JP2023172117A - Fumigation method - Google Patents

Abstract

To provide a fumigation method which uses a gas having no problem even when applied to a processed food and does not cause dew condensation in a storage chamber.SOLUTION: The method includes: a step of storing food in an airtight storage; a depressurization step of reducing the pressure inside the storage; a carbon dioxide injection step of injecting carbon dioxide into the inside of the storage; an internal heating step of heating the inside of the storage to a preset high temperature; and a leaving step of starting a fumigation state with the inside of the storage at the preset high temperature and at a reduced pressure than atmospheric pressure, and maintaining the fumigation state for a certain period of time, and the method further adopts means for keeping the inside of the storage free of condensation for the certain period of time.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fumigation method and apparatus, and more particularly, to a technique for preventing quality deterioration due to condensation when fumigating processed foods.

Conventionally, the methods used to exterminate pests include atmospheric fumigation by reducing and pressurizing with carbon dioxide gas, vacuum fumigation with organic phosphorus and other insecticides, and atmospheric fumigation with hydrogen phosphide gas. It was getting worse. However, when organic phosphorus agents or hydrogen phosphide gas are used in processed foods, toxic substances remain, which is a problem.
Further, when fumigating processed foods such as pasta, there is a problem in that if dew condenses during the fumigation, the quality of the product deteriorates.
Therefore, there has been a need for a fumigation method that uses a gas that is suitable for processed foods and does not cause condensation inside the storage.

In this technical field, various techniques have been proposed in the past. For example, a method for killing insect pests on relatively soft agricultural products such as growing plants (see Patent Document 1) has been proposed and has become a publicly known technique. More specifically, the pressure inside the storage chamber containing plants, etc. is reduced, carbon dioxide is injected, and then the pressure inside the storage chamber is restored to the original pressure to increase the concentration of carbon dioxide to 40% by volume or more and 60% by volume. This is a method of exterminating pests by repeating the process several times to reduce the volume to below %.
However, there is a possibility that dew condensation may occur during depressurization, and this problem has not been solved.

Patent No. 6194212

In view of the problem that the quality of processed foods deteriorates due to dew condensation during fumigation, the present invention uses harmless carbon dioxide to fumigate at high temperatures and in a reduced pressure environment, thereby causing dew condensation inside the storage. It is an object of the present invention to provide a fumigation method and device that prevents fumigation.

In order to solve the above problems, the fumigation method according to the present invention includes a step of storing foodstuffs in an airtight storage container, a depressurization step of reducing the pressure inside the storage container, and a step of decompressing the inside of the storage container. A carbon dioxide injection step to inject carbon, an interior heating step to heat the inside of the storage chamber, and a fumigation state in which the inside of the storage chamber is at a preset high temperature and the pressure is lower than atmospheric pressure. and a leaving step of maintaining the fumigated state for a certain period of time, and means to keep the inside of the storage warehouse free of condensation for the certain period of time.

Further, the present invention employs means including a recovery step of recovering carbon dioxide in the storage chamber after fumigation.

Furthermore, the present invention employs a method in which the concentration of carbon dioxide is 80% or more.

Still further, the present invention employs means in which the preset high temperature is 38°C±3°C.

Furthermore, in the present invention, the inside heating step employs means for heating the inside of the housing by heat exchange with hot water.

Furthermore, in the present invention, the interior heating step employs a means of heating the inside of the housing by injecting high temperature carbon dioxide.

Furthermore, the present invention employs means that includes a moisture removal step for removing moisture contained in the injected carbon dioxide.

Furthermore, the fumigation apparatus according to the present invention includes an airtight storage for storing foodstuffs, a decompression section for reducing the pressure inside the storage, and a carbon dioxide injection section for injecting carbon dioxide into the storage. , an internal heating section that heats the storage chamber so that the temperature inside the storage chamber reaches a preset high temperature; and take measures to maintain fumigation conditions for a certain period of time.

According to the fumigation method and device of the present invention, no gas harmful to food is used and no condensation occurs during fumigation, so effective fumigation can be achieved without degrading the quality of the product. It can be carried out.

