JPS6057816B2 - Thawing and thawing/reheating cooking methods using combined heating of food - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new method for most effectively defrosting or defrosting and reheating various frozen foods or cooked frozen foods.

There are many types of frozen foods, but they can be broadly divided into fried foods and oil-based foods that are dry and suitable for open heating, rice dishes that are often used in Japanese cuisine, and sushi foods such as steamed sushi and chirashi sushi. Fully cooked frozen foods with high moisture content, such as rice bowls, simmered dishes, hot pot dishes, and stews, and cases where browning is required during the finishing process, such as grilled fish and grilled meat. When it comes to fully cooked frozen foods, such as those that need to be thawed and reheated and eaten at the right temperature all at once, and on the other hand, when it comes to frozen foods such as meat, fresh seafood, and meat, fresh frozen foods can be kept fresh by simply thawing them. , can be broadly classified according to its use as food with good flavor.

However, the above types differ in their ingredients, composition, moisture content, flavor conditions (texture) aroma, suitable eating temperature, packaging, etc., so if a uniform thawing or thawing/reheating method is used, It is clear that the results are suitable for some frozen foods but not for others. Conventionally, methods of thawing or thawing and reheating according to the type of frozen food and its conditions have been used, for example, in "Theory and Application of Food Freezing," Vol. Published by Shoin Publishing, pages 290-304, and is currently in use.

The one described in the above publication is a so-called single heating method, and therefore, in order to respond to the types and conditions of frozen foods, it is necessary to prepare many types of each heating method. Of course, it is practically impossible to prepare these in places such as restaurants and homes that handle many menus. Therefore, as a step forward to solve this problem, a composite heating means consisting of only two heating devices such as microwave and convection (hot air), microwave and infrared rays (heater), and infrared rays and steam is provided. It came to this. For example, there is Japanese Patent Publication No. 37-13733 on combined heating of microwave and convection, and microwave and infrared rays (
U.S. Patent No. 3,569,656 for combined heating of
There is a number specification.

The former uses high frequency energy (microwaves) for frozen foods.
This method uses both hot air and hot air at the same time to thaw frozen foods, but it has the following drawbacks. In other words, Table 1 below shows the relationship between freezing temperature and the amount of freezing water in food (Kato, 1965).
In the following, unfrozen water is contained in the frozen food, and the high frequency energy does not act on the ice, but as a result of acting on the unfrozen water, the area heats up and becomes high temperature.

For example, when high-frequency energy and hot air are applied to the beef in the above table at the same time, the corners and unfrozen parts of the beef surface absorb significantly more high-frequency energy, that is, microwaves, resulting in overheating and high temperature. As the surface thaws rapidly and is heated by hot air,
Both of these causes heating to occur at an increasingly accelerated rate. Therefore, after thawing, the corners and surface layer are already cooked, resulting in uneven thawing on the surface and inside, and the overall appearance is extremely poor. This results in homogeneous thawing. Later, to solve this problem, a cold air unit was attached to this type of equipment to circulate cold air at -15℃ during thawing to reduce local overheating on the surface and corners and achieve uniform thawing. The cost of installing a cold air unit is that much more expensive. Furthermore, there are heating methods and frozen foods in which cold air becomes an obstacle to thawing, which has been considered a problem. on the other hand,
The latter method uses microwaves and a heater in combination, and a thawing method has also been proposed as one example.

This is done by raising the temperature of the oven to a certain level in advance, and then setting the defrosting program on a timer so that the microwave and heater work simultaneously or alternately within the selected cycle time required for defrosting. This method diffuses heat during the downtime, and can be evaluated as being a step ahead of the former method. However, even in this case, the phenomenon of local overheating of the food surface and corners cannot be avoided, as in the previous case. Therefore, returning to the original point, it is conceivable to use only effective heating means other than microwaves (high frequency energy) in the thawing process, and to use microwaves or other heating means alone or in combination in the reheating and cooking process after thawing.

