FR2531042A2 - Device for storing products subject to dehydration in a refrigerator. - Google Patents

Abstract

The device for storing, in a refrigerator, products 105 subject in particular to dehydration and/or sensitive to the presence of water, comprises an outer enclosure 100 which comprises an inner compartment 102 to receive these products 105. The outer enclosure 102 comprises a membrane 108 which is impermeable to water vapour but permeable to oxygen, carbon dioxide and ethylene. Use for preventing, in particular, the loss of oxygen and accumulation of carbon dioxide inside the enclosure for storing products such as fruit and vegetables.

Description

The main patent describes a device for keeping, in a refrigerator, products sensitive to dehydration and / or to the presence of water, such as fruits and vegetables, this device comprising a substantially hermetic enclosure which comprises an inner compartment for receiving these products
This compartment is separated from the outer enclosure by a wall permeable to water vapor, at least the portion of this wall located above the products and which could have been crossed by gravity by drops of water condense being realized in a material impermeable to these drops of water
The water vapor that emanates from the products placed in the inner compartment of the device, passes through the wall of this compartment and condenses on that of the outer enclosure, which allows to obtain quickly inside the enclosure, a vapor pressure equilibrium with that of the products Thus, the process of dehydration of these, is quickly stopped
Moreover, it avoids any contact between these products and the condensed water, since at least the portion of the wall of the compartment which is located above the products and which could have been traversed by gravity by drops of condensed water is made of a material impervious to these drops of water. This also avoids the rotting of the products contained in the inner compartment of the device.

-The device described in the main patent is not completely satisfactory because it does not fully prevent fermentation and physiological diseases of products such as fruits and vegetables stored in the enclosure qazeux
Indeed, in the absence of exchange / with the outside one finds, inside the compartment, where are arranged fruits and vegetables, an increase of the carbon dioxide and ethylene content and a decrease of the oxygen content .

 The accumulation of carbon-i gas in the atmosphere surrounding the products and the deficiency of this oxygen atmosphere favors the fermentation of the products.

Similarly, the presence of ethylene favors certain physiological diseases
The purpose of the present addition is to improve the preservation device described in the main patent in order to avoid the harmful effects due to the confinement of the products inside the enclosure.

 According to the addition, this device is characterized in that the outer enclosure comprises a membrane impermeable to water vapor, but permeable to oxygen, carbon dioxide and ethylene.

 This membrane allows: thus a gas exchange between the inside of the enclosure and the outside environment.

This membrane prevents the passage of water vapor, so that as in the case of the device described in the main patent, it avoids dehydration of the products contained in the enclosure.

 On the other hand, since this membrane allows the passage of carbon dioxide, oxygen and ethylene, the concentration of these gases in the atmosphere surrounding the products is maintained at an optimum value.

 This membrane makes it possible in particular to avoid the accumulation of carbon dioxide and ethylene as well as the depletion of oxygen inside the leniency, which are at the origin of the harmful effects indicated previously.

 According to an advantageous version of the addition, the membrane is made of a material whose permeability is for carbon dioxide, of between 1 and 10 × 10 -6 cm 3 cm -2 sec-1 torr-1, and for oxygen between 0 , 1 and 1 x 10-6cm3 cm-2second -1 torr-1.

 These values of permeability can be obtained by using a membrane comprising a layer of dimethyl polysiloxane applied to a polyamide support layer.

 Other features and advantages ofaddition will appear in the following description.

In the accompanying drawings:
Figure 1 is a perspective view and in longitudinal section of a conservation chamber, consistent with the addition;
- Figure 2 is a sectional view along the plane II-II of Figure 1;
FIG. 3 is an enlarged view of detail III of FIG. 2;
FIG. 4 is a graph showing the evolution, in time, of oxygen and carbon dioxide contents within an addition-compliant enclosure.