1 is an overall view showing an embodiment of a fumigation method according to the present invention; FIG. 1 is a process diagram showing an embodiment of a fumigation method according to the present invention. 1 is a schematic diagram of steps showing an embodiment of a fumigation method according to the present invention. FIG. It is a graph which shows the relationship between the temperature inside a storage warehouse and dew point temperature in the fumigation method according to the present invention.

The fumigation method and apparatus according to the present invention have the greatest feature that processed foods can be fumigated without causing dew condensation.
Embodiments of the fumigation method and apparatus according to the present invention will be described below based on the drawings.
Note that the overall shape and the shape of each part of the fumigation method and device shown below are not limited to the embodiments described below, but are within the scope of the technical idea of the present invention, that is, exhibiting the same effects. The shape, dimensions, structure, etc. can be changed as appropriate within the range of possible changes.

The present invention will be explained according to FIGS. 1 to 4.
FIG. 1 is an overall diagram of the present invention. FIG. 2 is a diagram showing the process flow of the present invention. FIG. 3 is a diagram showing the movement of each step of the present invention in order from (a) to (e). FIG. 4 is a graph showing the relationship between the internal storage temperature and the dew point temperature of the present invention, in which (a) shows the conventional example and (b) shows the present invention.
The fumigation device 1 kills pests on the surface and inside of processed foods by exposing them to high concentration carbon dioxide. Pests are killed not by suffocation by carbon dioxide, but by modulation of aerobic energy metabolism.
Processed foods are mainly imported foods such as pasta, organic products that do not use pesticides, and flours such as wheat flour, buckwheat flour, and rice flour.
The fumigation device 1 includes a storage chamber 10, a decompression section 20, a carbon dioxide injection section 30, a moisture removal section 40, an internal heating section 50 (51), a recovery section 60, and a control section 70.

The storage 10 is a housing for accommodating food products S to be fumigated. It has an opening/closing door to put food, etc. in and out. It has airtightness and is strong enough to withstand decompression.
The storage 10 is provided with an air outlet 11 for discharging internal air when the pressure is reduced. Further, a carbon dioxide injection port 12 for injecting carbon dioxide into the storage 10 is provided. Further, a carbon dioxide recovery port 13 is provided for recovering used carbon dioxide after fumigation for recycling.
During fumigation, the storage 10 may be left alone without being controlled or operated, or the temperature may be controlled. At least at the start of fumigation, the temperature inside the containment chamber 10 is set at about 38° C. to promote the activation and metabolism of pests, thereby increasing the fumigation effect of carbon dioxide.
At this time, if the temperature is much higher than 38°C, the processed food such as pasta itself may deteriorate, so a temperature of around 38°C is appropriate.
Assuming that the range of temperatures that occur on a daily basis is, for example, about 10% of 38°C, an appropriate temperature range is 38°C±3°C.

Further, the storage 10 may be provided with a fan that stirs the atmosphere within the storage 10. By stirring the carbon dioxide injected into the storage 10 and the depressurized air inside the storage 10, the atmosphere inside the storage 10 becomes uniform, and the insecticide is evenly applied to the entire food product S inside the storage 10. can give an effect.

The pressure reducing part 20 is a part that reduces the pressure in the storage chamber 10 by discharging the air to the outside. It is equipped with a vacuum pump 21 and a pressure reduction opening/closing valve 22. The pressure reduction opening/closing valve 22 is opened only during the period when the pressure reduction operation is performed. During other periods, the pressure reducing on-off valve 22 is closed. Control is performed by the control section 70. The vacuum pump 21 sucks out the air inside the storage 10 and has high suction power.
The vacuum pump 21 may be a steam ejector type pump, a general water ring type (water ring), or a combination of both.
The pressure inside the storage chamber 10 is reduced from the atmospheric pressure of 760 torr to a maximum of 0.0 torr. For example, the pressure is reduced to about several tens of torr. The inside of the storage 10 becomes almost a vacuum. Since the moisture is discharged outside the refrigerator together with the air, the amount of water vapor inside the refrigerator becomes extremely small.

