JP2009228966A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerator capable of maintaining freezing quality the same as or higher than that of a fresh agricultural product blanched and frozen even when the fresh agricultural product such as a vegetable is frozen in a freezing compartment without a blanching treatment. <P>SOLUTION: This refrigerator includes a freezing cooler, an auxiliary freezing compartment into which cold air generated in the freezing cooler is introduced and which is cooled and maintained at a prescribed temperature, a fan for blowing cold air to the auxiliary freezing compartment, and a temperature control device for controlling the temperature of the auxiliary freezing compartment. In the case of storing a fresh agricultural produce in the freezing compartment, the cooling speed in the freezing compartment is made mild on freezing the fresh agricultural product, and thereafter, the temperature is lowered to a prescribed temperature and the fresh agricultural produce is frozen and stored. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigerator that can be stored for a long time by storing fresh produce such as vegetables in a frozen state.

  Conventionally, when fresh produce such as vegetables is frozen and preserved for a long period of time to maintain its freshness, it is about 75 to 80% light in the manufacturing process as a frozen food and in home freezing at home. It was often frozen after pretreatment such as so-called blanching, in which heat treatment is performed for sterilization and moisture reduction. This is due to the following two reasons.

  (1) Since agricultural products are plant bodies, their cells have tough cell walls. Therefore, when frozen in a state where the moisture in the cells is sufficient, such as when the vegetables are fresh and fresh, ice crystals grow and freeze. Cell swelling and tissue damage occurs due to swelling, and nutrients and taste components are lost as a drip and the texture deteriorates. In addition to reducing, the cell wall is softened by heat treatment, and the tissue damage due to freezing is comprehensively reduced.

  (2) Agricultural products are living organisms and include various enzymes. Some of these enzymes are active even at freezing temperatures. Oxidative discoloration (browning) such as chlorophylls, carotenoids, anthocyanins, and phenols, and oxidation of vitamin C and enzymatic action, such as aldehydes, alcohols, and hexanals The enzyme is composed of protein and can be denatured and deactivated by heat treatment, etc., so that the enzyme is heat-inactivated beforehand by blanching or the like. Prevents degradation reactions caused by enzymes during frozen storage.

  However, blanching treatment is widely used as a production process for frozen agricultural products on a commercial basis because of its effectiveness, but in ordinary households, it is less frequently implemented than home freezing of fresh meat or rice and tends to be avoided.

  This is done by boiled and fried, except when the process of removing moisture to boil the frozen produce is cooled to room temperature or when the frozen produce is frozen or frozen. It is common to raise the temperature up to around 100 ° C., such as boiled, and cook it by thawing, and since it is heated twice together with blanching, the nutritional components, taste, aroma, etc. of the agricultural products are easily impaired. That is, it is thought that it originates in the unsatisfactory point that it cannot eat deliciously even if it freezes taking time.

  The present invention has been made paying attention to the above problem, and even if fresh produce such as vegetables is frozen in a freezer without performing a blanching treatment, it is equivalent to an agricultural product that has been blanched and frozen, or It aims at providing the refrigerator which enabled it to maintain the frozen quality beyond it.

  In order to solve the above-described problems, a refrigerator according to the present invention includes a refrigeration cooler, a freezing room that is cooled and held at a predetermined temperature by introducing cold air generated by the freezing cooler, and cool air to the freezing room. It consists of a fan that blows air and a temperature control device that controls the temperature of the freezer compartment. When fresh produce is stored in the freezer compartment, the fresh produce is frozen by slowing the cooling rate in the freezer compartment and then reaching a predetermined temperature. It is characterized by being stored at a low temperature and frozen.

  According to the configuration of the present invention, the fresh produce stored in the freezer room can be stored for a long time by freezing without requiring troublesome work, as well as suppressing nutrient destruction and taste, It can be eaten deliciously while keeping the fragrance and the like intact.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The refrigerator main body (1) whose front view is shown in FIG. 1 and whose longitudinal cross-sectional view is shown in FIG. 2 is filled with a foam insulation (4) between the outer box (2) and the inner box (3). The storage compartment is partitioned into an upper refrigeration compartment (6) and a lower refrigeration compartment (7) by a heat insulating compartment wall (5), and the front opening of the refrigeration compartment (6) is closed by a double door. In addition, the upper part of the inside is a refrigerated storage room (8) provided with a plurality of mounting shelves, and the lower part thereof is partitioned by a partition plate (9) that also serves as a shelf made of transparent resin, thereby forming an independent space, A drawer-type vegetable container (11) is placed inside the vegetable compartment (10), and at the bottom of the refrigerator compartment (6) is a partition plate that similarly forms the bottom of the vegetable compartment (10). A low temperature chamber (13) for cooling the room to about 0 to -3 ° C is provided through (12).

