1. PURPOSE
[0001] The present invention relates to the packaging of perishable items such as vegetables
and fruits, in particular to the means for controlling gas composition in the atmosphere
inside the container and facilitating manual closure, for instance, of the packing
without using automatic techniques such as heat sealing.
2. DESCRIPTION OF PRIOR ART
[0002] Some perishable products, such as vegetables and fruits, continue their ripening
and ageing process after being harvested. During ripening and ageing, the product
undergoes a respiratory process characterized by oxygen absorption and the release
of carbon dioxide and ethylene. Additionally, the product transpires moisture, reducing
its weight. Decreasing respiration and transpiration in the packaging is critical
to extend the green life of perishable products. Another problem associated with uncontrolled
respiration is reaching a high concentration of carbon dioxide in the atmosphere inside
the packaging, which can affect the organoleptic properties of the perishable product.
[0003] Prior art includes some alternatives for the control of respiration and transpiration
in packaging perishable products. These technologies include the following: transportation
in refrigerated containers; hypobaric packaging, containers with devices that remove
ethylene; active packaging that traps oxygen, carbon dioxide, and ethylene; modified
atmosphere packaging, coatings on cardboard; direct chemical or physical treatment
on the product; and breathable packaging. Compared with breathable packaging, other
technologies have some disadvantages, such as the possibility of damage due to low
temperatures in refrigerated alternatives, high costs, consumer perception, and difficulties
in packaging operations.
[0004] Breathable packaging is one of the most commonly used packaging for perishable products
due to its benefits in terms of costs. Breathable packaging technology offers various
options, including: high permeability films; macro and microperforated films; permeable
patches and windows; air vents and valves.
[0005] Macro and micro perforated films have been disclosed in several patents (
US5130152,
US2005180664,
DE202005011737,
GB1106265,
GB1134667,
GB2141688, and
JP6199385). This alternative has some disadvantages, such as the need to seal the mouth of
the packaging, the product may block some of the perforations, and the need for additional
operations in the manufacture of the film or bag.
[0006] Permeable patches and windows have been disclosed in prior art (
US4842875,
US4943440,
US5045331,
GB1071586,
FR2686577, and
CN1036539). The main disadvantages of this technology are: the need to seal the mouth of the
packaging and the need for additional operations in the manufacture of the film or
bag.
[0008] Although some valves have been disclosed in prior art (
US3937396,
US5996800,
US2003152296,
WO2004108557,
WO2004043191,
EP0700839,
JP1279073,
JP11301743, and
JP2006125559), all valves require sealing the bag, as well as additional operations in the manufacturing
of the bag.
[0009] The packaging of the present invention discloses a combination of a flexible container
and a breathable valve, composed in turn by a ring and a breathable lid to extend
the green life of perishable products, such as fruits and vegetables. The packaging
of the present invention provides the possibility of mechanical assembly, either manually
or automatically, without the need of heat-sealing technology or additional operations
in the manufacture of the bags; it can also be opened and reopened in ripening chambers;
it is recyclable and affordable. In addition, extending the green life of the product
can increase the growth period of the fruit or vegetable in the plant.
3. SUMMARY OF THE INVENTION
[0010] The present invention provides a packaging with a breathable valve to extend the
green life of perishable products that undergo a respiratory process after being harvested,
such as vegetables and fruits. The packaging comprises a flexible container and a
valve assembly that is assembled in the mouth of the flexible package in order to
create a controlled gaseous atmosphere inside the package. In turn, the valve assembly
comprises a ring located outside the flexible container and a breathable lid located
inside the flexible container; these two components can be mechanically assembled
without the need of heat sealing technologies to close the mouth of the flexible container.
The breathable lid has fastening means to attach both parts to the middle of the flexible
container, which can be an interference fit and pressure fittings. The breathable
lid can be a plastic cover with multiple microperforations or nanoperforations, or
an annular section that allows the installation of a permeable membrane interspersed
among the ring, the flexible container and the breathable lid. The permeable membrane
can be a cavitated, microperforated, or nanoperforated film. The concentration of
oxygen, water vapor, carbon dioxide, and ethylene is controlled by the permeation
of the breathable lid, the weight and respiration rate of the packed perishable product.
The permeation of the breathable lid is controlled by the number and size of micro
and nanoperforations, in the case of the plastic cover and the micro and nanoperforated
film; and by gas permeability, in the case of the cavitated film.