The carbon dioxide injection unit 30 is a part that injects carbon dioxide into the storage 10, and includes an injection opening/closing valve 31 and a carbon dioxide cylinder 32. The injection on-off valve 31 is opened when injecting carbon dioxide, and is closed during other steps. Control is performed by a control section 70. The carbon dioxide cylinder 32 is a supply source of carbon dioxide gas and is kept in a liquid state. During injection, the carbon dioxide is appropriately vaporized using a vaporizer, gas sampling, etc. attached to the carbon dioxide cylinder 32.
Carbon dioxide in the carbon dioxide cylinder 32 is injected from the carbon dioxide inlet 12 of the storage 10 through the injection opening/closing valve 31 . During the injection process, carbon dioxide passes through the moisture removal section 40 and the internal heating section A50.
Carbon dioxide has a high concentration of 80% or more, and the pressure inside the chamber after injection is lower than the atmospheric pressure of 760 torr. For example, it is about 700 torr. Under these conditions, since the food is under reduced pressure and carbon dioxide is at a high concentration, carbon dioxide can permeate into the food products, resulting in a high fumigation effect.

The moisture removal section 40 is a portion that removes moisture from carbon dioxide. Depending on the type of carbon dioxide, the gas may contain moisture. Therefore, it is effective to remove the moisture in the carbon dioxide before injection.
The moisture removal section 40 is a section that removes water vapor contained in carbon dioxide gas, a so-called drying section.
By drying the carbon dioxide gas injected into the storage chamber 10, the amount of water vapor in the gas is reduced, and the amount of water vapor in the entire storage chamber 10 during fumigation can also be reduced. Therefore, the dew point temperature, which is the temperature at which dew condensation occurs inside the housing 10, can be lowered.
Drying methods include heating carbon dioxide to a high temperature, adsorbing water vapor with a filter membrane, changing the temperature and pressure of the gas to below the dew point, converting the water vapor into water droplets, and draining the water vapor through the water outlet 41 (drain trap). There are ways to discharge it.
When using a method of heating carbon dioxide to a high temperature, it can also be used as the internal heating part A50 by making adjustments.

The internal heating section A50 is a section that adds heat to carbon dioxide to make it high temperature. By increasing the temperature of the carbon dioxide to be injected, the temperature inside the storage chamber 10 during fumigation can be increased.
By increasing the fumigation temperature, the fumigation time can be shortened. For example, it has been confirmed that a 24-hour treatment has an insecticidal effect on two-spotted spider mites under conditions where the concentration of carbon dioxide is 50% or more and the temperature of the atmosphere is 25° C. or more.
Heating can be done by directly heating carbon dioxide with a heater or the like, or by using heat from a high-temperature medium using a heat exchanger.
The heating amount of carbon dioxide is set so that the temperature inside the storage chamber 10 becomes around 38° C. at the start of fumigation. The amount of heating varies depending on the volume of the storage 10, the amount of carbon dioxide to be injected, etc., and is therefore determined by prior measurement.

Instead of or simultaneously with the internal heating unit A50, the internal heating unit B51 can be used to heat the inside of the storage 10.
The internal heating unit B51 adopts a structure in which, for example, a tank filled with hot water at several tens of degrees Celsius is placed outside the refrigerator, and a hose through which the hot water from the tank is passed is coiled and circulated inside the storage 10. Thereby, the heat of the hot water is transmitted to the inside of the storage via the hose, and the inside of the storage 10 can be heated.

A plurality of (for example, four) temperature sensors are arranged in the storage 10. This allows the temperature at multiple locations to be checked at the same time, so it is possible to appropriately control the temperature in the refrigerator to make it uniform.

The recovery unit 60 is a part that recovers used carbon dioxide after completion of fumigation and stores it in the carbon dioxide cylinder 32 or the like. It is equipped with a pump 61 and a recovery opening/closing valve 62. The recovery on-off valve 62 is opened when recovering carbon dioxide, and is closed during other processes. Control is performed by a control section 70. The pump 61 sucks carbon dioxide in the storage 10 through the carbon dioxide recovery port 13 and returns it to the carbon dioxide cylinder 32. Liquefaction of carbon dioxide is performed, for example, by treatment at high pressure and low temperature.
Since the carbon dioxide that is inhaled may contain other gases, air, and water vapor generated during fumigation, it is also possible to remove the carbon dioxide with a filter or the like as necessary.
Since carbon dioxide can be recycled by the recovery unit 60, the device can be environmentally friendly.

