JP2001292754A - Method and apparatus for thawing food - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thawing technique capable of thawing a frozen food uniformly in a short time. SOLUTION: This method for thawing a food is characterized by carrying out a melting process for raising the temperature of a part of the food by an external heating in at least a part of the thawing time of the food and a process for supplying a heat energy preferentially to the melted part of the food by electromagnetic radiation. This apparatus for thawing a food is characterized in that the apparatus has a first thawing means for raising the temperature of a part of the food by an external heating in at least a part of the thawing time of the food to melt a part of the food and a second thawing means for supplying a heat energy preferentially to the melted part of the food by the first thawing means by using an electromagnetic wave. Consequently, the method has extremely excellent conduction efficiency of heat energy in comparison with a conventional method by a microwave oven and can thaw the frozen food in a short time uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a food thawing technique, and more specifically, the present invention relates to a method and an apparatus for thawing frozen food in a short time and uniformly.

[0002]

2. Description of the Related Art As a method for thawing frozen foods at the time of use, there are thawing methods using hot air heating and thawing methods using a microwave oven. The conventional method using hot air heating takes a long time to transfer heat to the center of the food, and when high-temperature air is used to shorten the time, only the food surface melts and the temperature rises Had the disadvantage of doing so. On the other hand, many microwave ovens that are currently generally used for homes have adopted a rotating plate method for the purpose of uniformly heating food. However, the usual thawing method using a microwave oven has a problem that the energy absorption efficiency in the frozen part is extremely poor, and it takes too much time for the frozen part to start melting when the frozen food is thawed. In addition, when the frozen portion starts to melt, there is a problem that the portion is rapidly heated and the quality of the food is impaired. The present invention solves the above-mentioned problems, and provides a food thawing technique capable of thawing frozen foods with good heat energy conduction efficiency, in a short time and uniformly, and without heating so as to damage foods. It is intended for.

[0003]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, the temperature of a portion of food has been increased by external heating to promote melting, and the melted portion has been microwaved. The present inventors have found that the above problem can be solved by rapidly thawing with the use of, and have completed the present invention based on this finding. That is, the method for thawing food according to the present invention comprises the steps of: elevating the temperature of a part of the food by external heating and melting the food by at least part of the thawing time of the food; Is carried out. Further, the food thawing device according to the present invention,
First thawing means for increasing the temperature of a part of the food by external heating for at least a part of the thawing time of the food and melting the same, and preferentially applying heat to the melting part of the food by the first thawing means using electromagnetic waves. A second thawing means for supplying energy.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION Foods used in the present invention are various foods, vegetables, cooked rice, bento, raw fish, sashimi, meat, sushi, etc., as long as they are frozen and then thawed at the time of use. It is not limited. The food before freezing and the food after freezing or thawing may be in the form as it is, or may be in a form in which the food is not directly in contact with the surrounding environment by being packaged with an appropriate packaging material depending on the conditions of the external heating step and the like. . Packaging is performed according to the usual method, using plastic film or the like, bag-like packaging (pillow packaging, etc.), box-like packaging,
It can be in any desired form, such as wrap packaging, shrink packaging and the like. The freezing temperature of the food is not particularly limited, but is usually −
It is about 60 ° C to 0 ° C. When the present invention is applied to packaged food, it is preferable to minimize the space capacity in the food package in order to maximize the heat transfer with the outside (particularly in the external heating step), thereby further reducing the thawing time. Can be shortened.

