JP5939277B2 - Refrigeration method and refrigeration apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for freezing various objects to be cooled, such as biological tissues, food materials and processed products, and fresh food products.

Conventionally, biological tissues, various materials and processed products, and fresh food products have been stored by freezing or refrigeration means, especially while maintaining the freshness of biological tissues, fresh materials, fresh food products, etc. A refrigeration method is frequently used as a method for enabling long-term storage. As a freezing method for such biological tissues, fresh materials, fresh foods, etc., a linked freezer is used, and an object to be cooled (food) is placed on a belt conveyor or a net conveyor in the linked freezer. A refrigeration system that continuously introduces and transfers to a cooling zone in the apparatus and cools biological tissues, fresh materials, fresh food products, and the like has been adopted (for example, Patent Document 1). In general, an object to be cooled is frozen by blowing a cold air having a constant temperature of about −45 to −35 ° C. onto a product using a continuous freezing apparatus.
In the case of a to-be-cooled object that has a particularly high moisture content among fresh foods, if the object to be cooled is frozen by blowing cold air at a constant temperature of about −45 to −35 ° C. as described above, Freezing of the object to be cooled starting from the surface side becomes too fast, and it becomes impossible to absorb the increase in volume caused by the phase change of the moisture content that occurs near the center of the object to be cooled. The surface side may receive a strong stress from the inside, and the object to be cooled may be broken or broken. Fresh scallops are a typical example of a fresh food product with particularly high water content and destruction, and may cause convex deformation or cracking from the inside to the outside during freezing. Deformation and cracking of fresh food products will significantly reduce the value of the product, so cool air at around −45 to −35 ° C. is applied to the fresh scallop at the initial cooling stage to slow freezing. Such a freezing process may be used.

On the other hand, to-be-cooled objects such as foodstuffs, foods and living bodies include bound water bound by their constituent molecules and free water that can move freely within the to-be-cooled object without being bound by molecules. The free water is frozen during freezing, which leads to the growth of ice crystals. The growth of ice crystals in the tissue of the object to be frozen promotes the destruction of the cells and tissues. When the cells and tissues are destroyed, the texture and taste of foods and foods are deteriorated, and the commercial value is significantly reduced. Will do. It has become clear that such ice crystal coarsening occurs when the time for passing through the ice crystal generation temperature range is slow during freezing.
In response to these problems related to the growth of ice crystals, when holding various fresh materials by freezing or refrigeration, the low temperature object is mixed with substances such as a gelling agent and a freezing point lowering effect. And the technique which suppresses the growth of the ice crystal in a structure | tissue is disclosed (for example, patent document 2). In this method, various substances are added to a low-temperature object to be gelled and then stored at a low temperature to suppress the growth of ice crystals in the tissue and prevent the destruction of cells and tissues.

Japanese Patent Laid-Open No. 2001-120243 (page 4, FIG. 1) Japanese Patent Laid-Open No. 5-76332 (page 2, FIG. 1)

  However, when the method of Patent Document 2 is used as a means for suppressing the growth of ice crystals in the tissue, it is possible to suppress the growth of ice crystals in the tissue, but food, food, living bodies, etc. to be frozen. It is necessary to mix various substances having an action suitable for an object, which complicates the freezing process and is difficult to use in practice. Therefore, a method is conceivable in which the cold air temperature is lowered to, for example, −55 ° C. to −50 ° C. with respect to the object to be frozen, and the cooling rate (freezing rate) is further increased to suppress the ice crystal coarsening. However, depending on the object to be frozen, in the method of rapid cooling by blowing cold air lowered to −55 ° C. to −50 ° C., moisture present inside becomes ice on the surface, and heat transfer to the inside is hindered. Since the cooling is delayed, there is a problem that the cooling efficiency is lowered due to a large energy loss of a refrigerator or the like in addition to the harmful effect of the coarsening of the ice layer near the surface.

  In addition, as described above, for fresh foods that have a risk of convex deformation or cracking from the inside to the outside during freezing, cool air of about −45 to −35 ° C. is applied at the initial cooling stage. There is a measure to slow down and apply it to fresh foods to slow the freezing and allow the volume change during the freezing process to escape to the outside. However, since the average cooling rate is slowed, the productivity is significantly reduced.

