Drying method, drying chamber, and method for manufacturing dried product

Abstract

Provided is a drying method in a device including: a drying section for drying a compound; a cooling unit for cooling the drying section; a temperature detection unit for detecting the internal temperature of the drying section and generating information about the internal temperature; and a control unit configured to control the internal temperature of the drying section by controlling the cooling unit using the information from the temperature detection unit. The drying method includes: (a) a step for maintaining, for a first predetermined period of time, the internal temperature of the drying section within a temperature range of −60°C to −18°C, which is a first temperature zone; and (b) a step for maintaining, for a second predetermined period of time, the internal temperature of the drying section within a temperature range higher than −18°C but lower than 0°C, which is a second temperature zone. The (b) step is executed in accordance with the value of a freezing point or an ice formation point set for the drying section.

Description

Drying method, drying cabinet, and method for manufacturing dried products

[0001] The present disclosure relates to a drying method, a drying cabinet, and a method for producing a dried product.

[0002] Patent Document 1 discloses a method for drying food, which includes the steps of maintaining the internal temperature of the storage compartment within a first temperature range of −60° C. or higher and −18° C. or lower for a first predetermined time, maintaining the internal temperature of the storage compartment within a second temperature range of higher than −18° C. and lower than 0° C. for a second predetermined time, and maintaining the internal temperature of the storage compartment within a third temperature range of 0° C. or higher for a third predetermined time.

[0003] International Publication No. 2020 / 175102

[0004] The present disclosure provides a drying method, a drying chamber, and a method for producing a dried product that can obtain a dried product suitable for its intended use.

[0005] In one aspect of the present disclosure, a drying method is provided in an apparatus including a drying section for drying a compound, a cooling unit for cooling the drying section, a temperature detection unit for detecting the internal temperature of the drying section and generating information related to the internal temperature, and a control unit configured to control the cooling unit using the information from the temperature detection unit to control the internal temperature of the drying section, the drying method comprising the steps of: (a) maintaining the internal temperature of the drying section within a first temperature range of −60° C. or higher and −18° C. or lower for a first predetermined time; and (b) maintaining the internal temperature of the drying section within a second temperature range of higher than −18° C. and lower than 0° C. for a second predetermined time, wherein step (b) is performed according to a freezing point or icing point value set for the drying section.

[0006] In addition, a drying chamber in one aspect of the present disclosure includes a drying section for drying a compound, a cooling unit for cooling the drying section, a temperature detection unit for detecting the internal temperature of the drying section and generating information related to the internal temperature, and a control unit configured to control the cooling unit using the information from the temperature detection unit to control the internal temperature of the drying section, wherein the control unit performs the following steps: (a) maintaining the internal temperature of the drying section within a first temperature range of −60°C or higher and −18°C or lower for a first predetermined time; and (b) maintaining the internal temperature of the drying section within a second temperature range of higher than −18°C and lower than 0°C for a second predetermined time, wherein step (b) is performed according to a freezing point or icing point value set for the drying section.

[0007] Furthermore, one aspect of the present disclosure provides a method for producing a dried product using an apparatus including a drying section for drying a compound, a cooling unit for cooling the drying section, a temperature detection unit for detecting the internal temperature of the drying section and generating information related to the internal temperature, and a control unit configured to control the cooling unit using the information from the temperature detection unit to control the internal temperature of the drying section, the method including the steps of: (a) placing the compound in the drying section; (b) maintaining the internal temperature of the drying section within a first temperature range of −60°C or higher and −18°C or lower for a first predetermined time; and (c) maintaining the internal temperature of the drying section within a second temperature range of higher than −18°C and lower than 0°C for a second predetermined time, wherein the step (c) is performed according to a freezing point or icing point value set for the drying section.

[0008] The drying method, drying chamber, and method for producing a dried product disclosed herein can produce a dried product suitable for its intended use.

[0009] Fig. 1 is a cross-sectional view of a drying chamber according to embodiment 1. Fig. 2 is a diagram showing temperature and humidity patterns in a drying process for a solid object according to embodiment 1. Fig. 3 is a diagram showing the results of a sensory evaluation of the dried product according to embodiment 1. Fig. 4 is a diagram showing temperature patterns in a drying process for a solid object according to embodiment 2. Fig. 5 is a diagram showing temperature patterns in a drying process for a liquid object according to embodiment 3. Fig. 6 is a diagram showing temperature patterns in a drying process for a liquid object according to embodiment 4.

[0010] (Findings, etc., that form the basis of the present disclosure) Conventional methods for drying food include thermal drying using hot air or microwaves, drying at low temperatures under reduced pressure, and natural drying. There is also a vacuum freeze-drying method, in which food is frozen and then dried by evaporating moisture through reduced pressure and vacuum. At the time the inventors arrived at the present disclosure, a food drying method existed that included the steps of: maintaining the internal temperature of a storage compartment within a first temperature range of −60°C or higher and −18°C or lower for a first predetermined time; maintaining the internal temperature of the storage compartment within a second temperature range of higher than −18°C and lower than 0°C for a second predetermined time; and maintaining the internal temperature of the storage compartment within a third temperature range of 0°C or higher for a third predetermined time. However, the inventors discovered a problem in that this method could not be applied to various applications of compounds other than food, such as solids and liquids, and was unable to produce dried products suitable for the intended use. To solve this problem, the present disclosure constituted the subject matter of the present disclosure.

[0011] Therefore, the present disclosure provides a drying method, a drying chamber, and a method for producing a dried product that can obtain a dried product suitable for its intended use.

[0012] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of already well-known matters or redundant description of substantially the same configuration may be omitted.

