Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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COFFEE IMPREGNATION SYSTEM AND METHOD
Cross-References
This application claims the priority under 35 U.S.C. ~ 119 and applicable
foreign
and international law of the following U.S. provisional patent applications,
which are
hereby incorporated by reference in their entirety for all purposes: Serial
No. 60/337,202,
filed December 6, 2001 and Serial No. 60/380,913, filed May 15, 2002.
Field of the Invention
The invention relates to coffee roasting. In particular, the invention
provides a
new method for impregnating an additive such as a botanical substance into
coffee
beans.
Background of the Invention
Coffee roasting is an art and technique that has been practiced throughout the
world for ages. In recent years, it has become increasingly popular to add
substances
to coffee, for example, to alter the natural flavor or affect of the roasted
coffee bean. A
common method of adding a substance to coffee involves mixing an alcohol-based
flavor substance to the beans after the roasting process is terminated. The
roasted
beans are coated on the surface only. This produces an unpleasant oily coffee
and
diminishes the shelf life of the coffee. Currently, the most common way of
adding
botanical extracts or other substances to brewed coffee is simply to add
liquid drops to
coffee during or after the brewing process. This method is undependable and
inefficient because the drink maker may add varying quantities of the additive
and the
substance may not always be homogeneously distributed in the coffee drink.
There is a need for a reliable method of impregnating enhancing substances
into coffee beans. The method should enable substantial loading of beneficial
substances into coffee. The method should not interfere with optimal roasting
and
brewing techniques.
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Summary of the Invention
The invention provides systems, devices, and methods of roasting coffee in
which an enhancer such as a botanical substance is introduced into coffee
beans
during the roasting process.
Brief Description of the Fi .gores
Figure 1 is a flow-chart illustrating steps in a method of infusing an
additive
into coffee beans.
Figure 2 is a graph illustrating temperature change in a roasting chamber as a
function of time in a method of the invention.
Figure 3 is a perspective view of a coffee roaster.
Figure 4 is a schematic view of a coffee roaster equipped with an automated
additive inj ection system.
Description of the Invention
Coffee roasting has been universally practiced and refined around the world
for
hundreds of years. Coffee roasting is a time-temperature dependent process in
which
physical and chemical changes are induced beginning with green coffee. The
process
begins with the loading of green coffee beans into a roaster, such as the one
shown in
Figure 3. The beans are typically dropped into the roasting chamber through a
hopper,
into a rotating cylinder equipped with internal paddles that keep the coffee
tumbling
and mixing. The rotating chamber is typically preheated to at least about
180°C before
adding green coffee beans to the chamber. The chamber is fueled by a heating
source
that may be electrical, natural gas, gas oil, or wood fueled.
In the rotating chamber, the heat is forced through a controlling air-flow
valve
which is capable of creating a vacuum environment. Convective hot air and
radiant
heat are used to heat the beans. In the first stage of the roasting process,
the green
beans become yellow. The temperature is increased to the boiling point of
water, thus
driving off the moisture in the beans. As the moisture trapped in the beans
turns to
steam, it breaks the cellular structure in the beans abruptly causing the
beans to swell
and to produce an audible crack, known as the "first crack". The loss of
moisture and
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other volatile compounds reduces the weight of the bean by about 14-25%. The
size of
the bean increases by about 40-60%. The first crack usually is reached after
about 15
minutes of heating the beans to a temperature of about 170°-
180°, preferably about
175°C.
The temperature continues to increase to about 180°-215°,
preferably about
182°-194°C. The coffee beans lose most of the pre-existing water
and the volume of
the bean increases (from about 50-100% from the green form). As the
temperature of
the bean escalates, a complex series of chemical transformations occur. This
process is
called pyrolysis. Pyrolysis is the transformation by heat of the chemical
components
in the bean. There are literally hundreds of chemical compounds that make up a
composition of green coffee. These compounds include oils, complex
polysaccharides,
sugars, starches, fats, waxes, and others. Some of these are broken down by
the heat
and driven off. Many compounds that are extracted during brewing are not
present in
green coffee, but instead develop as the coffee is roasted. Some starches are
converted
into sugar which caramelizes, accounting partially for the brown color. As
roasting
progresses, additional complex proteins and organic acids are broken down and
transformed. The bean continues to grow in size, and becomes a darker brown.
