Freezer and freezing mechanism using latent heat infrared reflection

Abstract

According to the present invention, by disposing an infrared reflecting plate for reflecting 98% or more of latent heat infrared rays on the entire inner surface of a freezing chamber, the latent heat infrared rays generated during freezing are reflected back to the food surface, and thus freezing at the surface is delayed and freezing starts from the inside. As a result, the freezing expansion inside the food is absorbed by an unfrozen surface layer part, thereby improving the freezing quality.

Description

Latent heat infrared reflection freezer and freezing equipment

[0001] The present invention relates to a technique for freezing water-containing materials by reflecting the latent heat radiation of the material back to the surface.

[0002] Traditionally, heat transfer near room temperature is primarily via fluid convection and thermal conduction through contact, with radiation being a minor factor. Furthermore, because radiant energy in the case of a blackbody is proportional to the fourth power of the surface temperature of the radiator, it was thought to be ineffective unless the surface temperature of the radiator exceeded several hundred degrees Celsius. Furthermore, it was thought that infrared radiation had almost no effect on heat dissipation or absorption near the freezing point of low-temperature water or food. It was also known that the surface of food sometimes supercools and freezes at temperatures between -15°C and -20°C. Supercooling freezing results in high-quality freezing with minimal dripping. Supercooling deeper into the food allows for better quality freezing. Thin foods are particularly susceptible to supercooling, and thin foods often become supercooled and freeze all the way to their centers. For this reason, household refrigerator freezers often use freezer boxes or shelves made of low-thermal-conductivity plastic to insulate the cold and facilitate supercooling.

[0003] Japanese Patent Application Laid-Open No. 2015-183933 Japanese Utility Model Application Laid-Open No. 60-171192

[0004] Due to energy costs and the working environment of workers, the temperature inside a freezer is generally kept around -20°C, and thick foods are frozen slowly. Because food, especially fresh foods, has a high moisture content, the conventional theory is that damage to cellular foods occurs when the food's core temperature remains in the maximum ice crystal formation temperature range, from the food's freezing point (near 0°C) to -5°C, for a long time. This causes the moisture in the food to gradually form ice crystals, which grow in size and damage the cell membranes. The subsequent instantaneous expansion caused by freezing destroys the cell membranes, which is thought to deteriorate the quality of the freezing process.

[0005] Furthermore, even though it was known that supercooling freezing reduces dripping, it was not possible to reliably supercool and freeze all foods. Therefore, a method for reliably freezing with good freezing quality was sought. Furthermore, until now, there was no quantitative measurement method for determining which freezing method reduces dripping, so detailed comparisons were not possible.

[0006] As will be explained in more detail later, the inventor discovered a method for quantifying the quality of freezing and made comparisons. When comparing foods of the same shape, weight, and quality at the same ambient temperature (hereinafter referred to as "cabinet temperature"), with the same air speed, the same thermal conductivity and contact area of ​​the contacting object, and using a method such as reflecting the latent heat radiation infrared rays with a reflective material and returning them to the surface of the food to be frozen, he discovered that the longer the time from the start of latent heat release to the completion of freezing (hereinafter referred to as "required freezing time"), the less dripping there would be after thawing. This hypothesis was thought to have become the accepted theory because, according to the conventional theory, when food is frozen at a cabinet temperature set at the maximum ice crystal formation temperature range of -5°C from the freezing point, the amount of dripping after thawing increases. However, in typical food freezing, the temperature inside the freezer is kept below -18°C, and food is cooled solely by the air inside the freezer, such as by placing a rack on the freezer. Conversely, when using methods such as those described above to extend the required freezing time, the latent heat release time is extended, resulting in the formation of more ice nuclei within the food. This shortens the time from the start of freezing (when the ice nuclei become nuclei after the latent heat release ends and crystallization begins) to the completion of freezing (hereinafter referred to as "freezing time"), which is thought to improve the quality of freezing. In conventional freezing, the surface freezes first, followed by the interior, destroying the already frozen surface layer due to the internal freezing expansion. However, with this method of freezing by reflecting latent heat infrared rays using a reflective material, the freezing of the food surface is delayed, allowing ice crystals to form within the food, which then begins freezing from the inside, and the unfrozen surface layer absorbs the internal freezing expansion, improving the quality of freezing. Therefore, a reliable method is needed to shorten the freezing time of food and extend the latent heat release time.

[0007] In Patent Document 1, a metal mesh is provided on the inner surface of a heat transfer plate in a freezer, and frost is formed on the metal mesh to prevent frost from forming on the heat transfer plate.

[0008] In Patent Document 2, fin-like protrusions are provided on the surface of the shelves or conveyor that come into contact with the bottom surface of the food, thereby increasing the contact area between the cooling air and the food.

[0009] However, in Reference 1, frost does not form on the heat transfer plate, but does form on the inner metal mesh, which absorbs latent infrared radiation from the food. It is necessary to constantly remove the frost from the metal mesh by physical means. In Reference 2, an aluminum bottom, shelf, and spacers are provided. However, frost forms on these surfaces when outside air enters, absorbing latent infrared radiation.

[0010] Latent infrared radiation is radiation emitted at the freezing temperature of food, around 0°C. Because the radiation intensity is weak due to the surface temperature of the food, if frost, condensation, fog, or frost is present between the food and the reflective material, the radiation is absorbed and hardly reaches the food, posing a major issue. When food is stored in a bag or container at room temperature, air with high absolute humidity is also stored, which can lead to frost, condensation, fog, and frost formation during cooling and freezing. Furthermore, when food is taken out of a freezer and the door is opened, air with high absolute humidity enters the upper part of the freezer. This intrusion causes fog and frost to form in the upper part of the freezer, as well as condensation and frost on the ceiling, side walls, and upper shelves.

[0011] When foods made of hydrated organic matter are cooled to their freezing point, they begin to release latent heat. In the case of pure water, the release of latent heat keeps the water temperature at 0°C, the freezing point of water, and transfers and releases latent heat to the surrounding water and the cooled air in contact with the surface via three means: conduction, convection, and radiation. In the case of slow freezing at atmospheric pressure, the freezing point drops in the presence of solutes according to their molar concentration. During ice nucleation during latent heat release, only pure water crystallizes, and the solute is pushed into the surrounding liquid, increasing its solute concentration. Therefore, the cooling curve for latent heat release is not horizontal, but rather a straight line sloping downward at an angle depending on the concentration and cooling rate. However, the mechanism of latent heat release is the same as that of pure water. Traditionally, radiant energy was considered to be proportional to the fourth power of the absolute temperature of the object's surface, and therefore virtually negligible as a means of heat transfer at low temperatures.

[0012] However, at room temperature (20°C), it is 293K, and at 0°C it is 273K, which is about 1.07 times higher, and even if you raise this to the fourth power, the energy is only 1.3 times higher. In other words, even around 0°C, the radiation intensity and radiation energy are not significantly different from room temperature, so they cannot be ignored as a heat transfer method. Also, like other heat transfer methods, infrared absorption and radiation depend on the difference between the temperature inside the refrigerator (hereinafter "Te") and the surface temperature of the object to be cooled (hereinafter "Ts"); when Te > Ts, absorption predominates and absorption occurs; when Te = Ts, radiation and absorption are balanced; and when Te < Ts, radiation predominates and radiation occurs.

[0013] The role of radiation in the freezing process is important, depending on the temperature difference between the object and the environment as well as the temperature of the object. When latent heat is released, Te > Ts is always true. The water in the object releases latent heat, forming ice nuclei and radiating latent heat infrared rays to the surroundings. Meanwhile, inside food, the peak absorption wavelength of ice crystals at 0°C and the peak radiation wavelength of water are nearly identical. When ice nuclei form due to external cooling, they radiate latent heat infrared rays to the surroundings. The surrounding ice nuclei melt as they absorb the radiated latent heat infrared rays. Ice nuclei formed on the surface of the object by cooling are transported to the interior, where they melt due to the absorption of latent heat radiation, repeating this cycle. As long as Te < Ts is true, ice nuclei increase from the surface to the interior. The internal latent heat is transported to the surface and dissipated from the surface by contact conduction, convection, and radiation. When the ice nuclei accumulate to a saturation level, they become nuclei and crystallization begins. The water, which had been liquid until then, begins to freeze as it releases more latent heat, and once it starts to freeze, it undergoes a rapid phase transition to a solid from the point where freezing began.

