Thawing method using latent heat infrared irradiation and thawing device therefor

Abstract

To provide the best thawing method for frozen foods.SOLUTION: A thawing method comprising thawing a frozen product containing cells while irradiating the frozen product with long-wavelength infrared rays in an environment at 0 to 10 °C.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a technology for thawing a water-containing object by irradiating it with latent heat radiation. [Background technology]

[0002] Previously, heat transfer around room temperature was mainly due to fluid convection and thermal conduction through contact, with a small proportion of heat transfer due to radiation, and since radiant energy is proportional to the fourth power of the surface temperature of the radiator in the case of a black body, it was thought that infrared radiation was not very effective unless the surface temperature of the radiator exceeded several hundred degrees Celsius. Furthermore, it was thought that infrared radiation had almost no effect on the heat dissipation or absorption effects at low temperatures near the freezing point of water or food.

[0003] Patent Document 1 discloses a thawing cabinet equipped with a carbon far-infrared emitting material. Patent Document 2 discloses sliced ​​butter made by pasting wafer paper on both sides of butter sliced ​​into plates. Patent Document 3 discloses a thawing cabinet with a temperature of 35°C to 45°C, which is composed of far-infrared emitting ceramics such as alumina and chromina and a reflector. Patent Document 4 discloses a vacuum thawing cooker equipped with a vacuum suction means and a far-infrared emitting means. Patent Document 5 discloses a thawing device consisting of an infrared emitting means and a reflector, in which 50% or more of the irradiated infrared rays have wavelengths of 5 μm or more. Patent Document 6 discloses a technology in which a heater is installed inside a radiator such as aluminum oxide, and frozen foods are thawed on the radiator. Patent Document 7 discloses a freezer / thawing cabinet that thaws using an aluminum plate and heater. Patent Document 8 discloses a freezer / thawing cabinet equipped with a mat-shaped far-infrared radiating heater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 06-050493 [Patent Document 2] Japanese Patent Application Publication No. 64-085039 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-034276 [Patent Document 4] Japanese Patent Application Publication No. 01-252258 [Patent Document 5] Japanese Patent Application Publication No. 56-138594 [Patent Document 6] Japanese Utility Model Application Publication No. 06-165661 [Patent Document 7] Japanese Patent Application Laid-Open No. 2003-028563 [Patent Document 8] Japanese Patent Publication No. 2022-136067 Summary of the Invention [Problem to be solved by the invention]

[0005] 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. Food, especially fresh foods, have a high moisture content, so the conventional theory for slow freezing was that if the food temperature remained in the maximum ice crystal formation temperature range of -5°C from the freezing point of the food for a long time, ice nuclei would gradually combine and the ice crystals would grow in size, destroying cell membranes and worsening the quality of the freezing.

[0006] As will be described in more detail later, the inventors discovered a method for quantifying freezing quality and found that, when comparing foods of the same shape, weight, and quality at the same ambient temperature (hereinafter "cabinet temperature"), with the same air velocity, thermal conductivity, and contact area of ​​the contacting object, the longer the time from the start of latent heat release to complete freezing (hereinafter "required freezing time"), the less dripping occurs after thawing. The conventional theory is that when food is frozen at a cabin temperature between 0°C and -5°C, which is the maximum temperature range for ice crystal formation, the greater the amount of dripping occurs after thawing, which is thought to be the accepted theory. However, in general freezing of foods, the cabin temperature is kept below -18°C, and food is cooled solely by the air inside the cabin, such as by placing a rack on top. Conversely, extending the required freezing time may extend the latent heat release time, forming more ice nuclei in the food, shortening the time from the start of freezing (when the ice nuclei begin to combine after latent heat release) to the end of freezing (hereinafter "solidification time"), thereby improving freezing quality.

[0007] On the other hand, when thawing foods made of cellular tissues, such as meat and fish, the cell membranes and intercellular adhesive proteins damaged by the volume expansion of water into ice crystals during freezing undergo a process of partial recovery during thawing. Furthermore, because tissues are composed of regions with different osmotic pressures, the once-thawed, low-osmotic pressure outer regions absorb latent heat from the low-osmotic pressure outer regions as heat is transferred to the inside, causing the high-osmotic pressure inner regions to thaw. Repeated cycles of this process result in the growth of ice crystals, damaging cells. This phenomenon is more pronounced in foods made of relatively high water content and higher osmotic pressure, especially when thawed more slowly. Furthermore, when slowly thawing cut foods, such as fillets, the drips that leak out of the food once thawed cannot be restored, and therefore do not contribute to the recovery of cell membranes and intercellular adhesive proteins, allowing the drips to be reabsorbed.

[0008] Food bags made of a laminate of thin metal film and resin film or a metal-deposited film have low gas permeability and are therefore used to prevent moisture, odor transfer, and oxidation. For this purpose, bags made of a laminate of aluminum foil and resin film are used as freezer bags for bread. Furthermore, Patent Document 1 discloses a thawing box installed inside a refrigerator, which consists of a metal inner box with good thermal conductivity, and a method of freezing an object by irradiating it with infrared rays from an electric heater. Patent Document 2 also discloses a technology for thawing food in a compartment at a temperature between a freezer and a refrigerator. As described in Patent Documents 1 and 2, irradiating the object to be thawed with infrared rays emitted by an electric heater, or as described in Patent Document 3, irradiating the object with far infrared rays using ceramic at the compartment temperature and providing a reflector to reflect the infrared rays, are common thawing methods.

