Note: Descriptions are shown in the official language in which they were submitted.
3~S6
BACKGROI~ND OF THE INVENTION
Field of the Invention
The present invention relates to a process for
removing caffeine fronl raw coffee. More specifically, the
present invention relates to a process wherein raw co~fee
is contacted with an aqueous liquid to extract the caffeine
therefrom and the resulting liquid is contacted with an
adsorption-agent that has been pre-loaded with at least one
substance present in and extractable fronl ~he coffee or with
a substitute therefor having a corresponding molecular struc-
10 ture and size.
Description of the Prior Art
It is known in the art that caffeine may be removed
fronl raw coffee by various techniques. However, such known
techniques generally present substantial disadvantages which
detract fronl their use. For exanlple, in practically all well-
known processes for decaffeinating raw coffee used today,
the coffee is extracted using organic solvents. A main
disadvantage of this process resides in the fact that at
least a trace of the solvent remains in the treated coffee.
, 20 This residuum may adversely affect the taste and/or aroma
of`the brewed coffee product thereby decreasing its palat-
ability.
In order to avoid the use of organic solvents, it
is also known to extract the raw coffee with an aqueous
liguid, to remove the caffeine fronl the extract solution by
adsorption on an adsorption agent and subse~uently to conlbine
.
. : , . . .
36~i6
the remaining extract substances with the coffee beans. The
disadvantage of the well-known process~s of this type is
that the adsorption agent, more particularly activated
charcoal, adsorbs considerable quantities of other substances
in the coffee besides the caffeine which thereby are lost
and thus results in a product having a lower extract content.
The search has therefore continued for a process
which will eEfectively remove caffeine fronl raw coffee with-
out imparting an undesirable taste and/or aroma to the
10 final product or substantially lessen the extract content.
This invention is the result of that search.
SUMM~RY AND OBJECTS OF THE INVENTION
Accordingly, it is a general object of the present
invention to provide a process which eliminates or substan-
tially obviates the problems of the prior art.
It is a nlore specific object of the present inven-
tion to provide a process for removing caffeine from raw
coffee which does not adversely affect the quality of the
final product.
It is another object of the present invention to
provide a process for removing caffeine from raw coffee
whereby other extractable substances in the coffee are
substantially not lost.
These objects and advantages of the present inven-
tion will become apparent from the following summary and
description of the preferred embodiments of the present inven-
tion.
3~56
In one aspect, the present invention provides a
process for decaffeinating coffee whereby the caffeine is
extracted from raw coffee by nleans of an aqueous liquid and
is adsorbed from the resulting liquid extract by contact with
an adsorption agent. The improvenlent of the process comprises
loading the adsorption agent prior to its use for adsorbing
caffeine with at least one other substance present in and
extractable from the raw coffee or with a substitute for said
extractable substance having a nlolecular structure and size
10 corresponding to said extractable substance whereby the
adsorption of coffee extract substances other than caffeine
is decreased.
In another aspect, the present invention provides
a process for extracting caffeine fronl raw coffee with an
aqueous liquid and adsorbing the caffeine from said aqueous
liquid by contact with a solid adsorption agent. The process
comprises loading an adsorbent with an extractable substance
that is co-extractabIe from raw coffee with caffeine or a
substitute for said extractable substance having a molecular
20 structure and size corresponding to said extractable substance
and thereby forming a pre-loaded adsorption ayent, passing
an aqueous liquid through an extraction zone containing a
batch of raw coffee and then through at least one column
containing said pre-loaded adsorption agent.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As stated above, the present invention relates to
a process for removing caffeine from raw coffee by extracting
~2;3~56
caffeine from the raw coffee with an aqueous liquid and con-
tacting the resulting extract with an adsorption agent that
has been pre-loaded with at least one selected non-caffeine
substance.
Pretreatment of the Adsorption Agent
~ n adsorption agent such as activated aluniina,
silica gel or, preferably, activated charcoal, is charged
with at least one coffee extract substance which is to be
kept in the raw coffee to be decaffeinated or with a substi-
10 tute substance having a similar molecular structure andmolecular size. This "pre-loading" enables the adsorption
agent, when it is brought into contact with a coffee extract
solution, to adsorb at n~ost a small additional amount of the
coffee extract substance. In this regard, the pre-loading
can be regulated such that prior to contacting the adsorp-
tion agent with the coffee extract solution, there exists a
substantial equilibriun~ between the concerned extract
substance in solution and that contained on the adsorption
agent. Accordingly, the selectivity of the adsorption agent
20 for caffeine is increased.
The selection of the pre-loading substances is
generally deternlined by the availability of acceptable
substances and prevailing economic conditions. ~ pre- -
loading substance which consists o a complete caffeine-
free coffee extract would indeed be ideal but can usually be
obtained only at prohibitive cost. However, nunlerous sub-
stances exist which substantially reduce the loss of desired
extract substances while pernlitting caffeine adsorption.
2365G
More particularly, essential coffee extract substances which
are adsorbed to a considerable degree by activated charcoal
are various sugars and chlorogenic acid. In order to reduce
the adsorption effect of activated charcoal for these sub-
stances, it can be pre-loaded with sucrose and/or glucose
and/or other carbohydrates. Additionally or instead of the
latter, chlorogenic acid can also be usedl but is presently
substantially nlore expensive than sucrose in the form of
cane sugar. Other acceptable coffee extract substances or
lO substitutes` therefor will be apparent to those of ordinary
skill in the coffee art.