The control unit 70 is a part that controls the entire device. The valves control the opening and closing of the depressurization on-off valve 22, the injection on-off valve 31, and the recovery on-off valve 62, and the sensors read the values of the pressure sensor 71, concentration sensor 72, and temperature sensor 73, and respond according to the values. Take control. Sensor values are checked and valves, etc. are controlled for each process: depressurization process, carbon dioxide injection process, moisture removal process, interior heating process, leaving process, and recovery process. For stand-alone processes, it is also possible to notify the completion of the fumigation period.

Explain the difference between fumigation of processed foods such as pasta and flour products and other types of fumigation.
Atmospheric pressure fumigation, in which carbon dioxide is used to fumigate agricultural products under normal pressure, is known. Since carbon dioxide is not toxic, it can be used for general agricultural products. However, with this method, fumigation took about 10 days and was not efficient. Additionally, during fumigation, the temperature inside the warehouse sometimes became low, resulting in condensation. Although condensation has little effect on agricultural products, this method was inappropriate for processed foods such as pasta because if the surface becomes wet due to condensation, the quality will be significantly reduced.

In addition, in the field of cultural properties, there is a method of vacuum fumigation using insecticides such as organic phosphorus agents and ethylene oxide. Processed foods such as pasta are unsuitable due to their toxicity.
Additionally, for foods that are subject to processing, there is a fumigation method using hydrogen phosphide gas. However, because it is harmful, explosive, and treated as a pesticide, it is difficult to apply it to processed foods such as pasta and organic products.

The fumigation method of the present invention is a fumigation method that can be applied to pasta-based and flour processed foods, imported foods, and organic products.
Fumigation is performed under reduced pressure using harmless carbon dioxide gas at a temperature of around 38°C. By using harmless carbon dioxide gas, it can be used in processed foods.
Additionally, by fumigating under reduced pressure, carbon dioxide can penetrate into the food, reducing the fumigation time. Furthermore, high-temperature fumigation activates pests and promotes their metabolism, making it possible to kill insects efficiently.
Furthermore, by drying the carbon dioxide gas, condensation can be prevented and the quality of processed foods such as pasta can be maintained.
As described above, the present invention provides a fumigation method suitable for processed foods such as pasta by appropriately setting dry carbon dioxide gas, pressure, and temperature.

The flow of the fumigation method will be explained with reference to FIGS. 2 and 3.
Food products S to be fumigated are stored in the storage 10 (S101, FIG. 3(a)). The control unit 70 closes the depressurization on-off valve 22, the injection on-off valve 31, and the recovery on-off valve 62.
Food products S are assumed to be processed foods, but other foods and crops may be used. However, it is not suitable for foods and crops that are damaged by reduced pressure.

(Decompression process)
The pressure inside the storage 10 is reduced (S102, FIG. 3(b)). The control unit 70 opens the pressure reduction on-off valve 22 and starts the vacuum pump 21. The vacuum pump 21 sucks out the air in the storage 10 through the air outlet 11 and discharges it from the vacuum pump 21 . For example, the pressure is reduced to about several tens of torr. Since 1 atmosphere is about 760 torr, the amount of air and water vapor inside the storage chamber 10 is extremely small.
The control unit 70 confirms that the pressure inside the storage chamber 10 has reached a predetermined pressure based on the value of the pressure sensor 71, stops the vacuum pump 21, and closes the depressurization opening/closing valve 22.

(Carbon dioxide injection process)
Carbon dioxide is injected into the storage 10 (S103, FIG. 3(c)). The control unit 70 opens the injection opening/closing valve 31 and injects the carbon dioxide in the carbon dioxide cylinder 32 into the storage 10 through the carbon dioxide injection port 12 .
The amount of carbon dioxide to be injected is an amount that can exhibit the effect of carbon dioxide while maintaining the effect of reducing the pressure inside the storage chamber 10.
During the injection process, the moisture removal section 40 and the internal heating section A50 remove moisture from the carbon dioxide and heat the carbon dioxide.
When carbon dioxide is injected into the storage chamber 10 and the pressure sensor 71, concentration sensor 72, and temperature sensor 73 reach predetermined values, the control unit 70 closes the injection on-off valve 31 and stops the injection of carbon dioxide. .

