KR101429715B1 - Apparatus for preserving agricultural products to maintain beneficial modified atmosphere in container by controlling opening/closing of vent hole through time-control, and method for preserving the same - Google Patents

Abstract

The present invention relates to an apparatus and a method for maintaining freshness of agricultural products through time-controlled ventilation of a storage container. The apparatus and method for maintaining the freshness of agricultural products through the time-controlled venting of the storage container according to the present invention can maintain the freshness of the agricultural products in an environmentally friendly and economical way in the distribution and storage of the agricultural products, It is effective.

Description

[0001] The present invention relates to an apparatus and method for maintaining freshness of agricultural products by opening and closing time-controlled vents of a storage container, and a method for preserving freshness of agricultural products,

The present invention relates to an apparatus and a method for maintaining freshness of agricultural products through time-controlled ventilation of a storage container.

Controlling temperature and humidity is most important to maintain freshness during transportation, storage and distribution of fruits and vegetables. It is generally known that it is desirable to keep the temperature as low as possible and the relative humidity as high as about 90% under the range avoiding the low-temperature disturbance. By controlling the composition of the gas around the agricultural products, the freshness of the agricultural products can be improved and the shelf life can be prolonged. It is well known that gas composition with reduced oxygen concentration and increased carbon dioxide concentration compared with atmospheric conditions has the function of retarding the softening and quality change of agricultural products by suppressing respiration and physiological action of agricultural products. Typically, the modified gas composition is in the range of 2 to 10% oxygen concentration and 3 to 15% carbon dioxide concentration, but the gas composition required for each item is different. Table 1 below shows the appropriate modified atmosphere (MA) generally known in the literature and industry for representative agricultural products. Proper MA conditions may vary slightly depending on the variety, cultivation conditions, etc., but it is understood that the recommended concentrations in Table 1 are applied universally. Even though these MA conditions are not precisely formulated, a lowered oxygen concentration and an increased carbon dioxide concentration close to it are perceived to help maintain the freshness of the produce. However, if the oxygen concentration is excessively low or the carbon dioxide concentration becomes too high as compared with the appropriate range, physiological disturbances such as odor generation, softening, browning, and tissue necrosis may occur.

subject Oxygen (%) carbon dioxide (%) feeling 3 to 5 5 to 8 carrot 5 3 to 4 Strawberry 4 to 10 15 to 20 banana 2 to 5 2 to 5 mushroom 1 to 3 10 to 15 peach 1 to 2 3 to 5 ship 2 to 3 0 to 1 broccoli 1 to 2 5 to 10 Blueberries 5 to 10 15 to 20 Apple 1 to 3 1 to 3 spinach 7 to 10 5 to 10 Fresh vegetables / fruits 3 to 10 3 to 10 cabbage 3 to 5 3 to 6 Orange 5 to 10 0 to 5 Cherry 3 to 10 10 to 15 grape 2 to 5 1 to 3 Green pepper 3 to 5 2 to 8

In order to maintain the MA of the proper composition, an automatic control device which generates carbon dioxide while removing oxygen from inside is used in the controlled atmosphere (CA) storage, and as a result, the CA storage device is installed and operated It costs a lot. As another method, in MA packaging, appropriate materials and conditions are selected in plastic film bag or container to maintain the proper MA condition inside by balancing the gas permeation of the agricultural product with the gas permeation of the packaging material. MA packaging has the advantage of forming MA at a relatively low cost, but there are limitations in obtaining accurate MA conditions because of the restriction on obtaining a film or a container material having gas permeability suitable for various items. Although the formation of MA in loose conditions in MA packaging is also helpful in preserving quality, in many cases the gas permeability of the plastic container material is not sufficiently high to form oxygen-depleted anaerobic conditions and the ratio of carbon dioxide permeation to oxygen permeation is typically 3 To < RTI ID = 0.0 > 7 < / RTI >

Recently, some methods have been used to install small ventilation holes or ventilation holes to overcome the limitation in obtaining proper MA composition in storage containers or packaging of agricultural products. The vent or vents also serve to increase gas permeability, but also have the function of expanding the range of MA conditions that can be obtained by adjusting the ratio of carbon dioxide permeation to oxygen permeation to 1. The vent or vents used may be as small as 20 to 300 μm in a packaging film or sheet, but in a large container system, tubes or channels having a certain length (typically 0.1 to 15 cm) and a diameter of 0.1 to 2 cm do. However, there is a limit to the gas composition that can be obtained by the size and diameter of the vents, so that the conditions of containers and packages manufactured under one condition can not be applied to various items or temperature conditions. As a method to overcome this, it is possible to maintain the gas composition close to the comparatively preferable MA condition by appropriately controlling the opening and closing time of the ventilation hole in the condition of the ventilation hole having a relatively general purpose.