[0009] However, radiation from electric heaters, which produce high surface temperatures, mainly emits short-wavelength infrared rays. Short-wavelength infrared rays from high-temperature radiators rapidly raise the temperature of the food being thawed, allowing for quick thawing. However, in the case of meat or fish fillets, a large amount of dripping occurs outside the food during thawing, preventing the full benefit of repairing damaged cell membranes. Furthermore, Patent Document 4 discloses a technology that can inhibit syneresis after thawing by adding Tremella fuciformis polysaccharides to beverages or processed foods. However, this technology is difficult to apply to meat or fish fillets. [Means for solving the problem]

[0010] The present invention is characterized in that frozen products containing cells (hereinafter simply referred to as "frozen products") are thawed by irradiating them with long-wavelength infrared light in an atmosphere with an internal temperature of 0°C to 10°C. By maintaining this temperature range, it is possible to prevent refreezing and maximize the maintenance of the quality of the thawed food. In this embodiment, a configuration may be adopted in which a temperature sensor is placed inside the refrigerator, and the cooling means and heating means are cooperatively controlled by a control device to precisely adjust the temperature within the range of 0 to 10°C depending on the type, size, and weight of the food.

[0011] When food is cooled to its freezing point, it begins 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 latent heat to surrounding objects and the cooling air in contact with the surface through three means: conduction, convection, and radiation. In the presence of solutes, the freezing point drops according to their molar concentration. During ice nucleation during latent heat release, only pure water forms ice crystals, 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, because radiant energy is proportional to the fourth power of the absolute temperature of the object's surface, it was intuitively thought to be negligible as a means of heat transfer at low temperatures.

[0012] However, at room temperature of 20°C (293K) and 0°C (273K), it is about 1.07 times, and even if this is raised to the fourth power, the energy is only 1.3 times. That is, even near 0°C, the radiation intensity and radiation energy do not change so much compared to room temperature and cannot be ignored as a heat transfer means. Also, like other heat transfer means, the absorption and radiation of infrared rays depend on the difference between the temperature inside the storage (hereinafter "Te") and the surface temperature of the object to be cooled (hereinafter "Ts"). When Te > Ts, absorption is dominant and it absorbs; when Te = Ts, radiation and absorption are in balance; when Te < Ts, radiation is dominant and it radiates. In the freezing process, the role of radiation is important along with the temperature of the object to be frozen and the magnitude of the temperature difference with the environment. During latent heat release, the condition Te > Ts always holds. The water in the object to be frozen releases latent heat to form ice crystal nuclei and radiates latent heat infrared rays to the surroundings. On the other hand, inside the food, the absorption peak wavelength of ice crystal nuclei at 0°C and the radiation peak wavelength of water are almost the same, and the ice crystal nuclei dissolve by absorbing latent heat infrared rays from the surroundings. The ice crystal nuclei formed on the surface layer are supplied to the inside, and the cycle of the ice crystal nuclei dissolving due to the absorption of their latent heat radiation is repeated. As long as the condition Te < Ts holds, ice crystal nuclei increase from the surface to the inside, and the latent heat inside is carried to the surface layer and radiated from the surface layer. When the ice crystal nuclei accumulate by the saturation amount, the ice crystal nuclei bind together as a whole, and the water that was liquid until then finishes releasing latent heat and starts freezing, and sequentially undergoes a phase transition to a solid starting from the freezing start site. It is considered that the higher the density of ice crystal nuclei in the object to be frozen, the faster the speed from the start of freezing to the end of freezing (hereinafter "solidification speed"). Conversely, if the solidification speed is slow, the time until the whole becomes solid is long, so the binding of ice crystal nuclei proceeds locally, and it is considered that the ice crystal size becomes large and cells are damaged. By reflecting the infrared rays of 9 - 20μm (hereinafter "latent heat infrared rays"), which are the main radiation wavelengths during latent heat release and absorption, externally and making the object to be frozen absorb them, the latent heat release time of the surface layer is extended. By forming an excessive amount of ice crystal nuclei in the object to be cooled compared to the saturation state, the solidification time is shortened, and the growth of the ice crystal size is suppressed, enabling high-quality freezing.

[0013] On the other hand, when thawing foods made of cellular tissues such as meat and fish, the cell membranes and intercellular adhesive proteins damaged by the volume expansion of water into ice crystals during freezing undergo a process of partial recovery during thawing. Furthermore, because tissues are composed of regions with different osmotic pressures, the outer, low-osmotic pressure region, once thawed, absorbs latent heat from the outer, low-osmotic pressure region as heat is transferred to the inside, causing the inner, high-osmotic pressure region to thaw, resulting in the low-osmotic pressure region refreezing. Repeated cycles of this process cause ice crystals to grow, damaging cells. This phenomenon is more pronounced in foods made of regions with a relatively high water content and higher osmotic pressure, when thawed more slowly.

[0014] The term "frozen product" is not limited as long as it contains cells, and examples include food such as meat, fish, and vegetables, fresh flowers, and cell tissue.

[0015] To utilize such latent infrared radiation, it is desirable to use an appropriate infrared reflector that efficiently reflects the infrared radiation back to the food surface. The reflector should preferably be made of a material that has a reflectance of 80% or more for infrared radiation with wavelengths of 8 to 15 μm, and particularly a high reflectance of 95% or more, and more preferably 98% or more, for wavelengths of 9 to 11 μm. [Table 1]

[0016] Actual reflectors include mirror-finished metal plates, metal foils, and metal-deposited films made of aluminum, silver, copper, or alloys of these. In particular, materials that exhibit high reflectivity in the 14.5 μm±2 μm wavelength range match the infrared absorption characteristics of unfrozen water and are advantageous in terms of re-absorption efficiency.

[0017] 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, at a few millimeters to a few centimeters, 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 a few percent of the infrared light with each reflection. Furthermore, with aluminum that is not mirror-finished, diffuse reflection can result in nearly 20% of the infrared light being absorbed with each reflection.

[0018] On the other hand, when reflective material is used on the walls of a defrosting chamber, the distance from the food is large, and the 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.

[0019] This invention is characterized by the use of a latent heat infrared radiation means that controls the surface temperature of the radiator to 20°C to 50°C by turning on and off high-temperature heating means such as an electric heater or halogen heater, or by controlling the voltage. The radiator irradiates the frozen product in a non-contact manner so that the radiator does not come into direct contact with the surface layer of the frozen product, and the latent heat infrared rays are absorbed by the surface layer of the food to thaw it. By keeping the radiator at a constant distance from the food and not in direct contact with it, local temperature increases on the food surface can be prevented, and quality deterioration can be suppressed. Furthermore, this non-contact method allows for gentle and uniform heat energy to be supplied to the entire food, achieving stable thawing quality.