[0014] The more ice nuclei there are in the frozen food, the higher the density of ice nuclei, and the faster the speed from the start of freezing to the end of freezing (hereinafter referred to as the "freezing rate"). Conversely, if the same food is frozen at a high temperature inside the freezer and a slow cooling rate, the latent heat release time will be longer. However, rather than increasing the number of ice nuclei, the ice nuclei will bond locally, resulting in a longer time from the start of freezing to the end of freezing (hereinafter referred to as the "freezing time"), which is thought to result in larger ice crystals and damage to the cells. The infrared radiation wavelengths of 8 to 15 μm (hereinafter referred to as "latent heat infrared"), which are the main radiation wavelengths during latent heat release and absorption, are in the long-wavelength infrared range. When the temperature, humidity, and airflow inside the freezer and the quality, size, shape, weight, and moisture content of the food are the same, reflecting latent heat infrared radiation from the outside and absorbing it into the frozen food extends the latent heat release time of the surface layer compared to non-reflecting radiation. This results in the formation of more ice nuclei than saturated ice nuclei in the frozen food, shortening the freezing time, suppressing the growth of ice crystal size, and enabling high-quality freezing. The inventors have discovered that by measuring the amount of dripping using konjac, it is possible to quantitatively compare the quality of freezing, and that extending the latent heat release time by reflecting the latent heat infrared rays back onto the surface of the hydrated organic matter to be frozen results in better quality freezing with less dripping after thawing.

[0015] The means for reflecting the latent heat infrared rays emitted by the frozen item reflects them one or more times until they reach the item. A material with high reflectivity for latent heat infrared rays is required. A reflectivity of 80% or more in this wavelength range at around 0°C is desirable. Mirror-finished pure aluminum, copper, silver, or gold all have a reflectivity of 90% or more in this wavelength range. Conventionally, the materials used for the interior walls of freezers and prefabricated freezers have been stainless steel plates, colored steel plates, or colored aluminum plates, but these have high emissivity and insufficient reflectivity for long-wavelength infrared rays and far-infrared rays in the wavelength range of latent heat infrared rays. Note that alloys of metals with high reflectivity may also be used.

[0016] The present invention features a freezer comprising a container for storing water-containing organic matter, a cooling device for directly or indirectly cooling the inside of the container, a reflector for reflecting long-wavelength infrared rays emitted from the water-containing organic matter when frozen back to the water-containing organic matter, and an anti-frost device for preventing frost from forming on the reflector.

[0017] The water-containing organic matter may be stored in the freezer container in an uncovered state, or may be stored in the freezer container wrapped in a packaging material with high latent heat infrared transmittance, such as polyethylene film. The water-containing organic matter is not particularly limited, and examples thereof include food such as meat, fish, and vegetables, fresh flowers, and cell tissue.

[0018] The container may have a storage space partitioned by walls, a ceiling, and a floor, and may have shelves arranged inside the storage space for freezing the water-containing organic matter.

[0019] The reflectors may be provided on at least a portion of the walls, ceiling, and floor of the storage space and on the front and back surfaces of the freezer shelf. The reflectors reflect long-wavelength infrared rays emitted from the water-containing organic matter when the water contained in the water-containing organic matter releases latent heat during the freezing process to the surface layer of the water-containing organic matter.

[0020] Examples of anti-frost devices include a heating anti-frost device for the reflector to prevent frost from forming on the surface of the reflector due to the intrusion of outside air, a device that blows air onto the reflecting surface of the reflector, or an intrusion outside air dehumidifier.

[0021] By providing long-wavelength infrared reflectors on the walls, ceiling, floor, shelves, and interior doors of a freezer where frozen items are frozen, the latent heat infrared radiation emitted from the surface of the frozen items can be reflected back to the frozen items' surface, extending the latent heat release time and improving freezing quality. Items are stored in the freezer naked or in polyethylene film freezing bags, wrapping film, or vacuum-sealed bags. Low-density polyethylene film has an exceptional absorption rate of 30-40% at wavelengths of approximately 14 μm in the long-wavelength infrared range, with nearly 100% transmittance at other wavelengths. Reflectors with high near-infrared reflectivity, such as mirror-finished metal plates, foils, or metal plating, made of aluminum, tin, silver, gold, titanium, platinum, nickel, molybdenum, copper, or alloys of these, can be used as the reflective surface, reflecting weak latent heat infrared radiation back to the food. In addition, heating or blowing air onto the reflecting plate of the reflective material can prevent frost and condensation, and dehumidifying the invading outside air beforehand can suppress the formation of fog and frost. The air blower can help prevent frost from forming on the reflective material when outside air enters when the door is open, further improving refrigeration efficiency. When an air mass that generates fog or frost due to the intrusion of outside air containing a large amount of water vapor comes into contact with the reflective material, frost forms. However, since the remaining air inside the refrigerator is undersaturated, blowing the undersaturated air can sublimate the frost and reflect latent heat infrared rays. Furthermore, a shelf can be provided in which the reflective material is inclined relative to the direction of air blowing from the air blower. With the above configuration, the wind speed on the surface of the reflective material can be accelerated, helping to prevent frost from forming on the reflective material and further improving refrigeration efficiency.

[0022] When food is frozen, it emits infrared radiation with a peak wavelength of approximately 10.6 μm. By returning this latent heat radiation to the surface of the food, ice nucleation on the surface is suppressed, delaying freezing of the surface and initiating freezing from the inside. This allows the unfrozen surface layer to absorb the expansion pressure of the expanding interior, thereby suppressing cracking and improving freezing quality. If a 10 μm-thick water layer is present on the surface of the food, assuming infrared radiation penetrates, each material has its own characteristics regarding the wavelengths emitted and absorbed. Specifically, ice nuclei are more likely to emit and absorb infrared radiation at 9.8 μm, while unfrozen water is more likely to emit and absorb infrared radiation at 14.5 μm. Overall, wavelengths around 10.6 μm are most strongly emitted. During thawing, thawing proceeds by absorbing infrared radiation at 9.8 μm.

[0023] To utilize this radiation and reabsorption of latent heat infrared rays, it is desirable to use an appropriate infrared reflector that efficiently returns infrared rays emitted from the food to the food surface. It is preferable to use a material for the reflector that has a reflectivity of 80% or more for infrared rays with wavelengths of 9 to 15 μm, and particularly a high reflectivity of 95% or more, and more preferably 98% or more, for wavelengths of 9 to 11 μm. This promotes the reabsorption of latent heat infrared rays, facilitating ice nucleation and improving freezing quality.

[0024] Actual reflectors include mirror-finished metal plates, metal foils, metal-deposited films made of aluminum, silver, copper, or alloys thereof. In particular, materials that exhibit high reflectance in the wavelength range of 9 μm to 15 μm match the infrared absorption characteristics of unfrozen water and are advantageous in terms of re-absorption efficiency.

[0025] Regarding the placement of the reflector, the distance from the food surface has a significant effect on the reflection efficiency. For example, when wrapping food in aluminum foil, the distance to the reflector is short, ranging from a few mm to a few cm, and the number of reflections is short, so there is little loss of infrared light. However, there is a thin oxide film on the aluminum surface, which absorbs several percent of the infrared light with each reflection. Furthermore, with aluminum that is not mirror-finished, the reflection intensity can be reduced by nearly 20% with each reflection due to diffuse reflection, scattering, and absorption.

[0026] On the other hand, when reflective material is used on the walls of a freezer, the distance from the food is large, and infrared rays are reflected many times before reaching the reflective material and returning to the food surface, resulting in significant attenuation of infrared intensity, and ordinary aluminum plates cannot provide sufficient reflective effect. Therefore, it is desirable to use a high-performance reflective material with an infrared reflectance of 98% or more at wavelengths of 9 to 11 μm.

[0027] In the present invention, the freezer has a double structure with the walls and ceiling sandwiching a gap space, and the cooling device cools the interior of the freezer by cooling the gap space, or a refrigerant pipe installed on the back side of the ceiling or wall may be arranged to cool the interior of the freezer from the back side, thereby indirectly cooling the inside of the storage body.

[0028] The cooling device may be configured to directly cool the storage space using a cooler installed inside the storage unit, or it may be configured to indirectly cool the storage space by circulating a refrigerant through refrigerant pipes installed on the walls or behind the top of the storage unit. In the former case, the cool air circulation system can make the temperature inside the storage unit uniform, while in the latter case, low-temperature radiation from the walls has the advantage of maintaining a high humidity environment while mitigating the influence of outside air when the door is opened and closed, and preventing the surface of food from drying out.

[0029] In order for the reflector to function properly, it is preferable to prevent frost from forming on the reflective surface. For this reason, it is recommended to use a combination of anti-frost devices, such as heating the reflective surface with a heater, forced airflow when the door is opened and closed, or pre-dehumidification of the air entering the refrigerator. In particular, in environments where the door is opened and closed frequently, the installation of a pre-chamber type dehumidifying space is effective because it significantly reduces the risk of frost formation.