In the packaging or containers of agricultural products, oxygen is consumed and carbon dioxide is produced by the respiration of agricultural products. As a result, carbon dioxide accumulates inside and oxygen concentration decreases. Depending on the oxygen and carbon dioxide permeability of the package or container, the amount of carbon dioxide accumulated inside and the amount of oxygen that is reduced will be affected. In many cases, however, the gas permeability of the packaging or container is insufficient, resulting in depletion of oxygen to 0%, and the concentration of carbon dioxide reaches 20% or more, causing physiological disturbance to the agricultural products and deteriorating the color and flavor. Especially, depletion of oxygen induces anaerobic metabolism, causing various odor including alcohol odor, resulting in serious quality loss. However, if a ventilation hole is provided in a package or a container and it is opened at an appropriate time interval, oxygen from the outside flows into the inside through the ventilation hole, and the inside of the carbon dioxide flows out to the outside. Therefore, if the air vents are repeatedly closed and opened at regular intervals, the oxygen concentration of the vessel is not excessively lowered and the concentration of carbon dioxide is not excessively increased. That is, in the open condition of the vent hole, the gas movement to the outside becomes high, thereby preventing the exhaustion of oxygen and preventing or mitigating the excessive increase of the carbon dioxide concentration. However, if the opening time is too long, the internal gas deformation is insignificant due to a large amount of gas movement between the inside and the outside, so that MA that helps maintain the quality is not formed. Therefore, it is necessary to adjust the opening and closing time of the ventilation at appropriate time or rate to maintain proper oxygen concentration and carbon dioxide concentration to help preserve quality. It is possible to maintain the vicinity of the MA composition range which is optimum for preserving the quality of the agricultural product item by appropriately controlling the ratio of the opening time of the vent. However, there is little research on efficient and inexpensive agricultural product freshness maintenance apparatus and method that can solve the above problems.

The inventors of the present invention confirmed that the freshness of agricultural products can be maintained by appropriately modifying the composition of the internal gas by controlling the opening and closing of the ventilation with a temporal control program while searching for an efficient and inexpensive agricultural product storage apparatus.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an apparatus for maintaining the freshness of agricultural products through time-controlled ventilation opening / closing of a storage container.

It is another object of the present invention to provide a method of maintaining the freshness of agricultural products through time-controlled ventilation opening / closing of the storage container.

The present invention provides an apparatus for maintaining freshness of agricultural products through time-controlled ventilation opening and closing of a storage container.

The present invention also provides a method of maintaining the freshness of agricultural products by opening and closing the time controlled vents of the storage container.

The apparatus and method for maintaining the freshness of agricultural products through the time-controlled venting of the storage container according to the present invention can maintain the freshness of agricultural products and prolong the shelf life of agricultural products in an environmentally friendly and economical way in circulation and storage of agricultural products There is an effect.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of an agricultural freshness keeping apparatus according to the present invention;
2 is a diagram showing a configuration of an agricultural product freshness maintaining apparatus according to the present invention.
3 is a graph showing changes in the gas composition in the vessel for 10 days in Example 1. Fig.
4 is a graph showing changes in the gas composition in the vessel for 14 days in Example 2. Fig.
FIG. 5 is a graph showing the change in the gas composition in the vessel for 10 days in Example 3. FIG.
6 is a graph showing changes in the gas composition in the vessel for 8.5 days in Example 4. Fig.
7 is a graph showing changes in the gas composition in the vessel for 9 days in Example 5. Fig.

According to the present invention,

An input unit for inputting the type of agricultural product and transmitting the kind of the agricultural product to the control unit;

A storage unit for storing a gas partial pressure value corresponding to the type of agricultural product and transmitting the gas partial pressure value to the control unit;

A control unit for controlling the opening and closing of the opening / closing unit by calculating an appropriate gas partial pressure value corresponding to the type of agricultural product transferred from the input unit, from the gas partial pressure value transferred from the storage unit, and calculating an opening / closing time for maintaining the gas partial pressure value;

A ventilation part serving as an air movement passage inside and outside the container for storing agricultural products; And

An opening / closing part having an opening / closing valve for opening / closing the ventilation part;

And a freshness maintaining device for the fresh produce.

The freshness maintaining apparatus for agricultural products according to the present invention

In one embodiment, the gas is oxygen, and the opening / closing time is calculated by the following equations (1) and (3), and the opening / closing valve opens the vent hole during the opening time, And the control unit controls the opening / closing unit during the closing time so that the opening / closing valve closes the vent hole.

