Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ 1336147
SYSTEM FOR PACKAGING PERISHABLE
LIQUIDS IN GA~LE TOP CARTONS
FIELD OF THE INVENTlON
Thts invention relates to the shelf stable packaging
of perishable ~uices and other perishable liquid products tn
hermétically se`aled gable top cartons acceptable to the
consumer. A packaged product ts satd to be shelf stable when
5 it retains its desirable qualtties for an extended pertod of time
without refrigeration .
BACKGROUND OF THE lNVENTlON
The selection of appropriate containers and processes
for packaging a particular liquid food product presents the
packer with various options from which to choose. Against these
]0 must be considered numerous factors. These include cost of the
container and packaging process, structural tntegrity and weight
of the package, handling convenience for the packer and
convenience for the consumer i.e., can the container be tightly
packed? Is tt fragile? The packer must also consider the
15 distribution network and infrastructure available in the market
- sought to be served: is refrigeration available, if not, the
packaged product must be rendered shelf stable?
A packa~e which is too costly in relation to the
value of the product itself or which is inconvenient in some
20 respect for the consumer will meet with market resistance and
likely fail to win a sufficient degree of acceptance to be
commerctDlly viable.
Tradittonally juices have been packed in cans and
`~ glass bottles. The technology applicable to these packages is
25 well known. Juices packed tn these containers may be kept
unrefrigerated for extended periods provided that these products
and their containers ha ve been sterilized ond hermetically
sealed tn order to prevent entry of bacteria.
These containers have achieved wide acceptance
throuQh use. They may be easily sterilized and sealed
effectively. They tolerate both tnternal vacuum and posttive
pressure. Closures such as twist off lids for bottles are
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a~:~ept~,ble to consumers because they are easy to operate and
may be used to close the bottles effectively after first opening.
These containers resist high temperatures end thus may be
sterilized at usual temperatures without deteriorating their
5 struct ura I qu alities .
Among the disadvantages of glass bottles and cans
are cost and the weight which they add to the product. Also,
because of their shape, cans and bottles cannot be tightly
packed, In the ca se of bottles their relative fragility is also a
10 dis a d v a nta ge .
More recently greater use of so-ca lled flexible
containers has been made for the packaging of liquid food
products. These include paper-based containers, molded plastic
containers and plastic pouches.
Two types of paper-based flexible containers have
become widely accepted, the gable top carton and the brick
pack. The gable top carton has been extensively used for
packa~ing refrigerated non-shelf stable liquid products such as
milk and other dairy products and fruit juice products. The
20 brick pack, so called because of its shape, has been extensively
used in association with an aseptic packing process for fruit
juices packaged for shelf stability and which therefore do not
re qu i re re fri g er a tion .
The gable top carton is relatively inexpensive and
25 light wei~ht. Moreover, because of its planar sides it can be
tightly packed for shipping and storage. The gable top carton
~1 enjoys wide acceptance in the publtc for its ease of storage and
handling after opening and for its spout which pours well and
re-closes effectively even to the extent of permitting the contents
30 to- be lightly shoken without spilling. One disadvantage of the
gable top carton, when compared with glass bottles, is the
difficulty encountered by many consumers in opening the carton
for the first time. This problem has been larsely overcome in
the dairy ond fruit ~uice industry by simply weakening the seal
35 at the spout.
A previously proposed method of weakening the spout
- is described in U.S. Patent No. 3,116,002, wherein it is
suggested that a non-adherent material "abhesive" be applied to
selected areas near the spout in order to reduce the
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1336147
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plastic-to-plastic bond formed during the sealing process.
The method adds to the cost of the carton and quality control
as to the precise placement of the adhesive is difficult to
achieve during packing.
While the otherwise desirable goal of achieving a
strong hermetic seal is defeated the consumer has become
accustomed to the fact that dairy products and juices packed
in this way must be kept refrigerated and have only limited
shelf lives. Because of this practice of weakening the seal
to please the consumer, from a consumer acceptance point of
view, it is not possible to successfully market a juice in a
gable top carton unless the spout is relatively easy to open.
Unfortunately, in some ways the gable top carton
lacks the structural integrity of other containers, especially
cans. For instance, gable top cartons are relatively
intolerant of internal vacuum or pressure. Also their
physical properties make them less tolerant of high
sterilization temperatures. As discussed below, these
drawbacks have inhibited use of gable top cartons in shelf
stable packaging.
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1336147
Typically, gable top cartons are formed of
paperboard sheet material having an overall coating of
thermoplastic film such as polyethylene applied on the
surfaces of the sheet. The plastic coated paperboard is
impervious to moisture and is particularly suitable for use in
packaging products such as milk and orange juice. The
thermoplastic coating not only serves to moisture proof the
carton but also can be utilized for sealing the carton closing
flaps which characterize the gable top carton. This sealing
action is accomplished by heating the surfaces to be sealed
while pressing them tightly together to form a liquid tight
plastic-to-plastic bond.
The carton erected from the plastic-coated blank
typically includes a bottom, four sidewalls extending from the
bottom and united along their lateral margins, and an upper
closure means which can be opened to form a spout. The
closure is formed from four end wall portions united with the
sidewalls and with each other at the lateral margins; the end
wall portions are inclined in pairs toward each other and have
marginal portions heat sealed to each other which form
extensions of the end wall portions; the marginal portions of
two
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~ ppocioe end wall portions ~!re folded like bellows between the
outer marginal portions of the two remainin~ end wall portions
and at least one of the two inwardly folded marginal portions-is
moveable outward together with the pertaining end wall portions
5 from its position between the two outer marginal portions to a
new position outside these where the marginal portion after
bein~8 moved outward, as well a5 its pertaining end wall
portion, form a ;pouring spout and an emptying passage.
Traditionally, dairy products and fruit juices packed
]0 in gable top cartons have been kept refrieerated throughout the
distribution process in order to avoid almost immediate spoilaQe.