[0013] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0014] First Embodiment Hereinafter, a first embodiment will be described with reference to FIGS.

[0015] [1-1. Configuration] FIG. 1 shows a cross section of a drying chamber according to a first embodiment of the present invention.

[0016] In Fig. 1, a drying chamber main body 1 is insulated from the outside by an insulating box body 2. The interior of the drying chamber main body 1 is divided by a partition 3 into an upper cooling chamber 4 and a lower dry storage chamber 5. The drying chamber is equipped with a cooler 6 inside the cooling chamber 4. The dry storage chamber 5 corresponds to an example of a "drying section" in the present disclosure.

[0017] The blower 7 forcibly ventilates the low-humidity cold air generated by the cooler 6. The heating means 8 is, for example, a sheath heater, and adjusts the temperature of the air flowing into the dry storage chamber 5 by heating the above-mentioned cold air.

[0018] The drying cabinet is provided with an air duct 9 at the rear of the dry storage chamber 5, which blows air generated by the cooler 6 and heated by the heating means 8 to each shelf in the dry storage chamber 5. In Fig. 1, arrows indicate the flow of air. The cooler 6, the blower 7, and the air duct 9 correspond to an example of the "cooling unit" of the present disclosure.

[0019] A temperature sensor 10 serving as a temperature detection means is installed in the dry storage chamber 5. The temperature sensor 10 corresponds to an example of a "temperature detection unit" in the present disclosure.

[0020] The drying chamber main body 1 is equipped with a control means (not shown) that controls the operation of each part and device. The control means can control the operation of each part and device in response to user instructions entered through an operation panel (not shown) provided on the drying chamber main body 1. The control means corresponds to an example of a "control unit" in the present disclosure. The control means includes, for example, a processor and a memory that stores a program executed by the processor. The processor may execute the program to control the operation of each part and device. The control means controls the cooler 6, the blower 7, and the heating means 8 using information from the temperature sensor 10 to control the internal temperature of the drying storage chamber 5.

[0021] [1-2. Operation] Here, the drying process of the drying chamber in the present embodiment 1 will be described using an example in which solid object A, which is solid at room temperature, is stored in the drying storage chamber 5. Solid object A corresponds to an example of a "compound" in the present disclosure. Note that the compound is preferably something other than a food product.

[0022] First, the user places solid material A in the drying storage chamber 5, operates a switch on the operation panel to select "Drying Course 1," and then inputs information about the compound to be placed (e.g., freezing point, type, and weight) using the compound information input means (not shown) on the operation panel, and operates the drying chamber. "Drying Course 1" dries the compound using a temperature pattern (Figure 2) set based on the input compound information. Here, the temperature pattern can be selected for each course, such as "Drying Course 1," depending on the freezing point, type, and weight of the compound to be placed.

[0023] The solid A is composed of, for example, various organic compounds, and the completed dried product can be used as is or dissolved in various solvents depending on its intended use.

[0024] 2, the control means starts adjusting the amount of cool air flowing into the dry storage chamber 5 by the blower 7 so that the temperature reaches a preset temperature of the first temperature zone (-20°C, for example). After the temperature sensor 10 detects the preset temperature of the first temperature zone (-20°C, for example), the control means maintains the set temperature for a preset time (360 minutes, for example).

[0025] The control means again starts adjusting the temperature of the cool air flowing into the dry storage chamber 5 using the blower 7 so that the temperature becomes the set temperature of the second temperature zone (-5°C for example). In this case, air heated by the heating means 8 is flowed into the dry storage chamber 5. The control means increases the temperature in stages from the set temperature of the first temperature zone (-20°C for example) to the set temperature of the second temperature zone (-5°C for example). Note that the control means may also increase the temperature continuously from the set temperature of the first temperature zone (-20°C for example) to the set temperature of the second temperature zone (-5°C for example).

[0026] In the first embodiment, after the start of storage, solid material A is first frozen in the first temperature zone by cooling to a set temperature (-20°C, for example) and maintaining the temperature. The first temperature zone is preferably a temperature lower than the freezing point (icing point) of solid material A. Here, the freezing point (icing point) refers to the temperature at which water contained in the compound begins to freeze. Furthermore, the first temperature zone is preferably within a temperature range of -60°C or higher and -18°C or lower. Next, the temperature is raised to a second temperature zone (-5°C, for example), thereby generating a vapor pressure difference. By maintaining the second temperature zone for a predetermined time (6,400 minutes, for example), the relative humidity in the dry storage chamber gradually decreases, eventually reaching approximately 8%. This progresses the drying of solid material A. Since solid material A is maintained in the freezing temperature zone throughout, it can be dried in an environment free of the risk of microbial growth. The second temperature zone is preferably higher than the first temperature zone and is within the freezing temperature zone. Furthermore, the second temperature zone is preferably within a temperature range of higher than -18°C and lower than 0°C.

[0027] Furthermore, since the freezing point of solid material A is −10° C., the water contained in solid material A does not freeze in the second temperature zone. As the water contained in solid material A evaporates, the drying of solid material A progresses, and by maintaining the set temperature of the second temperature zone for a preset time (6,400 minutes in this example), a dried product of solid material A is completed.

[0028] In addition, when solid objects that are not easily damaged by temperature are to be dried, a step (c) of maintaining the internal temperature of the drying compartment within a third temperature range of 0°C or higher for a third predetermined time may be performed. This further increases the set temperature, improving drying efficiency and shortening the drying time. Furthermore, the control means may increase the internal temperature of the drying compartment in stages from the second temperature range to the third temperature range.