  The present invention has been made paying attention to the problem of cooling efficiency derived from temperature management and temperature management appropriately selected according to the above-mentioned conflicting characteristics of the object to be cooled and the characteristics of the cooling stage. When freezing various objects to be cooled, such as raw materials, processed products, and fresh food products, the deformation and cracking of these objects to be cooled are prevented and the destruction of tissues and cells inherent to the objects to be cooled is minimized. It is an object of the present invention to provide a refrigeration method and a refrigeration apparatus that can be refrigerated without lowering productivity and energy efficiency as compared with the prior art.

In order to solve the above problems, the refrigeration method of the present invention comprises:
In a refrigeration method for cooling and freezing an object to be cooled continuously introduced and transferred without causing a supercooled state by a plurality of cooling steps,
The cooling process includes at least an initial first cooling process and a second cooling process after the first cooling process, and the cold air temperature used in each cooling process is set to a constant temperature,
The first cooling step using the first cold air temperature continues until the temperature of the object to be continuously introduced and transferred reaches the vicinity of the freezing temperature, and uses the second cold air temperature lower than the first cold air temperature. It is characterized by shifting to two cooling processes.
According to this feature, if the cooling temperature used in the initial cooling process is relatively high, it is possible to delay freezing of the object to be cooled starting from the outer surface side of the object to be cooled, and near the center of the object to be cooled. Absorbing the increase in volume, that is, the volume change during the freezing process can easily escape to the outside, and the object to be cooled can be prevented from being broken. In the subsequent cooling step, it is possible to reliably suppress the coarsening of the ice crystals by increasing the freezing speed by cooling the object to be cooled at a lower cold air temperature. By applying such temperature control, it is possible to prevent deformation and cracking of the object to be cooled and to prevent destruction of tissues and cells inherent to the object to be cooled as much as possible, and loss of cooling energy in the initial stage of the cooling process. Even if the cold air temperature is lowered in the subsequent cooling process, there is no significant energy loss of the refrigerator, etc. as a total of the entire process, and efficient refrigeration processing can be performed without lowering productivity than before. It becomes possible. Furthermore, the freezing of the object to be cooled starting from the outer surface side of the object to be cooled can be sufficiently delayed, and the time for the volume change in the freezing process to escape to the outside can be secured.

Cold air temperature for cooling the object to be cooled before Symbol cooling step is characterized in that it is adapted to decrease stepwise.
According to this feature, the nature of the tissues and cells inherent to each object to be cooled differs, and the appropriate cooling rate varies depending on the characteristics of each object to be cooled and the characteristics of the cooling stage, and each of them requires optimal temperature management. However, optimum temperature management is possible by adjusting the time in each process.

The refrigeration method of the present invention comprises:
A first cooling area that is provided in a freezing device and that performs at least the first cooling process; a second cooling area that performs the second cooling process; and a refrigerator that is disposed in each cooling area and that can control supply of cold air. It is characterized in Rukoto using a refrigeration apparatus comprising a conveyor for continuously introducing transfer the object to be cooled to each of the cooling area, the.
According to this feature, it is possible to efficiently manufacture a large amount of objects to be cooled without deformation or cracking using a refrigeration apparatus.

The refrigeration method of the present invention comprises:
The first cold air temperature is set to a range of −15 ± 5 ° C., and the second cold air temperature is set to −44 ° C. or lower .
According to this feature, the first cooling step in which the first cold air temperature is set to −15 ± 5 ° C. sufficiently delays the freezing of the object to be cooled starting from the outer surface side of the object to be cooled, thereby coarsening the ice crystals. Since the passage time of the ice crystal generation temperature range that may be incurred can be shortened, a series of refrigeration processes without causing a large energy loss even if the cold air temperature in the second cooling step is lowered to a temperature lower than −44 ° C. Is possible.

