CA2026215A1

CA2026215A1 - Storage vessel for fruits, vegetables and flowering plants and storage method for the same

Info

Publication number: CA2026215A1
Application number: CA 2026215
Authority: CA
Inventors: Takeyoshi Yamada; Kazumi Iwata
Original assignee: Individual
Current assignee: Teijin Ltd
Priority date: 1989-01-27
Filing date: 1990-01-26
Publication date: 1990-07-28
Also published as: WO1990008474A1

Abstract

ABSTRACT
A storage vessel and a storage method in which a permselective film which is permselective to carbonic acid gas and to oxygen gas occupies a part of a vessel section.
This construction enables control of concentrations of carbonic acid gas and of oxygen gas contained in a storage atmosphere gas composition in the vessel so as to be suitable for fruits, vegetables or flowering plants to be stored.

Description

2 i~ 2 ~ 3 DESCRIPTION
STORAGE VESSEL FOR FRUITS, VEGETABLES AND
FLOWERING PLANTS AND STORAGE METHOD FOR STORING
THE SAME
TECHNICAL FIELD
The present invention relates to a storage vessel for fruits, vegetables or flowering plants, and to a storage method for storing them. More particularly, the present invention relates to a storage vessel and a stor-age method in which the vessel includes a vessel section apart of which is occupied by a film having a permselec-tivity to carbonic acid gas and oxygen gas so that con-centrations of carbonic acid gas and of oxygen gas in the storage atmosphere gas composition in the vessel can be controlled so as to be suitable for storing fruits, vege-tables or flowring plants.
BACKGROUND ART
Vegetables, fruits and flowering plants (here-after, sometimes referred to also as "green goods and fruitsn) which are indispensable for our daily life must be fresh. Because it takes some time before the green goods and fruits come to hands of consumers after they have been harvested by producers, they lose freshness rapidly and their quality decreases. Thus, development of a preservation method for the green goods and fruits is desired which method ensures that they do not lose fresh-ness after harvest nor their quality decreases. In addi-tion, because yields of the green goods and fruits are largely dependent on season and weather, their supply tends to be insufficient for meeting consumers' needs, resulting in that their prices rise suddenly while when the crop is abundant, amount of supply is excessive so that their prices fall suddenly, which sometimes compels producers to abandon the green goods and fruits. Hence, development of a preservation method which can maintain freshness of green goods and fruits has been desired in 2 i .~

order to ensure their constant supply. Among the flower-ing plants, blooms or flowers for appreciation have short lives and tend to undergo deterioration and discoloring or in worst cases tend to suffer their falling while they are being transferred from producers to consumers. If flowers can be preserved in a state of buds just before efflo-rescence or in an initial stage of efflorescence, there can be obtained very great advantages. Green goods and fruits continue to respire even while they are being preserved. Hence, in order to stop the ripening of the green goods and fruits to deter their deterioration, it is important to inhibit their respiration.
Therefore, various preservation methods have been practiced which include, for example, a method which uses a low preservation temperature, a method which re-moves ethylene, a ripening hormone, and a method which uses oxygen and carbonic acid gas in the storage atmos-phere in concentrations suitable for preservation. The method which uses a low preservation temperature has been used generally because it is simple but has a limitation that its preservation period is relatively short and is insufficient for most of the green goods and fruits. A
method has been proposed in which ethylene, a ripening hormone for green goods and fruits, is removed by de-composing it with potassium permanganate, and the methodhas been put in practical use limitedly. However, because of toxicity of potassium permanganate, the use of the method has caused a great problem.
It has already been known that in order to store green goods and fruits, it is possible to preserve the green goods and fruits for a considerably long period by retaining the atmosphere gas composition, particularly carbonic acid gas and oxygen gas, in optimal concentration ranges. The preservation method in which the storage atmosphere gas composition is kept constant is called CA
storage (Controlled Atmosphere Storage), and has been put h.~ ^j in practice for long term preservation of apples and the like. However, in the CA storage, there is required not only an installation for the production of nitrogen gas or carbonic acid gas which is to be supplied as a substitute 5 gas to a storehouse just after collection and introduction of green goods and fruits in the storehouse in order to make the atmosphere gas composition suitable for the storage but also there is required an apparatus for remov-ing or varying the concentration of carbonic acid gas in 10 the atmosphere in order to make the atmosphere gas com-position constant because oxygen is consumed and carbonic acid gas is generated during storage. Accordingly, a large scale installation is required to store them and it is applied to only very limited green goods and fruits.
15 Development of a preservation method has thus been desired which uses no large scale installation and can be used easily by producers, distributors, retailers or producers.
As for the method for making a storage atmosphere gas composition easily without using a large scale instal-20 lation for the production of a storage atmosphere gas,various methods have heretofore been proposed which uti-lize respiration of green goods and fruits itself and use films or porous membranes for retaining appropriate bal-ance in concentrations between carbonic acid gas produced 25 and oxygen gas consumed as a result of the respiration.
French Patent No. 1,567,996 discloses a preser-vation bag for green goods and fruits which has a specific surface area of from 0.1 to 0.25 m2 per unit volume in m3 and which is composed of a silicone elastomer film having 30 a thickness of from 50 to 100,~ m over a surface area cor-responding to from 25 to 50 % of total surface area.
Transactions of the ASAE, 1982, p. 433-436, reports results of storing carrots, celeries, turnips and cabbages using a silicone membrane having a thickness of 35 100 m and discloses that the silicone membrane is ef-fective for establishing an atmosphere composed of a high concentration CO2 and a low concentration ethylene, and that carrots were stored for 52 weeks, and celeries, turnips and cabbages were stored for 16 weeks.
Int. J. Refrig, 1989, vol 9, July, p. 234-239, reports storage experiments conducted using a Tergal R net provided with a continuous coating layer of silicone rubber having a thickness of about 90~m and varying its area to be used to thereby making atmospheres having a carbonic acid gas level of 1.5 %, 3.5 % and 5.5 %, res-pectively, and preserving celeries in the atmospheres.
Japanese Patent Publication ~Kokoku) No. Sho59-48610 describes an invention which uses a housing room made of a silicone membrane having a thickness of 50~4m, but this has to employ complicated means such as maintain-ing the pressure therein at an absolute pressure of from 1to 10 mmHg just after introducing agricultural products, decreasing the temperature therein to from 0 to 15C by evaporation of water and introducing nitrogen, air or the like gas from outside (cf. from the lower left column to upper right column on page 1).
Acta Horticultarae, 38, 1974, p. 33-46, dis-closes that when artichokes, asparaguses, carrots and turnips were stored in a polyethylene bag provided with a window made of dimethylpolysiloxane, storage period were prolonged drastically as compared with the case when they were preserved in air.
Japanese Patent Publication (Rokai) No. Sho 62-235088 discloses the transportation of vegetables, fruits or flowers for appreciation after putting them in a vessel which has an opening of a predetermined area in a part of the bulk thereof and a gas permselective film provided at the opening, cooling them under vacuum and filling carbonic acid gas and nitrogen gas so as to reach atmospheric pressure. The publication discloses as such permselective membrane a Puman membrane (silicone mem-brane) having respective gas permeabilities (ml/m2, 24 hr, atm) of 2.5 x 105 for oxygen, 1.3 x 106 for carbon dioxide, and about 107 for ethylene.
Japanese Patent Publication (Kokai) No. Sho 63-152638 and corresponding EP-A-0270764 disclose a vessel made of a substantially gas impermeable material and provided with a gas permeable panel made of microporous plastic membrane which vessel can give presumed oxygen flux for the green goods and fruits, and flowers for appreciation put therein. The gas permeable panel has a carbonic acid gas/oxygen gas permeance ratio of 1/1 so that sum of carbonic gas and oxygen gas in a housing room of the vessel is always 21 %.
The publications above describe also in addition to such panel having a carbonic acid gas/oxygen permeance ratio of 1/1, a panel having a carbonic acid gas/oxygen permeance ratio of, for example, 4 : 1 or 8 : 1 can be attached as a permeance adjustment membrane (cf. upper left column).
However, there is no disclosure on specific examples of such permeance adjustment membrane. The vessel disclosed in the above Publications is characteris-tic in that it always uses a microporous membrane as a necessary requirement. Because the pores of the micro-porous membrane have sizes as large as allowing permeation of oxygen gas, transpiration of aqueous vapor occurs inevitably. In addition, the vessel described in the above-described publications have a limitation that it is substantially impossible to apply it to preservation of green goods, fruits and flowers for appreciation for which oxygen gas and carbonic acid gas concentrations suitable for storage are in a range of no higher than 5 96, respect-ively, because atmosphere gas composition suitable for the preservation of freshness varies depending on the kind of the green goods or flowers for appreciation.
U.S. Patent No. 3,507,667 describes a bag in-tended to achieve similar object by using a silicone r~ r~

