JP4744567B2 - Freezer refrigerator - Google Patents

Description

  The present invention relates to a method for freezing and storing foods using a frozen storage technique and a refrigerator-freezer.

In recent years, in home refrigerators, there are increasing opportunities for home-freezing cooked rice from each home. Originally, cooked rice is said to be most delicious when cooked, but it takes time and effort to cook as much rice as necessary when needed.
Therefore, home-freezing and storing the cooked rice has become common as a simple and convenient storage method as well as keeping warm in a rice cooker.

However, if you cook a lot of cooked rice with a rice cooker and eat it in multiple batches, the cooked rice will turn yellow or dry over time. It was impossible to eat as deliciously as it was cooked.
For this reason, as a solution to these problems, a container for storing cooked rice, a heating means for heating the cooked rice in the container to 71 to 73 degrees and keeping it warm, and the atmospheric pressure in the container to 20 to 93 Kpa. There is a rice cooker including a decompression means (see, for example, Patent Document 1).

In addition, if you cook a large amount of cooked rice and store it, and thaw it in the range, thaw it at room temperature, etc., and then place it in the freezer. It will be frozen.
This is because there are many cases where frozen foods are already contained in the freezer compartment, and it is easy to think that there is a possibility that the frozen foods will be adversely affected if hot foods are put directly. However, freezing the cooked rice after cooling to room temperature in this way is troublesome in that it requires a two-step process to preserve the cooked rice, and is also not good for the quality of the cooked rice. .
Therefore, in order to solve this problem, a refrigerator (see, for example, Patent Document 2) that rapidly cools the target food by putting food with residual heat in a small-capacity space, or hot food in the freezer compartment There is also a refrigerator provided with a cooling unit for the purpose (see, for example, Patent Document 3).

In addition, in the case of storing a large amount of cooked rice for freezing, there are many complaints that cooked rice that has been thawed in a range is hard, easy to dry, and not delicious.
Thus, many proposals have been considered for suppressing the deterioration of the taste when the cooked rice is frozen. For example, a method for freezing processed foods that, when the cooling rate of cooked rice is specified, and the maximum ice crystal formation zone passage time is set to 15 to 20 minutes and natural thawing or microwave thawing is obtained, is almost the same quality as before freezing. (For example, refer to Patent Document 4) In addition, in the quick freezing process of cooked rice food, temporary cooling is stopped, the temperature in the freezer is rapidly increased within a time period in which the object to be frozen does not reach thawing, and left for a short time. There was also a method for producing a frozen cooked rice food that was further rapidly frozen to freeze the cooked rice food (see, for example, Patent Document 5).
Japanese Patent Laying-Open No. 2005-253318 (first page, FIG. 1) Japanese Patent Laying-Open No. 2007-212053 (first page, FIG. 1) Japanese Patent Laying-Open No. 2005-226984 (first page, FIG. 1) Japanese Patent Publication No. 9-500542 (first page, FIG. 1) JP-A-5-23121 (first page, FIG. 1)

  A rice cooker that keeps cooked rice deliciously while preventing warming odor and yellowing is described in Patent Document 1, but the storage period is not clearly mentioned, and even from the characteristics of general rice cookers, 1 It can be said that this corresponds to storage for about 2 days. Therefore, even if it can preserve | save in the state close | similar to cooking, the period which can be preserve | saved is very short, and it does not reach the level of reducing the frequency | count of cooking rice and reducing the burden of housework.

In addition, the advantage of home-freezing cooked rice that has been cooked a lot is that it can be stored for a long period of time, and the cooked rice immediately after thawing the range looks and feels better than what has been kept warm in a rice cooker for a long time. Both are close to cooking. However, the cooked rice after thawing the range tends to become hard after a while, and the texture becomes far from the cooked rice before freezing.
In order to solve this problem, Patent Document 1 describes a refrigerator that rapidly cools a target food material by introducing a food material having residual heat into a small-capacity space. However, the texture after thawing was not improved dramatically.

  In addition, as a method for improving the taste of frozen cooked rice, Patent Document 3 describes a refrigerator having a device that can be cooled at a cryogenic temperature during freezing, but the refrigerator needs to use a device that can be cooled at a cryogenic temperature. In addition, it was a large-scale device for freezing surplus cooked rice at home.

  The present invention has been made in order to solve the above-described problems, and intensively cools a warm food such as cooked cooked rice so that it undergoes a supercooled state when it is frozen. It is possible to save the trouble of cooling and freezing hot food such as standing rice, and to improve the quality after freezing and thawing, and by improving the cooling and freezing method A method for freezing and storing food and a refrigerator-freezer capable of obtaining the effect are obtained.