This spoilage wol~ld result from the fact that the gable top
cartons are not sterilized and that bacteria in the environment
and on the inside of the carton itself would develop -very
15 quickly. It Is only refrigeration which retards spoilage for up
to a couple of weeks. Products packed in this way are not said
to be shelf stable.
Shelf stability i s extremely desirable from many
standpoints . A shelf stable product i s much less likely to spoil
20 while in the distribution system and with a shelf life measured
in months rather than days losses due to spoilage should be
low. The packer does not need to maintain the product under
refrigeration either in its warehouse or while in transport.
~imilarly the retailer need not allocate expensive refrigerated
25 space to store its supply of product. The consumer also has the
advantage of a product which does not require refrigeration
unt il opened .
Shelf stability may only be achieved in two ways.
First, use may be made of chemical preservatives.
30 Alternatively, precsutions must be taken to exclude the
possibility of bacteria coming into contact with the product
following pasteurization of the product itself.
In order to achieve shelf stability of 8 juice or
similar liquid food product without using chemical preservatives
~35 the product must be sterilized ~said to be pasteurized).
Followin~, pasteurtzation no bacteria must be permitted to come
into contact with the product. ~o ensure that this is the case,
all bacteria which may come into contact with the product prior
to or at the time of fillinQ and sealing oî the carton, all
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baCt.eL'ia Wit~ fle ca~lo~ ~nd all ~,dcteria in the environment
which becomes trapped in the carton after sealing must be
'killed. Failure to do so will inevttably lead to spoilage.
,
With' glass containers and cans a process known as
5 post packaging sterilization ha s been employed to achieve shelf
stability. The ~iquid is poured into a non-sterile container, the
container is capped and sealed; the container and its contents
are héated to an`d maintained at a sterilization temperature until
all the bacteria within the container are killed; the container is
10 then cooled; the product is then shelf stable.
This process ha s been used in the brewing and soft
drink trade in packaging liquids in bottles and cans. It has
also been used to package liquids in flexible containers. For
exarrple, U.S. patents 4,088,444 to Byrne and 2,995,418 to Muller
15 each disclose a sterilization process wherein a container formed
from flexible material such as plastic i5 filled with a liquid,
sealed, and sterilized by first subjecting the container to a hot
liquid bath or to steam until the temperature of the liquid in
the contsiners reaches the sterilization temperature, maintaining
20 the temperature at the sterilization temperature until
sterilization is effected, and thereafter cooling the liquid in the
containers by subjecting the containers to cold water. I~uller in
particular ,pecifically ccntemplates sterilizing fruit juices which
are in sealed plastic containers.
I,'.S. patent 4,376,126 to Evers discloses a method of
making a yogurt beverage which includes the steps of
pD steurization or sterilization after the beverage ha s been
packed in a container. Evers, however, does not appear to
specifically disclose the use of any particular container nor
30 does he mention the special problems associated with gable top
cartons,
U.S. patents 4,057,391 to Yamaguchi, 3,481,688 to
Craig et al. and 2,380,134 to Waters disclose methods of
preserving or sterilizing food in flexible containers, such as
35 plastic containers, whereby the food is sub~ected to heating and
then cooling after being sealed in the containers. However,
these patents do not specifically teach the sterilization of liquid
food products, such as fruit juices nor do they address the
special problems associated with gable top cartons.
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13b36147
U.S. patent 237,449 to Schaum erg et al. discloses a
rnethod of preserving fruit juices in glass boItles that includes
bottling and sealing the juices and thereafter heatin3 ohe ~uices
to 170F for 35 minutes . However, Scha umberg et al . does not
5 disclose subjecting the heated bottles to a coolin~ process and
does not contemplate the use of plastic or plsstic coated cartons
nor does he address the special problems of gable cartons.
Despite the wide recognition of the usefulness of most
package sterilization in other packaging systems, the process
lO has not to the inventor's knowledge previously been used to
package perishable liquids in gable top cartons.
Since the introduction in the 1950's of paper-based
cartons for liquid food products, only two processes have been
widely promoted in order to permit paper-based cartons to be
]S used for packagin~ shelf stable products. These are the aseptic
process, promoted since the early 1960' s by Tetra Pak of Sweden
principally in association with the so-called brick pack, and
the hot fill process more recently a dapted for gable top cartons
from a process used in connection with glass bottles.
In accordance with the aseptic process the product is
pasteurized and kept in a sterile environment up to and through
the filling and sealing of the container which is pre-sterilized
(generally using hydrogen peroxide and steam) and also kept in
- a sterlle environment until filling and sealing. The seal must
2S be hermetic under all conditions. Aseptically processed brick
packs must be cut, pierced or torn to open. In each case
either the opening or the re-closing is clumsy and is not
considered advantaQeous from a consumer convenience point of
view. The a septic method is complicated to carry out and
30 requires specialized and expensive equipment.
No`twithstanding the comp]exity and cost of the
aseptic process it became widely accepted in Europe, Australia
and Canada in the 1970's. It was only approved in the United
States in the early 1980's and has become widely accepted since
35 that time. Prior to the introduction of the aseptic process and
the brick pack there were no shelf stable products packaged in
paper-based contalners. The useptlcally packed brick pack
created a whole new application for paper-based containers.
The success of the aseptically packed brick pack has been
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nothing short of phenomenal. It is estimated that, on a
worldwide basis, asepttcally packed brick packs account for
over $20 bil]ion dollars worth of liquid food products.
Because of the complexity and cost of the aseptic
5 process, efforts were made to achieve shelf stability in
paper-based containers, most desirab]y with the popular gable
top carton, with simpler less expensive technology. In the
early 1980 s a so called hot fill process was proposed.
A less costly alternative to the aseptic method, the
10 hot fill method did not meet with~much success. In accordance
with the hot fill method the pa steurized product is heated to
temperatures in the range of lôS degrees ~ and poured hot
directly into the gable top carton which is then sealed. The
heat of the product itself kills the bacteria remaining within the
]5 container after sealing.