This method has the advantage that it is possible to prevent the disadvantages of microwaves in the thawing process, and to avoid wasting electricity costs during the early to middle stages of thawing, which are not effective for thawing. However, the following new problem arises. In general, if the freezing speed is accelerated during freezing, the maximum ice crystal formation zone (-5°C to 0°C) is quickly passed through and fine ice crystals are formed, which can prevent damage to food tissues and protein denaturation. Are known. In other words, if thawing progresses slowly, -5℃
to 0°C for a long time, which promotes the growth of ice crystals and denaturation of proteins, and this drawback cannot be avoided with the above method. As described above, the conventional thawing or thawing-reheating methods involve various problems, and as there is still no suitable thawing method, this has been a major bottleneck in the widespread use of frozen foods.

In view of the above-mentioned conventional problems, the present invention was developed as a result of intensive research.
The present invention has been made, and its gist is to provide multiple types of dithermal conduction heating means, such as generating devices for dry hot air, moist hot air, heated steam, etc., provided in the refrigerator, and hot water immersion devices. The food is first thawed by heat treatment using the dithermal conduction heating means selected by operating the operating means according to the type of frozen food and its conditions, and then The present invention is characterized in that the food is subjected to a compound heating treatment by a cooperative combination of a conductive heating means and a dielectric internal heating means to perform secondary defrosting or defrosting and reheating cooking.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to FIGS. 1 to 3, which illustrate the apparatus used in the invention. In the figure, 1 is a box-shaped main body, and a food loading port 3 having a door 2 that can be opened and closed is provided on the front of the main body.

Rotating shafts 4, 4 are disposed above and below within the main body 1, sprockets 5 are fixedly installed at both ends of each shaft 4, 4, and an endless chain 6 is hung on the sprocket 5. Both ends of a basket-shaped food tray 8 are suspended by using arms 7 provided outward at intervals, and are always held horizontally. 9 is a drive motor provided outside the main body 1, and a reduction gear 10
The upper shaft 4 is driven through the chain 11 and the chain 6.
There are two cases: low-speed continuous operation and -pitch intermittent rotation.

Reference numeral 12 denotes a water storage section provided in the lower part of the main body, and a hot water conduit 13 is connected to the bottom of one end thereof, and the end of this pipe 13 is connected to the bottom of a heat exchanger 14 at the other end of the main body 1.

A large number of sheathed heaters 15 are provided in the exchanger 14, and two levels of water level detectors 16 and 17 are provided, upper and lower.
The solenoid valve 19 in the middle of the water supply pipe 18 to the water storage section 12 is controlled by the detectors 16 and 17 to ensure that water is appropriately stored in the water storage section 12 and only in the lower part of the heat exchanger 14 of the conduit 13. It is possible to switch to two stages in which water is stored,
In addition, a drain valve 20 for completely draining water inside the main body 1 is connected to the conduit 1.
It is provided at the lowest part of 3. After operating the drain valve 20 to remove water from the main body 1, conduit 13, etc., the heater 15 is activated to generate dry hot air, and the fan 23 is configured to supply this dry hot air into the main body 1. has been done.
In addition, a communication path 21 communicating with the water storage section 12 is provided in a portion below the detector 16 in the middle of the heat exchanger 14, and is opened only within the main body 1 to prevent backflow from the water storage section 12. A check plate 22 is provided.

Furthermore, a motor-driven fan 2 is provided at the top of the heat exchanger 14.
3 is provided, and a communication path 24 communicating between this portion and the inside of the main body 1 is provided, and furthermore, a thermostat 25 is provided on the side surface of the water storage portion 12. Reference numeral 26 denotes a microwave irradiation device installed at the top of the main body 1, which is opened at the top of the main body 1 so that irradiation from the magnetron 27 can be irradiated to the top of the main body 1 through a passage 28 and an opening 28a. .

29 is a cover that surrounds the food tray 8;
is composed of two parts 29a and 29b, and while the food tray 8 is moving, the member 2 is connected by a link mechanism to be described later.
9a and 29b are opened so as not to obstruct movement of the food tray 8.

