JPH08261620A - Vacuum cooling method - Google Patents

Abstract

PURPOSE: To cool an article with high efficiency in a short time by dividing a temperature in a cooling tank into several stages of temperature zones in conformity with the type of cooled article and an initial temperature and so forth and setting an evacuation speed in conformity with the article for each temperature zone and cooling the article. CONSTITUTION: An article is housed in a cooling tank 1 air-tightly and the cooling tank 1 is decompressed with a vacuum suction means 2. The evacuation speed of the evacuating means 2 is introduced with air introduction valves 4 to 7 installed to an air supply passage 3. The air introduction valves 4 to 7 and the evacuating means 2 are used to divide the temperature in the cooling tank 1 into several states of temperature zones in conformity with the type of the cooled article and an initial temperature and so forth, thereby setting the evacuation speed in conformity with the cooled article for each temperature zone and cooling the article under control by means of a control device 10. This construction makes it possible to cool with high efficiency in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum cooling method for cooling an object to be cooled, such as cooked food, in a short time.

[0002]

2. Description of the Related Art As is well known, when heat-cooked food is packed in a container and shipped, if the temperature remains high, water drops will adhere to the inner surface of the lid of the container and the like, which will not only make it look bad, but will also prevent the adhered moisture from adhering. In order to spoil the flavor by dripping it on food, it is put in a container or a lid after cooling. By the way, in a food factory such as a lunch box that is mass-produced, it is required to perform this cooling in a short time. Therefore, vacuum cooling is performed in which the cooked food is stored in a cooling tank, and the cooling tank is evacuated to actively evaporate the moisture in the food, and the latent heat of vaporization at the time of evaporation is removed from the food to cool it. The method is receiving attention. However, the conventional vacuum cooling method only cools by uniformly reducing the pressure, and then rapidly returns to atmospheric pressure after cooling (hereinafter, this operation is referred to as recompression). In some cases, the form and properties were destroyed or deteriorated to impair the commercial value. For example, in soups, beverages, etc., due to the bumping phenomenon, scattering from the container occurs, and also kneaded products such as kamaboko and rice paste,
Regarding an article having a hard surface and a rough inside such as a deep-fried food such as tempura, the surface thereof is cracked due to the rapid boiling of moisture in the inside. That is, it is difficult to cool foods as described above by simply performing a simple and unified operation of simply cooling by decompressing and rapidly restoring pressure as in the conventional vacuum cooling method, and the commercial value of foods. If decompression and re-compression are performed slowly so as not to damage the cooling time, it takes a long cooling time and a lot of wasted time.

[0003]

SUMMARY OF THE INVENTION Therefore, the problem to be solved by the present invention is to vacuum cool an object to be cooled efficiently and in a short time without deteriorating its properties or destroying its shape. Is to provide a method.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, in which an object to be cooled is housed in a cooling tank, and the inside of the object to be cooled is evacuated by vacuum exhaustion. In the method of cooling by evaporating the water content of the product and removing the latent heat of vaporization at that time from the object to be cooled, the temperature in the cooling tank is divided into several temperature zones according to the type of the object to be cooled, the initial temperature, etc. The first feature is that the cooling is performed by setting the exhaust speed according to the object to be cooled for each temperature zone, and when the cooling tank is returned to the original pressure after cooling, the inside of the cooling tank A second feature of the vacuum is that the pressure is divided into several pressure bands according to the type of the object to be cooled, and the pressure is restored by setting the pressure-recovery speed according to the object to be cooled for each pressure band. It is a cooling method.

[0005]

According to the method of the present invention, the temperature of the object to be cooled is divided into several temperature zones according to the type, the initial temperature, etc., and the exhaust speed corresponding to the object to be cooled is set for each temperature zone. As a result, the object to be cooled is cooled while preventing abrupt evaporation of water. At the time of re-compression, the pressure zone is divided into several stages according to the type of the object to be cooled, and by controlling the pressure re-compression speed that matches each, a rapid change in the pressure difference between the inside and outside of the object to be cooled can be prevented. Pressure is restored while preventing.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a drawing for explaining a schematic configuration of an example of an embodiment of a vacuum cooling method according to the present invention,
FIG. 2 is a diagram for explaining a cooling pattern in the vacuum cooling method according to the present invention, and FIG. 3 is a diagram for explaining a recompression pressure pattern in the vacuum cooling method according to the present invention.