[0029] The drying chamber may also be equipped with a heating unit or an infrared radiation unit. In this case, the heating unit or the infrared radiation unit can be used to maintain the set temperature or to heat the solid material A to the second or third temperature range. The heating unit or the infrared radiation unit enables more precise temperature maintenance with less temperature fluctuation, shortens the time required to reach the second or third temperature range, and efficiently dries the solid material A.

[0030] The drying cabinet may also be equipped with an ultraviolet ray irradiation unit. In this case, when the room temperature of the drying storage chamber 5 is controlled by the control means according to the above temperature pattern, drying can be performed in an environment where bacterial growth is suppressed, thereby further improving safety.

[0031] The quality evaluation results are shown in Figure 3. As a conventional example, solid material A from the same lot as that of the first embodiment was used, which was dried with hot air at 70°C for 10 hours. Compared to the conventional example, solid material A of the first embodiment showed no discoloration in appearance. If solid material A of the first embodiment is taken as the reference 0, the conventional example showed discoloration of -2 points. It is believed that this discoloration was caused by a change in components due to heat.

[0032] In this first embodiment, drying is performed below freezing throughout, which suppresses chemical reactions such as oxidation. Furthermore, in this first embodiment, the room temperature of the dry storage chamber 5 is maintained at -5°C, which is higher than the freezing point of -10°C, so the room temperature does not reach the freezing point and ice crystals do not form. Therefore, the solid material A dries without being damaged by ice crystals. Furthermore, the promotion of chemical reactions due to the freeze concentration effect caused by the formation of ice crystals is also suppressed.

[0033] The first embodiment can also be applied to samples that are susceptible to chemical reactions due to temperature, samples that are structurally fragile and susceptible to damage from ice crystals, and samples that contain highly chemically reactive components such as enzymes, such as biological samples.

[0034] Furthermore, if the freezing point of the solid material to be dried is lower than the set temperature of the first temperature zone, it will not freeze even in the first temperature zone, so it can be dried below freezing without any damage caused by ice crystals.

[0035] In the first embodiment, the control means maintains the temperature in the first temperature range (-20°C for example) for a predetermined time (360 minutes for example), and then maintains the temperature in the second temperature range (-5°C for example) for a predetermined time (6400 minutes for example) to complete the dried product.

[0036] [1-3. Effects, etc.] As is clear from the above, the drying method of the first embodiment is a drying method in an apparatus including a drying section for drying a compound, a cooling section for cooling the drying section, a temperature detection section for detecting the internal temperature of the drying section and generating information about the internal temperature, and a control section configured to control the cooling section using information from the temperature detection section to control the internal temperature of the drying section, the drying method including: (a) maintaining the internal temperature of the drying section within a first temperature range of −60° C. or higher and −18° C. or lower for a first predetermined time; and (b) maintaining the internal temperature of the drying section within a second temperature range of higher than −18° C. and lower than 0° C. for a second predetermined time, wherein step (b) is performed according to the freezing point or icing point value set for the drying section. As a result, a dried product can be obtained in which the solid material placed in the drying section maintains its pre-drying state without denaturation or damage to the components during drying.

[0037] Second Embodiment A second embodiment will be described below with reference to Fig. 4. Description of content that overlaps with the content described in the first embodiment will be omitted.

[0038] [2-1. Configuration] The configuration is the same as in the first embodiment, so a description thereof will be omitted.

[0039] [2-2. Operation] Here, the drying process of the drying chamber in the present embodiment 2 will be described using as an example a case where solid material B, which is solid at room temperature, is stored in the dry storage chamber 5. Solid material B corresponds to an example of the "compound" in the present disclosure.

[0040] First, the user places solid material B in the drying storage chamber 5, operates a switch on the operation panel to select "Drying Course 2," and then inputs information about the compound to be placed (e.g., freezing point, type, and weight) using the compound information input means (not shown) on the operation panel, and operates the drying chamber. "Drying Course 2" dries the compound using a temperature pattern (Figure 4) set based on the input compound information. Here, the temperature pattern can be selected for each course, such as "Drying Course 2," depending on the freezing point, type, and weight of the compound to be placed.

[0041] The solid substance B is composed of various organic compounds, and the completed dried product can be used as is or dissolved in various solvents depending on the application.

[0042] 4, the control means starts adjusting the amount of cool air flowing into the dry storage chamber 5 by the blower 7 so that the temperature reaches the preset temperature of the first temperature zone (−23° C., for example). After the temperature sensor 10 detects the preset temperature of the first temperature zone (−23° C., for example), the control means maintains the set temperature for a preset time (850 minutes, for example).

[0043] The control means again starts adjusting the temperature of the cold air flowing into the dry storage chamber 5 using the blower 7 so that the temperature reaches the set temperature of the second temperature zone (for example, -7°C). The control means gradually increases the temperature from the set temperature of the first temperature zone (for example, -23°C) to the set temperature of the second temperature zone (for example, -7°C). The control means may also continuously increase the temperature from the set temperature of the first temperature zone (for example, -23°C) to the set temperature of the second temperature zone (for example, -7°C). Since the freezing point of solid material B is -5°C, solid material B remains frozen even in the second temperature zone. The moisture contained in solid material B sublimes, causing solid material B to dry. The dried product of solid material B is completed by maintaining the set temperature of the second temperature zone for a predetermined time (for example, 4,770 minutes).

[0044] In the second embodiment, after the start of storage, solid material B is first frozen in the first temperature range by cooling to a set temperature (-20°C in this example) and maintaining that temperature. Next, the temperature is raised to a second set temperature (-7°C in this example), which generates a vapor pressure difference. Drying of solid material B proceeds by maintaining the second temperature range for a predetermined time. As in the first embodiment, the relative humidity is ultimately reduced to 10% or less, and drying proceeds throughout in the freezing temperature range, allowing solid material B to be dried in an environment free of the risk of microbial growth.