[0020] Infrared rays with wavelengths between 8 and 15 μm are called long-wavelength infrared rays. This wavelength range is also the infrared wavelength used for the latent heat release and absorption of water and ice at 0°C. Therefore, irradiating the surface of the frozen object can extend the latent heat release during freezing. Furthermore, in this wavelength range, the blackbody's peak radiation temperature is around 20°C (room temperature). The peak radiation wavelength is inversely proportional to the radiator's surface temperature, and the radiant energy is proportional to the fourth power of the surface temperature. Because temperatures inside freezers are typically below -18°C, using short-wavelength infrared rays in the infrared absorption wavelength range of water and ice requires the radiator's surface temperature to be raised to nearly 400°C, which can significantly affect the temperature inside the freezer. Long-wavelength infrared radiation allows the use of low-temperature radiators, which is environmentally friendly and requires less electricity. Radiators made of rubber, which has high emissivity in this wavelength range, and ceramic or anodized aluminum, which is close to a blackbody, are desirable for the long-wavelength range. By controlling an electric or halogen heater to maintain the radiator's surface temperature between 20°C and 50°C, infrared radiation in a wavelength range roughly equivalent to latent heat infrared radiation can be emitted. When high osmotic pressure foods such as meat and fish are slowly thawed, the latent heat infrared rays emitted by the refreezing of low osmotic pressure parts are reflected by a reflecting means back to the surface of the food to prevent refreezing, and at the same time, by irradiating the food with infrared rays in the same wavelength band, it is possible to compensate for the latent heat infrared intensity attenuated by reflection, thereby ensuring high-quality thawing.

[0021] The long-wavelength infrared preferably includes a wavelength range of 9.8±2 μm. Because ice nuclei have a high absorption rate for long-wavelength infrared around 9.8 μm, it is preferable for thawing to involve absorbing infrared light with a wavelength of 9.8 μm. This wavelength range allows ice nuclei and unfrozen water in food to efficiently absorb latent heat, effectively suppressing refreezing and potentially reducing cell damage and dripping during thawing. Water also has a high absorption rate for long-wavelength infrared around 14.5 μm.

[0022] The heating means may be an electric heater, a halogen heater, or another heater that irradiates a radiator with short-wavelength infrared rays. Furthermore, if the internal temperature of the refrigerator exceeds 10°C due to heating of the radiator by the heating means, the refrigerator may further include a cooling means for lowering the internal temperature.

[0023] In addition, in this embodiment, a food recognition device such as a weight sensor or image recognition sensor may be installed inside the freezer to automatically detect the type, size, and weight of food, and a control system may be provided that adjusts the infrared radiation intensity and radiation time from the radiator in real time accordingly. This configuration makes it possible to automatically and quickly set optimal radiation conditions according to the characteristics of various foods, thereby achieving consistent thawing quality for foods.

[0024] Furthermore, this embodiment may be configured with a dehumidification system or dry air circulation mechanism to maintain low humidity inside the refrigerator. This configuration prevents condensation on the refrigerator walls and infrared-transmitting windows during thawing, and allows stable infrared transmission and reflection efficiency to be maintained over a long period of time, ensuring stable irradiation of latent heat infrared rays onto the food surface.

[0025] In the present invention, the thawing chamber has a window made of resin or infrared-transmitting glass that allows long-wavelength infrared rays emitted from a room-temperature environment to enter the chamber, and long-wavelength infrared rays from the external environment are allowed to enter the chamber as part of the long-wavelength infrared rays.

[0026] The radiation from objects in room temperature environments has high spectral radiance in the wavelength range of approximately 9 to 20 μm. This is also the wavelength range of latent heat infrared radiation, so if the radiation in the environment can be captured, the quality of freezing can be improved. Therefore, by installing an infrared intake window made of highly transparent polyethylene in this wavelength range, it is possible to compensate for the latent heat infrared reflection without consuming extra energy, thereby improving the quality of thawing. Low-density polyethylene film has an exceptional absorption of 30 to 40% in the long-wavelength infrared range at wavelengths of approximately 14 μm, but at other wavelengths it has nearly 100% transmittance.

[0027] The "room temperature environment" refers to the outside of the thawing cabinet. For example, even if the outside of the storage cabinet is not at room temperature in summer or winter, it is preferable to let in long-wavelength infrared rays from the external environment. Furthermore, the "window" is not limited to soft polyethylene, etc., as long as it has high transmittance for long-wavelength infrared rays. For example, it is preferable that the window have a transmittance of 90% or more in the wavelength range of 9.8±2 μm.

[0028] In the present invention, the irradiation means for irradiating the long-wavelength infrared rays uses a reflector made of aluminum or an aluminum alloy with an anodized reflective surface, and converts the short-wavelength infrared rays of an electric heater or halogen heater into long-wavelength infrared rays and irradiates the material to be thawed.

[0029] Anodized aluminum has a high emissivity among ceramics, and because the film thickness is very thin, the thermal conductivity of the metal base makes the reflector's thermal conductivity higher than other ceramics. By controlling the reflector temperature to around 50°C, the radiation from electric heaters and lamp-type halogen heaters that emit short-wavelength infrared rays is absorbed, and the anodized aluminum layer emits (reflects) long-wavelength infrared rays, enabling high-quality thawing.

[0030] The present invention is characterized in that an oblate is attached to the cut surface of the object to be frozen and then frozen, or an oblate is attached to the cut surface as a pretreatment for thawing and then thawed.

