JP4875693B2 - Food freezing method and freezing apparatus using the same freezing method - Google Patents

Description

  The present invention relates to a food freezing method in which cold air is blown to a food to be cooled such as fresh food, and a freezing apparatus using the freezing method. More specifically, the residual stress in the food to be cooled is reduced. The present invention relates to a refrigeration method and a refrigeration apparatus using the refrigeration method.

  Conventionally, when food that is to be cooled is frozen, depending on the form (weight, dimensions, packaging) of the food, the air (cold air) temperature, the direction of the cold air (horizontal, vertical), the form of the cold air outlet, the cold air The refrigeration apparatus was configured so as to be suitable for foods to be frozen by selecting and combining the wind speeds, and the food was frozen by the refrigeration apparatus (see, for example, Patent Document 1).

  That is, when freezing food, the temperature range in which the water in the food freezes to produce ice crystals (maximum ice crystal formation zone: temperature range from the freezing point to −5 ° C.) can be passed as soon as possible. In addition, a freezing device is configured to reduce damage to cellular tissues in foods such as seafood.

  However, the product (frozen food) often breaks due to stress generated during freezing.

Japanese Patent No. 3071098 (pages 1-5, FIGS. 1-7)

  The present invention is the same as the method for freezing food, which can significantly reduce the residual stress in the food during freezing when the food is frozen, and can provide a high-quality frozen food that is less likely to break. A refrigeration apparatus using a refrigeration method can be provided.

  In order to solve the above-described problem, the method for freezing food according to the present invention provides a predetermined time interval during freezing when the object to be cooled in the cooling chamber is frozen by the cold air blown into the cooling chamber. The object to be cooled is heated a plurality of times by a heating means, and at the time of this heating, ice crystals having a predetermined particle diameter generated in the object to be cooled are directed in the melting direction to freeze the object to be cooled.

  In addition, an electric heating device or a magnetron is used as the heating means.

  Further, the heating by the heating means heats the ice crystals having a relatively large particle size in the ice crystals generated in the object to be cooled so as to be directed in the melting direction.

  A refrigeration apparatus using the refrigeration method according to the present invention is a continuous refrigeration apparatus that freezes an object to be cooled that is moving in a cooling chamber by a belt conveyor with cold air blown into the cooling chamber, The object to be cooled is heated a plurality of times with a predetermined time interval by a heating means, and during this heating, ice crystals having a predetermined particle size generated in the object to be cooled are directed in the melting direction. It is assumed that the object to be cooled can be frozen.

  In addition, a batch-type refrigeration apparatus that freezes an object to be cooled that has been conveyed into a cooling chamber by a conveying means such as a carriage with cold air blown into the cooling chamber, and the object to be cooled that is placed in the cooling chamber is heated by a heating means. Heated a plurality of times at predetermined time intervals, and at the time of this heating, it is configured to be able to freeze the object to be cooled by directing ice crystals of a predetermined particle size generated in the object to be cooled in the melting direction is there.

  Further, the heating means is configured by using an electric heating device or a magnetron.

  Further, the heating by the heating means heats the ice crystals having a relatively large particle size in the ice crystals generated in the object to be cooled so as to be directed in the melting direction.

  According to the method for freezing food according to the present invention, when the object to be cooled containing water such as food is frozen, the object to be cooled is heated by the heating means a plurality of times at predetermined time intervals during the freezing. During this heating, the ice crystals generated in the object to be cooled are oriented in the melting direction to freeze the object to be cooled, so that the residual stress in the food that is generated during freezing of the food that is the object to be cooled is reduced. Therefore, it is difficult for the product to break, and a high-quality frozen food can be provided.

  In other words, the object to be cooled that has been frozen is heated by the heating means, and the heating is performed a plurality of times during the process of freezing. The internal stress that occurs inside is directed to the melting direction of the ice crystals that are generated by heating and with each heating, so the residual stress in the food during freezing is dramatically reduced. can do.