  As for the freezing space (7), an ice making room (14) provided with an automatic ice making device having a relatively small volume immediately below the heat insulating partition wall (5) and an auxiliary freezing room provided to store fresh produce in a frozen state (14). 15) together with the doors provided in the front openings, and the lower part of the main freezer compartment (16) is a drawer type as described above, and the upper and lower drawer type containers (17a) (17b) ).

  Refrigerating and freezing coolers (18) and (19) and fans (20) and (21) corresponding to the respective coolers are arranged on the back surfaces of the refrigerator compartment (6) and the freezing space (7), respectively. The cool air generated by the coolers (18) and (19) is introduced into the respective storage chambers via the ducts by the fans (20) and (21) and cooled.

  The refrigeration and refrigeration coolers (18) and (19) are configured as a part of the refrigeration cycle (22) shown in FIG. 3, and from the discharge side of the compressor (23) provided at the lower part of the refrigerator body (1). The condenser (24) and the three-way valve (25) for switching the refrigerant flow path are connected in order, and the refrigeration side capillary tube (26) and the refrigeration cooler (18) are in series on one side of the three-way valve (25). So that they are connected. On the other side of the three-way valve (25), a refrigeration side capillary tube (27) and a refrigeration cooler (19) are connected in series, and the outlet side of the refrigeration cooler (19) and the compressor (23) suction The side is connected. The outlet side of the refrigeration cooler (18) is connected between the outlet side of the freezing side capillary tube (27) and the inlet side of the freezing cooler (19).

  The three-way valve (25) is controlled to switch the flow direction of the refrigerant according to the signal from the control device, and to cool it by flowing the refrigerant alternately to the refrigeration cooler (18) side or the refrigeration cooler (19) side. In the case of refrigeration operation, when the refrigerant is caused to flow to the refrigeration cooler (18) side by the three-way valve (25), the refrigerant flowing through the refrigeration cycle is mainly evaporated in the refrigeration cooler (18), The cold air, which has been reduced in temperature by heat exchange, is discharged into the refrigerator compartment (6) by the fan (20), thereby cooling the refrigerator storage compartment (8) and the vegetable compartment (10) to an appropriate temperature. In addition, circulating cold air from the refrigerator compartment (6) and a part of the cold air from the refrigerator (22) are directly introduced into the low temperature chamber (13) and cooled to a lower temperature than in the upper refrigerator compartment (6). To do.

  In the refrigeration operation, the refrigerant is directly introduced into the refrigeration cooler (19), evaporates at a low evaporation temperature, and cool air that has become low temperature due to heat exchange is cooled in the refrigeration space (7) by the fan (21). It introduces into a freezer compartment (16), an auxiliary freezer compartment (15), an ice making room (14), etc., and it controls to cool each room to predetermined freezing temperature by forced circulation.

  The control device compares the temperature in the refrigerator compartment (6) with the temperature mainly in the freezer compartment (16) and operates the compressor (23) and the fans (20) (21). In addition, switching between the refrigeration operation and the freezing operation is performed by changing the room temperature during cooling to a predetermined temperature, for example, the sensor temperature for detecting the temperature of the refrigeration room (6) reaches 0 ° C. or lower, When the sensor detects −20 ° C. or lower, or when the cooling operation time is a predetermined time, for example, 15 to 20 minutes for refrigeration operation, 30 to 40 minutes for freezing operation, the three-way valve (25) is operated. Switch to the other cooling operation.

  Thus, the auxiliary freezer compartment (15) is cooled by directly introducing the cold air from the freezer cooler (19) into the room, and in the vicinity of the cold air outlet (28), A temperature control device for the auxiliary freezer compartment (15), which is equipped with a cold air damper (29) that adjusts the amount of cold air into the room. The cold air damper (29) is rotated by pressing a start button (not shown) which is provided on an operation panel such as the front of the door and is arbitrarily operated, and closes the outlet (28) to the auxiliary freezer compartment (15). This is to block the cold air blowout.

