U.S. patent application number 12/404274 was filed with the patent office on 2009-11-26 for high pressure pasteurizable/ultra-high pressure sterilizable food processing container and method.
This patent application is currently assigned to Portage Plastics Corporation. Invention is credited to Gregg S. Lewis.
Application Number | 20090291174 12/404274 |
Document ID | / |
Family ID | 41342311 |
Filed Date | 2009-11-26 |
United States Patent
Application |
20090291174 |
Kind Code |
A1 |
Lewis; Gregg S. |
November 26, 2009 |
HIGH PRESSURE PASTEURIZABLE/ULTRA-HIGH PRESSURE STERILIZABLE FOOD
PROCESSING CONTAINER AND METHOD
Abstract
A method and container capable of withstanding ultra-high
pressure sterilization or pasteurization and being used as a retail
package. The container includes at least one deformable pressure
absorbing fold channel integrally formed therein enabling the
container to undergo UHP processing and return substantially to its
prior shape. In one embodiment, the container has at least one
sidewall with such a fold channel. In a preferred embodiment, the
package also has a bottom wall with a fold channel. The container
is thermoformed of a sheet that includes at least one oxygen
barrier layer and includes a peelable oxygen barrier film covering
a container opening. In a preferred method, the container has a
plurality of sidewalls with a fold channel therebetween and a
bottom with a fold channel thereabout that accommodates compression
between 5% and 25% without showing visible damage when subjected to
pressures of between 70 ksi and 120 ksi.
Inventors: |
Lewis; Gregg S.; (Middleton,
WI) |
Correspondence
Address: |
BOYLE FREDRICKSON S.C.
840 North Plankinton Avenue
MILWAUKEE
WI
53203
US
|
Assignee: |
Portage Plastics
Corporation
Potage
WI
|
Family ID: |
41342311 |
Appl. No.: |
12/404274 |
Filed: |
March 13, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61036327 |
Mar 13, 2008 |
|
|
|
Current U.S.
Class: |
426/399 ;
206/524.3; 220/666 |
Current CPC
Class: |
B65B 55/18 20130101;
B32B 2307/7244 20130101; B65D 81/2053 20130101; B32B 27/306
20130101; B32B 7/06 20130101; B32B 27/08 20130101; B32B 2435/02
20130101; B32B 2250/24 20130101; B32B 2307/7246 20130101; B32B
27/304 20130101; B32B 7/12 20130101; B32B 2307/7265 20130101; B32B
2307/308 20130101; B65D 1/40 20130101; B32B 1/02 20130101; B32B
2307/71 20130101; B32B 2307/734 20130101; B32B 2307/748 20130101;
B32B 27/32 20130101; B65D 79/005 20130101; B32B 2439/70
20130101 |
Class at
Publication: |
426/399 ;
206/524.3; 220/666 |
International
Class: |
B65B 55/02 20060101
B65B055/02; B65D 85/00 20060101 B65D085/00; B65D 6/16 20060101
B65D006/16 |
Claims
1. A container for use in high pressure sterilization comprised of
at least one sidewall and a fold region formed of a multi-layer
sheet having an oxygen barrier and a oxygen barrier film sealing an
opening thereof.
2. The high pressure sterilizable container of claim 1 wherein the
multi-layer sheet is comprised of a layer of an oxygen barrier
material and at least one layer of a polymer.
3. The high pressure sterilizable container of claim 2 wherein the
multi-layer sheet comprises a plurality of outer layers of
polypropylene and an inner layer comprised of an oxygen barrier
material.
4. The high pressure sterilizable container of claim 3 wherein the
oxygen barrier material comprises one of Ethylene Vinyl Alcohol and
Polyvinylidene Chloride.
5. The high pressure sterilizable container of claim 1 wherein the
sidewall and fold region are integrally formed of the multi-layer
sheet forming a container of one piece, substantially homogenous
and unitary construction to which the oxygen barrier film is
attached.
6. The high pressure sterilizable container of claim 5 wherein the
fold region has an arcuate transverse cross-section, is elongate,
and extends generally longitudinally.
7. The high pressure sterilizable container of claim 6 comprising a
plurality of sidewalls with a fold region extending
therebetween.