[0031] By applying a sheet-like oblate made by spreading hot water containing dissolved starch into a thin film and drying it to the cut surface of meat or fish, freezing it, and then thawing it, the starch's water absorption ability can be used to retain drips on the cut surface, suppressing drip leakage to the outside of the food and allowing cell membranes and intercellular adhesive proteins to recover during the thawing process, thereby improving the quality of thawing. Alternatively, an oblate can be applied to the cut surface when thawing frozen fillets of meat or fish.

[0032] In this invention, any food that retains its cellular shape at the time of freezing is acceptable. The purpose of thawing by latent heat infrared absorption is to improve the quality of thawing by suppressing the amount of dripping due to cell damage. Therefore, processed foods with destroyed cells, such as wheat flour, rice flour, and cornstarch, are not included. The cells or tissues may be living or dead.

[0033] As a further embodiment of the present invention, a thawing chamber can be provided, which has a thawing compartment in a low-temperature environment of -5°C to +5°C, with a portion of the wall surface absorbing infrared rays emitted from a room-temperature environment (room-temperature infrared rays). This temperature range corresponds to the chilled temperature range of a typical refrigerator and provides an environment that effectively promotes the regeneration of cell membranes and intercellular adhesion proteins while preventing microbial activity and protein degradation that can impair the freshness and quality of food during thawing. In this low-temperature environment, food surfaces are prone to repeated refreezing during thawing, so it is preferable to continuously supply infrared energy in an appropriate wavelength range to the food surface. However, installing a high-temperature radiator inside the chamber and directly irradiating infrared rays can cause an excessive temperature rise on the food surface, which can actually reduce the quality of the food. To solve this problem, the present invention employs a method of absorbing infrared rays emitted from a room-temperature environment (room-temperature infrared rays) into the chamber.

[0034] To capture room-temperature infrared rays, the present invention provides a transparent wall (transparent window) that transmits infrared rays on a portion of the wall of the thawing chamber (or thawing compartment). This transparent wall is preferably made of a material with particularly high infrared transmittance in the 9-15 μm wavelength range. Specifically, it is advantageous to use infrared-transparent glass or polyethylene resin. Special glass with high infrared transmittance, such as germanium-based, zinc selenide-based, or silicon-based glass, can be used as the infrared-transparent glass, achieving a high transmittance of 90% or more in the 9-15 μm band. Meanwhile, low-density polyethylene (LDPE) is particularly suitable as a polyethylene resin, as it has high infrared transmittance (approximately 90% or more) and is easy to process and cost-effective. By providing such a transparent wall on a portion of the wall facing the outside (room-temperature environment) of the thawing chamber, long-wavelength infrared rays naturally emitted from the external environment can be efficiently captured and irradiated onto the surface of food.

[0035] Furthermore, it is desirable that the walls, ceiling, and floor (hereinafter referred to as "peripheral surfaces") of the thawing chamber (or thawing compartment) other than the room-temperature infrared-transmitting walls reflect and re-irradiate the infrared rays that enter the chamber onto the food surface, thereby further increasing irradiation efficiency. For this reason, the present invention employs a configuration in which these peripheral surfaces are formed from a reflective material with extremely high infrared reflectivity. In particular, the reflective material used in the present invention must have a high reflectivity of 95% or more for infrared rays in the 9 to 15 μm wavelength band. Examples of such reflective materials include pure aluminum plates with a mirror-finished surface, aluminum plates with anodized aluminum, and aluminum alloy plates with similar surface treatments. These reflective materials efficiently and repeatedly reflect room-temperature infrared rays that enter the chamber, allowing them to be uniformly and efficiently irradiated onto the surface of the food inside, resulting in minimal energy loss and extremely good thawing quality.

[0036] As described above, in a low-temperature environment of -5°C to +5°C, the refrigerator employs a configuration in which external room-temperature infrared rays are captured by the transparent walls and then multiple reflections are performed by the reflective material inside the refrigerator, enabling latent heat infrared rays to be irradiated at a natural intensity onto the surface of food. This prevents refreezing of the surface of the food and ensures sufficient time for repair of cell membranes and intercellular adhesion proteins, significantly reducing drip leakage from thawed food. Furthermore, this configuration does not overheat the food surface compared to artificially irradiating it with excessive infrared rays, reliably preventing surface protein denaturation and quality degradation, thereby maintaining the original texture and freshness of food even after thawing.

[0037] It has been confirmed that when artificial infrared irradiation methods (e.g., irradiation from a heating pad or high-temperature heater) are used, the infrared intensity irradiated onto the food surface exceeds the latent heat infrared intensity naturally emitted by the frozen food, resulting in localized heating of the food surface and, in turn, increased dripping, which has the opposite effect. This phenomenon has been demonstrated in comparative experiments conducted by the inventors. On the other hand, with a method such as the present invention that captures infrared naturally emitted from a room temperature environment, the infrared irradiation intensity on the food surface is moderate, equal to or less than the latent heat infrared intensity emitted by the food itself, preventing localized overheating and maintaining excellent food quality. Thus, compared to other artificial irradiation methods, the configuration of the present invention achieves the technical effect of enabling high-quality thawing while maintaining the food surface temperature within an optimal range. [Effects of the Invention]

[0038] Migratory fish such as tuna have large amounts of ATP and creatine phosphate stored in their muscles. After thawing, calcium ions leak from the vesicles containing calcium ions inside the cells that were destroyed during freezing, causing thaw rigor. Rapid thawing, in particular, can result in a large amount of dripping, which can reduce the quality of the food. Because the melting point is the temperature at which ATP decomposes most rapidly, slow thawing at temperatures around 0°C minimizes the amount of ATP remaining. In particular, slow thawing can improve the quality of thawing by returning or irradiating latent heat infrared rays to the food being thawed, preventing the refreezing of low-osmotic pressure areas during thawing. [Brief explanation of the drawings]

[0039] [Figure 1] Graph showing experimental results for explaining the present invention [Figure 2] FIG. 1 is a cross-sectional side view illustrating an experimental method of the present invention. [Figure 3] FIG. 1 is a cross-sectional side view illustrating the results of an experiment to explain the present invention. [Figure 4] FIG. 1 is a cross-sectional side view illustrating the results of an experiment to explain the present invention. [Figure 5] Graph showing experimental results for explaining the present invention [Figure 6] FIG. 1 is a cross-sectional side view of a defrosting chamber according to an embodiment of the present invention; [Figure 7] 10 is a cross-sectional side view of another example of a thawing box according to the present embodiment; [Figure 8] Side cross-sectional view of the lid of the defrosting box [Figure 9] Graph showing experimental results for explaining the present invention [Figure 10] Illustration of a halogen lamp infrared irradiator DETAILED DESCRIPTION OF THE INVENTION

[0040] 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.