[0045] Furthermore, since the freezing point of solid material B is −5° C., the water contained in solid material B remains frozen in the second temperature zone. As water sublimes from the ice crystals contained in solid material B, the drying of solid material B progresses, and by maintaining the set temperature of the second temperature zone for a preset time (4,770 minutes in this example), a dried product of solid material B is completed.

[0046] In addition, when solid objects that are not easily damaged by temperature are to be dried, a step (c) of maintaining the internal temperature of the drying compartment within a third temperature range of 0°C or higher for a third predetermined time may be performed. This further increases the set temperature, improving drying efficiency and shortening the drying time. Furthermore, the control means may increase the internal temperature of the drying compartment in stages from the second temperature range to the third temperature range.

[0047] The drying chamber may also be equipped with a heating unit or an infrared radiation unit. In this case, the heating unit or the infrared radiation unit can be used to maintain the set temperature or to heat the solid material B to the second or third temperature range. The heating unit or the infrared radiation unit enables more precise temperature maintenance with less temperature fluctuation, shortens the time required to reach the second or third temperature range, and efficiently dries the solid material B.

[0048] The drying cabinet may also be equipped with an ultraviolet ray irradiation unit. In this case, when the room temperature of the drying storage chamber 5 is controlled by the control means according to the above temperature pattern, drying can be performed in an environment where bacterial growth is suppressed, thereby further improving safety.

[0049] As a conventional example, solid material B from the same lot as in Embodiment 2 was frozen and dried for several days by freeze-drying (vacuum freeze-drying), which involves depressurizing the material to a vacuum and drying it. Although not shown in the figure, the structure of solid material B in Embodiment 2 is porous like the conventional product, but has relatively large pores and a thick skeleton (partition walls). The moisture content of solid material B is higher than in the conventional example, and moisture can be stored in the thick skeleton (partition walls). Therefore, this method of drying can be said to be effective when it is desired to impart flexibility and elasticity to a dried product that is not available in the conventional example.

[0050] In this second embodiment, drying is performed below freezing throughout, which also suppresses chemical reactions such as oxidation. This second embodiment can also be applied to samples that are susceptible to chemical reactions due to temperature, or samples that contain highly chemically reactive components such as enzymes, such as biological samples.

[0051] In the second embodiment, a preset temperature (-23°C for example) in a first temperature range is maintained for a preset time (850 minutes for example), followed by a preset temperature (-7°C for example) for a preset time (4770 minutes for example) to complete the dried product.

[0052] [2-3. Effects, etc.] As is clear from the above, the drying method of the second embodiment is a drying method in an apparatus including a drying section for drying a compound, a cooling section for cooling the drying section, a temperature detection section for detecting the internal temperature of the drying section and generating information about the internal temperature, and a control section configured to control the cooling section using information from the temperature detection section to control the internal temperature of the drying section, the drying method including: (a) maintaining the internal temperature of the drying section within a first temperature range of −60° C. or higher and −18° C. or lower for a first predetermined time; and (b) maintaining the internal temperature of the drying section within a second temperature range of higher than −18° C. and lower than 0° C. for a second predetermined time, wherein step (b) is performed according to the freezing point or icing point value set for the drying section. As a result, the solid material placed in the drying section can be dried without denaturing or damaging the components during drying, allowing a moderate amount of moisture to remain, resulting in a dried product with unprecedented flexibility and elasticity.

[0053] Third Embodiment Hereinafter, a third embodiment will be described with reference to Fig. 5. Descriptions of contents that overlap with those described in the first and second embodiments will be omitted.

[0054] [3-1. Configuration] The configuration is the same as in the first and second embodiments, so a description thereof will be omitted.

[0055] [3-2. Operation] Here, the drying process of the drying chamber in the present embodiment 3 will be described using as an example a case where a liquid substance C that is liquid at room temperature is stored in the dry storage chamber 5. The liquid substance C corresponds to an example of a "compound" in the present disclosure.

[0056] First, the user places liquid C in the drying storage chamber 5, operates a switch on the operation panel to select "Drying Course 3," and then inputs information about the compound to be placed (e.g., freezing point, type, and weight) using the compound information input means (not shown) on the operation panel, and operates the drying chamber. "Drying Course 3" dries the compound using a temperature pattern (Figure 5) set based on the input compound information. Here, the temperature pattern can be selected for each course, such as "Drying Course 3," depending on the freezing point, type, and weight of the compound to be placed.

[0057] The liquid C is composed of various organic compounds, and the completed dried product can be used as is or dissolved in various solvents depending on the application.

[0058] 5, the control means starts adjusting the amount of cool air flowing into the dry storage chamber 5 by the blower 7 so that the temperature reaches a preset temperature (-24°C in this example) in the first temperature zone. After the temperature sensor 10 detects the preset temperature (-24°C in this example), the control means maintains the set temperature for a preset time (590 minutes in this example).

[0059] The control means again starts adjusting the temperature of the cold air flowing into the dry storage chamber 5 using the blower 7 so that the temperature reaches the set temperature of the second temperature zone (for example, -2°C). The control means gradually increases the temperature from the set temperature of the first temperature zone (for example, -24°C) to the set temperature of the second temperature zone (for example, -2°C). The control means may also continuously increase the temperature from the set temperature of the first temperature zone (for example, -24°C) to the set temperature of the second temperature zone (for example, -2°C). Since the freezing point of liquid C is -3°C, liquid C does not freeze even in the second temperature zone. As the moisture contained in liquid C evaporates, the liquid C dries, and by maintaining the set temperature of the second temperature zone for a predetermined time (for example, 6,150 minutes), a dried product of liquid C is completed.

