Note: Descriptions are shown in the official language in which they were submitted.
CA 02319887 2000-09-19
SHRINK PACKAGING OF FOOD PRODUCTS
FIELD OF THE INVENTION
The invention relates generally to a package for a food product which
is part of a meal kit that includes multiple food items. More specifically,
the
invention relates to a package that limits migration of moisture from the food
product during storage and display of the meal kit. The invention also relates
to a
method of packaging the food product and a packaging system for the food
product
contained in a meal kit.
BACKGROUND OF THE INVENTION
Pre-packaged meal kits which include multiple food items that
require a minimal amount of consumer preparation and allow for quick assembly
have become increasingly popular. Generally, a meal kit contains various ready-
to-
eat food items, and optionally a beverage, to provide an essentially complete
meal.
Typical food items include meat products, cheese, and farinaceous food
products,
e.g., pancakes, waffles or buns. These food items may be contained in a main
tray
having one or more compartments.
Because of the perishable nature of certain food items, the meal kits
should be stored and displayed at refrigerated temperatures. In stores, the
meal kits
typically may be displayed in open-front refrigerated cases. The temperature
in these
display cases may fluctuate with the cycling of the refrigeration system.
Additionally, a temperature gradient may exist through the depth of the case
as a
result of the front of the case being open to ambient conditions in the store.
The texture of the farinaceous food products may be affected by
temperature fluctuations. More particularly, migration of moisture may result
in
portions of the product or the entire product becoming -drier, tougher or
otherwise
less fresh and appealing. Although the main tray of the meal kit may be
hermetically
sealed and the compartments gas flushed, moisture still may be lost from the
farinaceous food product and at a rate more rapid than is desirable.
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It is known to separately package the farinaceous food product prior
to its being deposited in the main tray to further limit moisture loss. The
packaging
material may be a thinly formed flexible material to which heat may be applied
to
shrink the material to fit more closely about the farinaceous food product,
i.e.
"shrink wrap". Because the package is sealed prior to shrinking, the type of
seal is
chosen to ensure that the integrity of the seal is maintained during
subsequent
shrinking. For this reason, such a package typically is sealed using a hot
wire heat
seal at both ends and includes an electrostatic lap seal extending
longitudinally of the
product between the end seals. The lap seal comprises a simple overlap of the
film
without adhesive or heat sealing, but rather electrostatic forces, being
relied upon to
maintain the overlapped edges in contact with one another.
The package is typically subjected to a vacuum and gas flush at the
time of final assembly into a meal kit. If the shrink wrap is airtight, the
vacuum may
cause the end seals to "blow out" or rupture. Accordingly, perforations may be
provided in the shrink wrap film to facilitate evacuation of air from the
package prior
to gas flushing. To facilitate opening, a pull tab may be provided at the lap
seal.
When the product is to be used by the consumer, the lap seal can be readily
separated
by pulling the tab. Tearing of one or both end seals can be initiated at one
or both
ends of the lap seal.
While the above described system has proven commercially
successful, not all packaging lines are capable of forming electrostatic lap
seals.
Some packaging lines are configured to form fin seals rather than
electrostatic lap
seals. Use of shrink wrap film with this type of equipment can be problematic.
One
problem is that the perforations that have been employed in lap seal packages
to
facilitate evacuation of air from the package prior to gas flushing may not be
effective in fin seal packages. Another problem is that opening of the package
may
be more difficult in the absence of a lap seal. The shrink wrap process
reduces the
surface area available on the seals for easy open features of the type that
have been
used with conventional films, i.e., films other than shrink wrap.
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There remains a need for a fin seal/shrink wrap package that can be
used to individually wrap farinaceous food products to limit moisture loss
within a
gas-flushed, sealed compartment.
SUMMARY OF THE INVENTION
The invention generally relates to a packaging system for storage of a
cooked food product to limit migration of moisture from the food product when
the
food product is assembled with other food items in a meal kit. The meal kit
includes
a substantially rigid tray having one or more compartments for receiving the
multiple
pre-cooked and ready-to-eat food items. The multiple food items are deposited
within the tray which then is covered. A vacuum is applied to remove air from
the
headspace surrounding the food items in the compartments, and the compartments
are flushed with a gas. The tray is then hermetically sealed.
