Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
BACKGROUND OF THE INVENTION
Pelleti~ed coffee percolator packages such as des-
cribed in commonly-assigned U.S. Paterlt No. 3,511,666, have
recently become available to the consumer. Generally, these
products are compressed doughnut shaped pellets of roasted and
ground coffee which are wrapped or packaged in porous filter
paper material. The covered pellets are dapted to fit into the
basket of conventional home percolators and have the advantages
of reducing sediment in the brewed beverage and also provide a
neat and efficient way in which to dispose of the spend coffee
grounds.
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11~ 707
These coffee pellets are formed under substantial
pressure so that a self-sustaining pellet capable of being
wrapped or packaged is produced while at the same time the
pressing operation is sufficient or effective to release at
least 10% more extractable solids than would be obtained from
an e~uivalent charge of fresh R & G coffee, but insufficient
to disrupt the coffee particles to the extent that coffee
lipids are expressed which would introduce an undesirable oil
film or slick in the percolator brew. Generally it has been
found that the amount of pressure applied to the coffee should
be kept under 16,000 p.s.i. and preferably under about
13,000 p.s.i.
It has,however, been found that compressing at below
the above mentioned pressure limits for a period of time
insufficient to release substantial coffee lipids does not
assure the production of a coffee pellet which will, even when
enclosed in a suitable wrapping of filter material, withstand
the rigors of packaging and shipment without breaking.
Breaking of the coffee pellet within the filter wrapping is
undesirable since fine particles of ground coffee are then able
to pass through the filter wrapping to produce an unsightly
dust or powder on the surface of the wrapped pellet or within
the container (e.g. metal can) which may contain several of the
percolator packages. Additionally it is also desirable to
prcsent to the consumer an undivided, structurally-rigid pellet
within the f e- rapping.
SUMMARY OF THE INVENTION 113~7'~ ~
It has now been found that by substantially reducing
mixing in the chaff normalizer, which is an integral part of
commercial coffee grinding equipment such as the Gump Coffee
Granulizers and surns Coffee Grinders, the structural integrity
of compressed coffee pellets of roasted and ground coffee can be
increased. The chaff normalizer is described by Sivetz, "Coffee
Processing Technology", vol. 1, page 244 (The Avi Publishing Co.
1963) as a high speed mixing screw located below the grinding rolls
and used to mix particles of chaff with the ground or granulated
coffee. The mixing of the coffee with the chaff causes the
chaff to break up and to be less conspicuous against the back-
ground of ground coffee.
It has also been found that the chaff normalizer,
in addition to breaking up particles of chaff, also has the
effect of rounding-off or smoothing the particles of subdivided
coffee. The present invention has shown that when mixing in
the chaff normalizer is reduced, presumably allowing the particles
of subdivided coffee to retain their sharp, discrete edges,
stronger pellets of compressed coffee can be formed. While it
is not wished to be limited to such, it is believed that when
the particles of subdivided coffee possess discrete edges,
a greater interlocking effect is achieved when the particles are
placed under compression. Thus reducing mixing in the chaff norm-
alizer results in imparting increased structural integrity to
compressed
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1{)~'~707
pellets of roasted and ground coffee.
The subdivided coffee is compressed into a self- ¦
sustaining pellet, preferably doughnut-shaped, under a pressure
of less than 16,000 p.s.i. and preferably between about 8,000
and 13,000 p.s.i. for a period of time insufficient to release
substantial coffee lipids. The resulting pellet is then
wrapped in a suitable filter material, such as described in
the aforementioned U.S. Patent No. 3,511,666.
DETAILED DESCRIPTION OF THE INVENTION
The subdivision of roasted coffee beans is usually done
in progressive steps, since notching out the desired particle .
size from the whole bean is not feasible. Commercial Gump
Coffee Granulators include a total of four gradual reduction
stations, comprising two cracking or breaking stations and
two granulating or grinding stations, and a chaff normalizer.
The two breaking stations are formed by double reduction breaker
rolls, and the grinding stations are formed by separate sets of
coarse grinding and fine grinding rolls. This type of Gump
grinding, described by Sivetz, "Coffee Processing Technology,"
vol. 1, page 244-245 is so widely used that a question is
raised by Sivetz of whether other types of grinder might not
be applicable to coffee.