The refrigerator-freezer according to the present invention includes a freezer compartment that is settable in a freezing temperature zone and has a quick cooling function, a case that stores food installed in the freezer compartment, a high food temperature in the case, and A temperature sensor capable of recognizing a food charging position; at least two or more cold air outlets for blowing out cold air into the case; and damper means for controlling the feed of the cold air to the cold air outlets. A refrigerator-freezer that performs a frozen storage method for foods that controls the damper means based on the temperature detected by a sensor to freeze-store foods containing starch such as cooked rice , wherein the foods are stored frozen. When the temperature is high , cold air is intensively blown out from the cold air outlet close to the food charging position and rapidly cooled at a cooling rate of 0.5 ° C./min. When the temperature range of 0 to 1 ° C is reached, the rapid cooling is stopped to weaken the cooling capacity, and the cold air is blown out from the cold air outlet other than the cold air outlet close to the food charging position, and then the food temperature is frozen. When the temperature near the point temperature is reached, the food is cooled with cool air in a range where the air temperature around the food does not fall below -15 ° C to bring the food into a supercooled state. The supercooling is released, and then normal frozen storage is performed.

Refrigerator according to the present invention is to implement a method of refrigeration of the food to frozen foods containing starch, such as rice, at the time of the food temperature is hot and rapid cooling at a cooling rate of more than 0.5 ° C. / min Thereafter, when the food surface temperature reaches a temperature range of 40 to 1 ° C., the rapid cooling is stopped to weaken the cooling capacity, and then the food ambient air temperature is −15 when the food temperature reaches near the freezing point temperature. Cool the product with cool air that does not fall below ℃ to bring the food into a supercooled state. After a predetermined time, perform quick cooling to release the supercooled food from being supercooled, and then perform normal frozen storage. As a result, it is possible to rapidly cool high-temperature foods such as cooked cooked rice without rough cooling, which suppresses chemical changes such as aging that occurs at a temperature higher than the freezing temperature of the foods and bacterial growth. , Contained in the food Since the transpiration of water is suppressed and the food is frozen through supercooling, the ice crystals generated by freezing can be stored in high quality without destroying the internal structure of the food, and the fineness of the ice crystals In the case of foods containing starch such as cooked rice from the position where ice crystals are generated, re-gelatinization at the time of reheating is promoted, so the texture close to that before freezing is maintained as compared with the conventional thawed product after freezing It has the effect of being able to.

Embodiment 1 FIG.
FIG. 1 is a method for frozen storage of food according to Embodiment 1 of the present invention, and is a schematic diagram showing the difference between a method for freezing cooked rice and a conventional method for freezing cooked rice. FIG. The graph which shows the texture of the frozen cooked rice, FIG. 3 is the graph which showed the temperature change when water freezes with no supercooling (a) and with supercooling (b).
The frozen storage method proposed as Embodiment 1 of the present invention is a freezing method suitable for freezing food containing starch like cooked rice in a higher quality state, and is particularly a freezing method suitable for cooked rice.
Moreover, even if it is food other than starch containing foods, such as cooked rice, if it is a warm food, the effect which improves the frozen quality can be acquired.
About the following, the frozen preservation | save method and implementation | achievement means are demonstrated to an example for cooked rice.

  First, the method for freezing and storing food according to Embodiment 1 of the present invention, which is different from the method for freezing cooked rice and the conventional method for freezing cooked rice, will be described with reference to the schematic graph of FIG. In FIG. 1, the vertical axis represents temperature, the horizontal axis represents time, the solid line represents food core temperature, and the broken line represents food surface temperature.

(X) of FIG. 1 represents the temperature change of the cooked rice at the time of freezing in the conventional freezing method.
In the conventional freezing method, warm heat is taken by leaving warm cooked rice at room temperature before freezing. Therefore, in the temperature range of A, chemical reactions leading to quality deterioration related to the growth of bacteria, the color and odor of cooked rice, and the texture were likely to proceed.
Moreover, it existed in the state which aging of the starch which is a factor by which cooked rice becomes hard and becomes a poro by progressing in the temperature range of B for a long time.
Also, when the freezing temperature is normal, as in the C temperature range, the surface begins to freeze from the surface and completely freezes through the phase change state. Moisture is attracted to the rice grains, and the moisture in the rice grains tends to escape.Furthermore, ice crystals grow large in a needle shape, so the surface area where the starch molecules and water molecules come into contact with each other at the time of thawing is reduced, re-gelatinized and returned softly. It was difficult.

(Y) of FIG. 1 represents the temperature change of the cooked rice in the freezing preservation method of this invention.
In the frozen storage method of the present invention, since the cooked cooked rice can be directly put into a switching room that can be set in the freezing temperature zone and rapidly cooled, the propagation of bacteria in the temperature range of A and the cooked rice Chemical reactions that lead to quality degradation related to color, odor and texture can be suppressed.
Further, in the temperature range of B, since it is not frozen and rapidly cooled at the time of high temperature and phase change, the time in this temperature range can be shortened, and starch aging can be suppressed.
In addition, when frozen through a supercooled state so as to be in the temperature range of C, fine ice crystals are formed as a whole to the center of the rice grain, so the surface area where the starch molecules and water molecules come into contact with each other at the time of thawing is large, and it is easy to re-gelatinize. It is easy to return to the state, and a texture close to cooking is obtained.

