Note: Descriptions are shown in the official language in which they were submitted.
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BEVERAGE CONTAINER
Field of the Invention
This invention relates to a beverage container for a
carbonated beverage which enables a close-knit creamy head
to be formed on the beverage as it is dispensed so that it
has an appearance similar to that of a beverage dispensed
from draught.
Background to the Invention
Such an appearance can be achieved by causing shear of
the beverage. This encourages the liberation of small
bubbles from the beverage and these gradually separate out
to form the close-knit creamy head. It is well known that
shear of the beverage can be caused by jetting fluid into
the beverage in the container.
Various methods have been disclosed for jetting fluid
into a beverage in a container upon opening of the
container to cause shear of the beverage. GB-A-1,266,351
discloses a container which includes an :s.riner secondary
chamber which is pre-pressurised with gas. The chamber is
initially sealed with a soluble plug which dissolves
shortly after filling the container with beverage, when the
pressure in the container is similar to that in the
secondary chamber. A small orifice is included in the
secondary chamber, and fluid is jetted from the secondary
chamber via the orifice into the main body of the container
causing the liberation of the required small bubbles in the
beverage.
GB-A-2,183,592 discloses a container including a
separate hollow insert having an orifice in its side wall.
As the container is filled, beverage is introduced into the
hollow insert through the orifice. Upon opening the
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container, beverage from the insert is jetted through the
orifice into the beverage in the container again causing
shear of the beverage.
WO-A-91/07326 discloses a system in which an insert
which jets gas only into the beverage in the main body of
the container is pre-pressurized with gas and includes
closure means. The closure means remains sealed before
filling and during the container filling operation but when
the beverage container is subsequently opened,
de-pressurization of the beverage container results in the
insert releasing a surge of gas from a restricted orifice
into the beverage to "seed" the required nucleation of
dissolved gas bubbles to produce the required rich creamy
foam. Since the insert is sealed at all material times
before the container is finally opened by the consumer the
container and insert combination can be filled as easily,
simply and quickly as conventional container. Examples of
the closure means includes a burst disc and a pressure
responsive valve. A disadvantage of this type of system is
that the insert may contain a residual pressure after the
container has been emptied. There is a risk a consumer
will cut open the empty container and thus be able to
interfere with a pressurised insert.
WO-A-91/07326 discloses a very large number of ways in
which the pressurized gas insert can be formed and mounted
within the beverage container. In most examples, the
insert is mounted so that, in use, it is located at a
fixed position. However, an example is also described
where the insert floats in the liquid in the container.
A problem which occurs with fixed inserts results from
the way in which a container is handled during opening.
When opening a bottle with a crown cork type closure the
bottle is often tipped almost horizontally if opened using
a fixed opener. Equally when opening an easy open feature,
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either a ring pull or a stay-on-tab on a can it is common
to tilt the can on opening. In both cases, immediately
after opening the closure the container is then tipped to
dispense its contents. These actions can result in the
restricted orifice of the insert not being immersed in the
beverage whilst gas is being jetted from it. In such a
case the insert does not function correctly.
GB-A-2280887 discloses a carbonated beverage container
including a floating hollow insert having a first duckbill
valve arranged to allow gas to enter the insert, and a
second duckbill valve arranged to allow gas to be jetted
from the insert. The insert is arranged to float on the
beverage wil-.:i the first valve in a headspace above the
beverage, and with the second valve below the surface of
the beverage.
The insert of GB-A-2280887 does not have to be pre-
pressurized. As the insert floats on the beverage, the
insert may be dropped into the container before or after
filling, and therefore the assembly of the container and
insert is much simpler than for containers in which the
insert is fixed in the container. As the insert floats,
the problems of orientation, including gas not being jetted
into the beverage, and beverage entering the insert, which
are associated with fixed inserts, are overcome. Further,
the nature of the containers is not critical since it is
not necessary to form an interference fit with them, or
adapt them specifically to hold the insert at a particular
location.
The use of duckbill valves through which fluid is
jetted in the insert of GB-A-2280887 is particularly
beneficial. The size of the aperture through which the
fluid is jetted varies with the pressure difference across
the valve and the nature of the fluid being jetted. This
variation in the size of the aperture ensures the fluid
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jetting into the beverage causes optimum shear. This
allows the volume of fluid required for jetting into the
beverage to be reduced when compared to the volume required
when jetting through a fixed size orifice.
The insert of GB-A-2280887 may be moulded from a
plastics material such as polypropylene, or be formed of
metal such as lacquered aluminium, lacquered tin plate,
polymer coated aluminium, polymer coated tin plate or tin
free steel. The duckbill valves are manufactured from a
thermoplastic elastomer (TPE), for example a styrene-
ethylene-butylene-styrene block co-polymer, and are mounted
in holes in the wall of the insert. This complicates
assembly of the insert and there is a danger that the
valves may become separated from the insert and be
swallowed. Furthermore, manufacture of duckbill valves
from TPE is problematic, as described in our earlier
specification GB-A-2292708. As TPE is elastic, the slit in
a TPE duckbill valve cannot be formed by the usual method
of mechanical splitting to form a brittle fracture. GB-A-
2292708 describes a method of manufacturing TPE duckbill
valves in which the slit is formed by fluid pressure.
