Note: Descriptions are shown in the official language in which they were submitted.
21S4388
EXTENDED SHELF-LIFE PACKAGE
FOR FRUITS AN~ VEGETABLES AND THE LIKE
FIELD OF THE lNv~ ON
The field of the present invention is directed to devices
for increasing the time a fruit or vegetable can be
transported, displayed and/or stored desirably, but not
necessarily, under refrigerated conditions while still being
edible.
BACKGROUND OF THE INVENTION
Fruits and vegetables continue to respire after they are
harvested. Respiration is the oxidative breakdown of sugars,
starches, and organic acids to simpler molecules including, but
not limited to, carbon dioxide and water, with an energy
release in the form of heat and metabolic energy. The ratio of
carbon dioxide produced to oxygen consumed during respiration
is normally about 0.7 to 1.3. The rate and ratio of production
of these gases during respiration can be affected by altering
certain of the characteristics of the atmosphere which
surrounds the fruit or vegetable. For example, temperature and
gaseous composition (eg. oxygen, carbon dioxide, water, and
lS ethylene concentrations) are known to affect these rates and
ratios.
It is known that most produce (fruits and vegetables) are
typically tolerant of carbon dioxide levels up to about 5-10
percent, and tolerant of oxygen levels of as little as about
1-5 percent. However, once these limits are passed, fruits and
vegetables can incur physiological damage, with increases in
anaerobic respiration and the development of off flavors due to
accumulation of such chemical compounds as ethanol and
acetaldehyde. The tolerance of fruit and vegetables to carbon
dioxide, oxygen, and other gases (eg. ethylene) is known to be
21~43~8
dependent upon the temperature at which the fruit or vegetable
has been and is being maintained, the physiological condition
of the fruit or vegetable, the maturity of the fruit or
vegetable, and the manner, physically, in which the fruit or
vegetable has been previously treated.
Past packaging systems have attempted to optimize the
atmospheric composition surrounding the food in an attempt to
minimize respiration and maximize shelf life. For example, an
ideal film used to package fruits or vegetables would allow
more carbon dioxide to exit than oxygen to enter, since there
is about a one-to-one correspondence between moles of oxygen
consumed to moles of carbon dioxide produced, coupled with the
intolerance of most fruits and vegetables to carbon dioxide
levels greater than about 5-10 percent as discussed above.
Typically, the carbon dioxide permeability of such an ideal
film should be somewhere in the range of 3 to 5 times greater
than the oxygen permeability. Low-density polyethylene and
polyvinyl chloride films, commonly used in food packaging,
possess this property.
Those skilled in the art have also utilized oxygen, carbon
dioxide, and ethylene sorbents in food packaging systems as an
attempt to modify the atmosphere ~uL~ounding the fruit or
vegetable. But, as is well known, these materials do not
address the problems associated with incorrect humidity
control. That is, desiccation, condensation or wilting.
It is known that one of the major atmospheric variables
affecting shelf-life is relative humidity. If the relative
humidity is too low, transpirational damage occurs. This
results in a loss of turgidity, eg. wilting, which leads to
desiccation, increased respiration, and, ultimately, an
unmarketable and inedible product. If the relative humidity is
high, moisture can condense on the produce (fruit and
vegetables). This yields conditions favorable for microbial
growth due to the presence of free water which encourages the
growth of bacteria and fungi, resulting in spoilage of the
fruit or vegetable. Condensation on the film package surface
may also effect the packaging gas permeability, leading to
-- 3
21~4388
production of an unfavorable surrounding atmosphere, as well as
unsightly water droplets which act as loci for bacterial/fungal
proliferation.
With some existing film fruit and vegetable packages, which
can maintain an adequate relative humidity inside the packaging
system, moisture condensation is a significant problem. Those
skilled in the art have attempted to overcome this problem by
inclusion of desiccant moisture absorbents in the packaging
system in an attempt to lower the relative humidity.
Unfortunately, these systems frequently lower the relative
humidity excessively, leading to wilting. Anti-fog films are
available that prevent visible condensation on the film, but
condensation on the product can still occur. Because this
leads to an environment conducive to the growth of bacteria and
lS fungi, anti-fog films are not totally satisfactory.
Those of skill in the meat packaging industry have
inco~o~ated absorbent trays inside packaging materials.
However, these absorbents have only been designed to pick up
moisture at or near the lower region of the meat by direct
physical contact. Such a system would do nothing to remove
water from other areas of the packaged product. That is, near
the top of the fruit or vegetable. Accordingly, they would not
be satisfactory.
Nishino et al. in U.S. Patent No. 4,061,785 disclose a
product which incorporates an anti-fungal or anti-bacterial
pesticide within the packaging material to inhibit rotting.