A detailed cooling method in each cooling step will be described with reference to FIG.
In the temperature range of A, the temperature of the cooked cooked rice is high at 60 to 90 ° C, but the time until the cooked rice core temperature is cooled from 60 ° C to 10 ° C is, for example, about cooked rice wrapped in 150 g of wrap. Within 100 minutes, preferably within 70 minutes. That is, the cooling rate is 0.5 ° C./min or more, preferably 0.7 ° C./min or more.

About the temperature range of B, it is a temperature range where aging of starch is likely to proceed, from 40 ° C. to completion of freezing, preferably from 10 ° C. to the freezing point −2 ° C. To the freezing point of -2 ° C).
The time until the central temperature of the cooked rice reaches from 10 ° C. to −2 ° C. is, for example, less than 600 minutes, preferably less than 300 minutes, more preferably less than 100 minutes for cooked rice wrapped in 150 g. Is seen.
Regarding the region C, freezing quality improvement effect can be expected when frozen through a supercooled state, but the depth of supercooling (temperature difference between the freezing point of the food and the temperature reached by supercooling) is 1 ° C or more, When the temperature is preferably 3 ° C. or higher, more preferably 5 ° C. or higher, an effect effective for improving the freezing quality can be obtained.

FIG. 2 shows the texture measurement result of cooked rice. Texture means the mechanical properties felt when chewing food. In the figure, the vertical axis indicates stickiness, and the horizontal axis indicates hardness.
If cooked rice thawed after freezing is plotted at a position close to the cooking in the figure, it can be said that even when eaten, a texture close to that of cooking is obtained.
The cooked rice that has been rapidly cooled when it is warm and passed through a supercooled state (the depth of supercooling is 1 ° C. or higher, preferably 3 ° C. or higher, more preferably 5 ° C. or higher) It was plotted at a position closer to the cooking compared to, and the result was that both hardness and stickiness were close to cooking.

Here, the supercooling of water will be described.
FIG. 3 is a graph showing temperature changes when water is frozen with no supercooling (a) and with supercooling (b). The vertical axis of the graph is temperature, and the temperature increases as it goes upward. The horizontal axis is time, and the time elapses in the direction of the arrow.
The supercooled state refers to the temperature at which the substance begins to freeze. In other words, the supercooled state is a state where the temperature should start freezing but not frozen at all. For example, the freezing point of water is 0 ° C. This freezing point varies depending on the substance, and tends to be lower than 0 ° C. in foods having a high salt concentration and high sugar content.

The supercooling state and the freezing after the supercooling state will be described in more detail by taking water as an example. The supercooling state is a state of 100% water even when the freezing point falls below 0 ° C. when the water is cooled. Say.
Water that has entered a supercooled state can eventually freeze and become ice, but at this time, some kind of stimulation is necessary. This stimulus may be temperature or physical.
In this way, freezing can be started by stimulation, but the time from the supercooling state to the start of freezing is in units of several seconds and is instantaneous. However, the proportion of water that freezes instantaneously at the start of freezing is several percent of the total, and it takes further cooling time before it becomes 100 percent ice.

  Here, the difference between normal freezing and supercooled freezing will be described in comparison. First, the main difference between normal freezing and supercooling freezing is whether or not a supercooled state is entered. In the case of normal freezing, when the freezing point is passed, freezing starts without entering the supercooling state.

  Another major difference between normal freezing and supercooling freezing is the state at the start of freezing. Here, the phenomenon that occurs at the start of freezing will be explained using water in a plastic bottle as an example. In normal freezing, when freezing starts, the water near the surface of the plastic bottle begins to freeze. It becomes a state where thin ice is applied to the part, then the ice spreads toward the inside, and finally the whole freezes.

Ice growth occurs mainly around ice nuclei in which water molecules form clusters of a certain size or more, and ice nucleation occurs at the start of freezing. Therefore, in the case of normal freezing, most ice nuclei are formed on the surface, and it can be said that ice grows from there to a portion that is in a water state.
On the other hand, in the case of supercooled freezing, ice nuclei are uniformly formed in the entire PET bottle when freezing starts. And because the ice grows in every part of the PET bottle, both inside and on the surface, the ice never grows in a certain direction.
The difference between normal freezing and freezing after completion of freezing is due to the difference in the cooling process. In normal freezing, large acicular ice crystals from the surface to the inside are formed, whereas in freezing freezing. Produces uniformly small granular ice crystals on the surface and inside.