Disclosure of the Invention
According to the present invention, a beverage
container for a carbonated beverage includes a floating
hollow insert comprising an upper moulding and a lower
moulding defining a chamber for containing gas, means
including a one-way duck-bill type valve being arranged to
allow gas to enter the chamber and to exit the chamber and
be jetted into the beverage, upon opening the beverage
container is characterised in that the one-way duckbill
type valve is integrally formed with at least one of the
mouldings.
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According to a second aspect of the present invention,
a floating hollow insert for use in a beverage container
for a carbonated beverage comprises an upper moulding and
a lower moulding defining a chamber for containing gas,
5 means including a one-way duck-bill type valve integrally
formed with at least one of the mouldings, the means being
arranged to allow gas to enter the chamber and to exit the
chamber and be jetted into the beverage upon opening the
beverage container.
Integrally forming the duckbill valve with one of the
mouldings considerably reduces the cost of materials,
manufacturing and assembly of the insert. There is also no
separate component which may become detached from the
insert into the beverage and be swallowed.
As the insert allows gas to enter to pressurise the
insert, the insert need not be pre-pressurised. Gas may
enter the insert through a gas permeable membrane, hole but
preferably through a second one-way valve.
Preferably a first duckbill valve is integrally formed
with the upper moulding, and is arranged ::o allow gas to
enter the chamber, and a second duckbill valve is
integrally formed with the lower moulding to allow gas to
be jetted into the beverage. The variation in the size of
the aperture of the duckbill valve with pressure ensures
the gas is jetted at a substantially constant velocity.
The insert is arranged to float on the beverage with the
first duckbill valve in a headspace above the beverage, and
with the second duckbill valve below the surface of the
beverage.
The first duckbill valve may have a pre-loading, which
requires the pressure difference across the valve to exceed
a pre-determined level for the valve to open. In this way,
after the insert has been pressurized, in the unlikely
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event of the first duckbill valve being submerged below the
surface of the beverage, a small pressure difference across
the valve created as a result of its immersion for example
does not open the valve, and therefore no beverage enters
the insert.
Preferably, the insert is made from a plastics
material, and the duckbill valves comprise an elongate
slit. Preferably the insert is made from a thermoplastic
polymer such as nylon, PET or polyethylene, but
polypropylene is preferred. The polypropylene duckbill
valves of the present invention do not open under pressure
to give an elliptical orifice, as do the prior art TPE
valves. The thin slit causes sufficient shear of the
beverage on jetting, even if a wide slit is used. Because
a wider slit can be used, the slit can have a greater area
when open and a faster response time. Typically, a slit of
2 to 7mm wide is used, which is wider than typical prior
art TPE valves. Gas passage through the slit is
substantially instantaneous compared to TPE valves which
require about a second to fully charge and vent during
flushing of the container with inert gas to remove oxygen
before filling with beverage. Furthermore, manufacture of
the valves is easier than TPE duckbill valves, as the slit
can be formed directly during the moulding cycle and does
not require a separate slitting process as with TPE
duckbills.
Preferably, the two parts of the insert are joined by
hot plate welding or ultrasonic welding although they may
be snap-fitted together.
Preferably, the first duckbill valve is formed at the
bottom of a down pipe extending into the chamber so that
the bottom of the down pipe is adjacent the second duckbill
valve. This feature ensures the insert does not fill with
beverage in the event that valve leakage occurs.
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Preferably, the second duckbill valve protrudes from
the insert and is surrounded by a protective skirt.
Preferably, the upper moulding has a generally
hemispherical domed shape, and the lower moulding is
generally flat. The lower moulding is preferably formed
from thicker material than the upper moulding. This keeps
the insert floating the correct way up with the second
duckbill valve below the surface of the beverage, and
provides good stability. The generally flattened shape of
the lower moulding reduces the floatation height compared
to a sphere of the same volume, hence minimising the extra
space required in the top of a can to accommodate the
insert. ThL',~ design feature enables use of significantly
less material than a simple spherical device of similar
volume. Typically with this design a 10 ml volume device
can weigh only 2.0 g compared to a similar commercial
device weighing 3.5 g. A spherical device of only 2.0 g
would float too high above the beverage surface. This
device has the smaller volume and floats lower.
Preferably, the inside surface of the lower moulding
is shaped to slightly slope towards the second duckbill
valve. This ensures drainage of any liquid out of the
insert which enters during filling or dosing of the can.
The effective volume of the inside of the insert is
preferably between 1 and 20 ml, depending upon the size of
the container, and the type of beverage, but more
preferably the volume is approximately 10 ml.
Brief Description of the Drawings
Particular examples of the present invention will now
be described with reference to the accompanying drawings,
in which:-
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Figure 1 shows in cross-section an example of an
insert for use in a container according to the present
invention;
Figure 2 shows in cross-section the upper and lower
mouldings of an insert for use in a container according to
the present invention before welding;
Figure 3 shows an assembled insert for use in a
container according to the present invention;
Figure 4 shows a beverage container according to the
present invention.