In the llnited States the hot fill method for gable
cartons was adopted by various juice packers but has largely
been abandoned because this method results in a substantial
vacuum being created within the container following the cooling
20 of the product from the hot fill temperature to room temperature.
This vacuum is undesirable because It promotes the inflow of
bacteria from the environment through the seal which leads to
quick spoi~age unless the product is refrigerated. In order to
deal with this problem the seal must be strong enough to
25 withstand the significant pressure differential created by the
rocess. The seal must also be strong enough to retain its
integrity in al~ cases throughout the distribution process. If at
any time seal integrity is lost, the vacuum will cause bacteria
to enter the carton and virtually immediate spoilage to occur.
Where the seal was made sufficiently strong to
prevent the entry of bacteria under all conditions, the cartons
were so hard to open that consumers, used to the ease of
opening of the weakly sealed gable cartons used for dairy
products, resisted the container.
In practice, the strength of the seal which had to be
provided to overcome the prob~ems created by th high vacuum
resulted in a significant percentage of the cartons not being
readily openable by the consumer in the ordinary way. This
was such a problem that International Paper, the principal
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proponent of the hot fill technology, deveioped an &l~ernative
form of opening the carton, subject of l~S patent No. 4,527,732
issued in 1985, which covers a scored "smile" to be pushe,d
throuQh by the consumer.
Thus up until the present invention industry efforts
to adapt the popular gable top carton to achieve shelf stability
and yet retain ~its good opening and handling qualities all at
reasonable cost have heretofore not proven successful; and this
despite the fact that finding sn uncomplicated and inexpensive
10 method of achieving shelf stability with a gable top carton
would open up a market worth at. least several hundred million
dollars for cartons alone.
Thus, there remains a need for a system for shelf
stable packagtng of perishable liquids which allows use of a
15 gable top carton which can be hermetically sealed to ensure
shelf stability while retaining an easily opened spout necessary
for consumer acceptance.
SU~ iARY OF THE INVENTION
The present invention overcomes the difficulties
referred to sbove in adapting the gable top carton for the
20 packaging of shelf stable liquid producis such as juices in a
manner acceptable to the consumer. The present Invention is, to
some extent, the consequence of the present inventor's
recognition of a significant interrelationship between the
strength of seal necessary to maintain hermeticity and the
25 process used to sterilize the gable top carton.
Having recognized this, the present inventor has
determined that the lack of commercially viable system for shelf
stable packaging in gable top cartons is primarily due to a
failure to find an acceptable compromise between hermetically
30 sealing and ease of opening of the sealed spout of the S~able top
carton. These two objectives are diametrically opposed; the
stronger the seal, the harder it is to open and the lesser the
consumer acceptance.
The present inventor has discovered that shelf
35 stability wlth an easy to open gable top carton can be achieved
through the selection of an appropriate post-pa sturization
process combined with an appropriate seal design. The inventor
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CA 1336147 - 9 -i
has also di5covered that an adequate seal which is still easy to
open can be achieved by applying increased pressure at certain
empirically lo~cated critical points along the seal. If these
critical points are adequately sealed, the remainder of the seal
5 can be sesled in an easy open fashion. Consequently, the spout
is still easy to open.
- ~ In summary, the inventor has discovered a technique
for achieving the shelf stable packaging of perishable liquids in
a gable top carton which is easy to open. The technique
10 involves the combination of a technique for sealing a liquid in
a gable top carton and a process for sterilizing the interior and
contents of the sealed carton.
In accordance with the present invention, the liquid
food product to be packed is first pasteurized, if required, in
15 accordance with procedures appropriate to particular product.
The product is then cooled to room temperature and introduced
into gable top cartons which are then satisfactorily hermetically
sealed at the ernpirlcally determined critical points slong the
sealing portion of the gable top carton in accordance with the
20 method described below in such a wa y as to permit their ea se of
opening for the consumer. The filling process is open to the
environment.
The sealed cartons are then heated to and held for
an appropriate time at a post-pasteurization temperature
25 appropriate to kill the environmental bscteria, mold and yeast
remaining within the product and within the carton but at a
temperature below that which would melt the inner plastic layer
of the carton or cause delamination of the carton. Generally a
post-pa steurization temperature in the range of Dbout 160F is
3 appropriate with a preferred temperature of about 167F with a
holding time of about 10 minutes. The cartons are then cooled.
Because the contents were originally sealed in the carton at
room temperature and returns to room temperature after being
heated, no vacuum is created (i.e. no pressure differential
35 across the seal) and thus there is no dan8er that environmental
bacteris will be drawn into the carton in the event the integrity
of the seal is s~bsequently lost. While the seal is hermetic, it
need not be as stron~ as that required if the hot fill process
were used and is therefore more acceptable to the consumer
because the carton remains easy to open.
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1336147
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Thus in accordance with one aspect of the invention
there is provided a method of shelf stable packaging a
perishable liquid food product in a gable top carton which is
internally coated with thermoplastic and which includes
sealing flaps which comprise side flaps and inwardly folded
end flaps, the lower edge of each of said flaps being defined
by a horizontal fold line where the flaps splay to form the
top of the carton, each of the flaps having an upper edge, the
upper edge of the side flaps extending beyond the upper edges
of the end flaps, one set of which end flaps being outwardly
foldable to form a spout, the method comprising the steps of:
a) ensuring that the liquid food product is free from
pathogenic and thermophilic organisms; b) filling the carton
with the liquid food product maintained at substantially room
temperature; c) hermetically sealing the carton by applying
heat and a predetermined amount of pressure to predetermined
portions of the sealing flaps and applying less pressure to
other portions of the sealing flaps so as to produce an easily
opened seal; d) heating the food product in the sealed carton
to a temperature sufficient for pasteurization but below the
softening temperature of the thermoplastic coating;
e)maintaining the food product at the pasteurization
temperature for sufficient time to kill essentially all
microorganisms remaining within the carton; and f) cooling the
gable top carton and its contents.