4. DESCRIPTION OF THE FIGURES
[0011]
FIG. 1 illustrates a breathable valve (2) assembled and installed in the mouth of the flexible
container (1). The figure also shows an interference fit as fastening means and a
micro or nanoperforated plastic cover as breathable lid (4). In this particular embodiment,
the breathable lid (4) has a circular cavity to allow good assembly by interference
with the ring (3).
FIG. 2 illustrates a breathable valve (2) assembled and installed in the mouth of the flexible
container (1). The figure also shows an interference fit as fastening means and a
micro or nanoperforated plastic cover as breathable lid (4).
FIG. 3 illustrates a breathable valve (2) assembled, a pressure fitting (6) as fastening
means and a micro or nanoperforated plastic cover as breathable lid (4).
FIG. 4 illustrates a breathable valve (2) assembled, a pressure fitting (6) as fastening
means and a micro or nanoperforated plastic cover as breathable lid (4). The figure
also illustrates a rectangular channel (7) to facilitate release without moving parts
of the pieces to be assembled by pressure (6).
FIG. 5 illustrates a breathable valve (2) assembled, an interference fit (8) in the ring
(3) as fastening means and a micro or nanoperforated plastic cover as breathable lid
(4).
FIG. 6 illustrates another embodiment of the invention using a breathable valve (2) of square
shape, an interference fit as fastening means and a micro or nanoperforated plastic
cover as breathable lid (4).
FIG. 7 illustrates another embodiment of the invention using a breathable valve (2) of triangular
shape, an interference fit as fastening means and a micro or nanoperforated plastic
cover as breathable lid (4).
FIG. 8 illustrates another embodiment of the invention wherein the breathable lid of the
valve assembly is an annular section, allowing the installation of a permeable membrane
(10) interspersed among the ring (3), the flexible container (1) and the breathable
ring (9).
FIG. 9 illustrates the evolution of oxygen and carbon dioxide concentration over time for
two prototypes made in accordance with the present invention. It evaluates two microperforated
plastic covers with 11 and 18 microperforations that range between 250 and 300 microns
in diameter.
5. DETAILED DESCRIPTION OF THE INVENTION:
[0012] The present invention provides a packaging fitted with a breathable valve designed
to extend the green life of perishable products that undergo a respiratory process
after being harvested, such as vegetables and fruits. With reference to the embodiment
illustrated in Figures 1 and 2, the packaging comprises a flexible container (1) characterized
by the presence of at least one mouth, and at least one valve assembly (2) consisting
of two parts: a ring (3), located on the periphery and the outer surface of the flexible
container's mouth (1), and a breathable lid (4), which mechanically fits to the inner
part of the ring (3), such that the material of the flexible container's mouth (1)
is fastened between the breathable lid (4) and the ring (3).
[0013] The flexible container (1) is a flexible film, manufactured for example by casting,
blowing extrusion, flat film extrusion, coextrusion, or lamination. The polymeric
film is manufactured with a polymer preferably selected from the group comprising
polyethylene, polypropylene, polyethylene terephthalate, polyamide, polystyrene copolymers,
cellophane, polylactic acid, cellulose acetate, thermoplastic starch and its derivatives,
and mixtures thereof.
[0014] With reference to Figures 3 and 4, the valve assembly (2) comprises two parts: the
ring (3) and the breathable lid (4), which can be mechanically fitted and do not need
using heat sealing technologies to close the flexible container's mouth (1), or additional
operations in the manufacture of the bag. The breathable lid (4) has fastening means
to attach both parts to the flexible container (1) such that the film that forms the
container's mouth is fixed between the two sides of the valve. The embodiment illustrated
in Figures 3 and 4 uses a pressure fitting (6). Figures 3 and 4 also illustrate a
rectangular channel (7) in the breathable lid (4) to facilitate release without moving
parts of the pieces to be assembled by pressure (6).
[0015] With reference to Figures 1, 2 and 5, in another embodiment of the present invention,
the fastening means for attaching both parts of the valve assembly (2) to the flexible
container (1) are an interference fit on the ring (3) and a breathable lid (4). In
this sense, it is desirable for the breathable lid (4) to have tapered sidewalls to
facilitate assembly with the ring (3). With reference to Figure 5, in a particular
embodiment of the present invention, the interference fit is produced between an extension
(8) of the breathable lid (4) and the corresponding cavity in the ring (3). With reference
to Figures 5 to 7, although the preferred embodiment is a ring (3) and a breathable
plug (4) of circular shape, it is possible to use other shapes, such as triangular
or polygonal.