  Also, if an electric heating device is used as the heating means, during heating, a larger amount of current flows through the ice crystal having a larger particle size than that of the ice crystal having a smaller particle size, and the ice crystal having a larger particle size is generated by the heat generated by this current. Since it melts or hinders its growth, the particle size of frozen ice crystals can be made uniform to further improve the quality of the product (frozen food).

  Hereinafter, a food freezing method and a freezing apparatus using the freezing method according to the present invention will be described with reference to the accompanying drawings.

  In the method for freezing food according to the present invention, when the object to be cooled in the cooling chamber is frozen by the cool air blown into the cooling chamber, the object to be cooled is heated by a heating means at a predetermined time interval during the freezing process. The object to be cooled is frozen by heating a plurality of times and directing ice crystals having a predetermined particle diameter generated in the object to be cooled in the melting direction, and the freezing method will be described with reference to FIG.

FIG. 1 is a cross-sectional view of a food showing the state of moisture in it, and the process until the moisture in the food becomes ice crystals is indicated by arrows in FIG.
Further, the heating means shown in FIG. 1 is described by taking an energization heating device as an example.

  First, when the food that is the object to be cooled in the cooling chamber starts to be cooled by the cold air blown into the cooling chamber, the water in the food starts to be cooled by the cold air (the upper left figure in FIG. 1), and the outside of the food Freezing starts from the moisture of the water, and stress is generated inside the food due to this freezing (the upper middle diagram in FIG. 1).

  Next, when heated by an electric heating device as a heating means, a current flows through the water in the middle of the ice crystallization (the upper right diagram in FIG. 1), and the ice that has progressed into the water by the heat generated by the current flow. Crystallization is relaxed, and at the same time, the stress generated in the moisture is reduced or removed.

  Next, when the air is cooled again by the cool air blown into the cooling chamber, the water in the middle of ice crystallization begins to freeze again (the middle right diagram in FIG. 1), and stress is also generated inside the food.

  Next, when heated again by an electric heating device, a current flows in the water during the ice crystallization (middle stage middle diagram in FIG. 1), and the ice crystallization progressing in the water due to heat generated by the current flow. At the same time, the stress generated inside the food is reduced or removed.

  Next, when the air is cooled again by the cool air blown into the cooling chamber, the water in the middle of ice crystallization begins to freeze again (the middle left figure in FIG. 1), and stress is also generated inside the food.

  Next, when heated again with an electric heating device, a current flows in the water during the ice crystallization (lower left figure in FIG. 1), and the ice crystallization progressing in the water due to the heat generated by the current flow At the same time, the stress generated inside the food is reduced or removed.

  Next, when it is cooled again by the cool air blown into the cooling chamber, the water during the ice crystallization is completely frozen by the cooling (the lower right diagram in FIG. 1), and the freezing of the food as the object to be cooled is completed. .

  In FIG. 1, the number of times of heating is three, but the number of times of heating, the heating temperature, and the like are determined by the form (weight, dimensions, packaging) of the food to be cooled and the heating means used.

  In addition, the current flowing through the water during crystallization of ice due to heating is such that the water in the food, which is the object to be cooled, is cooled by cold air, and the ice particles having a small particle size among the many ice crystal grains generated in the food. Since the ice crystals having a larger particle size than the crystals flow to the ice crystals having a larger particle size, the ice crystals having a larger particle size through which this current flows are melted into the ice crystals having a smaller particle size due to the heat generated by the current. It is possible to make the particle diameters of ice crystals generated in foods uniform.

  Further, a freezing apparatus using the method for freezing food according to the present invention will be described. The freezing apparatus (continuous freezing apparatus) has a positive pressure above the inside of the freezing apparatus 1 as in the example shown in FIG. A chamber 6 is provided, and a cooler 7 provided with a fan 7a for blowing is disposed on the left and right sides of the positive pressure chamber 6, respectively.

  Although not shown in the figure, an air intake port following the cooler 7 is provided outside the partition wall constituting the positive pressure chamber 6.

  In the lower slit 6 a constituting the positive pressure chamber 6, a large number of injection ports 6 b facing the upper belt surface of the belt conveyor 4 described later are arranged.