1336147
-9b-
In accordance with another aspect of the invention
there is provided a sealed gable top carton and a perishable
liquid food product contained therein, the gable top carton
having a gable closure which includes opposed side panels with
side flaps extending therefrom and opposed end panels with end
flaps extending therefrom to a lower height than the height of
the flaps of the side panels, both said side flaps and said
end flaps each having upper portions and lower portions, said
side panels and end panels having fold lines to facilitate
closing and opening, the opposed side flaps being adhered to
each other and the end flaps being adhered to the lower
portions of the side flaps, the carton being sealed by
applying varied pressure across the flaps so that different
regions of the flaps are sealed with different amounts of
pressure to provide a strongly sealed area and a first lightly
sealed area at the center of and at the upper portion of an
end flap to facilitate opening of the carton by a consumer;
the perishable liquid food product being filled into the
carton at about room temperature before the carton is sealed,
heated to a pasteurization hold temperature after sealing and
maintained at the pasteurization hold temperature for a time
sufficient to pasteurize the product and sterilize the
interior of the carton.
133~147
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In accordance with still another aspect of the
invention there is provided a shelf stable system for storing
perishable liquid product comprising: a thermop'astic coated
gable top carton, the carton having a gable top closure which
includes closure sealing flaps which can be sealed to one
another by applying heat and pressure to the flaps; and, a
perishable liquid food product; wherein the product is cold
filled into the carton before the carton is sealed and the
carton is then sealed by applying different amount of pressure
to different regions of the flaps so as to provide a hermetic
easy to open seal; and, wherein the sealed carton and
perishable product are then heated to a pasteurization hold
temperature, maintained at a pasteurization hold temperature
for a time sufficient to kill essentially all microorganisms
remaining in the carton and then cooled such that the product
is shelf stable within the sealed carton.
In a still another aspect of the invention there is
provided a sealed top carton and a perishable product
contained therein; the gable top carton comprising a bottom
panel, opposed side panels and opposed end panels and a gable
top, the gable top being formed by folding and sealing the
side and end panels to one another, the table top carton
having a thermoplastic surface layer which softens at a
predetermined temperature, the gable top carton including a
top sealing portion for sealing the interior of the carton,
the top portion having a plurality of regions, each region
being sealed with a different amount of pressure so as to
: provide a hermetic seal which is easy to open;
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13361~7
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the product being cold filled into the carton before sealing
of the carton and the product being heated and main'~ained at a
pasteurization hold temperature after the carton is sealed,
the pasteurization temperature being sufficient to kill
essentially all microorganisms remaining in the c~rton but
below the predetermined temperature at which the carton's
surface layer softens; the carton being sufficiently sealed to
ensure that the product is shelf stable.
In yet another aspect of the invention there is
provided a process for packaging a perishable liquid product
free from pathogenic and thermophilic organisms in a shelf
stable gable top carton which has a temperature surface layer
which softens at a predetermined temperature and includes
opposed side panels with side flaps extending therefrom to a
lower height than the flaps of the end panels, the process
comprising the steps of: a) cold filling the gable top carton
with the product; b) sealing the carton by applying heat and
pressure and to oppose side flaps to soften the thermoplastic
layer so that the opposed flaps adhere to each other and the
end flaps adhere to the lower portions of the side flaps and
applying less pressure to an area at the center of the upper
portion of an end flap to form a lightly sealed area which
facilitates opening of the carton by a consumer; c) heating
the product in the sealed carton to a pasteurization hold
` temperature which is above the pasteurization temperature of
the product but below the softening temperature of the gable
top, carton surface layer material; d) maintaining the food
product at the pasteurization hold temperature for sufficient
time to provide an adequate kill of microorganisms in the
carton; and e) cooling the product within the carton.
1336147
- 9e -
In a still further aspect of the inventi~n there is
provided a shelf stable package comprising a gable top carton
containing a food product, the carton having a surface layer
which softens at a predetermined temperature and including
opposed side panels with side flaps extending therefrom and
opposed end panels with end flaps extending therefrom to a
lower height than the flaps of the side panels, said side
flaps having lower portions and said end flaps having upper
portions, the package being made by a process comprising the
steps of: a) cold filling the gable top carton with the
product; b) hermetically sealing the carton by applying heat
and a first amount of pressure to predetermined critical areas
of the opposed side flaps to soften the surface layer such
that these critical areas adhere to each other and the end
flaps adhere to the lower portions of the side flaps and
applying a second amount of pressure, which is less than the
first amount of pressure, to other, non-critical, areas of the
flaps so as to leave areas which are lightly sealed at the
center of the upper portions of the end flaps to facilitate
opening of the carton by a consumer; c) heating the product in
the sealed carton to a pasteurization hold temperature equal
to or greater than the pasteurization temperature of the
product but below the softening temperature of the gable top
carton material; d) maintaining the food product at the
pasteurization hold temperature for sufficient time to provide
an adequate kill of microorganisms in the food product; and e)
cooling the product within the carton.
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The present invention offers significant advantages over the hot
fill method. With the present invention the desirable easy
opening characteristics of the gable top carton may be retaine,d
which is not possible with the hot fill method because the seal
5 must be very strong in order to overcome the pressure
differential across the seal created by thst process. In the
event that seal integrity is lost or a leak occurs in a container
packed by the hot fill method, the internal vacuum will
immedistèly draw harmful microorganisms into the container
10 which will lead to spoilage. With the present invention,
because there is no vacuum in the head space above the liquid
in the carton, a minor break in t,he seal or leak elsewhere will
not result in microorganisms being drawn into the carton and
th u s spoila ge will be avoi ded .