Hereinafter, the present invention will be further described with reference to various specific embodiments. 1) The method for thawing food according to the present invention basically includes a step of raising the temperature of a part of the food by external heating for at least a part of the entire thawing time, and a method of giving priority to heat energy by electromagnetic wave irradiation to the melting part. A supplying step is performed (corresponding to claim 1 and FIG. 1). The present invention also relates to a food thawing apparatus as described below based on the above-described thawing method (corresponding to claim 2 and FIG. 1). First thawing means for increasing the temperature of a part of the food by external heating and melting it for at least a part of the thawing time of the food, and preferentially giving a part of the food melted by the first thawing means using electromagnetic waves And a second thawing means for supplying heat energy to the food (see thawing method / apparatus (A) in FIG. 1). The invention of the thawing apparatus can also be a method of thawing food, characterized by using the above-mentioned means. As the external heating in the first thawing means, any means can be used as long as it can heat-thaw the frozen portion of the food. The second thawing means only needs to be capable of irradiating electromagnetic waves, but generally uses a so-called microwave oven. In the present invention, usually as the first step, external heating is performed by the first thawing means in order to promote the melting of a part of the food. For example, 0-50
C., preferably 14 to 25 ° C., for a predetermined period of time (for example, 5 to 60 minutes) to raise the temperature of the frozen part to near the melting point over the vicinity of the center of the food, and at the same time a part of the food (usually (Outer surface part) is heated and melted beyond the melting point. After the external heat treatment, once the melting starts, the energy absorption efficiency of the electromagnetic wave is dramatically increased.
As a step, the food is rapidly thawed by electromagnetic wave irradiation (usually a microwave oven) of the second defrosting means. In addition, electromagnetic wave irradiation
The heat treatment may not necessarily be performed after the external heat treatment, and may be performed simultaneously with the heat treatment, if necessary. Specific examples related to the present invention and the results thereof are shown in Examples (Example 1) and Experimental Examples (Experimental Example 1: Simulation by computer (see FIG. 10)) described later. In the above, the energy absorption efficiency of the food frozen portion is extremely poor, and there was a problem that it took too long for the frozen portion to start melting when the frozen food was thawed, but by using the present invention as described above, The problem can be solved.

[0006] 2) One preferred embodiment of the present invention is that, in electromagnetic wave irradiation, a detected temperature of food and a set target temperature value A
And the energy supply amount of the electromagnetic wave is increased or decreased according to the deviation. The present invention includes the following thawing apparatus based on this aspect (corresponding to claim 3 and FIG. 2). In the above thawing apparatus, the second thawing means is a radiant heat sensor for detecting radiant heat generated by the food, a set target temperature storage means for storing a predetermined set target temperature, and a food temperature detected by the radiant heat sensor and a set target temperature storage. A thawing device (the thawing method shown in FIG. 2) comprising output control means for comparing the set target temperature stored value A in the means and increasing or decreasing the energy supply amount of the second thawing means according to the deviation. Device (B)
reference). The invention of the thawing apparatus can also be a method of thawing food, characterized by using the above-mentioned means. The radiant heat sensor can be constituted by, for example, a well-known non-contact infrared sensor. The set target temperature storage means is, for example, an RO mounted on a microcomputer.
M. The output control means can be constituted by, for example, a power control device based on an inverter using feedback control by a microcomputer. In this embodiment, in order to prevent food deterioration due to a rapid rise in the temperature of the melting portion near the melting point of the second stage of thawing (for example, around -5 ° C.), for example, the surface temperature of the food is observed and a predetermined level is measured. The feedback control is performed to increase or decrease the irradiation energy amount of the electromagnetic wave by the second decompression means so as not to exceed. That is, when the food surface temperature is lower than a predetermined target temperature value by a certain level difference or more (for example, 5 ° C.).
Above) is to increase the energy supply amount of the electromagnetic wave constant or in accordance with the difference, and when the difference is small (for example, less than 5 ° C.), decrease the energy supply amount in a constant manner or in accordance with the difference. Thereby, feedback control according to the difference between the temperatures can be performed. In this embodiment, for example, the temperature of the food by the radiant heat sensor is compared with the set target temperature storage value A in the set target temperature storage means, and the energy supply amount of the electromagnetic wave is changed by the output control means in accordance with the deviation. An example is shown in FIG. In the example of FIG. 16, control is performed so that an energy amount proportional to the deviation amount is supplied until the energy supply amount reaches a predetermined value. In this aspect,
The above-described feedback control can be generally performed by a microcomputer, and it is desirable that the feedback control be performed so that, for example, the surface temperature of the food does not exceed a certain level, preferably 25 ° C.