8. The high pressure sterilizable container of claim 7 comprising a
plurality of pairs of sidewalls and wherein there is a fold region
extending therebetween that comprises a fold channel.
8. The high pressure sterilizable container of claim 5 wherein the
fold region extends generally transversely.
9. The high pressure sterilizable container of claim 9 further
comprising a bottom wherein the fold region extends along a portion
of the bottom.
10. The high pressure sterilizable container of claim 10 wherein
the fold region comprises a channel that extends about a portion of
the bottom.
11. A high-pressure container for use in food sterilization
comprising: a bottom comprised of a first integrally formed fold
region; a plurality of sides extending upwardly from the bottom
comprising a second integrally formed fold region; and wherein the
container is configured to buckle under the application of high
pressure of at least 70 kpsi and return substantially to its
initial shape after application of the pressure.
12. The container of claim 11 wherein the container is composed of
a multi-layer sheet material.
13. The container of claim 12 wherein the multi-layer sheet
material includes at least one layer of a co-polymer adapted to
serve as a liquid barrier.
14. The container of claim 13 wherein the co-polymer comprises
polypropylene.
15. The container of claim 13 wherein the multi-layer sheet
material includes at least one layer of an oxygen barrier
material.
16. The container of claim 15 wherein the oxygen barrier material
comprises EVOH.
17. The container of claim 11 further comprising a removable film
adapted to be secured to the upper surface of the container and
configured to serve as an oxygen barrier.
18. The container of claim 11 further comprising a removable lid
secured to the upper surface of the container.
19. A method of high pressure sterilization of food product
comprising the steps of: providing a container having a sidewall
and at least one fold region; packaging perishable food product in
the container; placing the container in a vessel configured for
high pressure sterilization; filling in the vessel with water; and
pressurizing the vessel so as to sterilize the food product to a
pressure of at least 70 kpsi; wherein the container is configured
to buckle during the pressurization of the vessel and return
substantially to its initial shape after the pressurizing.
20. The method of claim 19 wherein the fold region comprises a
channel configured to buckle during the pressurizing of the vessel.
Description
CROSS REFERENCE
[0001] This application claims priority under 35 U.S.C. .sctn.
119(e) to U.S. Provisional Patent Application No. 61/036,327, filed
Mar. 13, 2008, the entirety of which is hereby expressly
incorporated by reference herein.
FIELD
[0002] The present invention relates to a package for food
processing, preferably a container, that is configured to withstand
the application of a substantially high pressure for the purpose of
sterilization or pasteurization of the contents therein while
maintaining its structural integrity.
BACKGROUND
[0003] High pressure pasteurization and ultra-high pressure
sterilization have been used in the past to treat foodstuffs and
other organic material to inactivate bacteria, yeast, mold, and the
like. Typically, the product being treated is packaged in a pouch
that is subjected to extremely high isostatic pressures for a
certain period of time that is sufficient to decrease such
contamination by sterilizing the product.
[0004] In ultra-high pressure sterilization (UHP) or high pressure
pasteurization (HPP), the product being treated is typically
packaged in a pouch that is subjected to pressures within a
pressure vessel or the like of between 70,000 PSI and 150,000 PSI
for a sufficient length of time to inactivate such pathogens. The
time under pressure typically ranges from at least three minutes to
as long as 15 minutes or more. The process is performed an ambient
temperature that typically is no greater than about 140.degree. F.
(60.degree. C.).
[0005] Prior to UHP/HPP processing, the pouches are loaded with
product by inserting the product through a seal that is thereafter
closed. Unfortunately, as a result of the extremely high pressures
used during UHP processing, the pouch seals can become compromised
such that pathogens and the like can easily enter the pouch
contaminating it. When this happens, it obviously defeats the
purpose of UHP processing requiring the compromise pouch to be
disposed of.
[0006] While there have been many improvements directed to such
pouches, they mainly concern reinforcing the seal by enclosing the
seal in a shield or a hood to prevent the seal from being
compromised during UHP processing. Unfortunately, this
significantly increases pouch cost.
[0007] Even when the pouches are not compromised during UHP
processing, there are disadvantages to the use of pouches. For
example, pouches are not always well suited for being displayed in
a retail setting at a store, a gas station or the like. In
addition, some types of foodstuffs are not particularly well-suited
for pouch packaging.
