JP4152695B2 - Method for producing fresh frozen raw vegetables - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for freezing fresh vegetables, and more particularly, to a method for producing fresh fresh frozen vegetables that can suppress the destruction of tissue cell bodies of fresh vegetables and maintain the freshness of fresh vegetables.
[0002]
[Prior art]
Conventionally, there is frozen storage as a method for maintaining and maintaining the freshness of foods, foods, living bodies and the like for a long period of time. However, conventional frozen storage methods cannot completely prevent deterioration in quality and deterioration in freshness, such as changes in the color of the object to be frozen, deterioration in taste, and the occurrence of drip. It was. To-be-frozen items such as foodstuffs, foods and living organisms are bound water bound to molecules such as proteins constituting them, and free water that can freely move within the to-be-frozen object without being bound by these molecules. Contains a large amount of water. When frozen, this free water freezes and grows as ice crystals. If the ice crystals become coarse, the cells of the object to be frozen are destroyed, and in foods, foods, etc., drip is generated when thawing, making it difficult to restore the original state of the living body, reducing the quality and freshness. It was a problem.
[0003]
Ice crystal coarsening occurs when the time for passing through the ice crystal formation temperature range is slow during freezing. Therefore, the object to be frozen is immersed in the liquid refrigerant, or sprayed with the liquid refrigerant on the object to be frozen, and rapidly cooled so as to pass through the ice crystal generation temperature range quickly, and the ice crystals are prevented from coarsening and frozen. A way to do this is considered.
[0004]
[Problems to be solved by the invention]
Conventionally, using this rapid cooling / freezing, vegetables have been frozen to be frozen vegetables. However, in the method of immersing the object to be frozen in the liquid refrigerant, the surface layer can be rapidly cooled, but a frozen layer is formed on the surface layer. Cooling of the object to be frozen is controlled by heat transfer from the surface, but due to the presence of the surface frozen layer, heat transfer to the inside is hindered and internal cooling is delayed. There is a problem that the coarsening of the crystal occurs, and the coarsening of the ice crystal cannot be prevented. For this reason, in this frozen vegetable manufacturing method using rapid cooling / freezing, the cell organization of raw vegetables is destroyed, and it is good to make powdery vegetables, but the fresh taste and original state of raw vegetables are maintained. There was a problem that could not be done.
[0005]
This invention is made | formed in view of the problem of the above prior arts, and it aims at providing the manufacturing method of the high freshness frozen raw vegetable which can maintain the fresh taste of a raw vegetable at least.
[0006]
[Means for Solving the Problems]
In order to achieve the above-described problems, the present inventor diligently studied the factors affecting the coarsening of ice crystals. As a result, by rapidly cooling and freezing under the action of fluctuating magnetic field and static magnetic field or even alternating electric field, the cell tissue of the object to be frozen is not destroyed, and even if the object to be frozen is fresh vegetables, freshness and quality It was found that it is possible to maintain. And in fresh vegetables, in order to maintain the fresh taste of raw vegetables, it was found that the fluctuating magnetic field and the static magnetic field or even the uniformity of the alternating electric field is important.
[0007]
The present invention has been completed based on the above findings and further studies.
That is, the gist of the present invention is as follows.
(1) After storing raw vegetables or boiled raw vegetables in an internal closed space of a freezer having a static magnetic field generating means and a variable magnetic field generating means and rapidly cooling to a predetermined temperature under the action of the static magnetic field and the variable magnetic field, In the method for producing frozen raw vegetables that is quickly frozen at the predetermined temperature, the static magnetic field generating means is a static magnetic field generating means for generating a static magnetic field of 1 to 10000 Gaus, and the variable magnetic field generating means is energized with alternating current. A plurality of electromagnetic coil structures that generate a varying magnetic field of 0.1 to 1000 Gaus, and the electromagnetic coil structure spans a holder that holds the raw vegetables, or a holder that holds the raw vegetables A method for producing high freshness frozen raw vegetables, characterized in that it is a variable magnetic field generating means arranged so as to surround and a plurality of the electromagnetic coil structures arranged in parallel, perpendicularly or crossing along the holder.