3) In another preferred embodiment of the present invention, in the external heating, the detected temperature of the food is compared with a set target temperature value A in the electromagnetic wave irradiation step or a set target temperature value B in the separately determined external heating step. The external heating supply amount is increased or decreased according to the deviation. The present invention also includes the following thawing apparatus based on this aspect (corresponding to claim 4 and FIG. 3). In the thawing apparatus of the above aspect, the first thawing means is configured such that the detected temperature of the food by the radiant heat sensor and the set target temperature storage value A in the set target temperature storage means 4 (in the electromagnetic wave irradiation step) or a separately set target temperature storage value B And a second output control means for increasing / decreasing the external heating supply amount of the first thawing means according to the deviation (in the external heating step) (see FIG. 3). How to decompress
Apparatus (C)). The invention of the thawing apparatus can also be a method of thawing food, characterized by using the above-mentioned means. The second output control means can be constituted by, for example, a heat supply amount control device using feedback control by a micro computer. In this embodiment, feedback control is performed on the external heating amount in the first stage of the thawing process. In the first external heating step using the first thawing means, the target set temperature is set relatively high because the surface of the food becomes the highest (set target temperature B: usually 10 to 50 ° C., preferably 10-30
On the other hand, in the electromagnetic wave irradiation step of the second stage using the second thawing means, the target set temperature is set low because the temperature is the highest inside the food (set target temperature A: normal freezing point ~ 40 ° C, (Preferably 0 to 20 ° C.).
In this embodiment, when the food surface temperature is lower than the predetermined target temperature value A or B by a certain level difference or more (for example, 5 ° C. or more for A, 10 ° C. or more for B), the external heating supply is constant or according to the difference. When the difference is small (for example, less than 5 ° C. for A and less than 10 ° C. for B), the temperature difference between the two is kept constant or the external heating supply amount is reduced according to the difference. Can be performed in accordance with the feedback control. In this embodiment, for example, the temperature of the food by the radiant heat sensor is compared with the set target temperature storage value A in the set target temperature storage unit, and the external heating energy supply amount is changed by the output control unit according to the deviation. An example is shown in FIG. In this example, control is performed so that an energy amount proportional to the deviation amount is supplied until the energy supply amount reaches a predetermined value. In this embodiment, the above-described feedback control can be usually performed by a microcomputer, and this feedback control allows, for example, more accurate control such that the surface temperature of the food does not exceed a certain level, preferably 25 ° C. Can be.

[0010] 4) Another preferred embodiment of the present invention is based on the lapse of time after the start of thawing, based on the set target temperature values A and / or
Alternatively, B is changed in a decreasing direction. The present invention also includes the following thawing apparatus based on this aspect (corresponding to claim 5 and FIG. 4).
In the above embodiment, based on the lapse of time after the start of thawing,
A food thawing apparatus (see thawing method / apparatus (D) in FIG. 4) characterized by having set target temperature stored value decreasing means a and / or b for changing the set target temperature stored values A and / or B. The invention of the thawing apparatus can also be a method of thawing food, characterized by using the above-mentioned means. The set target temperature storage value reduction means a and b can be configured by increasing or decreasing a control target value in feedback control by a microcomputer, for example. In this embodiment, the target temperature value A (electromagnetic wave irradiation step) is set according to the time lapse after the thawing is started by previously measuring the fluctuation relation of the external temperature of the frozen food due to the external heating or electromagnetic wave irradiation and the time lapse and managing the data. And / or change (decrease) the B value (external heating step) to an appropriate value. In this embodiment, the set target temperature values A and B are reduced by the set target temperature storage value reduction means a and b, for example, based on the lapse of time after the start of thawing, an example of which is shown in FIG.
In the example of FIG. 17, the set target value is reduced in proportion to the passage of time until the predetermined time elapses, and after the elapse of the predetermined time, feedback control is performed at a constant set target temperature value.

5) Another preferred embodiment of the present invention provides a method for thawing food, characterized in that, in external heating, fluid contact at a temperature exceeding the freezing point of the food, infrared irradiation and ultrasonic irradiation are used alone or in combination. It is an apparatus (corresponding to claim 6). Examples of the fluid include a gas such as air, carbon dioxide, and nitrogen; a liquid such as water, alcohol, and chlorofluorocarbon; and a liquid obtained by changing a liquid into a shower, and the like, which exceeds the freezing point of food (usually -5 ° C to 0 ° C). It is brought into contact with frozen food while being heated to a temperature. For example, an infrared irradiation device or the like is used as the infrared light, and an ultrasonic irradiation device or the like is used as the ultrasonic wave. The above heating means can be used alone or in combination of two or more. In the present invention, when a fluid is used as the external heating means, hot air heating of 40 ° C. or more (or other fluid heating)
Is preferably not performed, which can further reduce the thawing time. In the thawing of the first stage (first thawing means), it is most preferable to use low-temperature running water. In this case, it is necessary to completely enclose the food in a pillow package or the like so that water does not enter the package. is necessary.