Although this system may be scientifically effective in some
cases, the public concern about the use of pesticides in such
proximity with edible foods makes this option unacceptable. In
fact, the long-term effects of such a product are essentially
unknown.
U.S. Patent No. 4,961,632, discloses the use of an
absorbent material laminated to a film to maintain a dry
environment inside a bag utilized for the storage of electronic
equipment and dry food-stuffs. Unfortunately, this product
does not address the problem of storing fruits and vegetables
and the need to maintain a high humidity inside the bag while
21~388
eliminating the occurrence of condensation drops on the
contents of the bag. While unnecessary in the electronic5
area, also not addressed is the need (by the produce consumer)
for the consumer to see inside the bag for quick identification
of the viability of its contents.
In summary, none of the above mentioned methods or products
have adequately addressed the combination of needs required by
an acceptable produce storage container. That is, the need to
maintain high humidity conditions in the range of from about
80 percent to less than about 100 percent relative humidity (to
prevent wilting) while, at the same time, eliminating the
presence of condensation beads or drops of water on the fruit
or vegetable so as not to promote microbial decay.
ASPECTS OF THE INVENTION
Accordingly, it is a general aspect of the present
invention to provide a produce storage container capable of
preserving fruits, vegetables and the like that is
environmentally benign (pesticide-free), inexpensive,
convenient, simple to use, and which provides a significantly
longer shelf-life to fruits, vegetables and the like which are
stored in such a system.
It is ~other aspect of the present invention to provide a
method for producing such a produce storage container.
These ~d other aspects and the broad scope of
applicability of the present invention will become apparent to
those of skill in the art from the details given hereinafter.
However, it should be understood that the detailed description
of the presently preferred embodiments of the present invention
is given only by way of illustration because various changes
and modifications well within the spirit and scope of the
invention will become apparent to those of skill in the art in
view of this detailed description.
2154388
SUMMARY OF THE INVENTION
In response to the foregoing problems and difficulties
encountered by those in the art, a new and improved produce
storage container is provided which significantly increases
the amount of time that produce or the like can be typically
stored under refrigerated conditions before spoilage occurs.
Of course, the produce storage container may be used to store
other items which would benefit from storage in the controlled
relative humidity environment disclosed below. In this regard
the term "produce" is used herein to generally designate any
such item. Generally speaking, the container is made up of at
least two elements or parts.
The first element or part of the container is, e.g., a bag.
The bag may, for example, be formed from a thermoplastic
material. Alternatively, the bag may be formed from cellose
acetate. The thermoplastic material, in some embodiments, may
be one or more polyolefins or another thermoplastic material
such as polyvinyl chloride. The thermoplastic polyolefin may
be selected from the group including one or more polyethylenes,
polypropylenes and polybutylenes. In some embodiments, the
polyethylene is a linear low density polyethylene. The
interior of the bag forms a relative humidity maintaining
compartment. The bag is also provided with a mouth which is
adapted to be selectively opened and retainingly closed so that
produce can be placed in or removed from the relative humidity
maintaining compartment. As is well known to those of skill in
the art, the mouth of the bag can be provided with any
conventional mechAni~m for maintaining it in a closed
configuration. Examples of such configurations include, for
example, Dow Chemical Co. ZIPLOC~ brand closing mech~n;sms,
VELCRO0 brand closing mechanisms, a strip of adhesive, or a
deformable wire which can be wrapped around the mouth of the
bag when it is in a gathered and closed configuration.
Alternative configurations or designs well known to those of
skill in the art are, of course, possible.
21S4388
In order to increase the time that produce can be stored,
the bag is formed from a material which substantially prohibits
the passage of gaseous oxygen into the compartment when the
mouth is closed. As used herein the term "substantially
prohibits the passage of gaseous oxygen" refers to a material
which has an oxygen permeability in the range of from about
0.05 to about 500 tcubic centimeters (at stAn~Ard temperature
and pressure) X millimeters per square centimeter per second
per centimeter of mercury] X 101. Such a material typically
also generally prohibits the passage of microbes into the
compartment. In some embodiments the bag may be formed from a
material which is transparent so that the condition of the
contents can be visually ascertained without opening the
container.
The second element or part of the container is a moisture
controlling device which is located within the compartment.
When produce is placed in the relative humidity maintaining
compartment and the mouth of the bag is closed, the relative
humidity within the compartment will rise to high levels as the
produce transpires or gives off moisture. The moisture
controlling device serves to wick condensed and/or pooled
liquid away form the produce while still allowing the relative
humidity within the compartment to remain in the range of from
at least about 80 percent to less than 100 percent. This
action retards, if not eliminates, an environment which is
conducive to the growth of bacteria or other harmful organisms
because they tend to flourish in such pooled and/or condensed
water ("free water").
