curve derived from a plot of absolute humidity versus elapsed cooking time. The changes in slope of the curve are indicative of the rate of evaporative water loss from the thin meat body effecting the absolute humidity in the cooking cavity.
  • the point of peak absolute humidity, h x indicated at 60, is or primary interest.
  • the "characteristic humidity curve" 48 plateaus at point 60 indicating that surface temperature of the meat has reached equilibrium at one hundred degrees centigrade.
  • the internal temperature is approximately and for all practical considerations, the same as the surface temperature from equation 1 for any point of the "characteristic humidity curve" of Figure 2.
  • h x and B are computed by solving simultaneous equation 36 to predict when the one hundred degree centigrade point 60 occurs.
  • the temperature is assumed linear between he and one hundred degrees centigrade so that once t x is computed, the corresponding time for any other temperature may be computed such as to determine when t done is reached.
  • the method may be implemented in accordance with the flow chart 10 of Figure 1 as an algorithm stored in a programmable controller such as an ltel 8080 Microprocessor in the microwave oven.
  • This algorithm of Figure 1 determines the temperature for a thin piece of meat for any point on the "characteristic humidity curve" of Figure 2.
  • An aluminium oxide humidity sensor such as a Thunder Scientific TC-2000 Humidity Measurement Module, and a temperature sensor, such as a National Semiconductor Corporation LX 5700 Temperature Transducer, are positioned adjacent to and by the exit ventilation port to the exterior side of the microwave oven heating cavity for way of example and for purposes of illustration only to sense the time dependent "in-situ" environment conditions of the microwave oven heating cavity.
  • the sensors can be positioned anywhere as long as the time dependent "in-situ" environmental conditions of the microwave oven heating cavity are sensed and the sensors are electromagnetically protected from the microwave oven heating cavity.
  • the humidity sensor and the temperature sensor connect to the programmable controller having the steps of the algorithm of Figure 1 stored in the memory of the programmable controller.
  • the programmable controller connects to control the microwave power source power supply and the air exchange circuit and turns the oven off when a NO condition exists at the t reel is less than or equal to a predetermined t done decision point 42.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Control Of High-Frequency Heating Circuits (AREA)
  • Electric Ovens (AREA)

Claims (7)

1. Méthode pour cuire un aliment dans un four à hyperfréquences, comprenant un capteur de mesure de l'humidité de l'environnement d'une cavité de cuisson du four à hyperfréquences pendant le temps de cuisson, détectant la pente de la courbe humidité-temps et calculant l'instant d'arrêt à partir de l'apparition d'une montée caractéristique de la courbe humidité temps, et arrêtant la source d'énergie au temps calculé de cuisson à point, caractérisée par les étapes suivantes, dans lesquelles une mince pièce de viande est utilisée comme aliment, et qui consistent:
(a) à mesurer l'humidité à plusieurs intervalles expacés dans le temps et mémoriser ces mesures;
(b) à calculer la pente de la courbe humidité-temps à partir des mesures obtenues dans l'étape (a);
(c) à comparer la pente calculée avec la pente d'une courbe caractéristique humidité-temps et à calculer, à partir du résulat de ladite comparaison, le temps mis par l'aliment pour atteindre l'équilibre thermique à la température d'ébullition de l'eau, et
(d) à calculer le temps mis par la pièce de viande pour atteindre un degré de cuisson présélectionné en fonction du temps d'équilibre thermique.
2. Méthode de la revendication 1, caractérisée en ce que, pour mesurer l'humidité de l'environnement de la cavité de cuisson du four à hyperfréquences, deux capteurs sont utilisés, détectant l'humidite relative et la température de l'environnement de la cavité, respectivement, et en ce que l'étape de mesure d'humidité comprend le calcul de l'humidité absolue dudit environnement de la cavité à partir de l'humidité relative détectée dudit environnement de la cavité et de la température.
3. Méthode de la revendication 1 ou 2, caractérisée en ce que la courbe caractéristique humidité-temps est décrite par l'équation:
Figure imgb0003
dans laquelle:
h" = humidité absolue à l'intervalle de temps N,
ho = humidité absolue à l'intervalle de temps N = 0,
hx = humidité absolue de pointe à l'équilibre thermique,
B = un coefficient, caractéristique de ladite pièce mince de viande.
4. Méthode de l'une des revendications 1-3, caractérisée en ce que l'équation de la courbe caractéristique humidité-temps est mémorisée dans un microprocesseur.
5. Méthode de l'une des revendications 1-4 dans laquelle ledit temps calculé de cuisson à point est calculé sous la forme d'un pourcentage présélectionné du temps d'équilibre thermique.
6. Méthode de la revendication 5, caractérisée en ce que le pourcentage présélectionné du temps d'équilibre thermique est mémorisé dans le microprocesseur.
7. Méthode de l'une des revendications 1-6, caractérisée par des étapes (a) à (d) répétées en cycles successifs et dans laquelle le temps calculé de cuisson à point est mis à jour dans chaque cycle.
EP19780100793 1977-08-30 1978-08-30 Méthode pour cuire des morceaux de viande peu epais dans un four à micro-ontes Expired EP0000959B1 (fr)

Applications Claiming Priority (2)

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US82907577A 1977-08-30 1977-08-30
US829075 1977-08-30

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EP0000959A1 EP0000959A1 (fr) 1979-03-07
EP0000959B1 true EP0000959B1 (fr) 1981-09-30

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AU (1) AU520661B2 (fr)
CA (1) CA1104213A (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5613692A (en) * 1979-07-11 1981-02-10 Matsushita Electric Ind Co Ltd High frequency heater
DE3066593D1 (en) * 1979-08-17 1984-03-22 Matsushita Electric Ind Co Ltd Heating apparatus with sensor
JPS5880426A (ja) * 1981-11-06 1983-05-14 Matsushita Electric Ind Co Ltd 高周波加熱装置
WO2014102746A1 (fr) * 2012-12-27 2014-07-03 Koninklijke Philips N.V. Appareil et procédé de détermination de la température à cœur de produits alimentaires
CN104919891B (zh) * 2012-12-27 2018-07-06 皇家飞利浦有限公司 用于确定食物的芯部温度的装置和方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1090798B (de) * 1958-10-14 1960-10-13 Siemens Elektrogeraete Gmbh Hochfrequenz-Strahlungsherd
US3654417A (en) * 1970-10-30 1972-04-04 Litton Precision Prod Inc Microwave oven including air flow system
US4011428A (en) * 1975-03-24 1977-03-08 Essex International, Inc. Microwave oven timer and control circuit
GB1545918A (en) * 1975-05-20 1979-05-16 Matsushita Electric Ind Co Ltd Apparatus for controlling heating time utilising humidity sensing
GB1539296A (en) * 1976-02-17 1979-01-31 Matsushita Electric Ind Co Ltd Heating control apparatus by humidity detection

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AU3930678A (en) 1980-03-06
EP0000959A1 (fr) 1979-03-07
AU520661B2 (en) 1982-02-18
CA1104213A (fr) 1981-06-30

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