[0060] In the third embodiment, after the start of storage, the liquid C is first frozen by cooling to a set temperature (-24°C in this example) in the first temperature range and maintaining that temperature. Next, the temperature is raised to a second set temperature (-2°C in this example), which generates a vapor pressure difference. The second temperature range is maintained for a predetermined time, which causes the liquid C to dry. As in the first embodiment, the relative humidity is ultimately reduced to 10% or less, and the drying proceeds throughout in the freezing temperature range, so that the liquid C can be dried in an environment free of the risk of microbial growth.

[0061] In addition, when targeting liquid objects that are not easily damaged by temperature, a step (c) of maintaining the internal temperature of the drying compartment within a third temperature range of 0°C or higher for a third predetermined time may be performed. This further increases the set temperature, improving drying efficiency and shortening the drying time. Furthermore, the control means may increase the internal temperature of the drying compartment in stages from the second temperature range to the third temperature range.

[0062] The drying chamber may also be equipped with a heating unit or an infrared radiation unit. In this case, the heating unit or the infrared radiation unit can be used to maintain the set temperature or to heat the liquid C to the second or third temperature range. The heating unit or the infrared radiation unit enables more precise temperature maintenance with less temperature fluctuation, shortens the time it takes to reach the second or third temperature range, and allows the liquid C to be dried efficiently.

[0063] The drying cabinet may also be equipped with an ultraviolet ray irradiation unit. In this case, when the room temperature of the drying storage chamber 5 is controlled by the control means according to the above temperature pattern, drying can be performed in an environment where bacterial growth is suppressed, thereby further improving safety.

[0064] As a conventional example, a comparison was made with a product obtained by freezing the same lot of liquid C as in the third embodiment and drying it for several days using freeze-drying (vacuum freeze-drying), which involves reducing the pressure to a vacuum and drying. The dried product of liquid C in the third embodiment has a structure similar to that of the conventional example, with a structure similar to that of the conventional example. During the drying process, moisture gradually evaporates from the surface, and drying progresses. This is a mild drying process that utilizes the vapor pressure difference at atmospheric pressure, so there is no pressure change like in the conventional example and it is less susceptible to damage. On the other hand, the conventional example has a porous structure, and the skeleton (partition walls) is thin and delicate, so the vacuum created during the drying process causes pressure changes and the structure may be damaged.

[0065] Furthermore, in this third embodiment, drying is performed below freezing throughout, so chemical reactions such as oxidation are suppressed, as in the conventional example. Furthermore, unlike the conventional example, in this third embodiment, the room temperature of the dry storage chamber 5 is maintained at -2°C, which is higher than the freezing point of -3°C, so the room temperature does not reach the freezing point and ice crystals do not form. Therefore, the liquid C dries without being damaged by ice crystals. Furthermore, the promotion of chemical reactions due to the freeze concentration effect caused by the formation of ice crystals is also suppressed.

[0066] This third embodiment can also be applied to samples that are susceptible to chemical reactions due to temperature, samples that are structurally fragile and susceptible to damage from ice crystals, and samples that contain highly chemically reactive components such as enzymes, such as biological samples.

[0067] Furthermore, if the freezing point of the liquid to be dried is lower than the set temperature of the first temperature zone, the liquid will not freeze even in the first temperature zone, so it can be dried below freezing without any damage caused by ice crystals.

[0068] In the third embodiment, the control means maintains the temperature in the first temperature range (-24°C for example) for a predetermined time (590 minutes for example), and then maintains the temperature in the second temperature range (-2°C for example) for a predetermined time (6150 minutes for example) to complete the dried product.

[0069] [3-3. Effects, etc.] As is clear from the above, the drying method of the third embodiment is a drying method in an apparatus including a drying section for drying a compound, a cooling section for cooling the drying section, a temperature detection section for detecting the internal temperature of the drying section and generating information about the internal temperature, and a control section configured to control the cooling section using information from the temperature detection section to control the internal temperature of the drying section, the drying method including: (a) maintaining the internal temperature of the drying section within a first temperature range of −60°C or higher and −18°C or lower for a first predetermined time; and (b) maintaining the internal temperature of the drying section within a second temperature range of higher than −18°C and lower than 0°C for a second predetermined time, wherein step (b) is performed according to the freezing point or icing point value set for the drying section. As a result, a liquid placed in the drying section can be dried to a dried product that maintains its pre-drying state without denaturing or damaging the components during drying.

[0070] (Fourth Embodiment) Hereinafter, a fourth embodiment will be described with reference to Fig. 6. Description of the contents that overlap with the contents described in the first, second, and third embodiments will be omitted.

[0071] [4-1. Configuration] The configuration is the same as in the first, second and third embodiments, so a description thereof will be omitted.

[0072] [4-2. Operation] Here, the drying process of the drying chamber in the present embodiment 4 will be described using as an example a case where a liquid substance D that is liquid at room temperature is stored in the dry storage chamber 5. The liquid substance D corresponds to an example of the "compound" in the present disclosure.

[0073] First, the user places the liquid substance D in the drying storage chamber 5, operates a switch on the operation panel to select "Drying Course 4," and then inputs information about the compound to be placed (e.g., freezing point, type, and weight) using the compound information input means (not shown) on the operation panel, and operates the drying chamber. "Drying Course 4" dries the compound using a temperature pattern (Figure 6) set based on the input compound information. Here, the temperature pattern can be selected for each course, such as "Drying Course 4," depending on the freezing point, type, and weight of the compound to be placed.