(Moisture removal process)
The moisture in the carbon dioxide to be injected is removed (S104, FIG. 3(c)). By drying the carbon dioxide, the moisture in the carbon dioxide is removed. In other words, it reduces the amount of water vapor in carbon dioxide. By reducing the amount of water vapor, the dew point temperature of the atmosphere inside the storage warehouse 10 is lowered, and it is possible to avoid a state in which the foodstuffs S become dew-condensed.

(Internal heating process)
The temperature inside the refrigerator is raised using the internal heating part A50 or the internal heating part B51, or by using the internal heating part A50 and the internal heating part B51 at the same time (S105, FIG. 3(c)). By raising the temperature of carbon dioxide existing in the storage chamber to a high temperature, the temperature inside the storage chamber 10 during fumigation is increased and insect killing is promoted. Pests become active in high temperature conditions and their metabolism becomes active. The effect of carbon dioxide can be improved accordingly.
The temperature of carbon dioxide is set so that the temperature inside the storage chamber 10 is around 38°C.

(Leave process)
After completing the depressurization of the storage chamber 10 and the injection of carbon dioxide, fumigation is performed (S106, FIG. 3(d)). During fumigation, the depressurization on-off valve 22, the injection on-off valve 31, and the recovery on-off valve 62 are closed, and the left state continues.
The food product S is continuously covered with a suitable concentration of carbon dioxide at a high temperature. Since the food product S is in a reduced pressure state, carbon dioxide is appropriately absorbed into the food product S, and pests inside can be killed in a short time.
Although the fumigation time varies depending on the food product S, it is, for example, about 40 hours, considering the time it takes for pests to die. After the fumigation time has elapsed, the control unit 70 may notify that the fumigation time has elapsed.
During fumigation, the temperature inside the refrigerator may be controlled by the internal heating section B51, or the temperature management may be stopped. In any case, after the completion of fumigation, there may be a period of up to two days in which the temperature is not controlled. It is important that the temperature does not get too high, that is, that no condensation forms inside the refrigerator.

(Collection process)
Carbon dioxide in the storage 10 is recovered for recycling (S107, FIG. 3(e)).
Carbon dioxide after fumigation is unnecessary, but it can be recovered and reused. Carbon dioxide in the storage 10 is stored in the carbon dioxide cylinder 32 via the carbon dioxide recovery port 13.
The control unit 70 opens the recovery on-off valve 62 and drives the pump 61 to recover carbon dioxide. Impurities contained in carbon dioxide may be removed using a filter or the like.
After the collection is completed, the food items S in the storage warehouse 10 are taken out and the process is completed (S108).

The relationship between the storage chamber internal temperature and dew point temperature in the conventional case and in this embodiment will be explained along FIG. 4. This explanation assumes that the temperature inside the refrigerator is controlled only at the start of fumigation. If temperature control was carried out during fumigation, the time point "fumigation started" in the diagram should be read as the "completion of fumigation" time, and the time point "completion of fumigation" should be read as "the time when food products were removed from the warehouse". It can be read as the point in time.

FIG. 4A shows a case where the carbon dioxide is not dried and the temperature inside the storage chamber 10 is about 20° C., which is room temperature. At the start of fumigation, the temperature inside the storage chamber 10 is about 20° C., which is room temperature. Thereafter, the temperature inside the storage 10 changes depending on the outside air temperature.
The dew point temperature at which the amount of water vapor inside the storage room 10 reaches the saturated amount of water vapor is approximately the same as the temperature outside the storage room 10. On winter nights, etc., the inside of the storage room 10 also reaches the dew point temperature, and the food inside the storage room 10 Dew gets on the product S, causing deterioration in the quality of products such as pasta.