As will be recognized by those skilled in the art
the ground coffee is allowed to fall directly from the fine
1U4'~7U7
grinding rolls into the normalizer. The norsnalizer is operated
in a full or choke condit-ion so that the ground coffee is
throughly mixed as it passes through the normalizer usually
exiting through a pcrt located at the end of the normalizer.
While passing through the normalizer the moving bed of ground
coffee is subject to high speed mixing by a mixing screw and/or
a series of rotating paddle blades.
According to this invention the ground coffee is not
significantly mixed. Preferably, because of the design of the
equipment, the ground coffee is allowed to pass through a por-
tion of the normalizer and to exit through an open port in the
bottom of the normalizer. Thus substantially all the ground
coffee falls freely out of the normalizer by means of gravity
as opposed to most of the coffee being forced out the end of
the normalizer in an horizontal direction. In this manner
significant mixing of the ground coffee is avoided and the
subdivided particles of coffee are permitted to retain discrete
edges. It has been estimated that when proceeding in accord-
ance with the preferred embodiment of this invention mixing is
reduced at least 75% over that which occurs during conventional
use of the entire length of the normalizer.
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Chaff normalizers are usually divided into two
compartments by means of a fixed wall, which wall has a
relatively smal~ open part to provide communication between
the two compartments. This arrangement is thought to increase
the efficiency of the mixing within the normalizer. When
preparing roasted and ground coffee for pelletizing in
connection with this invention the granulated coffee is passed
out of the bottom of the normalizer before it can pass through
the open port into the second compartment.
The ground coffee exiting from the normalizer is .
usually passed directly onto a scalper screen in a manner
well-known to those skilled in the art and the screened coffee
is then collected and held for degassing.
The degassed coffee is fed to a pelletizing apparatus
which is designed to receive a charge of roasted and ground
coffee and to compress the charge into a self-sustaining pellet.
As previously indicated the apparatus exerts a pressure,
preferably between about 8,000 and 13,000 p.s.i. for a period
of time which avoids expressing coffee lipids from the coffee.
The pellet may be made in the form of a doughnut-shaped tablet,
wafer or other desired shape, the doughnut shape being preferred
for obvious reasons. The compression step can be accomplished
by several chemical engineering apparatuses known to the art
as illustrated by U.S. Patent Nos. 3,511,666 and 3,607,299.
~ 7
No criticality exists in regard to the wrapping or packaging
step this being known to the art by the two above-mentioned
patents which also disclose suitable water permeable or porous
filter material for use in this invention.
This invention is further described but not limited
by the following example.
Example
A coffee blend was divided into two batches, one
batch being passed through a commercial Gump Granulizer (Model
777) in a standard fashion (i.e. ground coffee exits from end
of normalizer), the second batch passing through the granulizer
with substantial by-pass of the normalizer (i.e. ground coffee
falls by gravity out of the first compartment of the normal-
izer). The two batches of ground coffee were then compressed
into doughnut-shaped tablets in a Stokes (Model 340), 15
station, dual-feed, rotary press, the compression pressure and
operating speed of the press being varied in order to obtain
tablets having varying amounts of crush strength. The crush
strength, measured in lbs., is the weight which the tablet,
standing on edge, can sustain before the tablet breaks. The
compressed tablets were than placed between two sheets of a
non-woven fabric made of mixed polymeric fibers with a coating
of non-toxic bland resin binder and heat sealed around the
peripheral protions of the doughnut.
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104;~7~)7
The compression needed to achieve a particular
crush strength was found to be lower for the un-normalized
ground coffee ~econd batch)of this invention than for the
regular, normalized coffee (first batch). This was illustrated
by the fact that high crush strengths of 5.5. and 6.0 could not
be achieved at high operating speeds with the normalized coffee
without exceeding the maximum tonnage capability of the press.
It has additionally been found that, even at the same level of
tablet crush strength, the wrapped tablets produced from .
normalized roasted and ground coffee do not have the structural
integrity of the wrapped tablets produced from the un-normalized
roasted and ground coffee. This was illustrated by a shipping
test wherein the wrapped tablets were vacuum packed in metal
cans (ten per can) and shipped a total of 3000 miles by rail.
The percent breakage of the tablets for varying crush strengths
and varying press operating speeds are set forth in Table I.
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