United States Patent [191
in]
3,800,690
Molenaar et al.
[45]
Apr. 2, 1974
[54] COFFEE FILTERING
99/304, 306
[75] inventors: Albert Meijlom MolenaanTerkaple;
'
Melle Veenstra, Joure, both of
Netherlands
[73] Assignee: Douwe Egberts Koninklijke
References Cited
UNITED STATES PATENTS
l,636,l79
7/1927
1,680,5[9
8/]928
Houck
Theehandel N.V., Utrecht,
1,964,]5]
6/1934
Guntrup . . . , . . .
Netherlands
3,139,344
6/]964
Wcisman
Tabakseabriek-Koffiebranderijen
[22]
[21]
[56]
'
Filed:
Dec. 15,197]
Appl. No.1 208,098
Gchlcrt ............................... .. 99/306
... ...
. . . . ..
. . .. . .
99/306
. . . . ..
99/306
, . . . . . , . . . . . ..
99/295
Primary Examiner—Robcrt W. Jenkins
'
Attorney, Agent, or Firm-Baldwin, Egan, Walling
Fetzer
{301'
Foreign Application Priority Data
Sept. 7, I971v
Netherlands ..................... .. '71 l2303
[52]
U S Cl
[51 1
Int. Cl ...................................................... .. A23f
99/295 99/306
[58]
Field of Search .........
ABSTRACT
using a compressed coffee tabletlin a closely ?tting h
dd“
~
99/298, 292, 293, 295,
\
n
[57]
-A coffee ?ltering System having a Single percolation,
i
_
5 Claims, 3 Drawing Figures
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I,
T)
l
l
i .
9/.
11
3,800,690
1
v
2
COFFEE FILTERING
It is observed that in dependence on the type of cof
fee used and the expansion thereof a larger or smaller
The invention relates to a coffee ?ltering method
with a single ?ltration,v as well as to a coffee ?lter for
volume of the holder can be used. If the holder is too
‘applying this ?ltering method and to a pressed tablet of
small the brew does not suf?ciently disintegrate and the
oozing of the water is hampered while in case of too
large a volume all the brew is not suf?ciently extracted.
ground coffee suitable for applying this method, while
use may be made of such a coffee ?lter.
'
The object of the'invention is to provide an improved
To promote disintegration the tablet is kept spaced -
- coffee ?ltering method with a single ?ltration, with a
from the ?lter bottom.
To insure a correct and accurate brewing time the
coffee brew of very high quality and a high extraction
yield and which is particularly also suitable for applica 0 percolating time of the water is preferably determined
tion in a disposable ?lter system.
by the coffee tablet itself and not for instance by the ?l
ter element arranged therebelow. Owing to the use of
pre-compressed coffee a much coarser ?lter bottom
To this end it is proposed to apply a compressed tab
let of roasted and ground coffee, the coffee tablet being
kept in contact-with preheated water for moistening the
coffee tablet during a ?rst period without percolation
of water,’ afterwhich the extraction of the coffee takes
place during a second period while the desired quantity
of water percolates through the ground coffee.
5
than usual can be applied, the only requirement being
that the pore size is just suf?ciently small to prevent
passage of the swollen moistened coffee particles al
most completely.
~ To obtain a good moistening of the coffee tablet and
to prevent the swollen coffee brew from ?oating in the
20 water reservoir, there is preferably arranged between
By employing a pressed coffee tablet and opposing
the water reservoir and the coffee holder a grid having
1 the percolation of water through-the tablet for a certain
openings narrowing towards the interior of the coffee
time, there is time for the water to moisten the coffee,
holder, the smallest opening being in the order of
during which soluble constituents of the coffee are al
0.2-0.5 mm. Gas .present in the extraction chamber
ready released. After that, with. the percolation of the 25 must be able to escape. To promote the gas discharge,
SUMMARY OF THE INVENTION
water, the extraction period of the coffee begins. A cof
fee brew prepared in this manner appears to have par
ticularly good ?avor properties. A compressed tablet
guarantees in all conditions an even ?ltering, while a
brewing time within narrow limits can be maintained. 30
Without the inconvenience of dusting, use'can be made
of very ?nely ground coffee, which will improve the
quality of the brew.