[0008] In the past, it is believed that attempts at using
substantially rigid, self-supporting plastic containers have not
been heretofore successful because the high pressure employed
during UHP processing so greatly deforms the container that any
attempt to provide an oxygen impermeable seal cannot be adequately
maintained. In addition, the resulting deformation that occurs
during UHP processing, so adversely affects the appearance of the
container that it simply not suitable for retail display.
[0009] What is needed is a substantially rigid and self-supporting
plastic container that is capable of maintaining and oxygen
impermeable barrier after UHP processing. What is also needed is a
substantially rigid and self-supporting plastic container that is
capable of maintaining an oxygen impermeable barrier after UHP
processing while also maintaining its aesthetic appearance so as to
be displayable in a retail setting. What is still further needed is
such a container that can be used with a removable lid.
SUMMARY
[0010] The present invention relates to a container, that can be in
the form of a tub or the like, which includes at least one sidewall
and a bottom wall interconnected in a manner that defines a food
product holding cavity and which is deformable under ultra high
pressure (UHP) processing at pressures of between 70,000 PSI and
120,000 PSI while being able to substantially return to pre-UHP
processing shape. The container has an opening through which food
product is inserted and which employs a film covering the opening
that seals food product in the container prior to UHP
processing.
[0011] The container has at least one side deformation facilitating
fold region integrally formed in it that is of arcuate construction
that facilitates deformation during UHP processing and which
enables the container to snap back to substantially its original
shape after processing is completed. The container can also have at
least one bottom deformation facilitating fold region formed in it
that facilitates deformation during UHP processing and which
enables the container to snap back to substantially its original
shape after processing is finished. In a preferred embodiment, each
fold region is a channel having an arcuate transverse cross
sectional configuration.
[0012] Such a container is thermoformed of a sheet having a
plurality of pairs of layers with at least one of the layers being
an oxygen barrier that keeps oxygen from reaching food product in
the container after UHP processing. In one embodiment, the sheet
includes an oxygen barrier layer sandwiched between an inner and
outer layer. In one preferred embodiment, the multi-layer sheet
includes a layer of Ethylene Vinyl Alcohol (EVOH) sandwiched
between layers of a co-polymer, such as a polypropylene copolymer.
The multi-layer sheet can further include additional layers
including one or more tie or adhesive layers. The film also
includes an oxygen barrier, such as EVOH, that keeps oxygen from
reaching food product in the container after UHP processing with
the film sealed to the container about the periphery of its
opening. In a preferred embodiment, the sidewalls, bottom and fold
channels define a container of one-piece, unitary and substantially
homogenous construction.
[0013] During UHP processing, a plurality of containers each filled
with food product and sealed with film are disposed in a pressure
vessel and subjected to pressures between 70 kpsi and 120 kpsi
causing deformation of between 5% and 25% during sterilization.
After removal of the ultra high pressure, the containers snap back
or expand back to substantially the same size as prior to
processing. Thereafter, a lid can be attached such that the package
containing the container, food product, film and lid are ready for
retail display and sale.
[0014] In use, the lid is removed and the film peeled away to
access the sterilized food product within the container. Such food
product keeps at least 45 days. In one preferred embodiment, such
food product keeps between 45 and 60 days.
DRAWING DESCRIPTION
[0015] The drawings illustrate the best mode currently contemplated
as practicing the present invention. One or more preferred
exemplary embodiments of the invention are illustrated in the
accompanying drawings in which like reference numerals represent
like parts throughout and in which:
[0016] FIG. 1 is a top perspective view taken of a container of the
present invention that is configured for use in UHP/HPP
processing;
[0017] FIG. 2 is a bottom perspective view of the container of FIG.