  When the start button is pressed and the outlet (28) is closed, the auxiliary freezer compartment (15) is cooled only by heat leakage from the surrounding freezing space, so the relationship between the freezing speed and the indoor temperature drop As shown in FIG. 4, which is a graph comparing the conventional temperature and the conventional temperature, the temperature drop time becomes slow, and the input fresh crop reaches the freezing point about 60 minutes after the start button is pressed, and then the freezing point temperature until the freezing is completed. Transition. When the freezing is completed, the temperature drops and passes through the maximum ice crystal formation zone. During this time, the temperature gradually drops, and the cooling operation is finished in about 180 minutes (3 hours) after reaching the freezing point. Become.

  Regarding the temperature drop due to heat leakage in the auxiliary freezer compartment (15), it is necessary to consider the surrounding heat insulating material and heat insulation wall thickness, etc., and the temperature drop takes about 240 minutes (4 hours) after pressing the start button. As a result, fresh crops are gradually cooled to a frozen state (hereinafter referred to as “slow freezing”), but if the amount of agricultural products to be frozen is large or the amount of heat leakage alone, the crops may not be frozen. In such a case, for example, by detecting the return air temperature of the auxiliary freezer compartment (15), if the detected temperature is equal to or higher than the predetermined temperature, the cold air damper (29) is opened to increase the amount of cold air On the other hand, if the temperature is equal to or lower than the predetermined temperature, the control is performed so as to be closed so as to cool to a temperature corresponding to the slow freezing.

  In addition, the cool air damper (29) is rotated by a stepping motor and rotated according to the set temperature corresponding to the type of fresh produce, and the air flow into the room is changed by changing the opening of the air outlet (28). The freezing speed may be slowed by adjusting the cooling power by changing the amount or temporarily stopping the blowing by the fan (21).

  After performing the refrigeration operation control by such gentle cooling for a predetermined time after pressing the start button, for example, 240 minutes, the damper (29) is opened to return to the refrigeration operation, and at a lower temperature. Perform frozen storage.

  As described above, fresh agricultural products frozen by a slow freezing operation were compared with those rapidly frozen using grapes and apples as examples.

  In general, if it passes through the maximum ice crystal formation zone (0 to -5 ° C) over a long period of time, the ice crystals will grow and the cell tissue will be destroyed. If it passes within 30 minutes, the moisture in the cells will not become large crystals and will not destroy the food tissue. However, as a result of the above-described experiment, the rapidly frozen grapes had a large tissue destruction due to freezing and expansion, and the so-called cracking occurred in which the pulp part was largely torn. Moreover, when rapidly frozen apples were crushed and squeezed after thawing, they were easy to smash and the amount of squeezed was large. On the other hand, grapes by slow freezing were not broken and apples were hardly squeezed.

  From these, unlike the case of fish meat, quick freezing treatment for agricultural products such as fresh vegetables is inappropriate as freezing treatment because of the damage to cell tissues, and slow freezing is better. Can be judged.

  In addition, cold air introduction into the cooling auxiliary freezer room (15) is configured to control the cold air damper (29) by the stepping motor, and the room temperature is set to a freezing temperature, a chilled temperature, a refrigerator temperature, a temperature suitable for wine cooling, etc. As a configuration with a temperature switching room that can be set to an arbitrary temperature, when storing fresh produce, set the indoor temperature setting to about -12 to higher than the normal freezing temperature of -17 to -18 ° C, This may be continued for a predetermined time, for example, 240 minutes.

  According to this configuration, since the inside of the auxiliary freezer compartment (15) is cooled at a temperature higher than the normal freezing temperature, the time until the stored storage item is frozen is inevitably longer, and more gradual refrigeration control is more reliably performed. realizable.

  Regarding each of the slow freezing, as another cooling mode, when the start button is pressed, normal freezing cooling is performed with the cold air damper (29) opened for a predetermined time, for example, 30 minutes. Later, the cool air damper (29) may be closed to restrict the supply of cool air into the auxiliary freezer compartment (15), or the set cooling temperature may be increased to perform a slow freezing operation with a slow freezing speed.

  This is because until the object to be frozen reaches the freezing point, it is preferable that the cooling time is short from the viewpoint of hygiene and shortening the freezing time, and when the freezing operation by gentle cooling is completed. Move to freezing operation at low temperature.