[0041] The effects of the present invention will be explained using Figures 1 to 10. First, various experimental results (Figures 1 to 5, Figure 9) for verifying the role of latent heat infrared rays in the freezing and thawing processes, as well as the experimental methods and schematic diagrams (Figures 2 to 4) will be shown, and the configuration of the thawing device (Figures 6 to 8, Figure 10) will be specifically explained based on these findings.

[0042] Below, we explain the experiments we conducted to verify the effects of latent heat infrared rays. Through these experiments, we were able to estimate the mechanism of this discovery. Furthermore, prior to these experiments, we developed a new drip measurement method and a quantitative measurement method for thawing quality, as it had previously been difficult to quantify the quality of freezing and thawing.

[0043] In the past, the inventor froze agar and thawed it in a low-G environment using a centrifuge and a drip filter to compare the drip weight, but this method required an old-fashioned centrifuge in which the sample storage bucket could be freely angled 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 the drips it releases and returning to its original state.

[0044] Therefore, konjac sheets (hereinafter "flat konjac") from the same manufacturer and on the same production date were cut into shapes and frozen, then thawed at room temperature in a thawing hotel pan on a rack, covered with plastic wrap, and the weight of the drips was measured to compare the drip rates. Konjac is easy to obtain and process, and there is 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 drips and return to its original shape. For comparisons, cutting multiple samples from a single flat konjac sheet minimizes quality variation. When screening different flat konjac, avoiding buyer's brands and using products with the name of the konjac specialty manufacturer and the expiration date can minimize variation in drip rates.

[0045] [Experiment 1] To understand how water actually freezes, 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 frozen in a stocker at -25°C, with disposable chopsticks placed on a wooden spacer (205) on the bottom, placed on a rack (hereafter referred to as "anodized aluminum"). At the same time, the same water was placed in the same stocker 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.

[0046] The apparatus shown in Figure 2 consists of a metal container (202) filled with 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 a 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 a clear evaluation of differences in cooling curves, freezing times, and freezing behavior due to differences in the conditions under which infrared radiation is reflected and absorbed by the water surface during latent heat release.

[0047] A thermocouple sensor was fixed near the center of the water in the stainless steel container. 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 (105, 104). The solidification time was defined as the time from when the water temperature at the sensor dropped below 0°C (hereafter 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 caused 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, and the downward slope became steeper, resulting in an inflection point on the curve. This point (107, 106) was defined as the freezing completion point. Table 1 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.

[0048] 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.

[0049] 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 re-absorbed 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. Also, 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, so Experiment 2 was carried out so that the freezing start and completion positions would be the same.

[0050] [Table 2]

[0051] [Experiment 2] The konjac samples were placed in the freezer compartment of a household refrigerator. The surface of the cut-out konjac was covered with vinylidene chloride resin wrapping film (hereinafter referred to as "wrapped"), and the surface of the konjac was covered with aluminum foil with the mirror side facing inward (the konjac side) (hereinafter referred to as "aluminum foil wrapped"), and frozen on an insulating sheet placed on the floor of the plastic freezer to reduce 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 one day. After thawing, they 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 -18°C to -20°C.

[0052] Figure 5 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 on the cooling curve. When latent heat release completely ceases, an inflection point appears on 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 density differences 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 for 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 5, and the results are also shown in Table 3B.

[0053] 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 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, which are reflected by the aluminum foil and returned to the sample surface for absorption. The results in Table 3A were obtained by measuring the sample weight. Table 3B is a table that combines the drip rates from Table 3A with the analysis results of the cooling curve.

[0054] 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.

[0055] [Table 3A]

[0056] [Table 3B]

[0057] [Experiment 3] Next, four of the cut-out konjac pieces were wrapped in plastic wrap and placed on a hotel pan in a -25°C freezer for one day. The next day, one piece was removed from the plastic wrap, rewrapped in aluminum foil, and placed on a freshly placed rack. The remaining three pieces were placed on the rack without removing the plastic wrap. The four pieces placed on the rack were left at room temperature for 15 hours to thaw, and then weighed to determine the drip rate. Table 4 shows the results of the drip rate measurements.

[0058] As shown in Table 4, the results showed that no difference was observed, and it was found that the quality of thawing cannot be evaluated by the drip rate of konjac. This is thought to be because damage and recovery due to thawing are caused by cellular structure, but konjac does not have a cellular structure. Therefore, we next attempted to quantify the quality of muscle, which is made up of cellular tissue.

[0059] [Table 4]

[0060] [Quantitative measurement method for thawing quality] Because slitting muscle and other organs can cause variability depending on the cutting method, chicken breast (hereafter referred to as "tenderloin") was used as a sample of unslit muscle. First, chicken breast was frozen under the same conditions and then thawed. A Teclock rubber durometer type OO GS754G was attached to a manual constant pressure load tester GS612 (hereafter referred to as the "stand") with automatic alignment correction and a descent speed adjuster, and hardness was measured at a 1 kg load and maximum descent speed. Chicken breast hardness was measured at three to a maximum of five locations. The maximum and minimum values ​​were excluded as outliers, and the intermediate value (hereafter referred to as "measurement points") was designated as Ep. The Type A durometer value (hereafter referred to as "points"), which has a linear relationship with stress, was designated as Ap. Op was converted to Ap using the following equation (1) for comparison. Although freezing and thawing would normally decrease hardness due to damage, it actually increased hardness. The reason for this is that there is no ATP remaining in the chicken fillet, so when a load is applied and measured once, the muscle stretches, and when the muscle is measured again around that point, the hardness increases. Furthermore, as the temperature of the chicken fillet rises, the hardness of the muscle decreases. Also, when slow-freezing and slow-thawing are performed under the same conditions, roughly one in four to five pieces exhibits high hardness. This is thought to be due to supercooling during slow freezing. Taking these factors into consideration, the hardness measurement protocol below has been established.