(2) In (1), the fluctuating magnetic field generating means arranges a pair of electromagnetic coil structures that generate a fluctuating magnetic field by energizing an alternating current so as to sandwich a net conveyor belt that holds the raw vegetables, and A method for producing high freshness frozen raw vegetables, characterized in that a plurality of pairs are arranged in parallel along the traveling direction of the net conveyor belt.
(3) In (1) or (2), the electromagnetic coil structure is formed by winding a coil-forming base material having a predetermined shape and a highly conductive wire with an insulating coating around the base material. A method for producing a fresh and fresh frozen vegetable, characterized in that the electromagnetic coil structure is formed by sealing the electromagnetic coil with a caulking material.
(4) In any one of (1) to (3), in addition to the static magnetic field and the variable magnetic field, an alternating electric field having a variable frequency of 50 Hz to 5 MHz is further applied. A method for producing vegetables.
(5) In any one of (1) to (4), the raw vegetables are boiled with frozen raw vegetables frozen after being rapidly cooled under the action of a static magnetic field and a variable magnetic field, or an alternating electric field. A method for producing a fresh fresh frozen vegetable characterized by the above.
(6) In any one of (1) to (5), an ion wind is superimposed on the cold air in the freezer.
(7) A high freshness frozen raw vegetable prepared by the method for producing a high freshness frozen raw vegetable according to any one of (1) to (6).
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, raw vegetables or boiled raw vegetables are stored in a closed space of a freezer having a static magnetic field and a variable magnetic field generating means to suppress freezing of moisture under the action of the static magnetic field and the variable magnetic field. However, after rapidly cooling to a predetermined temperature, the application of the magnetic field is stopped, and freezing is instantaneously performed at the predetermined temperature. The predetermined temperature is preferably -20 to -50 ° C. In the present invention, an alternating electric field may be applied in addition to the static magnetic field and the variable magnetic field.
[0009]
By rapidly cooling to a predetermined temperature under the action of a variable magnetic field, a static magnetic field, or even an alternating electric field, freezing of moisture is suppressed, and destruction of the cellular tissue of raw vegetables that are to be frozen is suppressed, and raw vegetables The fresh taste and the original state can be maintained.
In the present invention, in order to apply a strong and uniform variable magnetic field to raw vegetables that are to be frozen in particular, the variable magnetic field generating means disposed in the freezer spans a holder that holds the object to be frozen (raw vegetables). Or surrounding the holder for holding the object to be frozen (raw vegetables), or sandwiching the holder for holding the object to be frozen (raw vegetables), It arrange | positions so that it may be parallel, orthogonal, or cross | intersect with frozen thing (raw vegetable), and a fluctuation magnetic field is made to act (apply) to the raw vegetable which is to-be-frozen.
[0010]
In the present invention, the varying magnetic field generating means is the electromagnetic coil structure 1 that generates a varying magnetic field by energizing an alternating current.
The electromagnetic coil structure 1 includes a coil-forming base material 11 having a predetermined shape and an electromagnetic coil 12 formed by winding a high-conductivity wire 121 with an insulating coating around the base material 11 a predetermined number of times. The electromagnetic coil 12 is sealed with a caulking material 13. In addition, it is preferable that this base material is made into a cross-sectional case shape so that the above-mentioned electromagnetic coil can be stored. The electromagnetic coil sealed with the caulking material 13 is housed in a base material with a case-shaped cross section, and a lid made of the same material is attached to the base material in the case shape with an adhesive or the like. The electromagnetic coil structure 1 in which 12 is hermetically stored is obtained.
[0011]
The substrate 11 is preferably a material having electrical insulation, water resistance, heat resistance, and magnetic permeability. As such a material, plastic, rubber, wood or a composite material thereof is preferable.
Note that the shape of the base material 11 having a cross-sectional case shape is preferably not particularly limited, and is preferably a predetermined shape corresponding to a holding tool for mounting or holding an object. If the holder is a rack-type holder, a rectangular or square ring shape is preferred, and if it is a net belt conveyor type holder, a rectangular or square ring shape is preferred.
[0012]
Moreover, as a highly conductive wire to be used, a single wire or a stranded Cu wire is exemplified. Note that a highly conductive wire wound around a substrate to form an electromagnetic coil is coated (coated) with a highly electrically insulating insulating coating. Examples of the high electrical insulating insulating film include polyimide resin, nylon, polytetrafluoroethylene (trade name: Teflon), and the like.