Furthermore, when the food tray 8 stops, the members 29a and 29b are closed via the same link mechanism to completely surround the food tray 8, and at this time, the microwave is emitted by the device 26. The food tray 8 is irradiated with the light. Regarding the specific opening/closing operation of the cover 29, referring to FIG.
The link member 31 is pivotally supported, and the other end of the link member 31 is pivotally supported on the cover member 29a. Further, the tip of the second lever 32 is pivotally supported on the pivot portion, and the other end of the second lever 32 is attached to the main body 1.
be pivoted to the top of the The tip of the second link member 33 is pivotally supported in the middle of the lever 32, the other end of the second link member 33 is pivoted to the tip of the third lever 34, and a link mechanism similar to that structure is also provided on the cover member 29b. let That is, when the first lever 30 is actuated, the cover member 29a is moved back via the first link member 31, and the member 29b is also moved back, so that the cover member 29 is in an open state.

When the third lever 34 is rotated, the cover member 29a moves forward via the second link member 33 and the second lever 32, and the member 29b also moves back and forth in the same way, creating a seal that completely surrounds the food tray 8. A chamber is formed, and at this time the microwave irradiation device 26 is activated to perform microwave irradiation. The cover members 29a, 29b are provided with cutouts 35, 35 so that the tips of the arms 7 do not get in the way during this encircling, and also to prevent the surface of the food from drying out during microwave irradiation. A water injection nozzle 36 is provided.
Reference numeral 37 denotes an injection nozzle facing above the heater 15 of the heat exchanger 14 for obtaining heated steam. The spray is turned into heated steam by the heater 15, and the heated steam is filled into the main body 1 via the fan 23. In addition, 40 is a humidity controller, which can be seen inside the main body 1, and this is a solenoid valve 39.
control.

Reference numeral 41 denotes a spray nozzle facing the top of the main body 1, which is activated by the opening/closing operation of a solenoid valve 42, and is configured to perform spraying for a certain period of time with a timer 43.

In the above configuration, the lower detector 17 is activated,
When the water level is lowered to this position and the heater 15 generates heat, moist hot air is generated. This moist hot air fills the main body 1 and heats the frozen food with the moist hot air. By the circulation rotation of the main body 1, the inside of the main body 1 is evenly filled, and by the thawing means of the moist hot air, the frozen food is kept moist and maintains the characteristic of the food, preferably from the maximum ice crystal formation zone. ) Primary thawing is performed by raising the temperature to the lower temperature range.

Thereafter, when the food tray 8 circulates within the main body 1 and comes to the microwave irradiation position, the cover members 29a and 29b are operated by the link mechanism to surround the food that has been thawed with the moist hot air. Microwave irradiation, which is secondary defrosting, is performed by a microwave irradiation device in a moist hot air atmosphere. At this time, the microwave irradiation acts cooperatively with the moist hot air to raise the temperature by passing through the maximum ice crystal formation zone at once, and thaws the parts that have not been thawed by the moist hot air, such as pieces of meat, and further The food is then reheated and rapidly raised to a suitable temperature for consumption. Furthermore, after all the water in the main body 1, the conduit 13, etc. is removed, the heater 15 is operated to generate dry hot air, and this dry hot air can be supplied into the main body 1 by the air supply force of the fan 23. It is possible. In this case, the frozen food is first thawed by dry hot air, and then subjected to secondary thawing or thawing reheating by dry hot air and microwave irradiation from the final stage of thawing, that is, near the maximum ice crystal formation zone.

Next, the drain valve 20 is opened to drain all the water inside the main body 1, the conduit 13, the heat exchanger 14, etc., and when the heater 15 generates heat and the fan 23 is turned, the air heated by the heater 15 flows into the communication path. 24, through the main body 1, to the conduit 13, and further circulated to the heat exchanger 14 to blow the food inside the main body 1 with dry/moist hot air,
Alternatively, it may be heated with dry/moist hot air, but the temperature is controlled by a thermostat 25.