In order to solve the above problems, the refrigeration apparatus of the present invention comprises:
A freezer provided in the freezing apparatus, at least a first cooling area, a second cooling area after the first cooling area, a refrigerator disposed in each cooling area in the freezing apparatus and capable of controlling supply of cold air; A conveyor that continuously introduces and transports objects to each of the cooling areas, and the cold air temperature used in each of the areas is set to a constant temperature to cool the object to be cooled without causing an overcooling state. A freezing device that freezes ,
The refrigerator in the first cooling area supplies cold air having a first cold air temperature to the first cooling area, and the conveyor removes the object to be cooled when the temperature of the object to be cooled reaches near the freezing temperature. Continuously introducing and transferring from the cooling area to the second cooling area, and the refrigerator in the second cooling area supplies cold air having a second cold air temperature lower than the first cold air temperature to the second cooling area. It is a feature.
According to this feature, when the temperature of the object to be cooled reaches near the freezing temperature, the second cold air temperature that is lower than the first cold air temperature from the first cooling area where the object to be cooled is set to the first cold air temperature. Therefore, the object to be cooled without deformation or cracking can be efficiently manufactured in large quantities.

The refrigeration apparatus of the present invention is
The first cold air temperature is set to a range of −15 ± 5 ° C., and the second cold air temperature is set to −44 ° C. or lower .
According to this feature, the first cold air temperature set at −15 ± 5 ° C. sufficiently delays the freezing of the object to be cooled starting from the outer surface side of the object to be cooled, which may cause the ice crystal to become coarse. Since the passage time of the generation temperature range can be shortened, a series of refrigeration processes can be performed without causing a large energy loss even when cooled by the second cold air temperature lower than −44 ° C.

(A) is the schematic which shows the freezing apparatus in an Example, (b) is AA sectional drawing of (a). It is a graph which similarly shows the temperature change of the to-be-cooled object by the cold wind temperature in an Example. It is a graph which illustrates the temperature change of the to-be-cooled object by the cold wind temperature in the conventional freezing method.

  Embodiments of the refrigeration method and the refrigeration apparatus according to the present invention will be described below in detail with reference to the drawings.

  As food to be frozen in this embodiment, fresh food such as agricultural products (eg, vegetables, fruits), livestock products (eg, beef, pork, chicken), marine products (eg, seafood), or These are processed products (for example: dairy products, processed foods, processed grains, cooked products, various confections including frozen confectionery), and the like.

  As shown in FIG. 1, the coupled freezing apparatus 1 constituting the refrigeration apparatus in the present embodiment is divided into two zones in which a tunnel 3 provided with a conveyor 2 for transferring food in the direction of the arrow, and in the direction of food introduction. The 1st cooling area 4 and the 2nd cooling area 5 which convey a foodstuff from downstream to upstream downstream are arrange | positioned sequentially. In order to separately control the supply of cold air to the first cooling area 4 and the second cooling area 5, the refrigerators 6 and 7 are arranged, respectively. Further, since there is a temperature difference between the first cooling area 4 and the second cooling area 5, a partition wall is provided.

  The refrigerator 6 has a first cooling area refrigeration compressor 9 connected to an evaporator 8 and a motor, and the compressed gas discharged from the compression side is liquefied by the condenser 10 and is liquefied. The refrigerant is expanded by an expansion valve 11 whose opening degree is adjusted to a predetermined degree, and in the first cooling area 4, cold air around −15 ° C. cooled by the refrigerant is blown out. In addition, the refrigerator 7 has a second cooling area refrigeration compressor 13 connected to the evaporator 12 and the motor, and the compressed gas discharged from the compression side is liquefied in the condenser 14. The liquefied refrigerant is expanded by an expansion valve 15 whose opening is adjusted to a predetermined degree, and cold air around −45 ° C. cooled by the refrigerant is blown out in the second cooling area.

  The food placed on the conveyor enters the first cooling area 4 as the conveyor 2 moves. In the first cooling area 4, the air located above the coupled freezing device 1 is cooled by the refrigerant by the ventilation of the reflux fan 16 disposed above the conveyor 2, passes through the slit of the cool air passage 17, and is increased in speed. It is blown out toward the food on the conveyor 2 as cold air around −15 ° C.