 In the embodiment of FIG. 1, the storage device intended to be placed in a refrigerator comprises an outer enclosure 1-00 hermetically closed by a cover 101. This enclosure 100 encloses a compartment 102, whose bottom and side faces The upper portion of this compartment 102 is closed by a water vapor permeable membrane 104 that is emitted by the product 105, such as vegetables or fruits 7 contained in the compartment 102. The membrane 104 however, it is impermeable to water which condenses on the outer face of this membrane 104.

This device thus makes it possible to avoid dehydration
product 105, while avoiding any contact
between it and the condensed water which could have favored the rotting of the product.

In accordance with this addition, one
106 of the lateral faces of the outer enclosure 100, comprises an opening 107 closed by a membrane 108, impervious to water vapor, but permeable to oxygen, carbon dioxide and ethylene.

In the embodiment shown (see figures
1 and -the membrane 108 is protected externally by a perforated wall such as a grid 109.

This membrane 108 is constituted (see FIG. 3) by a layer 110 of dimethyl polysiloxane applied on a support layer 111, for example made of fabric
of polyamide.

The layer 110 of dimethyl polysiloxane has a thickness of between 50 and 100 microns. Its permeability is, for carbon dioxide equal to 3.2 x 10-6 cm3
cm-2 second-1 torr-1, for oxygen equal to 0.6 x 10-6
cm3 cm-2 seconds-1 torr-1 and 1.3 x 10-6 cm3 cm-2sec-1 torr-1 for
ethylene.

The layer 110 of dimethyl polysiloxane is also permeable to volatile vapors légeis, such as ethylene. On the other hand, it is impervious to water vapor. The aforementioned values of the permeability are not critical. Indeed, excellent results are obtained when the permeability of the membrane 108 is between the following limits
For carbon dioxide; 1 to 10 x 10-6cm3
cm-2 seconds -1 torr-1 -6 3 -2
For oxygen: 0.1 to 1 x 10- @ cm @ cm-second torr 1.

The surface of the membrane 108 depends on the weight,
the nature and in particular the respiratory activity of the fruits and vegetables stored in the building 102.

 In the case of fruits and vegetables usually preserved, it is advantageous for the surface of the membrane 108 to be between 5 and 100 cm 2 / kg of product.

In the table below, by way of example, the volumes of CO 2 released for some fruits and vegetables preserved at 6 ° C. and the areas required for the membrane 108 are indicated in order to obtain optimal exchange conditions with the product. outside.

<Tb>

<SEP> Surface <SEP> of <SEP> membrane
<tb><SEP> Products <SEP> ml <SEP> of <SEP> CO <SEP> clear <SEP> (108) <SEP> required <SEP> in
<tb><SEP> by <SEP> h. <SEP> ee <SEP> by <SEP> kg <SEP> em2 / kg <SEP> of <SEP> product
<tb><SEP> Raisin <SEP> 1.6 <SEP> to <SEP> 3 <SEP> 5 <SEP> to <SEP> 7
<tb><SEP> Plum <SEP> 2.1 <SEP> to <SEP> Y, 6 <SEP> 6 <SEP> to <SEP> 12
<tb><SEP> Tomato <SEP> mure <SEP> 3 <SEP> 8
<tb><SEP> Cucumber <SEP> 3.5 <SEP> to <SEP> 7.4 <SEP> 9 <SEP> to <SEP> 20
<tb> Melon <SEP> 4,4 <SEP> 12
<tb> Strawberry <SEP> 6.9 <SEP> 18
<tb><SEP> Bean <SEP> green <SEP> 21.3 <SEP> to <SEP> 26.4 <SEP> 56.7
<Tb>
In order to be able to modify the surface of the membrane 108, depending on the nature and / or the weight of the product to be preserved, it is advantageous to apply the membrane to a plurality of small distributed openings.
on one or more faces of the outer enclosure 100, these openings being more or less closed following
the product used.

 The results of the comparative tests set out below illustrate the effects and technical advantages of the device according to the addition.

Example 1
The table below shows the oxygen and CO 2 concentrations that were measured in the atmosphere in which eight fruits and vegetables were stored for eight days.