Further, in the case of quick freezing, the state at the start of freezing and after the completion of freezing is the same as in the case of normal freezing in that it is quickly frozen by applying cold air to the surface. First, the temperature of the surface suddenly drops, so it begins to freeze from the surface.
However, the difference from normal freezing is that the cooling rate to the inside increases, so that ice nuclei are more likely to form inside than normal freezing, and no larger ice crystals are formed than during normal freezing.

When considering food freezing, the size and shape of ice crystals after freezing has a significant effect on the quality of food when thawed. Since food is mostly composed of cells, proteins, carbohydrates, etc., once its structure is destroyed by ice crystals, it often cannot be completely restored.
Therefore, it can be said that freezing with good quality has been achieved if the size and shape of the ice crystals formed upon freezing does not destroy the original structure of the food.

As for cooked rice, when frozen through a supercooled state, fine ice crystals are formed as far as the center of the rice grain, so the surface area where the starch molecules and water molecules come into contact with each other during thawing is large, and it becomes easy to return to a soft state by re-gelatinization. Can be considered in principle.
The supercooled state can be kept unfrozen without being released, but in the case of cooked rice, aging of starch proceeds if it is in an unfrozen state. Accordingly, in the case of supercooled freezing of cooked rice, it is necessary to quickly release the supercooled state after the supercooled state and completely freeze it.

Next, the structure and control in the refrigerator-freezer for implementing the frozen storage method of Embodiment 1 of the present invention will be described in detail.
FIG. 4 is a side sectional view of a refrigerator-freezer that implements the freezing method, FIG. 5 is a side sectional view showing a switching chamber of the refrigerator-freezer that performs the freezing method, and FIG. 6 is an infrared sensor of the refrigerator-freezer that performs the freezing method. FIG. 7 is a graph showing the directivity characteristics of the infrared sensor of the refrigerator-freezer that implements the freezing method, FIG. 8 is a side sectional view showing the switching chamber of the refrigerator-freezer that implements the freezing method, and FIG. FIG. 10 is a perspective view showing the vicinity of the sensor mounting portion of the switching chamber of the refrigerator-freezer that performs the freezing method, and FIG. 10 is a perspective view showing the switching case of the refrigerator-freezer that implements the freezing method.

As shown in FIG. 4, the food storage room of the refrigerator-freezer for implementing the frozen preservation method of Embodiment 1 of this invention is arrange | positioned in the uppermost part, and the refrigerator compartment 100 provided with the open / close door, and refrigerator compartment 100 And a switching chamber 200 having a drawer door that can be switched from a freezing temperature zone (−18 ° C.) to a temperature zone such as refrigeration, vegetables, chilled, soft freezing (−7 ° C.), and the like. Are arranged in parallel with each other, and are arranged between the ice making chamber 500 having a tray drawer door, the vegetable chamber 300 having the drawer door arranged at the bottom, the vegetable chamber 300, the switching chamber 200 and the ice making chamber 500, It is mainly composed of a freezer compartment 400 provided with a drawer door.
An operation panel 10 for adjusting the setting of each room is provided on the door surface of the refrigerating room 100. On the back side of the refrigerating room 100, a temperature set by operating the operation panel 10 is set in each room. A control device 16 that controls opening and closing of the compressor and the damper is provided so as to adjust the temperature of the installed temperature detector.
The switching room 200 and the freezing room 400 of the refrigerator / freezer are spaces that allow rapid cooling and supercooling control.

As shown in FIG. 5, a thermopile 2 that is an infrared sensor that senses the temperature of input food such as cooked rice is attached to the front side of the ceiling of the switching chamber 200.
In addition, a thermistor for detecting the air temperature in the switching chamber 200 is attached above the switching chamber 200 on the back side.
This thermopile 2 is rotated 90 degrees or more up and down about the attachment point so that the temperature of the food stored in every position of the switching case 201 stored in the switching chamber 200 can be detected. Is provided. The thermopile 2 may be provided so as to rotate 180 degrees to the left and right about the support shaft so that the temperature of the food stored in any position of the switching case 201 can be detected.
The air temperature detected by the thermistor 3 is used for damper control for keeping the temperature of the switching chamber 200 at the set temperature. When the detected temperature of the thermistor 3 is higher than the set temperature, a damper described later opens and cool air is switched. When the temperature is lower than the set temperature, the damper closes and the cold air flow into the switching chamber 200 is prevented.

Next, the thermopile 2 will be described in detail with reference to FIGS.
As shown in FIG. 6, the thermopile 2 that senses food temperature includes a thermopile substrate 30 that is an infrared sensor body, a movable pile 31 that is integrally attached to the thermopile substrate 30, and a thermopile substrate 30 that protects the thermopile substrate 30. The drive motor 32 that rotationally drives the movable casing 31 to which is mounted, and the fixed casing 33 that has the drive motor 32 attached and fixed and has a window portion that covers the movable casing 31.
The thermopile 2 measures temperature with infrared rays from the object, and has a directivity characteristic as shown in FIG. 7 when sensing.
Therefore, in order to improve the sensing accuracy of the thermopile 2, it is important to capture the measurement object at the center of the sensor as much as possible. Therefore, the thermopile 2 is configured to move to center the measurement object.