According to the present invention, the temperature in the cooling tank is divided into several temperature zones according to the type of the object to be cooled, the initial temperature, etc., and the exhaust speed according to the object to be cooled is set for each temperature zone. Since it is a vacuum cooling method of cooling by cooling, the vacuum cooling device, as shown in FIG. 1, has a cooling tank (1) for hermetically containing an object to be cooled,
Vacuum suction means (2) for decompressing the cooling tank (1) and the air supply path
Air introduction valves (4) to (7) provided in (3) for adjusting the exhaust speed by the vacuum suction means (2), temperature detection means (8) in the cooling tank (1), and this temperature detection means A control device (10) for controlling the vacuum suction means (2) and the air introduction valves (4) to (7) based on the signal from (8) is provided. Furthermore, when returning the cooling tank (1) to the original pressure after cooling, the pressure in the cooling tank (1) is divided into several pressure zones according to the type of the object to be cooled, and each pressure zone is divided into several pressure zones. Since the pressure is restored by setting the pressure recovery speed according to the object to be cooled,
An air introduction valve (4) to (7) provided in (3) for adjusting the introduction speed of air into the cooling tank (1), that is, the recompression pressure speed,
Pressure detection means (9) in the cooling tank (1) and this pressure detection means
A control device (10) for controlling the air introduction valves (4) to (7) based on a signal from (9).

The cooling tank (1) is provided with an opening / closing door (not shown) for work such as putting in / out of an object to be cooled and the like, and the opening / closing door has a sealable structure. The vacuum suction means (2)
Is connected to the cooling tank (1) via a check valve (11). As the vacuum suction means (2), for example, a liquid ring type vacuum pump or an ejector type vacuum pump can be used. In the following description of the embodiments, a liquid ring vacuum pump is used. The suction path (3) is a vacuum suction means.
It is for adjusting the pumping speed according to (2). That is, by selectively opening / closing each of the air introduction valves (4) to (7) to adjust the amount of air introduced from outside the system, the amount of vacuum exhausted by the vacuum suction means (2) is leaked. This is done by adjusting the amount. The intake passage (3) is for introducing outside air into the cooling tank (1) when the pressure in the cooling tank (1) is restored after cooling, and each of the air introduction valves (4) to (7) ) Is selectively opened and closed to regulate the amount of outside air introduced from outside the system. In addition, this air supply route (3)
A filter (12) for removing dust, germs and the like in the outside air introduced into the cooling tank (1) and preventing the adhered matter from being cooled is connected to the upstream end of the. Where each air inlet valve
The air introduction amount (ventilation resistance) of (4) to (7) may be the same, but it is preferable that the air introduction amount is different for each and the air introduction valves (4) to (7) are appropriately selected. By selecting and opening and closing the number of the above, it is possible to adjust to various types of air introduction amount as compared with the case where the air introduction amount (ventilation resistance) is the same. Further, the number of air introduction valves is not limited to four as in the illustrated embodiment, but at least two or more as long as the air introduction valves are selectively opened and closed as in this embodiment. The number may be any number as long as a combination of the exhaust speed and the re-pressurization speed applicable to the property of the object to be cooled is obtained as described later. The control device (10) receives the signals from the temperature detecting means (8) and the pressure detecting means (9) as described above, and also receives the vacuum suction means (2) and the air introduction valve (4)- Control the entire device including the control in (8). That is, the control device (5) stores the object to be cooled in the cooling tank (1) and then activates the vacuum suction means (2) to reduce the pressure in the cooling tank (1), ) After cooling by lowering the pressure in the cooling tank, air is introduced into the cooling tank (1) to cool it.
(1) Re-pressurize the inside. Further, the control device (10) intermittently or continuously inputs signals from the temperature detecting means (8) and the pressure detecting means (9) at predetermined intervals, and depending on the case, Depending on the time, by the procedure preset for each type of the object to be cooled by the control device (10),
The air inlet valves (4) to (7) are selectively opened and closed.

