JP3349375B2 - Environmentally controlled storage of fruits and vegetables - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling and storing fruits and vegetables for a long period of time by controlling the atmosphere in a storage.

[0002]

2. Description of the Related Art Storing fruits and vegetables such as tangerines, kabosu, apples and the like for a long period of time is extremely demanded from the viewpoint of avoiding loss due to deterioration of stored products in the distribution process and stable shipping throughout the year. For this reason, various freshness technologies are being studied, but basically the following (1)-
This is achieved by adjusting (5).

[0003] (1) oxygen concentration according to the type of each vegetable, (2)
CO ₂ concentration according to the type of each vegetable, (3) low temperature of 0 to 15 ° C. according to the type of each vegetable, (4) humidity control of about 80% of relative humidity, (5) with maturity of each vegetable Removal of volatile organic substances such as ethylene, aldechet, and terpene, which form and grow and become aging factors. Of these, low-temperature storage is widely used, but for adjusting atmospheric gas, fruits and vegetables are applied with a volatile organic substance decomposer. To this extent, a method of adsorbing and decomposing volatile organic substances generated by wrapping in wrapping paper is used.

[0004]

In order to maintain the freshness of fruits and vegetables during storage, first, oxygen is removed from the storage at the beginning of storage (O ₂ pull-down). Also,
When storage is started, oxygen is consumed by metabolism of fruits and vegetables, and CO ₂ is released. For this reason, it is no longer necessary to remove oxygen. Rather, it is necessary to supply oxygen suitable for metabolism from outside the system, but this can be easily performed because air only needs to be supplied to the storage. At this stage, it is rather important to continuously remove metabolic CO _{2 from} the system. Therefore To the CO ₂ removed by adsorption currently led reservoir gas into the activated carbon adsorption tower, a method of releasing the saturated activated carbon with CO ₂ in air purge regeneration with from outside of the system have been taken. Since the removal of CO _{2 out} of the system is performed almost at the atmospheric pressure, the burden is not so large.

[0005] Activated carbon is a good adsorbent from the viewpoint of avoiding deactivation due to moisture during air regeneration, but the amount of adsorbed CO ₂ is reduced to 1/2 to 1/3 as compared with zeolite. The amount of adsorbent used increases accordingly. In addition, volatile organic substances such as ethylene, acetoaldehyde and terpene, which are generated simultaneously with the generation of CO ₂ , are factors for the growth and aging of fruits and vegetables, and it is necessary to remove these substances. However, the adsorption amount of activated carbon is so large. Absent. Therefore, at present, oxidative decomposition by halogen peroxide supported on activated carbon is often used. In this method, the oxidative decomposition reaction is significantly reduced at a relative humidity of 50% or more.
% Or less of water in the previous stage or 30% of the processing gas.
It is necessary to raise the temperature to at least ° C., and these pretreatments are considerably complicated. Another problem is that halogen oxides are extremely expensive.

[0006] The present invention has been made in view of such circumstances, and 1) the release of CO _{2 to} the outside of the system, and 2) the removal of volatile organic substances, which were conventionally realized by separate apparatuses. Provided is an environmentally controlled storage method for fruits and vegetables that can be realized with a single-stage adsorption tower filled with high silica zeolite and that can reduce equipment costs, reduce power consumption, and simplify operation and maintain ease. The purpose is to:

[0007]