[0074] The liquid D is composed of various organic compounds, and the completed dried product is used as is or dissolved in various solvents depending on the application.

[0075] 6, the control means starts adjusting the temperature of the cool air flowing into the dry storage chamber 5 by the blower 7 so that the temperature becomes the preset temperature (-21°C for example) of the first temperature zone. After the temperature sensor 10 detects the preset temperature (-21°C for example), the control means maintains the set temperature for a preset time (1030 minutes for example).

[0076] The control means again starts adjusting the amount of cold air flowing into the dry storage chamber 5 using the blower 7 so that the temperature reaches the set temperature of the second temperature zone (for example, -7°C). The control means gradually increases the temperature from the set temperature of the first temperature zone (for example, -21°C) to the set temperature of the second temperature zone (for example, -7°C). The control means may also continuously increase the temperature from the set temperature of the first temperature zone (for example, -21°C) to the set temperature of the second temperature zone (for example, -7°C). Since the freezing point of the liquid D is -5°C, the liquid D remains frozen even in the second temperature zone. The moisture contained in the liquid D sublimates, causing the liquid D to dry. The dried liquid D is then completed by maintaining the set temperature of the second temperature zone for a predetermined time (for example, 5,500 minutes).

[0077] In the fourth embodiment, after the start of storage, the liquid D is first frozen by cooling to a set temperature (-21°C in this example) in the first temperature range and maintaining that temperature. Next, the temperature is raised to a second set temperature (-7°C in this example), which generates a vapor pressure difference. The second temperature range is maintained for a predetermined time, which causes the liquid D to dry. As in the first embodiment, the relative humidity is ultimately reduced to 10% or less, and the drying proceeds throughout in the freezing temperature range, so that the liquid D can be dried in an environment free of the risk of microbial growth.

[0078] Furthermore, since the freezing point of liquid D is −5° C., the water contained in liquid D remains frozen in the second temperature range. The drying of liquid D progresses as water sublimes from the ice crystals contained in liquid D, and by maintaining the set temperature of the second temperature range for a preset time (5,500 minutes in this example), a dried product of liquid D is completed.

[0079] In addition, when targeting liquid objects that are not easily damaged by temperature, a step (c) of maintaining the internal temperature of the drying compartment within a third temperature range of 0°C or higher for a third predetermined time may be performed. This further increases the set temperature, improving drying efficiency and shortening the drying time. Furthermore, the control means may increase the internal temperature of the drying compartment in stages from the second temperature range to the third temperature range.

[0080] The drying chamber may be equipped with a heating unit or an infrared radiation unit. In this case, the heating unit or the infrared radiation unit can be used to maintain the set temperature or to heat the liquid D to the second or third temperature range. The heating unit or the infrared radiation unit enables more precise temperature maintenance with less temperature fluctuation, shortens the time it takes to reach the second or third temperature range, and allows the liquid D to be dried efficiently.

[0081] The drying cabinet may also be equipped with an ultraviolet ray irradiation unit. In this case, when the room temperature of the drying storage chamber 5 is controlled by the control means according to the above temperature pattern, drying can be performed in an environment where bacterial growth is suppressed, thereby further improving safety.

[0082] As a conventional example, a comparison was made with a liquid material D from the same lot as in the fourth embodiment, which was frozen and dried for several days using freeze-drying (vacuum freeze-drying), a method in which the liquid material D was dried under a vacuum. Although not shown in the figure, the structure of the liquid material D in the fourth embodiment is porous like the conventional example, but the pores are larger and the material has a thicker skeleton (partition walls). The moisture content of the liquid material D is higher than in the conventional example, and moisture can be stored in the thicker skeleton (partition walls). This gives the finished dried product a soft feel, making this drying method effective when imparting flexibility and elasticity not found in the conventional example. Furthermore, because viscosity is generated, the structure is less likely to collapse during or after the drying process, and a decrease in yield can be suppressed.

[0083] In this fourth embodiment, drying is carried out below freezing point throughout, as in the conventional example, so chemical reactions such as oxidation are suppressed, and the sample can be applied to samples that are prone to chemical reactions due to temperature, or samples that contain highly chemically reactive components such as enzymes, such as biological samples.

[0084] In the fourth embodiment, the control means maintains the temperature in the first temperature range (-21°C for example) for a predetermined time (1030 minutes for example), and then maintains the temperature in the second temperature range (-7°C for example) for a predetermined time (5500 minutes for example), completing the dried product.

[0085] [4-3. Effects, etc.] As is clear from the above, the drying method of Embodiment 4 is a drying method in an apparatus including a drying compartment for drying a compound, a cooling unit for cooling the drying compartment, a temperature detection unit for detecting the internal temperature of the drying compartment and generating information related to the internal temperature, and a control unit configured to control the cooling unit using the information from the temperature detection unit to control the internal temperature of the drying compartment, and includes the steps of: (a) maintaining the internal temperature of the drying compartment within a first temperature range of −60° C. or higher and −18° C. or lower for a first predetermined time; and (b) maintaining the internal temperature of the drying compartment within a second temperature range of higher than −18° C. and lower than 0° C. for a second predetermined time, wherein step (b) is performed according to the freezing point or icing point value set for the drying compartment. This prevents the liquid materials placed in the drying section from denaturing or being damaged during drying, and allows a moderate amount of moisture to remain, providing the dried product with the flexibility and elasticity that was previously not available, as well as viscosity, which prevents the dried product from collapsing during the drying process and allows for a high yield of dried products.

[0086] (Other Embodiments) As described above, the first, second, third, and fourth embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to these, and can also be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is possible to combine the components described in the first, second, third, and fourth embodiments to create new embodiments.