1;
[0018] FIG. 3 is an elevation view of one side of the container of
FIG. 1 with a portion of a sidewall of the container broken away to
show food product received in the container;
[0019] FIG. 4 is a plan view of the a bottom of the container of
the present invention;
[0020] FIG. 5 illustrates a second perspective view of a preferred
embodiment of a container for holding food product during high
pressure sterilization/ultra-high pressure pasteurization and
enabling it to be thereafter sold in a retail outlet;
[0021] FIGS. 6A and 6B are fragmentary cross section views of the
container sidewall taken along line 6-6 of FIG. 5 illustrating
preferred container sidewall layer configurations;
[0022] FIG. 7 is a fragmentary cross sectional view of a pair of
container sidewalls and a UHP fold channel before application of
pressure;
[0023] FIG. 8 is a fragmentary cross sectional view of the pair of
container sidewalls and fold channel shown in FIG. 7 during
application of pressure;
[0024] FIG. 9 is a perspective view of a lid for use with the
container of the present invention; and
[0025] FIG. 10 illustrates a stacked arrangement of containers of
FIG. 1 used in mass UHP processing within a chamber of a UHP
processor.
[0026] Before explaining each embodiment of the invention in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of the components set forth in the following description or
illustrated in the drawings. The invention is capable of other
embodiments or being practiced or carried out in various ways.
Also, it is to be understood that the phraseology and terminology
employed herein is for the purpose of description and should not be
regarded as limiting.
DETAILED DESCRIPTION
[0027] Turning now to FIGS. 1-4, a container 20 for use in high
pressure processing of food product 40 (FIG. 3) is shown. Container
20 is configured for use during ultra-high pressure (UHP)
sterilization/pasteurization of the food product 40 within the
container 20. In operation, container 20 containing food product 40
is subjected to substantially high pressures whereby the food
products contained therein are sterilized and/or pasteurized to
provide substantially longer shelf life for the food products 40.
During UHP processing, the container 20 and food product 40
contained therein are subjected to isostatic pressure such that the
pressure that the container 10 and food product 40 therein is
subjected to is substantially uniform or the same in all
directions. Thereafter, with the container 20 remaining sealed
after UHP processing, the container 20 is shipped to a store or the
like where it is available for sale providing a point-of-purchase
food product package having significantly extended shelf-life.
[0028] Container 20 of the present invention includes four sides 22
defining a cavity 24 therebetween. Container 22 further includes an
upper surface 26 having a lip 28 disposed thereon and a flange 29
extending therefrom. The upper surface 26 further defines an
opening 27 therein for receiving food product in the cavity 24. The
configuration of the upper surface 26, namely lip 28 and flange 29,
are generally configured enable the container 20 to be nestable
with other containers 10 of the kind of the present invention. The
flange 28 is configured to provide a seating surface for other
nesting containers. Container 20 further includes a bottom surface
41 for supporting food product. In addition, container 20 further
comprises four generally vertically extending fold regions 42
disposed between each of sides 22 and a generally horizontally
extending fold region 44 disposed along the outer edge of bottom
surface 41. The side fold regions 42 and bottom fold region 44 are
configured and shaped to allow the container 22 to withstand
relatively high pressures during the UHP process.
[0029] A film or other seal 46 (FIG. 3) is provided for covering
the container opening 27 and upper surface 26 during the UHP
process and to serve as an oxygen barrier. Such a film 46 therefore
is or includes an oxygen barrier, such as Ethylene Vinyl Alcohol
(EVOH) or the like, to prevent oxygen from entering the container
20 during the UHP process. The film 46 remains attached after the
UHP process to provide to prevent oxygen from entering the
container 20 and coming into contact with the sterilized food
product 40 inside the container 20. The film 46 generally includes
an adhesive disposed on one side thereof for application to the lip
28 of upper surface 26. Such an adhesive can be a heat or pressure
sensitive adhesive that forms a layer or coating on the side of the
film 46 that is applied onto an outer top surface of the lip 28 of
container 20. The film 46 can also be a heat and pressure sensitive
adhesive or other such adhesive capable of operating as intended
for use with the present invention. Using such an adhesive to
attach the film 46 to the container 20 enables the film 46 to be
peelable from the upper surface 26 of the container 20.
[0030] A plurality of fold regions 42 are of concave construction
and configured to provide container 20 with superior resiliency
under high pressure during UHP processing of between 75 kpsi and
250 kpsi. During the UHP processing, the fold regions 42 are
configured to allow for a predetermined amount of buckling. In
addition, sides 22 are configured to be generally compressed and
collapse during application of such high pressures during the UHP
process. After completion of the UHP process, the vertical fold
regions 42 and sides 22 are configured to snap back into their
original positions without suffering any damage thereto.