~5 As compared with the aseptic process, the present invention
requires much less sophisticated equipment which is both less
costly and easier to operate. It is estimated that, taking into
account capital costs and operating costs, the present invention
can be worked for approximately 50% of the cost of the sseptic
20 process ln operations of a certain size. The present invention
is also more secure than the aseptic process. Packing in the
asertic process must be done in an entirely aseptic environment.
If, because of equipment or operator problems, any bacteria
should find its way into the product or the container after they
25 have been separately sterilized and before the package is
sealed, then spoila~e will occur. The present invention permits
the filling to be done in an open environment because the
bacteris is killed after the package is sealed ~nd no further
opportunity for bacteria to enter the carton occurs.
30 Another advant~ge of the present invention over the aseptic
process is that the present invention does not require a
sterilizing agent such as hydrogen peroxide. With the aseptic
`~ process it is slways possible that traces of hydrogen peroxide
re~ain on the inside surfsce of the container and contaminate
35 the product. The use of hydrogen peroxlde also presents a
problem for workers packing the product. If for any reason the
ventilation system required to evacuate hydrogen peroxide
vapours Eihould not operate properly, the atmosphcre in the
packing area may very quickly become contaminated and pose a
health hazard to the workers. The present invention presents
no such danger.
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BRIEF DESCRIPTION OF THE DRAWINGS 1336147
FIG. l is a perspective view Or a conventional gabletop carton having an arrangement in a closed state
FIG. 2 is a perspective view of the package of
FIG. I in an open state;
FIG. 3 shows part of a blank for making a gable top
carton;
FIG. 4 is a perspect~ve view of a gable top carton
according to the present invention;
FIG. 5 shows the carton of FIG. 4 partially opened;
FIG. 6 shows the carton of FIGS 4 and 5 opened up
to show the heat sealed areas.
FIG. 7 is a view of a die used to seal the carton of
FIGS. 4 and 5.
FIG. 8 is a perspective view of a ~ gable top carton
in accordance with another embodiment of this invention
illustrating the opening of the carton;
FIG. 9 is a perspective side elevation view of the
female portion Or a die for producing the embodiment of FIG. 8;
and
FIG. 10 is a perspective side elevation view of the
male portion of a dic for producing the embodiment of FIG. 8.
`~ FIG. ll is a perspective view of an improved male
jaw for sealing a gable top carton;
FIG. 12 is a perspective view of an improved female
25 jaw for sealing a gable top carton;
FIG. 13 is a cut-away view Or a gable top carton;
FIG. 14 is a side view Or the top of a gable top
carton .
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DETAILED DESCRIPTION OF THE INVENTION 133~147
FI~S. 1-3 show a conventional gable top carton cons-
truction .
The package shown in the drawings has four
sidewalls I and a bottom (not shown). Furthermore, the
5 package`has fou~ end wall portions 2 which are united on one
hand with the sidewalls I and on the other with each other. At
the upper free margin, the end wall portions 2 are provided
with marginal portions 3 and 4 which are folded toward each
other in such a way that opposite end wall portions 2 are
10 inclined in pairs toward each other and that the marginal
portions 3 of two opposite end wall portions lie folded like
bellows between the marginal portions 4 of the two remaining
end wall portions. Thus, the end wall portions 2 which are
provided with the inwardly folded marginal portions 3, will, as
15 shown in FIG. 3, be divided into three essentially triangular
portions, the intermediate one 5 of which extends between the
end wall portions 2 provided with the outer marginal portions 4,
while the two side portions 6 rest against the inside of each of
each one of these.
The gable top carton is constructed from sheets of
material which include at least a basic outer layer of cardboard
and an inner layer of thermoplastic material. Normally, the
sheet is entirely plastic coated and can include additior;al
barrier layers. The preferred structural material of the present
invention is in five layers, namely, an inner coating of
polyethylene and alumLnum (or other satisfactory barrier
material) barrier, another polymeric layer to bond the foil, a
; layer of pa'per board and an outer layer of polyethylene or
lacquer. A sixth layer, usual for hot filling methods, is not
needed with the present invention. Suitable plastics for the
carton also include vinyl resins, such as polyvinyl chloride,
regenerated cellulose, polypropylene, polyethylene terephalate,
polycarbonates and other plastics that are used for food
products. Where a barrier layer is to be used, ethyl vinyl
alcohol or like barrier film may be substituted for foil. The
sealing Or the package with the marginal and end wall portions
in the position shown and described is brought about by means
of heat, which will fuse the thermoplastic layers with the
sealing zone.
-:, ,,,~
r ~ 3 3 ~ ~ 4 7 ~ 3
When the package is to be opened, the seal is torn
open over one half of the sealing zone, whereupon the inwardly
folded marginal portion loeated in said zone i5 pulled out to the
position shown in FIG. 2, where the marginal and the end wall
5 portions will form a pouring spout.
FIG. 3 shows part of a blank for a package of the
indicated kind. The drawing shows essentially only that part
of the blank wl~ich i5 to form the inside surface of the marginal
and end wall portion of the package, which can be opened.
10 The blank is provided with fold or score lines along which the
blank is to be folded as to form the finishéd package.
Referring now to FIGS. ~ and 6, the carton
illustrated is mainly of conventional construction. It includes
opposed pairs of side walls 10 and 11, connected by a fifth
15 panel 12. There is a bo~tom closure 13 and a gable top
generally indicated at 14. The gable top includes a pair of
side panels 15 having fold or score lines 16 to facilitate
opening and a pair of end panels 17 having fold or score lines
18. A pair Or top or side flaps 19 are extensions of side
20 panels 15 and extend somewhat higher than end flaps 20 that
are an extension of end panels 17. Side flaps 19 are heat
sealed in face to face relationship as shown. Flaps 19 and 20
splay at horizontal fold line 27 to form the top of the carton.
End flaps 20 are heat sealed to the interior of the lower parts
25 of side flaps 19 as shown in FIG. 5.