In some emhoAiments the bag is formed from a material which
is more permeable to gaseous carbon dioxide than to gaseous
oxygen. In particular, the material would generally allow
passage of gaseous carbon dioxide out of the compartment when
the mouth of the bag is closed.
In some embodiments the moisture controlling device may be
formed, in whole or part, from cellulose. The cellulose so
utilized may be one or more of several different types. For
example, the cellulose may be in the form of cellulose sheet,
21543~8
tissue, paper towel, paper, bacterially produced cellulose,
wood pulp, wood fluff pulp, cotton, cotton liners, rayon
(reconstituted cellulose).
In other embodiments the moisture controlling device may be
formed from a matrix of a thermoplastic web and hydrophilic
cellulosic particles. As used herein the term "particles" is
intended to include fibers and groups of fibers. The web may
be formed from one or more materials including woven webs and
nonwoven webs such as meltblown webs, spunbonded webs and
apertured films. The matrix may include a meltblown web and
hydrophilic cellulosic particles, a spunbonded web and
hydrophilic cellulosic particles or a bonded carded web. Where
the matrix is a spunbonded web and hydrophilic cellulosic
particles, the matrix may be hydroentangled to produce a
spunlaced matrix.
The hydLu~hilic cellulosic particles utilized in the matrix
may be selected from one or more of the group including
cellulose sheet particles, tissue particles, paper towel
particles, paper particles, bacterially produced cellulose
particles, wood pulp particles, wood fluff pulp particles,
cotton, cotton linters, rayon particles (reconstituted
cellulose). As was stated earlier the term "particles" is
intended to include all forms of cellulosic material and, in
particular, fibrous forms and non-fibrous forms such as
particulate cellulosic materials available under the trade
designation AVICEL~.
As was previously stated, the moisture controllin-g device
is capable, in the presence of produce or the like (fruits,
vegetables etc.), of wicking pooled and/or condensed water away
from the contents of the compartment while allowing the
humidity within the compartment, when the mouth is closed, to
be maintained within the range of from at least about 80
percent to less than 100 percent. More particularly, within
the range of from at least about 80 percent to less than about
95 percent. Even more particularly, within the range of from
at least about 85 percent to less than about 95 percent. Yet
21 54~8~
even more particularly, within the range of from at least about
85 percent to less than about 90 percent.
The amount of hydrophilic cellulosic material necessary to
wick the pooled and/or condensed water away from the contents
of the compartment while still achieving the desired relative
humidity ranges within the compartment will vary with the size
of the container, the type of fruit and/or vegetable(s) the
container is designed to store and the quality (freshness or
physical condition) of the fruit and/or vegetables(s) actually
stored. Additionally, this will also vary der~n~ing upon the
type of hyd~o~hilic cellulosic material utilized. Another
factor is that, since the cellulosic material is conformable,
it may also be employed directly to blot any free moisture
present on the produce arising from a wA~hi~g step prior to
storage. However, generally speaking, at least about one (1)
gram of hydrophilic cellulosic material should be present in
the moisture controlling device per 300 grams of produce to be
contained in the container. More particularly, at least about
two (2) grams of hydrophilic cellulosic material should be
present in the moisture controlling device per 300 grams of
produce to be contained in the container. Even more
particularly, at least about four (4) grams should be present
in the moisture controlling device per 300 grams of produce to
be contained in the container.
In other embodiments the moisture controlling device may be
formed from first and second juxtaposed and joined layers with
the first layer being the matrix of a thermoplastic web and
hydrophilic cellulosic particles and the second layer being a
spllnhon~ web. In this embodiment the second layer, the
spunbonded web, acts as an isolating agent so that the matrix
which wicks and retains wicked water, retains the wicked water
substantially out of physical contact with the fruit or
vegetable(s). This lessens the likelihood of bacteria or other
harmful organisms coming in contact with the fruit or
vegetable(s) as a result of their growth in pooled water on the
surface of the fruit or vegetable(s). Further, it also lessens
2154388
the likelihood of the rapid growth of bacteria in such pooled
water sites on the produce.
In some embodiments the bag may be formed from a
transp~rent material so as to allow visual inspection of the
contents of the container.
In some embodiments, the moisture controlling device may
define one or more apertures adapted to provide an enhanced
view of produce contained within the container to a consumer
who wishes to inspect the contents of the container without
opening the container. Alternatively, indicator devices may be
incorporated into the device to visually or otherwise indicate
the status of the items contained within the container.