elastomer membrane having a thickness of from 50 to 150~ m. Such a thick membrane as above is practically undesirable because area required to obtain a suf-ficiently high permeation rate of a gas becomes extremely large. If the membrane has a large thickness the membrane is disadvantageous as a wrapping material.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a storage vessel for fruits, vegetables or flowering plants.
Another object of the present invention is to provide a storage vessel which can adjust gas composition of storage atmosphere so as to be suitable for a specific fruit, vegetable or flowering plant as an object to be stored.
Still another object of the present invention is to provide a storage vessel of which a part of a vessel section is occupied by a permselective film having perm-selectivity for carbonic acid gas and oxygen gas in order to achieve the above-described object of the present invention.
Yet another object of the present invention is to provide a storage vessel which uses a permselective film having a very small thickness and thus enables ef-ficient control of the gas composition of storage atmos-phere with a reduced area of permselective film used.
Further object of the present invention is to provide a storage vessel of which the area of a perm-selective film to be used is designed accordingly by setting up a ratio of the amount of carbonic acid gas generated to the amount of oxygen consumed during storage of vegetables, fruits or flowering plants as an objective for preservation to be from 0.3 to 0.8.
Still further object of the present invention is to provide a storage method for vegetables, fruits or flowering plants which forms an atmosphere comprising ~ ~ ~ ii 2 ~ ~

carbonic acid gas and oxygen gas having a composition suitable for storing the objective to be stored by means of a permselective film.
Other objects and advantages of the present invention will be apparent from the following description.
The above-described object5 and advantages of the present invention is achieved primarily by a storage vessel for fruits, vegetables or flowing plants comprising a vessel section and a permselective film constituting a part of the vessel section which is permselective to carbonic acid gas and oxygen gas, wherein the perm-selective film has a thickness of no higher than 30~m.
BRIEF DESCRIPTION DRAWINGS
Fig. 1 illustrates a bag having a window made of a permselective film according to the present invention;
Fig. 2 illustrates a box having a window made of a permselective film ac¢ording to the present invention;
Fig. 3 illustrates a bag made of a permselective film according to the present invention as contained in a corrugated box;
Fig. 4 illustrates other type of a preservation box having a window made of a permselective film according to the present invention;
Fig. 5 is a graph representing changes in con-centrations of gases in the storage atmosphere dependingon storage period according to Examples 1 and 2 and Com-parative Examples 1 and 2 relative to storage of kabosu.
(Citrus sphaerocarpa hort. ex Tanaka);
Fig. 6 illustrates other type of box having a window made of a permselective film according to the present invention, in Fig. 6, 1 designates a gas perm-selective film;
Fig. 7 is a graph representing changes in con-centrations of gases in the storage atmosphere depending on storage period according to Examples 3 and 4 and Com-parative Examples 4 and 5 relative to storage of kabosu.

- 8 - ~ v7 (Citrus sphaerocarpa hort. ex Tanaka);
Fig. 8 is a gra~h representing changes in con-centrations of gases in the storage atmosphere depending on storage period according to Example 6 relative to storage of pears;
Fig. 9 is a graph representing changes in con-centrations of gases in the storage atmosphere depending on storage period according to Comparative Example 7 relative to storage of pears;
Fig. 10 is a graph representing changes in concentrations of gases in the storage atmosphere depend-ing on storage period according to Example 7 relative to storage of apples; and Fig. 11 is a graph representing changes in concentrations of gases in the storage atmosphere depend-ing on storage period according to Comparative Example 8 relative to storage of apples.
BEST MODE FOR CARRYING OUT THE INVENTION
The storage vessel of the present invention has a form which prevents green goods and fruits from contact-ing atmosphere outside the vessel directly while green goods and fruits are being housed and stored therein and may be of any size and shape. The storage vessel of the present invention may be, for example, a box or a bag.
Alternatively, it may be a larger ones such as a con-tainer.
The storage vessel of the present invention has a thin film which is permselective to carbonic acid gas and oxygen gas and has a thickness of no greater than 30~m as a part of its vessel section. In other words, the storage vessel could be said to have a window made of the permselective film as a part of its vessel section.
The permselective film must have a permselec-tivity to both carbonic acid gas and oxygen gas. The permselective film has a ratio of the permeation rate of carbonic acid gas to the permeation rate of oxygen gas of, ~ s~ 3 _ g _ for example, from 2 to 10. The ratio of permeation rates is preferably from 2 to 7. If the ratio of permeation rates is smaller than 2, the concentration of carbonic acid gas in the storage atmosphere tends to increase to a level higher than is desirable for the preservation of green goods and fruits (for example, from 1.5 to 7 %). On the other hand, if the ratio of permeation rates is larger than 10, the concentration of carbonic acid gas in the storage atmosphere tends to be lower than is desirable for the preservation of the green goods and fruits.
The permselective film generally has respective permeation rates for other gases, for example, nitrogen gas, aqueous vapor, ethylene gas or the like. The perm-selective membrane preferably has a ratio of the permea-tion rate of aqueous vapor to the permeation rate of oxygen gas of from 10 to 500. Because of having a perm-selectivity in that range, it can prevent green goods and fruits during storage from wilting or drying up, or in-versely putrefaction due to a large amount of moisture.
As for materials for the permselective film, there can be cited, for example, polysiloxanes; hydro-carbon polymers such as polyolefins, polydienes and poly-acetylenes; poly~alkyl phenyl ethers); polyphosphazenes;
and the like. As for the polysiloxanes, there can be cited, for example, polydimethylsiloxane/polycarbonate copolymers, polysiloxane-containing polyureas, and polysiloxane-containing polyamides. Examples of the hydrocarbon polymers include polymethylpentenes and co-polymers thereof; polymethylhexenes; polybutenes; poly-butadienes; poly~alkyl-substituted acetylenes); and alkyl-silyl group-containing polymers such as polytrimethyl-vinylsilanes, polytrimethylallylsilanes and polytrimethyl-silylacetylenes. As for the poly(alkyl phenyl ethers), there can be cited, for example, poly~2,6-dimethylphenyl ether), and poly(2,6-diethyl-phenyl ether). As for the polyphosphazenes, there can be cited, for example, poly-h ~ 2 ~.j diethoxyphosphazene, poly[di(p-methylphenoxy)phosphazene], and poly(N-propyl-N'-diethylphosphazene).
Of these, particularly permselective films made of polydimethylsiloxane/polycarbonate copolymers, poly~4-methylpentene-l and poly(2,6-dimethylphenyl ether), res-pectively, as a material are preferred.
Because the thinner the permselective film, the higher is the permselectivity thereof, only a small area of the membrane is required in order to obtain an objec-tive value of the gas composition in the housing. In thepresent invention, the permselective film has a thickness of no greater than 30~ m. Of course, the film is composed of a uniform membraneous layer having no defects such as pinholes on the surface or inside thereof. If the film thickness is greater than 30~m, its permeabilities to gases are low and most part of the surface of the vessel has to be occupied by the membrane in order to establish the objective atmosphere gas composition, resulting in that the feature of simplicity is lost. In addition, if the film thickness is no smaller than 30~m, permeation rate of aqueous vapor is low, and as a result moisture condensation phenomenon tends to occur on the surfaces of green goods and fruits, which causes putrefaction.
The thickness of the permselective film is in a range of preferably from 0.05 to lO~m.
In the present invention, the permselective film is thin as described above, and therefore used as sup-ported on a support. As for the support, a porous support is used advantageously which is substantially impermeable to carbonic acid gas and oxygen gas. As for the support, there can be cited, there can be cited, for example, microporous membranes or unwoven fabrics made of poly-ethylene or polypropylene. The microporous membrane of polypropylene is available, for example, as CELGUARD
produced by Celanese Chemical Co. The support is to support the permselective film but gives no substantial 2 ~ 2 iJ 2 ..i, influence to the permselectivity of the permselective film.
Furthermore, it is preferred that the perm-selective film used in the present invention be protected with a breathing protective material having a low air permeation resistance in order to protect the film regard-less of whether a support is present or not. As the breathing protective material, there can be used advan-tageously one which has an air permeation resistance by lower than 1/20 time, preferably lower than 1/40 as high as that of the permselective film.
As for the protective material, there can be cited, for example, porous plastics films, plastics nets, plastics unwoven fabrics, and fiber fabrics. As for the method for protecting the permselective film with the protective material, there can be cited, for example, a method in which the film is sandwiched between the pro-tective materials, a process in which the protective material is used as a substrate on a surface of which is formed a permselective film by direct coating or casting the material of the permselective film, or a method in which the film is bonded to the protective material with an adhesive.
In the storage vessel of the present invention, the effective membrane area of the permselective film varies more or less depending on the conditions such as kind and amount of green goods and fruits to be stored, and atmosphere gas composition suitable for storage but occupies, for example, from 0.005 to 10 %, and preferably from 0.02 to 10 %, of total surface forming a vessel section.
A part of the vessel section constituted by the permselective film, i.e., a window made of the perm-selective film may be provided in the vessel singly or in a plural number no less than 2. It is desirable that the number of such window is made larger at will for an in-2 i~ ~ a,3 ~