  Then, when the freezing of the fresh produce is completed by the above-described slow freezing control, the three-way valve (25) of the refrigeration cycle (22) or the capillary for freezing (27) With the squeezing control, the room temperature of the auxiliary freezer compartment (15) is lowered to −23 ° C., which is lower than the normal freezing cooling temperature, and the fresh produce is stored frozen under this low temperature operating condition.

  In this way, frozen storage after slow freezing can be performed at a lower freezing temperature, thereby suppressing deterioration of the components of fresh produce due to enzymatic reactions during storage and destruction of cell tissues due to the growth of ice crystals. Can maintain good quality.

  In the freezing operation at a low temperature after the slow freezing operation, propane having a low boiling point of −42 ° C. or the like is used as a refrigerant, and a deep temperature freezing operation at a lower temperature of −30 ° C. or lower is performed. However, it is possible to store for a long period of time while maintaining the freshness by freezing at a lower temperature.

  In each of the above examples, the sample was gently frozen for 240 to 300 minutes (4 to 5 hours) without blanching, frozen at -18 ° C and -30 ° C after freezing, and the same as described above after blanching. Each of the quick-frozen foods was stored for 4 weeks, then boiled and thawed, and the appearance and taste were compared and confirmed. Fresh agricultural products used in the experiment were broccoli, sweet bean, cabbage, radish, potato, burdock, sweet potato, asparagus, pumpkin, carrot and spinach, each with 90 grams of ziplock packaging.

  The result is as shown in FIG. 5, and the one that was frozen and stored at a low temperature of −30 ° C. after blanching kept the best state, but was frozen at −18 ° C. after slow freezing without blanching. Other than pumpkin and asparagus, the food was discolored and the taste was deteriorated, making it unsuitable for eating.

  And what was frozen at −30 ° C. after gradual freezing without blanching is equivalent to or higher than that of boiled and then rapidly frozen and then stored at −18 ° C., except for spinach. It was the quality that kept the appearance and taste.

  Among them, radish, potato, and carrot were frozen slowly over 240 minutes without branching, and then frozen at -30 ° C., and then rapidly frozen after conventional blanching. It was better than those stored at ℃ and -30 ℃, and the amount of drip efflux after thawing was also halved compared to that by conventional quick freezing. In particular, Japanese radish and potato obtained an excellent evaluation in terms of texture close to that of fresh products than those frozen at −30 ° C. after blanching.

  The slow freezing time is appropriately 240 to 300 minutes (4 to 5 hours), and if it is too long, such as 420 minutes (7 hours) or more, the change in the structure of the article to be frozen becomes unsuitable. is there.

  With regard to the above, in the case of Japanese radish, voids in the tissue are buried by blanching, and it is considered that starch is heated and gelatinized to adversely affect freezing resistance. For potatoes, freezing slowly without blanching and then storing frozen at a low temperature is an excellent freezing method.

  The deliciousness retention period is longer as the storage temperature is lower. According to the applicant's experiment, it is 7 to 10 days at −18 ° C. and 2 to 3 weeks at −23 ° C., but after slow freezing − When stored frozen in an atmosphere of 30 ° C., it can retain its taste for 4 to 6 weeks, and when stored frozen at −40 ° C., it can maintain quality for a longer period of time. It was.

  In addition, the change in the amount of drip at the time of thawing when the freezing speed was changed without blanching was investigated for raw cut radish. The result is as shown in FIG. 6, and the freezing time is the largest when the amount of drip is around 80 to 170 minutes, depending on whether it is quick freezing of 80 minutes or less or slow freezing over 170 minutes for freezing. It can be seen that loss due to drip outflow can be suppressed.

  From this, it can be said that slow freezing is superior in cost to quick freezing, which requires a high-performance freezing apparatus or consumes a large amount of energy during freezing. However, even in the case of slow freezing, for example, in the case of the maximum time of 570 minutes in the figure, the amount of drip is reduced, but the structure of the radish hardens and causes a bad effect on the texture. Time is inappropriate in terms of taste.

  As for the above, in addition to cut radish, raw cut potatoes and carrots also have the same experimental result that drip loss is reduced with a gentle freezing time of around 180 minutes. As the freezing time considering both the drip suppression and the texture retention, it can be determined that the slow freezing time of 180 to 300 minutes (3 to 5 hours) is appropriate.