As the drive motor 32, a stepping motor capable of detecting a position during rotation is suitable. However, when operating in the refrigerator, particularly in the environment of the freezing temperature range, it is necessary to consider icing due to inflow of humidity such as when the door of the refrigerator is opened and closed.
Therefore, a gear reduction mechanism may be provided between the output shaft of the drive motor 32 and the movable casing 31 in order to ensure a certain rotational output torque.
In addition, in order to suppress failure due to frost formation on the thermopile substrate 30, the thermopile substrate 30 is covered with a movable casing 31, and the movable casing 31 is further covered with a fixed casing 33 to ensure reliability. ing.
The casings 31 and 32 may be made of a general plastic material, but the window portion of the fixed casing 33 that receives infrared rays is preferably covered with a material that easily transmits infrared rays, such as silicon or polyethylene.

FIG. 8 shows the mounting position of the thermopile to the switching chamber, and FIG. 9 shows the detailed structure of the mounting position of the thermopile.
The thermopile 2 configured in this way is installed on the ceiling above the switching room 200 that is a room for measuring.
This is because if there is a switching case 201 for storing food in at least the switching chamber 20 that senses the thermopile 2, the food itself cannot be sensed unless it is installed above the height of the switching case 201.
In addition, when food or a human hand interferes with a mechanism part such as the drive motor 32 of the thermopile 2 when the door is opened or closed or when food is added, it also causes a problem.

Therefore, as shown in FIGS. 8 and 9, the fixing casing 33 of the thermopile 2 is attached with a screw 35 to a sensor mounting member 205 provided in a recess having a size that can be stored in the ceiling of the switching chamber 200 for sensing. Yes.
Furthermore, it is preferable to install the thermopile 2 in the vicinity of a region where the sensing accuracy is desired to be enhanced. The reason is that the closer the target food to the sensor, the higher the food occupancy rate in the field of view, which is not only advantageous, but also reduces the possibility of target food being put into blinds such as other foods. This is because that.
Therefore, for example, in the case of the first embodiment where warm food is usually placed in front of the switching case 201, the thermopile 2 is installed on the ceiling in front of the switching case 201 as shown in FIG. The system configuration is strong against disturbance.

Next, the structure of the switching room of the refrigerator-freezer for carrying out the frozen storage method according to Embodiment 1 of the present invention will be described with reference to FIGS.
This switching chamber 200 is based on the assumption that the switching case 201 is accommodated.
As shown in FIGS. 8 and 10, a front side cold air outlet 4 for actively sending cool air to the front side of the switching case 201 is provided on the front side of the ceiling of the switching room 200. On the rear side, a rear cold air outlet 5 is provided for actively sending cold air to the rear side of the switching case 201.
The front cold air outlet 4 communicates with a front damper 7 provided on the back side of the switching chamber 200 via an air passage 6 provided on the ceiling of the switching chamber 200. The rear cold air outlet 5 communicates with a rear damper 9 provided on the back side of the switching chamber 200 via an air passage 8 provided above the switching case 201. These front dampers 7 and 9 are connected to a cool air blowing path (not shown) for sending cool air.

  The reason why the front side cold air outlet 4 and the rear side cold air outlet 5 are provided in this way is that cold air can be sent intensively as shown by the arrow in accordance with the position where the food is placed. As shown in Fig. 2, the charged food can be quickly cooled. It should be noted that the thermopile 2 provided on the front side of the ceiling of the switching chamber 200 is moved and detected as to which point from the front side to the rear side the food is introduced.

  As shown in FIG. 5, the thermopile 2 is installed on the near side of the ceiling of the switching chamber 200, and the thermistor 3 for detecting the air temperature in the switching chamber 200 is installed on the back side of the switching chamber 200. When the temperature of the front side rises, such as when food is put in the front side of the switching case 201 of the chamber 200, the front side of the front side cold air outlet 4 is used to identify the temperature in the thermopile 2 and actively send cold air to the front side. When the temperature of the rear side rises, such as when the front damper 7 is opened and food is put into the rear side of the switching case 201, it can be identified by the thermopile 2, the thermistor 3, or the thermopile 2 This is because both the thermistor 3 and the thermistor 3 are distinguished from each other so that the rear side damper 9 of the rear side cold air outlet 5 is opened in order to actively send the cold air to the rear side.

