Note: Descriptions are shown in the official language in which they were submitted.
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F 7019 (R)
INFUSION BAG
This invention relates to an infusion bag comprising at
least two layers of a liquid, permeable filter material
which are joined at the edges so as to form at least one
pouch containing an infusible material.
Infusion bags of this type are well known and are
usually intended for preparing a single cup of beverage,
such as coffee or tea, by infusion in hot water, but
also infusion bags with herbs and spices or soup are
well known. The bags may incorporate a handle to
facilitate suspension of the bag in the infusion liquid
and removal of the bag from the liquid. In some forms,
the handle constitutes a short length of string stapled
or sealed to the bag. The free end of the string may
have a tag attached for easy handling.
In its simplest and commonest form, such a bag is just a
simple envelope or pouch sealed on all edges and made of
a liquid, permeable filter material which, at one side,
can be heat-sealed. The liquid, permeable filter
material may be filter paper, which may comprise
synthetic fibres, or it may be a perforated plastic
material.
While an infusion bag has many advantages and is rather
easy to produce and convenient to use, it has also some
drawbacks. The first disadvantage arises after the bag
has been immersed in the infusion liquid for the
required period of time to prepare an acceptable brew
and it is desired to remove the bag from the liquid. The
infusible material in the bag and the material of the
bag itself have absorbed an appreciable quantity of the
infusion liquid and this residual liquid drops from the
bag as it is withdrawn from the infusion liquid and
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usually such a dripping bag is an inconvenience for the
user.
The second disadvantage is that the rate and the amount
of extraction from such an infusion bag is not always
optimal. Attempts have been made to remedy this by
providing a so-called two-chamber bag, in which two
pouches or envelopes with infusible material are
attached to each other at the top and usually also at
0 the bottom, so that the infusion liquid may pass between
the two pouches and at all sides enter into the bag. The
disadvantage of these bags resides in their requiring
complicated machinery for their production.
There is therefore a need for an infusion bag which can
be produced rather easily but which does not exhibit the
disadvantage of dripping for a long period of time after
it has been taken out of the infusion liquid and which
at the same time exhibits an acceptable rate and amount
of extraction of the bag.
In has now been found in extensive experiments that such
an infusion bag with the required short drip time (and
the associated reduced mess) may be obtained by
providing an infusion bag which, compared to the
standard rectangular, square or round tea bag, has an
appreciable shorter drip time and which can easily be
removed from the infusion liquid.
It has been found during the experiments, particularly
with tea bags, that if the bag is brought into the hot
infusion liquid (or the boiling infusion liquid is
poured upon the tea bag), the small air pockets present
in the tea leaf material are forced out of it and this
discharged air is transferred from the tea leaf material
to the top area of the tea bag. If at the same time the
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F 7019 (R)
bulk of the expanded tea leaf material remained confined
in the tea bag near the bottom drain edge, the degassing
action created a flotation, which caused the tea bag to
float in the infusion liquid like a buoy with the top
area containing the air sticking out of the infusion
liquid, thus offering a convenient lift point.
~uring the experiments it has been found that the
infusible material, in this case the tea leaf material,
should be kept tight together, which can be effected by
retaining the bulk of the tea leaf material near the
bottom drain edge of the infusion bag and keeping it
there in a relatively confined area.
Furthermore, it has been found that it is essential,
when lifting the infusion bag out of the cup, that the
bottom drain edge of the infusion bag in wet state be
substantially straight and in an essentially horizontal
position. It was found that this could, for example, be
advantageously effected by providing the bottom seal of
the infusion bag in dry state in the form of an arc of a
circle.
The substantially straight and essentially horizontal
position of the bottom drain edge of the infusion bag
could not be reached when using a standard rectangular
or square tea bag and therefore the minimized drip
infusion bag according to the present invention differs
appreciably from the form and shape of a standard
infusion bag.
Therefore, the present invention relates to a minimized
drip infusion bag, which is characterized in that it is
provided with means to keep the infusion bag buoyant
upon contact wi.th the infusion liquid, the bottom drain
edge of the infusion bag in wet state being
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substantially straight and in an essentially horizontal
position.