One of the food items, a farinaceous food product, is further enclosed
in a second package comprising a shrinkable thinly formed flexible material.
The
package is formed by sealing the flexible material at transverse end seals and
at a
longitudinal fin seal extending between said end seals. After the flexible
material is
sealed, the package is subjected to heat to shrink the flexible material and
form an
essentially closely fitting package around the farinaceous food product. The
package
material is preferably supplied in web form, perforated with a pattern of
openings
that are sized and spaced so that, after heat shrinking of the package
material, the
resulting sizing and spacing of the perforations is sufficient to permit
evacuation of
air from the package without unduly comprising its ability to inhibit moisture
migration. The package also has an easy open feature comprising a tear
initiator at
the fin seal to facilitate tearing of the flexible material to permit a
consumer to
remove the farinaceous food product from the package.
Although the invention is applicable to various farinaceous food
products, it will be described by way of example principally in connection
with
waffles. As used herein, "farinaceous food product" is meant to include any
wheat
flour-based food item, such as waffles, pancakes, bread, buns; tortillas and
cereals.
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BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described in connection with the
accompanying drawings wherein:
FIG. 1 is an exploded perspective view of a meal kit that includes a
packaged farinaceous food product in accordance with the invention,
illustrating
waffles as the farinaceous food product;
FIG. 2 is a perspective view of the packaged farinaceous food product
of FIG. 1 illustrating an easy-open feature on the fin seal in an inverted
orientation;
FIG. 3 is a perspective view of a second embodiment of the
invention in an inverted orientation;
FIG. 4 is a perspective view of a third embodiment of the invention,
illustrating pancakes as the farinaceous food product;
FIG. 5 is a perspective view of a fourth embodiment of the invention,
illustrating hamburger buns as the farinaceous food product; and
FIG. 6 is a perspective view of a fifth embodiment of the invention,
illustrating hot dog buns as the farinaceous food product.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The invention generally is embodied in a packaged food product
included as part of a meal kit. As shown in FIG. 1, the meal kit 10 generally
comprises a tray 12 containing multiple ready-to-eat food items 14, 16, 18,
20, one
of which is a farinaceous food product 14., The tray 12 is made of a
substantially
rigid material and includes one or more compartments 22 to separate and
display the
food items. The food items generally include a pre-cooked meat product 16, a
pre-
cooked farinaceous food product 14, a dessert item 18 and condiments 20 or
other
accompanying food items.
The farinaceous food product 14 may be a breakfast item, such as
waffles; pancakes or french toast, or a bread item, such as a hamburger bun,
hot dog
bun or tortilla. Typical meal kits include mini or bite-sized foods that are
easily
handled by children. The kits therefore generally contain two or more pieces
of such
smaller food items to provide a full serving, rather than one full-sized item.
For
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example, four mini waffle sticks and two large coin sized sausage patties may
be
included in a particular meal kit or three cocktail-sized hot dogs with buns
in another
kit. For convenience, a breakfast meal kit that includes waffles is described
herein.
The waffle formulation preferably is selected to provide a visually
appealing, flavorful waffle. The waffle recipe also is selected to provide a
waffle
that has pleasing physical characteristics when eaten yet is durable enough to
maintain these qualities as best as possible when the waffle is subjected to
refrigeration and storage. The waffle is fully cooked and ready to eat before
packaging.
The pre-cooked food items 14, 16, 18, 20, including the waffles, are
assembled in the various compartments 22 of the tray 12, and a cover 24 is
placed
over the top of the tray to seal the meal kit 10. Preferably, the tray is
hermetically
sealed with the cover and a gas flushed environment provided in the
compartments
to preserve the freshness of the food items and extend shelf life. First, the
headspace
gas in the compartments of the tray is evacuated by vacuum to extract the
oxygen-
containing ambient air. Then the headspace is flushed with an inert gas.
Additionally to preserve the more perishable food items, the meal kit is
refrigerated.
Although the compartment 22 is hermetically sealed, the waffles tend
to lose moisture more quickly than is desirable. With the loss of moisture,
the
overall quality of the waffles diminishes and, more specifically, they may
become
drier, tougher or harder over time. As a result, the shelf life of the waffles
is
shortened relative to that of the meal kit generally.