creased volume of the storage vessel and for an increased amount of the objective to be stored so that the distri-bution of the atmosphere gas composition in the vessel decreases. Practically, the area of a single window is preferably from 0.5 to 5 cm2, and therefore, from this point of view, it is advantageous that the number of the window is 2 or more when the total surface of the storage vessel exceeds 30 cm . The shape of the window may be, for example, a circle, an ellipse, a square or a rectan-gle. Particularly, the circle and ellipse are preferred.
In the vessel of the present invention, forforming a window by attaching a permselective film to a part of the vessel section, there can be used, for example, a method in which a part of the vessel section is cut off so as to have a desired area and a permselective film is extended and bonded to that part with an adhesive or the like; a method in which a vessel section is produced using a thermoplastic material, a part of it is cut off, and all margins of circumferential portion and a film are fixed to each other by heat fusion (in this case, instead of heat fusion of the membrane itself, heat fusion of the support of the membrane or of the protective material may be carried out); and the like. Particularly, the latter heat fusion fixing method is preferred.
As the material for forming the vessel section, any material can be used that has an almost negligible permeability to air and mositure. In the case where the vessel is a bag, there can be used, for example, poly-olefin films such as a polyethylene film and a polypro-pylene film; polyester films; polystyrene films, polyvinyl alcohol films; polyvinyl chloride films; cellophane;
polyurethane films; or composite films composed of these films or paper and an aluminum foil or a plastics foil laminated or coated thereon. In the case where the vessel is a box, there can be used, for example, polyolefin resin plates such as a polyethylene plate or a polypropylene ~2 2~

plate; polyester sheets; polystyrene sheets; polyvinyl alcohol sheets; polyvinyl chloride sheets; cellophane;
polyurethane sheets; composite sheets composed of these sheets or corrugated paper and aluminum or plastics laminated or coated thereon; or sheets made of aluminum, galvanized iron, white iron, stainless steel, glass, wood or the like.
Using the storage vessel of the present inven-tion, fruits such as peaches, pears, apples, persimons, grapes, kabosu, sudachi (Citrus sudachi hort. ex Shirai), oranges, and green plums; vegetables such as asparaguses, tomatoes, broccolis, spinaches, lettuces, and rape blos-soms; flowring plants such as chrysanthemums, carnations, roses, sweet peas, lilies, gentians, freesias, gladio-luses, irises, tulips, and daffodils can be stored ad-vantageously to retain sreshness of these green goods and fruits.
Table 1 below shows an example of storage gas composition suitable for some of the above-described green goods and fruits extracted from a literature: Shokuhin Ryutsu Gijutsu (Rinji Zokango), Vol. 16, No. 14, p.45 (1987) [translation: Food Distribution Technology (an extra number), Vol. 16, No. 14, p.45 (1987)]. Using the storage vessel of the present invention, the storage atmosphere gas compositions suitable for the green goods and fruits exemplified in Table 1 can be established easily. This will be elucidated specifically by the fol-lowing examples.

~12'',21 Table 1 Suitable Co~sition ~%) Green Goods Temperature Storage ~ r~ts (C) _ _ ~ ~i~

Fuyugaki O 8 26 months (persimon) pear 0 4 59-12 months Tomato 6-8 5-9 3-105 weeks Peach 0-2 7-9 3-54 weeks Green plum 0 3-5 2-3 Lettuce 102-3 nths Fig. 1 to 4 illustrate specific examples of the storage vessel of the present invention. The construction of the vessel illustrated in Fig. 1 comprises a main body 1 of a bag, a cut-off portion (window) 2 formed on a side surface of the bag, a permselective film 3 heat-fused on margins around the cut-off portion, a fruit 4 to be stored, and a seal 5 for keeping the inside of the bag air-tight from the open air. Fig. 2 illustrates a box which comprises a box 6 provided on a surface thereof with a sheet of a thermoplastic film 1' having a cut-off por-tïon 2 to which a permselective film 3 is heat-fused.
Fig. 3 illustrates an example in which the preservation bag illustrated in Fig. 1 is housed in a corrugated box 6 provided with air holes 7, and Fig. 4 illustrates an example in which a corrugated box having a gas-impermeable film or foil 8 laminated on inner surfaces thereof is used and its lid is sealed air-tight.
Fig. 6 illustrates an example in which a plural-ity of windows made of a permselective film are provided on a surface of a box made of a plastics material which is substantially impermeable to gases.
Investigations by the present inventors revealed that upon storage experiments carried out on green goods and fruits using the above-described storage vessel of the present invention, assumption made in conventional storage of green goods and fruits that the amount of oxygen gas which the green goods and fruits as an objective to be stored is equal to the amount of carbonic acid gas gener-ated by the green goods and fruits differs drastically from fact, resulting in that the assumption gives an unnegligible remarkable influences on results of storage.
Therefore, according to the present invention, based on the results of investigation demonstrated for the first time by the present inventors, there is also provid-ed a method for storing fruits, vegetables or flowering plants in a storage vessel a part of a vessel section of which is occupied by a permselective film permselective to carbonic acid gas and oxygen gas, wherein concentra-tions of carbonic acid gas and of oxygen gas in a storage atmosphere gas composition in the vessel is determined by setting up a ratio of the amount of carbonic acid gas generated to the amount of oxygen consumed by the fruits, vegetables or flowering plants to be stored to a value in a range of from 0.3 to 0.8 and determining area of the permselective film to be used and the amount of the fEuits, vegetables or flowering plants to be stored.
More specifically, upon storing a specific item of green goods and fruits, the area of the permselective film used (A) and the amount of the item of the green goods and fruits to be stored (B) are determined by deter-mining the concentration of carbonic acid gas (WCO ) and the concentration of oxygen gas ~WO ) in the storage atmosphere gas composition in the vessel by a relationship represented by the following formula:

2 ~ 3 2 L

W0 = Yo2 Ko x ~A/B) , wco2 ~ x W02 + ( O~, X Yo2 + YC2 ) wherein C: unit conversion coefficient = 3.655 x 10 6, G: the amount of oxygen consumed by the fruit, vegetable or flowing plant, A: the area of the permselective film (cm2), B: the amount of the fruit, vegetable or flower-ing plant to be packed (kg) Ko : the oxygen permeation rate of the perm-selective film (cc~cm /sec/cmHg) ~: the gas selectivity of the permselective film (= carbonic acid gas permeability/oxygen permeability) ,~: the amount of carbonic acid gas generated by the fruit, vegetable or flowering plant/amount of oxygen consumed by the fruit, vegetable or flowering plant (= 0.3 to 0.8), Y0 : the concentration of oxygen in the air, YC0 : the concentration of carbonic acid gas in the air WO : the concentration of oxygen gas in the atmosphere gas composition WcO : the concentration of carbonic acid gas in 2 the atmosphere gas composition It could be said that in the conventional method for storing green goods and fruits, the amount of the permselective film and that of the green goods and fruits to be stored have been determined assuming that the value of ~ in the above-described formula is 1, and in the long run it does not mean that the green goods and fruits have been stored in an atmosphere having a desired gas composi-tion.