A floating infusion bag has been described in United
States Patent Specification US-A-3,gO9,215 (Tetley
Inc.). In this patent it has been proposed to provide an
infusion package, such as a tea bag, with means for
holding the bag in a horizontal floating position during
steeping, so that the bag is almost parallel with and at
about or near the surface of the water. Suitable means
are attached to the bag in the form of closed cell foam
strips or air filled chambers attached over the entire
length of the bag.
Preferably, the present invention relates to a minimized
drip infusion bag, which is characterized in that it is
provided with (a) means to restrain the bulk of the
infusible material near the bottom drain edge and/or (b)
means to restrain the gas evolved upon contacting the
infusible material in the bag with hot infusion liquid,
after its transfer to the top area of the bag in that
area, said bottom drain edge of the infusion bag in wet
state being substantially straight and in an essentially
horizontal position.
The means to restrain the bulk of the infusible material
near the bottom drain edge of the infusion bag can first
of all be based on the friction between the infusible
material and the interior of the infusion bag. Thus, the
infusible material and/or its particle size may be
selected such that together with the relative roughness
of the inside of the selected infusion bag material a
maximum friction occurs, which is sufficient to keep the
infusible material near the bottom drain edge of the
infusion bag.
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Another means to restrain the bulk of the infusible
material near the bottom drain edge of the infusion bag
is to fold over or crease the upper part of the infusion
bag along a horizontal folding line extending over the
full width of the infusion bag, and which is located in
the vicinity of the top surface of the infusible
material contained in the lower part of the infusion
bag.
Still another means to restrain the bulk of the
infusible material near the bottom drain edge of the
infusion bag is to provide physical restrictions which
are located over the surface of the infusible material
contained in the lower part of the infusion bag. These
physical restrictions may consist of adhered or sealed
areas, preferably heat-sealed areas, extending from the
lateral seams of the infusion bag into the free area of
the bag in the form of bars, fins, diamonds, half-
circles and the like shapes, said adhered or sealed
means being located over the top surface of the
infusible material contained in the lower part of the
bag. The sealed areas restrict the upward movement of
the infusible material but still provide sufficient
passageway for the air during the degassing action of
the infusible material when the infusion bag is wetted
by immersion in the infusion liquid.
The physical restriction may also consist of restricted
adhered areas like spot seals located in the free
surface area of the infusion bag above the top surface
of the infusible material contained in the lower part of
the infusion bag. The spot seals are preferably heat
seals and may have any size and shape, as long as a free
passage of the air during the degassing is guaranteed.
Instead of spot seals, at least one staple or a stitch
may also be used.
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The means to restrain the gas evolved upon contacting
the infusible material in the bag with infusion liquid
after its transfer to the top area of the bag in that
area may vary widely, the main purpose being to keep the
infusion bag buoyant, preferably with the top of the
infusion bag protruding above the level of the infusion
liquid in the container into which the infusion bag is
brought. This may, for example, be effected by the
provision of a certain shape of the infusion bag in
which the horizontal distance between the lateral seals
diminishes towards the top of the bag and the lateral
seals are isosceles so as to form a triangular or
trapezial bag.
FurthermorQ, the means may be the provision of a
coating, preferably a dehesive coating, on the interior
surface area of the infusion bag in the top area of the
bag, extending from the top of the bag towards the
bottom over at most half the perpendicular distance
between the top and the bottom drain edge of the
infusion bag.
Another means to restrain the evolved gas in the top
area of the bag is to treat the top half area of the
material from which the infusion bag is prepared in such
a way, e.g. by heating it, that its porosity is reduced
to such an extent that the gas occluded in the top space
of the infusion bag cannot leave this space by diffusing
through the bag material.
If the amount of occluded gas in the infusible material
contained in the minimized drip infusion bag according
to the present invention is too small to keep the
infusion bag in a buoyant condition, an innocuous
foaming agent evolving a gas when contacted with the
infusion liquid can be provided in the interior top
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F 7019 (R)
space of the infusion bag according to the present
invention.