[0030] In freezers with a built-in cooler, dehumidification occurs when the cooler is running, and heat enters through the walls and ceiling, causing the temperature inside the freezer to rise above the temperature inside the freezer. This prevents frost from forming on the walls unless the door is open. However, in storage and high-humidity freezers, refrigerant pipes are placed on the top or behind the walls, or the walls and ceiling are double-layered to cool the gaps. While this prevents the freezer from drying out due to the lack of a cooler inside the freezer, frost still forms on the walls and ceiling because the temperature inside the freezer drops below the temperature inside the freezer. Frost formation is particularly pronounced when high-absolute-humidity outside air enters the freezer when the door is open. Therefore, heating the walls and ceiling removes frost and allows for a high degree of reflection of the latent heat infrared radiation emitted from the food, resulting in high-quality freezing.

[0031] The antifrost device may include a heating means using a transparent or thin heating film, heater wire, or infrared irradiator attached to the surface of the reflector. Also suitable are a system that uses a blower that is activated when the door is opened and closed to agitate and exhaust excess humidity air in the upper part of the refrigerator, or a humidity control system that uses a front chamber. This quickly removes frost and frost that form on the reflector surface and prevents a decrease in infrared reflection efficiency.

[0032] The cooling method for the interior of the refrigerator can be either a direct cooling method, in which cold air is circulated directly from a cooler installed inside the refrigerator, or an indirect cooling method, in which the interior walls are cooled, but the indirect cooling method is particularly preferable as it makes it easier to maintain a high humidity environment and minimizes drying of food surfaces.When using the indirect cooling method, reflectors can be placed on the interior walls, which reduces the risk of frost forming on the direct cooler and improves equipment maintainability.

[0033] In the present invention, the reflector heating frost prevention device may heat the reflector surface by irradiating it with infrared rays.

[0034] By using an infrared irradiator as the heating means and irradiating from the outside, the irradiating location can be easily changed by changing the angle and position of the irradiator, and furthermore, management and maintenance become easy.

[0035] In the present invention, the reflector heating frost prevention device may heat the gap space.

[0036] When the temperature in the gaps is lower than the temperature inside the cabinet, frost forms on the interior walls and ceiling. By heating the gaps, ceiling, and walls, the frost can be melted and poured into the drain, or by using an internal fan to blow air through the cabinet to evaporate it, thereby eliminating the frost.

[0037] In the present invention, the reflector heating frost prevention device may heat the refrigerant pipes by flowing a heat medium having a temperature higher than the temperature inside the refrigerator through the refrigerant pipes installed on the rear surface.

[0038] By providing a heating means on the rear surface of the reflector of the present invention, the internal volume of the container can be used effectively.

[0039] In the present invention, a hole or an opening may be provided in the wall surface or the top surface to allow the air in the gap space to communicate with the air inside the refrigerator.

[0040] In freezers that do not have a storage unit or internal cooling unit, frost forms on the inner walls because the cooling is done from the surrounding walls. However, by providing holes or openings in the walls that connect to the backside, the temperature difference on both sides of the wall is reduced, preventing frost from forming.

[0041] In the present invention, the heating and frost prevention device and the air blower may operate when the door of the freezer that is in contact with the outside air is open, and may stop heating after a desired time period using a timer.

[0042] This method allows the heating and frost prevention device and the air blower to be controlled by a timer, thereby maintaining a stable temperature inside the refrigerator and reducing power consumption. In particular, controlling the heating and frost prevention device can minimize the effects of infrared radiation on food. Furthermore, controlling the air blower can prevent uncovered food from drying out.

[0043] In the present invention, the freezer may be provided with a front chamber, and the air in the front chamber may be dehumidified.

[0044] By using a dehumidifier in the front room to reduce the humidity in the front room, it is possible to prevent high absolute humidity outside air from directly entering the room when the door is open, thereby suppressing the formation of frost and frost inside the room.

[0045] In the present invention, the storage body may have a mesh shelf where the surface of the shelf that comes into contact with the food is mesh-like, and a position adjustment mechanism that can change the installation height of the reflective material from the food relative to the water-containing organic matter placed on the mesh shelf.

[0046] By placing a reflective material above the food, if the back side of the reflective material is also reflective, and if there are multiple shelves, the infrared radiation emitted downward by food on the shelf above the wire rack can be reflected, returning it to both the top and bottom of the food. In this case, the reflective material must be placed as close to the food as possible, because the radiation intensity and reflection intensity are inversely proportional to the square of the distance between the food and the reflective material. For tall shelves, it is more effective to place reflective material not only on the top of the wire rack but also on the bottom. In other words, by placing two reflective plates on the top of the rack, the reflective material can be placed closest to the food vertically, enabling more effective and high-quality freezing. While the placement can be changed, this allows foods of different sizes to be frozen under optimal conditions.

[0047] In the present invention, a reflector for use when freezing on a belt conveyor can be provided in which a latent heat infrared reflector is provided in contact with or near a portion of the food surface, and the latent heat infrared rays emitted by the food during freezing are reflected and returned to the food surface, as shown in Figure 13. Furthermore, in a freezing method in which food is frozen while being moved on a belt conveyor, a latent heat infrared reflector may be provided on the surface of the belt conveyor that comes into contact with the food, or a reflector may be vapor-deposited or applied.

[0048] Blast freezing involves blowing cold air around the food to freeze it, but freezing the food so that the entire food is wrapped in cold air increases the freezing rate, but after the surface freezes, the interior freezes and expands, causing damage that causes cracks in the frozen surface. However, by making sure that part of the surface freezes last, the freezing that begins on the other surfaces progresses toward the final frozen part, minimizing this damage.

[0049] In this regard, the present invention can also be applied to a continuous freezing process using a belt conveyor, as described above. That is, when freezing food by means of blowing cooled air onto the food while it is being transported on a belt conveyor, the latent infrared heat radiated from the food surface is reflected again, cooling the food while suppressing ice nucleation in the surface layer, promoting ice nucleation in the interior, and allowing freezing to begin from the inside, thereby absorbing the internal expansion pressure with the unfrozen surface layer, thereby improving freezing quality.

[0050] In the configuration of the present invention, it is preferable to provide an infrared reflective material on the surface of the belt conveyor located below the food or on the underside structure near the belt conveyor. As the reflective material, a mirror-finished metal foil, a metal-deposited film, or an infrared reflective paint having a high reflectivity (preferably 95% or more, more preferably 98% or more) in the infrared wavelength range (particularly 9 to 11 μm or 8 to 15 μm) as described above is used. These may be directly attached, vapor-deposited, or applied to the belt surface, or may be attached as a support to the conveyor lower structure.

[0051] When food is frozen while moving on a conveyor belt, the latent infrared heat emitted by the food tends to leak under the belt and into the surrounding area, resulting in a high percentage of it being lost before being reabsorbed. Therefore, by installing an infrared reflector on the underside of the belt, the radiated infrared light can be effectively reflected back toward the food surface, stably inducing ice nucleation during freezing. In particular, reflecting radiation from the underside of the food allows the underside to freeze last, controlling the direction of freezing, reducing surface cracks, and minimizing ice crystal size.

[0052] Furthermore, in belt conveyor-type freezing devices, it is common to install a cooling unit that blows cooling air (cold air) from above and the sides. In addition, by using an infrared reflector in combination with this, it is possible to achieve both cooling efficiency and freezing quality.

[0053] The material used to make the belt must take into consideration its flexibility and cold resistance as a conveying mechanism, but by integrating a reflective material into the belt (by laminating, coating, vapor deposition, etc.), it is possible to create a belt conveyor with infrared reflective properties.

[0054] Next, the freezing bag of this embodiment will be described.

[0055] In the present invention, the frozen material contains a water-containing organic material that is damaged by the freezing expansion of water when frozen, and when the latent heat of freezing of the water in the organic material is released, latent heat infrared rays, which are infrared rays in the wavelength range of the latent heat of freezing radiation of water at the freezing point from the surface layer of the organic material, are reflected back to the surface layer of the organic material by a latent heat infrared reflective material, and the latent heat infrared rays are frozen while being absorbed by the surface layer of the food, and the bag or container is characterized by having a means for removing the air inside, and further having a convex portion on one side of the outer surface of the reflective material.

[0056] The shape of the freezer package is not particularly limited and may be a bag or a container.

