JPH0252040A - Ethylene adsorbent and method for keeping freshness of plant - Google Patents

Abstract

PURPOSE:To keep the freshness of a plant by preparing a cuprous salt supported ethylene adsorbent by immersing a porous carrier in a solution of a cupric salt and a reducing agent and using the same to remove ethylene generated from a plant. CONSTITUTION:A water-soluble cupric salt and a reducing agent are dissolved in water and a porous carrier is quickly immersed in the prepared solution before the reducing reaction of copper is advanced or the solution is sprayed to the porous carrier and, thereafter, the impregnated carrier is dried in an inert gaseous atmosphere to prepare a cuprous salt supported ethylene adsorbent. The amount of the copper salt fixed to the carrier is about 1-35wt.%. For example, after activated carbon or activated alumina is immersed in a 6% aqueous copper sulfate solution as a carrier, a 10% aqueous ferrous sulfate solution is added thereto to precipitate a ferrous salt to support the same by the carrier. The adsorbent thus obtained shows high ethylene removing capacity and can be used repeatedly.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a technology for preserving the freshness of plants such as fruits and vegetables and flower petals, and more specifically, a method for removing ethylene generated from plants such as fruits and vegetables or flower petals during storage. This invention relates to an adsorbent suitable for the purpose of keeping plants fresh, and a method of keeping plants fresh using the adsorbent.

[Conventional techniques and their problems] Low temperature storage, C
A storage (Controlled Atmosphere)
Storage) or sealed packaging using polyethylene bags, etc., are generally adopted.

Fruits, vegetables and flower petals take in oxygen even after they are harvested.

Life continues to be maintained using organic matter (starch, sugars, proteins, amino acids, etc.) stored in the body as an energy source, and it releases back acid gas, water, ethylene, etc. as metabolites. Of these, ethylene is a plant hormone that promotes the overripeness and aging of fruits and vegetables, as well as the flowering and growth of flower petals. Therefore, in order to maintain the freshness of fruits, vegetables, and petals after harvesting during storage and distribution, it is desirable to remove the ethylene generated from them.

As methods for preserving the freshness of fruits, vegetables, and petals during storage or distribution, there are two known methods: one in which the ethylene generated from these is removed using an adsorbent, and the other method in which the ethylene is removed using an oxidizing agent. In this case, the adsorbent is a porous adsorbent such as activated carbon or zeolite, and the oxidizing agent is a porous adsorbent such as activated carbon or zeolite.

Those in which potassium permanganate or chlorine dioxide is impregnated or adsorbed on zeolite or the like, and those in which a bromine compound is supported on activated carbon are used.

However, the atmosphere in which fruits, vegetables, or flowers are stored or packaged for transportation generally has high humidity and a high carbon dioxide concentration.

For this reason, the method using an adsorbent has the disadvantage that the adsorbent cannot have a high ethylene adsorption capacity due to the influence of coexisting moisture and carbon dioxide gas, and there is also a risk that the adsorbed ethylene may be desorbed.

This method cannot be expected to have a sufficient ethylene removal effect.On the other hand, regarding the method using a 5-oxidizing agent, potassium permanganate has excellent ethylene removal performance, but since it is a poisonous substance, it depends on how it is handled. becomes a source of environmental pollution, and there are problems in its disposal. Furthermore, methods using chlorine dioxide are not recommended because the chlorine gas comes into direct contact with fruits and vegetables. Furthermore, methods using bromine compounds such as bromates also have problems in terms of treatment of generated hydrogen bromide.

[Means for Solving the Problems] The present invention uses a cuprous salt-supported ethylene adsorbent prepared from a cupric salt, a reducing agent, and a porous carrier to remove ethylene generated from plants such as fruits and vegetables and flower petals. use.

The ethylene removing agent of the present invention comprises a water-soluble cupric salt (for example, a halide salt such as a sulfate, a nitrate, a chloride, an organic acid salt, an ammine complex salt), a reducing agent (for example, a ferrous salt, Ascobic acid, hydrochloric acid and droxyamine, hydrazine sulfate, oxalic acid, stannous chloride, metal steel, sulfite, sulfurous acid, thiosulfate, phosphite, etc.) are dissolved in water or other suitable solvent to remove copper. It can be prepared by quickly immersing the porous carrier in this solution before the reduction reaction progresses, or by spraying the solution onto the porous carrier and then drying it in an inert gas atmosphere. Alternatively, a water-soluble cupric salt may be first supported on a porous carrier by an impregnation method or a spraying method, and then the carrier may be removed by filtration or the like and dried, or the above-mentioned method may be directly carried out without taking it out. It is also possible to adopt a method in which the cupric salt is reduced to the cuprous salt by immersion in or spraying the reducing agent solution, and then dried in an inert gas atmosphere. Alternatively, after pre-soaking the porous support in an aqueous solution of cupric salt.

There is no problem in adopting a method of adding a reducing agent to reduce to cuprous salt.

Generally, cuprous salts are insoluble in water or other solvents, so it is difficult to support them on a porous carrier by impregnation or the like. Incidentally, cuprous chloride is soluble in high yield hydrochloric acid or ammonia solutions, but when these solutions are used to support cuprous salts on porous carriers, there are problems with corrosion and handling.

In contrast, the adsorbent of the present invention uses a water-soluble cupric salt and converts it into a cuprous salt using a reducing agent, so it can be supported on a porous carrier in a uniformly dispersed state. It has great features that make it possible.