Both in the case of hot fill and for non-shelf stable
packed juices and dairy products flaps l9 and 20 are sealed
over their entire surfaces. It is also known to provide further
` additional optional sealing such a s a pair of vertical stake
30 lines 21 at the end that is not to be opened and which coincides
with the fifth panel 12. Optionally, at the other end there is
stake line 21a. There may also be a horizontal stake line 22
extending across the side flaps 19. Stake lines are strongly
indented to give a more secure seal. There may also be a
35 center stake point 7O which presses toeether, expands into
abutment and seals the adjacent edges of the inwardly folded
end flaps 20. The foregoing is conventional structure.
The present 1nventor has discovered that, in
combination with an appropriate post-pasturization process, the
said optional sealing areas are the truly eritical ones. If
.,.
r:
~33~47
- 14 -
these are made then it is not necessary to seal flaps 19 and
20 uniformly over their entire surfaces. Having realized this
the present inventor empirically discovered what specific
areas other than the critical areas should be sealed and the
extent of such seal in order to achieve the desired easy
opening characteristic in a shelf stable gable top carton.
Since sealing at the critical areas is sufficient to
ensure that, in combination with the post-pasteurization
process selected, the seal will in a commercially acceptable
percentage of cases keep bacteria out of the carton, the non-
critical areas, i.e., the areas which are not staked, can be
selectively sealed lightly or not at all to make the carton
easy to open. One such construction is shown in FIGS. 4-6.
The difference from conventional structure according
to this embodiment is in the area of the seal between side
flap 19 and end flap 20. According to conventional practice
in the case of hot fill, the whole of the interior of end
flaps 20 are sealed to side flaps 19. According to this
invention an area which may be in the shape of an inverted
`~ triangle or a notch or a sector is left unsealed or lightly
`~ sealed at the top center of end flap 20 as indicated by the
numeral 25 in the broken away part of FIG. 5. The r- ~;ning
sealed area is stippled and indicated at 24. In FIG. 6 the
unsealed or lightly sealed area is shown at 23a and 23b which
combine to provide area 23 when the carton is closed. It has
been found that particularly when the stake point 70 is
located at the apex of triangle 25, an effective seal is
provided in spite of this unsealed or lightly sealed area.
- 14a - 1336147
The unsealed area at the top center enables the consumer to
start opening the carton and also results in there being less
seal to pull apart where the consumer has the least leverage.
FIG. 7 illustrates the male jaw of a suitable die 30
including die face portion 31 for pressing together the upper
part of side flaps l9k, die face portions 32 and 33 for the
ends and horizontal stake embossing line 34, vertical stake
embossing lines 35 and embossing protrusion 36 for the
vertical stake point. Die face portion 37 which presses flaps
19 and 20 together is cut away at 38 to leave a triangular
unsealed or lightly sealed area. This can be used with a
matching female die.
1~
Alternatives for providing the desired unsealed area
would include the use of silicone as a parting agent or
, "abhesive" to prevent adhesion in area 25. Another possibility
if adhesives were used in place of specifically m'ade heat r ~ ~
sealing jaws would be to omit adhesive in area 25. These ~ 6 1 ~1
methods are generally more expensive and less reliable because
of the risk of misalignment of the parting agent to the desired
non-adhering, srea. Thus, heat sealing with specially patterned
jaws is the pref,erred method of closure where, as usual, the
carton is coated internally with a thermoplastic resin.
FIG. 8 illustrates an improved structure which is
similar to that illustrated in FI~GS. 4 to 6 but showing an
unsealed or lightly sealed area at the top of flap 20
immediately above stake point 70 substantially in the shape of a
]5 rectanQle 25a instead of the tri~ngle of FIG. 5 and showing a
further unsealed or lightly sealed area 25b extending between
stake point 70 and vertical stake line 21a. Aress 25a and 25b
are left unsealed or are lightly sealed by providing a die which
applies no pressure or little pressure in these areas.
The construction of a suitable die is illustrated in
FIG. 9 showing female jaw 41 and FIG. 10 showing male jaw 40.
Referring now to FlG. 10, male jaw 40 has a die face 42 having
a raised longitudinal rib 43 to provide a horizontal stake line
and vertical ribs 44 and 45 to provide vertical stake lines on
the side of the container that i s to remain sealed and a vertical
rib 46 to provide a vertical stake line on the spout end of the
carton (i.e. the end that is to be opened). Male jaw 40 has a
set screw 47 to provide a central stake point 70. The generally
rectangular relieved, area 25a of FIG. 8 is provided by
depressed area 48 immediately above set screw 47 and offset in
the directio,n of the side of the carton that is to be opened. A
relieved area 49 is also provided extendin~3 from set screw 47,
which provides center stake point 70, to rib 46 which provides
vertical stake line 21a. Male jaw 40 also includes area 50 for
sealing side flaps 19 of the carton and areas 51, 52, 53 and 54
for sealing the remainder of end flaps 20.
Female die 41 shown in FIG. 9 has an upper area 55
which mates with portion 50 or the male jaw and a slightly
undercut area Sl the upper edge Or which is located to
accomodate rib 43. Die 41 has slots 56 and 57 to accomodate
ribs 44 and 45 and slot 58 to accomodate rib 46. lt also has a
~, ., . _ ,
r -- ~6 -- i3 3 6 ~ ~7
depressed area 59, to relieve pressure, matching area 49 of the
male die ~nd generally rectangular pressure relieving area 60
matching area 48 of the msle die.
FlGS. 11 and 12 show an even further improvement of
5 the male and fem~le ~aws respectively. The jaw construction
shown thereln is similar to that shown in FIGS. 9 and 10 where
similar reference~ numerals are used. However, there are several
differences which have been cmpirically found to yield better
results. The differences reside in the region below the
longitudin~l rib 43 and between rib 45 ~nd rib 46. It should
be noted that in all of FlGS. 9-12, the depth of the depressions
relative to one another is exaggerated for emphasis. In FIG.