[0013]
FIG. 3 schematically shows an example of the electromagnetic coil structure 1 in which the base material has a rectangular ring shape.
By arranging a plurality of electromagnetic coil structures 1 having such a structure and generating a variable magnetic field by energizing an alternating current, a variable magnetic field with a uniform strength can be obtained and uniformly applied to the object to be frozen (raw vegetables). A varying magnetic field of strength can be applied. Needless to say, the electromagnetic coil structure used in the present invention is not limited to this. In addition, it is preferable to appropriately determine the number and interval of the electromagnetic coil structures 1 according to the length of the holder, the degree of uniformity of the magnetic field strength, and the like.
[0014]
By flowing an alternating current having a constant frequency through the electromagnetic coil 12 of the electromagnetic coil structure 1, a variable magnetic field in which the direction of the magnetic field periodically varies can be formed. The alternating current flowing through the electromagnetic coil 12 is preferably an alternating current having a frequency of 50 Hz to 5 MHz, and the strength of the variable magnetic field has an appropriate value depending on the type of raw vegetables, and is preferably 0.1 to 1000 Gaus. If the strength of the fluctuating magnetic field is less than 0.1 Gaus, it is difficult to determine the effect of magnetism, while if it exceeds 1000 Gaus, there is a problem that an unnecessarily large magnetic field is applied.
[0015]
An example of a freezer having a fluctuating magnetic field generating means suitable for the present invention is shown in FIG.
When the freezer is a rack-type batch type freezer, as shown in FIG. 1, the electromagnetic coil structure 1 is placed on a rack-type holder (rack-type tray) 4 that holds an object to be frozen (raw vegetables) 2. A plurality of rack-shaped holders (rack-type trays) 4 that hold the object to be frozen (raw vegetables) are provided so as to extend over and the electromagnetic coil structures 1 are parallel to the rack-type holder. It is preferable to arrange them in parallel. In addition, it may replace with parallel and may be arranged in parallel so that it may be orthogonal or crossed.
[0016]
By arranging the electromagnetic coil structure in this way, a fluctuating magnetic field having a uniform strength in the horizontal direction is applied to the object to be frozen.
In addition, when the freezer is a tunnel type or spiral type, and the object to be frozen is continuously stored and frozen in the closed space inside the freezer by the net conveyor belt, the rectangular ring-shaped electromagnetic coil structure is A pair of holders (net conveyor belts) for holding frozen products are placed on the upper and lower sides, ie, a pair, and a plurality of pairs are arranged in parallel in the traveling direction of the net conveyor belt ( It is preferable to arrange them side by side.
[0017]
Moreover, in this invention, in addition to a fluctuation | variation magnetic field, a static magnetic field is made to act on the raw vegetable which is to-be-frozen. The static magnetic field generating means 7 for applying a static magnetic field is preferably a permanent magnet. The permanent magnet is preferably provided with the same polarity on the side wall of the freezer 31 so that a static magnetic field acts on the object to be frozen (raw vegetables) 2 placed in the internal space of the freezer 31. In addition, the permanent magnet as the static magnetic field generating means 7 has the same polarity so that the static magnetic field acts on the object to be frozen (raw vegetables) 2 and the back side of the holding means 41 for holding the objects to be frozen 2 (raw vegetables). May be provided.
[0018]
The strength of the static magnetic field acting on the object to be frozen (raw vegetables) is preferably 1 to 10000 Gaus. If the strength of the static magnetic field is less than 1 Gaus, it is difficult to distinguish the effect of the static magnetic field due to the influence of geomagnetism. On the other hand, considering the production limit of the permanent magnet, the upper limit of the static magnetic field is preferably 10000 Gaus. 1 and 2 show a state in which the static magnetic field generating means 7 is provided with the same polarity on the side wall of the freezer 31 so that the static magnetic field acts in the vertical direction. Needless to say, it may be in the horizontal direction.
[0019]
In the freezer suitable for the present invention, in addition to the variable magnetic field generating means 1 and the static magnetic field generating means 7, as shown in FIG. 1, the object to be frozen (raw vegetables) 2 housed in the internal space of the freezer is cooled. Needless to say, it has a refrigeration means 5 for generating cold air and a blower means 55 provided inside the freezer for supplying the cold air to the object to be frozen (raw vegetables). Although not particularly illustrated, it goes without saying that a heat insulating member is disposed between the outer wall and the inner wall of the freezer 31.