-
steps as de?ned herebelow can be‘taken.
'
The invention will be elucidated with reference to the
drawing showing some embodiments of a coffee ?lter.
BRIEF DESCRIPTION OF THE DRAWING
In this drawing:
>
FIG. 1 vis a vertical section of a coffee ?lter having a
, It has appeared that good results are obtained if the
water reservoir according to the invention;
?rst period takes about one‘quarter of the total brewing 35, FIG. 2 is a top view of the coffee holder of FIG. I;
time and the second period the remaining three quar
ters of this brewing time, the total brewing time being
FIG. 3 is substantially a vertical section of another
between 2 and 6 minutes, moreparticularly between 4 ' construction of a coffee ?lter.
and 5 minutes. The latter case corresponds with a
FIG. 1 shows a coffee tablet 1 received in a holder 2
40
moistening period of about 1 minute.
for ground coffee, said holder being provided at the
According to the invention, a coffee filter for apply
bottom with a ?lter bottom 3. The coffee tablet l is re
ing the- ?ltering method of the present invention has a
tained in the holder 2 by lugs 4. Above the holder there
holder for ground coffee with ?lter bottom, which
is a grid 5, at the bottom of a water reservoir 6. The lugs
and
holder is so constructed that on top of it a reservoir for
a certain quantity of preheated water can be arranged 45
and which can be suitably positioned above a collecting
basin for the coffeebrew, the holder for ground coffee
being adapted to receive and embrace a compressed
tablet ofroasted and ground coffee. On account of the
fact that the coffee tablet is embraced in the holder, it
is prevented that poured water oozes between the wall
of the holder and the-tablet without taking part in the
moistening and extraction of the coffee, while owing to
the density of the tablet the water is stopped during the
moistening time. Although the embrace of the coffee
tablet in a given place is suf?cient to prevent oozing of
water, it has appeared to be efficient to construct the
Y
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4 are also attached thereto.
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DESCRIPTION OF PREFERRED EMBODIMENT
The coffee tablet 1 has the shape of, at least at the
bottom, a ‘substantially ?at disc and is ?ttingly arranged
along the lower edge in a continuous edge 7 in the tab
let holder 2 in such a manner that no water can pass
along the periphery of the tablet. The lower face of the
coffee tablet is spaced some distance (0.5-2 mm) from
the ?lter element 3, which bears on a bearing cross 8.
The upper face of the tablet may be pro?led for a
better control of the moistening phase.
The tablet holder extends conically upwardly from
the support edge '7, so that the tablet has at least 1-2
over a slight height along the lower edge of the periph
mm space on the top to expand radially. Contiguous to
ery and is kept spaced from the ?lter bottom. Owing to 60, the wall of this ex-traction chamber there is on the top
this the tablet can freely expand on all sides, except for
a slightly upwardly inclined wall 9 having ?ve radially
the embraced portion of slight height.v During the
extending recesses 10. The wall 9 has on the lower side
moistening phase the coffee brew swells and the tablet
?ve Wings 11 having a stepped con?guration on the
disintegrates. To receive the expanding coffee brew the
65 lower side for centering the coffee ?lter on a cup. The
holder for ground coffee is constructed with approxi
wall 9 extends into an upwardly diverging wall 12 with
mately three times the volume of the compressed cof
snapping lugs 13. The wall of the water reservoir 6
fee tablet.
