JP5687745B1 - Drying method for freeze-dried product and freeze-drying apparatus - Google Patents

Abstract

An object of the present invention is to provide a method for drying an object to be dried in freeze-drying and a freeze-drying apparatus for the completion of drying. A frozen object to be dried 1 is frozen after being mounted in a container 2 having high radiation heat absorption ability by a far-infrared heater 12 and good thermal conductivity, and a plurality of containers are mounted in a decompression tank 6. After reducing the pressure in the decompression tank to a pressure at which sublimation occurs in the object to be dried, the container on which the object is dried is heated by a far-infrared heater to cause heat conduction from the container to the object to be dried and sublimate to the object to be dried. The temperature of the surface of the container is measured by the thermocouple 3 under the pressure of the decompression tank that generates and dries, and the temperature setting of the container surface temperature is 30 degrees Celsius at which no component destruction occurs according to the type of the object to be dried. A method for drying an object to be dried in lyophilization, wherein the drying step is completed by returning the reduced pressure state to atmospheric pressure when a designated temperature in a range of from 90 degrees Celsius to 90 degrees Celsius is reached. [Selection] Figure 1

Description

The present invention, vegetables, seafood, fruits, the material to be dried in any one of the food in processed food can be a short time to efficiently freeze-dried, frozen to achieve a uniform quality of the dried product The present invention relates to a method for drying an object to be dried and its freeze-drying apparatus.

  In conventional typical freeze-drying, in order to heat the material to be dried, each container carrying the material to be dried is directly heated from a very short distance by a sheath heater. Usually, the mechanism is such that the object to be dried in the vicinity is dried, and the object to be dried away from the line heater is dried by obtaining heat conduction from the object to be dried in the vicinity of the sheathed heater.

  With this method, it is necessary to install a large number of seed heaters corresponding to the large number of trays on which the objects to be dried are mounted. There was a drawback of becoming expensive.

  Moreover, since the drying level is different between the object to be dried in the vicinity of the sheathed heater and the object to be dried away from the sheathed heater, it took a very long time to unify them. In other words, the temperature of the object to be dried in the vicinity of the sheath heater after the middle of the drying process is different from the temperature of the object to be dried away from the sheath heater, and the temperature varies widely. In order to achieve this, a very weak heat source is used, in which drying of the object to be dried away from the sheath heater is standard, and the drying heat source relies on heat conduction from the object to be dried close to the sheath heater. Therefore, it took a long time of 24 to 36 hours for drying.

  Also, in the conventional freeze-drying, when drying is finished, representatively extract a plurality of temperatures of the object to be dried and measure the temperature, and the drying is finished when the object to be dried reaches a predetermined temperature. Or, the end of drying was determined by time based on empirical rules. However, in conventional freeze-drying, the dryness, that is, the moisture contained in the material to be dried varies depending on the position of the material to be dried. In addition, work must be done to identify the positional relationship of these samples with respect to the seed heater, and since the temperature varies depending on the position of the object to be dried, high accuracy of termination control by temperature measurement is promised. Was difficult.

  At the same time, the object to be dried located near the sheathed heater previously dried is exposed to heat for a long time to conduct heat to the object to be dried away from the sheathed heater. In the case of drying, the quality of the material to be dried, that is, the result of significantly reducing the taste, aroma, color, nutritional value, etc. often occurred.

In addition, among the heating technologies for the object to be dried to compensate for the disadvantages of the lyophilization technique using the conventional wire heater as described above, an oil pan or hot water pan is provided under the container to be dried. In technology that freezes and dries by heating a dry matter-carrying container, it is necessary to supply heated oil and hot water to each of the dry matter-carrying containers that are installed in the device. Not only is it expensive , but it is very difficult to control the temperature of heated oil or hot water, so it is difficult to perform good quality drying.

  On the other hand, it was possible to use a surface heater to heat the container to be dried instead of the line heater, but this led to great complexity of the apparatus and high cost of the apparatus.

  In the freeze-drying according to the invention of the heating technology for a container to be dried having a high far-infrared absorption capacity by a far-infrared heater provided in a vacuum chamber, which is the background of the technology, at the end of drying, the far-infrared absorption capacity is high. Since the temperature of the dry matter mounting container and the temperature of the dry matter are approximate or equivalent, the drying can be finished with high accuracy by measuring the temperature of the dry matter mounting container.