Separate, individual packaging of the waffles significantly reduces
the rate of moisture loss from the waffles, which, in turn, preserves
freshness and
increases the shelf life of the waffles. By packaging the waffles in a closely
fitted
package, moisture is more evenly retained within the waffles for a longer
period of
time. The waffles preferably are packaged as soon as possible after being
produced
to retain a maximum amount of moisture in the waffles. Pre-packaging of the
multiple waffle pieces that are included in the meal kit provides the added
benefit of
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a unitizing package that improves ease of handling generally, as well as
during the
subsequent packaging of the meal kit.
The waffle package is made with a thinly formed film or sheet
material that shrinks upon exposure to heat. The package material is effective
for
limiting migration of moisture from the waffle and through the package. The
material also is durable enough to withstand handling but is readily torn by a
consumer who uses an easy open feature provided on the package.
The package material preferably is a polyolefin shrink film, or
"shrink wrap." Polyolefin shrink films are known in the art. The package
material
may be selected from the class of polyolefin shrink films. A particularly
preferred
package material is CRYOVACm MY available from Sealed Air Corporation of New
Jersey. This material is a fully coextruded multilayer polyolefin shrink film.
Referring now also to FIG. 2, the preferred package material will be
heat sealable and provide a high integrity seal that will generally withstand
subsequent heat shrinking of the package. The package has a pair of transverse
end
seals 26. The package also has a longitudinal fin seal 28 extending between
the end
seals 26. With respect to the fin seal 28, the package material may be sealed
inward
of the edge 30 of the package material such that two flaps 32 of unsealed
package
material extend beyond the fin seal 28. Alternatively, the package material
may be
sealed out to the edge 30 with no unsealed flap. Each of the end seals 26 and
the fin
seal 28 should be of sufficient width to ensure that the seal is not broken
during
subsequent shrinking of the package material.
The preferred package material also will be of sufficient thickness
and strength to withstand handling, both during packaging and subsequently by
the
consumer. The preferred package material will not be so thick and of such
strength,
however, so as to be completely resistant to tearing when a consumer seeks to
manually remove the package from the waffle using an easy-open feature 34
provided on the package at the fin seal 28. To facilitate tearing of the
package
material by the consumer, the fin seal is adapted with a transverse slit or
notch 36
extending inwardly from the outermost edge 30 of the package material at the
fin
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seal. The slit 36 is of sufficient length to allow the package material to be
torn open
with only minimal force by the consumer. The slit 36 may be reinforced with a
tab
38 positioned on the flap 32 or fin seal 28 to one side of the slit 36. The
package
material may be marked or painted to indicate the location of the slit 36.
The easy open feature 34 preferably is positioned on the flap 32 of the
fin seal 28 rather than on the end seal 26. If the easy open feature is
positioned on
the end seal, the slit may impact the integrity of the seal during subsequent
packaging and handling. For example, during heat shrinking, the slit may
weaken
the seal so that a hole may open in the end seal at the slit as the seal
shrinks.
The easy open feature 34 operates by having the consumer lift the Ilap
32 and grasp it in the vicinity of the tab 38 or at another location
intermediate the slit
36 and the midpoint of the length of the fin seal. When the consumer pulls the
flap
in a direction upward and away from the package, the package material tears
beyond
the interior end of the slit 36 across the surface of the waffle package. The
material
also tears along the innermost edge 40 of the fin seal 28 in a direction away
from the
slit 36.
Alternatively, the fin seal may be provided with a second slit at the
opposite end of the fin seal. The two slits are spaced apart and each
positioned at or
near the ends of the waffle. This two-slit easy open feature operates in a
manner
similar to the one-slit feature described above except that tearing of the
package
material is initiated from both slits so that the package may be opened from
either
end.
In another embodiment, as shown in FIG. 3, the easy open feature 42
may include a tab 44 extending from the fin seal 28 and affixed with an
adhesive to
the package material at the flap 32 or fin seal 28. The tab 44 is highly
visible and
provides a large, accessible appendage for the consumer to grasp, Opening of
the
waffle package is initiated by the consumer grasping the tab 44 and pulling in
a
direction upward and away from the package. The flap 32 then tears at both
slits 36,
tearing across the surface of the waffle package and along the fin seal 28.