As described above, the temperature unevenness in the switching chamber 200 caused by the input of food or the like can be recognized by the thermopile 2 or the thermistor 3 and the cold air can be distributed, so that unnecessary cooling in the switching chamber 200 can be prevented. it can.
In addition, when the thermopile 2 is not provided, food or the like in which cold air blown out from the rear cold air outlet 5 is thrown into the rear side even though there is an insufficient cooling portion in the switching chamber 200. By moving toward the rear side, only the surroundings of the thermistor that controls the inside temperature reach the set temperature locally, so the damper closes and the supply of cold air is stopped, but in this case the thermopile If 2 is provided, the temperature of the food etc. thrown into the front side can be known, so the damper can be closed and the supply of cold air can be prevented from being stopped, and the cooling performance and energy saving can be improved. it can.
By enabling such cold air distribution control, even if the food being fed is warm, it can be cooled intensively, so the temperature of the surrounding food is not raised excessively, and it is hygienic. And convenient. Even when the distance between the hot food and the frozen food becomes closer and the temperature of the frozen food is more likely to rise, adverse effects on the surrounding food can be minimized.

In the frozen storage method proposed in the present invention, it is necessary to achieve both rapid cooling and supercooled freezing, but these are conflicting cooling methods. Therefore, it is necessary to switch the control at an appropriate timing with an environment where compatibility is possible.
In order to bring food into a supercooled state, it is necessary to cool the food with a certain range of cooling capacity. This means that if the cooling capacity for cooling the food is too weak or too strong, the supercooling state does not occur or the supercooling state is released immediately.

When looking at the temperature history when the food is cooled, the cooling capacity when the temperature is clearly higher than the freezing point of the food has no particular effect on creating a supercooled state.
However, when the temperature is higher by several degrees C. (for example, 2 to 3 ° C.) than the freezing point of the food, it is necessary to weaken the cooling capacity, that is, to suppress the blowing of cold air onto the food surface.
The freezing point varies depending on the food, but it is in the range of 0 to -2 ° C for cooked rice. In order to make the whole food supercooled, it is necessary to make it supercooled on both the food surface side and the center part. However, considering the food cooling with low temperature cold air, the food surface side is cooled fast so it freezes first. However, the supercooling is released before the central portion becomes supercooled, and in this case, the central portion does not go through the supercooling state or the supercooling reached temperature. If it is high, the supercooling will be canceled and it will freeze.
Therefore, in order to stably overcool the entire food, it is necessary to reduce the temperature unevenness on the food surface layer side and the center part, and as a method for this, the cooling speed of the food surface is suppressed, That is, it is conceivable to suppress the blowing of cold air onto the food surface. However, when the temperature is higher than the freezing point of the food by several degrees Celsius (for example, 2 to 3 degrees Celsius), the temperature difference between the food surface layer side and the central portion is within 3 degrees Celsius, preferably within 2 degrees Celsius, more preferably within 1 degree Celsius. In particular, it is not necessary to weaken the cooling.

Next, the frozen storage method of Embodiment 1 of this invention is demonstrated based on the flowchart of FIG.
First, for example, when food is put in front of the switching case 201 in the switching chamber 220 (step S1) and the drawer door is closed, freezing control by the control device 16 is started (step S2), and the detected temperature of the thermopile 2 is detected. When the amount of change is calculated (step S3) and the calculated detected temperature is higher than room temperature (step S4), the front and rear dampers 7, 9 are opened to open the front cold air outlet 4 and the rear cold air. Cold air can be blown out from the outlet 5 to start rapid cooling (step S5).
The normal temperature here refers to a normally considered room temperature, for example, 15 to 35 ° C., and the high temperature refers to a temperature higher than the normal temperature, for example, 36 to 100 ° C., and the upper limit is a temperature considered as food.
The cooling rate in this rapid cooling is 0.5 ° C./min or more, preferably 0.7 ° C./min or more.
When the food surface temperature as the detection temperature of the thermopile 2 is 40 to 1 ° C., preferably 25 to 3 ° C., more preferably 10 to 5 ° C. (step S6), the rapid cooling is performed. Stop and start supercooling (step S7).
Since this overcooling needs to weaken the cooling capacity, in order to stop the rapid cooling at the predetermined temperature, the control device 16 first closes the front damper 7 and the rear damper that control the cooling air supply into the switching chamber 220. (Step S7a), the supply of cold air from the front and rear cold air outlets 4 and 5 is eliminated, and the cooling of the food is weakened.

  The temperature for starting the process of suppressing the supply of cold air, which is the first stage of the supercooling control, and making the temperature unevenness uniform is 40 to 1 ° C, preferably 25 to 3 ° C, more preferably 10 to 5 ° C. If it stops at a temperature higher than the predetermined temperature, there is no problem with supercooling freezing. . In addition, if the rapid cooling is stopped at a temperature lower than the predetermined temperature, the food surface will freeze first in the process of uniforming the temperature unevenness, etc., so that the supercooling state does not occur or the supercooling state becomes shallow. There is a possibility that the effect of improving the refrigeration quality due to freezing after overcooling will be lost or reduced.