Preferably, however, the fold regions 42 are not permitted to
buckle to a completely inside out configuration, but rather, the
regions 42 merely indent or elastically deform a relatively small
amount during application of pressure during UHP processing.
[0031] Bottom fold region 44 likewise can be provided to allow for
buckling up during the pressurization of container 20. As such,
upon the release of the pressure therefrom upon the completion of
UHP processing, region 44 is configured to snap back into its
initial position without causing damage thereto. The dimensions of
the bottom fold region 44 are partially driven by the depth of the
cutter utilized for machining a mold (not shown) for forming the
container 20. The bottom fold region 44 dimensions must be of a
certain range depending on the size of the container 20 so as to
enable the container 20 to buckle an appropriate amount of under
pressure during UHP processing. Specifically, for example, if the
bottom fold region is too large, the region 44 will not buckle as
needed.
[0032] As is shown in the drawing figures, each fold region 42 is
of recessed construction, preferably being an elongate fold channel
43. In the currently preferred embodiment shown in the drawing
figures, each fold region 42 is of concave construction with each
fold region 42 being defined by an elongate radiused channel 43
formed in accordance with that discussed above. The same is true
for the elongate radiused channel 45 that defines bottom fold
region 44 encompassing the bottom 41 of the container 20.
[0033] One or more of fold regions 42 can be of radiused
construction as is shown in the drawing figures being a channel 43
having a radius, r, before UHP processing which ranges between 1/4
inch and about 5/8 inch, depending on factors such as container
size, container thickness, container mold manufacturing
constraints, and the like. In addition, with regard to fold region
46, the preferred minimum radius for the bottom fold channel 45 is
approximately 1/4 inch, and the preferred minimum radius is
typically driven by the inherent limitations of the cutting tool
utilized for machining the container 20. It is presently
contemplated that the radiused bottom fold channel 45 also has a
radius of between about 1/4 inch and about 5/8 inch but can be
larger for containers of a size greater than discussed herein. If
desired, one or more of the fold channels 43 and/or 45 can be of
convex or outwardly bowed construction.
[0034] The side fold channels 43 and bottom fold channel 45 each
comprise a particular geometry configured to provide the container
10 holding food product 30 with the ability to substantially deform
by compressing between 5% and 25% during the pressurization process
while maintaining the ability to expand back to its initial shape
thereafter. Further, the container 20 is composed of a resilient
material configured to maximize the ability of the container 20 to
withstand the pressurization process.
[0035] During UHP processing, at least part of a gaseous space 50,
referred to as headspace 50, between the food product 40 and the
overlying film 46 sealed to the container 20 also compresses as the
container 20 compresses. In fact, a container 20 constructed in
accordance with the present invention deforms, typically by
compressing, under pressure causing compressible gas in the
headspace 50 to go into solution in the food product 40. Therefore,
a container 20 constructed in accordance with the invention can
compress during UHP processing in a manner that accommodates the
compressibility of any gaseous headspace 50, including the gas in
the headspace 50 going into solution in the food product 40,
without plastically deforming the container 20, without rupturing
the film 46, or without causing the film 46 to peel away from the
container 20.
[0036] As a result, a container 20 constructed in accordance with
the present invention holds food product 40 during UHP processing
while also advantageously serving as a point-of-sale food product
package. It is also advantageous that the container 20 undergoes
UHP processing without substantial damage such that the container
20 shows virtually no visible sign of having undergone UHP
processing. In at least one preferred container embodiment, a
container 20 constructed in accordance with the present invention
suffers no damage after undergoing UHP processing such that the
resultant package shows virtually no externally visible sign of
having underwent UHP processing.
[0037] The container 20 of the present invention is configured to
allow for the sterilization/pasteurization of food product 40
contained therein while maintaining the overall integrity of the
container itself. Typically, containers 20 of the present invention
are loaded into a vessel 51 (FIG. 10) that is then flooded with
water 53 and then uniformly and highly pressurized. The
pressurization serves to kill any bacteria or other such organisms
that may lead to food spoilage to thereby lengthen the effective
shelf life of the food product 40 stored in container 20.