[0061] [Measurement comparison procedure] 1. Loosely wrap the chicken sample (hereinafter referred to as "sample") in polyethylene wrap film, leaving some slack on the front, back, left and right. 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 to stretch it evenly. 3. Place the wrapped sample in the refrigerator and store it for at least 1 hour to keep the temperature constant. 4. Remove from the refrigerator and measure the thickest part at five points using a Teclock durometer GS-754G (OP). Measure five points so as not to measure the same spot, and stretch almost the entire surface evenly (so that the deformation caused by the measurement is consistent). Lower the GS-621 at the maximum speed. Handle the sample measured in 5.4 with care to avoid 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 it in the same freezer for one day until it is completely frozen. By placing the sample in contact with the pre-cooled metal in the freezer, supercooling and freezing can be prevented. 7. Thaw completely under each thawing condition. Be careful not to let the moisture in the sample evaporate during thawing. 8. Store the wrapped sample in the refrigerator for at least 1 hour to cool. 9. After removing the materials from the refrigerator, let them sit at room temperature for 1 hour. Measure the backside of the surface measured in 10.4 at five locations on the thickest part, avoiding any recesses. Use the maximum speed to lower the stand. Exclude the maximum and minimum values ​​of the measured values ​​(Op), convert the intermediate value to a Type A point (Ap) using the following conversion formula, then average the three values, round off any decimal points, and evaluate as an integer.

[0062] [Conversion formula] 55<Op<90 AP=0.064·Op 2 +1.9 Op-68.914 30<Op<55 Ap=0.0245·Op 2 -1.539 Op+26.03 10<Op<30 AP=0.003·Op 2 -0.0254 Op+0.0769

[0063] [Experiment 4] In the comparative experiment, samples were thawed in a refrigerated thawing cabinet (hereafter referred to as "zero cabinet") with the interior temperature set to 0.5°C, in a refrigerator with an interior temperature of 8°C, and at room temperature of approximately 20°C, with the sample placed naked in an aluminum hotel pan with a rack placed on it and the pan covered three times with polyvinylidene chloride film, and in 40°C warm water, placed in a polyethylene bag, and then stored in an 8°C refrigerator for one hour, and then stored at room temperature for another hour, after which the hardness was measured. The thawing time for each was one day.

[0064] At first glance, these results suggest that ultra-slow thawing is the worst and that rapid thawing is better than slow thawing. However, when thawing in hot water at 40°C, the samples were wrapped in plastic wrap and placed in a film bag with high long-wavelength infrared transmittance. Although plastic wrap absorbs long-wavelength infrared, the long-wavelength infrared emitted by the surrounding hot water was sufficiently strong, and the wrap was also heated to 40°C to radiate. This may have led to the sample absorbing the infrared light, resulting in a smaller decrease in hardness compared to thawing in a refrigerator. When thawing at room temperature, the samples were wrapped in three layers of plastic wrap with high long-wavelength infrared radiation absorption and stored in a highly reflective aluminum pan, which likely reduced the influence of the surrounding long-wavelength infrared. Relatively rapid thawing at room temperature resulted in a smaller decrease in hardness than slow thawing in a refrigerator. The inventors hypothesize that when high-osmolality foods such as meat and fish are thawed slowly, the refreezing of low-osmolality areas during thawing causes ice crystal growth, resulting in a decrease in hardness. Furthermore, when the muscle is not cut as in this case, there is likely a process for repairing cell membranes destroyed by freezing. Intracellular fluid has a higher osmotic pressure than extracellular fluid and melts at a lower temperature. During thawing, the intracellular fluid first becomes completely liquefied, and while the extracellular fluid is in a semi-thawed state, the cell membrane, which is made up of phospholipids, regenerates on its own due to intermolecular forces resulting from its hydrophilic and hydrophobic polarity. If rapid thawing completely liquefies the inside and outside of the cells, water rapidly moves from the low-osmotic pressure extracellular fluid to the high-osmotic pressure intracellular fluid, preventing the regeneration of the cell membrane. In other words, slow thawing results in the refreezing of low-osmotic pressure areas, while rapid thawing results in poor thawing quality due to insufficient time for the cell membrane to regenerate. Therefore, it is thought that there may be an appropriate thawing speed between rapid and slow thawing.

[0065] [Table 5]

[0066] [Experiment 5] Table 6 shows the results of comparing chicken fillets that were frozen in polyethylene wrap and then wrapped in aluminum foil when thawed with chicken fillets that were left in the same wrap and thawed under different thawing conditions. Hot water > 8°C refrigerator > room temperature > 4°C refrigerator Compared to the results in Table 5, the results for room temperature and refrigerator are reversed. For slow thawing, the best thawing quality is around 8°C.

[0067] [Table 6]

[0068] Table 6 shows that thawing quality is better when thawing with polyethylene wrap than with aluminum foil, demonstrating that thawing quality improves when exposed to external room-temperature infrared light during thawing. Furthermore, Table 5 shows that thawing with long-wavelength infrared light controlled at 20°C to 50°C in a zero-temperature refrigerator, where slow thawing results in poor thawing quality, achieves thawing quality comparable to that achieved by thawing with warm water or immersion. This is because the maximum temperature of the infrared radiation source is 50°C, and the temperature of the irradiated surface of the frozen product after thawing does not exceed 50°C. 50°C is the boundary temperature at which proteins do not denature, so the quality after thawing can be maintained in a fresh state. Furthermore, thawing with air blown in a refrigerator near 0°C provides sufficient time for cells to repair damage after thawing, resulting in high-quality thawing. Furthermore, thawing with oblate-wrapped food resulted in no dripping, high hardness, and excellent thawing quality.