Depending on the direction of the force exerted by the consumer in pulling the
tab,
tearing of the package material may occur more predominately at either one of
the
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two SlltS.
In other embodiments, other means to facilitate tear initiation may be
employed, for example, V-notches, perforations, or surface treatments.
The waffles are packaged in the shrink film package material prior to
being assembled in a meal kit. Before packaging of the waffles occurs, the
package
material is mechanically perforated using a perforation wheel as the film is
unrolled.
The size, number and pattern of perforations is selected to avoid unduly high
moisture loss from the finished package through the perforations. The
perforations
46 in the finished package (FIGS. 1 and 2) should be large enough and of
sufficient
number, however, to allow the air contained within the sealed, finished
package to
pass through the perforations in a subsequent evacuation step. If the
perforations
are not properly sized, the package will expand excessively as the vacuum is
pulled,
causing one or more of the seals to open. As a result, the package may expand
so far
as to even explode. Although a microperforated shrink film may be used, these
perforations generally are not sufficiently sized to allow the air to pass
from the
package to prevent the seals from opening.
The perforations preferably are formed by puncturing the web to form
slits between about 1/16 and about I/8 inch in length. No material is removed,
thus
the slits do not have a defined width. Upon heat shrinking of the package
material,
some or all of the slits may open somewhat.
The fully cooked waffles are grouped in a bundle of four waffles and
wrapped in the package material in a forming box. The two sides of the package
material are wrapped around the waffles and the edges positioned adjacent each
other, with the interior surfaces of the package material facing each other.
Then the
fin seal is formed by heat sealing the two sides together along the length of
the
v~raffles. The end seals then are formed by heat sealing the package material
at the
two ends of the waffles. The easy open feature is formed by slitting the fin
seal at
the selected location and applying the tab or other markings.
After the package is formed and sealed, it is passed through a shrink
tunnel where it is exposed to heat. Application of heat shrinks the package
material,
causing it to fit more closely about the waffles. The fin seal 28 is
positioned on the
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bottom of the package in the shrink tunnel, and heat is applied principally to
the top
and sides of the package within the tunnel. This results in relatively low
shrinkage
of the fin seal, so that the slits) 36 and associated tab or indicia on the
fin seal
remain functional after heat shrinking of the package, without the slits)
propagating
to form an opening in the package as a result of the heat shrinking process.
Preferably, the package material is fitted closely about the waffles after
heat
shrinking to maximize retention of moisture in the waffles.
The packaged waffles are subsequently assembled with other food
items for packaging in the tray of the meal kit.
The following describes the dimensions of one example of a finished
waffle package embodying the features of the present invention. The bundle of
waffles are from about 3 '/, to about 3 '/2 inches long, from about 2 to about
2 '/4 wide
and from about 1 to about 1 '/4 inches high. The fin seal is from about '/4 to
about '/~
inches wide and the flap at the fin seal is from about '/4 to about '/z inches
wide. The
slit of the easy open feature is from about'/4 to about'/Z inches long and is
positioned
on the fin seal from about'/4 to about 1 inch inward of the end of the waffle.
'The
perforations are spaced approximately'/4 inches apart in lines extending
longitudinally of the package which are spaced approximately 1 '/4 inches
apart. The
perforations may be of any shape but preferably are from about 1/16 to
about'/e inch
at their greatest dimension.
In other embodiments of the present invention, different farinaceous
food products are packaged in accordance with the invention. For example, the
farinaceous food product may be pancakes (FIG. 4), hamburger buns (FIG. 5) or
hot
dog buns (FIG. 6).
Numerous modifications to the package may be possible to further
improve the moisture retention and handling CharactarigtiC~ of the package,
'thug,
modifications and variations in practice of the invention are expected to
occur to
those skilled in the art upon consideration of the foregoing detailed
description of the
invention. Although a preferred embodiment has been described above and
illustrated in the accompanying drawings, there is no intent to limit the
scope of the
invention to this or any other particular embodiment. Consequently, any such
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modifications and variations are intended to be included within the scope of
the
following claims. The invention is described further and pointed out by the
following claims.
Ducumcut Nu. 205889