Means for Solving the Problems The first invention of the present application is an environment for fruit and vegetables which keeps the concentration of CO ₂ necessary for maintaining the freshness of crops in storage and removes volatile organic substances such as ethylene, acetaldehyde and terpene. In a controlled storage method, Si
A pentasil zeolite having an O ₂ / Al ₂ O ₃ ratio of 70 or more,
Ultra-stable Y-type zeolite with SiO ₂ / Al ₂ O ₃ ratio of 5 or more
Or a mesoporate with an SiO ₂ / Al ₂ O ₃ ratio of 5 or more
Using an adsorption tower filled with one of the silica zeolites of lath silicate, under the condition that the concentration of the gas in the storage containing the volatile organic substance in the storage is high, the storage in the storage containing the CO ₂ and the volatile organic substance is performed. Gas to the silica zeo
CO 2 and brought into contact with the _light, after performing the adsorption of volatile organic compounds, CO ₂ adsorbed on the silica zeolite,
An environmentally controlled storage method for fruits and vegetables, which comprises releasing volatile organic substances from the system by contacting them with air . Application
Invention 2 discloses the CO ₂ necessary for maintaining the freshness of the crops in the storage.
Concentration retention, ethylene, acetaldehyde, terpene, etc.
Controlled Storage of Fruits and Vegetables to Remove Volatile Organic Substances
Pentagon having an SiO ₂ / Al ₂ O ₃ ratio of 70 or more
Silzeolite, super cheap with SiO ₂ / Al ₂ O ₃ ratio of 5 or more
Constant Y-type zeolite or SiO ₂ / Al ₂ O ₃ ratio 5
Any one of the above mesoporous silicates
Using an adsorption tower filled with zeolite, the volatility of the storage
Under conditions where the concentration of gas in the storage containing organic substances is high
Is the gas in the storage containing CO ₂ and volatile organic substances.
CO ₂ , volatile by contacting with the silica zeolite
After the adsorption of organic substances, the silica zeolite
The CO ₂ and volatile organic substances deposited are guided under reduced pressure
Environmentally controlled storage of fruits and vegetables characterized by their release to the outside
Is the law. The third invention of the present application is a method for preserving the freshness of crops in storage.
The concentration of CO ₂ retention necessary lifting, ethylene, acetaldehyde
Fruits and vegetables that remove volatile organic substances such as hides and terpenes
In the environmentally controlled storage method of the present invention, the SiO ₂ / Al ₂ O ₃ ratio
70 or more pentasil zeolites, SiO ₂ / Al ₂ O
₃ ratio of 5 or more ultrastable Y-type zeolite or SiO ₂
/ _Al 2 Izu _{O 3} ratio of 5 or more mesoporous silicate
Uses an adsorption tower packed with a single silica zeolite
Of the gas in the storage containing volatile organic substances
Contains CO ₂ and volatile organic substances under high concentration conditions
The reservoir in gas which contacted with the silica zeolite
After adsorption of CO ₂ and volatile organic substances by
Reduces CO ₂ and volatile organic substances adsorbed on liquorite
Contact with air from outside the system under pressure conditions to release
Controlled storage method for fruits and vegetables characterized by being released to the environment
It is.

In the present invention, the means for releasing the CO ₂ and volatile organic substances adsorbed on the high silica zeolite to the outside of the system include: 1) bringing the CO ₂ and volatile organic substances adsorbed on the high silica zeolite into contact with air; 2) CO ₂ and volatile organic substances adsorbed on high silica zeolite are released out of the system under reduced pressure conditions. 3) CO ₂ and volatile organic substances adsorbed on high silica zeolite Are brought into contact with air from the outside of the system under reduced pressure conditions to be released and released outside the system.

In the present invention, the high silica zeolite includes a pentasil zeolite having a SiO ₂ / Al ₂ O ₃ ratio of 70 or more, an ultra-stable Y-type zeolite having a SiO ₂ / Al ₂ O ₃ ratio of 5 or more, and SiO ₂ / Al Mesoporous silicate having a ₂ O ₃ ratio of 5 or more can be used.

[Operation] The operation of the present invention is as follows.
When the storage conditions reach a steady state following the release of oxygen from the storage at the start of storage (O ₂ pull-down), the stored fruits and vegetables consume oxygen to release CO ₂ due to the metabolic mechanism,
It also emits volatile organic substances such as ethylene, terpene, and formaldehyde. Here, when the adsorption tower is brought into contact with high silica zeolite, which maintains the ability to adsorb CO ₂ and volatile organic substances even in the presence of moisture, the CO ₂ and volatile organic substances are adsorbed and low concentration CO ₂ , As volatile organics flow from the top of the tower, this gas is returned to the storage and CO ₂ ,
Used to control the increase in the concentration of volatile organic substances.