[0057] By removing the air from inside the bag or container, it is possible to remove the high absolute humidity water vapor that entered the bag or container when storing food indoors, suppressing frost formation on the surface of the frozen item during freezing and allowing latent heat infrared rays to reach the surface of the frozen item, enabling high-quality freezing. Furthermore, by providing a convex portion on one side of the exterior of the bag or container, when the temperature inside the freezer is high (e.g., -18°C or higher), freezing can be performed with the convex portion facing down, enveloping the bottom of the bag or container in cold air, enabling higher-quality freezing. When the temperature inside the freezer is low (e.g., -25°C or lower) and freezing is performed by contacting pre-cooled metal, freezing by directly contacting the metal foil surface without the convex portion shortens the time from start to completion of freezing, enabling better freezing.

[0058] The freezer packaging may also have a base layer and a reflective material layer provided on the base layer. The reflective material layer may be arranged so as to face at least the water-containing organic matter. Specifically, the outer layer may be the base layer and the inner layer may be the reflective material layer, or the outer layer may be the reflective material layer and the inner layer may be the base layer. Note that when the outer layer is a reflective material layer, by using a base layer that is transparent to latent heat infrared rays, the surface of the reflective material layer in contact with the base layer faces the water-containing organic matter. Note that the layer located on the outside of the packaging is referred to as the outer layer, and the layer located on the inside of the packaging is referred to as the inner layer.

[0059] In addition, any other layer may be provided outside the outer layer or inside the inner layer, or any intermediate layer may be provided between the outer layer and the inner layer. For example, when the inner layer is a reflective material layer, the innermost layer may be provided with a resin layer that is transparent to latent heat infrared rays so that the reflective material layer does not come into direct contact with the water-containing organic matter. Furthermore, any intermediate layer may be provided from the viewpoint of improving adhesion, etc.

[0060] The convex portions are provided on at least one outermost surface, preferably the outermost layer. The convex portions may be provided on a substrate layer or a reflective material layer that has been embossed or otherwise textured.

[0061] The surface of the reflector facing the frozen product is preferably a mirror finish, which is excellent in improving reflectance, since, for example, the long-wavelength infrared reflectance of mirror-finished aluminum is about 98%, while the long-wavelength infrared reflectance of ordinary untreated aluminum is about 82 to 90%.

[0062] The latent heat infrared rays may include long-wavelength infrared rays having a wavelength of 9 to 15 μm, and the long-wavelength infrared rays preferably include a wavelength range of 9.8±2 μm or 14.5±2 μm. Since ice nuclei have a high absorptivity for long-wavelength infrared rays around 9.8 μm, it is preferable to thaw them by absorbing infrared rays with a wavelength of 9.8 μm. Note that water has a high absorptivity for long-wavelength infrared rays around 14.5 μm.

[0063] In the present invention, the frozen material contains a water-containing organic material and is damaged by the freezing expansion of water when frozen, and when the water in the organic material releases latent heat, latent heat infrared rays, which are infrared rays in the wavelength range of the latent heat radiation of water at the freezing point from the surface layer of the organic material, are reflected back to the surface layer of the organic material by a latent heat infrared reflective material, and the food is frozen while being absorbed by the surface layer, and the freezing method bag or container is characterized in that a water-containing layer is provided inside the reflective material.

[0064] By providing a layer containing water (hereinafter referred to as the "water layer") between the reflective material and the object to be frozen, the temperature of the water layer is maintained at 0°C until it freezes. During the period until the water layer freezes, the object to be frozen is pre-cooled at 0°C, making it easier for it to become supercooled by keeping it at 0°C all the way to the core. By adding alcohol or salt to the water or water-retaining material, or by changing the ingredients or composition of the water-retaining material, the freezing temperature of the water layer can be made below 0°C, and it can be adjusted to match the freezing temperature of the object to be frozen.

[0065] In the present invention, the frozen material contains a water-containing organic material and is damaged by the freezing expansion of water when frozen, and when the water in the organic material releases latent heat, latent heat infrared rays, which are infrared rays in the wavelength range of the latent heat radiation of water at the freezing point from the surface layer of the organic material, are reflected back to the surface layer of the organic material by a latent heat infrared reflective material, and the latent heat infrared rays are frozen while being absorbed by the surface layer of the food, and the frozen material is placed inside a bag made of polyethylene film with air removed inside the reflective material.

[0066] For example, the freezer package may have an exterior body having a base material layer and a reflective material layer, and an interior body made of a resin film that is separate from the exterior body and disposed inside the exterior body. In this case, the frozen material is contained in the interior body.

[0067] By storing frozen items wrapped in an inner bag made of polyethylene film with air removed or wrapping film inside a latent heat infrared reflective bag or container, high-quality thawing can be achieved by removing the inner bag when thawing.

[0068] The present invention is characterized in that the reflector is provided with a communication hole or slit that allows ventilation to the outside.

[0069] By making holes or slits in the bags or containers that allow communication with the inside, it is possible to remove high absolute humidity air that gets mixed in when frozen items are stored indoors inside the freezer, preventing frost from forming on the frozen items and enabling high-quality freezing.

[0070] The present invention is characterized in that a layer of polyethylene film is provided between the reflective material and the object to be frozen.

[0071] By disposing a polyethylene film on the layer that comes into contact with the frozen material, it is possible to prevent the frozen material from adhering to the bag or container during freezing.

[0072] Tables 3B and 4, showing the experimental results described below, show that samples frozen in aluminum foil packaging dripped less than samples packaged in vinylidene chloride film. Furthermore, samples pre-cooled and then wrapped in aluminum foil and frozen on a rack exhibited the least amount of drip. It was also known that slow freezing at temperatures between -15°C and -25°C can result in supercooling and freezing, resulting in very high-quality freezing. However, even placing a rack under thick foods such as meat or fish or using a slow cooling rate has proven difficult to achieve 100% supercooling and freezing. However, by extending the latent heat release time by returning latent heat infrared rays to the food surface as in the present invention, high-quality freezing can be achieved. Furthermore, suppressing frost formation on the reflective material and reducing the distance between the reflective material and the food minimizes the attenuation of the latent heat infrared intensity returning to the food, thereby extending the latent heat release time and achieving high-quality freezing.

[0073] Graph showing experimental results for explaining the present invention. Explanatory side cross-sectional view explaining an experimental method of the present invention. Explanatory side cross-sectional view showing experimental results for explaining the present invention. Explanatory side cross-sectional view showing experimental results for explaining the present invention. Explanatory side cross-sectional view showing a top panel and a freezer of an example of this embodiment. Explanatory side cross-sectional view of a side wall panel and a freezer of an example of this embodiment. Explanatory side cross-sectional view of a side wall panel and a frost sensor of an example of this embodiment. Graph showing experimental results for explaining an example of this embodiment. Explanatory plan cross-sectional view of a freezer with a front chamber of an example of this embodiment. Explanatory side view of a freezing shelf of an example of this embodiment. Graph of konjac drip amount. Schematic cross-sectional view showing a belt conveyor of an example of this embodiment. Explanatory side cross-sectional view of a freezing bag of an example of this embodiment. Explanatory top view of a freezing bag of an example of this embodiment in Figure 13. Explanatory view of an air vent plug of another type for the freezing bag. Explanatory cross-sectional view of a freezing bag of another example of this embodiment. Explanatory top view of a freezing bag of another example of this embodiment. Graph showing experimental results for explaining the present invention.

[0074] Hereinafter, an embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present disclosure is not limited thereto and various modifications are possible without departing from the spirit thereof. In the drawings, the same elements are given the same reference numerals and redundant explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0075] The explanation will be given using Figures 1 to 10. The mechanism of this discovery was estimated through Experiments 1 and 2. Furthermore, prior to these experiments, a new simple method for measuring the amount of dripping was developed, as quantifying the quality of freezing had previously been difficult.

[0076] In a measurement method previously developed by the inventor, agar was frozen and thawed in a low-G environment using a centrifuge and drip filter, and the drip weight was compared. However, this method required an old-fashioned centrifuge in which the sample storage bucket could be freely adjusted in angle relative to the rotor. Thawing was only possible in an environment where centrifugal force was constantly applied. This is because agar has the property of reabsorbing drips once released and returning to its original state. Currently, this old-fashioned centrifuge is no longer commercially available, and can only be custom-made, making it difficult to generalize this measurement method. Another drawback of this agar drip measurement method is that it can only measure samples that fit into the small centrifuge bucket.

[0077] Therefore, flat konjac (hereinafter "flat konjac") from the same manufacturer and on the same production date was cut into shapes and frozen, then thawed at room temperature in a thawing hotel pan on a rack, covered with plastic wrap, and the drip weight was measured to compare the drip rates. Konjac is easy to obtain and process, and has little variation, making it convenient for comparing multiple types at once. Furthermore, because konjac requires an alkaline solution to solidify, it does not absorb the drip and return to its original shape. For comparisons, cutting multiple samples from a single flat konjac ensures the least variation in quality. When screening different flat konjac, avoid buyer's brands and use products with the name of the konjac specialty manufacturer and the expiration date, and use products from the same manufacturer with the same expiration date to minimize variation in drip rates.