Now, an example of a cooling operation in the vacuum cooling device having the above structure will be described with reference to FIGS. In the present invention, all of the air introduction valves (4) to (7) are closed or 1 depending on the type of food to be cooled and the temperature range of the initial temperature. It controls whether to open one piece or several pieces and close the rest, or to open all the pieces. In the example shown in FIG. 2, the initial temperature of the object to be cooled is 80 ° C., and the cooling temperature is 70 ° C., 60 ° C. ℃, 45
The exhaust rate, that is, the cooling rate is controlled for each of the temperature zones A, B, C, and D divided by ° C. In this example, the air introduction amount of each of the air introduction valves (4) to (7) is set to increase in the order of the air introduction valves (4) to (7).
First, in the first temperature zone A (70 to 80 ° C.), the cooling rate is controlled by closing all of the air introducing valves (4) to (7) or by opening one of them. In this case, the more the air introduction valve with the larger air introduction amount is opened, the greater the amount of leakage with respect to the amount of vacuum exhausted by the vacuum suction means (2), and the decompression rate in the cooling tank (1) decreases. The speed can be reduced. That is, in the temperature band A shown in FIG.
The leftmost curve is the state in which all of the air introduction valves (4) to (7) are closed.Hereinafter, the one on the right side shows each air introduction valve (4).
(7) shows the state in which the air introduction amount is increased in the order of increasing air introduction amount, and the curve on the right side has a smaller depressurization rate and a smaller cooling rate. In the next temperature band B (60 to 70 ° C), temperature band A
Similarly, the cooling rate is controlled by closing all of the air introduction valves (4) to (7) or by opening one of them. In addition,
In FIG. 2, for simplification of description, the cooling rate is controlled following the state where the air introduction valve (6) is opened and the pressure is reduced in the temperature zone A (second curve from the right in the figure). Only the case is illustrated. In this state, the cooling rate is controlled by closing all the valves except the air introducing valve (7) having the largest air introducing amount or by selectively opening one. Subsequent temperature range C (45-60 ℃), D (-45)
In the same manner as the temperature zone A, the cooling rate is controlled by closing all of the air introducing valves (4) to (7) or by selectively opening one. In the temperature range D (up to 45 ° C),
The curve on the right shows the state in which all air introduction valves (4) to (7) are opened, and the curve on the left shows the state in which all air introduction valves (4) to (7) are closed. Here, an air introduction valve having a larger air introduction amount (smaller ventilation resistance) is selected as the object to be cooled has a large water content such as a soup or a beverage and is likely to cause a bumping phenomenon. To slow down the cooling rate. In addition, the above-mentioned problems due to vacuum cooling become less likely to occur as the temperature zone decreases, so in the temperature zone on the lower temperature side than the cooling rate on the temperature zone on the high temperature side, the air introduction amount is smaller (the ventilation resistance is larger). ) It is preferable to select and open the air introduction valve to increase the cooling rate in order to shorten the cooling time. If the object to be cooled has a strong tendency to confine and retain water vapor inside, such as kamaboko or fried food, as shown by the chain double-dashed line in FIG.
It is preferable to maintain a constant temperature (saturation temperature corresponding to the equilibrium pressure) for a predetermined time (for example, about 1 to 2 minutes), slowly release the vapor inside the object to be cooled, and reduce the pressure.

As described above, after cooling to a predetermined temperature, as shown in FIG. 3, the air introducing valves (4) to (7) are made to function as return valves at the time of pressure recovery as well as at the time of cooling. , Air introduction valves (4) to (7) according to the type and pressure relationship of the object to be cooled
Controls whether all are closed, one or a few are opened and the rest are closed, or all are opened. In the example shown in Fig. 3, the pressure range is 150mmHg, 400mmHg, 600mm.
Dividing by Hg, pumping speed for each pressure band E, F, G, H,
That is, the re-compression speed is controlled. First, in the first pressure zone E (up to 150 mmHg), the re-compression speed is controlled by opening all of the air introducing valves (4) to (7) or by selectively opening one of them. In this case, as the air introduction valve with the larger air introduction amount is opened, the air introduction amount into the cooling tank (1) is increased and the re-compression speed is increased. That is, in the pressure zone E shown in FIG. 3, the leftmost curve is the air introduction valves (4) to (7).
Shows the state where all the air introduction valves (4) to (7) are opened so that the air introduction amount increases according to the one on the right side. The speed is low. In the next pressure zone F (150 to 400 mmHg), like the above-mentioned pressure zone E, all of the air introduction valves (4) to (7) are closed or one of them is opened to control the re-compression speed. To do. In FIG. 3, for simplification of description, the pressure is continuously restored after the state where the air introduction valve (5) is opened to restore pressure in the pressure zone A (second curve from the right in the figure). It is shown only when controlling the speed.
In this state, the air introduction valve with the smallest air introduction amount (4)
The return pressure speed is controlled by selecting and opening one valve other than. Subsequent pressure zone G (400-600mmH
g) and H (600 mmHg-), the cooling rate is controlled by opening all of the air introduction valves (4)-(7) or by selectively opening one of them as in the pressure zone E. The pressure band G
(400 ~ 600mmHg), H (600mmHg ~), the curve on the right shows the state where the air introduction valve (7) with the largest amount of air is opened, and the curve on the left shows the total air introduction valves (4) to (7). Shows the opened state.

In the vacuum cooling method described above, problems such as food cracking and soup splashing can be solved by unit time, unit temperature,
And the degree of water evaporation per unit surface area and the degree of organizational properties of food, and the decrease in bulk is the degree of pressure difference between inside and outside of food at the time of recompression and the degree of organizational properties (softness, etc.). It is based on the finding that it is caused by the relationship with. Therefore, at the time of cooling, the degree of water evaporation amount in each temperature band is previously obtained (or theoretically obtained) for each object to be cooled, and based on this degree, internal cracking or scattering Cooling rate (ie corresponding pumping speed) without
Can be set. Further, at the time of re-pressurization, the limit value of the pressure difference is preliminarily tested from the relationship between the pressure difference between the inside and the outside of the object to be cooled and the degree of organizational property (softness, etc.) in each pressure zone for each object to be cooled. Then, based on this, it is possible to set the re-compression speed without causing a decrease in bulk. For example, with rice, the more the pressure is rapidly reduced, the more the bulk decreases in the direction of weight. By pressing, it becomes possible to suppress the decrease in bulk to a small extent in a shorter time.