[0016] The ring (3) and breathable lid (4) of the valve assembly (2) may be manufactured
by injection molding or press molding, using a polymer preferably from the group comprising
thermoplastic polyurethane, vulcanized thermoplastic, thermoplastic elastomers, polyethylene,
polypropylene, polyethylene terephthalate, polyamide, polystyrene copolymers, polylactic
acid, cellulose acetate, thermoplastic starch and its derivatives, and mixtures thereof.
In a particular embodiment of the present invention, the ring (3) and breathable lid
(4) of the valve assembly (2) are made of a material whose hardness should be less
than the one that produces a mark on the fruit or vegetable. For example, the hardness
for bananas must be less than 80 Shore A for bananas, preferably less than 60 Shore
A, in order to ensure that the bananas are not damaged or dented by the valve. The
use of rounded contours is advantageous for this same reason.
[0017] With reference to Figures 1 to 7, in another embodiment, the breathable lid (4) can
be a plastic cover characterized by multiple micro or nanoperforations (5).
[0018] With reference to Figure 8, another embodiment of the present invention uses an annular
section (9) that allows the installation of a permeable membrane (10) interspersed
among the ring (3), the flexible container (1), and the annular section (9). The permeable
membrane (10) can be a cavitated, microperforated, or nanoperforated film. The cavitation
film may be manufactured using a cavitation load such as calcium carbonate. The microperforated
film may be manufactured using for example mechanical, laser, or electrostatic technology.
The present invention can use any type of breathable lid (4), even with the permeable
membrane (10) interspersed between the ring (3) and the flexible container (1). The
annular section (9) of this embodiment is mechanically fitted to the ring (3) and
the flexible container's mouth (1) for tensioning the permeable membrane (10).
[0019] The concentration of oxygen, water vapor, carbon dioxide, and ethylene can be controlled
by the permeation of the breathable lid (4), and the weight and respiration rate of
the packed perishable product. The permeation of the breathable lid (4) is controlled
by the number and size of micro and nanoperforations, in the case of the plastic cover
and the micro and nanoperforated film, and by gas permeability, in the case of the
cavitated film.
6. EXAMPLES
[0020] The following examples were obtained using a packaging prototype comprising a breathable
valve for perishable products:
Example 1:
[0021] This example evaluates a packaging prototype of the present invention having the
following characteristics: the flexible container is a bag made of a 30-microns thick
polyethylene film with dimensions of 300 by 380 mm, a valve assemblage with an internal
diameter of 32 mm with a plastic cover with 11 microperforations between 250 and 300
microns. Approximately 1.2 kg of bananas were packed and their green life at room
temperature and cooled to 13 °C was evaluated. The prototype of the disclosed packaging
was then compared to the following technologies available in the state of the art:
a 30-microns thick microperforated bag with 50 microperforations with a diameter of
200 microns, and a 30-microns thick macroperforated bag with 12 perforations with
a diameter of 12.5 mm. The packaging comprising a breathable valve increases green
life, decreases weight loss, and reduces the conversion of starch in carbohydrates
(measured as degrees Brix).
Table 1
|
Green Life |
Degrees Brix |
Weight Loss, % |
Breathable valve with 11 microperforations between 250 and 300 micros at room temperature |
More than 28 days |
12.0 |
0.49 |
Breathable valve with 11 microperforations between 250 and 300 micros at 13 °C |
More than 28 days |
6.0 |
0.17 |
Microperforated bag with 50 microperforations with a diameter of 200 microns at 13
°C |
28 days |
11.5 |
0.15 |
Macroperforated bag with 12 perforations with a diameter of 12.5 mm at 13 °C |
25 days |
14.5 |
0.60 |
Example 2:
[0022] This example evaluates a packaging prototype of the present invention with the following
characteristics: the flexible container is a bag made of a 30-microns thick polyethylene
film with dimensions of 300 by 380 mm, a valve assemblage with an internal diameter
of 32 mm with an annular section, and a mechanically microperforated film. Approximately
1.2 kg of bananas was packed and their green life cooled to 13 °C was evaluated. The
prototype of the disclosed packaging was compared to the technologies available in
the state of the art mentioned in Example 1. The packaging comprising a breathable
valve increases green life, decreases weight loss, and reduces the conversion of starch
in carbohydrates (measured as degrees Brix).