[0078] As shown in Figure 11, experiments were conducted to determine the best time point for thawing konjac for this measurement method, at room temperature, beyond the time required for complete thawing. It was found that the least variation occurs when measuring after waiting for a time constant of 2τ or more (10 hours or more) and 3τ or less (16 hours or less), assuming that the drip rate after 24.5 hours is 100%. The difference in drip rate between konjac packaged in aluminum foil and konjac packaged in wrapping film is greatest after 12 hours, and there is not much difference in drip rate for the four hours before and after that, but after 16 hours the difference in drip rate becomes so small that it cannot be ignored.

[0079] [Experiment 1] To understand how freezing actually occurs, 40 ml of water (203) was placed in a stainless steel container with a space above and below it between pre-cooled duralumin plates with an anodized aluminum surface, which has a high infrared radiation absorption effect, as shown in Figure 2. The container was then sandwiched between disposable chopsticks (205) on a wooden rack at the bottom and frozen in a storage container at -20°C (hereafter referred to as "anodized aluminum"). At the same time, similar water was placed in the same storage container and frozen between the mirror-like surfaces of pre-cooled aluminum foil, which has a high infrared radiation reflection effect (hereafter referred to as "aluminum"). The cooling curve for this water is shown in Figure 1. Schematic diagrams showing the ice surface shape after freezing are shown in Figures 3 and 4.

[0080] The apparatus shown in Figure 2 consists of a metal container (202) containing a predetermined amount of water (203), sandwiched between an upper test plate (201) and a lower test plate (206). The upper and lower test plates may be made of different surface-treated materials (e.g., mirror-finished aluminum foil, anodized aluminum, etc.) that alter their infrared reflection or absorption characteristics. A wooden spacer (205) is inserted into the bottom of the stainless steel container (202) to ensure space between the container and the lower test plate (206) to prevent direct contact. During the test, a thermocouple sensor (not shown) is inserted into the water in the center of the container to measure temperature changes over time. This configuration allows for the comparison of the effects of differences in infrared radiation from the top and bottom surfaces on the freezing behavior of water. This device configuration allows for clear evaluation of differences in cooling curves, freezing times, and freezing behavior due to differences in the conditions under which infrared light is reflected and absorbed by the water surface during latent heat release.

[0081] A thermocouple sensor was fixed near the center of the water in the stainless steel container and measurements were taken. The anodized aluminum and aluminum water samples were simultaneously placed in the storage container and measurements were initiated. The latent heat release time was defined as the time from when the water temperature at the sensor reached 0°C (103, 102) to when it dropped below 0°C (105, 104). The maximum ice crystal formation zone residence time was defined as the time from when the water temperature at the sensor dropped from 0°C to -5°C. The solidification time was defined as the time from when the water temperature at the sensor dropped below 0°C (hereinafter referred to as the "freezing start time") to when freezing was complete. Because the sample volume was small (40 ml), if latent heat was released somewhere within the water in the container, this effect would cause the downward slope of the cooling curve to decrease even after freezing began at the sensor. However, once all the water in the container froze, the effect of latent heat disappeared, resulting in a steeper downward slope and an inflection point on the curve. This point (107, 106) was defined as the freezing completion point. Table 2 shows the results for Figure 1. Here, the results showed that the longer the residence time in the maximum ice crystal formation zone, the shorter the solidification time. However, this contradicted the conventional theory, so the frozen samples were observed.

[0082] In the device shown in Figure 2, when aluminum was used as the metal container (202), the ice (303) froze with a raised center (302) of the ice surface, as shown in Figure 3. On the other hand, when anodized aluminum was used as the metal container (202) in the device shown in Figure 2, the ice (403) froze with a horizontal ice surface (402), as shown in Figure 4.

[0083] From these findings, it is presumed that with aluminum, the latent infrared rays from the water were reflected by the pre-cooled aluminum foil and returned to the water surface, where they were reabsorbed by the water, delaying the start of freezing on the water surface and causing freezing to begin from the bottom and sides in contact with the container. Furthermore, with anodized aluminum, the latent infrared rays from the water were absorbed by the pre-cooled anodized aluminum and did not return to the water surface, or the strength of the returning infrared rays was low, so it is thought that freezing began from the water surface in direct contact with the cooling air. Because the freezing start and completion positions differ for both samples relative to the sensor position, it is impossible to say anything based on the results in Table 2 alone; therefore, Experiment 2 was conducted so that the freezing start and completion positions would be the same.

[0084]

[0085] [Experiment 2] Two samples of konjac cut into shapes and wrapped with vinylidene chloride resin wrapping film (hereinafter referred to as "wrapped") were placed in the freezer compartment of a household refrigerator. Another sample of konjac wrapped with aluminum foil, with the mirror side facing inward (the konjac side), was placed on an insulating sheet placed on the floor of a resin freezer to minimize the influence of the floor. The next day, the samples were placed on the rack of a thawing device covered with plastic wrap and left at room temperature for 15 hours. After thawing, the samples were weighed, and the drip rate (Table 3A) was calculated from the difference from the initial weight. A thermocouple was inserted into the center of the konjac, and the cooling curve (Figure 8) was obtained. Both samples were simultaneously placed in the freezer compartment of a household refrigerator at temperatures ranging from -18°C to -20°C.

[0086] Figure 8 is a graph showing characteristic points on the cooling curve in Experiment 2. 801 indicates the measurement start point, 802 (wrapped in plastic wrap) and 803 (wrapped in aluminum foil) indicate the start of latent heat release from the sensor, 804 (wrapped in plastic wrap) and 805 (wrapped in aluminum foil) indicate the start of freezing at the sensor, and 806 (wrapped in plastic wrap) and 807 (wrapped in aluminum foil) indicate the end of freezing for the sample. Ice has good thermal conductivity, so for small samples, if latent heat is released anywhere, it will affect the entire sample through thermal conduction or infrared radiation, and this can be read from the cooling curve. When latent heat release completely ceases, an inflection point appears in the cooling curve, followed by a rapid temperature drop. For both samples, the sensor was inserted at the same center of the konjac. Unlike water, water and ice do not move in konjac due to convection or differences in density between ice and water. Therefore, the bottom was insulated, and freezing began from the top and sides. Since the sensor position and the start and end of freezing are considered to be the same, the latent heat release time, freezing start time, and solidification time are meaningful, making comparisons possible. The experimental results of the drip rate of the konjac used as the sample are shown in Table 3A, the cooling curve measured by a sensor inserted into the center of the konjac is shown in Figure 8, and the results are also shown in Table 3B.

[0087] In Table 3B, aluminum foil packaging has a higher thermal conductivity than plastic wrap packaging, so the residence time in the maximum ice crystal formation zone for aluminum foil packaging should be shorter than that for plastic wrap packaging, but in reality, the residence time for aluminum foil packaging is longer. This is because the latent heat release time for aluminum foil packaging is extended. This is presumably because the sample emits infrared rays when releasing latent heat, and the aluminum foil reflects these infrared rays back to the sample surface and absorbs them. The results in Table 3A were obtained by measuring the sample weight. Table 3B is a table that combines the drip rates in Table 3A with the analysis results of the cooling curve.

[0088] Although aluminum foil packaging has a longer residence time in the maximum ice crystal formation zone than plastic wrap packaging, the drip rate is smaller with aluminum foil packaging. This suggests that the previously held theory is incorrect. In other words, it strongly suggests that the quality of freezing in slow freezing is determined not by the residence time in the maximum ice crystal formation zone, but by the solidification time. The mechanism behind this is discussed above.

[0089]

[0090]

[0091] [Experiment 3] Next, cylindrical samples of flat konjac were used to test the drip rate under various freezing conditions. The amount of drip was measured for pre-cooled and non-pre-cooled samples, aluminum foil and plastic wrap, and samples placed on a rack and directly on a metal surface, and the amount of drip was compared relative to the weight before freezing.

[0092] The results are shown in Table 4. Pre-cooling involved one day in a 0°C refrigerator, and freezing involved storing the samples in a commercial freezer at -25°C for one day. When using a rack for plastic wrap packaging, pre-cooling the samples resulted in 1% less dripping compared to not pre-cooling. When using a rack for aluminum foil packaging, pre-cooling the samples resulted in 4% less dripping compared to not pre-cooling. When the samples were placed in an aluminum hotel pan for metal-to-metal contact, the drip rate was the same for both aluminum foil packaging and plastic wrap packaging, regardless of whether the samples were pre-cooled or not.