<SEP><SEP> Exposure in <SEP> O2 <SEP> and <SEP> CO2 <SEP> of <SEP> Atmospheres <SEP> of
<tb><SEP> confinement
<tb><SEP> Products <SEP> Enclosure <SEP> closed <SEP> | <SEP> Enclosure <SEP> according to <SEP> addi Enclosure <SEP> terminated <SEP> Enclosure <SEP> according to <SEP> a @@@ -
<tb><SEP> tightly <SEP> tion <SEP> provided <SEP> with a
<tb><SEP> membrane <SEP> 108
<tb> O2 (%) <SEP> CO2 (%) <SEP> O2 (%) <SEP> CO2 (%)
<tb><SEP> Mandarin <SEP> 1.0 <SEP> 30.7
<tb><SEP> Endive <SEP> 0.3 <SEP> 19.7
<tb><SEP> Tomato <SEP> 0.5 <SEP> 17.6 <SEP> 10 <SEP> 5
<tb><SEP> Mast <SEP> 12.1 <SEP> 7.4
<tb><SEP> Fungus <SEP> 0.2 <SEP> 25.7
<tb><SEP> Grape <SEP> 0.2 <SEP> 27.6
<tb><SEP> Melon <SEP> 1.3 <SEP> 34.1 <SEP>
<tb><SEP> Melon <SEP> 0.17 <SEP> 29.4 <SEP> 9 <SEP> 3
<tb><SEP> Bean <SEP> green <SEP> 1.4 <SEP> 39.9
<tb><SEP> Bean <SEP> green <SEP> 0.5 <SEP> 46 <SEP>
<tb><SEP> Bean <SEP> green <SEP> 0.3 <SEP> 37 <SEP> 7.4 <SEP> 3.6 <SEP>
<tb><SEP> Pear <SEP> 0.1 <SEP> 34.4 <SEP>
<tb><SEP> Pear <SEP> 1.4 <SEP> 22.2
<tb><SEP> Pear <SEP> 0.8 <SEP> 17.5 <SEP> 3.3 <SEP> 5.9
<Tb>
In the case of products stored in a hermetically sealed enclosure, and devoid of membrane 108 permeable to oxygen and carbon dioxide, it is found after eight days that the oxygen content is much lower than that of a normal atmosphere and carbon dioxide levels are significantly higher than normal.

Fruits and vegetables, stored in these conditions
have reached a stage of fermentative activity
rendering it unfit for consumption.

In the case of products stored in a
enclosure provided, in accordance with the addition of a membrane
108 permeable to oxygen and carbon dioxide,
that the oxygen and carbon dioxide contents are
close to those of a normal atmosphere.

Products stored under these conditions,
have kept their original fresh appearance, and have remained
perfectly edible.

Example 2
The following example illustrates the effectiveness of selectively permeable membranes in the control of the gaseous atmosphere:
Analysis of the gaseous atmosphere surrounding placed products
at 50 C in hermetic boxes

<tb><SEP> 3 <SEP> days
<tb><SEP> After <SEP> 4,5 <SEP> Cou- <SEP> just <SEP> after
<tb> days <SEP> vircle <SEP> after <SEP> iron-have <SEP> or
<tb><SEP> of between <SEP> open <SEP> setting <SEP> of <SEP> green <SEP> and
<tb><SEP> setting <SEP> 2 <SEP> mn <SEP> cover <SEP> closed <SEP>
<tb><SEP> cover
<tb><SEP> Box <SEP> no <SEP> Pears <SEP>% 02 <SEP> 8.71 <SEP> 19.91 <SEP> 10.17
<tb><SEP> equipped <SEP> with
<tb><SEP>% CO2 <SEP> 9.94 <SEP> 0.61 <SEP> 10.76
<tb><SEP> membrane
<tb> silicone
<tb> Beans
<tb>% O2 <SEP> 5.46 <SEP> 18.90 <SEP> 4.06
<tb> green
<tb>% CO2 <SEP> 11.27 <SEP> 1.14 <SEP> 14.78
<tb> Box <SEP> equipped with <SEP> Pears <SEP>% O2 <SEP> 11.29 <SEP> 20.41 <SEP> 12.01
<tb> of <SEP> membrane
<tb>% CO2 <SEP> 5.01 <SEP> 0.10 <SEP> 5.69
<tb><SEP> Beans
<tb><SEP>% O2 <SEP> 11.86 <SEP> 19.77 <SEP> 11.75
<tb> vcerts
<tb><SEP>% CO2 <SEP> 3.18 <SEP> 0.33 <SEP> 3.25
<Tb>
It can thus be seen that in a few days of storage in a hermetic enclosure, the gaseous atmosphere becomes asphyxiant for the products, while the presence of a membrane 108 with selective permeability prevents this risk.