[Equation 1]

&Quot; (3) "

In the equation (1) and 3, _r is O opening time ratio, W is weight (kg), R _O2 breathing rate of the oxygen gas consumed ^{(mol kg -1 h -1),} L e of agricultural products: the effective length of the vent a vent port vents to the length obtained by adding the 1.1-fold value of the diameter value (m), D _O2 is the diffusion of oxygen gas is also (m ² / h), R is the gas constant ^{(8.314 JK -1 mol -1),} T is the absolute temperature (K), a is the cross-sectional area of the communication hole _{^{(m 2), p O2,}} t is an oxygen gas titration partial pressure (atm), t _open the opening time (h), t _close the closing time (h), and t _tot is a switching cycle (H) and is an integer from 1 to 48.

In another embodiment, the gas is carbon dioxide, and the opening / closing time is calculated by the following equations (2) and (3), and the opening / closing valve opens the vents And the control unit controls the opening / closing unit by closing the vent hole during the closing time.

&Quot; (2) "

&Quot; (3) "

In Equation 2, and 3, _r is O opening time ratio, W is weight (kg), R is _CO2 respiration rate of the carbon dioxide gas is generated ^{(mol kg -1 h -1),} L e of agricultural products: the effective length of the vent a vent port vents to the length obtained by adding the 1.1-fold value of the diameter value (m), D is the diffusion of carbon dioxide _CO2 gas also (m ² / h), R is the gas constant ^{(8.314 JK -1 mol -1),} T is the absolute temperature (K), a is the cross-sectional area of the communication hole _{^{(m 2), p CO2,}} t is carbon dioxide gas titration partial pressure (atm), t _open the opening time (h), t _close the closing time (h), and t _tot is a switching cycle (H) and is an integer from 1 to 48.

Also, the weight of the agricultural product, the oxygen consumption or the respiration rate of carbon dioxide generation, the effective length of the ventilation hole, the value obtained by adding 1.1 times the diameter of the ventilation hole to the ventilation hole length, the diffusion degree of the oxygen gas, the diffusion degree of the carbon dioxide gas, The partial pressure of oxygen gas, or the partial pressure of carbon dioxide gas may be a value input by the input unit or a value previously stored in the storage unit.

In addition,

1) a control unit receives a type of agricultural product from an input unit;

2) receiving a gas partial pressure value corresponding to the type of agricultural product from the storage unit; And

3) The control unit finds the gas titration partial pressure value corresponding to the type of the agricultural product transferred from the input unit in the step 1) at the gas titration partial pressure value transferred from the storage unit of the 2) Controlling opening and closing of the opening and closing part by an opening and closing valve provided in the opening and closing part;

And a method for maintaining freshness of agricultural products.

The method for maintaining the freshness of agricultural products according to the present invention

In one embodiment, the gas is oxygen, and the opening / closing time is made up of an opening time and a closing time, and is calculated by Equations (1) and (3)

In the step (3), the opening / closing valve opens the vent for the opening time, and the opening / closing valve closes the vent for the closing time so that the control part controls the opening / closing part.

In another embodiment, the gas is carbon dioxide, and the opening and closing time is made up of an opening time and a closing time, and is calculated by Equations 2 and 3

The step 3) is characterized in that the opening / closing valve opens the vent for the opening time, and the opening / closing valve closes the vent for the closing time so that the control part controls the opening / closing part.

The gas partial pressure values for the specific agricultural products are shown in Table 2 below, but are not limited thereto. The gas partial pressure value (atm) represents a value obtained by dividing the following% concentration value by 100.

subject Oxygen (%) carbon dioxide (%) feeling 3 to 5 5 to 8 carrot 5 3 to 4 Strawberry 4 to 10 15 to 20 banana 2 to 5 2 to 5 mushroom 1 to 3 10 to 15 peach 1 to 2 3 to 5 ship 2 to 3 0 to 1 broccoli 1 to 2 5 to 10 Blueberries 5 to 10 15 to 20 Apple 1 to 3 1 to 3 spinach 7 to 10 5 to 10 Fresh vegetables / fruits 3 to 10 3 to 10 cabbage 3 to 5 3 to 6 Orange 5 to 10 0 to 5 Cherry 3 to 10 10 to 15 grape 2 to 5 1 to 3 Green pepper 3 to 5 2 to 8

A computer program composed of differential equations of the following equations (4) and (5) has been developed and used in the construction process of the present invention. These differential equations express the relationship of mass balance in a container for oxygen and carbon dioxide, and confirmed its effectiveness in the following examples.

&Quot; (4) "

&Quot; (5) "

In the above equations (4) and (5), p is the partial pressure of the gas (atm), t is the time (h), V is the vessel volume (m ³ ), N is the number of vents D is the diffusivity of the gas (m ² / h), L _e is the effective length of the ventilation opening and is usually equal to the length of the ventilation hole plus 1.1 times the diameter of the ventilation hole value (m), B is the thickness (mm), a is the cross-sectional area of the communication hole of the container wall surface (m ^2), S is the surface area of the container (m ^2), P is the gas permeability of the vessel wall (mm mol m ^-2 h ^{- 1} atm ^-1), W has produce weight (kg), R is the gas constant ^{(8.314 JK -1 mol -1),} R O2 is respiration rate (mol kg ^-1 h ^-1 in oxygen consumption), R is carbon dioxide _CO2 The respiration rate of the generation (mol kg ^-1 h ^-1 ) and T is the absolute temperature (K), and the subscripts for D, p, and P indicate O 2 and CO 2 respectively.