232~2~5 According to the present invention, while the value of ~ varies depending on green goods and fruits to be stored, it is possible to store them in a desired gas atmosphere by setting up the value of ~ in a range of from 0.3 to 0.8 based on facts contrary to the conventional method, and therefore it is possible to prolong the storage period for storing, for example, green goods and fruits.
Also, according to the present invention, there is provided a vessel described below which is designed so that the amount of green goods and fruits to be stored is from 10 to 50 % of the store space therein.
More specifically, according to the present invention, there is further provided a storage vessel for storing a specific fruit, vegetable or flowering plant a part of a vessel section of which is occupied by a perm-selective film permselective to carbonic acid gas and oxygen gas, wherein the permselective film is used which has an area such that concentrations of carbonic acid gas and of oxygen gas in a storage atmosphere gas composition in the vessel are of desired values assuming that a ratio of the amount of carbonic acid gas generated to the amount of oxygen consumed by the fruit, vegetable or flowering plant to be stored is set up to a value of from 0.3-to 0.8 and that the amount of the specific fruit, vegetable or flowering plant is from 10 to 50 %.
The feature of the above-described storage vessel of the present invention is that the area of the permselective film to be used which can give rise to a desired storage atmosphere gas composition for each of the green goods and fruits is determined by limiting the amount of storage in the store space to from 10 to 50 ~ so that transpiration or mixing of the storage atmosphere can take place appropriately.
The construction of the above-described storage vessel of the present invention is as a rule the same as 2 ~

has already been described above, and as the permselective film the same materials as described above can be used similarly. For example, films composed of polydimethyl-siloxane/polycarbonate copolymer, poly~4-methylpentene-1) or poly(2,6-dimethylphenyl ether) are used particularly preferably.
However, the above-described storage vessel of the present invention can be designed more concretely by specifying which green goods and fruits are to be stored concretely. For example, in the case where a pear as an objective of storage is to be stored at a low temperature, the above-described storage vessel is constructed such that the permselective film is made of polydimethyl-siloxane/polycarbonate copolymer and has a thickness of from 5 to 8~ m, and the proportion at which the perm-selective film occupies the vessel section is from 0.4 to 1 % of total surface area thereof, or such that the perm-selective film is made of poly-4-methylpentene-1 or poly~2,6-dimethylphenyl ether) and has a thickness of from 5 to 8~m, and the proportion at which the permselective film occupies the vessel section is from 0.5 to 5 % of total surface area thereof.
On the other hand, in the case where flowers for appreciation as an objective of storage are to be stored or housed at normal ambient temperature, the above-described storage vessel is constructed such that the permselective film is made of polydimethylsiloxaneJpoly-carbonate copolymer and has a thickness of from 5 to 8~m, and the proportion at which the permselective film oc-cupies the vessel section is from 0.4 to 4 % of totalsurface area thereof, or such that the permselective film is made of poly-4-methylpentene-1 or poly~2,6-dimethyl-phenyl ether) and has a thickness of from 5 to 8~m, and the proportion at which the permselective film occupies the vessel section is from 0.5 to 10 % of total surface area thereof.

By specifying the objective of storage, whole image of a suitable storage vessel becomes clear in the same manner as described above.
However, the storage vessel of the present invention may be prepared as one which has a relatively large window area which the permselective film occupies and means for covering the window, for example, a cover made of a material which is substantially impermeable to gases may be attached thereto detachably, which makes it possible to apply the storage vessel to various objectives to be stored.
Particularly, the storage vessel which has a plurality of vessel sections constructed by a perm-selective film is preferred because in this case the effective area of the permselective film can be adjusted easily by covering each of the plural windows with an impermeable material or removing it therefrom at will.
While the investigations by the present inven-tors as described above revealed that the values of p for various green goods and fruits are in a range of from 0.3 to 0.8, it has also been revealed that for specific green goods and fruits, the values of ~ change chronologically and increase gradually with lapse of storage period. For example, in the case of pears, the value of ~ was about 0.49 in an initial stage of storage, e.g. r up until day 4 or so, then increased gradually and was about 0.75 after 30 to 115 days. In almost the same time, the value of for sudachi changed from 0.43 to 0.86 while the value of for kabosu changed from 0.66 to 0.90.
Therefore, it is apparent that the storage vessel of which the area of one or more windows made of the permselective film can be changed as described above is desirable in order to continue to form a suitable storage atmosphere to cope with the variation of the values of ~ occurring with lapse of storage period as described above also in the case of storing specific green .,,, ~

2 a ~

goods and fruits.
The storage temperature is not limited particu-larly but is preferably from room temperature to about 0C. In order to prolong the storage period, lower tempe-ratures are preferred. Because the gas permeability ofthe permselective film, the amount of carbonic acid gas generated and that of oxygen consumed by green goods and fruits vary drastically depending on the temperature, it is required to take the storage temperature into full consideration when designing the storage vessel of the present invention, and it is recommended to provide means for changing the area of windows made of the permselective film in order to cope with the variation of the storage temperature.
In the storage vessel of the present invention, there may be introduced an ethylene absorbent for removing ethylene which is released by the fruits, vegetables or flowering plants while they are being stored and which accelerates their aging, or a hygroscopic sheet in order to positively prevent formation of water drops on the walls of the vessel. On the other hand, water may be allowed to coexist in the vessel in order to present transpiration of moisture from occurring during the storage. For example, a water-absorbing sheet sufficient-ly wetted is placed on the lower portion of the vessel, acushioning material is superimposed thereon, and the objective to be stored is placed on the cushioning material so that storage can be carried out without the sheet coming in a direct contact with the fruits and the like to be stored.
Examples Hereafter, the present invention will be ex-plained more concretely by way of examples.
Examples 1 and 2 and Comparative Examples 1, 2 and 3 Kabosu fruits harvested in Oita prefecture were used as an example of fruit.

2 ~

Bags for retaining freshness were made as fol-lows.
That is, a membrane of polysiloxane/polycarbo-nate having a thickness of 5~ m was used. The membrane was sandwiched between porous polyethylene membranes (thickness: 25~m, air permeation rate: 2.4 x 10 2 cc/cm2~sec/cmHg), and cut into a disc having an effective area of 2 cm ~together with margins of bonded portion).
The circumferential portion thereof was coated with an adhesive and the porous membrane and the membrane were bonded to each other.
On the other hand, a hole of 2 cm2 was formed in a laminate film ~width: 30 cm) comprised by polyethylene terephthalate and polyethylene, and the above-described sandwiched membrane sandwiched by the porous membranes was heat fused to the polyethylene side thereof.
The film was cut out so as to have a size of 28 cm x 33 cm, and three edges were heat fused to form a bag of a size of 25 cm x 30 cm. Separately, the bag was provided as attached thereto with a nozzle for collecting gases in the gas composition contained in the bag.
The membrane area was adjusted by number of bags attached to the bag.
After pretreating Kabosu fruits at room tempera-ture, 2,000 9 each of them were put into a bag and theopening of every bag was closed by heat fusion, and the bags were stored in a refrigerator at 5C. The packing ratio was 46 %.
The composition analysis of carbonic acid gas and oxygen gas in the storage bag was performed by gas chromatography. Separately, the Kabosu fruits used in the experiment were placed in a sealed vessel having a pre-determined volume and the amount of carbonic acid gas generated was determined to obtain 7.5 mg~Hr~kg at 5C.
In this connection, the gas permeation coef-ficients of polysiloxane~polycarbonate membrane at 5C