Then, the adsorbed CO ₂ and volatile organic substances are separated from the adsorbent by bringing the adsorption or the like into contact with air or leading to reduced pressure, or by contact with air under reduced pressure conditions. discharge. By this method, 1) release of CO _{2 to} the outside of the system, 2)
The removal of volatile organic substances can be achieved with a single-stage adsorption tower packed with one type of high silica zeolite, which is achieved by rationalizing environmental control equipment, 1) reduction of equipment, 2) reduction of power consumption, 3) operation, Simplification of maintenance is achieved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an apparatus necessary for realizing the method for controlling and storing fruits and vegetables according to the present invention will be described with reference to FIG. The number 1 in the figure is, for example, about 3 m in volume.
³ storage. The storage 1 stores 1 ton of kabosu as fruits and vegetables. The environmental control conditions for the storage 1 were as follows: temperature 5 ° C., relative humidity 80% (temperature 5 ° C.).
At 80 ° C., the relative humidity is 80%), the composition of the atmosphere gas is oxygen 5 vol%, CO _{2 5} vol%, nitrogen 90 vol%
Need to be kept. A nitrogen production device 3 is connected to the storage 1 via a flow path 2a. Here, as the nitrogen producing apparatus 3, a membrane method, a pressure switching method using an oxygen adsorbent and a nitrogen adsorbent can be considered, but in this embodiment, a nitrogen producing apparatus by a pressure swing method filled with molecular sieve type carbon 3A is used. It was adopted.

Further, an adsorption tower 6 filled with high silica zeolite 5 is connected to the storage 1 via a flow path 2b provided with a valve 4b. Here, as the high silica zeolite, a pentasil zeolite having a SiO ₂ / Al ₂ O ₃ ratio of 20 or more, or a SiO ₂ / Al ₂ O ₃ ratio of 5 or more is used.
Ultra-stable Y-type zeolite (USY) or Si
A mesoporous silicate having an O ₂ / Al ₂ O ₃ ratio of 5 or more is effective. A blower 7 is connected to the storage 1 via a flow path 2c provided with a valve 4c. The adsorption tower 6 is connected to the blower 7 via a flow path 2d provided with a valve 4d.

The flow path 2c between the valve 4c and the blower 7
The flow path 2d between the valve 4d and the adsorption tower 6 is connected by a bypass flow path 2e provided with a valve 4e. A flow path 2d provided with a valve 4f is connected to a flow path 2d between the blower 7 and the valve 4d. The oxygen-containing gas in the storage 1 is discharged out of the system from the flow path 2f. The storage 1 is connected to a bypass flow passage 2g having a valve 4g interposed therebetween, whereby air outside the system is sent into the storage 1. Reference numeral 2h in the figure is a flow path connected to the top of the adsorption tower 6 and provided with a valve 4h.

Next, a description will be given of a method for environmentally controlled storage of fruits and vegetables using the apparatus having such a configuration. i) First, immediately after storing 1 ton of spill in storage 1, the temperature in storage 1 is cooled from room temperature to 5 ° C. using a refrigerator (not shown) or the like, and oxygen is removed from the system ( O ₂ pull-down) is performed. The nitrogen production apparatus, flow path 2
95% by volume or more of nitrogen from a is supplied at a flow rate of 0.5 m ³ N / h, and the oxygen-containing gas in the storage 1 is discharged out of the system from the open valve 4c, the blower 7, the valve 4f, and the flow path 2f. After a 40 hour purge, a nitrogen concentration of 94 vol% was reached.

Ii) After that, oxygen in the storage 1 is consumed by respiratory metabolism under the environment control condition of kabosu, and CO ₂ is released. At the same time, about 1 μg / h of volatile organic substances such as ethylene, acetaldehyde and terpene are released. Their sensitivity as growth and aging factors is 0.1 p
pm, so that 0.1 p
pm or less. The replenishment of the oxygen consumption is not so difficult, since the oxygen concentration in the storage 1 is monitored and the air outside the system is supplied to the storage 1 by opening the valve 4g from the flow path 2g as a shortage. The removal of CO ₂ is required selective separation and removal of CO _2.