[0093] It was found that food that was pre-cooled to near freezing point all the way to the core and then frozen had slightly less dripping than food that was not pre-cooled. Notably, food that was cooled to freezing point all the way to the core, wrapped in aluminum foil, and frozen on a rack had significantly less dripping. This suggests that pre-cooling at around 0°C caused supercooling, resulting in the formation of more ice nuclei in the food than would occur in a saturated state. Furthermore, it strongly suggests that the aluminum foil reflects infrared rays, extending the time for the food surface to release latent heat, causing the formation of more ice nuclei in the food.

[0094]

[0095]

[0096]

[0097] In Table 5, konjac samples were pre-cooled at 0°C for 12 hours and then frozen in a -20°C freezer for 12 hours. The sample number indicates the konjac number, with A representing the irradiated group and B representing the unirradiated group. For the infrared irradiation group, a hot pack with a surface temperature of 60°C, heated by the heat of oxidation of pure iron, was placed 40 cm above the sample and irradiated with infrared rays. The irradiated group had a slightly higher drip rate than the non-irradiated group, even though the sample was the same size. This is thought to be due to the infrared rays hitting the sample surface, raising the surface temperature, or because infrared irradiation continued after freezing had begun, lengthening the time from the start of freezing to completion.

[0098] In Table 6, konjac samples were pre-cooled at 0.5°C for 12 hours and then placed in a freezer at -20°C for 12 hours to freeze. The samples were frozen by placing an infrared irradiator 40 cm above the sample, which had an electric heater placed in an aluminum box with an anodized surface and was controlled to turn "ON" when the surface temperature reached 20°C and "OFF" when the surface temperature reached 50°C, and an anodized aluminum reflector was also placed 10 cm below the sample, irradiating the sample with the infrared irradiator.

[0099] In Tables 5 and 6, no effect of infrared irradiation was observed. This is thought to be because artificial infrared irradiation is difficult to control, and it is not possible to irradiate the sample with infrared at an appropriate wavelength and intensity only during the time when latent heat is released, as is the case with aluminum foil. However, if the walls, ceiling, and floor are made of infrared-reflecting material, the infrared rays emitted by the frozen object when releasing latent heat are simply reflected back. Since infrared intensity is inversely proportional to the square of the distance, it has the strongest effect on objects closest to the reflective material, thereby achieving the same effect as reflective packaging.

[0100] [Experiment 5] Two sets of molded konjac were placed in resealable storage bags made of aluminum foil and polyethylene laminate film. One set was stored in the bag at room temperature, resealed, and frozen (hereafter referred to as "unslit"). The other set was cut with scissors in six places, three on each side, and then resealed and frozen at room temperature (hereafter referred to as "slit"). After freezing, the bags were removed and compared for drip rate using a drip measurement method. As shown in Table 7, the results showed that the slit set had a 2.2% lower drip rate than the unslit set. This is thought to be because air containing a large amount of room-temperature water vapor was trapped inside the bag when the unslit set was sealed, causing a large amount of frost to form between the konjac and the bag wall, absorbing the latent infrared radiation generated by latent heat radiation. On the other hand, when the bag had a slit, the air that had been sealed inside the bag and contained a large amount of water vapor escaped through the slit when it was placed in the freezer, and instead the air from inside the freezer entered, which is thought to have suppressed frost formation and allowed the latent heat infrared reflection to reach the food sufficiently.

[0101]

[0102] [Embodiment 1] This will be explained with reference to Figs. 5, 6, 7, 9, and 10.

[0103] Figures 5 and 6 show an example of a freezer with a double-layered structure that cools the top and the back of the wall without installing a cooler inside the freezer, and show cross-sectional views of the double-layered wall. Figure 6 is a side cross-sectional view of the top of the double-layered freezer. Figure 6 is a side cross-sectional view of the side wall of the freezer.

[0104] First, with reference to Figures 5 and 6, the cooling means and interior structure of this embodiment will be described in detail. The interior wall panels (505, 601) surrounding the interior may be made of mirror-finished aluminum plates. Heat transfer pipes (504) are installed in close contact with the rear side of the interior wall panels, allowing low-temperature refrigerant to circulate from an external cooling device, thereby uniformly cooling the interior wall panels from the rear side. Heat insulation (502) made of rigid urethane foam or the like may be installed between the interior wall panels (505) and the exterior wall panels (501). Cooling of the interior is achieved by indirect cooling via the interior wall panels, without directly exposing the heat transfer pipes or the like to the interior space. This facilitates maintaining high humidity within the interior, preventing food from drying out or the formation of ice films on the surface. Furthermore, as shown in Figure 6, the interior wall panels may be formed with multiple openings connecting the interior space and the cooling gap, thereby reducing the temperature difference between the two spaces and preventing frost formation on the interior wall surfaces. Furthermore, a fan (503) or other air blowing means is installed in the interior space as needed to make the temperature inside the storage uniform and circulate air during defrosting.

[0105] Fig. 7 is a side cross-sectional view of a freezer with a frost sensor installed on the wall inside the freezer. Fig. 10 shows a wire shelf with a reflector installed inside the freezer. Fig. 9 is an explanatory plan view of a freezer with a low-temperature front compartment, viewed from above.

[0106] As shown in FIG. 9 , the freezer (801) of this embodiment is equipped with a front chamber (808) with a double-door structure consisting of an inner door (804) and an outer door (807). A dehumidifier (805) and a temperature / humidity sensor (806) are installed within the front chamber (808), enabling the air within the front chamber to be maintained at a low temperature (e.g., approximately -5°C) and low humidity (e.g., approximately 30% relative humidity). This reduces the temperature and humidity of the outside air flowing into the freezer when the door is opened and closed, minimizing the formation of temporary frost on the interior walls. As a result, a stable low-humidity environment within the freezer can be maintained without impairing the latent heat infrared reflective performance.

[0107] When applied to low-temperature, high-humidity freezers or storage units where the walls are cooled without a cooling unit inside the freezer, the interior wall surface in Figure 9 is made of mirror-finished pure aluminum plate, which highly reflects latent heat infrared rays. When the temperature difference between the inside and outside air temperatures is large, especially in Japan's hot and humid summers, outside air enters the freezer when items are being loaded and unloaded, causing temporary frost formation on the walls. Frosted walls absorb latent heat infrared rays, reducing their reflectance to nearly 0%. Therefore, as mentioned above, to shorten the frost formation time, it is recommended to install a front compartment and install a dehumidifier in the front compartment as shown in Table 8 to lower the front compartment temperature to -5°C and humidity to around 30% rH. Reducing the temperature and humidity of outside air intrusion reduces the amount of frost that forms on the walls and ceiling, thereby shortening the frost formation time.

[0108] Furthermore, a frost sensor (see FIG. 7) may be provided, which, upon detecting frost, sends a signal to the control unit to activate the defroster. The defroster may be, for example, a combination of a device that defrosts the wall surface by simultaneously running a fan (503) while flowing hot water through the heat transfer pipe (see FIG. 5). Defrosting the wall surface can maintain high humidity and ensure stable refrigeration quality. Furthermore, providing a communication hole in the wall surface (see FIG. 6) reduces the temperature difference between the gap space (cooling space) and the internal space, thereby suppressing frost formation on the inner wall surface. By flowing hot water through the heat transfer pipe only when the frost sensor detects frost, power consumption can be minimized without significantly reducing cooling efficiency. Furthermore, as shown in FIG. 7, the infrared radiation unit of the frost sensor may be an infrared irradiator that directly irradiates the inner wall surface or ceiling surface for defrosting. This allows frost on the wall surface to be quickly melted and evaporated, defrosting only when necessary, and constantly maintaining the high infrared reflectivity of the inner wall surface as a reflector.

[0109] Furthermore, by installing mesh shelves with reflectors inside the freezer as shown in Figure 10, the latent infrared heat emitted from the food can be reflected over the shortest distance and returned to the food, achieving high-quality freezing.

[0110] Figure 10 shows a wire rack supporting the frozen food, with an infrared reflector positioned opposite the food. The reflector efficiently reflects latent infrared radiation (wavelengths 9-15 μm) emitted from the food and returns it to the food's surface. To maximize the infrared reflection effect, it is desirable to maintain a short distance between the reflector and the food. The reflector is preferably designed with a variable-position fixture (position adjustment mechanism) that allows it to be positioned directly below the food within a range of several millimeters to several centimeters. The wire rack and the reflector have significantly different material properties and functions. The wire rack must be designed to support the food while allowing cold air and infrared radiation to pass through, making a highly breathable metal or resin material suitable. On the other hand, the reflector is preferably made of a mirror-finished metal material with an infrared reflectivity of 80% or higher. Therefore, by separating the two components, each component can be independently optimized, enabling flexible design based on food size and placement requirements. Furthermore, by making the reflector a separate structure, it becomes easier to combine it with a heating means or a blower mechanism to prevent frost formation, which contributes to maintaining the reflecting performance and improving maintainability. As a result, it is possible to achieve highly efficient and stable freezing quality.