11, the set screw 47 used to define the stake point in the ~aws
shown in FlG. 10 is replaced with a protrusion 471 which may
be of semi-circular shape as shown. The protrusion 471 is in
fact recessed from the longitudinal rib 43 but extends out
generally as far as the ribs 44, 45 and 46. The male ~aw also
includes a recessed portion 53 like that of male ~aw shown in
FlG. 10, but the recessed portion 53 includes an inclined recess
portion 494 recessed at an an~le of about 30to 40 with one
edge contacting the recessed surface 53 and one edge extending
significantly below that surface. Another surface 492 is
recessed from the recess surface 53 and,optionally, a further
recessed portion 691 is recessed from th~ portion 492.
The female jaws shown in FIG. 12 are similar to the
female ~aws shown in ~IG. 8 with the exception of modification
made in the depressed area 59. Specifically, in the modified
jaw, the depressed area 59 is significantly depressed. From
this depressed area are provided a number of areas which are
less depressed, i.e., protrude from the depressed area 59.
These include the areas 60 and 58 and a protruding area 472
which ts adapted as a stake plate for protrusion 471 in the
male jaw to provide a heavtly staked area.
A protrusion such as 36, 47 or 471 is necessary to
create a center stake which will block the natural path bacteria
might follow to enter the carton. This path would be from the
edge of the carton along a channel 28 just above the upper
edges 20a of end flaps 20 as shown in FIGS. 13 and 14 and
down into the carton between the folding points of end flaps 20
where a natural gap 29 occurs. Accepted practice dictates that
the larger the center stake in the gap region 29 the better.
. . .,, w ,
'
1336~47 l
- 17 -
The present inventor has discovered that to ensure
the easy open characteristic desired the center stake should
be optimally placed below and as close to the upper edge of
the end flaps as possible with a shape and area sufficient to
adequately close the gap 29 and no more such as shown at 71 in
FIG. 14. The present inventor has further discovered that if
this is done and area 26, being the intersection of the fold
or score lines on panel 17, is left substantially unaffected
by the center stake, this area will "pop" out during the
opening process and greatly facilitate the opening of the
carton. It is believed that this arrangement allows sub-
panels 17a and 17b to toggle effectively without distortion
and thus bring greater force to bear in breaking the seal.
Although the location and dimensions of the stake
areas and the corresponding design of the jaws have been
derived empirically, it has been found that generally the
critical areas are those areas necessary to ensure a minimum
complete seal of the flaps. Further, it has been found that,
by relieving sealing pressure immediately adjacent to critical
areas, improved sealing is achieved. Specifically, when the
areas immediately adjacent the critical areas are relieved the
force applied by the jaws to seal the flaps occurs at t
reduced area, i.e., only at the critical areas. Accordingly,
when a constant amount of pressure is applied to the jaw, the
provision of a recessed area decreases the area of contact
upon which high pressure is applied and thus increases the
sealing pres~ure per unit of area o~er the critical areas; as
a result, a stronger seal without an increase in pressure
applied to the jaws.
.. .
' -
1336147
- 17a -
Traditionally, gable top cartons were heat sealed
evenly across the flaps by flat non-patterned planar jaws.
The practice then developed to further strengthen the seal by
adding horizontal and vertical stakes and a center stake. It
is believed that until the present invention, it was not
understood that, so long as a process could be developed which
would not create any significant pressure differential across
the seal, a practical seal could be achieved by relying
principally on the sealing effect of the horizontal, vertical
and center stakes. With this realization it became possible
to relieve sealing pressure, and thus the bond strength
between the flaps forming the seal, over those other areas
which would significantly improve the opening characteristics
of the carton.
~ - 18- ~3361~7
The ` sesling of the gable top carton can be
accomplished by employing the techniques described above so as
to ensure ~ strong seal at certain critical areas while
maintaining an essy to open carton. To ensure that this seal
5 is adequate to ensure shelf stability, however, the contents must
be sterilized or pasteurlzed in such a way that a stronger seal
is not requlred snd sdditional forces are not spplied to the
seal. As noted above, this means that the so-called hot fill
method of pasteurization is not acceptable because it results in
10 a vacuum which reo,uires a stronger seal.
The present inventor has discovered that by
combining the sealing technique described above with the
following post-pack~ging pasturizatlon process, traditional gable
top cartons c~n be used to package shelf stable llquid products
15 and simultsneously retain their easy openlng characteristic
required in order to achieve consumer accepta nce .
It is believed that no such practical process has
previously been developed for post-packaging pasteurization in
easy to open gable top cartons constructed of plsstlc or
20 paperboard coated with plastic.
ln accordance with one aspect of this invention, the
method of providing liquid food products that are shelf stable in
easy to open gable top cartons comprises the steps of:
~ a ) cold filling a plastic coated gable top carton
25 with an essentially non-carbonated liquid food product free from
pathogenic Pnd thermophillc orgsnisms;
(b) sealing the carton as described sbove;
(c) heating the food product in the carton to a
pa steurization hold temperature in the range of ~bout 160 F
30 and preferably 167 F but below the softening temperature of the
plastic;
(d) malnt3inlng the food product st the
pssteuri2stion hold temperature for sufficient time to provide an
adequate kill of the bscteria remaining within the carton;
35 and
(e ) cooling .
The food products to which this invention is
applicable ~re those which are generally pourable and could be
advantageously packaged in gable top cartons, includinQ, for
.. ... ., . ;,
b
-~ - 19 1336147
example, liquid dairy products, non-carbonated fruit products
such as the citrus products or citrus flavored products, fruit
products, vegetsbles ~uices and vegetable cocktails. Carbonation
must be avoided as otherwise the pressures that would be
generated in the carton during the process would be too high.
S Another requirement of the food product is freedom
from pathogenic and thermophilic bacteria. Most juices and
drinks have pH's in the range 2.8 - 4.0 and not above pH 4.6.