6) Another preferred embodiment of the present invention is characterized in that the surface of the food is cooled with a refrigerant having a predetermined temperature or less over at least a part of the thawing time by the electromagnetic wave irradiation. The present invention also includes the following thawing device based on this aspect (corresponding to claim 7 and FIG. 5). The thawing apparatus according to the above aspect, wherein a cooling unit that cools the food surface with a refrigerant having a temperature equal to or lower than a predetermined temperature is used for at least a part of the thawing time by the second thawing unit. Thawing method / device (E)
reference). The invention of the thawing apparatus can also be a method of thawing food, characterized by using the above-mentioned means. The above-mentioned cooling means can be constituted by a refrigerant supply amount control device using feedback control by a microcomputer, for example. Conversely, during the above-mentioned feedback control, constant-temperature air, constant-temperature water, and constant-temperature carbon dioxide at a predetermined temperature or less (for example, a feedback setting value of the surface temperature or less) do not increase the surface temperature of the food during heating by electromagnetic wave irradiation. If the external cooling is performed by a gas such as carbon or nitrogen, a liquid such as alcohol or chlorofluorocarbon, or a refrigerant such as shower, a further thawing promoting effect can be obtained. Figures 11 and 12
As can be seen from the comparison, for example, by lowering the set target temperature A after the elapse of a predetermined time, in the latter half of the thawing process,
Electromagnetic energy can be supplied so that thawing proceeds effectively at the back of the food. This is because heat is taken from the food surface by the above-mentioned external cooling, whereas the electromagnetic wave energy supply means supplies energy so as to keep the food surface temperature at a predetermined temperature. This is because energy will be positively supplied to the region where: Specific examples related to this aspect and the results thereof are shown in Examples (Example 2) and Experimental Examples (Experimental Example 6: simulation by computer (see FIG. 13)) described later.

7) Another preferred embodiment of the present invention is that the cooling temperature is set based on one or a combination of a lapse of time after the start of thawing, a set target temperature value A, and a current food temperature. It is a feature. The present invention also includes the following thawing device based on this aspect (corresponding to claim 8 and FIG. 6). In the thawing apparatus of the above aspect, the refrigerant temperature of the cooling means is a lapse of time after the start of thawing,
A food thawing apparatus (thaw method and apparatus (F) shown in FIG. 6) which is set based on refrigerant temperature setting means which is set in accordance with one or more of the set target temperature storage value A and the current food temperature. )reference). The invention of the thawing apparatus can also be a method of thawing food, characterized by using the above-mentioned means. The refrigerant temperature setting means is constituted by a refrigerant supply amount control device using, for example, feedback control by a computer. The temperature of the external cooling refrigerant (low-temperature air, etc.) is one or a combination of two or more of the following: heating time elapsed by electromagnetic wave irradiation (usually microwave oven), feedback control target temperature (set target temperature value A), food surface temperature , The temperature can be controlled with even higher accuracy. For example, as the elapsed heating time becomes longer, the refrigerant temperature is increased to approach the food surface temperature, or the temperature difference between the food surface temperature and the refrigerant is set to a predetermined value (for example, 20).
By setting the refrigerant temperature to about (° C.), the temperature inside the food can be controlled with high accuracy, and the thawing speed can be promoted while preventing overheating. In the latter case, if the temperature difference is set to be smaller with the lapse of time, there is a further thawing-promoting effect. In this mode, for example, after the thawing of the outer periphery of the food material is actively promoted by external heating (for example, 25 ° C.) in the early stage of thawing, the mode is switched to external cooling (for example, 5 ° C.) to promote the thawing inside the food material. In the latter half of the thawing process, energy is supplied to the inside of the foodstuff while positively supplying energy to the inside of the foodstuff by an operation such as raising the external cooling temperature over time to approach the feedback target set temperature (for example, 25 ° C). Heating can be avoided. In this case, the elapsed time for increasing the external cooling temperature is selected according to the properties and weight of the food material.