  In addition, it is possible to provide radiation heat from the far-infrared heater to each of a plurality of containers to be dried having a high absorption capacity for far-infrared rays, so that the entire container can be efficiently heated. It can be performed.

  As a conventional freeze-drying method of food, after freezing a brick product containing fish surimi, the pressure during drying is set to 0.6 to 0.65 torr for the brick product, After performing primary sublimation which is dried for 1.5 to 2.5 hours in an environment, second sublimation is performed for 14 to 16 hours in an environment of 70 to 80 ° C., and an environment of 45 to 55 ° C. A time-based control method characterized by performing third sublimation in which drying is performed for 23 to 25 hours is disclosed (Japanese Patent Laid-Open No. 2007-167014).

JP 2007-167014 A

  In the above invention of the conventional freeze-drying method, control by time is disclosed, but the drying time varies depending on the size, number, etc. of the material to be dried. It is impossible to obtain high drying termination control.

  In addition, there is a method to measure the temperature of the object to be dried by inserting a thermocouple etc. into the object to be dried, but due to the variation in drying depending on the position of the object to be dried in conventional freeze-drying, highly accurate drying is completed. You cannot get control.

  An object of the present invention is to provide a method for drying an object to be dried in freeze-drying that accurately detects the end of drying regardless of the amount and type of the object to be dried, and a freeze-drying apparatus thereof.

The present invention is a method for drying an object to be dried in freeze-drying, wherein the object to be dried is any one of frozen vegetables, seafood, fruits and processed foods, which has a high ability to absorb radiant heat by a far-infrared heater and is heated. after the conductivity frozen after mounting the good multiple containers were the plurality of containers to reduce the pressure in the vacuum tank mounted at intervals in multiple stages in vacuum tank pressure sublimation occurs material to be dried, heating the material to be dried equipped container by the far infrared heater, causing a heat conduction material to be dried from the vessel, under pressure of the vacuum tank for drying caused the sublimation material to be dried, a plurality of material to be dried equipped container The temperature received from a small plate for temperature detection, which is the same material and the same material as the container to be dried installed in the center of the bottom, is detected from multiple locations with thermocouples or infrared thermometers. Destruction of ingredients In occurs no temperature, and a method for drying objects to be dried in the freeze-drying and performing complete control the drying when the temperature measured at a plurality of locations is matched with the temperature control unit according to PID.

Freeze-drying apparatus, at a reduced pressure tank which was installed far infrared heater for irradiating the outer peripheral surface of the material to be dried equipped vessel, the intervals over vertical transport to the vacuum vessel to be used for freeze-drying method according to claim 1, wherein a container carrier that is installed in multiple stages, the material to be dried equipped container absorption capacity is high and the thermal conductivity of the plurality good radiant heat to be mounted at intervals in multiple stages in the container carrier, said each material to be dried equipped container It has a control unit for sublimating the dried product under the reduced pressure condition in which the dried product in the decompression tank is sublimated, and the dried product to be stored is one of frozen vegetables, seafood, fruits and processed foods to be stored. Place the same material and the same surface-treated small temperature detection plate in the bottom center of the dry matter loading container in different containers, and the temperature received by the small plates in the multiple places Complete the drying by matching Characterized by comprising a temperature control unit according to PID to be.

As a basic matter of the freeze-drying method according to the present invention, in the freeze-drying, the to-be-dried object mounting container having a high far-infrared absorption ability continuously receives the temperature-controlled far-infrared radiant heat, from the to-be-dried object mounting container. Drying is carried out by generating heat conduction in the mounted object to be dried, and the end of the object to be dried is detected by a temperature detector using a thermocouple or infrared thermometer, so that component destruction does not occur depending on the type of object to be dried. You can get things. That is, the temperature received from a small plate for temperature detection, which is the same material and the same surface treatment as that of the container to be dried installed in the center of the bottom of the plurality of containers to be dried, is measured by a thermocouple or an infrared thermometer. Control that completes drying when the temperature detected from the location does not cause the component destruction of the material to be dried and the temperatures coincide at the plurality of locations can be performed by the temperature adjustment control unit using PID.

