JP2890356B2 - How to keep horticultural crops fresh - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for maintaining freshness of horticultural crops, and more particularly, to a method for maintaining freshness of horticultural crops for suppressing ripening, aging and discoloration.

[0002]

2. Description of the Related Art It is known that horticultural crops generate ethylene and acetaldehyde from themselves during storage, and as a result, cause physiological disorders and accelerate their ripening, aging and discoloration. In order to prevent this, there has been proposed a method of removing the above-mentioned various gases generated from horticultural crops. Typical examples thereof include a method of physically adsorbing these gases with activated carbon and a method of oxidative decomposition with potassium permanganate. However,
The former method has a limitation in the removal rate, while the latter method has a disadvantage that the removal rate is slow.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently removing ethylene and acetaldehyde generated from horticultural crops to maintain the freshness of the horticultural crop for a long period of time. The present inventors have conducted intensive studies to achieve this object, and as a result, when irradiating a specific semiconductor with ultraviolet light and bringing it into contact with ethylene and acetaldehyde, these compounds are rapidly and efficiently decomposed. The present inventors have found that the present invention has been completed based on this finding.

[0004]

Thus, according to the present invention, there is provided a method of supplying an atmosphere gas of a horticultural crop with a fan to a semiconductor having a band gap of 0.5 to 5 eV under ultraviolet irradiation. A method for maintaining the freshness of a horticultural crop, and irradiating ultraviolet rays while supplying an atmosphere gas of the horticultural crop to a semiconductor having a bandgap of 0.5 to 5 eV by using a fan. A method for maintaining freshness of a horticultural crop is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION 0.5 used in the present invention
Specific examples of a semiconductor having a band gap of 5 to 5 eV include:
For example, zinc oxide, tungsten trioxide, titanium dioxide,
Metal oxides such as strontium titanate and ferric oxide; metal chalcogenides such as zinc sulfide, cadmium sulfide, lead sulfide, zinc selenide and cadmium selenide; Group IV elements such as silicon and germanium;
For example, gallium-phosphorus, gallium-arsenic, indium-
III-V compounds such as phosphorus; for example, polyacetylene,
Examples include, but are not limited to, organic semiconductors such as polypyrrole, polythiophene, polyaniline, and polyvinylcarbazole. In addition, a semiconductor obtained by doping the semiconductor with impurities such as arsenic, phosphorus, aluminum, boron, sodium, and halogen can also be used in the present invention. Further, by carrying platinum or the like on the surface of the semiconductor, the catalytic effect can be enhanced.
Among these semiconductors, those having a band gap of 2 to 4 eV are preferable from the viewpoint of effect, and metal oxides such as tungsten trioxide, titanium dioxide, zinc oxide and the like are preferable from the viewpoint of toxicity and availability. Mixed crystals are preferred.

In the present invention, one kind of semiconductor may be used alone, but two or more kinds of semiconductors may be used in the form of a mixed crystal or the like. Further, it can be used in combination with an adsorbent such as activated carbon or acid clay. In the present invention, the amount of the semiconductor used is not particularly limited, and is selected in consideration of the type and amount of the target horticultural crop, the type and intensity of the light source, the type of the semiconductor, and the like. In the present invention, the form of use of the semiconductor is not particularly limited, but those in which the semiconductor is supported on a carrier such as a nonwoven fabric, a porous film, activated carbon, zeolite, or diatomaceous earth, the semiconductor particles are fixed and scattered. It is advantageous in that it is not easily used and has good activity because it is easily contacted with the atmospheric gas of horticultural crops, and can be used as it is as a filter. In the present invention, it is preferable that the particle size of the semiconductor is small from the viewpoint of the effect.
A size of up to 1,000 μm is used, but a size larger than this can also be used.

The ultraviolet light used in the present invention has a wavelength of 400 nm or less, preferably from 400 to 200 nm.
nm near-ultraviolet light. These ultraviolet rays can be generated by using an ultra-high-pressure mercury lamp, a xenon lamp, or a low-pressure mercury lamp alone or in combination. A light source modified to have a wavelength distribution characteristic that meets the purpose may be used. Of course, light rays other than ultraviolet rays, for example, visible light rays may be included. In the present invention, as a specific example of a method of irradiating a semiconductor with ultraviolet light, a method of applying a semiconductor to a surface of a light source or a reflector of the light source and irradiating the same, a support impregnated or coated with the semiconductor around the light source. It is possible to show a method of providing the light and irradiating the light.