[0020]
As the refrigeration means 5, any of the generally known refrigeration cycles in which the compressor 53, the condenser 54, the expansion valve 52, and the cooling pipe (evaporator) 51 are connected and the refrigerant circulates can be applied. The expansion valve 52 and the cooling pipe (evaporator) 51 are installed in the internal space of the freezer 31 and contribute to the generation of cold air. Moreover, in order to promote the rapid temperature fall of a to-be-frozen thing (raw vegetables), it is preferable to comprise the inner wall surface of a freezer with the member which has a far-infrared radiation absorption ability. The inner wall surface may be coated with a material having far-infrared radiation absorption ability, and a plate-like member having far-infrared radiation absorption ability may be disposed on the inner wall surface. Thereby, the radiant heat (far infrared rays) radiated | emitted from a to-be-frozen thing (raw vegetables) can be absorbed rapidly, and it helps to achieve the temperature fall of a to-be-frozen object rapidly. The member having the far-infrared radiation absorbing ability disposed on the inner wall surface absorbs the heat of the object to be frozen in proportion to the fourth power of the temperature difference ΔT between the temperature of the object to be frozen and the inner wall surface. Can greatly contribute to rapid cooling.
[0021]
In addition, as shown in FIG. 2, an ionic wind composed of negative air ions generated by the ionic wind generator 6 may be superimposed on the cold air 57 blown by the blower fan 55 which is the blower unit. . Supplying cold air with superposed ionic wind to the object to be frozen (raw vegetables) promotes direct heat transfer to the object to be frozen (raw vegetables), promotes heat removal from the object to be frozen, A rapid temperature drop is promoted, and the freshness of the raw vegetables is further promoted. The ion wind generator preferably includes a tubular positive electrode, a linear negative electrode inserted in the tubular positive electrode, and a voltage generator that applies a voltage between the positive electrode and the negative electrode. Further, as shown in FIG. 2, it is preferable to dispose a honeycomb structure 56 made of a high thermal conductivity material in the passage of cool air in the freezer. By allowing the cool air to flow through the honeycomb structure 56, it is possible to promote a temperature drop and uniform rectification of the cold air. The honeycomb structure 56 may be any structure as long as it allows air to pass through cool air and cold air, and the structure is not particularly limited. Further, the installation location of the honeycomb structure is not particularly limited as long as it is a passage of cool air and cold air.
[0022]
Although not particularly shown in FIGS. 1 and 2, in the present invention, an alternating electric field may be further applied to the raw vegetables that are to be frozen, in addition to the above-described fluctuating magnetic field and static magnetic field. . By applying an alternating electric field to a raw vegetable that is to be frozen in addition to a variable magnetic field and a static magnetic field, it becomes easier to maintain the raw vegetable with high freshness and high quality.
[0023]
The alternating electric field generating means for applying the alternating electric field applies at least one pair of electrodes arranged opposite to each other so as to sandwich the raw vegetable as the object to be frozen, and applies the alternating electric field between the pair of electrodes. It is preferable to have an alternating electric field generator that performs an alternating electric field on a material to be frozen (raw vegetables) through a pair of electrodes. The alternating electric field generator has a frequency generator, preferably a variable frequency, has an amplifier circuit, and applies a desired electric field strength (10 V / cm to 70 V / cm 2) to at least a pair of electrodes. It is preferable to do. As the alternating electric field to be applied, it is effective to continuously scan the electric field energy having a frequency of 50 Hz to 5 MHz, or to make the electric field energy by changing the frequency stepwise (stepped). By causing an alternating electric field and a magnetic field to act on the object to be frozen at the same time, free water contained in the object to be frozen moves to combined water, which reduces the free water and reduces the probability of ice crystal formation. Further, nucleation of ice crystals and coarsening thereof can be further suppressed. Thereby, since cool air can be more effectively transmitted to the inside of the object to be frozen, the cooling rate of the object to be frozen can be remarkably increased.