FIG. 4(b) shows the case of this embodiment. Carbon dioxide is dry, and the temperature inside the storage chamber 10 is as high as about 38°C. At the start of fumigation, the temperature inside the storage chamber 10 is 38°C. Thereafter, the temperature inside the storage chamber 10 changes depending on the outside air temperature, but since the initial temperature is high, the temperature as a whole takes a higher value than in the conventional case.
Further, the amount of water vapor in the storage 10 is extremely low because the carbon dioxide is dry, and the dew point temperature is lower than in the conventional case.
Therefore, since the temperature inside the housing 10 is higher and the dew point temperature is lower than in the past, the possibility of occurrence of dew condensation is extremely low.

As described above, according to the present embodiment, since no gas harmful to food is used and no condensation occurs during fumigation, effective fumigation can be performed without degrading the quality of the product. be able to.

It is understood that the fumigation method according to the present invention has great industrial applicability as a technology for performing fumigation while maintaining the quality of processed foods such as pasta.

1 Fumigation device 10 Containment chamber 11 Air outlet 12 Carbon dioxide inlet 13 Carbon dioxide recovery port 20 Pressure reduction section 21 Vacuum pump 22 Pressure reduction opening/closing valve 30 Carbon dioxide injection section 31 Injection opening/closing valve 32 Carbon dioxide cylinder 40 Moisture removal section 41 Moisture outlet 50 Internal heating section A
51 Internal heating section B
60 Recovery section 61 Pump 62 Recovery on/off valve 70 Control section 71 Pressure sensor 72 Concentration sensor 73 Temperature sensor S Food products

The present invention relates to a fumigation method , and more particularly, to a technique for preventing quality deterioration due to condensation when fumigating processed foods.

In view of the problem that the quality of processed foods deteriorates due to dew condensation during fumigation, the present invention uses harmless carbon dioxide to fumigate at high temperatures and in a reduced pressure environment, thereby causing dew condensation inside the storage. The objective is to provide a fumigation method that does not cause

According to the fumigation method of the present invention, no gas harmful to food is used and no condensation occurs during fumigation, so effective fumigation can be performed without degrading the quality of the product. be able to.

The biggest feature of the fumigation method according to the present invention is that processed foods can be fumigated without causing dew condensation.
Hereinafter, embodiments of the fumigation method according to the present invention will be described based on the drawings.
Note that the overall shape and the shape of each part of the fumigation method shown below are not limited to the embodiments described below, and are within the scope of the technical idea of the present invention, that is, can exhibit the same effects. The shape, dimensions, structure, etc. can be changed as appropriate within the range.

Claims (8)

A method for fumigating foodstuffs, the method comprising:
a step of storing food products in an airtight storage;
a depressurization step of decompressing the inside of the storage;
a carbon dioxide injection step of injecting carbon dioxide into the storage;
an internal heating step of heating the inside of the storage to a preset high temperature;
A leaving step of starting a fumigation state with the inside of the storage chamber at a preset high temperature and a pressure lower than atmospheric pressure, and maintaining the fumigation state for a certain period of time,
A fumigation method characterized in that the inside of the storage is kept free from condensation for the certain period of time. 2. The fumigation method according to claim 1, further comprising a recovery step of recovering carbon dioxide in the storage chamber after fumigation. The fumigation method according to claim 1, wherein the concentration of carbon dioxide is 80% or more. The fumigation method according to claim 1, wherein the preset high temperature is 38°C±3°C. 2. The fumigation method according to claim 1, wherein the interior heating step heats the inside of the storage chamber by heat exchange with hot water. 2. The fumigation method according to claim 1, wherein in the heating step, the inside of the storage chamber is heated by injecting carbon dioxide at a high temperature. 7. The fumigation method according to claim 1, further comprising a moisture removal step of removing moisture contained in the injected carbon dioxide. an airtight storage for storing food;
a decompression unit that depressurizes the inside of the storage;
a carbon dioxide injection unit that injects carbon dioxide into the storage;
an internal heating unit that heats the storage compartment to a preset high temperature;
A fumigation device characterized in that a fumigation state is started when the inside of the storage chamber is at a preset high temperature and a pressure lower than atmospheric pressure, and the fumigation state is maintained for a certain period of time.