Other and further advantages and aspects of the present invention will become
more a~p~uent to those skilled in the art in view of the following detailed description of
the preferred embodiments and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
20 In the accompanying drawings:
Fig. 1 is a front perspective view of one embodiment of a produce storage container made
in accordance with the teachings of the present invention;
Fig. 2 is a longitudinal cross section of an embodiment of the moisture controlling device
25 illustrating a one-layered structure;
Fig. 3 is a longitudinal cross section of another embodiment of the moisture controlling
device illustrating a illustrating a multi-layered structure;
Fig. 4 is an exploded view of a matrix of a thermoplastic web and hydrophilic cellulosic
particles.
Fig. 5 is a front perspective view of another embodiment of a produce storage container
where the moisture controlling device defines one or more apertures.
Fig. 6 is a schematic illustration of a method for forming the produce storage container
of the present invention.
3 5 Fig. 7 illustrates yet another embodiment of the present invention.
-- 10 --
2154388
DETATnF~n DESCRIPTION
Turning now to the Figures where like reference numerals
represent like structure and, in particular, to FIG. 1 which is
a front perspective view of one embodiment of a produce storage
container 10 made in accordance with the teachings of the
present invention. The produce storage container 10 desirably
has a relative humidity maintaining compartment lZ which is
configured to receive produce or, for that matter, any article
which would benefit from storage in a controlled humidity
environment. Generally speaking, the container 10 is made up
of at least two components.
The first component of the container 10 is a bag 1~. The
bag 1~ may, for example, be formed from any solvent cast, air
blown, or cast film which may be amorphous or semi-
crystalline. This includes, without limitation, polyethylenes,
polypropylenes, polyvinyl chloride, polyvinylidene chloride,
cellulose acetate, polystyrene, nylon-6, polyester,
polycarbonate, ethylcellulose, methylcellulose, polyvinyl
alcohol, polyvinyl fluoride, cellulose triacetate,
polychlorotrifluoroethylene and vinylchloride acetate. Many
of these materials are thermoplastic and, as a group,
thermoplastic materials are generally acceptable for use in the
present invention. The thermoplastic material, in some
- 10a -
215~388
embodiments, may be one or more polyolefins, blends of
polyolefins, and blends including olefin comonomeric polymers.
In particular, the thermoplastic polyolefin may be one or more
polyethylenes, polypropylenes and/or polybutylenes and blends
of any of these. If the bag 1~ is formed from a thermoplastic
polyethylene material, the polyethylene may be a linear low
density polyethylene.
It is the interior of the baq 1~ that forms the relative
humidity maintaining compartment 12. The bag 1~ is also
provided with a mouth lC which is configured to be selectively
opened and retainingly closed so that produce (not shown) can
be placed in or removed from the compartment 12. The mouth 16
can be provided with any conventional me~h~n;~m 18 for
maintaining it in a closed configuration when such is desired
while still being able to access the compartment 12 through the
mouth 16. Such configurations are well known to those of skill
in the art and include, for example, Dow Chemical Co. ZIPLOC~
brand closing mechAn;cms~ VELCRO0 brand closing mechAnisms, an
adhesive flap or a deformable wire which can be wrapped around
the mouth 16 of the bag 1~ when it is in a gathered and closed
configuration. In order to increase the time that produce can
be stored, the bag 1~ is desirably formed from a material which
substantially prohibits the passage of gaseous oxygen and
microbes into the compartment when the mouth is closed. In
some embodiments, the bag 1~ may be formed from a material
which is transparent so that the condition of the contents of
the compartment 12 can be ascertained by an individual without
the necessity of opening the container lO. Those of skill in
the art will readily recognize that bags 1~ of this type are
readily available from a wide variety of sources. For example,
such bags can be obtained from most grocery stores under the
trade designation, for example, Dow Chemical Co. ZIPLOC~ brand
storage bags.
In some embodiments the bag 1~ may be formed from a
material which is more permeable to gaseous carbon dioxide than
to gaseous oxygen. In particular, the material would generally
-- 11 --
21!~438~
allow passage of gaseous carbon dioxide out o~ the compartment
12 when the mouth 16 of the bag 1~ is closed.
The second component of the container 10 is a moisture
controlling device 20 which is located within the compartment
12. When produce is placed in the compartment 12 and the mouth
16 of the bag is closed, the device 20 allows the humidity
within the compartment 12 to be maintained at a high level.
That is, the device allows the relative humidity to be
maintained within the closed compartment 12 in the range of
from at least about 80 percent to less than 100 percent for an
extended period of time. The device 20 also is capable of
wicking condensed water vapor (liquid water) off of and away
from the surface of any produce with which the device 20 comes
into contact. In this regard the device 20 acts to retard, if
not eliminate, an environment conducive to the growth of
bacteria or other harmful organisms.
In some embodiments, the moisture controlling device 20 may
be formed from a one layered structure 2Z as is illustrated in
cross-section in FIG. 2. Alternatively, the device 20 may be
multi-layered 22, 2~ as is illustrated in cross-section in FIG.