[0038] The container 20 of the present invention is preferably used
to sterilize and lengthen the effective shelf lives of fresh foods
such as vegetables and meats. In a preferred embodiment of the
present invention, the shelf lives of foods stored and
sterilized/pasteurized using container 20 is at least thirty days
and preferably between forty five days and ninety days.
[0039] With reference to FIGS. 6A and 6B, the container 20 is
composed of a multi-layer sheet 70a or 70b adapted to provide a
high-pressure barrier package. Such sheeting is commonly used in
aseptic, "hot fill" and retort packaging applications. In a
preferred embodiment of the present invention, container 20 is made
from an extruded seven or nine-layer package sheeting having a very
strong oxygen and moisture vapor resistant characteristics to
provide a relatively long shelf life for items packaged therein. In
another preferred embodiment, the container 20 is formed from a
five layer sheet.
[0040] With reference to FIG. 6A, the multi-layer sheet 70a or 70b
includes a pair of outer layers 72 and 74 to provide the container
20 with a moisture barrier. These layers 72 and 74 also help
provide structural integrity to the container 20 after
thermoforming into the desired shape shown in the drawing figures.
Outer layers 72 and 74 are preferably comprised of a copolymer such
as, for example, polypropylene. An adhesive or tie layer 76 and 78
is provided on one side of each of the outer layers 72 and 74. An
oxygen barrier layer 80 is generally disposed between the two
adhesive layers. The oxygen barrier layer 80 preferably comprises a
layer of Ethylene Vinyl Alcohol (EVOH). The oxygen barrier layer 80
may, alternatively comprise another compound capable of providing
an oxygen barrier and withstanding the substantial pressures
applied thereto. For example, Polyvinylidene Chloride (PVDC) or
Saran may alternatively be used. In addition, other materials may
be added to the multi-layer sheet 70a to enhance the rigidity
thereof or to improve other such aspects. In a preferred
embodiment, the sidewalls 22, bottom wall 41 and fold channels 42
and 44 define a container 20 of one-piece, unitary and
substantially homogenous construction.
[0041] The multi-layer sheet 70b shown in FIG. 6B is similar to the
sheet 70a shown in FIG. 6A but further includes a plurality of
additional layers 82 and 84 that can be of polymeric construction,
such as a core layer made of a homopolymer or the like. Where of
nine-layer construction, there can be additional layers between
layers 74, 84 and 72, 82 or between layers 80, 84 and 80, 82.
[0042] In a currently preferred container embodiment shown in FIG.
5, the container 20 is integrally formed so as to have both
vertical fold channels 43 and a bottom fold channel 45. Such a
container 20 is thermoformed from a multi-layer sheet, e.g., sheet
70a or 70b, having at least one oxygen impermeable layer 80 that
provides an oxygen barrier during HPP processing of food product 40
in the container 20. In a preferred manufacturing method, the
container 20 is thermoformed from a sheet 70a or 70b having a
plurality of pairs, i.e., at least three, layers with at least one
of the layers being an oxygen impermeable layer 80, such as the
aforementioned EVOH discussed above. A preferred thermoformable
multi-layer sheet 70a or 70b has a plurality of resilient and
deformable or compressible polymeric layers, each of which can be a
copolymer, sandwiching an oxygen impermeable layer. One preferred
thermoformable sheet material is disclosed above has having a layer
of EVOH sandwiched between a pair of layers of polypropylene. There
can be an adhesive layer between the EVOH and each sandwiching
layer. If desired, as discussed above with regard to FIGS. 6A and
6B, the sheet from which the container 10 is thermoformed can have
additional layers.
[0043] The thickness of the above-described sheet 70a or 70b from
which the container 20 is thermoformed varies with container size
or capacity. For example, a container 20 having a size ranging
between eight ounces and thirty-two ounces has a thickness ranging
from twenty-five mils to forty mils. Such a thickness
advantageously helps enable the container 20 to withstand HPP food
processing at pressures ranging from 80 kpsi all the way up to 120
kpsi. In one HPP food processing method, the container 20 holding
food product 40 is processed at a pressure of about 87 kpsi.