  In the freeze-drying of the present invention, when the drying is completed, the temperature of the container to be dried and the temperature of the object to be dried are close to or equal to each other, and the ice content of the object to be dried has been sublimated. Therefore, the temperature of the object to be dried has risen to a temperature that is close to or equivalent to that of the container on which the object is to be dried, i.e., the drying has been completed. Therefore, optimum temperature control can be realized, and uniform products to be dried can be mass-produced.

  With the freeze-drying method of the present invention, it is sufficient to measure the temperature of the container to be dried, so that even if the dry loading amount changes, it is freed from inaccurate control by time control.

  In addition, conventionally, when measuring the temperature of an object to be dried, the temperature of the object to be dried varies depending on the position of the object to be dried. In the present invention, the temperature measurement of the object-to-be-dried container detects the heat obtained from the thermocouple or the infrared thermometer, and at the same time accurately reflects the temperature transmitted from the temperature of the entire object to be dried, The completion of drying can be detected with high accuracy.

  According to the present invention, since completion of lyophilization can be accurately known, it is not necessary to set an extra drying time in lyophilization as in the prior art, and production efficiency is improved.

  The freeze-drying method according to the present invention includes a plurality of far-infrared heaters in a vacuum chamber, a to-be-dried object mounting container having a high far-infrared absorption capability, and a far-infrared heater at a pressure at which sublimation occurs in the to-be-dried object. This is a mechanism in which the radiant heat is absorbed by the object-to-be-dried container, and then the heat of the object-to-be-dried object container is conducted to the object to be dried to cause sublimation of the object to be dried and dried.

  Since the equipment is extremely simple, the equipment cost is low, and the drying equipment-equipped container absorbs radiant heat from far infrared rays in the entire container, so the heating efficiency of the drying object is high, and the drying time is about half that of the conventional method. Drying can be completed, and the present invention achieves a significant increase in production volume by highly accurate end control. In addition, a plurality of far-infrared heaters that hang from the ceiling of the decompression tank at a predetermined interval are provided, and the radiant heat generated from the far-infrared heaters is installed in a plurality of temperature-controlled multiple far-infrared absorbing capacities. This is a freeze-drying method in which the dried product storage container is heated and heated by heat conduction from the dried product storage container to perform drying, and the drying can be finished with high accuracy. In addition, by installing the far infrared heater terminal outside the decompression tank, the far infrared heater terminal is safe and withstands long-term use without being affected by the environment of the decompression tank.

  As a basic matter, in freeze-drying according to the present invention, a dry matter mounting container having a high far-infrared absorption capacity continuously receives temperature-controlled far-infrared radiation heat, and the dry matter mounted from the dry matter mounting container Heat conduction is generated and drying can be promoted.

  When the drying is completed, the temperature of the object to be dried and the temperature of the object to be dried are close to or equal to each other. It indicates that the temperature has been raised to a temperature approximate to or equivalent to that of the container to be dried, that is, drying has been completed.

  According to the method of the present invention, the temperature of the container to be dried can be measured, so that even if the amount of dry load changes, the inaccurate control by time control is released.

  Further, when measuring the temperature of the object to be dried, the temperature of the object to be dried varies depending on the position of the object to be dried. Then, the temperature of the container to be dried is measured by detecting the heat obtained from the far-infrared heater with a thermocouple or infrared thermometer, and at the same time, accurately measuring the temperature transferred from the temperature of the entire object to be dried. Since this is reflected, the completion of drying can be detected with high accuracy.

It is a schematic explanatory drawing which shows the state which makes a thermocouple contact the bottom outer surface of the to-be-dried object mounting container with a high far-infrared absorptivity in the decompression tank which concerns on this invention, and measures temperature. It is a schematic explanatory drawing which shows the state which irradiates infrared rays to the bottom outer surface of the to-be-dried object mounting container with a high far-infrared absorptivity in the decompression tank which concerns on this invention, and measures temperature. It is a schematic explanatory drawing which shows the freeze-drying apparatus which concerns on this invention.