'
bears against the wall 12 and is retained by the lugs 13.
holder in such a manner that a coffee tablet is clamped
3
3,800,690
1n the wall of the water reservoir there are a number of
vertical slots 14 extending to a trapped portion 15. The
bottom of the water reservoir 6 with grid 5 is slightly
conical in downward direction. Gases and vapors which
cannot easily escape through the small holes in the grid
5 de?ect laterally via the recesses 10, the space around
the trapped portion 15 and the slots 14. A number of
stacking lugs 16 are arranged on the inner wall of the
water reservoir.
I
The coffee tablet is prepared by compression of
ground and roasted coffee having a grinding size divi
sion of:
13 percent > 0.5 mm
56 percent < 0.5 and > 0.315 mm
18 percent < 0.315 and > 0.16 mm
7 percent < 0.16 and > 0.10 mm
6 percent < 0.10 mm
To prevent disintegration of the table owing to internal
pressure build-up through released CO2, the coffee to
4
after the moistening phase is there question of separate
coffee particles, but these particles have meanwhile in
creased to three times their initial volume, so that a
much coarser ?lter bottom than is necessary for loose
coffee of the same grinding ?neness can be applied. I
has appeared that the material used for tea bags is par
ticularly suitable to serve as a ?lter bottom. This so
called “heat-scalable tea bag paper” of 17 g/m2 is for
example marketed by Messrs. Bolloré in France (type
1,000 K T) or Crompton in Great Britain. By employ
ing such a relatively coarse ?lter bottom the percolat
ing or extraction time is mainly determined by the cof
fee tablet and the coffee particles, as well as the shape
of the tablet holder and not by the ?lter bottom.
The coffee ?lter shown in FIG. 3, having a basket
shaped extraction chamber, is provided with a coffee
tablet l in the tablet holder 2', which is provided in the
water reservoir 6. This water reservoir is provided with
a continuous edge 7', against which the coffee tablet
be compressed may maximally contain about 0.3 per 20 bears sealingly. The tablet holder is provided with lugs
cent by weight of CO2. Besides, the CO2 content may
4’ for retaining the coffee tablet, while the wall extends
not drop below 0.15 percent by weight to prevent too
slightly conically and is provided with longitudinal slots
rapid oxidative decay of the coffee. The compression
having a maximum width of 0.2 mm. This part serves
of the coffee takes place at the lowest possible temper
as a grid 5’. The tablet holder forms part of the water
ature, maximally 30° C. It has appeared that when com 25 reservoir 6', which reservoir has a trapped, conical
pressing, possibly with an inert gas, at a pressure of
200-750 kg/cmz, dependent on the coffee type applied,
wall, with stacking lugs 17 for stacking with another
coffee holder and an internal edge 18 which determines
a suitable ?lter tablet with desired moistening and ex
the water level in the example 140 cm". It is observed
traction time‘is obtained if the tablets are compressed
that in this example the tablet has a diameter of 44 mm
with an average height-diameter ratio between 1:4 and 30 and an average height of 8 mm, while the total height
1:8. With such a tablet an extraction yield between 20
of the tablet holder is 23 mm.
and 30 percent can be obtained if the water-co?’ee
It has appeared that a compressed tablet having a di
ratio ranges between 30 and 10. Thus, for example,
ameter of 44 mm even shows a diameter increase of
with a water-coffee ratio between 20 and 14 and a
about 1 mm within 24 hours after compression. By
height-diameter ratio of the tablet of 1:6 an extraction 35 placing the tablet directly after compression in the con
yield between 22 and 26 percent was obtained. If use
tinuous edge 7’ a very good water sealing along the
is made of water having a temperature between 80° and
lower edge of the tablet is obtained, partly owing to this
100° C a brew of the desired concentration and of suf?
expansion. The reservoir is provided with an annular
ciently high temperature can be obtained if the narrow
pilot surface 19, with which the ?lter element can be
ranges of moistening and extraction time are taken 40 centered on a coffee cup, while in the annular pilot sur
into account. The coffee brew cannot be adversely in
face there are a few radial slots not shown for venting
?uenced by preceding handlings with the coffee ?lter.