??~ 1~ r~-~
~V?~jJ~

were as follows:
Aqueous vapor: 183 x 10 cc.cm/cm2.sec.cmHg Carbonic acid gas: 6.6 x 10 8 cc.cm/cm2.sec.cmHg Oxygen: 1.7 x 10 8 cc.cm/cm2.sec.cmHg In comparative Example 1, experiments were carried out using bags produced in the same manner as in Example 1 except that a membrane of polysiloxane/poly-carbonate having a thickness of 50~ m was used as the permselective film.
In Comparative Example 2, experiments were carried out using bags produced in the same manner as in Example 1 except that the porous membrane used as a sup-port in Example 1 was used as it was but no permselective membrane was used.
The bags used in the respective examples and comparative examples were as shown in Table 2 below.
Table 2 Example/ Material of Area of Membrane Comparative Membrane ~Number of Membranes) Example Example 1 Polysiloxane/poly- 6 cm2 carbonate Example 2 Same as above 8 cm2 Comparative Polysiloxane/poly- 8 cm2 Example 1 carbonate (thickness: 50~m) Comparative Porous polyethylene 6 cm2 Example 2 membrane Comparative tOpen) Example 3 Figs. 5-a and 5-b plot measured values of storage period and of the gas composition of the storage 2~2~

atmosphere; a indicates chronological changes o~ the concentration of carbonic acid gas, and b indicates chronological changes of the concentration of oxygen relative to Examples 1 and 2 and Comparative Examples 1 and 2.
The acidity before the preservation experiments was 5.9 %, Brix was 8.0 %, and chlorophyll content was 12.4 mg/100 g.
After 90 day storage experiments, the storage bag was opened and the appearance and quality of the Kabosu fruits were evaluated. The results obtained are summarized in Table 3.
Table 3 Evaluation on Rabosu Fruits Run No. Acidity ~rix Chlorophyll Appearance and Others (%) (~) Content Example 1 4.8 7.4 8.3 mg Deep green maintained Example 2 4.2 7.5 7.9 Same as above Comparative 3.9 7.8 6.1 Colors maintained Example 1 with foreign odor Comparative 3.0 7.7 0.9 Yellowing, putre-Example 2 faction occurred from place to place Comparative 2.9 7.7 0.8 Yellowing, putre-Example 2 faction occurred from place to place ,, ~Examples 1 and 2) The Rabosu fruits retained the same appearance as before the storage and no problem was found in their quality. In the bags during storage, there occurred almost no adherence of drop of condensed water.
The concentrations of gases in a preservation state were kept substantially at optimal storage concentrations.
(Comparative Example 1) The Rabosu fruits produced h 1~ 2 ~ fJ i ~j foreign odor. Therefore, they had to be abandoned.
During the storage, a number of drops of water adhered inside the bag. No diffusion of aqueous vapor occurred.
(Comparative Example 2) The epidermis of each Kabosu fruit turned yellow. Upon cutting, it was observed that some of them had lost juice in sacks in the sarcocarp thereof, which indicated that transpiration of water was excessive. This is considered to be ascribable to the concentrations of gases being outside preferred range and to the decrease of humidity in the bag by the use of breathing porous membrane.
~Comparative Example 3) It was clearly demonstrated that storage was impossible even at low temperatures if kept in an open state.
Examples 3 and 4 and Comparative Examples 4r 5 and 6 Kabosu fruits harvested in Oita prefecture were used as an example of fruit.
Boxes for retaining freshness were made as follows.
That is, a membrane of polysiloxane/polycarbo-nate having a thickness of 2 .5~ m was used. The membrane was sandwiched between porous polyethylene membranes (thickness: 25~ m, air permeation rate: 2.4 x 10 2 cc~cm /sec/cmHg), and cut into a disc having an effective 25 area of 2 cm2 (together with margins of bonded portion).
On the other hand, a rectangular parallelopiped box of a size of 20 cm x 20 cm x 20 cm were produced with an acry-lic sheet (thickness: 5 mm), and a hole of 1 cm2 was formed on a side surface of each box, on which the above-described membrane was bonded (cf. Fig. 6). The boxesthus obtained were each provided as attached thereto with a nozzle for collecting gases in the gas composition in the box (not shown in Fig. 6).
After pretreating the Kabosu fruits at room temperature, 2 ~000 9 each of them were put into the respec-tive boxes and the opening of every box was closed, and r the boxes were stored in a refrigerator at 5C. The packing ratio was 25 ~.
The composition analysis of carbonic acid gas and oxygen gas in the storage boxes was performed by gas chromatography. Separately, the Kabosu fruits used in the experiment were placed in a sealed vessel having a pre-determined volume and the amount of carbonic acid gas generated was determined to obtain 7.5 mg/Hr/kg at 5C.
In this connection, the gas permeation coef-ficients of polysiloxane/polycarbonate membrane at 5Cwere the same as those described in Example 1.
In comparative Example 4, experiments were carried out using boxes produced in the same manner as in Comparative Example 3 except that a membrane of poly-siloxane/polycarbonate having a thickness of 50/~ m wasused as the permselective film.
In Comparative Example 5, experiments were carried out using boxes produced in the same manner as in Example 4 except that the porous membrane used as a sup-port in Example 4 was used as it was but no permselectivemembrane was used.
The boxes used in the respective examples and comparative examples were as shown in Table 4 below.

~ $ 2 Table 4 Example/ Material ofArea of Membrane Comparative Membrane (Number of Membranes) Example Example 3 Polysiloxane/poly- 3 cm2 carbonate Example 4 Same as above 4 cm2 Comparative Polysiloxane/poly- 4 cm2 Example 4 carbonate (thickness: 50~ m) Comparative Porous polyethylene3 cm2 Example 5 membrane Comparative (Open) Example 6 Figs. 7-a and 7-b plot measured values of storage period and of the gas composition of the storage atmosphere; a indicates chronological changes of the concentration of carbonic acid gas, and b indicates chronological changes of the concentration of oxygen relative to Examples 3 and 4 and Comparative Examples 4 and 5.
The acidity before the preservation experiments was 5.9 %, Brix was 8.0 %, and chlorophyll content was 12.4 mg/100 g.
After 90 day storage experiments, the storage bag was opened and the appearance and quality of the Kabosu fruits were evaluated. The results obtained are summarized in Table 5 below.