Embodiments of the present invention will be described below with reference to FIGS.
FIG. 1 is a schematic explanatory view showing a state in which a thermocouple is brought into contact with the bottom outer surface of a container to be dried having a high far-infrared absorption capacity in a decompression tank according to the present invention and the temperature is measured. 2 shows the to-be-dried object mounting container 2 with a high far-infrared absorptivity, and 1 shows a to-be-dried object. The to-be-dried object mounting container 2 is obtained by forming a coating film such as a black paint having a high far-infrared absorbing ability on the front and back surfaces of a metal container having good conductivity such as stainless steel. Reference numeral 5 denotes the inside of the decompression tank, 3 denotes a thermocouple, and the detection unit contacts the bottom outer surface of the object-to-be-dried object mounting container 2 and measures the temperature. The temperature is measured by connecting to a temperature detector 4 provided outside the decompression tank 6 of the thermocouple 3.

  FIG. 2 is a schematic explanatory view showing a state in which the temperature is measured by irradiating the bottom outer surface of the container to be dried with high far-infrared absorption capacity in the decompression tank according to the present invention with infrared rays. The schematic explanatory drawing which shows the state which irradiates the infrared rays 9 to the bottom part of the to-be-dried material mounting container 2, and measures temperature is shown. 2 shows the to-be-dried object mounting container 2 with a high far-infrared absorptivity, and 1 shows a to-be-dried object. Reference numeral 8 denotes an infrared thermometer, and reference numeral 4 denotes a state in which infrared light is irradiated to the bottom of the object-to-be-dried object mounting container 2 and temperature is measured. Reference numeral 10 denotes an infrared transmitting portion provided in the decompression tank 6, and quartz glass or the like is used. The infrared thermometer 8 is connected to a control unit 7 installed outside the decompression tank 6.

  FIG. 3 is a schematic explanatory view showing a freeze-drying apparatus according to the present invention. In the figure, 2 indicates a container to be dried and 1 indicates a substance to be dried. Reference numeral 11 denotes a container mounting shelf of the object to be dried mounting container 2. Reference numeral 3 denotes a temperature measurement unit such as a thermocouple, which is connected to the temperature detection unit 4 and the drying control unit 7 and controls the end of drying. Reference numeral 6 denotes a decompression tank, 13 denotes a cold trap that captures sublimation vapor generated from the decompression tank 6, and a refrigerator 14 is connected to the cold trap 13. In the figure, 15 is a vacuum pump.

  The base material of the container to be dried was formed into a box shape with an aluminum depth of 30 mm, and the container was painted with a black resin having a high far-infrared absorption capability by baking a silicon resin.

  The container was loaded with 1 kg of spinach frozen at −30 ° C., and 100 sheets of the container, that is, 100 kg of spinach, were mounted in a vacuum tank provided with a far infrared heater. Depressurization was started, and drying of the material to be dried was started. The pressure was stable at 0.5 torr. At this time, when 18 far-infrared heaters with an output of 1 kW per unit installed in the vacuum chamber were energized, sublimation from the material to be dried began to occur after 5 minutes, so the pressure rose to 2.5 torr and stabilized. did. In the temperature measurement with the thermocouple outside the container to be dried at the start of drying, the temperature was −30 ° C., which was the same as that of the object to be dried frozen by the thermal conduction from the object to be dried mounted on the container. In the temperature measurement after 12 hours at the same position, drying progressed and the temperature of the thermocouple was −5 ° C. Further, in the temperature measurement after 1 hour, the temperature started to rise and was -1 ° C. Further, after 1 hour, the temperature reached + 40 ° C. Experimentation has confirmed that the temperature of the material to be dried is similar to the temperature of the container to be dried, and by not heating the material to be dried at 45 ° C or higher, nutrients, color, taste, etc. Since it was confirmed by analysis that there was no damage, drying was terminated at this point, the pressure was returned to atmospheric pressure, and the material to be dried was taken up.

  Later analysis revealed that it was a dried spinach with nutrients, color and taste similar to the original ingredients.