The control cycle time is determined to be 1 to 48 hours in consideration of the storage period of the whole agricultural product, while maintaining the frequency of the opening and closing of the vent in the control system low, while obtaining a relatively stable gas concentration. This can be determined by the ventilation rate of the item and the size of the vent. The determination of the closure time ratio can be done in a simple manner depending on the target oxygen and carbon dioxide concentrations. In general, assuming that the gas concentration is equilibrated under the condition that the required gas composition is obtained by repeatedly opening and closing the vent, dp _O2 / dt and dp _CO2 / dt at the left side of equations (4) and (5) It can be understood that N, which is an index of the vent opening, is in an average value between 0 and 1. Gas permeation through walls of plastic or metal containers is negligible, assuming that it is very small compared to gas diffusion through the vent. Therefore, in this condition, the open time ratios O _{r at} which the oxygen partial pressure (p _{O2, t} ) and the carbon dioxide gas partial pressure (p _{CO2, t} ) can be obtained from the equations (4) and Can be obtained.

[Equation 1]

&Quot; (2) "

The open time of the open / close valve can be obtained by multiplying the open time ratio O _r represented by Equations (1) and (2) by the total cycle time, and the closure time can be obtained by multiplying (1-O _r ) by the total cycle time. This can be expressed by the following equation (3).

&Quot; (3) "

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the accompanying drawings.

All concentrations used herein refer to% concentrations.

2, the agricultural product freshness maintenance apparatus 100 includes an input unit 110, a storage unit 120, a control unit 130, a ventilation unit 140, and an opening / closing unit 150. Also, the agricultural product freshness maintenance apparatus 100 may include a container.

The container has a function of storing agricultural products and is preferably a reusable plastic tray or box. In some cases, the container may be made of metal, glass, ceramics or a composite material having no gas permeability. When the lid is closed, air is shut off from the outside of the container unless the vent opening is opened by an opening / closing valve provided in the opening / closing part 150. The container may be a primary packaging for direct contact with agricultural produce, or a secondary packaging or storage container containing several small primary packaging. Whatever form and size, the key is to maintain adequate gas composition around the produce in the overall distribution channel. The container is usually made of plastic or metal material with a capacity of 0.5 to 50 L and has a vent which can be opened and closed. The container should contain fruit, vegetables, and other agricultural products, and should be constructed so that it can be closed while maintaining airtightness with a lid. Normally, a flexible material having elasticity is inserted into the closed structure of the container body and the lid, and the airtightness is maintained by being in close contact with each other by the closing pressure.

The input unit 110 receives the type of agricultural product by the user, transmits data on the type of the agricultural product to the controller 130, and may have a form in which a plurality of keypads describing the name of the agricultural product are listed.

The storage unit 120 stores an optimal oxygen partial pressure value and a carbon dioxide gas partial pressure value for maintaining the freshness according to the type of agricultural product.

The control unit 130 requests data from the storage unit 120 based on the data on the type of the agricultural product transferred from the input unit 110 and stores the appropriate partial pressure value of oxygen and / or carbon dioxide corresponding to the type of the agricultural product From the storage unit 120, and performs a comparison operation. The comparison operation is performed by two methods, which will be described below.

1. Method of control by oxygen partial pressure value

Wherein the opening / closing valve opens the ventilation hole during the opening time, and during the closing time, the opening / closing valve closes the ventilation hole The control section controls the opening and closing section to maintain the oxygen gas concentration value in the apparatus within the appropriate partial pressure value range, thereby maintaining the freshness of agricultural products.

2. Control by the value of the partial pressure of carbon dioxide gas

And the calculated CO2 gas partial pressure value for the target agricultural product is calculated by the above Equations 2 and 3. During the opening time, the opening / closing valve opens the ventilation hole, and during the closing time, the opening / closing valve closes the ventilation hole The control section controls the opening and closing section to maintain the carbon dioxide gas concentration value in the apparatus within the appropriate partial pressure value range, thereby maintaining the freshness of the agricultural product.

The weight of the agricultural product may be from 0.02 to 40 kg depending on the size of the container and the agricultural commodity, the absolute temperature may be 272 to 303 K, and the effective length of the ventilation hole, the value of 1.1 times the diameter of the ventilation hole, To 0.17 m, and the cross-sectional area of the ventilation holes may be 7.8 x 10 ^-4 to 1.6 x 10 ^-2 m ^2. The respiration rate of oxygen consumption and the respiration rate of carbon dioxide generation vary depending on temperature and kinds of agricultural products, The degree of diffusion of the gas and the degree of diffusion of the carbon dioxide gas are determined by the temperature. The factors may be input by the input unit, or may be values pre-stored in the storage unit.