Iii) In the present invention, CO ₂ is removed from the system by a single-column type CO ₂ adsorption tower filled with 3 kg of high silica zeolite. When the metabolic mechanism of kabosu becomes a steady state and the CO ₂ in the storage 1 exceeds the set CO ₂ concentration of 5 vol%, the atmospheric gas in the storage 1 is circulated from the open valve 4c, the blower 7 and the valve 4d to adsorb the column. 6, CO ₂ and volatile organic substances such as ethylene, acetaldehyde, and terpene are adsorbed to the high silica zeolite from the front of the adsorption tower 6, and a gas not containing these gases flows from the top of the adsorption tower 6 and the valve 4 b Then, the CO ₂ is returned to the storage 1 to maintain the CO ₂ concentration and remove the volatile organic substances. After this, the operation returns to the step of adsorbing CO ₂ and volatile organic substances again.

FIG. 2 shows an adsorption time of 5 minutes, a regeneration time of 5 minutes, a circulating gas amount of 50 lN / min, and an air purge gas amount of 75 lN / min.
Pentasil zeolite as an adsorbent under the conditions of air purge pressure-atmospheric pressure, water concentration of 0.5 vol% in circulating gas, and SiO ₂ / A of pentasil zeolite.
Removal rate of CO ₂ , ethylene, terpene, and acetaldehyde when the l ₂ O ₃ ratio was changed (each curve (a) ~
(D)).

As the pentasil zeolite, UPO samples having different SiO ₂ / Al ₂ O ₃ ratios were used.
If the SiO ₂ / Al ₂ O ₃ ratio is less than 70, the removal rates of CO ₂ , ethylene, terpene, and acetaldehyde are all significantly reduced, but this is probably due to deactivation caused by co-adsorption of water.

FIG. 3 shows an adsorption time of 5 minutes, a regeneration time of 5 minutes, a circulating gas amount of 50 lN / min, and an air purge gas amount of 75 lN / min.
X, Y-type zeolite containing ultra-stable Y-type zeolite is used as an adsorbent under the conditions of air purge pressure-atmospheric pressure, water concentration of 0.5 vol% in circulating gas,
Removal rate of CO ₂ , ethylene, terpene, and acetaldehyde when the ₂ / Al ₂ O ₃ ratio was changed (each curve (a) to
(D)).

X and Y ultrastable zeolites include UP
Samples of Company O having different SiO ₂ / Al ₂ O ₃ ratios were used. When the SiO ₂ / Al ₂ O ₃ ratio is less than 5, the removal rates of CO ₂ , ethylene, terpene, and acetaldehyde are greatly reduced.
It is considered that hydrophilicity was increased on the O ₂ / Al ₂ O ₃ ratio side, and deactivation was caused by co-adsorption of water.

FIG. 4 shows an adsorption time of 5 minutes, a regeneration time of 5 minutes, a circulating gas amount of 50 lN / min, and an air purge gas amount of 75 lN / min.
Min, air purge pressure-atmospheric pressure, water concentration in circulating gas 0.5 vol%, mesoporous silicate as adsorbent, CO ₂ and ethylene when SiO ₂ / Al ₂ O ₃ ratio was changed. , Terpene, and acetaldehyde removal rates (curves (a) to (d), respectively).