Detailed Description of Preferred Embodiment
Figure 1 shows a cross section of an insert for use in
a container according to the present invention. The insert
1 is formed from an upper moulding 2, and a lower moulding
3 which are hot plate welded together. Figure 2 shows the
two mouldings 2, 3 prior to welding. A first duckbill
valve 4 is integrally formed with the upper moulding 2, and
a second duckbill valve 5 is integrally formed with the
lower moulding 3. The first duckbill valve is formed at
the end of a down pipe 6 which extends from the top of the
insert to a point adjacent the second duckbill valve 5.
The down pipe 6 prevents the insert from filling with
liquid above the level of the first duckbill valve in the
event that valve leakage occurs. The second valve 5 is
surrounded by a protective skirt 10. Figure 3 shows a
complete insert 1.
Figure 4 illustrates a beverage container 11 according
to the present invention. When filling the container 11,
the insert 1 is dropped into the container 11, and the
container 11 and insert 1 are together flushed with inert
gas to remove any oxygen from the inside of both container
11 and insert 1. The container 11 is then filled with
carbonated beverage 12, dosed with liquid nitrogen, and
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sealed. After sealing the container 11, the contents are
heated to pasteurise the beverage.
During heating, the pressure in the container 11
increases. The increase in pressure causes the first
duckbill valve 4 to open and gas from the headspace to
enter the insert 1. The internal pressure of the insert 1
does not exceed the internal pressure of the container 11,
so the second duckbill valve 5 remains closed. After
pasteurisation, the beverage 12 cools and the internal
pressure of the container 11 decreases. The internal
pressure of the insert 1 then exceeds the internal pressure
of the container 11, and the second duckbill valve 5 opens
allowing gas from the insert 1 to be ejected into the
beverage 12. In this way, the internal pressure of the
container 11 and the insert 1 remain in equilibrium.
Upon opening of the container 11, the internal
pressure of the container 11 rapidly vents to atmospheric
pressure. At this time, the internal pressure of the
insert 1 is higher than that of the container 11, and
accordingly gas from the insert 1 is jetted into the
beverage 12 via the second duckbill valve 3. The jet of
gas causes shear in the beverage 12 with a resulting
liberation of a number of small bubbles which, as they
rise through the beverage 12 in the container 11, form
nucleation sites which trigger the liberation of further
small bubbles throughout the beverage 12. As the beverage
12 is poured out of the container 11 and into a receptacle
such as a drinking glass the bubbles from the top surface
of the beverage 12 are intimately mixed with the remainder
of the beverage as it is dispensed. This triggers the
release of further small bubbles throughout the beverage to
give the appearance of dispensing the beverage from
draught.
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The insert 1 with integral duckbill valves 4,5 is made
from polypropylene. Each valve 4,5 is f ormed from an
elongate slit 7 defined by lips 8, 9. The valve 5 allows
fluid to flow through the elongate slit 7 by forcing the
5 lips 8, 9 apart. Fluid is prevented from flowing in the
reverse direction as the lips 8, 9 are forced together.
The use of a duckbill valve 5 for jetting gas into the
beverage is especially beneficial since, as the pressure
10 difference between the inside of the insert 1 and the
inside of the container 11 reduces, the size of the
aperture of the duckbill valve 5 also reduces, and the
velocity of gas jetted into the beverage 12 remains
substantially constant until the internal pressures of the
insert 1 and container 11 are substantially the same. The
velocity of the jet of gas remains constant for a longer
period than when jetted through a simple orifice.
Accordingly, the volume of gas needed to give the required
jetting velocity for the required duration to shear the
beverage is smaller than is necessary where the fluid is
jetted through a simple orifice.
The use of polypropylene duckbill valves 4,5 is also
particularly advantageous. The valves 4, 5 do not open
under pressure to give a full circular orifice, as do the
prior art TPE valves. The thin slit 7 causes sufficient
shear of the beverage on jetting, even if a long slit is
used. Because a longer slit can be used, the slit 7 can
have a greater area when open and a faster response time.
Manufacture of the valves is also easier than TPE duckbill
valves, as the slit can be formed directly during the
moulding cycle and does not require a separate slitting
operation as with TPE duckbills.
The lower moulding 3 of the insert 1 is made with a
greater wall thickness than the upper moulding 2 so that
the insert 1 tends to float with the lower moulding 3
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lowermost since the plastics material has a negative
buoyancy. The upper moulding 2 has a generally
hemispherical shape, and the lower moulding 3 is generally
flat. This reduces the floatation height compared to a
sphere of the same volume, hence minimising the extra space
required in the top of a can to accommodate the insert.
Although the upper and lower mouldings 2, 3 are
illustrated as connected together such that the slits 7 of
the two duckbill valves 4, 5 are aligned, the upper and
lower mouldings 2, 3 may be connected such that the slits
are orientated at any angle to each other.
The int-L-nal volume of the insert 1 depends upon the
beverage contained in the container, but is typically
approximately 10 ml.