3. In either case, at least one of the layers 22 may desirably
be formed, in whole or part, from cellulose. The cellulose so
utilized may be one or more of several different types. For
example, the cellulose may be in the form of cellulose sheet,
tissue, paper towel, paper, bacterially produced cellulose,
wood pulp, wood fluff pulp, cotton, cotton liners, rayon
(reconstituted cellulose). Those of skill in the art will
readily r~cosni7e that cellulosic sheets etc. of these types
are readily available from a wide variety of sources. For
example, such sheets can be obtained from the Kimberly-Clark
Corporation under the trade designation HI-DRI~ paper towels.
In some embodiments, the layer 22 of the moisture
controlling device 20 which is desirably formed, in whole or
part, from cellulose, may be formed from a matrix 26 of a
thermoplastic web 28 and hydrophilic ceIlulosic particles 30.
Such a matrix 26 is illustrated in Fig. 4. The web 28 may be formed from one or more
materials including
21~43~
meltblown webs, spunbonded webs and apertured films. The
matrix 26 may include a meltblown web and hydrophilic
cellulosic particles, a spunbonded web and hydrophilic
cellulosic particles or a bonded carded web. Where the
components 28, 30 of the matrix 26 are a spunbonded web and
hydrophilic cellulosic particles, the matrix 26 may be
hydroentangled to produce a spunlaced matrix. Those of skill
in the art will readily recognize that these materials are
readily available from a wide variety of sources. For example,
such meltblown, spunbonded and coformed materials can be
obtained from the Kimberly-Clark Corporation.
The hydrophilic cellulosic particles 30 utilized in the
matrix may be selected from one or more of the group including
cellulose sheet particles, tissue particles, paper towel
particles, paper particles, bacterially produced cellulose
particles, wood pulp particles, wood fluff pulp particles,
cotton, cotton linters, rayon particles (reconstituted
cellulose).
As was previously stated, the moisture controlling device
20 is capable, in the presence of produce (fruits, vegetables
etc.), of allowing the relative humidity to be maintained
within the compartment 12 when the mouth 16 is closed at a high
level while still being capable of wicking pooled and/or
condensed liquid water off of and away from the surface of the
2S contents of the container 10. For example, the device 20 is
capable of allowing the relative humidity to be maintained
within the range of from at least about 80 percent to less than
100 percent. More particularly, within the range of from at
least about 80 percent to less than about 95 percent. Even
more particularly, within the range of from at least about 85
percent to less than about 95 percent. Yet even more
particularly, within the range of from at least about 85
percent to less than about 90 percent.
It has been found that the device 20 is capable of allowing
the relative humidity within the compartment 12 to remain
within these desired ranges because of the attributes of
cellulose fibers in that they: (1) rapidly wick and absorb
- 13 -
21 5~3~8
stAn~ing water which contacts them but; (2) only weakly absorb
surrounding water vapor. This later point, stated another way,
means that cellulosic materials generally have a much higher
relative humidity equilibrium point, for a given moisture
loading, than other types of absorbents. That is, cellulosic
materials will more readily transpire wicked water in the form
of water vapor than, for example, superabsorbent materials and,
in particular, inorganic desiccants which do not readily
release moisture in the form of water vapor. This higher
relative humidity equilibrium point allows the container 10 of
the present invention to maintain high relative humidity for an
extended time when the mouth 16 of the bag 14 is closed. In
contrast, if a superabsorbent material was utilized as the
particulate material 30 for the moisture controlling device 20,
the superabsorbent material would readily wick and absorb the
stA~;ng liquid water with which it came in contact. However,
the superabsorbent material also more strongly holds water
vapor and, accordingly, would act as a desiccant within the
closed confines of the compartment 12. This action would
greatly hasten the wilting of produce or the like contained
within the compartment 12. Put yet another way, it can be
stated that, in col.L~ast to superabsorbent materials and
inorganic desiccants, the present invention, because of the
higher relative humidity equilibrium point of cellulosic
materials, creates a system which is interactive with the
moisture humidity in the environment of the closed compartment
12 in that, when the compartment 12 is opened and thereafter
closed, the moisture controlling device 20 readily responds to
the concomitant lowering of the relative humidity within the
compartment 12 by interactively giving off water vapor to re-
establish the desired high relative humidity range of at least
about 80% to 100%.