To
produce a darker roast, the beans are left in the roaster longer. As the
temperature
continues to build, aromatic oils volatilize and boil toward the surface,
eventually
causing a "second crack" or popping. At the point of the second crack, the
beans are
close to combustion. If the beans are examined under a microscope at this
point they
will appear like a dry sponge ready to absorb water. The roasting process is
typically
stopped near, during, or after the second crack, depending on the roast
master's
obj ectives regarding color and flavor of coffee brewed from the roasted
beans.
The invention provides a method of introducing or impregnating an enhancer
such as a botanical substance, a vitamin, a flavor enhancer, or a therapeutic
substance,
into the coffee bean during the roasting process. An enhancer may be referred
to as an
additive substance which means that a material intended for incorporation in
the
coffee is carried in a solution or suspension formulated to result in a
desired
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concentration of the material in the beans and/or coffee brewed from the
beans. An
objective of the invention is to introduce the additive substance to the bean
at a time
when it is most receptive, particularly, when it is very dry, large, and
porous. For this
purpose, an injection port is provided in the roasting chamber so that a
substance,
typically in a concentrated aqueous solution, can be introduced at the optimal
time
based on timing and temperature data.
After the first crack, the beans are continuously heated until shortly before
the
second crack. For example, the beans may be approximately 175°C at the
first crack,
after which the beans are heated for about three more minutes to a temperature
of
about 184°C. At this point, a water-based concentrate containing the
additive
substances) of choice, is added to the roasting beans through an injection
port in the
roaster, for example, by spraying the concentrate directly at the beans as
they are
stirred and mixed by the rotating paddles. The amount of additive solution
injected is
between 1-15% by weight of the gross weight of the beans being roasted. The
amount
of additive may be from 5-10% or approximately 6% of the weight of the roasted
beans.
Immediately prior to adding the additive solution, a partial vacuum
environment may be created in the roasting chamber by adjusting the air flow
valve(s). This may help draw and distribute the additive into the beans. For
example, a
vacuum environment may be created inside the roasting chamber by at least
partially
or totally closing the air intake channel or valve, and/or by at least
partially or totally
opening the air output channel or valve.
It is preferable to inject the solution before the second crack at which point
the
beans have lost the maximum amount of water and have reached such a high
temperature that sugars and amino acids start crystallizing, and the oils of
the beans
move to the surface which may interfere with the correct absorption of water
into the
bean. The dryness of the beans makes them particularly receptive and absorbent
to the
water-based additive solution. Furthermore, before the second crack, the beans
retain a
certain amount of flexibility which help to attract the additive solution into
the micro
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pores of the beans. However, the invention may be carried out by adding the
concentrate after the second crack or anytime prior to cooling the beans.
Introduction of the water-based solution into the roasting chamber temporarily
slows down or stops the temperature increase in the chamber. The injection may
decrease the temperature of the roasting chamber briefly. Immediately, or
shortly after
completing the injection, the beans are transferred from the roasting chamber
to the
cooling tray. If the beans are left in the roaster too long after the
injection step, then
some active ingredients from the additive may volatilize from the beans.
The cooling process usually lasts about two minutes and produces a reduction
back in size of the roasted coffee bean, thus allowing further sealing of the
additive
substance within the core of the coffee bean. From this point on, the coffee
beans are
impregnated with the extract or additive. The enhanced beans can be packaged,
stored,
ground, and brewed like regular coffee beans. When the beans are ground, the
additive
particles are exposed for reconstitution in brewed coffee and ultimate
assimilation by
the human body.
Figure 1 shows a flow chart listing steps in a method of the invention. Green
coffee beans are first roasted, for example beyond the first crack. A vacuum
environment is created in the chamber. A concentrated aqueous additive
solution is
inj ected into the roasting chamber. Finally, the beans are cooled.
Figure 2 shows a graph illustrating change in temperature in the roasting
chamber as a function of time. The dashed line shows temperature change in the
roasting chamber after green beans are placed in the chamber. Before
introducing the
beans, the chamber is pre-heated to over 200°C. The solid line
represents the
temperature of the beans. After about 15 minutes, the beans reach the first
crack at a
temperature of around 175°C. At this point, the temperature plateaus
slightly and then
increases again to approximately 185°C. The arrow in Figure 2 indicates
the point
where the concentrated aqueous additive solution is injected into the roasting
chamber. The temperature of the beans then plateaus or decreases slightly. The
beans
are then removed from the coffee roaster and allowed to cool.