At a pH above 4.6 there is a potential problem of pathogenic
bacteria. Below pH 4.6 the pr~blems are yeast, molds and
10 bacteria.
If the pH is above 4.6, which would include such
products as milk, then there should be a preliminary ultra high
temperature treatment ot 240F to 260F for 15-20 seconds to kill
patho~enic organisms, followed by cooling to ambient
15 temperature. A preliminary ultra high temperature treatment is
advisable with some vegetable base products such as tomato, due
to their initial high content of thermophilic molds.
The ~uices and drinks to which this process is
a?plicable are formulated in a tank at ambient temperatures in
20 the rsnge 40 - 75F and pretreated as discussed above if
necessary. They are then pu nped to a fillin'g station where the
juice or drink is fed into cartons.
Although not essential, it may be useful to provide a
sparging infusion valve in the line berween the tank and filling
25 station. The sparging infusion valve is used to add up to
about 0.1 Ips/square inch of nitrogen or carbon dioxide, and
preferably about 0.01 Ibs/square inch. The purpose of sparging
is to create a slight positive pressure to oppose the entrance of
sny bacteris into the carton after filling. Carbon dioxide is
30 preferred for this purpose. The product sparged with carbon
dioxide would have such a small amount of carbon dioxide that
it would not be classified as a carbonated product.
At the filling station which is of conventional type,
a number of individual cartons are filled cold. The temperature
35 of the liquid food product should be less than 80F and
desirably less than 70F to achieve a neutral or positive
pressure after filling. This may be contrasted with hot fill
temperatures of the order of 180F. The maximum temperature
. .
- that can oe used depends on the conditions including the
positive pressure from any spar3ing gas and on the strength of
the ~eal. After filling and closing the cartons there should b,e
a neutral to slightly posltive pressure. As previously indicated
5 a vacuum is undcsirable.
The cold filled cartons are transferred to a processor
comprising three zones, a preheat zone, a hold zone, snd a cool ( A ~ ~ 3 ~ 1 4zone .
The processor may be in the form of a continuously
lO moving chain upon which rows of cartons are placed. The
cartons are spaced to allow water to run down the sides of the
cartons to heat or cool the contents. Heating may also be
achieved in other ways such as the use of microwave energy
provlded no metal is used in the cMrton structure.
1. Preheat zone
15 - The cold filled cartons are preheated preferobly by
pouring water at a temperature of 180F - 185F onto the cartons
and allowlng it to coscade down the sides. After a period of
time that varies with the size of the carton. viscosity, solids
content, etc., the liquid product within it reaches the desired
20 "pa steurization hold" temperature . The ?referred temperature for
"pasteurization hold" is about 167F, which will be reached in
about 13-19 minutes in the case of 1 liter cartons. Two liter
cartons would take 20 to 24 minutes to resch this temperature,
while 4 to 7 minutes would be adequate for 250 ml. cartons. If
2~ microwave energy were used to heat the product, the time to
reach the pasteurization temperature may be different.
2. Hold zone
The product is maintained at the required
pasteurization temperature for e predetermined time to ensure '-
adequate kill of all microorganisms. The appropriate time at
30 various "pasteurization hold" temperatures is available from
sta ndard texts . At the preferred temperature of 167F a hold
time of ten minutes is recommended. The temperature should not
be greater than about 174F, at whlch the time will be about 4
minutes, as otherwise there may be problems with softening of
35 the plastic where the carton is polyethylene and delamination of
fo~l from paperboard will occur. Slightly higher temperature
.. ,,_ ~ ... ,~.
~ t
1336147
- 21 -
may be used with plastics having a higher softening point such
as polypropylene. At lower temperatures the hold time is
quite long. Fore example, at 160F it would be about 25
minutes.
3. Cool zone
After holding for the required amount of time, the
cartons go into a cooling zone which, if water chilled, may
exit at around 90F to 105F. This temperature is desirable
as it will quickly evaporate off any excess moisture adhering
to the carton.
The temperature of the cooling water may be about
35F to 60F. The cartons then leave the processor and are
packed in cases.
The process is further illustrated by the following
examples:
Exam~le 1
This example relates to the production of 1000
Imperial gal. of single strength (ready to drink) orange
juice. 135 gal. of orange juice concentrate 65 Brie (%
soluble solids) is added to 865 gal. of water and blended for
10 minutes. It is then pumped using positive pumps through a
line leading to a filler. The line includes a sparging
infusion valve to sparge carbon dioxide to give an end product
with about 0.1 lbs/square inch of gas. At the filler the
carton is filled at a temperature of about 70F into one liter
gable top cartons which are heat sealed in accordance with the
sealing technique described above. The cartons are brought up
to a temperature of 167F in 14 minutes and held at that
temperature for 10 minutes.
-
1336147
- 21a -
They are then chilled with water at 40F for 12 minutes to
give an exit temperature of 90F. The orange juice has a
desirable shelf life of three months and a recommended maximum
of six months. The taste of the orange juice is markedly
better than that produced by hot filling.
ExamPle 2
10 This example relates to a tomato and claim juice
cocktail. A thousand imp. gal. batch was made of water and
100 imp. gal. of tomato paste (32-34 Brix) 650 lbs of salt; 60
lbs
~~ - 22 - 133 6147
of monosodium glutamate; 700 Ibs of glucose solids; 30 lbs of
spices and 10 gal. of clam broth. It is pumped to a
pa steurizer where the product is brought to a temperature of
250F in about 10-20 seconds, and held at this temperature to 48
5 to 52 seconds, cooled at 70F and then filled and processed as
described in Example 1.
Example 3
This example relates to the packaging of milk in a
shelf stable easy to open gable top carton. The milk is first
pa steurized at a conventional UHT temperature such as 250 F
10 for approximately 8 seconds then immediately cooled to ambient
temperature. The milk is then cold filled into gable top cartons
in the normal manner under stringent sanitary conditions and
then sealed and processed as described in Example 1.