Those of skill in the art will, upon reflection on the
present specification, readily recognize that the amount of
hydrophilic cellulosic material necessary to allow maintenance
of the desired relative humidity ranges and also properly wick
moisture away from the produce will vary with the size of the
- 14 -
2i5~3~8
compartment 12 and the type of fruit and/or vegetable(s) the
container 10 is designed to store. Additionally, the amount of
hydrophilic cellulosic material necessary to rapidly wick
moisture while achieving the desired relative humidity ranges
will also vary depending upon the type of hydrophilic
cellulosic material utilized. However, generally speaking, at
least about one (1) gram of hydrophilic cellulosic material
should be present in the moisture controlling device 20 per 300
grams of produce to be contained in the container 10. More
particularly, at least about two (2) grams of hydrophilic
cellulosic material should be present in the moisture
controlling device 20 per 300 grams of produce to be contained
in the container 10. Even more particularly, at least about
four (4) grams should be present in the moisture controlling
device 20 per 300 grams of produce to be contained in the
container 10.
An additional factor affecting the function of the present
invention, at least as regards to the capability of the device
20 to readily wick pooled water off of produce contained within
the compartment 12, is the degree of contact between the
exterior surface of the contents of the container 10 and the
surface of the device 20. Naturally, the greater the degree of
surface-to-surface contact between these two surfaces, the
greater the likelihood that the device 20 will be able to
rapidly wick pooled water from off of the surface of the stored
contents. Accordingly, it is generally desired that the
moisture controlling device 20 be sized to cover at least about
20% of the surface of the compartment 12. For example, the
moisture controlling device 20 may be sized to cover at least
about 30% of the surface of the compartment 12. More
particularly, the moisture controlling device 20 may be sized
to cover at least about 40% of the surface of the compartment
12. Even more particularly, the moisture controlling device 20
may be sized to cover at least about 50% of the surface of the
compartment 12. That is, at least about 75% of the surface of
the compartment 12 may be covered by the device 20. In some
embodiment, at least as much as 90% of the surface of the
- 15 -
21S43~
compartment 12 may be covered by the moisture controlling
device 20.
As earlier stated, in some embodiments, (See FIG. 3.) the
moisture controlling device 20 may be formed from first 22 and
second 2~ juxtaposed and joined layers with the first layer 22
being the matrix 26 of a thermoplastic web 28 and hydrophilic
cellulosic particles 30 and the second layer 2~ being a
spunbonded web. In this embodiment the second layer 2~, the
spllnhonA~ web, acts as an isolating agent so that the matrix
26 which retains wicked water, retains the wicked water
substantially out of physical contact with the fruit or
vegetable(s). This l~ccen-c the likelihood of large
concentrations of bacteria or other harmful micro-organisms
coming in contact with the fruit or vegetable(s) because it
l~ss~nc the chance that the contents of the container 10 will
be subjected to eyce-csive wetness. It is well known that
excessive wetness can promote microbial growth and thus decay.
It is envisioned that the present invention may be utilized
in quite large emho~iments which may, for example, line the
interior of a transportation system such as a truck or rail
car. In such situation, the bag 1~ would not have to be
transparent. Additionally, in such large applications, it may
be neceC-c~ry~ in order to achieve optimum results, for the
device 20 to be made up of more than one sheet with the
contents of the bag 1~ and the sheets of the device 20 being
alternated so that pooled/condensed water located in the
interior of the large bag can be rapidly wicked into the device
20. Naturally, in such a large application, the device 20
could, as stated above, be separate sheets or, alternatively,
one large sheet that is, in serpentine fashion, folded back and
forth to effect sandwiching of the contents.
In some emho~iments~ where consumer inspection of the
produce is desired, the bag 1~ may be formed from a transparent
material so as to allow visual inspection of the contents of
the container 12. Alternatively, as will be discussed more
thoroughly below, the device 20 can be configured to allow
greater ease of viewing the contents.
- 16 -
21S4388
FIG. 5 illustrates yet another embodiment of the present
invention where the moisture controlling device 20 is
configured to define one or more apertures 32 adapted to
provide an enhanced view of produce contained within the
container 10.
The container 10 may be sold in a prefabricated form as an
integral unit or the bag 1~ and the device 20 may be sold
separately. For example, the device 20 could be sold in a
rolled sheet form which could be regularly perforated so that
various sizes of sheet could be removed from the roll. Thus,
a consumer would form the device 20 by tearing off a portion
from a roll of such sheet material. Thereafter, the consumer
would wrap the produce in the device 20 to the extent necessary
and insert the wrapped produce into a bag 1~ and close the
mouth 16 of the bag 14 for subsequent storage of the produce.
FIG. 6 is a schematic illustration of a method for forming
the container 10 of the present invention. Supply roll 34a,
34b supply the material from which the bag 14 is manufactured.