the coffee cup. The water reservoir is closed on the top
In a ?lter with loose coffee the coffee easily sags to one
by a possibly transparent cover 20 having an outer an
side, as a result of which the ?ltration is not optimal.
nular
pilot surface 21, with which the cover is centered
For a normal cup of coffee about 140 cm3 hot water 45 on the water reservoir and an inner annular pilot sur
is poured in the water reservoir 6, the grid 5 insuring
a good distribution of the water over the tablet to be
face 22, between which, in the reverse position of the
cover, the lower side of the ?lter can come to rest after
moistened. The total volume of the extraction chamber
use, so that the cover serves as a saucer.
in the tablet holder 2 is, dependent on the properties of
On top of the coffee holder 2' there is provided a cap
the brew, about three times the volume of the coffee
23 partly extending over the slots in the grid 5. Below
table 1, in such a manner that the swollen brew ?lls the
the edge of this cap an air cushion is maintained, so that
space almost completely. If the water is poured on, the
when the water is poured on, the upper ends of the grid
coffee tablet initially prevents the water from percolat
slots remain active for venting and for the gas dis
ing, while the coffee particles swell owing to the moist
charge. The top of the coffee holder has an insert 24 to
55
ening. About after one minute the percolation of water
reduce the central space at the top of the coffee holder.
starts.
lf ground coffee can also deposit there, it appears that
The openings in the grid 5 are slightly funnel-shaped.
it is less or hardly extracted. Owing to the different
The grid contains at least 50 small holes having a diam
shape of the coffee holder and the position of the grid
eter of maximally 0.5 mm. The dimensions are such
slots the ?lter shown in FIG. 3 provides a less bitter,
that the coffee in the water reservoir 6 is almost com 60 lighter ?avor of the brew than the ?lter shown in F 1G.
pletely prevented from ?oating. By keeping the nar
rowest portion of the openings on the tablet side of the
1, in which the ground coffee is almost completely ver
tically percolated.
_
grid, loosened coffee parties which possibly come into
The water reservoir and the tablet holder may be
the openings and which expand therein when moist
65 manufactured by injection molding of polystyrene 466
ened, will float in the water and will not clog the grid.
i of B.A.S.F., for instance with a wall thickness of 0.6
Since the ?ne, ground coffee is compressed, almost no
mm. Of course also different materials are suitable,
loose coffee particles will reach the ?lter bottom. Only
provided they resist water of 95—98° C. The ?lter as
3,800,690
5
6
sembly according to the invention is- very well suitable
for a disposable packing.
,
2. A coffee ?lter according to claim 1, wherein the
It is observed that the invented method and the ?lter
applied can also be used for making beverages other
than coffee, for instance, tea, cocoa or the like. The
last mentioned means includes means operable for
holding a coffee tablet at a slight height above the
lower edgeof the periphery of said holder and is kept
spaced from said ?lter bottom.v
compressed tablet may also comprise additives, like
sugar or milk powder_
What is claimed is:
'1. A coffee ?lter comprising a holder for ground cof
fee, said holder having a ?lter bottom, a reservoir
mounted on the top of said holder and adapted to re
ceive a certain quantity of preheated water, said ?lter
3. A coffee ?lter according to claim 1 characterized
in that the holder for ground coffee has approximately
three times the volume of the pressed coffee tablet.
4. A coffee ?lter according to claim 1, characterized
in that said ?lter bottom has such a porosity that water
swollen coffee particles can not precisely pass.
being adapted to be positioned above a collecting basin
5. A coffee ?lter according to claim 1, characterized
for the coffee brew, said holder having means adapted
to receive and closely embrace a pressed tablet of 15 in that the coffee holder is separated from the water
roasted and ground coffee in a liquid-tight peripheral
reservoir by a grid having openings of which the small
relation therewith effective to prevent any liquid from
est size is in the order of magnitude of 0.2-0.5 mm.
flowing between the edge of said tablet and the holder.
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