The mesoporous silicate is prepared by adding sodium silicate and aluminum nitrate to a predetermined SiO ₂ / Al ₂ O ₃
A solution (this is referred to as solution A) obtained by mixing so as to obtain a template / (Si solution) was prepared by dissolving dodecyltrimethylammonium chloride in hydrochloric acid (referred to as solution B).
+ Al) The precipitate obtained by adding the mixture to have a ratio of 0.12 was aged for 3 hours, dried, calcined (removing the template), and pelletized (1.6 mmφ) SiO ₂ / A.
Samples with different l ₂ O ₃ ratios were used. SiO ₂ / Al
_{When the 2} O ₃ ratio is less than 5, the removal rates of CO ₂ , ethylene, terpene, and acetaldehyde are greatly reduced. However, as with other zeolites, hydrophilicity is low on the low SiO ₂ / Al ₂ O ₃ ratio side. This is probably because the water content increased and deactivation occurred due to co-adsorption of water.

Although it is known that these high silica zeolites exhibit hydrophobicity, in this experiment, they stably adsorb CO ₂ even in the presence of water, and together with the adsorption of CO ₂ , ethylene, terpene, acetaldehyde, etc. It was confirmed that organic matter was adsorbed. Before the organic matter exits from the rear of the tower, the valves 4b, 4c, 4d are closed and the valves 4e, 4f, 4
h, the air outside the system is introduced from the flow path 2h to the adsorption tower 6, and CO ₂ adsorbed by the countercurrent contact between the air and the adsorbent,
Ethylene, terpene, acetaldehyde and the like are released and released out of the system from the flow path 2f, and the regeneration is completed.

In order to remove adsorbed CO ₂ and volatile organic substances, 1) countercurrent purging with air at atmospheric pressure and 2) countercurrent purging with air under reduced pressure were attempted. It has been confirmed that removal can be achieved by using at least 1.2 times the method of calculating the amount of purge gas proposed by Skullstrom from the adsorbent. In this embodiment, Pa
= Pd = 1 and K = 1.5. The following equation (1)
The equation for calculating the purge gas amount according to the Skullstrom rule is shown in FIG.

Gp = K * G0 * Pd / Pa (1) In the equation (1), Pa is an adsorption pressure, Pd is a regeneration pressure, Gp is a countercurrent purge gas amount, and G0 is an inlet gas amount in the adsorption step. is there. K is an experimental constant, and 1.2 or more is recommended. If it is 1 or less, regeneration is not established.

As described above, in the method of the present invention, the adsorption tower 6 filled with high silica zeolite 1) removes CO ₂ necessary for environmental control, and 2) removes volatile organic substances such as ethylene, terpene and acetaldehyde. Will be implemented. In the nitrogen production in the above embodiment, the power consumption for producing 1 m ³ N of nitrogen is 0.2 to 0.8 KwH. Further, the power consumption required for removing volatile organic substances such as CO ₂ and ethylene is about 0.01 to 0.05 Kwh, and the emission of CO ₂ and volatile organic substances to the outside of the system is extremely small. It can be seen that is implemented.

[0028]

As described above in detail, according to the present invention, 1) release of CO _{2 to} the outside of the system, which has conventionally been realized by separate devices,
2) The removal of volatile organic substances can be realized with a single-stage adsorption tower filled with one kind of high silica zeolite, and the reduction of equipment cost, power consumption, and simplification of operation and ease of maintenance are ensured. It is possible to provide a method for environmentally controlled storage of possible fruits and vegetables.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for environmentally controlled storage of fruits and vegetables according to one embodiment of the present invention.

FIG. 2: SiO ₂ / Al ₂ O _{3 of} pentasil zeolite
FIG. 4 is a characteristic diagram showing a relationship between a ratio and a removal rate of CO ₂ , ethylene, terpene, and acetaldehyde.

FIG. 3 SiO ₂ / Al ₂ O _{3 of} ultra-stable Y-type zeolite
FIG. 4 is a characteristic diagram showing a relationship between a ratio and a removal rate of CO ₂ , ethylene, terpene, and acetaldehyde.

FIG. 4 SiO ₂ / Al ₂ O of mesoporous silicate
FIG. 3 is a characteristic diagram showing a relationship between the ₃ ratio and the removal rates of CO ₂ , ethylene, terpene, and acetaldehyde.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Storage, 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h ... Flow path, 3 ... Nitrogen production apparatus, 4b, 4c, 4d, 4e, 4f, 4g, 4f ... Valve, 6 ... Adsorption tower, 7 ... High silica zeolite.