In this case, when water is injected from the nozzle 37 facing into the heat exchanger 14, the sprayed water becomes heated steam and circulates in the same way as the dry hot air or dry hot air, and the inside of the main body 1 is heated. It will be filled with water vapor. Thus, in the same way as above, frozen foods undergo primary thawing using heated steam, and then, from the final stage of thawing, that is, near the maximum ice crystal formation zone, they undergo secondary thawing or thawing through combined heating using heated steam and microwave irradiation. It undergoes reheating. Furthermore, when the detector 16 is operated to ensure that a certain amount of water always exists in the water storage section 12 and the water is heated by passing current through the heater 15, the water in the storage water section 12 is heated by the thermostat 25. The frozen food on the lowest food tray 8 is immersed in hot water and first undergoes primary thawing, and then from the final stage of thawing, that is, around the maximum ice crystal formation zone, it is exposed to the hot water atmosphere and microwave. By irradiation: undergoes subsequent thawing B or thawing and reheating. In each of the above embodiments of the present invention, the frozen food is first thawed by dielectric conduction heating means such as dry hot air, moist hot air, heated steam, etc., and then at the end of the primary thawing, that is, near the maximum ice crystal formation zone. Then, it is subjected to secondary thawing by the dielectric conduction heating means and the dielectric internal heating means using microwave irradiation.

Therefore, as is clear from this explanation, the end point of the primary thawing (starting point of the secondary thawing) is approximately -5°C, although there are slight differences depending on the type of frozen food. At this time, a brief explanation will be given of how to know the starting point, that is, the temperature at which the secondary thawing is performed after the primary thawing ends.

Dithermal conduction heating means as applied to the primary thawing of the present invention,
In other words, when external heating is applied, the temperature of food during thawing increases as follows:
Looking at multiple groups of thawing curves created at various depths from the surface, it can be seen that in the temperature range below -5°C, which is the lower limit of the maximum ice crystal formation zone, there is a temperature difference between the inside and outside of the food after the same heating time. are not significantly different except for their outer surfaces, and this is generally well known in the art.

Therefore, it is preferable to measure the temperature slightly inside the frozen food, excluding the outer surface.For example, a thermistor temperature measuring device is used as the measuring device, and the sensor is placed inside the surface of the food (sample). Just insert it. However, this measurement is only a laboratory method and is not practical for actual defrosting and reheating cooking. Therefore, it is sufficient to implement a means for indirectly measuring the temperature of food as described below. For example, a large number of thawing curves are created in advance, taking into consideration the types and conditions of frozen foods, the types and conditions of dithermal conduction heating means, etc., and programs are created and stored in a microcomputer based on these curves. can be measured very easily by combining it with electrical operation means. The present invention is as described above and has the following effects.

That is, the method of the present invention uses dry hot air, moist hot air,
The induction heating device is selected by operating the operating means according to the type of frozen food and its conditions from among multiple types of dithermal conduction heating means such as heating steam generators, infrared ray generators, hot water immersion devices, etc. Since the food is pre-heated and thawed using heat conduction heating means, the ingredients, composition, moisture content,
It can handle a variety of frozen foods with different flavor conditions, packaging conditions, and optimal eating temperatures, and the built-in heating and defrosting functions can be used in any combination, making it possible to use conventional single heating or one type of induction heating. The functions of the combined heating method of conduction heating means and dielectric internal heating means have been fundamentally improved, and the conventional problems have been solved by creating an all-menu complete defrosting, defrosting and reheating cooking method. In this case, the important thing about the present invention is that the frozen food can be cooled only by dielectric conduction heating means that correspond to the type and conditions of the frozen food.
8. It is a method of first thawing frozen foods by pre-heating them. This eliminates the phenomenon of overheating on the surface and corners of frozen foods, and evenly heats the inside to raise the temperature, making it ideal for reducing quality. This can be prevented. Further, in the present invention, after the frozen food is preheated and primary thawed using the dithermal conduction heating means, the dielectric conduction heating means and the dielectric internal By using a cooperative combination with a heating means, the food is subjected to a compound heat treatment and subjected to secondary thawing or thawing and reheating cooking, so that the following synergistic and supplementary effects are exhibited.

This will be explained by the following example. Example: A sample of frozen cooked rice (nigiri-meshi) was taken out of the freezer and placed in a small complex thawing device maintained under predetermined heating conditions (open heating alone, microwave irradiation alone, open heating + microwave irradiation) and heated to thaw. do.