  A cooling chamber 2 is provided below the slit 6 a in the positive pressure chamber 6, and a belt conveyor 4 serving as a conveying means for placing the object 5 to be cooled and moving horizontally is disposed in the cooling chamber 2. For example, 4 may be formed of a steel belt having excellent heat conductivity.

  In the cooling chamber 2, three heating devices 3 for heating the objects 5 to be cooled on the belt conveyor 4 are provided.

  In the refrigeration apparatus 1 shown in FIG. 2, three heating devices 3 are provided. However, three or more heating devices 3 are used depending on the form (weight, dimensions, packaging) of the food to be cooled and the heating means used. Or it may be less than this.

  The heating device 3 is preferably composed of an energization heating device capable of directly applying heat to the object to be cooled. Similarly, 3 MHz to 3,000 MHz (preferably 915 MHz) capable of directly applying heat to the object to be cooled. To 2,450 MHz) in some cases.

  In addition, a heater such as a general electric heater may be used as long as heat can be indirectly irradiated to a level at which the influence on the freezing process can be ignored.

  Then, the refrigeration apparatus 1 causes the air cooled by the cooler 7 disposed in the positive pressure chamber 6, that is, cold air, to be blown into the positive pressure chamber 6 by the fan 7 a, and this cold air 8 is supplied to the positive pressure chamber 6. 6 is blown toward the object 5 to be cooled on the belt conveyor 4 that moves horizontally in the cooling chamber 2 from a large number of injection ports 6b provided in the lower slit 6a. The object to be cooled 5 on the belt conveyor 4 moving by the belt conveyor 4 is heated by the heating device 3 during the freezing process in the cooling chamber 2.

Therefore, the object to be cooled 5 on the belt conveyor 4 that enters the cooling chamber 2 from the inlet 1 a of the refrigeration apparatus 1 by the belt conveyor 4 and moves in the cooling chamber 2 toward the outlet 1 b is transferred to the belt conveyor 4. When freezing progresses by the cold air 8 blown from above and moves below the heating device 3 by the movement of the belt conveyor 4, it is heated by the heating device 3. When configured, current flows through the water in the middle of ice crystallization in the food to be cooled 5, and the ice crystallization proceeding in the water is loosened due to the heat generated by the current, and at the same time, it is generated in the water. Stress is also reduced or removed.
Therefore, the continuous refrigeration apparatus as the refrigeration apparatus 1 freezes the food as the object to be cooled 5 while relaxing or removing the stress generated in the object to be cooled 5 during the freezing process by heating with the heating apparatus 3.

  In the embodiment, reference numeral 1c in FIG. 2 is a front chamber provided before and after the cooling chamber 2, reference numeral 4a is a driving roller of the belt conveyor 4, and reference numeral 4b is a driven roller of the belt conveyor 4.

  Further, another refrigeration apparatus using the food refrigeration method according to the present invention will be described. The refrigeration apparatus (batch-type refrigeration apparatus) is cooled in a freezer 1 ′ as a refrigeration apparatus, as shown in FIG. A cooler 7 provided with a fan 7 a for blowing air is disposed above the chamber 2.

  In the cooling chamber 2, four heating devices 3 for heating the object 5 to be cooled in the cooling chamber 2 are provided.

  The freezer 1 ′ shown in FIG. 3 has four heating devices 3 in the cooling chamber 2, but it is heated depending on the form (weight, dimensions, packaging) of the food to be cooled and the heating means used. There may be four or more devices 3 or less.

  The heating device 3 is preferably composed of a magnetron capable of irradiating microwaves of 3 MHz to 3,000 MHz (preferably 915 MHz to 2,450 MHz) that can directly apply heat to the object to be cooled from a remote place, If the heat can be indirectly irradiated to such a level that the influence on the freezing process can be ignored, it may be configured using an ordinary electric heater.

  Further, there may be a case in which an electrification heating device is used which is set with electrodes (not shown) on the object 5 to be cooled.