[0024]
As described above, by rapidly cooling and freezing raw vegetables under the action of a static magnetic field and a variable magnetic field, or even an alternating electric field, nucleation of ice crystals and their coarsening are suppressed, The destruction of the cell tissue is prevented, and the raw state can be maintained even when frozen. The product frozen in this way does not cause drip when thawing, and can ensure the fresh taste of raw vegetables.
[0025]
It is preferable that raw vegetables are boiled with warm water of about 60 ° C. before freezing and then frozen at least under the action of a static magnetic field and a uniform magnetic field as described above. Alternatively, raw vegetables frozen as raw under the action of at least a static magnetic field and a uniform fluctuation magnetic field may be boiled with hot water of about 60 ° C. and frozen again under the action of at least a static magnetic field and a uniform fluctuation magnetic field. By freezing the frozen raw vegetables with hot water of about 60 ° C., it is possible to ensure fresh vegetables with high freshness and quality.
[0026]
【Example】
Example 1
As shown in FIG. 1, four electromagnetic coil structures 1 are arranged in parallel with the longitudinal direction of a holder (rack-type tray) 4 as a variable magnetic field generating means, and permanent magnets 7 are installed in a freezer as a static magnetic field generating means. In the internal space of the freezer 31 on the side, hold raw vegetables (spinach and chilli bean) in a holder (rack-type tray) 4 under the action of a static magnetic field and a variable magnetic field. It was rapidly cooled to 30 ° C. to obtain a frozen raw vegetable. In addition, as a result of adjusting so that the magnetic field which consists of a static magnetic field and a fluctuation | variation magnetic field might act on a to-be-frozen object, the magnetic field strength on a holder was almost uniform at 5-10Gaus. In addition, the case where it cooled rapidly to -30 degreeC without the effect | action (application) of a magnetic field, and was set as the frozen raw vegetable was made into the comparative example.
[0027]
The obtained frozen raw vegetables were naturally thawed, then boiled in warm water at 60 ° C., and the taste was examined. As a result, in the example of the present invention that was rapidly cooled and frozen under the action of a magnetic field, no drip was produced by thawing, and the raw taste was reproduced. On the other hand, in the comparative example, the frozen vegetable cells were destroyed by thawing, and the original state could not be maintained, causing dripping, drip, and lacking in taste.
[0028]
(Example 2)
Frozen spinach and frozen lentil as a frozen raw vegetable in the same manner as in Example 1 were boiled with warm water at 60 ° C, and then rapidly cooled to -30 ° C under the same conditions as in Example 1. The frozen vegetables were frozen at that temperature to obtain frozen raw vegetables (frozen spinach, frozen green beans). The obtained frozen raw vegetables were naturally thawed and then eaten, and the taste was examined. As a result, it was found that, in the same manner as in Example 1, in the present invention example that was rapidly cooled and frozen under the action of a magnetic field, drip was not generated by thawing, and deliciousness could be ensured.
[0029]
Example 3
Raw vegetables (1 spinach and 1 piece each) are drained with 60 ° C hot water for 30 seconds, drained, and -30 ° C under the same magnetic field conditions as in Example 1 in the freezer shown in FIG. It was rapidly cooled to a temperature and frozen at that temperature to obtain a frozen raw vegetable. Moreover, the case where it cooled rapidly and frozen without applying a magnetic field similarly to Example 1 was made into the comparative example. The obtained frozen raw vegetables were naturally thawed and then eaten, and the taste was examined. As a result, all of the frozen raw vegetables of the present invention that were rapidly cooled and frozen under the action of a magnetic field did not produce drip by thawing, and the original raw taste could be reproduced. On the other hand, in the comparative example, drip was generated by thawing, and the taste was lacking.
[0030]
Example 4
As in the first embodiment, four electromagnetic coil structures 1 are arranged in parallel with the longitudinal direction of the holder (rack type tray) 4 as the variable magnetic field generating means, and the permanent magnet 7 is used as the static magnetic field generating means of the freezer. In the internal space of the freezer 31 on the side surface, a negative ion generator 6 is further disposed in the passage of the cold air 57 as shown in FIG. 2 to hold a raw vegetable (one spinach bundle) as an object to be frozen ( Rack type tray) 4 and rapidly cooled to −30 ° C. under the action of a static magnetic field and a variable magnetic field to obtain frozen raw vegetables. In addition, the magnitude | size of the static magnetic field and fluctuation | variation magnetic field which act on a to-be-frozen object was made the same as that of Example 1. Further, the negative ion generator 6 has a shape in which a stainless steel cylinder having a diameter of 20 mm and a length of 50 mm is used as a positive electrode, and a needle electrode as a negative electrode is inserted 15 mm into the center of the cylindrical space. An AC electrostatic potential of 7000 V was applied to these electrodes to generate an ion wind, which was superimposed on the cold air 57.