The ventilation part 140 connects the inside and the outside of the container of the freshness keeping device 100, and the gas moves through the ventilation part 140. The vent portion is typically mounted to the container side wall, but may be located at the top end of the container, if desired. The opening and closing of the ventilation part is performed by a valve or a capping device controlled by the control part. The size of the vents can vary depending on the size of the container and the breathing characteristics of the agricultural products, but is generally 0.1 to 15.0 cm in length and 0.1 to 2.0 cm in diameter. The shorter the length of the vent and the larger the diameter, the higher the oxygen concentration in the vessel, the lower the carbon dioxide concentration, and a narrower range of ventilation conditions may be established from the correlation analysis of specific items and container conditions. The inlet or the end of the vent is fitted with a valve or capping device that can be sealed and opened. The valve and closure device for opening and closing may be the same diameter as the vent or slightly smaller diameter for ease of attachment. A solenoid valve, a ball valve, a simple piston stopper, etc. can be used for automatic control of the opening and closing of the ventilation by the timer, and a power supply is required for this purpose, which is a battery or a direct AC power source. However, in the agricultural product container system, which is stored for a short period of time, it is also possible to control the temporal opening and closing of the vent hole by the energy stored in spring or spring without power supply.

The opening and closing part 150 opens and closes the ventilation part 140 according to signal transmission from the controller 130. If the opening and closing part is closed, the ventilation part 140 can be completely closed, but there may be some clearance within a range that does not hinder the freshness of the agricultural product. Further, when the opening / closing part is opened, the ventilation part 140 is completely opened.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the examples.

In order to verify the effect of the present invention, experiments were conducted using a large mushroom ( Pleurotus eryngii (De Candolle ex Fries) Quel) and spinach ( Spinacia oleracea ).

Example 1.

To verify the conceptual validity of the present invention, 1.5 kg of mushroom was placed in a 29 × 21 × 21 cm polypropylene (3 mm thick) box and the gas composition inside the container was measured while storing at 5 ° C. The side of the container was pierced to make a 0.5 cm diameter vent (the vent length was 3 mm, same as the wall thickness) and closed for 14 hours with a rubber stopper and stored for 10 days in a 10 hour open cycle. That is, the ventilation open / close ratio was closed at 58% and opened at 42% in the whole cycle 24 hours. The measurement results of the gas composition inside the vessel for 10 days are shown in Fig.

As shown in Fig. 3, oxygen concentration and carbon dioxide concentration oscillated within a stable range after 3 days of storage, though there was some amplitude. That is, when the vents were opened, the oxygen concentration was increased and the carbon dioxide concentration was decreased by a certain amount. The oxygen concentration was increased or decreased between 2% and 9% of oxygen and between 11% and 15% of carbon dioxide. The results of Example 1 confirm that the composition of the gas in the vessel can be maintained in an appropriate range by appropriately adjusting the opening and closing conditions as well as the physical structure of the vent. In the case of mushrooms, it is generally known that freshness is maintained well in the range of oxygen concentration of 2 to 5% and carbon dioxide concentration of 10 to 15%. Example 1 shows that the time-controlled vent opening / closing control of the container having the vent hole controls the internal gas environment It can be an effective means of doing so.

Example 2.

600 g of mushroom was stored in a stainless steel vessel of size 32 × 24 × 17 cm and stored at 5 ° C. The lid portion of the container was made of polypropylene having a thickness of 2 mm. The stainless steel vessel was provided with a ventilation hole having a diameter of 1 cm and a length of 11 cm on the side wall and controlled by a valve system composed of a solenoid valve. As a control, 300 g of mushroom was placed in a 0.03 mm thick breathable polypropylene film bag (28 pores with a size of 5 mm) and stored at the same temperature. The total control cycle was 12.9 hours, and the cycle was closed for 7 hours and 24 minutes at 57% of the opening and closing rate of the ventilation opening, and for 5 hours and 30 minutes at the remaining 43%. The results are shown in Fig.

As shown in FIG. 4, during the storage period of about 14 days, the oxygen concentration gradually decreased to about 4%, and the carbon dioxide concentration increased to about 15%. After 10 days of storage, the oxygen concentration was in the range of 4 to 6% and the carbon dioxide concentration was in the range of 13 to 15%. This gas composition was close to the oxygen concentration of 2 to 5% and the carbon dioxide concentration of 10 to 15%, which are suitable for maintaining freshness of mushrooms. Although it did not reach equilibrium with a stable gas composition, it maintained the gas composition of reduced oxygen and increased carbon dioxide for 14 days. The results of the texture and aerobic total number of bacteria observed after 14 days of storage are shown in Table 3 below.