When the supercooling is started, the control device 16 reaches a predetermined temperature that is several degrees Celsius (for example, 2 to 3 ° C.) higher than the freezing point near the freezing point of the food (Step S7b). The dampers 7 and 9 on the front side or the rear side or both the front side and the rear side are opened to increase the cooling capacity (step S7c).
That is, it is necessary to lower the food ambient temperature. When the freezing temperature is reached in a state where the temperature difference between the food surface layer side and the center portion is small, if the cooling capacity is too small, it will not be drawn into the supercooled state and will be frozen as it is.

Therefore, when the food temperature reaches near the freezing point, it is necessary to quickly cool it, but if cold cold air is blown strongly at this time, it may freeze from the food surface due to the factors described above. Therefore, caution is required for the cold air temperature. In addition, if the cold air temperature after being drawn into the supercooled state is too low, there is a high possibility that the supercooling will be canceled, and the air temperature in the case is set to -15 ° C or higher, or low temperature cold air is blown. It is necessary to prevent the food surface from being frozen by being exposed to low temperature and cold air for a long time, for example, by intermittently performing the above.
The time for increasing the cooling capacity in step S7c in this supercooling is roughly 100 to 600 minutes depending on the amount of food to be added, and when the predetermined time has elapsed (step S7d), rapid cooling starts again ( Step S8), for example, when a predetermined time of 60 to 120 minutes elapses (Step S9), the rapid cooling is stopped, the temperature is returned to a normal freezing initial set temperature, for example, −7 ° C., and normal frozen storage is performed (Step S10). ).

  Thus, as in step S7c, after the food temperature reaches a sufficient supercooling arrival temperature, the supercooling is released and frozen, but in this case, the cooling capacity is increased, that is, the food is actively cooled at low temperature. It is necessary to spray. Increasing the cooling capacity not only cancels supercooling, but also shortens the time until it completely freezes after canceling supercooling, thereby suppressing ice crystal enlargement and reducing food damage due to freezing. The

Further, when the cooling capacity is weakened like the supercooling in step 7a, the front and rear dampers 7, 9 are closed, or the time during which these dampers 7, 9 are closed can be lengthened to suppress the inflow of cold air. That's fine.
In addition, in the case where the cooling capacity in such supercooling is weakened, in the stage where the cold air should not be directly blown, the one near the food input position, that is, the blowout outlet of the one where the blown cold air is likely to hit the food. It is only necessary to close the damper and cool only with the cool air sent from the other outlet. In addition, when it is necessary to positively spray low-temperature cold air on the food as in the case of rapid cooling as in step 5, the blower that is closer to the food input position, that is, the air that is blown out easily hits the food. Open the mouth damper or open all the dampers and send in cold air.

  In the cryopreservation method of the first embodiment, the method of freezing the warm food after rapid cooling has been described, but the input food is not a warm food but a cold food at room temperature or less, which is unfrozen. Even in such a case, as shown in FIG. 11, it is possible to perform only the supercooling control by skipping the rapid cooling process in step S5.

Embodiment 2. FIG.
FIG. 12 is a perspective view showing a switching case of a refrigerator-freezer for carrying out the frozen storage method according to Embodiment 2 of the present invention, and FIG. 13 is a perspective view showing another switching case of the refrigerator-freezer for carrying out the frozen storage method. .
In the first embodiment, the refrigeration control proposed in the present invention is enabled in the entire switching case 201 accommodated in the switching chamber 200. However, in the second embodiment, the switching case accommodated in the switching chamber 200 is used. The refrigeration control proposed in the present invention is performed only in 201 specific sections.
Among the switching cases 201 accommodated in the switching chamber 200, the advantage of performing the freezing control of the present invention only in a specific section is that the position where the warm food is put in is specified, so that the opportunity to contact the frozen food It is a point that can be reduced, and more accurate control is possible in a narrow section.

As shown in FIG. 12, on the front side of the switching case 201, a tray 1 serving as a food input space such as cooked rice is installed.
The reason why the tray 1 is provided at the front side position of the switching case 201 as shown in FIG. 12 is that, for example, when the cooked rice is put in a warm state, it may be placed on the front side considering that frozen food is already stored. This is because it is expensive and it is more convenient to place it on the top of the case, considering the creation of new space for cooked rice.
The tray 1 is made of aluminum or plastic. In the case of an aluminum tray, heat conduction is good and the temperature distribution tends to be uniform, which is effective for cooling cooked rice.
In addition, the tray 1 may contain a cool storage agent, and in this case, a heat insulating effect can be obtained. Therefore, even if hot rice is put on the frozen storage food and cooled, the frozen food is adversely affected. Absent.

Further, the tray 1 has shafts 1 a at both ends, and these shafts 1 a are rotatably supported on the front sides of the inner surfaces of both side walls of the switching case 201 and are rotatably attached to the switching case 201.
When the tray 1 is used, the rear end of one side of the tray 1 is placed on the rib 41 and becomes horizontal and can be used. When the tray 1 is not used, the tray 1 is rotated in a vertical state, and a recess (not shown) provided on the other end side of the tray 1 is provided in a claw (not shown) provided at the upper end of the front opening of the switching case 201. The tray 1 is folded so as to be hooked, so that it does not interfere with other food storage.