[0031]
The obtained frozen spinach was higher in freshness and brighter than when the ionic wind was not superimposed. It is considered that by superimposing the ion wind on the cold air, the heat transfer is promoted and the oxidation is suppressed, and the high freshness maintenance is further promoted.
[0032]
【The invention's effect】
As described above in detail, according to the present invention, frozen raw vegetables that maintain high freshness and can reproduce raw deliciousness equivalent to raw vegetables can be easily and stably produced. There is a remarkable effect.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view schematically showing an example of a freezer suitable for the present invention.
FIG. 2 is a schematic explanatory view schematically showing an example of a freezer suitable for the present invention.
FIG. 3 is a schematic explanatory view schematically showing an example of an electromagnetic coil structure which is a fluctuating magnetic field generating means suitable for the present invention.
[Explanation of symbols]
1 Electromagnetic coil structure
11 Substrate
12 Electromagnetic coil
121 Highly conductive wire with insulation coating
13 Caulking material
1a AC supply means 2 Object to be frozen (raw vegetables)
31 Freezer 4 Holder (Rack type holder, Rack type tray)
5 Freezing means (refrigerant)
6 Ion wind generator 7 Static magnetic field generating means (permanent magnet)
56 Honeycomb structure
51 Cooler
52 Expansion valve
53 Condenser
54 Refrigerator
55 Blower (cold) fan
57 Cold air

Claims (7)

Raw vegetables or boiled raw vegetables are stored in an internal closed space of a freezer having a static magnetic field generating means and a variable magnetic field generating means, rapidly cooled to a predetermined temperature under the action of a static magnetic field and a variable magnetic field, In the method for producing a frozen raw vegetable that is quickly frozen at a temperature, the static magnetic field generating means is a static magnetic field generating means that generates a static magnetic field of 1 to 10000 Gaus, A plurality of electromagnetic coil structures that generate a 1000 Gaus variable magnetic field, and the electromagnetic coil structure spans a holder that holds the raw vegetables or surrounds the holder that holds the raw vegetables And a method for producing a fresh frozen raw vegetable, wherein the plurality of electromagnetic coil structures are variable magnetic field generating means arranged so as to be parallel, orthogonal, or crossed along the holder. The fluctuating magnetic field generating means is provided with a pair of electromagnetic coil structures that generate a fluctuating magnetic field by energizing alternating current so as to sandwich the net conveyor belt holding the raw vegetables, and along the traveling direction of the net conveyor belt The method for producing fresh vegetables with high freshness according to claim 1, characterized in that a plurality of pairs are arranged in parallel to generate a varying magnetic field generating means. The electromagnetic coil structure has a coil-forming base material having a predetermined shape, and an electromagnetic coil formed by winding a high-conductivity wire with an insulating coating around the base material, and the electromagnetic coil is made of a caulking material. It is an electromagnetic coil structure formed by sealing, The manufacturing method of the high freshness frozen raw vegetables of Claim 1 or 2 characterized by the above-mentioned. 4. The method for producing fresh fresh frozen vegetables according to claim 1, wherein an alternating electric field having a frequency of 50 Hz to 5 MHz is applied in addition to the static magnetic field and the variable magnetic field. 5. The fresh vegetable according to claim 1, wherein the fresh vegetable is boiled with a frozen fresh vegetable that has been rapidly cooled and frozen under the action of a static magnetic field and a variable magnetic field, or an alternating electric field. A method for producing high freshness frozen raw vegetables. The method for producing fresh fresh frozen vegetables according to any one of claims 1 to 5, wherein an ionic wind is superposed on the cold air in the freezer. A fresh fresh frozen vegetable prepared by the method for producing fresh fresh frozen vegetables according to claim 1.

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