Supply rolls 36a, 36b supply the material from which the device
20 is formed. Layers from each of the rolls are juxtaposed
with the layers 36a, 36b being sandwiched between the layers
34~, 3~b by a pair of nip rollers 38. Thereafter, a
conventional sealing/perforating bar ~0 forms the seal which
creates the bottom of each bag 1~ and also perforates the
layers in the cross-machine direction so that individual bags
1~ can be separated as desired. Also, conventional side
sealing devices ~2 seal the for layers together along their
machine direction periphery to unify the side edges of the bags
14. Lastly, the still unified roll of bags 1~ is wound up on
storage roll 44.
FIG. 7 illustrates yet another embodiment of the present
invention. In this embodiment of the container 10 , the
moisture controlling device 20 is, itself, in the form of a bag
~6. The mouth ~8 of the bag 46 may desirably be provided with
a closing mech~n;cm equivalent to the mech~n;cm 18 of the bag
14. Alternatively, the mouth ~8 of the bag ~6 may be provided
with a conventional elastic periphery 50 so that the mouth ~8
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of the bag 46 can be stretched open to receive produce but will
then retract back into snug contact with the contents (not
shown) of the bag ~6. As is pictured in FIG. 7, in this
embodiment it is desirable for the bag 46 to define view ports
32 so that the condition of the contents of the bag ~6 can
readily be viewed without the need for opening it. Once an
item to be stored is placed within the bag ~6, the bag 46 is
then placed within the bag 14 and the mouth 16 of the bag 14 is
closed using the mech~nism 18.
The invention will now be discussed with regard to specific
examples which will aid those of skill in the art in a full and
complete understanding thereof.
EXAMPLE 1
An experiment was conducted on a group of romaine lettuce
heads of substantially the same form and appearance. Each head
of lettuce weighed approximately 7 ounces. Because the heads
of lettuce were obtained from the same batch at the same
source, it is assumed that they all were (1) harvested at about
the same time; and (2) subjected to substantially the same
treatment.
Seven of the heads of lettuce were selected to evaluate
seven different packaging systems.
The first head of lettuce was placed in a 10.5 inch by 12
inch polyethylene bag having a ZIPLOC~ brand closure. The bag
was then sealed using the provided integral ZIPLOC~ brand
closure.
The second head of lettuce was placed in a polyethylene bag
identical to the bag into which the first head of lettuce was
placed. Also placed inside of the bag was a two layer
composite sheet. The sheet was approximately eight inches by
sixteen inches in size. The first layer of the sheet was
coformed and the second layer was spunbonded polypropylene
treated for wettability with Triton X1022 brand surfactant, a
food-grade surfactant, which can be obtained from the Rohm and
Haas Chemical Company of Philadelphia, Pennsylvania. Triton
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Xl020 brand surfactant is known by those of skill in the art to
be an octylphenoxypolyethoxyethanol. The treatment with Triton
X102~ brand surfactant consisted of applying about 0.016 weight
percent of the Triton Xl022 brand surfactant to the first layer
of the sheet, and about 0.08, weight percent, to the second
layer of the sheet. The coformed layer was approximately 70%,
by weight, processed wood pulp and 30%, by weight, meltblown
polypropylene. The basis weight of the sheet was about 225
grams per square meter (gsm). The basis weight of the coformed
layer was about 190 gsm. The basis weight of the spunbonded
layer was about 35 gsm. In this experiment, the sheet was
sized so that it would cover about 58% of the surface of the
interior of the bag. That is, about S8% of the surface of the
compartment.
The third head of lettuce was placed in a polyethylene bag
identical to the bag used for the first head of lettuce. Also
placed in the bag was a 2-ply pulp tissue sheet which was 11
inches by 9 inches in size. The pulp tissue sheet weighed
about 8.5 grams. The pulp tissue sheet was wrapped around
the head of lettuce in a manner substantially identical to the
sheet wrapped around the second head of lettuce. That is, so
that it would cover about 58% of the surface of the interior of
the bag. That is, about 58% of the surface of the compartment.
The fourth head of lettuce was placed in a polyethylene bag
identical to the bags used for the first three heads of
lettuce. Before the fourth head of lettuce was placed inside
its bag, it was placed inside of a HUGGIES2 brand UltraTrim for
Him Step 4 superabsorbing diaper contAining polyacrylate
superabsorbing polymer. In like manner to the second and third
heads of lettuce, the diaper was wrapped around the fourth head
of lettuce so that it would cover about 58% of the surface of
the interior of the bag. That is, about 58% of the surface of
the compartment.
The fifth head of lettuce was placed in a polyethylene bag
identical to the bags used for the first four heads of lettuce
with the exception that the bag was perforated about every
centimeter with holes having an approximate diameter of from
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about 0.5 to about 1 millimeters. The function of the holes
was to allow passage of gases and vapor into and out of the
bag.