~ ~ 2 ~

Table 5 Evaluation on Kabosu Fruits Run No. Acidity Brix Chlorophyll Appearance and Gthers (~) (%) Content Example 3 4.7 7.6 8.2 mg Deep green maintained Example 4 4.1 7.5 8.0 Same as above Comparative 3.8 7.5 7.0 Colors maintained Example 4 with foreign odor C ~ arative 2.9 7.7 0.8 Yellowing, putre-Example 5 faction occurred from place to place Co~parative 3.0 7.8 0.7 Yellowing, putre~
Example 6 faction occurred from place to place (Examples 3 and 4) The Kabosu fruits retained the same appearance as before the storage and no problem was found in their quality. In the boxes during storage, there occurred almost no adherence of drop of condensed water.
The concentrations of gases in a preservation state were kept substantially at optimal storage concentrations.
(Comparative Example 4) The Rabosu fruits produced foreign odor. Therefore, they had to be abandoned.
During the storage, a number of drops of water adhered inside the boxes. No diffusion of aqueous vapor occurred.
(Comparative Example 5) The epidermis of each Kabosu fruit turned yellow. Upon cutting, it was observed that some of them had lost juice in sacks in the sarcocarp thereof, which indicated that transpiration of water was excessive. This is considered to be ascribable to the concentrations of gases being outside preferred range and to the decrease of humidity in the boxes by the use of breathing porous membrane.
(Comparative Example 6) It was clearly demonstrated that ~3 h i~
~ 28 -storage was impossible even at low temperatures if kept in an open state.
Example 5 Measurement on the amount of carbonic acid generated and the amount of oxygen consumed Green goods and fruits were housed in a sealed vessel having a given volume. The vessel and the green goods and fruits had been left to stand at a predetermined temperature for 24 hours in order to make their tempera-ture constant. After sealing, composition analysis ofcarbonic acid gas and oxygen gas in the sealed vessel was performed at a predetermined time interval by gas chromato-graphy.
From the changes of concentrations of carbonic acid gas and oxygen gas with lapse of time, the amount of carbonic acid gas generated and the amount of oxygen consumed were calculated. The results obtained are shown in Table 6.
Table 6 Green Goods Temperature Amount of 2 Value of and Fruits Consumed (C)(cc/kg/Hr) Apple 2 1.16 0.44 Japanese pear 5 2.16 0.50 ~uyugaki 5 1.1 0.36 Sudachi 5 4.5 0.46 Rabosu 5 3.5 0.43 Broccoli 18 73.8 0.56 Carnation 22 162.0 0.68 h ~ 2 i:~ 2 i Example 6 and ComParative Example 7 Six pears (variety: Housui) were put in an acrylic box of a size of 20 cm x 20 cm x 20 cm. Total weight was 3.0 kg. (The packing ratio was 38 %.) The amount of carbonic gas generated and that of oxygen gas consumed measured each at 5C were 1.08 cc/kg/Hr and 2.16 cc/kg~Hr, respectively.
On the window of the acrylic box was bonded a film of polydimethylsiloxane~polycarbonate copolymer (film thickness: about 10~m, oxygen permeation rate at 5C:
1.7 x 10 5 cc/cm2.sec.cmHg, carbonic acid gas permeation rate: 6.6 x 10 5 cc/cm2.sec.cmHg).
The size of the window was calculated according to the following formula:

2 2 2 .................................... (1) By setting up an objective concentration of oxygen to 6 %, and substituting respective values in the formula, the area (A) of the film was calculated to be A = 8.36 cm2. In Example 6, the material of the film was invariable, the concentration of carbonic acid gas was obtained according to the following formula (2):

X = - ~9 x xo ~ , Yo2 co2 The concentration of carbonic acid gas at equilibrium was calculated to be 2.0 %.
Then, storage of pears was performed actually using the polydimethylsiloxane~polycarbonate copolymer film, and the results on the change of gas concentrations were plotted in Fig. 8 attached hereto.
With lapse of time, the found data well coin-cided with the calculated data.
Results of the quality evaluation on pears 2 :~ ~

stored for 4 months are shown in Table 7.
Table 7 Taste Experiment Hardness Sugar Content (Rating Method) Sample (kg/cm2) (%) Sweetness Juice General ~A~t~e 3.6 Il.S4.5 4.0 4.6 storage 3.4 11.44.4 4.2 4.5 (4 months) :
Taste Experiment: Rating by 1 to 5 point evaluation;
higher point indicates better quality.
For comparison, assuming the amount of carbonic acid gas generated being 1.08 cc/kg/Hr was equal to the amount of oxygen consumed, the area of the film necessary for obtaining an oxygen concentration of 6 ~ using the same film was 4.5 cm .
Then, storage experiments were conducted for pears in the same manner as in Example 6 but at a film area of 4.5 cm2 and the changes in gas concentrations obtained are plotted in Fig. 9.
Pears after having been stored for the same period of 4 months produced foreign odor, and their inside turned blackish around the cores so that they were not good for eating; the general evaluation of taste experi-ment rated 1, 3.
Example 7 and Comparative Example 8 Storaqe ExPeriment for Apples The amount of oxygen consumed by apples at 2C
and values of ~ were as described in Table 1 and a storage atmosphere composition of 3 % of oxygen and 2 % of carbo-nic acid gas was selected as a target.
According to the formula (2),~ = 4 was obtain-ed, and hence poly(2,6-dimethylphenyl ether) (PPO; oxygen permeation coefficient: 1.0 x 10 9 cc.cm~sec.cm2.cmHg, ~ = 4.8) was selected as a material having a selectivity between carbonic acid gas and oxygen of nearly 4 and a good permeability.
The 5~m thick PPO film was prepared. Eight apples were put in an acrylic box of a size of 20 x 20 x 20 cm. The apples weighed 2730 9. (The packing ratio was 34 %.) The area of the film necessary for establishing 3 % oxygen aimed at was obtained by calculation according to the formula (1) to be 32 cm2.
lS Then, the concentration of carbonic acid gas was 2 %. Fig. 10 plots the changes of the concentrations of gases upon the storage experiment at 2C. Table 8 shows results of quality evaluation after 4 months. There was almost no decrease of the quality nor discoloration of the saprocarps.
Table 7 Taste Experiment Hardness Sugar Content (Rating Method) Sample (kg/cm2~ (~) Before S~Y~rcss Jhice ~3~ral Afttear9e 6.3 14.54.4 4.1 4.5 storage 6.1 14.14.2 4.2 4.3 I~ l Taste Experiment: Rating by points 1 to 5 evaluation;
higher point indicates better quality.

3 ~ i a For comparison, assuming the amount of carbonic acid gas generated being 0.510 cc/kg/Hr was equal to the amount of oxygen consumed, the area of the film necessary for obtaining an oxygen concentration of 3 % using the same film was 14 cm2.
Accordingly, storage experiments were conducted in the same manner as in Example 7 but at a film area of 14 cm with 5~v~m PPO film and the changes in gas con-centrations obtained are plotted in Fig. 9.
Fig. 11 shows results of atmosphere gas composi-tion analysis. As a result of the quality evaluation after storing at 2C for 4 months, the hardness decreased to 4.2 kg/cm2, the sarcocarps discolored to brown and were unable to eat.
Example 8 and Comparative Example 9 A bag of size of 12.5 cm x 50 cm was made of a gas barrier film composed of a laminate of polyethylene and nylon, and a part of the bag at an area of 10 cm2 was cut off. A polysiloxane/polycarbonate copolymer membrane tthickness: 8~m, sandwiched by porous pp membranes serving as a protective material) was attached to the cut-off portion.
Four Carnations ~variety: Nora) weighing 65 9 collected just after efflorescence were put in the bag, and the bag was sealed after purging air as much as pos-sible tpacking ratio: 13 %). It was placed in a room at 22C. The amount of carbonic acid gas generated and that of oxygen consumed by the carnations at 22C were 110 cc/hr/kg and 162 cc/hr/kg, respectively.
Table 8 shows the concentrations of gases in the bag.
For comparison, the same procedures were repeat-ed except that carnations were housed in a bag made of the gas barrier film only. This is shown as Comparative Example 9 in Table 8.
When the bag was opened after 1 week, the 2~2~
, ~,..

flowers bloomed a little more but their color remained unchanged, retaining the deep pink color.
On the contrary, in Comparative Example 9, the flowers lost the pink color and turned whitish. The flowers were placed in a room at the same temperature of 22C, after being put in a pot. They showed almost no change and were well appreciable even after 1 week.
On the other hand, those put in a pot in an open state just after the collection withered after 1 week, and the flowers became smaller, and did not worth apprecia-tion.
Table 8 Day lapsed Example No.
1 Day 2Days 3Days SDays 9Days _ Example 8 CO2 2.6% 4.1% 5.0% 5.3~ 5.9%

215.7%10.9%10.1%8.1% 8.0%
ComparativeCO2 3-9% 8.3%11.2% 13.5% 16.2%
Example 9 _ 29.7%4.7% 2.7% ~ 0.5 Example 9 On a bag prepared in the same manner as in Example 8 using a gas barrier film composed of a laminate of polyethylene and nylon was attached by heat fusion a film (film thickness: S~m, laminated on a porous mem-brane support made of polypropylene and the membrane was covered thereon with a porous membrane made of a protec-tive material) of poly-4-methylpentene (MX-002, produced by Mitsui Petrochemical Co., Ltd.).