8) In another preferred embodiment of the present invention, the set target temperature value A is determined as follows: the time elapsed after the start of thawing, the food surface temperature,
It is set based on one or a combination of a refrigerant temperature and a refrigerant temperature setting target value. The present invention also includes the following thawing device based on this aspect (corresponding to claim 9 and FIG. 7). In the thawing apparatus of the above aspect, the set target temperature storage value A in the set target temperature storage means is set to be set in accordance with one or a combination of a lapse of time after the start of thawing, a refrigerant temperature of the cooling means, and a refrigerant temperature set target value. A food thawing apparatus characterized by being set based on a target temperature storage value A setting means (see thawing method / apparatus (G) in FIG. 7). The invention of the thawing apparatus can also be a method of thawing food, characterized by using the above-mentioned means. The above-mentioned set target temperature storage value A setting means can be constituted by, for example, a ROM mounted on a microphone computer. This embodiment corresponds to the above embodiment
Contrary to 7), the feedback control target temperature set value (set target temperature storage value A) in the electromagnetic wave irradiation step is determined by comparing the temperature of the refrigerant (such as low-temperature air) with the feedback control target temperature set value (or food surface temperature). By setting the temperature difference to be a predetermined value (for example, about 20 ° C.), the same effect as in the above-described embodiment 7) can be obtained. Similarly, if the temperature difference is set so as to decrease with the lapse of time after the start of thawing, there is a further effect. In this embodiment, for example, after the thawing of the food periphery is actively promoted by external heating (for example, 25 ° C.) in the early stage of thawing, the mode is switched to external cooling (for example, 5 ° C.) to promote the thawing inside the food. According to the operation of lowering the feedback target set temperature according to the passage of time and approaching the external cooling temperature (for example, 5 ° C.), the energy supply to the inside of the food is positively performed in the latter half of the thawing process while energy is supplied to the inside of the food. Overheating can be avoided. In this case, the elapsed time for decreasing the feedback target set temperature is selected according to the properties, weight, and the like of the food material. FIG. 13 shows that after 1200 seconds elapse, the external cooling temperature is lowered and the feedback target set temperature is lowered, thereby preventing the temperature inside the food from being excessively increased.

9) In another preferred embodiment of the present invention, the amount of external heating is calculated based on the weight of the food to be thawed, whereby one of the external heating energy per hour, the external heating period and the external heating time interval is calculated. Or determining a plurality of conditions and / or calculating an electromagnetic radiation dose based on the weight of the food, thereby determining one or more conditions of irradiation energy per hour, irradiation period and irradiation time interval. It is characterized by the following. The present invention also includes the following thawing device based on this aspect (corresponding to claim 10 and FIG. 8). In the thawing apparatus of the above aspect, the weight detecting means for detecting the weight of the food to be thawed, the food weight storing means for storing the food weight detected by the weight detecting means, and the food weight stored in the food weight storing means Calculating the amount of heating by the first thawing means on the basis of the above, thereby determining one or more of the external heating energy, the external heating period and the external heating time interval per time of the first thawing means. Means for calculating the amount of heating by the second thawing means based on the food weight stored in the means for calculating the amount of heating and / or the food stored in the storage means, whereby the irradiation energy per hour, irradiation period and irradiation of the second thawing means A food thawing apparatus (see thawing method / apparatus (H) in FIG. 8) characterized by using a second thawing means heating amount calculating means for determining one or more of the time intervals. The invention of the thawing apparatus can also be a method of thawing food, characterized by using the above-mentioned means. The above-mentioned weight detecting means can be configured by, for example, attaching a strain sensor to a turntable support of a microwave oven. The food weight storage means can be constituted by, for example, a RAM mounted on a microcomputer. The first thawing unit heating amount calculation unit and the second thawing unit heating amount calculation unit can be performed by, for example, arithmetic processing using a microcomputer. Each heating time control of the first stage by the first thawing unit and the second stage by the second thawing unit is performed by controlling the weight of the frozen food (measured by a weight sensor, for example).
, The necessary and sufficient heating can be performed. In this embodiment, the relation between the weight of the frozen food and the change in the external temperature of the food (or the internal temperature) is measured in advance and the data is managed, so that the heating energy and the heating in the first and second stages are increased. It is possible to determine the period and the heating time interval to perform appropriate thawing control. In this aspect, for example, the heating amount is calculated by the heating amount calculation unit (the first thawing unit heating amount calculation unit and the second thawing unit heating amount calculation unit) based on the food weight stored in the weight storage unit, Thereby, the heating energy, the heating period, and the heating time interval are determined and controlled.