In another embodiment, a certain amount of encapsulated
gas, e.g. encapsulated in a plastic container like a
sphere or an ellipsoid container, may be provided in the
interior top space of the infusion bag according to the
present invention.
0
In still another embodiment, a piece of material
imparting buoyant properties to the infusion bag may be
provided in the top area of the infusion bag according
to the present invention.
Preferably, the means to restrain the bulk of the
infusible material near the bottom drain edge of the
infusion bag according to the present invention are used
in conjunction with the means to restrain the gas
evolved upon contacting the infusible material in the
bag with infusion liquid after its transfer to the top
area of the bag in that area, or with the other means of
keeping the infusion bag according to the present
invention in buoyant condition, used if insufficient gas
is evolved from the infusible material contained in the
infusion bag upon wetting with the infusion liquid.
In its simplest embodiment, the infusion bag according
to the present invention may have the form of a segment
of a circle with a truncated apex. Usually, however, the
infusion bag according to the present invention will
have the form of an isosceles trapezium. The liquid,
permeable filter material may be standard filter paper
as normally used in the manufacture of infusion bags,
such as tea bags. Preferably, this filter paper is heat-
sealable, at least at one side of the paper. The filter
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F 7019 (R)
paper may also comprise synthetic fibres or may consist
of perforated plastic material, and may at least be
partially provided with a coating material. It may also
have been impregnated with ingestible colouring agents,
flavouring agents, sweetening agents, pH-adjusting
agents, and the like substances.
The infusion bag may also be provided with a string to
which, at the end, a tag may be attached.
0
The infusible material may be a tea-comprising material,
a coffee-comprising material, a herbs-comprising
material, or a mixture of tea and herbs, a spices-
comprising material, such as spice mixtures or soup
mixtures and bouillon powders, a material comprising a
flavouring agent, and mixtures of these materials.
Although, preferably, the infusible material is
ingestible, also non-ingestible materials may be used,
such as dyes.
The invention will now further be described with
reference to the accompanying drawings, in which :
Fig. 1-11 show front views of various infusion bags
according to the present invention; and
Fig. 12 shows a relation between water-retention
weight in grams and drip time in seconds for two
infusion bags according to the present invention (A,B),
a standard round tea bag (C) and a standard rectangular
tea bag (D);
Fig. 1 shows a front view of an infusion bag 1
according to the present invention, which includes two
layers 2,3 of a liquid, permeable filter material, which
are joined together along the lateral seals 4,5, the
bottom seal 6 and the top seal 7, preferably through
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heat-sealing. Heat-sealed areas are depicted in hatched
lines in all drawings.
In Fig. 1, the infusion bag has the form of a segment of
a circle with truncated apex and the angles between the
lateral seals 4,5 and the top seal 7 and the bottom seal
6, both in the open area 8 (which is the area available
for infusion) and along the outer edge of the bag 9, are
xounded off. In this type, both the upper edge 10 and
the lower edge 11 of the bottom seal 6 constitute an arc
of a circle.
In Fig. 2, another embodiment of the infusion bag
according to the present invention has been shown in an
isosceles trapezial form. Here, both the upper edge 10
and the lower edge 11 of the bottom seal 6 also
constitute an arc of a circle but, as has been shown in
Fig. 4, it is also possible that only the upper edge 10
of the bottom seal 6 constitutes an arc of a circle,
whereas the lower edge 11 of the bottom seal 6 is
horizontal. The reverse may also occur, in which the
upper edge 10 of the bottom seal 6 is horizontal and the
lower edge 11 of the bottom seal 6 constitutes an arc of
a circle. This modification has not been shown in the
Figures.
The horizontal distance of the top seal 7 between the
lateral seals 4,5 may be different in length, as may be
seen when comparing Fig. 2 and Fig. 4.
Fig. 3 shows another embodiment of the infusion bag
according to the present invention, also in an isosceles
trapezial form. Here, the top seal 7 and the bottom seal
6 are both horizontal and all angles between the lateral
seals 4,5 and top seal 7 and bottom seal 6, both along
the open area 8 and along the outer edge 9 of the
infusion bag, are rounded off. It is possible, however,
F 7019 (R)
- 10
that only the angles in the open area 8 or along the
outer edge 9 of the infusion bag are rounded oîf.