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Figure 3 shows coffee roaster 10 including roasting chamber 12. Beans are
loaded into chamber 12 through hopper 13. Roasting chamber 12 has an injection
port
14. Cooling device or tray 16 receives beans from chamber 12 after finishing
the
roasting process.
Port 14 may be used typically to check the color of the coffee beans during
the
roasting process. Different methods and mechanisms of injection may be used to
introduce the additive substance through port 14, depending on the roasting
capacity
of the equipment and the effective weight of the coffee being roasted. For
example, a
large syringe may be used to inject the aqueous botanical solution through
port 14. A
spray system may also be used. The dispensing device should be capable of
introducing enough solution to the roaster so that the increase in temperature
is
temporarily stopped, thus avoiding and/or delaying the second crack.
The best time for injecting the solution is shortly before the second crack.
It is
also possible to inject the solution after the first crack. However, generally
more
solution will be absorbed in the beans if the injection is made closer to the
second
crack. It may also be possible to inject the solution after the second crack.
However,
this is less desirable because the beans tend to have more surface oil making
it more
difficult for the solution to penetrate the bean. Moreover, the plasticity of
the beans is
decreased so the beans will not reduce in size as much during the cooling
process.
Each variety of bean, blend and/or additive may have a slightly different best
time for injecting the solution. Generally, the determination about when to
inject the
solution may be a function of time, temperature, and/or visual appearance of
the
beans. It is possible to create a customized routine or timing profile for a
particular
variety of beans and/or blend. Other variables that may affect timing of the
injection
are equipment, ambient temperature, and humidity.
Figure 4 shows schematically a system for controlling and partially or totally
automating the additive injection procedure. Coffee roasting system 30
includes
coffee roaster 32. Roasting chamber 34 is provided with injection port 36.
Compressed air source 38 is connected to port 36 via air line 40. Solenoid
valve 42
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along air line 40 allows opening or closing of air line 40. Removable liquid
vessels
44a and 44b are equipped with shut-off valves 46 and 50, respectively. Liquid
vessels
44a and 44b may contain additive solutions or may also contain water for
washing out
section 51 of line 40. Control panel 60 allows an operator to control the
roasting and
injection process. For example, keys 62 may allow automated processing by pre-
setting parameters such as roaster temperature, injection temperature, and
liquid
volume. Button 64 may allow the operator to go back and forth between
automated
and manual control. Buttons 66 may be used for manual control of the process.
Examples
Example 1
BilberrX-infused coffee beans
I mixed 28 grams of Bilberry extract in 410 milliliters (mls) of water to make
the Bilberry injection solution. The Bilberry extract has approximately 25%
(w/w)
active ingredients. I roasted 15 pounds (lbs) (weight after roasting) of
Sumatran coffee
beans. I injected the bilberry solution near the end of the roasting process.
I transferred
the beans from the roasting chamber to the cooling tray shortly after adding
the
Bilberry solution. I then assayed the coffee beans to determine how much
Bilberry
active ingredient was present in the coffee beans. I determined that there was
0.07%
(w/w) Bilberry active ingredient in the coffee beans.
Example 2
Ginseng used co,~,~'fee beans
I mixed 28 grams of Ginseng extract in 410 mls of water to make the Ginseng
injection solution. I roasted 15 lbs (weight after roasting) of Sumatran
coffee beans. I
injected the Ginseng solution near the end of the roasting process. I
transferred the
beans from the roasting chamber to the cooling tray shortly after adding the
Ginseng
solution. I then assayed the coffee beans to determine how much Ginseng active
ingredient was present in the coffee beans. I determined that there was 0.1 %
(w/w)
Ginseng active ingredient in the coffee beans.
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Example 3
Ginger-inafused coffee beans
I repeated the procedure described in Examples l and 2 except with Ginger
instead of Bilberry or Ginseng. The post roasting assay indicated similar
results.
Example 4
Echinacea-infused coffee beans
I repeated the procedure described in Examples 1 and 2 except with Echinacea
instead of Bilberry or Ginseng. The post roasting assay indicated similar
results.
Although the invention has been disclosed in its preferred forms, the specific
embodiments thereof as disclosed and illustrated herein are not to be
considered in a
limiting sense, because numerous variations are possible. Applicant regards
the
subject matter of his invention to include all novel and non-obvious
combinations and
subcombinations of the various elements, features, functions, and/or
properties
disclosed herein.