In addition, the tray 1 may not be folded as shown in FIG. 12, but may be placed on the four ribs 41 provided in the switching case 201 and stabilized as shown in FIG.
In this case, if a plurality of places where the ribs 41 are provided, the layout can be changed according to the use situation such as the front, center, and rear of the switching case 201. Moreover, when providing the rib 41, if the height location which is different also in a height direction is made into multiple, it is possible to lay out the height of the tray 1 freely according to the quantity of the existing food and the rice to be frozen.
In the structure shown in FIG. 13, when the tray 1 is not used, the tray 1 can be stood and stored in the tray pocket 20 on the front surface of the switching case 201 and does not interfere with other foods.

  Up to now, the switching chamber has been described as an example of implementing the refrigeration method proposed in the present invention, but the same applies to the freezing chamber.

As mentioned above, although the freezing method which improves the quality of cooked rice has been described, there is an example in which the quality is improved even if other foods are frozen using this method, and the frozen storage method of the present invention is applied only to cooked rice. It shouldn't be.
For example, in foods containing starch and water, such as hot cakes and breads, results of improving the quality in the freezing method of the present invention have been obtained by experiments.
Therefore, using the refrigeration method of the present invention and obtaining a refrigerator capable of realizing the refrigeration method of the present invention has a wide range of applications for improving food storage stability, and can be widely developed including commercial refrigerators.

The schematic diagram which shows the difference between the freezing method of the cooked rice in the frozen preservation method of the foodstuff of Embodiment 1 of this invention, and the conventional frozen method of cooked rice. The graph which shows the texture of the cooked rice frozen by the freezing preservation method. The graph which showed the temperature change when water freezes without supercooling (a) and with supercooling (b). Side surface sectional drawing of the refrigerator-freezer which enforces the freezing preservation method. Side surface sectional drawing which shows the switching chamber of the freezer refrigerator which enforces the same cryopreservation method. The disassembled perspective view of the infrared sensor of the refrigerator-freezer which enforces the same cryopreservation method. The graph which shows the directional characteristic of the infrared sensor of the refrigerator-freezer which enforces the freezing preservation method. Side surface sectional drawing which shows the switching chamber of the freezer refrigerator which enforces the same cryopreservation method. The perspective view which shows the sensor attachment part periphery of the switching chamber of the freezer refrigerator which enforces the freezing preservation method. The perspective view which shows the switching case of the freezer refrigerator which enforces the freezing preservation method. The flowchart which shows the example of the supercooling control of the frozen storage method. The perspective view which shows the switching case of the refrigerator refrigerator which enforces the frozen preservation method of Embodiment 2 of this invention. The perspective view which shows another switching case of the freezer refrigerator which enforces the same cryopreservation method.

Explanation of symbols

1 tray, 2 thermopile, 3 thermistor, 4 front air outlet, 5
Rear air outlet, 7 front damper, 9 rear damper, 10 operation panel, 16 control device, 100 refrigeration room, 200 switching room, 201 switching case, 300 vegetable room, 400 freezing room, 500 ice making room.

Claims (4)

A freezer room that can be set in a freezing temperature zone and has a rapid cooling function;
A case for storing food installed in the freezer compartment;
A temperature sensor capable of recognizing a high temperature food temperature and a food input position in the case;
At least two cold air outlets for blowing cold air into the case;
Damper means for controlling the feed of cold air to these cold air outlets,
A refrigerator-freezer that performs a method for freezing and storing foods by storing the food containing starch such as cooked rice by controlling the damper means based on the temperature detected by the temperature sensor ,
The frozen storage method of the food,
When the food temperature is high , cool air is intensively blown out from the cold air outlet close to the food charging position, and rapidly cooled at a cooling rate of 0.5 ° C./min or more,
Thereafter, when the food surface temperature reaches a temperature range of 40 to 1 ° C., the rapid cooling is stopped to weaken the cooling capacity, and the cold air is blown out from the cold air outlet other than the cold air outlet close to the food charging position,
After that, when the food temperature reaches near the freezing point temperature, the food ambient air temperature is cooled with cold air in a range that does not fall below -15 ° C.
After a predetermined time has elapsed, quick cooling is performed to release the supercooling of the supercooled food,
Thereafter, refrigerator, characterized in that performs a normal frozen. The temperature sensor, refrigerator according to claim 1, characterized in that the thermopile variable Doshiki. The refrigerator-freezer according to claim 1 or 2, wherein a tray that forms a space in which high-temperature food can be placed is detachably installed in the case. 4. The refrigerator-freezer according to claim 3, wherein the tray is configured with a member that promotes cooling of the warm food or prevents heat of the warm food from being transmitted to the frozen food.

Images