[0044] In the preferred embodiment shown in the drawing figures,
each sidewall 22 is substantially the same size having
substantially the same dimensions. The bottom wall 41 can also be
of substantially the same size, such as where the container 20 is
of substantially square, cube-shaped construction. If desired, each
sidewall and bottom wall can deviate from being square, such as by
being rectangular. Each sidewall 22 is separated by a corner
section that is formed to provide a fold region 42 about which
adjacent and opposed corners 54, 56 (FIGS. 7 and 8) of adjacent
sidewalls 22 fold and move toward each other or come together
during UHP processing.
[0045] In a method of using such a container 20 in UHP food
processing, formed containers 20 can be stacked, such as for
shipment to a processing plant where each container is filled with
food product 40 and then sealed with a film 36 that is oxygen
impermeable or which has at least one oxygen impermeable layer. In
a preferred embodiment, each container 20 is labeled before UHP
processing with a product label that facilitates point-of-sale
retail distribution and sale of such containers 20. Food product 40
for which the container 20 and method of use is well suited include
fresh foods which cannot be sterilized or pasteurized using
conventional high temperature sterilization or pasteurization.
Examples of types of food product well suited for UHP food
processing in a container 20 constructed in accordance with the
present invention include meat, raw fish, such as sushi, salsa,
hummus, tomatoes, tomato paste, and guacamole. Other types of food
product easily damaged by application of high temperatures can also
be packaged and processed in such a container 20.
[0046] An example of a preferred film 36 is constructed in
accordance with that discussed above. Such a film 36 includes a
heat and/or pressure activated adhesive so as to be sealed to a top
surface 26 of the lip 28 in a manner that provides a peelable film
covering. An example of a suitable film is a commercially available
heat-sealable lid stock that is of oxygen impermeable construction
such as by having an oxygen barrier layer like EVOH.
[0047] With reference to FIG. 10, thereafter, a plurality of pairs
of sealed and filled containers 20 are placed in a rack 90 (shown
in phantom in FIG. 10) that is inserted into a vessel 51 in which
water 53 is introduced under pressure during UHP food processing.
In a preferred implementation of a method of UHP food processing
using a sealed and filled container 20 constructed in accordance
with the present invention, a plurality of pairs of sealed and
filled containers 20 are placed in rack 90 and inserted into a
generally horizontally disposed high pressure vessel 51 of an UHP
processing apparatus 55. Thereafter, water 53 is introduced into
the vessel 51 under pressure causing each container 20 and the food
product 30 sealed therein to be subjected to pressures ranging
between 70 kpsi and 120 kpsi at a suitable temperature for a
suitable period of time to achieve UHP processing of the food 40
within each container 20.
[0048] With reference to FIG. 7, prior to application of such high
pressure, each container sidewall 22 and each corresponding fold
channel 44 is not deformed with the adjacent opposed sidewall
corners 54, 56 spaced apart from each other a first distance,
d.sub.1. With reference to FIGS. 5 and 8, during application of UHP
high pressure, each container 20 and the food product 40 within
each container 20 deforms by being compressed at least 2%. The
remainder of the compression is believed to be a function of the
volume of headspace 50 between the food product 40 and the type of
food product 40 as it pertains to compressible matter in the food
product 40 (as most food is made mostly of incompressible water
plus a small percentage of other constituents at least some of
which are compressible). For example, it is estimated that food
product 40 of the type discussed herein is between 5% and 10%
compressible with its compressibility typically being a factor of
its water content.
[0049] As previously mentioned, pressure is applied for a long
enough period of time to kill bacteria and/or viruses in the food
product 40 in the container 20 sterilizing it and/or pasteurizing
it. As pressure is applied, each sidewall 22 bows inwardly and the
associated fold channel 43 folds or buckles slightly in the
exemplary manner shown in FIG. 8 helping to accommodate for the
pressure while preserving the ability of the container 20 to
substantially return to its pre-processing shape and appearance.
During application of UHP pressure, adjacent opposed sidewall
corners 54, 56 are displaced toward each other causing the fold
channel 43 to fold or buckle at least slightly reducing the
distance, d.sub.2, therebetween to a distance that is less than
d.sub.1. For example, where each fold one of the fold channels 43
is of arcuate or radiused construction, the radius of curvature
decreases during application of pressure from its radius of
curvature when relaxed prior to application of pressure. The same
thing happens to the bottom fold channel 45 prior to and during
application of pressure.