[0014] In another preferred embodiment of the present invention, the average irradiation energy per unit time irradiated at least during the thawing period by the electromagnetic wave irradiation (second thawing means) in a period other than the thawing period by the electromagnetic wave irradiation. Is also irradiated with small energy (corresponding to claim 11). This aspect is achieved by irradiating relatively weak (for example, about 1/10 times) electromagnetic waves together with external heating from the time of starting thawing, for example, during a period other than the second thawing period, that is, within the first thawing period. In addition, it is possible to increase the overheating efficiency and more accurately measure the temperature with a sensor or the like.

[0015]

EXAMPLES The present invention will be described more specifically with reference to experimental examples and examples, but the present invention is not limited thereto. [Experimental Example] Computer simulations were performed on thawing by the conventional method and thawing by the method of the present invention. This solves the heat conduction equation by the difference method,
The analysis was performed by a computer, and the results are shown in FIGS. FIG. 15 shows a partially cutaway view (a) obtained by cutting a piece into four equal parts for a substantially rectangular food material to be thawed, and a cross-sectional view (b) of one piece into upper and lower equal parts (eight equally divided food ingredients). And in the figure ~
Represents the temperature measurement position (for example, the center) of the food material. Experimental Example 1 (FIG. 10): Simulation of thawing by the method of the prior art. The experiment was performed under the condition of forced air convection at an external temperature of 25 ° C. in the apparatus. FIG. 10 shows that even at the maximum value of 7200 seconds (120 minutes) on the horizontal axis, which is the time axis, the temperature of the food center portion (the position in FIG. 16) is about −4 ° C.
Is not decompressed.

Experimental Example 2 (FIG. 11): The present invention (method 1)
3 is a simulation of thawing by the thawing method / apparatus (A) of FIG. 1. The experiment was carried out by external convection with forced air convection at a temperature of 25 ° C. inside the apparatus and feedback control at a surface temperature of 25 ° C. FIG. 11 shows that 4800 seconds (80
Min) indicates that the food was thawed.

Experimental Example 3 (FIG. 12): Simulation of thawing by the present invention (method 6), thawing method / apparatus (E) in FIG. 5). At 1200 seconds, switching from external heating 25 ° C. to 0 ° C., forced convection of air, and feedback control of surface temperature 25 ° C. were performed. FIG. 12 shows that the food was thawed in 3000 seconds (50 minutes) on the horizontal axis of time.

Experimental Example 4 (FIG. 13): The present invention (Method 6)
6 is a simulation of thawing by the thawing method / apparatus (E) in FIG. 5. Switching from external heating 25 ° C to 0 ° C at 1200 seconds, forced air convection, surface temperature 25 at 1200 seconds
This is performed under the conditions of switching from ° C. to 15 ° C. (changing the set target temperature) and feedback control. FIG. 13 shows that the food was thawed in 3900 seconds (65 minutes) on the horizontal axis of time.

Experimental Example 5 (FIG. 14): The present invention (method 6),
6 is a simulation of thawing by the thawing method / apparatus (E) in FIG. Switching from 25 ° C to 15 ° C at 2400 seconds, forced air convection, surface temperature 25 ° C at 1200 seconds →
Switching to 15 ° C. was performed under the conditions of feedback control. FIG. 14 shows a time axis of 3000 on the horizontal axis.
It shows that the food was thawed in seconds (50 minutes).

[Examples] In the following comparative examples and examples, the food material was 70 mm x 40 mm x 20 m
Prepared dishes were put on m rice, vacuum-packed with a plastic film, and frozen at -30 ° C.

[Comparative Example] As a comparison for verifying the effect of the present invention, an experiment was conducted on a conventional technique in which only external forced heating was performed. The frozen food is placed in a substantially sealed experimental device (constant temperature chamber), and the temperature in the experimental device is set at 2 ° C.
Thawed at 0 ° C. and forced convection on the food surface temperature with a fan. Then, the time until the temperature of the center of the food material reached the inside temperature of the apparatus (20 ° C.) (hereinafter referred to as “thawing time”) was measured. The measurement method is a method in which a thermocouple is inserted in the center of the food material in advance and the measurement is performed with time. From the experimental results, a thawing time of about 180 minutes was obtained. On the other hand, the simulation result corresponding to this is shown in FIG. In this method, the heat conduction equation is solved by the difference method as described above, and the analysis is performed by a computer. Although the temperature in the apparatus was set to 25 ° C. due to calculation conditions and the like,
The maximum value on the horizontal axis, which is the time axis, is 7200 seconds (120
Even in the case of (min), the temperature at the center of the food was not thawed at about −4 ° C., indicating that the result matched the measured value.