[0069] [Embodiment 1] 10 is a schematic diagram showing an example of a long-wavelength infrared irradiator used in the present invention, which uses a lamp-type halogen heater (1502) as a heat source and is made up of a reflector plate with an anodized aluminum reflective surface (1503) around it. The short-wavelength infrared irradiated from the halogen heater is absorbed and re-emitted by this reflector plate, becoming long-wavelength infrared with a wavelength of 8 to 15 μm (the wavelength range of latent heat infrared rays) and irradiating it onto the surface of the food.

[0070] Figure 6 is a side cross-sectional view showing an example of a thawing chamber equipped with the long-wavelength infrared irradiator of Figure 10 inside. The thawing chamber body is made of a thermally insulated box, and the interior walls (bottom, ceiling, and side walls) may be lined with an infrared-reflecting material such as an aluminum mirror plate (1501) to efficiently reflect and concentrate the long-wavelength infrared rays inside the chamber onto the food. The irradiation means (see Figure 10), which is an infrared generator, may be attached to the top of the chamber in a position that does not directly contact the food. In this case, the distance between the irradiation surface and the food may be kept as close as possible to prevent attenuation of the infrared intensity.

[0071] Figure 9 is a graph of experimental results showing the difference in defrosting time depending on the radiator material, comparing anodized aluminum (aluminum substrate), ceramics, PET resin, and other materials. While each material has a high emissivity of long-wavelength infrared rays at room temperature, anodized aluminum, with its metallic substrate and high thermal conductivity, reaches the desired temperature quickly and begins stable long-wavelength radiation, resulting in the shortest time for defrosting. On the other hand, materials with low thermal conductivity, even with high emissivity, require more time to reach the desired temperature, and tend to take longer to defrost. With the above configuration, long-wavelength infrared rays are irradiated onto food while maintaining a low-temperature environment of around 0 to 10°C inside the defrosting chamber, enabling slow, uniform defrosting throughout the food without a sudden rise in temperature or refreezing.

[0072] The surface temperature of the reflector can be controlled by turning the halogen heater on and off using a control circuit linked to a temperature sensor. For example, by controlling the halogen lamp on and off so that the reflector temperature is around 50°C, it is possible to absorb the short-wavelength infrared rays from the halogen heater and convert the reflected wave wavelength into a band containing a large amount of long-wavelength infrared components. The wavelength band of latent heat infrared rays is dominant between 20°C and 50°C. However, since the radiation intensity at 20°C is insufficient, setting the temperature around 50°C allows for sufficient intensity to compensate for the latent heat infrared rays. Within this temperature range, the radiant's peak wavelength matches the absorption characteristics of water and ice, and does not overheat the food surface, thereby offering the advantage of effectively compensating for latent heat infrared rays while safely thawing. The heat capacity and thermal conductivity of the reflector also affect thawing efficiency. Furthermore, since intensity is inversely proportional to the square of the distance, minimizing the distance between the radiator and the item to be thawed can achieve the desired effect. Furthermore, snow-melting mats are suitable for dedicated thawing cabinets, while radiators using anodized aluminum reflectors are suitable for dual-purpose refrigeration and thawing cabinets.

[0073] [Embodiment 2] This embodiment will be described with reference to Figures 7 and 8. Figure 7 is a side cross-sectional view of a freezer box according to a second embodiment, and has an infrared-transmitting window (top in the figure) in part of the top surface for taking in long-wavelength infrared rays from the external environment. The interior walls, ceiling, floor, and other peripheral surfaces of the box are all provided with mirror-finished pure aluminum material (high-reflectivity material), and may be configured to reflect 95% or more of infrared rays in the 9 to 15 μm wavelength band and re-radiate them to the food inside the freezer.

[0074] Figure 8 is a schematic side cross-sectional view showing the details of the infrared-transmitting window provided in the lid of the thawing box, and is an explanatory side cross-sectional view of the infrared-transmitting material in Figure 7. In this embodiment, a bubble cushioning material made of low-density polyethylene (LDPE) is used as the window material, and has a structure with many air bubbles (1301) and voids (1302) between the double film layers.

[0075] In this second embodiment, long-wavelength infrared radiation from the ambient temperature (e.g., 20-25°C) outside the freezer is introduced into the freezer through the infrared-transparent window shown in Figure 7 (detailed structure shown in Figure 8). This compensates for the latent heat infrared radiation emitted from food and attenuated inside the freezer during low-temperature thawing, ensuring sufficient infrared radiation to reach the food surface. This improves thawing quality without consuming additional power and is also energy-efficient. For example, when the outside temperature is 20-27°C, blackbody radiation in this temperature range has the highest spectral radiance in the wavelength range of 9-20 μm. In other words, all objects inside the freezer constantly emit infrared radiation in the same wavelength range as latent heat infrared radiation. By irradiating this ambient infrared radiation into the freezer from outside through the infrared-transparent window shown in Figure 7, the latent heat infrared radiation from the food attenuated inside the freezer can be compensated for. This embodiment saves energy because it does not require the use of a heat source such as an electric snow-melting mat inside the freezer.

[0076] The material shown in Figure 8 is bubble wrap made of LDPE film. However, in this configuration, condensation can form on the surface of the infrared-transmitting window due to the temperature difference between inside and outside the refrigerator. Condensation absorbs latent heat infrared rays, rendering the material ineffective. Therefore, the air bubbles (1301) and gaps (1302) are filled with dry air or dry nitrogen gas. By filling the air with a gas that does not contain water vapor, which causes condensation, while also providing insulation, condensation can be prevented. Furthermore, LDPE film transmits latent heat infrared rays at a high rate, extending the food's latent heat release time and enabling high-quality freezing. The infrared-transmitting window in Figure 7 can be made of polyethylene or a double-pane glass window with infrared-transmitting glass and a layer of dry air sandwiched between them. Using such glass improves aesthetics, strength, and durability. Furthermore, a defrosting drawer shelf can be installed between the refrigerator and freezer compartments of a household refrigerator. The front of the shelf is made of double-pane infrared-transmitting glass, and a reflector and rack are placed inside to enable high-quality defrosting (not shown).