[0087] Therefore, other embodiments will be exemplified below.

[0088] In other embodiments, the drying chamber may be configured to perform the drying methods described in embodiments 1, 2, 3, and 4.

[0089] In other embodiments, the drying methods described in the first, second, third, and fourth embodiments may be carried out as methods for producing dried products.

[0090] In the first, second, third, and fourth embodiments, solid A, solid B, liquid C, and liquid D, each having a different freezing point, have been described as examples of compounds. The compounds are preferably other than food, but may contain food.

[0091] In another embodiment, a second temperature sensor may be provided to detect the temperature inside the compound in the drying section. The second temperature sensor may be, for example, an infrared sensor. If the temperature change detected by the second temperature sensor remains constant for a predetermined period of time, the temperature may be calculated as the freezing point or icing point.

[0092] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0093] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0094] (Technology 1) A drying method for an apparatus including a drying section for drying a compound, a cooling unit for cooling the drying section, a temperature detection unit for detecting an internal temperature of the drying section and generating information related to the internal temperature, and a control unit configured to control the cooling unit using the information from the temperature detection unit to control the internal temperature of the drying section, the drying method comprising: (a) a step of maintaining the internal temperature of the drying section within a first temperature range of −60°C or higher and −18°C or lower for a first predetermined time; and (b) a step of maintaining the internal temperature of the drying section within a second temperature range of higher than −18°C and lower than 0°C for a second predetermined time, wherein step (b) is performed according to a freezing point or icing point value set for the drying section.

[0095] This configuration makes it possible to obtain dried products suitable for various uses of compounds including solids and liquids.

[0096] (Technology 2) In addition to the steps (a) and (b), the drying method according to Technology 1 further comprises a step (c) of maintaining the internal temperature of the drying section within a third temperature range of 0°C or higher for a third predetermined time.

[0097] According to this configuration, the temperature is increased to 0° C. or higher, which accelerates drying and allows for efficient drying.

[0098] (Technology 3) The drying method according to Technology 1 or 2, wherein at least the step (b) includes maintaining the internal temperature of the drying section at a freezing point or a temperature higher than the freezing point.

[0099] According to this configuration, the compound placed in the drying section does not generate ice crystals even at temperatures below freezing, and drying can proceed in an unfrozen state.

[0100] (Technology 4) The drying method according to Technology 1 or 2, wherein at least the step (b) includes maintaining the internal temperature of the drying section at a freezing point or a temperature lower than the freezing point.

[0101] According to this configuration, ice crystals are generated in the compound placed in the drying section, and drying can proceed in a frozen state.

[0102] (Technology 5) The drying method according to any one of Techniques 1 to 4, wherein the step (a) includes increasing the internal temperature of the drying section stepwise within the temperature range of the first temperature zone.

[0103] This configuration increases the time during which there is a difference between the surface temperature of the compound placed in the drying section and the internal temperature of the drying section, thereby promoting the sublimation and evaporation of water due to the difference in saturated water vapor pressure.

[0104] (Technology 6) The drying method according to any one of Techniques 1 to 5, wherein the step (b) includes increasing the internal temperature of the drying section stepwise within the range of the second temperature zone.

[0105] This configuration increases the time during which there is a difference between the surface temperature of the compound placed in the drying section and the internal temperature of the drying section, thereby promoting the sublimation and evaporation of water due to the difference in saturated water vapor pressure.

[0106] (Technology 7) The drying method according to Technology 2, wherein the step (c) includes increasing the internal temperature of the drying section stepwise within the range of the third temperature zone.

[0107] This configuration increases the time during which there is a difference between the surface temperature of the compound placed in the drying section and the internal temperature of the drying section, thereby promoting evaporation of water due to the difference in saturated water vapor pressure.

[0108] (Technology 8) The drying method according to any one of technologies 1 to 7, wherein the device includes a second temperature detection unit that detects the temperature inside the compound in the drying section and generates information about the temperature inside the compound, and a freezing point or icing point value is calculated based on the information from the second temperature detection unit.

[0109] According to this configuration, the compound can be dried using a drying method that is more suitable for the compound.

[0110] (Technology 9) The drying method according to any one of Technologies 1 to 8, wherein the device includes a heating unit that heats the inside of the drying compartment, and the control unit is configured to control the internal temperature of the drying compartment using the heating unit.

[0111] This configuration allows for efficient temperature rise and shorter drying times.

[0112] (Technology 10) The drying method according to any one of Techniques 1 to 9, wherein the device includes a far-infrared irradiating unit that irradiates the inside of the drying section with far-infrared rays.

[0113] This configuration allows for more efficient heating and shorter drying times.

[0114] (Technology 11) The drying method according to any one of Techniques 1 to 10, wherein the device includes an ultraviolet irradiation unit that irradiates ultraviolet rays into the inside of the drying section.

[0115] This configuration further suppresses the growth of microorganisms and allows for safe drying.

[0116] (Technology 12) A drying cabinet comprising: a drying compartment for drying a compound; a cooling unit for cooling the drying compartment; a temperature detection unit for detecting an internal temperature of the drying compartment and generating information relating to the internal temperature; and a control unit configured to control the cooling unit using the information from the temperature detection unit to control the internal temperature of the drying compartment, wherein the control unit executes the following steps: (a) maintaining the internal temperature of the drying compartment within a first temperature range of −60° C. or higher and −18° C. or lower for a first predetermined time; and (b) maintaining the internal temperature of the drying compartment within a second temperature range of higher than −18° C. and lower than 0° C. for a second predetermined time; and wherein step (b) is executed in accordance with a freezing point or icing point value set for the drying compartment.