  In addition, fresh agricultural products that have been gently frozen without blanching and those that have been rapidly frozen after conventional blanching are stored at various freezing temperatures for 5 weeks, and then boiled and thawed. The amount was measured for broccoli, radish, potato, cabbage and the like.

  As a result, the lower the frozen storage temperature of −30 ° C. or −40 ° C., the higher the degree of vitamin C retention, and the one that is slowly frozen raw without blanching is the vitamin C retention degree. There was a high tendency.

  Next, according to the present invention, that is, the taste evaluation results of the fresh agricultural products, which were frozen slowly in a raw state without blanching, frozen at -30 ° C. for 6 weeks, and boiled and thawed, were evaluated in the same manner as in FIG. ◎ Shown in FIG. Among the 36 types of agricultural products that were evaluated, × evaluations consisted mainly of vegetables with strong lye (Komatsuna, taro, Chinese yam, eggplant, spinach) and vegetables with large cells and high water content (onion, Chinese cabbage). By avoiding agricultural products having characteristics, the refrigerator of the present invention can effectively perform frozen storage of fresh agricultural products.

  As described above, according to the embodiment of the present invention, it is possible to eliminate the troublesome work of cooling to the room temperature after branching the agricultural product to be frozen, and by gradual freezing without performing branching. In addition to suppressing tissue damage, it can eliminate the problems of damaging nutrient components, taste, and fragrance by heating twice by blanching other than during cooking, and subsequent low-temperature freezing suppresses component deterioration during frozen storage In addition, it can maintain the freshness quality including appearance and taste equivalent to or faster than the conventional freezing after blanching, enabling the frozen storage of fresh produce over a long period of time and eating deliciously. .

  Since it is better to change the cooling rate and time during the gradual freezing according to the type of agricultural products, it is preferable that the cooling rate and time can be arbitrarily set. When this is stored, the cooler damper (29) is automatically rotated to close the air outlet (28) or change the opening of the opening. Also good.

It is a front view of the refrigerator which shows one Embodiment of this invention. It is a longitudinal cross-sectional view of FIG. It is the schematic which shows the refrigerating cycle of the refrigerator of FIG. It is a comparison graph of slow freezing and the conventional freezing speed. It is the quality comparison data of the fresh produce after frozen storage by this invention, and a conventional system. It is a change graph of the drip amount at the time of thawing | decompression at the time of changing the freezing speed of this invention. It is the taste evaluation of the fresh agricultural products which were frozen, stored frozen and thawed according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerator body 5 Insulation division wall 6 Refrigerated room 7 Refrigerated space 8 Refrigerated storage room 10 Vegetable room
13 Low greenhouse 14 Ice making room 15 Auxiliary freezer room
16 Freezer 18 Refrigerator 19 Refrigerator
20 Refrigeration fan 21 Refrigeration fan 22 Refrigeration cycle
25 Three-way valve 28 Air outlet 29 Cold air damper

Claims (7)

  A freezer cooler, a freezer compartment that is cooled and held at a predetermined temperature by introducing cold air generated by the freezer cooler, a fan that blows cool air to the freezer compartment, and a temperature that controls the freezer temperature When the fresh produce is stored in the freezer compartment, the cooling rate in the freezer compartment is slowed to freeze the fresh produce, and then the temperature is lowered to a predetermined temperature and stored frozen. Refrigerator.   2. The refrigerator according to claim 1, wherein when the fresh produce is stored in the freezer compartment, the time required from the start of the freezing operation to the completion of the freezing is 180 minutes or more.   The refrigerator according to claim 1 or 2, wherein when fresh produce is stored in the freezer compartment, the introduction of cold air into the freezer compartment is stopped or reduced for a certain period of time after storage.   The refrigerator according to claim 1 or 2, wherein when fresh produce is stored in the freezer compartment, the cooling set temperature of the freezer compartment is higher than normal.   The refrigerator according to claim 3 or 4, wherein when fresh produce is stored in the freezer compartment, the cooling rate in the freezer compartment is moderated after cooling to a predetermined time or a predetermined temperature.   The refrigerator according to any one of claims 1 to 5, wherein the fresh produce stored in the freezer is cooled at a moderate rate and then frozen and stored at a low temperature of -30 ° C or lower.   The refrigerator according to claim 6, wherein propane is used as the refrigerant.

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