  The food passes through the partition wall and enters the second cooling area 5 for quick freezing in the next stage. In the second cooling area 5, the air located above the coupled freezing device 1 is cooled by the refrigerant by the air flow of the reflux fan 18 disposed above the conveyor 2, passes through the slit of the cool air passage 19 and is increased in speed. It is blown out toward the food on the conveyor 2 as cold air around −45 ° C. Then, the food is discharged out of the coupled freezing device 1 by the conveyor 2.

  As described above, at least the first cooling area 4 and the second cooling area 5 are continuously provided in the coupled freezing apparatus 1, and cold air can be supplied to the cooling areas 4 and 5 in the coupled freezing apparatus 1. Since the refrigerators 6 and 7 are arranged respectively, the cooling areas 4 and 5 in the coupled freezing apparatus 1 can be individually and independently temperature controlled. Therefore, by adjusting the temperature in each of the cooling areas 4 and 5, it is possible to perform optimum temperature management in accordance with the characteristics of various objects to be cooled and the characteristics of the cooling stage.

  In the present embodiment, the coupled freezing apparatus 1 having only two areas of the first cooling area 4 and the second cooling area 5 has been described. However, a coupled freezing apparatus having three or more areas is also an object. For example, it is also possible to provide a third cooling area for controlling the cooling rate with higher accuracy, and performing optimum temperature management by adding a cooling area according to the type of food to be frozen Be free. The cooling air temperature used in at least two cooling processes is set to a constant temperature, and a cooling area is provided in which the cooling air temperature for cooling the object to be cooled in the cooling process is extremely reduced stepwise, for example, 10 ° C. or more. That's fine.

  FIG. 2 is a graph showing the temperature change of the object to be cooled depending on the cold air temperature. By adjusting the time of the first cooling step (the time until reaching the freezing temperature) with respect to the cold air temperature of −15 ° C. It does not affect the transit time of the ice crystal generation temperature range that may cause the ice crystal to become coarse. In the above-described embodiment, an example in which the first cold air temperature in the initial first cooling step is set to −15 ° C. is shown. However, the first cold air temperature is set as optimum temperature management in accordance with the characteristics of various objects to be cooled. It may be any temperature of −15 ± 5 ° C. If the first cold air temperature in the first cooling step is within a range of −15 ± 5 ° C., the ice crystal becomes coarse by adjusting the time of the first cooling step with respect to the cold air temperature selected within this range. It does not affect the transit time of the ice crystal generation temperature range that may be incurred. As described above, if the first cold air temperature in the first cooling step is within a range of −15 ± 5 ° C., freezing of the object to be cooled starting from the outer surface side of the object to be cooled is sufficiently delayed.

  That is, when the object to be cooled having a high water content is cooled, for example, as shown in FIG. 3, if the cold air temperature is a constant low temperature (−40 ° C. in this case), the object to be cooled starting from the outer surface side is frozen. Too fast, it becomes impossible to absorb the volume increase caused by the phase change of the moisture content in the vicinity of the center, and as a result, a strong stress is applied to the outer part that has already been completely frozen, causing a phenomenon such as cracking. However, as described above, according to the refrigeration method of this embodiment, the delay in freezing of the object to be cooled starting from the outer surface side of the object to be cooled contributes to securing time for the volume change in the freezing process to escape to the outside. To do. Especially for fresh scallops, which are fresh food products, the first cold air temperature in the first cooling step is set within the range of −15 ± 5 ° C., so that convex deformation and cracks occur from the inside to the outside during freezing. It has been demonstrated that the risk of producing is reduced.

  In addition, as shown in FIG. 2, in the present embodiment, cold air around −45 ° C. is blown to the food on the conveyor 2 in the second cooling step, but in the initial first cooling step, the conventional constant cold air is blown. By using a temperature higher than −35 ° C. which is the temperature band, even if the cold air temperature in the subsequent second cooling step is lowered to a temperature lower than −44 ° C. (for example, −55 ° C., etc.) In this case, a series of freezing processes can be performed without causing a large energy loss.