The sixth head of lettuce was placed in a polyethylene bag
identical to the apertured bag into which the fifth head of
lettuce was placed. Also placed inside of the bag was a two
layer composite sheet substantially identical to the sheet
utilized for the second head of lettuce. The two layer
composite sheet was wrapped about the sixth head of lettuce in
a manner substantially identical to the wraps of the second,
third and fourth heads. That is, so that it would cover about
58% of the surface of the interior of the bag. That is, about
58% of the surface of the compartment.
The seventh head of lettuce was placed on top of a piece of
the two layer composite sheet which was used to wrap the second
and sixth heads of lettuce. The two layer composite sheet was
approximately eight inches by eight inches in size. Thus, the
seventh head of lettuce was essentially unprotected and
unwrapped.
All seven heads of romaine lettuce were stored at
approximately 50% relative humidity (RH) and 40 degrees
Centigrade (C.).
After only a few days, the seventh, unprotected, head of
lettuce had wilted.
After one week, both the fifth head of lettuce, which had
been stored in the perforated bag, and the sixth head of
lettuce, which had been stored in the perforated bag along with
a two layer composite sheet, showed obvious signs of wilting
and rotting.
8etween the first and second week, the first head of
lettuce, which had been stored in the polyethylene bag,
demonstrated signs of rotting. Also, between the first and
second week of storage, the fourth head of lettuce, which had
been stored in the polyethylene bag and wrapped with a
superabsorbent diaper, demonstrated signs of wilting.
At the end of this experiment, after 6 weeks: (1) the first
head of lettuce was significantly and thoroughly rotted; (2)
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the fourth head of lettuce was moderately wilted; and (3) the
fifth, sixth and seventh heads of lettuce were all severely
wilted and rotted.
By comparison, at the conclusion of this experiment, after
6 weeks, the second and third heads of lettuce were both still
fresh, crisp, and edible, and showed no signs of wilting or
rotting.
EXAMPLE 2
A similar experiment was run as above with mung
bean sprouts divided into batches which were equal in form
and weighed approximately 5 ounces each. Because the mung bean
sprouts were obtained from the same batch at the same source,
it is assumed that they all (1) represented an equivalent stage
of growth; and (2) were subjected to substantially the same
treatment.
A batch of mung bean sprouts was placed into each of the
six packaging systems and wrapped as described in Example 1.
A seventh batch of mung bean ~louLs was left unprotected on a
two layer composite sheet as described with regard to the
seventh head of lettuce in Example 1.
At the end of one week, (1) the first batch of mung sprouts
was affected by rot and wilting to a moderate extent; (2) the
fourth batch of mung sprouts was slightly effected by rot;(3)
the fifth and sixth batches of mung sprouts were thoroughly
rotted and very dark brown in color; and (4) the seventh batch
of mung ~ou~s was unacceptably desiccated.
By comparison, the second and third batches of mung sprouts
were both fresh and crisp with no visual evidence of rot.
EXAMPLE 3
A similar experiment was run as in Example 2 with
strawberries divided into batches which were equal in form
and weighed approximately 4 ounces each. Because the
strawberries were obtained from the same batch at the same
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source, it is assumed that they all were (1) harvested at about
the same time; and (2) subjected to substantially the same
treatment.
A batch of the strawberries was placed into each of the
six packaging systems and wrapped as described in Example 1.
A seventh batch of the strawberries was left unprotected on a
two layer composite sheet as described with regard to the
seventh head of lettuce in Example 1.
At the end of one week, (1) over half of the strawberries
in the first batch were wet, mushy and inedible; (2) the
strawberries in the fourth batch were almost completely firm
and fresh; (3) the strawberries in both the fifth and sixth
batches were thoroughly mushy; and (4) the strawberries in the
seventh batch were dripping wet, mushy, and thoroughly
softened, with white mold.
By comparison, over 75%, by volume, of the second and third
batches of strawberries were still fresh and firm with the
remainder showing some signs of softening.
EXAMPLE 4
The procedures of Example 3 were repeated with the exception
that the strawberries were observed for three weeks.
After three weeks, (1) the strawberries in batches one, two
and three were still firm but showed signs of mold in about ten
percent of the strawberries; (2) the strawberries in the fourth
batch were more damaged with about fifty percent of them
rotting; (3) the strawberries in the fifth and sixth batches
were completely covered with a layer of green-grey mold with no
signs of the red strawberry showing through; and the
strawberries in the seventh batch were severely dried out with
about twenty percent of the surface covered with a white mold.
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3 S 8
It is to be understood that variations and modifications of
the present invention may be made without departing from the
scope of the invention. It is also to be understood that the
scope of the present invention is not to be interpreted as
limited to the specific embodiments disclosed herein, but only
in accordance with the appended claims when read in light of
the foregoing disclosure.
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