FIG. 4 is a drawing for explaining the schematic structure of another embodiment of the vacuum cooling method according to the present invention.
In the embodiment shown in FIG. 1 described above, the case where a plurality of air introduction valves (4) to (7) are used in the air supply path (3) has been shown, but in the embodiment shown in FIG. A motor-operated valve (13) whose air introduction amount (ventilation resistance) can be changed continuously or in several steps is used.

Further, as shown in FIG. 4, as a method of controlling the cooling rate, there is also a method of controlling the leak amount of the vacuum suction means (2) itself by the electric valve (14) continuously or in several steps. At this time, in the leak pipe (15), like the above-mentioned air supply path (3), dust and other germs in the outside air introduced into the cooling tank (1) are removed and adhered to the object to be cooled. A filter (15) for prevention is connected. Furthermore, the exhaust speed may be adjusted by controlling the vacuum suction means (2) itself. For example, in the case of the water-sealed vacuum pump mentioned above, by controlling the rotation speed of the prime mover,
With an ejector-type vacuum pump, this can be done by controlling the amount of water supply, that is, by controlling the number of revolutions of the water supply pump. Further, regarding the control of the exhaust speed and the pressure-recovery speed, the respective configurations described above can be combined with each other. In addition, when controlling the cooling speed and the pressure-recovery speed stepwise, it is as described above. However, when controlling continuously, the temperature and the pressure are continuously detected and the detected values are made to correspond to each other. The cooling rate and the pressure-recovery rate may be controlled continuously, but in practice, the temperature band and the pressure band may not be divided very finely and may be controlled in appropriate ranges.

[0014]

As described above, according to the vacuum cooling method of the present invention, the temperature is divided into several temperature zones according to the type of the object to be cooled, the initial temperature, etc. By setting the exhaust speed according to the object to be cooled, cooling is performed while preventing rapid evaporation of water inside the object to be cooled. By dividing the pressure band into several stages and controlling the recompression pressure speed that matches each, the pressure is restored while preventing a sudden change in the pressure difference between the inside of the object to be cooled and the atmospheric pressure.
It becomes easy to cool the object to be cooled, which has been difficult with the conventional vacuum cooler. Further, with the above configuration, it is possible to select a wide cooling rate suitable for the object to be cooled. In particular, when cooling food, you can select a wide range of cooling rates that match the food,
Not only is it easier to cool difficult foods, but wasteful cooling time is reduced and cooling is possible in a short time. This allows
Even foods that have been difficult to cool with a conventional vacuum cooler due to problems such as cracking, scattering, and reduction in bulk can be cooled according to the respective foods without dead time.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a schematic configuration of an example of an apparatus for implementing a vacuum cooling method according to the present invention.

FIG. 2 is a diagram for explaining a cooling pattern in the vacuum cooling method according to the present invention.

FIG. 3 is a diagram for explaining a recompression pattern in the vacuum cooling method according to the present invention.

FIG. 4 is a diagram for explaining a schematic configuration of another embodiment of the vacuum cooling method according to the present invention.

[Explanation of symbols]

 (1) Cooling tank (2) Vacuum suction means (3) Air supply path (4) Air introduction valve (5) Air introduction valve (6) Air introduction valve (7) Air introduction valve (8) Temperature detection means (9) Pressure detection means (10) Control device (11) Check valve (12) Filter

Claims (2)

[Claims] 1. An object to be cooled is housed in a cooling tank (1), and the inside of the cooling tank (1) is evacuated to evaporate moisture in the object to be cooled, and the latent heat of vaporization at that time is transferred to the object to be cooled. In the method of cooling by taking away from the cooling tank (1), the temperature in the cooling tank (1) is divided into several temperature zones according to the type of the object to be cooled, the initial temperature, etc. A vacuum cooling method characterized in that cooling is performed by setting a pumping speed. 2. An object to be cooled is housed in a cooling tank (1), and the inside of the cooling tank (1) is evacuated to evaporate the moisture in the object to be cooled, and the latent heat of vaporization at that time is transferred to the object to be cooled. When the cooling tank (1) is returned to its original pressure after cooling in the method of cooling by taking away from it, the pressure in the cooling tank (1) is divided into several pressure bands according to the type of the object to be cooled. A vacuum cooling method, characterized in that the pressure is restored by setting a pressure-regaining speed according to the object to be cooled for each pressure zone.