Quality measurement item Control Example 2 Texture (Cutting strength when cutting a mushroom slice of 1.5 x 1.5 cm in thickness with a 0.26 mm thick blade, N) 21.5 ± 7.0 18.0 ± 3.5 Total number of aerobic bacteria (log (CFU / g) 8.11 ± 0.09 7.00 + 0.02

The breaking strength at the initial stage of storage was 13.1 ± 2.0 N and the aerobic count was 4.07 ± 0.20 log CFU / g.

As shown in Table 3, the agricultural products using the freshness retention method according to the present invention exhibited a smooth texture and low microbial growth as compared with the control group in which the atmospheric gas composition was maintained, thus showing excellent quality preservation. There was no difference between the control and the control.

Example 3.

The body portion was made of stainless steel and the lid portion was stored at 5 ° C in a 27.5 × 20 × 16 cm container made of a polypropylene sheet having a thickness of 2 mm and 450 g of mushroom. A 1.5 mm diameter, 6 cm long steel vent was installed on the side wall and the vent opening was closed for 19 hours (79%) and 5 hours (21%) for the entire 24 hour cycle And stored for 10 days. A ball-type automatic valve was used to automatically control the opening and closing of the vent. As a control, 450 g of mushroom was packed in a bag of breathable polypropylene film (0.03 mm thick) with 28 vents with a diameter of 5 mm. The gas composition measurement results are shown in Fig.

As shown in Fig. 5, oxygen was maintained in the range of 10 to 11% and carbon dioxide 8 to 9% in the container after 5 days of storage. This shows a slightly higher oxygen concentration and a slightly lower carbon dioxide concentration than in Example 2.

In addition, the mushroom quality measured after 10 days of storage is shown in Table 4 below in comparison with the control at which the atmospheric composition was maintained, the small inner surface color change, the soft texture (low cutting strength) and the low microbial contamination degree (aerobic total bacteria number).

Quality measurement item Control Example 2 The inner surface color difference (distance from the initial sample in the Hunter color space (L, a, b) 1.95 + 1.04 0.87 + 0.33 Texture (Cutting strength when cutting a mushroom slice of 1.5 x 1.5 cm in thickness with a 0.26 mm thick blade, N) 19.8 ± 7.07 12.3 ± 3.9 Total number of aerobic bacteria (log (CFU / g) 8.99 ± 0.76 6.61 + - 0.23

At the initial stage of storage, the breaking strength was 9.3 ± 1.9 N, and the aerobic count was 5.73 ± 0.68 log CFU / g.

As shown in Table 4, it was confirmed that the freshness of the agricultural products was well preserved when the inner surface color difference was smaller, the cutting strength was lower, and the microbial contamination degree was lower than that of the control.

Example 4.

The body part was a 27.5 × 20 × 16 cm stainless steel box and the lid part was constructed by mounting a 0.4 cm diameter and 0.06 cm long ventilation port on a wall of a 2 mm thick polypropylene. The container was filled with 400 g of spinach and stored at 10 ° C. Experiments were carried out under the condition that the ventilation hole was closed for 8 hours (33%) and opened for 16 hours (67%) while storing the stainless steel box containing the sample at 10 ° C. That is, the gas composition in the vessel was measured with a gas chromatograph while controlling the opening and closing of the vents under the condition that the total cycle time was 24 hours and the open time ratio was 67% and the closing time ratio was 33%, and compared with the predicted values obtained by equations Respectively. The results are shown in Fig.

As shown in FIG. 6, the oxygen concentration and the carbon dioxide concentration predicted by equations (4) and (5) are comparatively well in agreement with the measured experimental values. By predicting the gas composition that can be obtained by this mathematical model, It was confirmed that designing storage and packaging containers was effective.

Example 5.

A stainless steel box having a body portion of 27.5 × 20 × 16 cm was attached to a vent hole having a diameter of 1.5 cm and a length of 6.0 cm and the vent was closed for 16 hours (67%) and opened for 8 hours (33% 400 g of spinach was stored. The oxygen and carbon dioxide concentrations measured during storage for 9 days at 10 < 0 > C were measured with a gas chromatograph and compared with the predicted values obtained by equations (4) and (5). The results are shown in Fig.

As shown in FIG. 7, the oxygen concentration and the carbon dioxide concentration predicted by equations (4) and (5) are comparatively well matched with the measured experimental values. By predicting the gas composition which can be obtained by the mathematical model, It was confirmed that designing storage and packaging containers was effective.

The results of the comparison of the quality of the spinach stored for 9 days under the conditions of Example 5 with the control package are shown in Table 5 below.