[0077] As shown in Figure 8, dry air or nitrogen gas can be sealed within the LDPE multi-layer film to provide insulation and prevent condensation on the window surface due to temperature differences between the inside and outside of the refrigerator. If water droplets adhere to the window surface, long-wavelength infrared rays are absorbed and transmittance decreases. However, this structure fills the window with dry, moisture-free gas, preventing condensation and maintaining high infrared transmittance for long periods of time. Furthermore, the LDPE film used has nearly 100% transmittance for infrared rays in the 9-15 μm band, except for wavelengths around 14 μm. This allows latent heat infrared rays (radiation from room-temperature objects) from the outside environment to pass efficiently into the refrigerator, maintaining latent heat release from the surface of food while suppressing refreezing and promoting thawing. Furthermore, this infrared-transparent window is also effective in the food freezing process. Specifically, during freezing, the latent heat infrared radiation emitted from food does not escape to the outside environment through the window, but is instead reflected by the highly reflective walls of the refrigerator and absorbed back into the food. This extends the time for latent heat release, contributing to the increase and uniformity of ice crystal nuclei and suppressing ice crystal growth, achieving high-quality freezing. The infrared-transmitting window material is not limited to soft polyethylene film; it can also be made of a double-layered structure (with a layer of dry air sandwiched between them) of special glass that transmits long-wavelength infrared rays. In this case, the glass enhances the strength, durability, and aesthetic appeal of the window. For example, in a household refrigerator, a dedicated thawing drawer shelf in the intermediate temperature range between the freezer and refrigerator compartments could be installed, with the front of the shelf made of infrared-transmitting glass (double-paned window), and a reflector and a rack (mounting shelf) installed inside the refrigerator, making it easy to achieve high-quality thawing using this method even at home (not shown). [Industrial Applicability]

[0078] It can be used to thaw frozen products, including cells. [Explanation of symbols]

[0079] 101 Starting point 102 Anodized latent heat release starting point 103 Aluminum latent heat release starting point 104 Anodized aluminum freezing start point 105 Aluminum freezing starting point 106 Anodizing freeze completion point 107 Aluminum freezing completion point 201 Test Top Plate 202, 301, 401 Stainless steel containers 203, 303, 403 water 204 Resin spacer 205 Wooden Spacer 206 Test bottom plate 302, 402 water surface 801 Starting point 802 Wrap latent heat release starting point 803 Aluminum foil latent heat release starting point 804 Wrap freezing start point 805 Aluminum foil freezing starting point 806 Lap freeze completion point 807 Aluminum foil freezing completion point 1301 bubbles 1302 Gap 1303 PE film 1501 Mirror aluminum surface of shielding plate 1502 Lamp-type halogen heater 1503 Anodized aluminum reflective surface of reflector

Claims

1. A thawing method in which frozen products containing cells are thawed by irradiating them with long-wavelength infrared light in an environment of 0 to 10°C.

2. The long-wavelength infrared radiation includes a wavelength range of 9.8±2 μm. The thawing method according to claim 1.

3. The long-wavelength infrared rays are irradiated using a latent heat infrared radiating means having a radiator that radiates the long-wavelength infrared rays and a heating means that heats the radiator so that the surface temperature of the radiator reaches 20°C to 50°C, without bringing the radiator into contact with the frozen product. The thawing method according to claim 1.

4. the radiator is a reflector having an anodized aluminum or aluminum alloy on its reflective surface, The radiator converts the short-wavelength infrared rays irradiated by the heating means into the long-wavelength infrared rays and irradiates the long-wavelength infrared rays onto the frozen product. The thawing method according to claim 3.

5. The thawing is carried out in a thawing chamber, As part of the long-wavelength infrared rays, long-wavelength infrared rays from an external environment are incident into the thawing chamber. The thawing method according to claim 1.

6. The thawing is performed with an oblate attached to the cut surface of the frozen product. The thawing method according to claim 1.

7. A latent heat infrared radiation means is provided for thawing a frozen product containing cells by irradiating it with long wavelength infrared rays in an environment of 0 to 10°C. Thawing warehouse.

8. The long-wavelength infrared radiation includes a wavelength range of 9.8±2 μm. The thawing cabinet according to claim 7.

9. the latent heat infrared radiating means has a radiator that radiates the long-wavelength infrared rays and a heating means that heats the radiator so that the surface temperature of the radiator becomes 20°C to 50°C, The long-wavelength infrared radiation is irradiated without the radiator coming into contact with the frozen product. The thawing cabinet according to claim 7.

10. the radiator is a reflector having an anodized aluminum or aluminum alloy on a reflective surface, The radiator converts the short-wavelength infrared rays irradiated by the heating means into the long-wavelength infrared rays and irradiates the long-wavelength infrared rays onto the frozen product. The thawing cabinet according to claim 9.

11. A window made of resin or infrared-transmitting glass is provided to allow long-wavelength infrared rays emitted from a room temperature environment to enter the thawing chamber. The thawing cabinet according to claim 7.

12. In a low-temperature environment of -5°C to +5°C, a part of the wall has a thawing chamber that takes in infrared rays emitted from the room temperature environment (room temperature infrared rays). Thawing warehouse.

13. The wall material that captures room temperature infrared rays is infrared-transmitting glass or polyethylene resin. The thawing cabinet according to claim 12.

14. The walls, ceiling and floor (surrounding surfaces) other than the room temperature infrared intake wall are made of reflective material that reflects 95% or more of infrared rays in the wavelength range of 9 μm to 15 μm. The thawing cabinet according to claim 12.

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