2 ~ ~J .~

Four Carnations (variety: Tanga) collected just after efflorescence were put in the bag, and the bag was sealed after purging air as much as possible (packing ratio: 13 %). It was placed in a room at 15C and opened after 2 weeks. The concentrations of gases at week 1 and week 2 were 6.3 % and 7.6 ~, respectively for carbonic acid gas, and 6.8 % and 5.9 %, respectively, for oxygen.
After 2 weeks, the flowers were under the condi-tions that efflorescence of the flowers proceeded a little more but their red color did not change. Thereafter, the flowers were left to stand at the same temperature of 15C
for 10 days but their sizes remained unchanged and they were well appreciable. On the other hand, when the flowers were put in a pot just after the collection and the pot was placed in a room at 15C, they were appreci-able for 1 week but on 10 days the flowers drooped and withered and were not appreciable.
The amount of carbonic acid gas generated and that of oxygen consumed by the carnations at 15C were 73.6 cc~hr~kg and 103.7 cc/hr/kg, respectively.
Example 10 A film of poly-4-methylpentene-1 (thickness:
5~ m) was used.
The film was inserted between porous polypro-pylene membranes.
A rectangular parallelopiped box of a size of 20 cm x 20 cm x 20 cm made of an acrylic sheet was formed with 2 windows on a side surface thereof, and the above-described film was bonded thereto.
Six pears ~variety: Housui) weighing 3,000 9 were put in the box, which was stored in a cold storage room at 5C for 5 months. ~The packing ratio was 38 %.) Also, another box provided with the film was prepared in which an ethylene absorbent was introduced and wetted water-absorbing sheet was placed on the bottom, and pears were stored therewith similarly.

n~(~,r?~,~ I`' ' : ~J ~ ~3 The concentrations of gases in the box were as shown in Table 9.
For comparison, storage in an open state, storage in a polyethylene bag (thickness: 50~m), and storage in a polyethylene bag containing an ethylene absorbent and wetted water-absorbing sheet were also carried out. The results obtained are shown in Tables 9 and 10.
Table 9 Period Sa~le ~ 1 Nonth 2 Nonths 3 Nonths 4 Nonths S !bnths Example 10 C02 3 0 3.8 3.7 3.8 3.9 2 8.1 7.0 6.7 6.6 6.8 Eu~$~e 10 C02 2.9 3.8 3.9 3.7 4.0 absorbent and _ sheet 2 8.2 7.1 6.9 6.5 6.7 Comparison C02 4.7 5.1 5.9 6.8 7.1 ~Polyethylene) 2 4.5 2.7 1.8 0.9 0.8 h Table 10 Quality Evaluation of Stored Pears Taste ~periment Sample Hardness Sugar Content Nature of Sweetness Foreign (kg/cm2) (%) Sarcocarp Taste/Cdor In itial Value 3.9 11.5Hard No Example 10 3.5 11.4Hard Go~ No Example 10 3.5 11.5Hard Good No (+ Ethylene absorbent and water-absorb-ing sheet) a~
C~ re~e 2 6 12 9Soft Poor L

Example 3.3 10.9Hard Poor Yes bagyethylene ~

In the storage in an open state, the pears dried up and became smaller, thus losing commercial value. The pears stored in the polyethylene bag gave alcoholic odor and showed browning of sarcocarps, thus losing commercial value.
The pears stored in this example were fresh-looking and sweet, thus retaining sufficient commercial value, even after 5 months.
The storage box in which the ethylene absorbent and wetted water-absorbing sheet were placed like the box without them enabled storage. Upon taste examination, a little more than half the panel members judged the stored h~

pears stored in the bag containing the ethylene absorbent and wetted water-abosorbing shleet to be better than those stored in the bag without them, and thus some effects on storage were observed.
Example 11 A film of poly-4-methylpentene-1 (Type MX-002, produced by Mitsui Petrochemical Co., Ltd.) having a thickness of 5~ m was used. This film was inserted bet-ween polypropylene unwoven fabrics.
A cube of a size of 20 cm x 20 cm x 20 cm was made using an acrylic sheet (thickness: 5 mm), and two windows of 90 cm2 were formed on a side surface thereof, and the above-described film was bonded to the windows.
In the box, 850 g of rape ~variety: Kouyou ichigou) was put and the bag was sealed ~the packing ratio was 11 ~), and stored at 15C.
Table 11 shows the changes of the concentrations of gases during the storage.
Changes of general freshness and of internal components of rape are shown in Tables 12 and 13, respect-ively. Comparison was open storage at 15C.
In the case of open storage at 15C, limitation for storage was 2 days while in this example, storage was possible for 8 days.
At 15C, the amount of carbonic acid gas gene-rated and that of oxygen consumed by rape were 29 cc/Hr/kg and 36.7 cc/Hr/kg, respectively.

r-~ 38 --Table ll Change of Gas Concentrations on Storage of Rape Gas Period 1 Day 3Days SDays 8Dsys C2 1.4% 3.1% 4.4% 4.5%
2 13.5% 8.4% 7.2~ 6.1%

Table l2 General Freshness Change (Index) on Storage of Rape Period Sample O Day 2Days 4Days 6Days 8Days Example 11 3.8 3.4 3.0 Comparative 3.8 3.0 1.8 1.4 Example 4: Freshness just after harvest;
3: Freshness decreased slightly, marketable:
2: Freshness decreased apparently, unmarketable but edible; and l: Freshness decreased remarkably, unsuitable for food ~ ~J 2 Table 13 Change of Components (Chlorophyll Content) on Storage of Rape Period Sample 0 Day 6Days 8Days Example 11 120.2 58.1 Comparative 120.2 91.3 84.2 Example Example 12 In the same Manner as in Example 11, a poly-4-methylpenetene-l film tthickness: 5~ m) and an acrylic box (20 cm x 20 cm x 20 cm) were prepared.
Two windows (each 80 cm2) were formed, and the film was bonded thereto. In the box, 1,000 9 of plums (variety: Shirokaga) were put ~pacing ratio: 13 %), and the bag was sealed and stored at 5C.
Table 14 shows changes in the concentrations of gases during to storage.
Plums must not undergo yellowing. Table 15 shows changes in the color of the fruits. In the storage in air, yellowing was observed after 5 days while in this example almost no yellowing was observed even after 15 days, thus retaining sufficient commercial value.
The amount of carbonic acid gas generated and that of oxygen consumed by the plums were 22 cc/Hr/kg and 30 cc/Hr/kg, respectively.

h V ~ ~3 Table 14 Change of Gas Concentration on Storage of Plums (%) Gas Perio 1 Day 3Days 7Days 1 ODays ~1 SDays C2 1.8 3.8 4.3 4.5 4.8 ~2 13.2 7.5 4.5 4.3 4.3 Table 15 Change of Fruit Color on Storage of Plums L.¦ 9/6 ¦

Period Sample O Day ¦5Days ¦lODays ¦15Days Example 12 97.7 106.2 106.8 122.4 Comparison 97 . 7 17 5 . 2 1 83 . 4 2 83 . 2 Comparison showed yellowing on day 5.