In the present invention, in order to bring the atmosphere gas of a horticultural crop into contact with the semiconductor, the atmosphere gas of the horticultural crop is placed in an open or closed reactor equipped with an ultraviolet irradiation device.
It is introduced by a fan in a batch or continuous manner. The fan is not particularly limited as long as it allows the atmospheric gas of the horticultural crop to flow so as to come into contact with the semiconductor. According to the method of the present invention, since the decomposition of ethylene and acetaldehyde is performed efficiently, the freshness preserving method of the present invention is limited to only the distribution process of transporting and storing horticultural crops, which are conventional applications. Instead, it can be applied to extending the storage period of horticultural crops in refrigerators at ordinary homes.

[0009]

EXAMPLES The present invention will be described in more detail with reference to Examples and Examples. Parts and% in Reference Examples and Examples are based on weight unless otherwise specified.

REFERENCE EXAMPLE 1, COMPARATIVE REFERENCE EXAMPLE 1 0.4 g of various powdery semiconductors shown in Table 1 were put into separate 80 ml Palex conical Erlenmeyer flasks, and the container contained about 125 ppm ethylene. After purging with air, it was sealed with a silicone rubber stopper. Next, an ultra-high pressure mercury lamp (illuminance: 10 mW / cm ² , main wavelength: 365 nm) placed at a distance of 20 cm from the Erlenmeyer flask was turned on, and the temporal change of the ethylene concentration in the container was tracked by gas chromatography (experiment number). 1, 3, and 4). Also, an aqueous polyvinyl alcohol solution is cast on a glass plate, and when this is turned into a semi-dried film, anatase-type titanium dioxide (particle diameter: 21 mμ) is sprayed and further placed and completely dried to obtain a film. The polyvinyl alcohol film thus obtained was cut to obtain 0.9 g of a sample film containing 0.4 g of a semiconductor, and the same test was performed on this sample (Experiment No. 2). Further, for comparison, a test similar to Experiment No. 1 was performed on a system without using a semiconductor (Experiment No. 5). Table 1 shows the results. Also,
An air introduction tube and a discharge tube are attached to the Erlenmeyer flask charged with the titanium dioxide, and while irradiating the flask with ultraviolet rays, air containing ethylene is circulated through the air introduction tube and the discharge tube to perform a test similar to the above. Similar results were obtained when this was done. From these results, it is understood that ethylene is efficiently removed by the method of the present invention.

[0011]

[Table 1]

Reference Example 2, Comparative Reference Example 2 Titanium dioxide was subjected to the same test as Reference Example 1 or Comparative Reference Example 1 except that acetaldehyde was used instead of ethylene. Table 2 shows the results.

[0013]

[Table 2]

From the results shown in Table 2, it can be seen that acetaldehyde was efficiently removed by the method of the present invention.

EXAMPLE 1 120 loaded with 50 g of anatase type titanium dioxide
g of polyvinyl alcohol film and light red plum 2
0 and a germicidal lamp (illuminance: 3 mW / cm ² , dominant wavelength: 254)
nm) and a closed container (30 cm x 25 cm x 37 cm in internal volume) equipped with a fan for air circulation were placed in a thermostatic chamber. After turning on the germicidal lamp, changes in the appearance of the plum for 10 days were observed. For comparison, the same test was conducted except that a polyvinyl alcohol film supporting anatase-type titanium dioxide was not placed.

When polyvinyl alcohol carrying titanium dioxide was not placed, all of the plums turned brown and 15 of the 20 plums lost their shape. In contrast, when a polyvinyl alcohol film carrying titanium dioxide was placed and the germicidal lamp was turned on, all the plums changed shape except that the light red color of the plum was slightly darker than at the start of the experiment. There was no. From the above results, it can be seen that the freshness of the horticultural crop can be maintained for a long time by the method of the present invention.

[0017]

Thus, according to the present invention, ethylene and acetaldehyde released by horticultural crops can be degraded more efficiently and more sustainedly than in the prior art, and horticultural crops can be stored for a longer period of time. Becomes possible.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-99853 (JP, A) JP-A-55-39257 (JP, A) JP-A-1-252244 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) A23B 7/00

Claims (2)

(57) [Claims] 1. A method for maintaining freshness of a horticultural crop, wherein an atmosphere gas of the horticultural crop is introduced into a semiconductor having a bandgap of 0.5 to 5 eV under irradiation with ultraviolet rays and brought into contact with the semiconductor. 2. A method for maintaining freshness of a horticultural crop, comprising irradiating ultraviolet rays while introducing and contacting an atmosphere gas of the horticultural crop with a fan to a semiconductor having a band gap of 0.5 to 5 eV.