  That is, according to the refrigeration method of the present embodiment, the cooling process is divided into a plurality of processes, and the cooling temperature used in the initial cooling process in each cooling process is at least the cooling used in the subsequent cooling processes. It is set to a temperature higher than the temperature and used for the cooling and freezing process. Therefore, if the cooling temperature used in the initial cooling process is relatively high, it becomes possible to delay freezing of the object to be cooled starting from the outer surface side of the object to be cooled, and increase the volume near the center of the object to be cooled. Absorption, that is, volume change during the freezing process, can easily escape to the outside, and the object to be cooled can be prevented from being broken. In the subsequent cooling process, by cooling the object to be cooled at a lower cold air temperature, the freezing speed is increased to shorten the time of the maximum ice crystal formation zone (around the freezing temperature) where ice crystals are likely to be generated. The coarsening can be reliably suppressed. By applying such temperature control, it is possible to prevent deformation and cracking of the object to be cooled and to prevent destruction of tissues and cells inherent to the object to be cooled as much as possible, and loss of cooling energy in the initial stage of the cooling process. Even if the cold air temperature is lowered in the subsequent cooling process, there is no significant energy loss of the refrigerator, etc. as a total of the entire process, and efficient refrigeration processing can be performed without lowering productivity than before. It becomes possible.

  In addition, the cold air temperature used in each cooling process is set to a constant temperature, and the cold air temperature for cooling the object to be cooled in the cooling process is lowered step by step. The nature of tissues and cells is different from the original, and the appropriate cooling rate differs depending on the characteristics of the various objects to be cooled and the characteristics of the cooling stage, and the optimum temperature control for each is required. Since the temperature is set at a constant temperature, optimum temperature management is possible by adjusting the time in each process.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

DESCRIPTION OF SYMBOLS 1 Connection type freezing apparatus 2 Conveyor 3 Tunnel 4 1st cooling area 5 2nd cooling area 6, 7 Refrigerator 8,12 Evaporator 9,13 Compressor 10,14 Condenser 11,15 Expansion valve 16,18 Reflux fan 17 , 19 Cold passage

Claims (6)

In a refrigeration method for cooling and freezing an object to be cooled continuously introduced and transferred without causing a supercooled state by a plurality of cooling steps,
The cooling process includes at least an initial first cooling process and a second cooling process after the first cooling process, and the cold air temperature used in each cooling process is set to a constant temperature,
The first cooling step using the first cold air temperature continues until the temperature of the object to be continuously introduced and transferred reaches the vicinity of the freezing temperature, and uses the second cold air temperature lower than the first cold air temperature. (2) A refrigeration method which is shifted to a cooling step. Frozen The method of claim 1, the cold air temperature to cool the cooling object in the previous SL cooling step is equal to or adapted to decrease stepwise.   A first cooling area that is provided in a freezing device and that performs at least the first cooling process; a second cooling area that performs the second cooling process; and a refrigerator that is disposed in each cooling area and that can control supply of cold air. The refrigeration method according to claim 1 or 2, wherein a refrigeration apparatus comprising a conveyor that continuously introduces and transfers an object to be cooled to each of the cooling areas is used.   4. The refrigeration method according to claim 1, wherein the first cold air temperature is set to a range of −15 ± 5 ° C., and the second cold air temperature is set to −44 ° C. or lower. 5. A freezer provided in the freezing apparatus, at least a first cooling area, a second cooling area after the first cooling area, a refrigerator disposed in each cooling area in the freezing apparatus and capable of controlling supply of cold air; A conveyor that continuously introduces and transports objects to each of the cooling areas, and the cold air temperature used in each of the areas is set to a constant temperature to cool the object to be cooled without causing an overcooling state. A freezing device that freezes ,
The refrigerator in the first cooling area supplies cold air having a first cold air temperature to the first cooling area, and the conveyor removes the object to be cooled when the temperature of the object to be cooled reaches near the freezing temperature. Continuously introducing and transferring from the cooling area to the second cooling area, and the refrigerator in the second cooling area supplies cold air having a second cold air temperature lower than the first cold air temperature to the second cooling area. Refrigeration equipment characterized.   6. The refrigeration apparatus according to claim 5, wherein the first cold air temperature is set to a range of −15 ± 5 ° C., and the second cold air temperature is set to −44 ° C. or lower.

Images