[0111] In the freezing method of this embodiment, infrared rays (latent heat infrared rays) associated with latent heat radiation from the food are efficiently returned to the food surface, thereby extending the time required for latent heat release within the food and allowing numerous ice nuclei to form within the food during that time. The greater the number of ice nuclei, the more simultaneously ice crystal growth that begins after latent heat release occurs at numerous points within the food, shortening the freezing time required for all ice crystals to grow. The shorter the freezing time and the smaller the ice crystal size, reducing cell membrane destruction. Furthermore, by initiating freezing from the inside, the unfrozen surface layer absorbs the internal freezing expansion, reducing cracking and damage to the surface. This makes it possible to achieve high-quality freezing results, with reduced dripping after thawing. In other words, the configuration of the present invention reliably improves the freezing quality of food.

[0112] The wavelength of maximum spectral radiant energy (hereinafter "λmax (unit: μm)") at the absolute temperature of a black body (hereinafter "K") has the relationship of the following formula 1.

[0113] [Formula 1] λmax = 2,897 / K

[0114] The wavelengths of latent heat infrared radiation emitted during the food freezing process are primarily distributed in the 9-15 μm range, with a peak intensity at approximately 110 μm (±1 μm). Because water and ice have a high absorption rate in this wavelength range, it is desirable for the surface of the reflector to be given a mirror finish that efficiently reflects long-wavelength infrared radiation. In other words, the reflector of the present invention serves to return long-wavelength infrared radiation back to the food, thereby enabling the maximum amount of radiant energy emitted during latent heat release to be resupplied to the food surface.

[0115]

[0116] Food freezing methods can be broadly divided into quick freezing and slow freezing. With quick freezing, the core temperature of the food passes through the "maximum ice crystal formation zone" between freezing point (approximately 0°C) and -5°C in a short time (within 20 minutes), making it easier for fine ice crystals to form and reducing cell destruction and dripping. On the other hand, slow freezing, which is done in a typical freezer, takes 30 minutes to several hours to pass through this temperature zone, which has the disadvantage of causing the ice crystals to grow larger and increasing dripping after thawing.

[0117] Although good quality can be achieved with slow freezing by freezing through a supercooled state, it has been difficult to reliably reproduce supercooling in all foods and achieve supercooling with 100% accuracy. To address this issue, the present invention employs a structure that uses a reflector to reflect long-wavelength infrared rays (latent heat infrared rays) emitted when food releases latent heat back to the surface of the food, thereby promoting the formation of ice crystal nuclei and successfully shortening the solidification time. This allows for stable, high-quality freezing even with slow freezing.

[0118] Furthermore, in order to maintain infrared reflectivity, a means for preventing and removing frost from the reflector surface is also provided. In this invention, a heating means is provided on the reflector to melt the frost, and the interior walls of the freezer are made double-walled, keeping the temperature difference with the cooling space small to suppress frost formation. These configurations provide a new freezing technology that achieves high-quality freezing from both ice crystal control and a reflective environment, even in slow freezing, which was previously unstable.

[0119] [Quantitative Measurement Method for Thawing Quality] We have developed a method to quantitatively determine the quality of thawing conditions. When thawing cellular foods slowly at low temperatures, the extracellular fluid in contact with the outside thaws first, followed by the intracellular fluid. However, because the osmotic pressure inside the cells is higher than that of the extracellular fluid, when the intracellular fluid thaws, it deprives the extracellular fluid of its latent heat of fusion, causing it to refreeze. Furthermore, the outer cells thaw first, and then, as the inner cells thaw, they deprive the outer cells of their latent heat, causing them to refreeze. This cycle is repeated throughout the food during thawing, causing ice crystals to grow and increase in size during refreezing, further damaging cell membranes damaged by freezing expansion from both the inside and outside. However, once thawing is complete, some of the adhesive proteins that hold the cells together appear to recover and repair the damage. The cell membrane is also partially repaired, albeit imperfectly, thereby suppressing drip leakage. If these processes are correct, then the amount of drip from konjac cannot be used to evaluate the quality of thawing, and it is meaningless unless actual samples consisting of cells are used. We actually measured the drip rate of konjac thawed in warm water and at near-freezing temperatures, but found no significant difference between the thawing conditions. Furthermore, for samples consisting of cells, the amount of drip and hardness vary significantly depending on the cutting method, so only organs without slits are meaningful. Therefore, chicken breast meat was used as the sample because of its moderate size. Chicken breast meat has a low drip rate, making it impossible to evaluate by drip rate. Therefore, we used a hardness meter to compare the hardness before and after freezing. Because hardness varies depending on the sample's temperature and past temperature history, we first refrigerated and cooled it at the same temperature, then returned it to room temperature, where it is most stable. We then measured the front side before freezing and the back side of the same chicken breast after thawing, subtracting the pre-freezing measurement from the post-thaw measurement to compare the difference in temperature. The protocol is shown below.

[0120] 1. Loosely wrap the chicken sample (hereinafter referred to as "sample") in polyethylene wrap film from front to back and side to side, leaving some slack. The measurement surface should be covered in a single layer of wrap. (Most cheap wraps other than Saran Wrap and Krewrap are made of polyethylene.) 2. Place the GS-621 weight (1 kg) on ​​the sample and stretch it evenly. 3. Place the wrapped sample in the refrigerator and store for at least one hour to stabilize the temperature. 4. Remove from the refrigerator and measure five locations on the thickest part using a Teclock durometer GS-754G (OP). Avoid measuring the same location, and measure five locations so that the entire surface is stretched evenly (so that deformation due to measurement is consistent). Use the maximum lowering speed of the GS-621. Handle the sample measured in 5.4 with care to minimize deformation as much as possible. 6. Place the wrapped sample on a metal hotel pan that has been pre-cooled in a freezer at -20°C or below, and store in the same freezer for one day to completely freeze. Prevent supercooling by placing the sample in contact with pre-cooled metal and then freezing in the freezer. 7. Thaw completely under each thawing condition. Ensure that the moisture in the sample does not evaporate during thawing. 8. Store the wrapped sample in the refrigerator for at least one hour to cool. 9. After removing the sample from the refrigerator, leave it at room temperature for one hour. 10. Measure five locations on the back of the surface measured in 4, avoiding any recesses, in the thickest part. Use the maximum descent speed of the stand. Exclude the maximum and minimum values ​​of the measured values ​​(Op) and convert the intermediate value to a Type A point (Ap) using the following conversion formula, then average the three values ​​and round off any decimal points to evaluate as an integer.

[0121] [Conversion formula] 55<Op<90 AP=0.064・Op 2 +1.9・Оp-68.914 30<Оp<55 Ap=0.0245・Оp 2 -1.539・Оp+26.03 10<Оp<30 AP=0.003・ОP 2 -0.0254・Op+0.0769

[0122]

[0123] Table 9 compares the difference in hardness between two chicken fillet samples, which were wrapped in aluminum foil, frozen, and thawed at room temperature. One was thawed in the aluminum foil, and the other was thawed after removing the aluminum foil and wrapping in polyethylene film. Figure 18 is a graph showing the thawing time of konjac wrapped in aluminum foil and polyethylene film. Table 5 suggests that the konjac wrapped in aluminum foil took longer to thaw, resulting in poorer thawing quality.

[0124] Figure 18 is a comparative graph showing the difference in thawing time between polyethylene film packaging and aluminum foil packaging. This graph confirms that aluminum foil packaging blocks infrared absorption, prolonging the thawing time, during which ice crystals re-grow and the amount of dripping tends to increase. On the other hand, polyethylene film packaging allows infrared rays from the outside to pass through, enabling rapid thawing, resulting in good quality after thawing. The present invention achieves high quality in both freezing and thawing by using a dual structure that switches the reflective environment between freezing and thawing.

[0125] [Embodiment 1] This embodiment will be described with reference to Figs.

[0126] Figure 13 is a side cross-sectional view of one embodiment of the freezing bag of the present invention. This freezing bag has a two-layer structure, with an aluminum-vapor-deposited polyethylene terephthalate film (1101) as the outer layer and a low-density polyethylene (LDPE) film (1102) laminated to the inside. The outer layer has a high reflectivity for long-wavelength infrared radiation (9-15 μm) and functions to return latent infrared radiation to the food surface. Meanwhile, the inner layer is flexible and sealable to ensure adhesion and hygiene, assuming contact with food. Furthermore, a protruding convex portion (1103) is formed on one side of the bag's exterior. This convex portion creates a space between the bag bottom and the support shelf during freezing, allowing refrigerated air to circulate and envelop the entire bag for cooling.