Porous carriers used in the present invention include carbonaceous porous materials such as activated carbon, activated alumina, alumina-based carriers such as alumina sol, titanium oxide, zeolite 5 clay (acid clay, activated clay), bentonite, and various other natural products. Minerals (aluminosilicate, etc.) can be used, and the shape is powder-like or fibrous.

A honeycomb shape or the like can be arbitrarily selected.

The carrier is preferably porous and has a large specific surface area, but is not particularly limited, and in practice it is suitable to select one that is non-toxic, inexpensive, and easy to handle. The amount of copper salt immobilized on the carrier is 0.1 to 50% by weight, preferably 1 to 35% by weight. If the amount is too small, a sufficient effect will not be obtained, and if the amount is too large, the ethylene removal effect will not be improved accordingly.

The adsorbent of the present invention may carry a water repellent, an antioxidant, etc. for the purpose of further improving water resistance and oxidation resistance.

Furthermore, although it is preferable to use the ethylene adsorbent of the present invention at a low temperature, it exhibits sufficient effects even at room temperature.

The ethylene adsorbent of the present invention is filled into a suitable container made of, for example, a bag made of breathable non-woven fabric, paper, cloth, polyethylene, or wire mesh, etc., and the container is placed in a packaging box or packaging for vegetables, fruits, or flowers. By storing them, the freshness of fruits, vegetables, or flowers can be maintained. Alternatively, one or more scrubbers filled with the ethylene adsorbent of the present invention may be utilized to remove ethylene from the warehouse.

FIG. 1 is a flow diagram of such an embodiment,
Gas in the storage 1 is introduced via a blower 2 into a scrubber 5 filled with a dehumidifying agent (activated alumina, zeolite, silica gel, activated carbon, etc.) 3 and an ethylene removing agent 4 of the present invention to remove ethylene, The gas discharged from the scrubber is humidified by a humidifier 6 and then returned to the storage 1 to prevent ethylene from accumulating in the storage. In this case, the ability of the scrubber to remove ethylene decreases over time due to the passage of internal gas, so if you want to use it again, as shown in Figure 1, you can remove ethylene by passing dry inert gas, etc. Can restore removal ability.

The ethylene adsorbent of the present invention also functions as an effective oxygen scavenger for preserving freshness since it also carries the base agent 'a'. In addition, in some types of CA storage, combustion gas such as LPG is introduced into the storage to lower the oxygen concentration, but in this case carbon monoxide is mixed in.6 However, the adsorbent of the present invention must be used. For example, this harmful C○ can also be adsorbed and removed.

[Function] The ethylene adsorbent of the present invention, which is composed of a cuprous salt, a reducing agent, and a porous carrier, has the ability to remove ethylene that is generated from fruits, vegetables, and flowers, and causes aging of these fruits. significantly superior to. In addition, since this adsorbent utilizes weak complex formation between cuprous salt and ethylene, it can be easily regenerated by exposure to inert gas, so it can be used repeatedly. There is.

Example 1 After immersing activated carbon, activated alumina, titanium Mide, and bentonite as carriers in a 6% copper sulfate aqueous solution,
A 10% ferrous sulfate aqueous solution was added to precipitate and support the cuprous salt on the carrier.

Thereafter, the mixture was filtered and dried at 100° C. under a nitrogen atmosphere to prepare an ethylene adsorbent.

The ethylene adsorbent O, Sg of the present invention thus obtained was
0.00 mol.
Air containing 0 ppm was injected and the mixture was kept at room temperature, and the change in ethylene concentration over time was analyzed using gas chromatography. Table 1 shows the ethylene concentration after 30 minutes when the ethylene concentration was almost stable.

In addition, after the test was completed, the ethylene adsorbent was regenerated by heating to 100°C in a nitrogen atmosphere, and then the test was conducted in the same manner.The results of repeating this process three times are as shown in Table 1. Ta. For comparison, the results in the case of using only the carrier are also shown in Table 1.

Table 1 Example 2 After immersing activated carbon and activated alumina as carriers in a 6% aqueous copper sulfate solution, they were filtered and dried. The obtained activated carbon and activated alumina supporting copper sulfate were immersed in a 10% ferrous sulfate aqueous solution or ascorbic acid aqueous solution to reduce cupric in the carrier to cuprous. Thereafter, the carrier was taken out and dried at 100° C. under a nitrogen atmosphere to prepare an ethylene adsorbent.

The same tests as in Example 1 were conducted on the ethylene adsorbent of the present invention thus obtained. The results are shown in Table 2.

[Effects of the invention] Potassium permanganate-containing ethylene removers conventionally used to preserve the freshness of fruits and vegetables require carriers to carry a large amount of potassium permanganate, which is extremely harmful and difficult to handle. Potassium permanganate is consumed by reaction with ethylene and cannot be reused, but the ethylene adsorbent of the present invention is not consumed by contact with ethylene.

The ethylene removing agent of the present invention gradually loses its ethylene removing ability when it comes into contact with ethylene, but it easily recovers its ethylene removing ability by placing it under a flow of dry inert gas or by slight heating. Therefore, the ethylene removing agent of the present invention can be used repeatedly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for removing ethylene generated in a fruit and vegetable storage using a scrubber filled with the ethylene adsorbent of the present invention. 1...Storage 2...Blower 3...Dehumidifier floor 4
...Ethylene adsorbent bed 5...Scrubber 6...Humidity conditioner

Claims (1)

[Claims] 1. A cuprous salt-supported ethylene adsorbent prepared from a cupric salt, a reducing agent, and a porous carrier. 2. A method for keeping plants fresh, which comprises removing ethylene generated from plants using a cuprous salt-supported ethylene adsorbent prepared from a cupric salt, a reducing agent, and a porous carrier.