Fig. 5 shows a further embodiment of the infusion bag
according to the present invention in an isosceles
trapezial form, in which, at a distance from the top
seal 7, the two layers 2,3 of the liquid, permeable
filter material are joined by heat-sealing over at least
part 12,12' of the horizontal distance between the
lateral seal 4,5. Although in Fig. 5, the bottom seal 6
is horizontal, the lower edge 11 or the upper edge 10,
or both, of the bottom seal 6 can constitute an arc of a
circle.
In Fig. 6, an embodiment of the minimized drip infusion
bag according to the present invention has been shown,
in which the means to restrain the bulk of the infusible
material near the bottom drain edge 10 is formed by
folding over the top part of the infusion bag along
folding line 13. Although in this Fig. 6 the bottom seal
6 is horizontal, the lower edge 11 or the upper edge 10
(not indicated), or both, of the bottom seal 6 can
constitute an arc of a circle.
In Fig. 7, another ambodinent of the minimized drip
infusion bag according to the present invention has been
shown, in which the means to restrain the bulk of the
infusible material near the bottom drain edge of the
infusion bag is a physical restriction which consists of
a seal area in the form of two half diamonds 14
protruding inwardly from the lateral seals 4,5.
In Fig. 8, a further embodiment of the minimized drip
infusion bag according to the present invention has been
shown, in which the means to restrain the bulk of the
infusible material contained in the bag near the bottom
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drain edge of the infusion bag is a physical restriction
which consists of two round point seals 15 connecting
the two layers of a liquid-permeable filter material of
which the infusion bag has been made. The point seals
may be heat-sealed but can also be effected by using an
innocuous adhesive material.
In Fig. 9, yet another embodiment of the minimized drip
infusion bag according to the present invention has been
shown, in which the means to restrain the bulk of the
infusible material contained in the bag near the bottom
drain edge of the infusion bag is the specific shape of
the bag, of which the interior surface of the permeable
filter material has a high friction coefficient. In this
embodiment, the lower edge 11 of the bottom seal 6 may
also be horizontal.
In Fig. 10, a further embodiment of the minimized drip
infusion bag according to the present invention has been
shown, in which the means to restrain the bulk of the
infusible material contained in the bag near the bottom
drain edge of the infusion bag are formed by the
specific shape of the bag in conjunction with the two
ellipsoidal heat-seal spots or adhesive spots. In this
embodiment, the lower edge 11 of the bottom seal 6 may
also be horizontal.
Finally, in Fig. 11, still another embodiment of the
minimized drip infusion bag according to the present
invention has been shown, in which the means to restrain
the bulk of the infusible material in the bag near the
bottom drain edge of the infusion bag is formed by the
constriction in the centre part of the hour glass-shaped
infusion bag. In this embodiment, the lower edge 11
and/or the upper edge 10 of the bottom seal 6 may also
be horizontal.
F 7019 (R)
12
In all embodiments as shown in Fig. l-11, the liquid
permeable material can be filter paper, but also
perforated plastic material. Advertisement can also be
printed on the outside of the infusion bag on the two
layers 2,3 of the liquid, permeable material.
In Fig. 12, the results of some experiments have been
graphically depicted. The water weight, which is the
weight of the water in grams retained by the brewed
infusible material (in this case black tea leaf), is
plotted along the vertical axis of the vertical axis and
the drip time, which is the time in seconds measured
from the moment at which the infusion bag is raised
above the hot water (90C) level till the moment when
the period of time between two successive drops is more
than 10 seconds, is plotted along the horizontal axis.
Line D relates to the results obtained with a standard
rectangular tea bag (75 mm x 65 mm); line C depicts the
results obtained with a standard round tea bag (diameter
65 mm); line B relates to the results obtained with a
tea bag according to the present invention as shown in
Fig. 3, and line A relates to the results obtained with
a tea bag according to the present invention as shown in
Fig. 2. It is clear from these results that the tea bags
according to the present invention provide the optimum
drip time, whereas the brew obtained with both tea bag
types was considered to be excellent.