[0127] Figure 14 shows the top view of the freezing bag shown in Figure 13, which features an air vent (2002) and a stopper (2001) for efficiently venting the air inside the bag. A commercially available vacuum pump, such as a wine vacuum pump, can be attached to the air vent, allowing for easy removal of the humid air inside the bag after food is placed inside. This prevents frost from forming due to the high humidity air trapped inside the bag during freezing and ensures an environment where latent heat infrared rays can reach the surface of the food.

[0128] Figure 15 is an explanatory diagram showing another form of air vent structure. In this form, a simple zipper (2004) with a check valve structure is combined with an air vent hole provided near the bag opening (2003). This structure allows air to be released when suction is applied, but prevents outside air from re-entering after the bag is opened. This suppresses the intrusion of external water vapor when food packed in a bag at room temperature freezes, preventing the formation of frost and the resulting loss of latent heat infrared radiation.

[0129] This embodiment is used in food freezing bags, vacuum packing bags, and food freezing boxes made with aluminum-coated paper. By providing a convex portion on one side, as shown in Table 4, when pre-cooling food, if the food is frozen on a plastic or wooden shelf, the convex portion creates a gap between the plastic or wooden board, allowing the food to be enveloped in cooled air, synergistically adding a supercooling effect to the latent heat infrared reflection effect. Furthermore, if the food is not pre-cooled and a metal plate that has been pre-cooled at a low temperature is present, contact freezing can be performed with the aluminum-coated side without the convex portion facing down, thereby accelerating the freezing rate and achieving high-quality freezing.

[0130] Figure 16 is a cross-sectional view of another embodiment of a freezing bag, in which a water-absorbing layer (not shown) is sandwiched between the food and the aluminum-coated surface. The water-absorbing layer is impregnated with water or a water-absorbent polymer, and during freezing, the temperature inside the bag is maintained at around 0°C due to the release of latent heat from the water layer. The pre-cooling effect of this water layer maintains a uniform temperature at the core of the food at the start of freezing, promoting the formation of a supercooled state and increasing the ice nucleus density. Furthermore, by adding salt or alcohol to the water-absorbing layer, the cooling profile can be adjusted to accommodate the freezing characteristics of various foods.

[0131] In addition, as shown in Figure 16, by absorbing water into a water-absorbent polymer and placing it between the aluminum-coated surface and the food, while the water in the water-absorbing layer releases latent heat during freezing, the temperature remains constant at the freezing temperature of around 0°C. This means that the temperature inside the bag is pre-cooled to around 0°C, and the food is pre-cooled to the core and frozen, improving the quality of freezing as shown in Table 4, and enabling high-quality freezing. The freezing point can also be lowered by dissolving alcohol or salts in water. The freezing point can also be adjusted by changing the polymer composition.

[0132] Figure 17 shows a top view of a double-bag freezer bag according to the present invention. The outer bag (2006) is made of a reflective aluminum vapor deposition material, and a separate polyethylene inner bag (2005) is placed inside. The opening of the inner bag is equipped with a zipper (2007), allowing the bag to be sealed and degassed after the frozen item is placed inside. During freezing, the entire outer bag reflects latent infrared rays, and during thawing, only the inner bag is removed and thawed in a mild infrared environment, greatly improving thawing quality.

[0133] 101 Starting point 102 Starting point of latent heat release from anodized aluminum 103 Starting point of latent heat release from aluminum 104 Starting point of freezing from anodized aluminum 105 Starting point of freezing from aluminum 106 Completion point of freezing from anodized aluminum 107 Completion point of freezing from aluminum 201 Upper test plate 202 Stainless steel container 203 Water 204 Resin spacer 205 Wooden spacer 206 Lower test plate 302 Ice surface 303 Ice 402 Ice surface 403 Ice 501 Outer wall panel 502 Heat insulating material 503 Fan 504 Heat medium piping 505 Inner wall panel 601 Inner wall panel 801 Freezer 802 Inner wall surface 803 Cooling device 804 Inner door 805 Dehumidifier 806 Temperature and humidity sensor 807 Outer door 808 Front room

Claims

1. A freezer comprising: a container for storing water-containing organic matter; a cooling device for directly or indirectly cooling the interior of the container; and a reflector that reflects at least 98% of long-wavelength infrared rays emitted from the water-containing organic matter when frozen toward the water-containing organic matter, the reflector being provided on the inner wall, ceiling, and floor surfaces surrounding the water-containing organic matter.

2. The freezer according to claim 1, wherein the anti-frost device comprises a heating device, a blower device, or a dehumidifier.

3. The freezer according to claim 1, wherein the surface of the reflector facing the water-containing organic matter is a mirror surface.

4. The freezer according to claim 1, wherein the walls or top of the container have a double structure with a gap space therebetween, and the cooling device indirectly cools the inside of the container by cooling the gap space.

5. The freezer according to claim 1, wherein the container has a refrigerant pipe on the back side of the wall or top surface, and the cooling device indirectly cools the inside of the container by passing a refrigerant through the refrigerant pipe.

6. The freezer according to claim 1, wherein the anti-frost device includes a heating device that heats the reflector by irradiating it with infrared rays.

7. The freezer according to claim 1, wherein the walls or top of the container have a double structure with a gap space therebetween, and the anti-frost device includes a heating device that heats the gap space.

8. The freezer according to claim 1, wherein the container has a refrigerant pipe on the back surface of the wall or top surface, and the anti-frost device includes a heating device that passes a heat medium at a temperature higher than the temperature inside the freezer through the refrigerant pipe.

9. A freezer as claimed in claim 1, wherein the walls or top of the container have a double structure with a gap space therebetween, and the walls or top have an opening that connects the gap space to the interior of the freezer.

10. The freezer according to claim 1, wherein the operation of the anti-frost device is controlled according to whether the door of the freezer is open or closed.

11. The freezer according to claim 1, further comprising a front chamber connecting the door of the freezer to the container, and the anti-frost device dehumidifies the air in the front chamber.

12. The freezer according to claim 1, comprising: a wire shelf for supporting the water-containing organic matter within the container; and a position adjustment mechanism for varying the height of the reflector relative to the water-containing organic matter placed on the wire shelf.

13. The freezer according to claim 1, wherein the reflector reflects 98% or more of infrared light with a wavelength of 9 to 11 μm, and the reflector is provided on the walls, top, and floor of the container, as well as on at least a portion of the front or back surfaces of shelves within the container.

14. A reflector used when freezing on a conveyor belt, in which a latent heat infrared reflective material is placed in contact with or near a part of the food surface, reflecting the latent heat infrared radiation emitted by the food during freezing and returning it to the food surface.

15. The reflector according to claim 14, which is used in a freezing method in which food is frozen while moving on a belt conveyor, and in which a latent heat infrared reflective material is provided on the surface of the belt conveyor that comes into contact with the food, or a reflective material is vapor-deposited or applied.

16. A package or container for freezing that contains a water-containing organic substance and is intended for freezing an object that is damaged by the expansion of water when frozen, characterized in that it comprises a reflective layer disposed so as to face at least the water-containing organic substance, and a water-containing layer that contains water on the inner surface of at least one of the packages or containers that faces the food.

17. A package or container for freezing according to claim 16, characterized in that the water-containing layer contains a freezing point depressant solute that causes the freezing point to be below 0°C.

18. A freezer package or container for freezing an object that contains a water-containing organic substance and that would be damaged by the freezing expansion of water when frozen, the package or container having: a reflective material layer arranged so as to face at least the water-containing organic substance; a convex portion provided on at least one surface of the package or container; and a degassing means, wherein the reflective material layer reflects latent heat infrared rays, which are infrared rays in the wavelength range of the latent heat radiation of water, to the surface of the water-containing organic substance when the water contained in the water-containing organic substance releases latent heat.

19. The freezer package or container of claim 18, wherein the latent heat infrared radiation comprises a wavelength range of 9 μm to 15 μm.

20. The freezer package or container of claim 18, wherein the surface of the reflector facing the frozen product is a mirror surface.

21. The freezer package or container of claim 18, further comprising a water-containing layer on the food side of the reflective layer.

22. A package or container for freezing as described in claim 18, comprising: an outer body having the reflective material layer; and an inner body made of a resin film placed inside the outer body, wherein the item to be frozen is contained in the inner body.

23. The freezer package or container according to claim 18, wherein the reflective material layer has a vent that allows ventilation to the outside.

24. The freezer package or container of claim 18, further comprising a resin layer on the inside of the reflective material layer.

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