Thereafter, the sample was immersed in a known amount of water in a thermos flask, and the absorbed heat was measured. However, the open heating temperature is 110℃
, microwave heating 490W (2450MHz).
According to the above measurement method, the amount of heat given to frozen cooked rice was calculated from the temperature rise of water in a thermos flask for each of open heating alone, microwave heating alone, and open heating + microwave heating.

The results are shown in Table 2 below. <Data analysis> Sample Moisture content: 58.0% Approximate specific heat of food using MOnvOisin formula (1) Energy given to microwave heating food E1 Therefore, CW=0.748C1=0.458- Freezing point O
(2) Energy given to open heated food IC2 (3) Energy given to compound heated food E3 Corrected for evaporated water. There is.

Therefore, as a result of the above calculations, it has become clear that when open heating and microwave heating are combined, the energy is simply added.

Also, when calculating the average temperature of food when heated under each condition from this data, the average temperature is 3.
．． 9° C. Therefore, from the above calculation, it can be seen that the combined heating of the present invention exhibits a temperature increasing effect, that is, a synergistic effect, which is greater than the simple addition of open and microwave heating alone.

In addition, the results of the sensory taste test of the sample were extremely good. Figure 4 shows the thawing temperature rise curves for each heating condition (open heating alone, open heating + microwave irradiation) based on the above calculation results, and the one method of the present invention shows the maximum ice crystal formation zone. It is obvious that the ice is rapidly passing through it, and it has been shown that rapidly passing through this zone of maximum ice crystal formation means that the eating temperature is reached extremely quickly.

It should be noted that the above examples were carried out by the Osaka Research Institute of Osaka Gas Co., Ltd.

According to the above examples, the method of the present invention quickly passes through the zone of maximum ice crystal formation as described above, so the cell tissue of the food is not destroyed, and the umami flavor components (trips) do not flow out from the tissue. The flavor of the food does not change after thawing or thawing and reheating. At this time, in particular, the present invention does not perform composite heating by combining dithermal conduction heating and dielectric internal heating from the beginning of thawing, but rather performs composite heating in the subsequent stage of thawing and reheating after that. Not only does the problem described at the beginning of the defrosting method disclosed in Publication No. 37-13733 and US Pat. No. 3,569,656 not occur, but electricity costs can be saved by projecting microwaves from the beginning. In this case, the influence of microwaves on food in the latter stage of thawing (during secondary thawing) of the method of the present invention is due to an increase in food moisture content (first stage).
(see table) and because of the short irradiation, there is almost no effect, and combined heating from a specific temperature range produces a synergistic temperature-raising effect as described above. and each heating method (dithermal conduction heating,
They compensate for the shortcomings of dielectric internal heating, surface moisture conditioning), that is, they exhibit complementary effects together, and the knowledge of these synergistic and complementary effects is the advocate of the present inventors, and is the subject of academic research. It also has great significance. As described above, the present invention is revolutionary as a method for most effectively defrosting or defrosting and reheating various frozen foods or cooked frozen foods, and makes a significant contribution to the refrigeration industry.

[Brief explanation of the drawing]

The drawings show an example of a device directly used in the present invention, and FIG. 1 is a vertical front view, FIG. 2 is a sectional view of the same side, FIG. 3 is a partially enlarged view of the microwave irradiation device, and FIG. 4 is a thawing diagram. This shows a temperature rise curve.

Claims (1)

[Claims] 1. Select the operation according to the type of frozen food and its conditions from among the multiple types of dielectric conduction heating means installed in the refrigerator, such as dry hot air, moist hot air, heated steam generation devices, hot water soaking devices, etc. After the food is preheated and primarily thawed using the selected dithermal conduction heating means by operating the means, the food is then heated in combination with the dielectric conduction heating means and the dielectric internal heating means. A method for thawing, thawing and reheating food by compound heating, characterized in that the food is subjected to a compound heat treatment and subjected to secondary thawing or thawing and reheating cooking.