[0050] During UHP processing, at least part of the headspace 50
also compresses as the container 20 compresses. Depending on the
type of food product 40 in the container 20, the amount of
headspace 50 it required during packaging, and the UHP processing
pressure, the container 20 compresses between about 5% and 25%. For
example, in one embodiment where salsa or tomato food product is
the food product 40 in the container 20, the container 20
compresses about 15% where the UHP processing pressure is about 87
kpsi. During processing, gas in the headspace 50 responds to being
compressed by itself compressing with at least some of the gas in
the headspace 50 diffusing into the food product 40. Compression of
the container 20, gas in the headspace 50 and compressible matter
in the food product 40 occurs as a result of the novel construction
of the container 20 without plastically deforming the container 20,
rupturing the film 46, or causing the film 46 to peel away from the
container 20.
[0051] Thereafter, the pressure is removed causing each container
20 and the food product 40 within each container 20 to expand back
substantially to the size each was prior to UHP processing (e.g. to
the shape depicted in FIG. 7) without the exterior showing
virtually any visible damage. Where gas in the headspace 50 has
diffused into the food product 40 during UHP processing, it can and
typically does come out of the diffusion back into the headspace
50. After processing is finished and all of this occurs, the
container 20 has no crinkles, no indentions and has substantially
the same shape as prior to UHP processing. Additionally, there is
neither rupture of the film 46 nor any breach of the seal between
the film 46 and the container 20. In one preferred method
implementation, the container 20 has no white areas indicative of
plastic deformation thereby indicating that only elastic
deformation took place during compression of the container 20
during UHPP processing.
[0052] In one preferred method implementation, the container 20 and
food product 40 within each container 20 is subjected water 53
pressurized to a pressure of about 87 kpsi during UHP processing
causing the container 20 to compress about 15%. After the pressure
is removed, each container 20 returns to the shape it previously
had prior to UHP processing such that only elastic deformation took
place during UHP processing. In another preferred implementation,
each container 20 and the food product 40 within each container is
subjected to isostatic pressure of between 70 kpsi and 120 kpsi
causing each container 20 and the food product 40 to compress
between 5% and 25%.
[0053] After UHP processing, each container 20 is shipped to a
place of retail sale, such as a grocery store, gas station,
convenience store or the like where it is placed on sale. A
purchaser buying a container 20 peels away the film 46 to access
the food product 40 within the container 20. As a result of UHP
processing, the shelf life of the food product 40 within each
container 20 is at least 45 days. In one preferred embodiment and
method implementation, shelf life ranges between 45 days and 90
days.
[0054] Referring now to FIG. 9, a lid 75 configured for placement
over the top upper surface 26 of the container 20 is specifically
configured for use with the present invention. In one preferred
embodiment, the lid 75 is secured to the upper surface 26 of the
container 20 after completion of the high pressure application to
the container 20. Such a lid 75 is attached to the container 20 and
overlies the film 46 thereby serving as a protective barrier that
protects the integrity of the film 46 (and the oxygen impermeable
seal it provides). Such a lid 75 can be pre-labeled or a label can
be applied after placement of the lid 75 on the container 20. Such
a lid 75 is complementarily configured so as to be snapped onto the
container 20 having a top wall 77 that overlies the film 46 when
the lid is snapped on, first and second side walls 79 and 81 that
engage the container top surface 26, and an outwardly extending
flange 83. Such a lid 75 is made of a polymeric material, such as a
thermoformable plastic or the like, but can be made of any other
suitable material.
[0055] Various alternatives are contemplated as being within the
scope of the following claims particularly pointing out and
distinctly claiming the subject matter regarded as the invention.
Thus, it is also to be understood that, although the foregoing
description and drawings describe and illustrate in detail one or
more preferred embodiments of the present invention, to those
skilled in the art to which the present invention relates, the
present disclosure will suggest many modifications and
constructions, as well as widely differing embodiments and
applications without thereby departing from the spirit and scope of
the invention.
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