Example 3
The curves shown in FIG. 4 represent the evolution of the oxygen and CO 2 contents, as a function of time t in a day, in an enclosure according to the addition equipped with a membrane 108, and enclosing pears.

 The membrane 108 was masked tightly during the first days and then was unmasked. Arrow F indicates the date the membrane was unmasked.

 It can be seen that as long as the membrane 108 is masked, the oxygen content decreases rapidly and, on the other hand, the carbon dioxide content increases.

 When the membrane 108 is unmasked, the carbon dioxide content decreases very rapidly the first days. This content then continues to decrease but at a slower rate. In addition, the oxygen content increases gradually.

The results of the aforementioned tests thus show that the membrane 108 of the enclosure in accordance with the addition makes it possible to maintain in the compartment for the conservation of fruits and vegetables an atmosphere of optimum composition, avoiding
thus the degradation of these, in the presence of a
atmosphere too rich in CO2 and too low in oxygen.

The membrane 108 allows at the same time,
limit the ethylene content and thus avoid -some physiological diseases responsible for the degradation
fruits and vegetables.

Moreover, since the membrane
108 is impervious to water vapor, the device according to the addition avoids, as the one described in the main patent, the dehydration of the products and their decay in the presence of condensed water.

 Of course, the addition is not limited to the examples just described and can be made to these many modifications, without departing from the eadre of the invention.

 Thus, the membrane 108 may be made of a material other than dimethyl polysiloxane, provided that this material is permeable to oxygen, carbon dioxide and ethylene and impervious to water vapor. Some plastics such as high density polyethylene have these properties.

Claims (9)

 1. Device according to any one of the claims of the main patent, for keeping in a refrigerator sensitive products, especially dehydration and / or the presence of water, comprising an outer enclosure (100) which has an inner compartment (102) for receiving the products (105), characterized in that the outer enclosure comprises a membrane (108) impervious to water vapor, but permeable to oxygen, carbon dioxide and ethylene.  2. Device according to claim 1, characterized in that the membrane (108) is of a material whose permeability is for carbon dioxide, between 1 and 10 x 10-6cm3 cm-2 second 1 torr1, and for oxygen between 0.1 and 1 x 10-6 cm3 cm-2 seconds -1 torr 1.  3. Device according to any one of claims 1 or 2, characterized in that the membrane (108) comprises a layer (110) of dimethyl polysiloxane applied on a support layer (111) of polyamide.  4 Device according to claim 39 characterized in that the layer (110) of dimethyl polysiloxane has a thickness of between 50 and 100 microns.  5. Device according to any one of claims 1 or 2, characterized in that the membrane (108) is made of high density polyethylene.  6. Device according to any one of revendicati-ons 1 to 5, characterized in that the surface of the membrane (108) is between 5 and 100 cm2 / kg of product to be preserved.  7. Device according to any one of claims 1 to 6, characterized in that the membrane (10-8) is applied to an opening (107) formed on a side face of the outer housing (100).  8. Device according to any one of claims 1 to 6, characterized in that the permeable membrane (108) is applied to a plurality of openings distributed over one or more faces of the outer enclosure (100).  9 Device according to any one of claims 7 or 8, characterized in that the or openings (107) are protected externally by a perforated wall (109).  108 Apparatus according to any one of claims 7 to 9s characterized in that it comprises shutters for closing said openings (107).