Example 13 Storage Experiment for Sudachi Fruits The amount of oxygen consumed by apples at 5C
and values of~ were as described in Table 16 and a storage atmosphere composition of 4 % of oxygen and 3 ~ of carbonic acid gas was selected as a target.
According to the formula (2) ,d~ = 2.6 was ob-tained. However, no film material is present which has such a small ~ and hence poly-4-methylpentene-1 was selec-ted as a material which has a relatively small d~and a , 2 good permeability.
Oxygen permeation 9 2 rate at 5C : 1.12 x 10 cc.cm/cm .sec.cmHg Carbonic acid gas 9 2 permeation rate : 3.54 x 10 cc.cm/cm .sec.cmHg at 5C

Nitrogen permea- 9 2 tion rate at 5C : 0.26 x 10 cc.cm/cm .sec.cmHg The 5~m thick poly-4-methylpentene-1 (type MX-002) film was prepared.
In an acrylic box of a size of 20 cm x 20 cm x 20 cm were put 2,000 9 of Sudachi fruits which had been pretreated for 3 days. (The packing ratio was 25 %.) The area of the film necessary for establishing 4 % oxygen aimed at was obtained by calculation according to the formula ~1) to be 82 cm2.
Then, when the poly-4-methylpentene-1 was used, the concentration of carbonic acid gas at equilibrium with an oxygen concentration of 4 % was 2.8 % according to the formula ~2).
To add, when the value of ~is obtained accord-ing to the formula (2) at ~ = 1 and aiming at oxygen concentration of 4 ~ and carbonic acid gas concentration of 3 %,~/ = 5.7 was obtained, which means that it was necessary to select a film material having a higher perm-selectivity to carbonic acid gas and oxygen. Table 16 plots the changes of the concentrations of gases during the storage. Comparisons were stored in air and in a 20~vm thick polyethylene bag (size: 38 cm x 26 cm, Weight of Sudachi fruits: 2,000 9).
Table 17 shows results of quality evaluation on the stored Sudachi fruits.
It is a point of the storage of Sudachi fruits to retain their greenness and to prevent the occurrence of those having sports on their skin (damaged fruits).
The storage in air for comparison caused yellow-h S.~6 2 s3 ~ ~ 3 -- 42 --ing after 4 months, thus already losing commercial value.
The storage in a thin polyethylene bag enabled retaining greenness but in this case almost all the fruits suffered the occurrence of brown sports on their skin, thus losing commercial value.
On the contrary, the storage according to this example enabled storage for 6 months.
Table 16 Change of Gas Concentrations on Storage of Sudachi Fruits ~%) Number of Months (M) ; Sample 1 M 2 M 3 M l4 M 5 M 6 M

Example 13 CO2 2.8 2.9 3 0 3.2 _ _ 2 4.3 4.3 4.1 4.3 4.0 4 2 Comparison CO2 4.1 4.2 4.8 5.2 5.8 6.9 Ethylene Bag _ _ 2- 3.2 3 4 2.6 2.4 2.5 2~i~i3f..i_~

C OJ ~ N _ _, _ O r--I ~ N ~D N ~1 (S~
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U~ O ~ ~ N N ~ ~ g ~
.~ .U~ O ~ U) U~ ~1 O ~-1 ~ ~ O ~ ~ CO l_ ~ 1 .q ~r ~J In ~ O ~`I
~ ~ _ _ U~ r~ ~ ~: _l c~ c~ Ll~ O
~ O ~ V~ N ~ ~ N ~
~1 u~ 5~: o~ c~ o. a~ o ~0 ~ d' _1 U~ In C~l ~0 ~0 _ _ 0 ~ 9~ dP U~ CO O O
H ~ O ~ IS~ ~
~ .~ rY
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~0 ~o 1~ dP _1~

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Claims

- 45 -

1. A storage vessel for fruits, vegetables or flowering plants comprising a vessel section a part of which includes a permselective film which is permselective to carbonic acid gas and oxygen gas, wherein said perm-selective film has a thickness of no higher than 30µm.

2. A storage vessel as claimed in Claim 1, wherein said gas permselective film has a thickness in a range of from 0.05 to 10µm.

3. A storage vessel as claimed in Claim 1, wherein said gas permselective film is supported on a porous support which is substantially non-selective to carbonic acid gas and oxygen gas.

4. A storage vessel as claimed in Claim 1, wherein said gas permselective film is protected with a breathing protective material having an air resistance by smaller than 1/20 time as high as an air permeation resis-tance of said film.

5. A storage vessel as claimed in Claim 1, wherein said gas permselective film has a ratio of permea-tion rate of carbonic acid gas to that of oxygen gas of from 2 to 10.

6. A storage vessel as claimed in Claim 1, wherein said gas permselective film has a ratio of permea-tion rate of aqueous vapor to that of oxygen gas of from 10 to 500.

7. A storage vessel as claimed in Claim 1, wherein said permselective film heat fused constitutes a part of said vessel section.

8. A storage vessel as claimed in Claim 1, wherein said vessel is in a form of a bag or box.

9. A storage vessel as claimed in Claim 1, wherein said part of said vessel section constituted by said permselective film exists in plural number.

10. A storage vessel for storing a specific fruit, vegetable or flowering plant, comprising a vessel section, a permselective film which is permselective to carbonic acid gas and oxygen gas and occupies a part of said vessel section, and an atmosphere gas composition contained in said vessel, wherein said permselective film has an area such that concentrations of carbonic acid gas and of oxygen gas in said storage atmosphere gas composi-tion in said vessel are of desired values assuming that a ratio of an amount of carbonic acid gas generated to an amount of oxygen consumed by said fruit, vegetable or flowering plant to be stored is set up to a value of from 0.3 to 0.8 and that an amount of said specific fruit, vegetable or flowering plant is from 10 to 50 %.

11. A storage vessel as claimed in Claim 10, wherein said permselective film is comprised by poly-dimethylsiloxane/polycarbonate copolymer.

12. A cold storage vessel for pears as claimed in Claim 10, wherein said permselective film is made of polydimethylsiloxane/polycarbonate copolymer having a thickness of from 5 to 8µm, and a proportion in which said permselective film occupies is from 0.4 to 1 % of total surface area of said vessel section.

13. A room temperature storage vessel for flowers and vegetables as claimed in Claim 10, wherein said permselective film is made of polydimethylsiloxane/-polycarbonate copolymer having a thickness of from 5 to 8µm, and a proportion in which said permselective film occupies is from 0.4 to 4 % of total surface area of said vessel section.

14. A storage vessel as claimed in Claim 10, wherein said permselective film is comprised by poly-4-methylpentene-1 or poly(2,6-dimethylphenyl ether).

15. A cold storage vessel for pears as claimed in Claim 10, wherein said permselective film is comprised by poly-4-methylpentene-1 or poly(2,6-dimethylphenyl ether) having a thickness of from 5 to 8µm, and a propor-*
tion in which said permselective film occupies is from 0.5 to 5 % of total surface area of said vessel section.

16. A room temperature storage vessel for flowers and vegetables as claimed in Claim 10, wherein said permselective film is comprised by poly-4-methyl-pentene-1 or poly(2,6-dimethylphenyl ether) having a thickness of from 5 to 8µm, and a proportion in which said permselective film occupies is from 0.5 to 10 % of total surface area of said vessel section.

17. A method for storing fruits, vegetables or flowering plants in a storage vessel including a vessel section, a permselective film which is permselective to carbonic acid gas and oxygen gas and occupies a part of said vessel section and an atmosphere gas composition, wherein concentrations of carbonic acid gas and of oxygen gas in said storage atmosphere gas composition in said storage vessel is determined by setting up a ratio of an amount of carbonic acid gas generated to an amount of oxygen consumed by fruits, vegetables or flowering plants to be stored to a value in a range of from 0.3 to 0.8 and determining based thereon an area of said permselective film to be used and an amount of said fruits, vegetables or flowering plants to be stored.

18. A method as claimed in Claim 17, wherein said concentration, WCO2, of carbonic acid gas and said concentration of oxygen gas, WO2, are determined according to a relationship represented by formula:

wherein C: unit conversion coefficient = 3.655 x 10-6, G: the amount of oxygen consumed by the fruit, vegetable or flowering plant, A: the area of the permselective film (cm2), B: the amount of the fruit, vegetable or flower-ing plant to be packed (kg), KO2 : the oxygen permeation rate of the perm-selective film (cc/cm2/sec/cmHg), ? : the gas selectivity of the permselective film (= carbonic acid gas permeability/oxygen permeability), ?: the amount of carbonic acid gas generated by the fruit, vegetable or flowering plant/amount of oxygen consumed by the fruit, vegetable or flowering plant (= 0.3 to 0.8), YO2: the concentration of oxygen in the air, YCO2: the concentration of carbonic acid gas in the air, WO2: the concentration of oxygen gas in the atmosphere gas composition, and WCO2: the concentration of carbonic acid gas in the atmosphere gas composition.