Table 2
|
Green Life |
Degrees Brix |
Weight Loss, % |
Breathable valve with a mechanical microperforated film in the annular section at
13°C |
More than 28 days |
5.0 |
0.06 |
Microperforated bag with 50 microperforations with a diameter of 200 microns at 13
°C |
28 days |
11.5 |
0.15 |
Macroperforated bag with 12 perforations with a diameter of 12.5 mm at 13 °C |
25 days |
14.5 |
0.60 |
Example 3:
[0023] This example compares the evolution of oxygen and carbon dioxide concentration at
13°C for two plastic covers with 11 and 18 perforations. The same flexible container
was used, the same valve assembly and the same number of bananas in Example 1. With
reference to Figure 9, after 4 days the concentration of gases becomes regulated to
a constant value that depends on the number of perforations.
Example 4:
[0024] An important characteristic of the breathable valve's materials is its hardness and
contours, in that no damage is caused to the perishable product while packing. This
example evaluates the effect that the hardness and contours of the material of the
packaging comprising a breathable valve has on the bananas. The effect of 3.5 kg (approximately
three bunches of green bananas) applied to the breathable valve and on the banana
peel was evaluated. Using a Shore A hardness of less than 80 and a valve with a rounded
contour is essential to prevent the banana peel from denting.
Table 3
Material |
Hardness |
Surface |
Result |
Shore A |
Shore D |
Polyurethane |
80 |
|
Rounded |
No dents |
Polyurethane |
80 |
|
Sharp edges |
Dents |
High density polyethylene |
|
55 |
Sharp edges |
Dents |
Polypropylene |
|
78 |
Rounded |
Dents |
Rubber |
62 |
|
Rounded |
No dents |
[0025] The above methods, figures, and examples are merely illustrative of the inventive
concept. Any person skilled in the art will understand that evident variations and
enhancements may be made without departing from the inventive concept, which is defined
only by the following claims.
1. A breathable packaging intended to extend the green life of perishable products is
comprised of:
a. a flexible container with a mouth; and
b. a device that allows the respiration of the perishable product, wherein the device
is fastened to the mouth of the container by a mechanical coupling.
2. The packaging of Claim 1, wherein the device that allows respiration of the perishable
product is a breathable valve.
3. The packaging of Claim 1, wherein the flexible container is a polymeric film.
4. The packaging of Claim 3, wherein the polymeric film is manufactured with a polymer
selected from the group comprising polyethylene, polypropylene, polyethylene terephthalate,
polyamide, polystyrene copolymers, cellophane, polylactic acid, cellulose acetate,
thermoplastic starch and its derivatives, and mixtures thereof.
5. The packaging of Claim 2, wherein the breathable valve is comprised of:
a. a ring located on the periphery and outer surface of the flexible container's mouth;
and
b. a breathable lid mechanically coupled to the ring.
6. The packaging of Claim 5, wherein the mechanical coupling of the breathable lid to
the ring is made using pressure fitting or interference fit.
7. The packaging of Claim 6, wherein the breathable lid has tapered annular walls.
8. The packaging of Claim 5, wherein the breathable lid has multiple microperforations
or nanoperforations.
9. The packaging of Claim 5, wherein the ring and the breathable cap are assembled in
such way that the material of the flexible container's mouth lies between the two
making part of the mechanical coupling.
10. The packaging of Claim 2, wherein the breathable valve is comprised of:
a. a ring located on the outer periphery of the flexible container's mouth;
b. an annular section mechanically coupled to the ring; and
c. a permeable membrane located between the ring and the annular section, making part
of the mechanical coupling between the two.
11. The packaging of claim 6, wherein the ring and the breathable lid are manufactured
using a polymer preferably selected from the group comprising thermoplastic polyurethane,
vulcanized thermoplastics, thermoplastic elastomers, polyethylene, polypropylene,
polyethylene terephthalate, polyamide, polystyrene copolymers, polylactic acid, cellulose
acetate, thermoplastic starch and its derivatives, and mixtures thereof.
12. A breathable valve to allow the respiration of the perishable products stored in a
flexible container,
characterized by:
a. a ring arranged to be located on the periphery and outer surface of the flexible
container's mouth; and
b. a breathable lid arranged to mechanically couple the ring and the flexible container's
mouth.
13. The valve of claim 12, wherein the ring and the breathable lid shape is circular.
14. The valve of claim 12, wherein the breathable lid has multiple microperforations.
15. The valve of claim 12, wherein the mechanical coupling is made through pressure fit
or interference fitting.
16. The valve of claim 15, wherein the breathable lid has tapered annular walls.
17. A breathable valve to allow the respiration of perishable products stored in a flexible
container,
characterized by:
a. a ring arranged to be located on the periphery and outer surface of the flexible
container's mouth;
b. an annular section mechanically coupled to the ring, arranged to receive and fast
a permeable membrane, while mechanically coupling to the ring and the flexible container's
mouth.