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takuya Kitada 1 Nagoya Laboratory, Iwazuka-cho, Nakamura-ku, Nagoya City, Aichi Prefecture Inside Nagoya Research Laboratory, Mitsubishi Heavy Industries, Ltd. 3-1-1, Asahicho, Mitsubishi Heavy Industries, Ltd. Air Conditioning Works (72) Inventor Mitsutoshi Sudo 3-1-1, Asahimachi, Nishi-Biwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Air Conditioning Works (56) References JP JP-A-7-241134 (JP, A) JP-A-64-43148 (JP, A) JP-A-63-229118 (JP, A) JP-A-63-317039 (JP, A) JP-A-1-148341 (JP) , A) JP-A-63-317040 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A23B 7/148 B01J 20/18

Claims (3)

(57) [Claims] 1. CO required for maintaining freshness of agricultural products in a storage
_2. An environmentally controlled storage method for fruits and vegetables which maintains the concentration of ₂ and removes volatile organic substances such as ethylene, acetaldehyde, terpene, etc., comprising a pentasil zeolite having a SiO ₂ / Al ₂ O ₃ ratio of 70 or more.
G, ultra-stable Y-type Zeola having a SiO ₂ / Al ₂ O ₃ ratio of 5 or more
Or a mesopo with SiO ₂ / Al ₂ O ₃ ratio of 5 or more
Using an adsorption tower filled with any one of silica zeolites of silica silicate and a high concentration of gas in the storage containing volatile organic substances in the storage, CO ₂ ,
Wherein the reservoir interior gas containing volatile organic substances Shirikaze
After adsorbing CO ₂ and volatile organic substances by contact with olilite , C adsorbed on the silica zeolite
An environmentally controlled storage method for fruits and vegetables, wherein O ₂ and volatile organic substances are brought into contact with air and released outside the system. 2. CO required for maintaining freshness of agricultural products in a storage.
Concentration maintenance of ₂ , ethylene, acetaldehyde, terpene
Controlled storage of fruits and vegetables to remove volatile organic substances such as
Pentasilzeolia having a SiO ₂ / Al ₂ O ₃ ratio of 70 or more.
G, ultra-stable Y-type Zeola having a SiO ₂ / Al ₂ O ₃ ratio of 5 or more
Or a mesopo with SiO ₂ / Al ₂ O ₃ ratio of 5 or more
One of the silica silicates
Using packed adsorption towers, containing volatile organic substances in storage
Under the condition where the concentration of the gas in the storage tank is high, CO ₂ ,
The gas in the storage containing volatile organic substances is
Adsorption of CO ₂ and volatile organic substances by contact with olilite
After performing the above, C adsorbed on the silica zeolite
Guides O ₂ and volatile organic substances under reduced pressure and releases them out of the system
An environmentally controlled storage method for fruits and vegetables. 3. CO required for maintaining freshness of agricultural products in storage.
Concentration maintenance of ₂ , ethylene, acetaldehyde, terpene
Controlled storage of fruits and vegetables to remove volatile organic substances such as
Pentasilzeolia having a SiO ₂ / Al ₂ O ₃ ratio of 70 or more.
G, ultra-stable Y-type Zeola having a SiO ₂ / Al ₂ O ₃ ratio of 5 or more
Or a mesopo with SiO ₂ / Al ₂ O ₃ ratio of 5 or more
One of the silica silicates
Using packed adsorption towers , containing volatile organic substances in storage
Under the condition where the concentration of the gas in the storage tank is high, CO ₂ ,
The gas in the storage containing volatile organic substances is
Adsorption of CO ₂ and volatile organic substances by contact with olilite
After performing the above, C adsorbed on the silica zeolite
O _2, contact the volatile organic substances and air from the outside under reduced pressure system
An environmentally controlled storage method for fruits and vegetables, characterized in that the fruits and vegetables are released by being touched and released .