[Embodiment 1] This embodiment relates to the present invention (method 1) and the thawing method / apparatus (A) in FIG. 1).
Use warm air as the first thawing means.
After the external forced convection heating at ℃, the external heating is terminated. Thereafter, the surface temperature of the food is monitored and controlled heating is performed by a microwave oven and external cooling (room temperature) while the surface temperature does not exceed a predetermined value. Was. From the experimental results,
A thawing time of about 70 minutes was obtained (see Table 1 and FIG. 9). Thereby, the result of the comparative example which is the prior art is 18
It has been demonstrated that the ingredients can be thawed in much less than 0 minutes. On the other hand, the simulation result corresponding to this is shown in FIG. The calculation results were obtained by setting the temperature in the apparatus to 25 ° C. as in the case of the comparative example, and the thawing time was 6000 seconds (100 minutes). Although the numerical values are slightly different from the experimental results, it is considered that this is due to the difference in the setting conditions.

[Embodiment 2] This embodiment relates to the present invention (method
6), the thawing method / apparatus (E) in FIG. 5). Warm air is used as the first thawing means.
After the external forced convection heating in, the external heating ends,
Thereafter, the temperature in the apparatus was set to 0 ° C. by a cooler as a cooling means, and heating was performed by a microwave oven while forcibly cooling. From the experimental results, a thawing time of about 60 minutes was obtained (see Table 1 and FIG. 9). As a result, it was found that the food could be thawed in a shorter time than 70 minutes, which was the result of Example 1 in which the external forced heating and the microwave heating were combined. On the other hand, the corresponding simulation result is shown in FIG.
3. The calculation results were obtained by setting the temperature in the apparatus to 25 ° C. as in the case of the comparative example, and the thawing time was 4,200 seconds (70 minutes). Although it is considered that the numerical value is slightly different from the experimental result due to the difference in the setting conditions, it is shorter than the decompression time of the simulation result corresponding to the first embodiment, and it is understood that the result coincides with the tendency of the experimental result. Also, from the results of the above experimental examples and examples,
There is a correlation between the results of actual experiments and simulations, which confirms the reliability of the simulation results.

[0024] In Table 1 Ingredients center experimental results thawing completion time thawing conditions defrosting time external heating only 180 minutes external heating + microwaves 70 minutes external cooling + microwaves 60 minutes Table 1, thawing food center (position of FIG. 15) Was determined by puncturing a temperature sensor to detect a change in temperature.

[0025]

The invention has various advantages, as has been described above in a number of specific embodiments, but in particular increases the temperature of a part of the food by external heating for at least part of the thawing time of the food. By combining the step of melting and the step of supplying heat energy preferentially by irradiating electromagnetic waves to the melted part of the food, the heat energy transfer efficiency is extremely good and the short time And thawed frozen foods uniformly. In addition, the difference between the target temperature set in the external heating step (first thawing means) and the detected temperature of the food in the electromagnetic wave irradiation step (second thawing means), the elapsed time after thawing, the weight of the food, and the like. By varying the heating supply amount in both processes based on the above, feedback control of food thawing suitable for automation can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a decompression method / device (A).

FIG. 2 is a block diagram showing a configuration of a decompression method / device (B).

FIG. 3 is a block diagram showing a configuration of a decompression method / device (C).

FIG. 4 is a block diagram showing a configuration of a decompression method / device (D).

FIG. 5 is a block diagram showing the configuration of a decompression method / device (E).

FIG. 6 is a block diagram showing a configuration of a decompression method / device (F).

FIG. 7 is a block diagram showing a configuration of a decompression method / device (G).

FIG. 8 is a block diagram showing a configuration of a decompression method / device (H).

FIG. 9 is a comparative graph showing the thawing completion time of the foodstuff center.

FIG. 10 is a graph of a simulation showing thawing by a prior art method.

FIG. 11 shows the present invention (method 1);
(A) Graph of simulation showing thawing by).

FIG. 12 is the present invention (method 6);
(E) Simulation graph showing thawing by).

FIG. 13 shows the present invention (method 6), and the method and apparatus for thawing in FIG.
(E) Simulation graph showing thawing by).