Quality measurement item Control Example 5 Weight loss (%) 19.2 ± 3.3 4.5 ± 0.4 Chlorophyll content (mg / 100 g) 37.9 ± 0.8 44.7 ± 0.5 Vitamin C content (mg / 100 g) 5.1 ± 1.6 5.7 ± 0.5 Sensory preference (7 point scale) 1.3 ± 0.5 4.6 ± 0.6

The initial chlorophyll content was 43.8 ± 3.0 mg / 100 g and the vitamin C content was 14.0 ± 3.5 mg / 100 g.

As shown in Table 5, it was confirmed that the modified gas container packaging was effective in preserving the quality. For the control package, the same weight of spinach was used in a breathable wrapping in a polypropylene film (0.03 mm thick) with 4 pores with a diameter of 5 mm. Sixteen evaluators participated in the sensory preference scale using the preference score scale ranging from 1 point to 7 points (1 point: worst, 7 points: freshest). Example 5 was able to preserve high chlorophyll content while maintaining good sensory freshness with significantly lower weight loss than the control.

Also, the validity of equations (1) and (2) that can determine the open time ratio can be confirmed as follows. As an example shown in FIG. 7, when the ratio of the open time for maintaining the oxygen concentration of about 11% maintained at the equilibrium condition after 7 days of storage was calculated by Equation 1, a value of 0.69 was obtained. That is, assuming that the oxygen partial pressure value (p _{O2, t} ) is 0.11, the values of the gas constant (R) 8.314 JK ^-1 mol ^-1 , the absolute temperature 283 K, (A) 1.768 × 10 ^-4 m ² , spinach weight 0.4 kg, ventilation effective length (L _e ) 0.06 + 1.1 × 0.015 = 0.0675 m, diffusion coefficient of oxygen in the air 0.065 m ² h ^-1 , If the respiration rate of oxygen consumption is 1.11 x 10 ^-3 mol h ^-1 kg ^-1 , the open time ratio O _r is obtained as 0.69. This is very close to the open time ratio 0.67 used in the fifth embodiment, so that the validity of the open time ratio determination according to Equation 1 is shown.

That is, O _r = 0.4 × 1.11 × 10 ^-3 × 0.0675 × 8.314 × 283 / {0.065 × 1.768 × 10 ^-4 × (0.21-0.11) × 101325} = 0.69. Similarly, even at the carbon dioxide concentration, 9 %, The CO2 partial pressure value (p _{CO2, t} ) is 0.09, the diffusion coefficient of carbon dioxide is 0.052 m ² h ^-1 , the respiration rate of carbon dioxide generation is 7.88 × 10 ^-4 mol h ^-1 kg ^-1 Is substituted into Equation 2, the open time ratio 0.69 can be similarly obtained.

That is, O _r = 0.4 x 7.88 x x 10 ^-4 x 0.0675 x 8.314 x 283 / {0.052 x 1.768 x 10 ^-4 x 0.09 x 101325} = 0.69.

These two calculation examples show that the open time ratio can be appropriately set by the present invention when the oxygen partial pressure value of the gas or the partial pressure value of the carbon dioxide gas is set.

However, in a situation where the storage period is short in a realistic agricultural product container package and the expected period of time is not expected to reach equilibrium (for example, in the case of Example 5, the shelf life is about 5 days), the oxygen partial pressure value is slightly lower Or by adjusting the carbon dioxide gas titration value to a high value, the opening time ratio can be reduced. In this case, the modification value of the present invention can be reduced to 0.49 by subtracting 0.2 from the original value of 0.69.

Claims (8)

An input unit for inputting the type of agricultural product and transmitting the kind of the agricultural product to the control unit;
A storage unit for storing a gas partial pressure value corresponding to the type of agricultural product and transmitting the gas partial pressure value to the control unit;
A control unit for controlling the opening and closing of the opening / closing unit by calculating an appropriate gas partial pressure value corresponding to the type of agricultural product transferred from the input unit, from the gas partial pressure value transferred from the storage unit, and calculating an opening / closing time for maintaining the gas partial pressure value;
A ventilation part serving as an air movement passage inside and outside the container for storing agricultural products; And
An opening / closing part having an opening / closing valve for opening / closing the ventilation part;
Wherein the freshness maintaining device comprises: The apparatus according to claim 1, wherein the gas is oxygen, and the opening / closing time comprises an opening time and a closing time, and is calculated by the following equations (1) and (3) Wherein the opening / closing valve closes the vent hole and the control unit controls the opening / closing unit during the closing time.
[Equation 1]

&Quot; (3) "