  And this freezer 1 'cools the air in the cooling chamber 2 with the cooler 7 distribute | arranged in the cooling chamber 2, and injects the cooled air, ie, cool air 8, into the cooling chamber 2 with the fan 7a. The cool air 8 is blown onto the object 5 to be cooled on the carriage 9 carried from the outside, and the heating device 3 provided in the cooling chamber 2 is operated a plurality of times at predetermined time intervals. Thus, the object 5 to be cooled on the carriage 9 is heated a plurality of times during the freezing process in the cooling chamber 2.

Accordingly, the object to be cooled 5 on the carriage 9 in the cooling chamber 2 is frozen by the cool air 8 blown from above and is heated by the heating device 3 a plurality of times at predetermined time intervals. For example, when the heating device 3 is composed of a magnetron, water in the middle of ice crystallization in the food that is the object to be cooled 5 vibrates due to microwaves, and the ice crystallization that has progressed into the water due to heat generated by the vibration is generated. At the same time, the stress in the moisture is reduced or removed.
Therefore, the batch-type freezing apparatus serving as the freezer 1 ′ freezes the food serving as the object to be cooled 5 while relaxing or removing the stress generated in the object to be cooled 5 during the freezing process by heating with the heating device 3.

The figure which showed the process in which the water | moisture content in the foodstuff becomes an ice crystal in the freezing method of the foodstuff which concerns on this invention. The schematic structure figure inside the device showing an example of the continuous refrigerating device which uses the freezing method concerning the present invention. The schematic structure figure inside the device showing an example of the batch type refrigeration device which uses the freezing method concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus 1 'Freezer 1a Inlet 1b Outlet 1c Front chamber 2 Cooling chamber 3 Heating device 4 Belt conveyor 4a Drive roller 4b Driven roller 5 Cooled object 6 Positive pressure chamber 6a Slit 6b Injector 7 Cooler 7a Fan 8 Cool air 9 Trolley

Claims (7)

When the object to be cooled in the cooling chamber is frozen by the cool air blown into the cooling chamber, the object to be cooled is heated a plurality of times by a current heating device or a magnetron at predetermined time intervals during the progress of freezing. A method of freezing food, wherein ice crystals having a predetermined particle diameter generated in the object to be cooled are directed in the melting direction during heating. 2. The heating according to claim 1, wherein heating by the electric heating device or the magnetron is performed so that ice crystals having a relatively large particle diameter are oriented in a melting direction among ice crystals generated in an object to be cooled. How to freeze food. When heat is applied multiple times by the current heating device or magnetron, the internal stress that occurs in the ice crystal when the water in the food, which is the object to be cooled, crystallizes into ice. The method for freezing food according to claim 1 or 2, wherein the crystals are oriented in the melting direction to reduce residual stress in the food during freezing of the food. A continuous refrigeration apparatus that freezes an object to be cooled that is moving in a cooling chamber by a belt conveyor by the cool air blown into the cooling chamber, and the object to be cooled that is moving in the cooling chamber is an electric heating device or a magnetron. Heating is performed a plurality of times with a predetermined time interval, and at this time, the ice crystal having a predetermined particle diameter generated in the object to be cooled is directed in the melting direction so that the object to be cooled can be frozen. Refrigeration equipment. A batch-type refrigeration apparatus that freezes an object to be cooled that has been conveyed into a cooling chamber by a conveying means such as a carriage with the cool air blown into the cooling chamber, and the object to be cooled placed in the cooling chamber is heated by an electric heating device or a magnetron Heating is performed a plurality of times with a predetermined time interval, and at this time, the ice crystal having a predetermined particle diameter generated in the object to be cooled is directed in the melting direction so that the object to be cooled can be frozen. Refrigeration equipment. The resistance heating apparatus or heating by magnetron, claim 4 or formed by heating to direct to the melting direction relatively large grain size of the ice crystals in the ice crystals occurring in the object to be cooled 5. The refrigeration apparatus according to 5 . When heat is applied multiple times by the current heating device or magnetron, the internal stress that occurs in the ice crystal when the water in the food, which is the object to be cooled, crystallizes into ice. The refrigeration apparatus according to any one of claims 4 to 6, wherein the crystals are oriented in the melting direction to reduce residual stress in the food that is generated during freezing of the food.

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