FIG. 14 is a decompression method / apparatus of the present invention (method 6), FIG.
(E) Simulation graph showing thawing by).

FIG. 15 is a partially cutaway perspective view of a substantially rectangular food material to be thawed, which is obtained by cutting a piece into four equal parts, and a cross-sectional view of one piece of the upper and lower equal parts (eight equally divided food ingredients) (b).
Indicates a temperature measurement position in the food material.

FIG. 16 is a graph showing an example of the relationship between the amount of energy supply and the amount of deviation between the detected temperature of food and the set target temperature value in Invention 2) (FIG. 2).

FIG. 17 is a graph showing an example of the relationship between the set target temperature value and the elapsed time in 4) (FIG. 4) of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoto Kobayashi Kirin Engineering Co., Ltd. 1-1-25 Shinurashima-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Yuichiro Uchida 8 Yayoi-cho, Yonago, Tottori Prefecture −27 Yonego Co., Ltd. F-term (reference) 4B022 LA01 LA05 LA06 LB01 LQ02 LQ07 LQ09 LT02

Claims (11)

[Claims] 1. A method for thawing food, comprising: a step of increasing the temperature of a part of the food by external heating for at least a part of the thawing time of the food to melt the food; A method for thawing food, comprising performing a step of supplying energy. 2. A food thawing device, comprising: first thawing means for increasing the temperature of a part of the food by external heating for at least part of the thawing time of the food and melting the first food; And a second thawing means for preferentially supplying heat energy to the melted portion of the food by the thawing means. 3. A second thawing means for detecting a radiant heat generated by the food, a radiant heat sensor for storing a predetermined set target temperature, a food temperature detected by the radiant heat sensor and a set target temperature storage. 3. The defrosting apparatus according to claim 2, further comprising an output control means for comparing the set target temperature storage value A in the means and increasing or decreasing the energy supply amount of the second defrosting means according to the deviation. 4. A first thawing means for detecting a food temperature detected by a radiant heat sensor and a set target temperature storage value A for an electromagnetic wave irradiation step in a set target temperature storage means or a set target temperature storage value B for an external heating step separately determined. 4. The food defrosting apparatus according to claim 2, further comprising a second output control means for comparing the external heating supply amount of the first defrosting means according to the deviation. 5. The apparatus according to claim 3, further comprising set target temperature storage value reducing means a and / or b for changing the set target temperature storage values A and / or B based on the lapse of time after the start of thawing. Or a food thawing apparatus according to 4. 6. The food according to claim 2, wherein, in the external heating, fluid contact at a temperature exceeding the freezing point of the food, infrared irradiation and ultrasonic irradiation are used alone or in combination. Thawing device. 7. The food according to claim 5, further comprising cooling means for cooling the surface of the food with a refrigerant having a predetermined temperature or less over at least a part of the thawing time by the second thawing means. Thawing device. 8. The refrigerant temperature of the cooling means is set based on the refrigerant temperature setting means which is set according to one or a combination of a time elapsed after the start of thawing, a set target temperature storage value A and a current food temperature. The food thawing apparatus according to claim 7, characterized in that: 9. The set target temperature storage value A in the set target temperature storage means, wherein the set target temperature set in accordance with one or a combination of time elapsed after the start of thawing, the refrigerant temperature of the cooling means, and the refrigerant temperature set target value. The food defrosting apparatus according to any one of claims 2 to 8, wherein the food value is set based on a stored value A setting means. 10. A weight detecting means for detecting the weight of the food to be thawed, a food weight storing means for storing the weight of the food detected by the weight detecting means, and a food weight storing means for storing the weight of the food stored in the food weight storing means. First thawing means heating which calculates the amount of heating by the first thawing means and thereby determines one or more of the external heating energy per hour, the external heating period and the external heating time interval of the first thawing means. The amount of heating by the second thawing means is calculated based on the food weight stored in the amount calculating means and / or the storage means, whereby the irradiation energy per time, the irradiation period and the irradiation time interval of the second thawing means are calculated. The food thawing apparatus according to any one of claims 2 to 8, further comprising a second thawing means heating amount calculating means for determining one or more of the following. 11. The method according to claim 1, further comprising irradiating an energy smaller than an average irradiation energy per unit time irradiated during at least the thawing period by the second thawing means during a period other than the thawing period by the second thawing means. And
The food thawing apparatus according to any one of claims 2 to 10.