In the equation (1) and 3, _r is O opening time ratio, W is weight (kg), R _O2 breathing rate of the oxygen gas consumed ^{(mol kg -1 h -1),} L e of agricultural products: the effective length of the vent a vent port vents to the length obtained by adding the 1.1-fold value of the diameter value (m), D _O2 is the diffusion of oxygen gas is also (m ² / h), R is the gas constant ^{(8.314 JK -1 mol -1),} T is the absolute temperature (K), a is the cross-sectional area of the communication hole _{^{(m 2), p O2,}} t is an oxygen gas titration partial pressure (atm), t _open the opening time (h), t _close the closing time (h), and t _tot is a switching cycle (H) and is an integer from 1 to 48. 3. The method according to claim 2, wherein the weight of the agricultural product, the respiration rate of the oxygen gas consumption, the effective length of the ventilation hole plus the value of 1.1 times the ventilation hole diameter, the diffusion degree of the oxygen gas, the absolute temperature, Wherein the gas partial pressure is a value input by the input unit or a value previously stored in the storage unit. 2. The apparatus according to claim 1, wherein the gas is carbon dioxide, and the opening and closing time comprises an opening time and a closing time, and is calculated by the following equations (2) and (3) Wherein the opening / closing valve closes the vent hole and the control unit controls the opening / closing unit during the closing time.
&Quot; (2) "

&Quot; (3) "

In Equation 2, and 3, _r is O opening time ratio, W is weight (kg), R is _CO2 respiration rate of the carbon dioxide gas is generated ^{(mol kg -1 h -1),} L e of agricultural products: the effective length of the vent a vent port vents to the length obtained by adding the 1.1-fold value of the diameter value (m), D is the diffusion of carbon dioxide _CO2 gas also (m ² / h), R is the gas constant ^{(8.314 JK -1 mol -1),} T is the absolute temperature (K), a is the cross-sectional area of the communication hole _{^{(m 2), p CO2,}} t is carbon dioxide gas titration partial pressure (atm), t _open the opening time (h), t _close the closing time (h), and t _tot is a switching cycle (H) and is an integer from 1 to 48. 5. The method of claim 4, wherein the weight of the agricultural product, the respiration rate of the carbon dioxide gas generation, the effective length of the ventilation hole, the value of the ventilation hole length plus 1.1 times the diameter of the ventilation hole, the diffusion degree of the carbon dioxide gas, Wherein the gas partial pressure is a value input by the input unit or a value previously stored in the storage unit. 1) a control unit receives a type of agricultural product from an input unit;
2) receiving a gas partial pressure value corresponding to the type of agricultural product from the storage unit; And
3) The control unit finds the gas titration partial pressure value corresponding to the type of the agricultural product transferred from the input unit in the step 1) at the gas titration partial pressure value transferred from the storage unit of the 2) Controlling opening and closing of the opening and closing part by an opening and closing valve provided in the opening and closing part;
Wherein the freshness of the fresh produce is maintained. The method according to claim 6, wherein the gas is oxygen, and the opening and closing time comprises an opening time and a closing time, and is calculated by the following equations (1) and (3)
Wherein the step 3) is a step in which the opening and closing valve opens the ventilation hole during the opening time and the opening and closing valve closes the ventilation hole for the closing time so that the control part controls the opening and closing part.
[Equation 1]

&Quot; (3) "

In the above equations (1) and (3), O _r is the ratio of the open time, W is the weight of the agricultural product in kg, R _O2 is the respiration rate of oxygen consumption (mol kg ^-1 h ^-1 ), L _e is the effective length of the vent value vent vent to the length obtained by adding a 1.1 times the diameter (m), D _O2 is the diffusion of oxygen gas is also (m ² / h), R is the gas constant ^{(8.314 JK -1 mol -1),} T is absolute temperature ( K), a is the cross-sectional area of the communication hole _{^{(m 2), p O2,}} t is an oxygen gas titration partial pressure (atm), t _open the opening time (h), t _close the closing time (h), and t _tot is the opening and closing cycle Time (h), which is an integer from 1 to 48. The method according to claim 6, wherein the gas is carbon dioxide, and the opening / closing time comprises an opening time and a closing time, and is calculated by the following equations (2) and (3)
Wherein the step 3) is a step in which the opening / closing valve opens the ventilation hole during the opening time and the opening / closing valve closes the ventilation hole during the closing time so that the control part controls the opening and closing part.
&Quot; (2) "

&Quot; (3) "

In Equation 2, and 3, _r is O opening time ratio, W is weight (kg), R is _CO2 respiration rate (mol kg ^-1 h ^-1) of carbon dioxide, L _e of agricultural products: as the effective length of the vent value vent vent to the length obtained by adding a 1.1 times the diameter (m), D is the diffusion of carbon dioxide _CO2 gas also (m ² / h), R is the gas constant ^{(8.314 JK -1 mol -1),} T is absolute temperature ( K), a is the cross-sectional area of the communication hole _{^{(m 2), p CO2,}} t is carbon dioxide gas titration partial pressure (atm), t _open the opening time (h), t _close the closing time (h), and t _tot is the opening and closing cycle Time (h), which is an integer from 1 to 48.

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