1 kg of miso was loaded on 100 pieces of dry matter storage containers each having a high far-infrared absorption capacity, and frozen at −30 ° C. These were mounted in a vacuum chamber equipped with 18 heaters with a far-infrared output of 1 kW, and the temperature change of the dry matter mounting container was recorded. The far-infrared heater always heats the container to be dried at 45 ° C, and the heating control is performed at the same distance as the distance from the heater surface to the center of the bottom of the container to be dried. A 30 mm square plate with the same material and surface treatment as the mounting container was installed, and the temperature was adjusted by PID according to the temperature received by the plate.
The vacuum pressure changed between 2.3 torr and 2.8 torr.
In the end control, the temperature of the three points on the outer surface of the bottom of the container to be dried was measured with a thermocouple, and the drying was completed when all three points of the container to be dried showed + 40 ° C.
The temperature transition table is shown below.

  Each 100 kg of onion soup was loaded on 100 to-be-dried objects-loading containers having a high far-infrared absorptivity and frozen at −30 ° C. These were mounted in a vacuum chamber equipped with 18 heaters with a far-infrared output of 1 kW. The heating temperature of the heater to the container was controlled at 55 ° C., the temperature of the bottom outer surface of the container to be dried was measured with infrared rays, and the process was terminated when the temperature reached 50 ° C.

  The vacuum pressure changed at a pressure around 2.5 torr during the drying process.

  Drying was completed when the temperature outside the bottom surface of the object mounting container was measured with a thermocouple and the temperature reached 50 ° C. Twelve hours after the start of drying, the temperature outside the bottom surface of the container to be dried was 50 ° C., and thus drying was completed.

  The dried solid was collected and pulverized into powder. A powdery onion soup that is excellent in taste, aroma, and color and dissolves in hot water instantly when hot water is poured into it.

  The present invention is effective in all fields of food such as vegetables, seafood, fruits and processed foods, pharmaceutical fields such as pharmaceuticals, cosmetics fields, and other fields where lyophilization has been conventionally used. The lyophilization method and the lyophilization apparatus that can achieve lyophilization efficiently in a short time and achieve uniform quality of the material to be dried are used in a wide range of industrial fields.

DESCRIPTION OF SYMBOLS 1 To-be-dried object 2 To-be-dried object mounting container 3 Thermocouple 4 Temperature detection meter 5 Depressurization tank inside 6 Decompression tank 7 Drying control part 8 Infrared thermometer 9 Infrared 10 Infrared transmitting glass 11 Container mounting shelf 12 Far infrared heater 13 Cold trap 14 Refrigerator 15 Vacuum pump

Claims (2)

A drying method for freeze-dried products, which is one of frozen vegetables, seafood, fruits and processed foods, which has a high radiant heat absorption capability with a far-infrared heater and good thermal conductivity. such plurality of frozen after mounting to the container, the pressure in the vacuum vessel the plurality of containers mounted at intervals in multiple stages in vacuum vessel after pressure reduction to a pressure sublimation occurs material to be dried, the material to be dried heating the mounted container by the far infrared heater, causing a heat conduction material to be dried from the vessel, under pressure of the vacuum tank for drying caused the sublimation material to be dried, a bottom central portion of the plurality of objects to be dried equipped container The temperature of the material to be dried is the same as the container to be dried and the same surface treatment and the temperature received from a small plate for temperature detection is detected from multiple locations with thermocouples or infrared thermometers. Does not occur Drying method the object to be dried in freeze-dried, characterized in that every time in, and performs complete control the drying when the temperature measured at a plurality of locations is matched with the temperature control unit according to PID. Freeze-drying apparatus, at a reduced pressure tank which was installed far infrared heater for irradiating the outer peripheral surface of the material to be dried equipped vessel, the intervals over vertical transport to the vacuum vessel to be used for freeze-drying method according to claim 1, wherein a container carrier that is installed in multiple stages, the material to be dried equipped container absorption capacity is high and the thermal conductivity of the plurality good radiant heat to be mounted at intervals in multiple stages in the container carrier, said each material to be dried equipped container It has a control unit for sublimating the dried product under the reduced pressure condition in which the dried product in the decompression tank is sublimated, and the dried product to be stored is one of frozen vegetables, seafood, fruits and processed foods to be stored. Place the same material and the same surface-treated small temperature detection plate in the bottom center of the dry matter loading container in different containers, and the temperature received by the small plates in the multiple places Complete the drying by matching Freeze-drying apparatus of the object to be dried, characterized in that it comprises a temperature control unit according to PID to be.

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