[0117] According to this configuration, by using a drying chamber as a dedicated chamber, it is possible to dry a large amount of samples.

[0118] (Technology 13) A method for producing a dried product using an apparatus including: a drying section for drying a compound; a cooling unit for cooling the drying section; a temperature detection unit for detecting an internal temperature of the drying section and generating information related to the internal temperature; and a control unit configured to control the cooling unit using the information from the temperature detection unit to control the internal temperature of the drying section, the method comprising: (a) a step of placing a compound in the drying section; (b) a step of maintaining the internal temperature of the drying section within a first temperature range of −60° C. or higher and −18° C. or lower for a first predetermined time; and (c) a step of maintaining the internal temperature of the drying section within a second temperature range of higher than −18° C. and lower than 0° C. for a second predetermined time, wherein the step (c) is performed depending on a freezing point or icing point value set for the drying section.

[0119] This configuration allows the production of dried products suitable for industrial mass production.

[0120] (Technology 14) The method for producing a dried product according to Technology 13, further comprising, in addition to the steps (a), (b), and (c), a step (d) of maintaining the internal temperature of the drying section within a third temperature range of 0°C or higher for a third predetermined time.

[0121] According to this configuration, the temperature is increased to 0°C or higher, which accelerates drying and allows for efficient production of dried products.

[0122] Since the present disclosure can appropriately control the temperature during drying of a compound, it can also be applied to applications in which inorganic substances other than organic substances are dried by changing the drying temperature and maintenance time to control the chemical reaction.

[0123] REFERENCE SIGNS LIST 1 Drying chamber body 2 Insulated box body 3 Partition 4 Cooling chamber 5 Drying storage chamber 6 Cooler 7 Fan 8 Heating means 9 Air passage 10 Temperature sensor

Claims

1. A drying method in an apparatus comprising: a drying section for drying a compound; a cooling unit for cooling the drying section; a temperature detection unit for detecting an internal temperature of the drying section and generating information relating to the internal temperature; and a control unit configured to control the cooling unit using the information from the temperature detection unit to control the internal temperature of the drying section, the drying method comprising: (a) a step of maintaining the internal temperature of the drying section within a first temperature range of -60°C or higher and -18°C or lower for a first predetermined time; and (b) a step of maintaining the internal temperature of the drying section within a second temperature range of higher than -18°C and lower than 0°C for a second predetermined time, wherein the step (b) is performed according to a freezing point or ice point value set for the drying section.

2. The drying method according to claim 1, further comprising, in addition to steps (a) and (b), a step (c) of maintaining the internal temperature of the drying section within a third temperature range of 0° C. or higher for a third predetermined period of time.

3. A method for drying according to claim 1 or 2, wherein at least step (b) comprises maintaining the internal temperature of the drying section at or above the freezing point.

4. A method for drying according to claim 1 or 2, wherein at least step (b) comprises maintaining the internal temperature of the drying section at or below the freezing point.

5. A drying method according to claim 1 or 2, wherein step (a) includes gradually increasing the internal temperature of the drying section within the temperature range of the first temperature zone.

6. A drying method according to claim 1 or 2, wherein step (b) comprises increasing the internal temperature of the drying section stepwise within the range of the second temperature zone.

7. The drying method according to claim 2, wherein the step (c) comprises increasing the internal temperature of the drying section stepwise within the range of the third temperature zone.

8. A method of drying according to claim 1 or 2, wherein the apparatus comprises a second temperature sensing unit for sensing a temperature inside the compound in the drying section to generate information relating to a temperature inside the compound, and further comprising the step of calculating a freezing point or frost point value based on the information from the second temperature sensing unit.

9. A drying method according to claim 1 or 2, wherein the device is provided with a heating unit that heats the inside of the drying compartment, and the control unit is configured to control the internal temperature of the drying compartment using the heating unit.

10. A drying method according to claim 1 or 2, wherein the device is provided with a far-infrared irradiation section which irradiates the inside of the drying section with far-infrared rays.

11. The drying method according to claim 1 or 2, wherein the device is provided with an ultraviolet irradiation section for irradiating the inside of the drying section with ultraviolet rays.

12. A drying cabinet comprising: a drying section for drying a compound; a cooling unit for cooling the drying section; a temperature detection unit for detecting an internal temperature of the drying section and generating information relating to the internal temperature; and a control unit configured to control the cooling unit using the information from the temperature detection unit to control the internal temperature of the drying section, wherein the control unit performs the following steps: (a) maintaining the internal temperature of the drying section within a first temperature range of -60°C or higher and -18°C or lower for a first predetermined time; and (b) maintaining the internal temperature of the drying section within a second temperature range of higher than -18°C and lower than 0°C for a second predetermined time, wherein step (b) is performed depending on the freezing point or ice point value set for the drying section.

13. A method for producing a dried product using an apparatus including a drying section for drying a compound, a cooling unit for cooling the drying section, a temperature detection unit for detecting an internal temperature of the drying section and generating information regarding the internal temperature, and a control unit configured to control the cooling unit using information from the temperature detection unit to control the internal temperature of the drying section, the method comprising: (a) a step of placing a compound in the drying section; (b) a step of maintaining the internal temperature of the drying section within a first temperature range of -60°C or higher and -18°C or lower for a first predetermined time; and (c) a step of maintaining the internal temperature of the drying section within a second temperature range of higher than -18°C and lower than 0°C for a second predetermined time, wherein the step (c) is performed according to a freezing point or ice point value set for the drying section.

14. The method for producing a dried product according to claim 13, further comprising, in addition to steps (a), (b) and (c), a step (d) of maintaining the internal temperature of the drying section within a third temperature range of 0°C or higher for a third predetermined period of time.

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