For the pre-loading, an aqueous solution of the
pre-loading substances is brought into contact with the
adsorption agent. More specifically, the solution having a
pre-deternlined concentration of the pre-loading substance or
substances is placed in a heatable tank, heated to a speci-
fied tenlperature and then punlped through a colunm containing
the adsorption a`gent in circulation from the tank. The
concentration of the pre-loading substances in the solution
20 is regulated such that they are substantially equal to the
concentrati~ns of the corresponding extract substances in
the coffee extract solution. The temperature of the pre-
loading solution can range from about 20C. to about 100C~
and pre~erably from about 70C. to about 90C. In a column
containing about 500 kg. of activated charcoal and having a
flow rate of fronl about 5 to about 25 m3/hr., preferabl~
from about 5 to about 10 nl3/hr., the pre-loading period
generally requires from about 2 to about 10 hours, prefer-
ably fronl about 6 to about 8 hours. The pre-loading may
3O occur without recirculating the pre-loading solution wherein
the adsorption agent is allowed to remain with the solution
in a container heated to the desixed temperaturP.
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There is a further beneficial effect on the quality
of the prepared decaffeinated co~fee with respect to its
color, when the adsorption agent, particularly activated
charcoal, is also pre-loaded with an acid. The acid can be
added to the described solution of pre-loading substances or
passed apart fronl the latter in a separate solution. Accept-
able acids are those permitted for foodstuff treatnlent such
as, for example, acetic acid, hydrochloric acid, formic acid,
etc. Preferably, acids are used which are contained in
10 coffee in the natural state. The concentration of acid in
the solution may vary fronl about 0.5% to about 3% by weight.
Subsequent to the acid treatment, the adsorption agent is
rinsed with water.
Adsorption of the Ca~feine
Green or raw coffee is extracted with water or an
agueous liquid and caffeine is adsorbed from the liquid by
means of the pre-loaded adsorption agent. Preferably, a
batch of coffee is nlixed in an extractor with the extracting
liquid and the aqueous extract solution is recirculated
20 through a filter and through one or several adsorption
columns in the circuit until it is free of caffeine.
In order to obtain a high utilization of the adsorp-
tion capacity of the adsorption agent, it is preferable to
employ two or more adsorption columns. For each batch, the
extract solution from the extractor is first passed through
one or several adsorption columns which have been previously
used and then passed through a column with fresh, pre-loaded
adsorption agent. In addition, it is possible to arrange the
~.Z36~
columns in series in the circuit or switch them into the
circuit individually ana sequentially in tinle. At the end
of the adsorption of the caffeine from a batch of extract
solution, the colunln which has been used the longest is
rinsed, emptied, refilled with the adsorption agent and
pre-loaded.
As the liquid for extracting the green or raw
coffee, it is preferred to use a caffeine-free coffee extract
solution whose concentrations of coffee content substances
10 are so high that the solution dissolves substantially only
caffeine. This is achieved d~e to the presence of concen-
trations of other extractable substances in the solution
which are in equilibrium with the concentrations of the
corresponding substances in the coffee beans. This equi-
librium is further maintained since the pre-loaded adsorp-
tion agent adsorbs substantially only caffeine from the
solution. The beans treated in this way must only be sub-
sequently dried prior to further treatment.
In another embodiment of the invention, water is
20 used as the extracting liquid. Suitably used is the rinse
water which is derived from rinsing the adsorption column
which has been in longest use in the adsorption of a preced-
ing batch of extract solution. This rinse water is preferred
since it contains a significant concentration of coffee
extract residues. In this embodiment, there are also extract
substances other than caffeine dissolved out which, after
the adsorption of the caffeine, must again be combined with
the beans. For this purpose, subsequent to the adsorption
procedure, the beans are separated from the extract solution
3L~..Z3656
and dried by means of hot air or under vacuum to a moisture
content ranging between 10 and 40% by weight. The extract
solution is concentrated under a vacuum in a distiller until
the ratio of filled coffee weight (kg.) to concentrated
extract solution (liter) has reached a value between about
5:1 and about 5:4. The concentrated extract solution is then
placed together with the dried beans at a temperature of
between about 40C. and about lOO~C., preferably between
about 60C. and 80C. and adsorbed by the beans. Subsequently,
lO the beans are again dried to the desired moisture content.
Suitable conditions for the described extraction
and adsorption of caffeine are as follows:
Flow rate of the process liquid in the circuit
through extractor and adsorption colunln(s):
5-25 m3/hr.;
Temperature: 40-100C., preferably 70-90C.;
Duration: 6-12 hr.;
Ratio of process liquid quantity (water quantity)
to coffee quantity: 1:1 to 5:1.
The described rinsing of the adsorption column in
longest use can take place after every adsorption cycle as
follows: rinsing one or more tin~es with water, to which
acids of the type also used for pre-loading can be added
if necessary. If available, the condensate from the
described distillation of the extract solution may be used
as the rinse water in lieu of or in addition to fresh water.
Preferably, the rinse water is pumped fronl a heated rinse
water tank in the circuit and through the adsorption colunln
taken out of operation. Rinse water teniperatures generally
~.Z3~
range from about 50C. to about 100C., flow rates fronl
about 5 to about 25 nl3/hr. and rinse periods from about .5
to about 2 hours. The rinse water may be used afterward as
the extracting liquid for the next batch as has been pre-
viously described.
According to the present invention, a satisfactory
roàstable caffeine-free raw coffee is obtained having a
bright color and with a good cup quality. The coffee has an
extract content of nlore than 22~ and a caffeine content of
10 less than 0.1~ (after roasting).
Example
In a pre-loading tank with a 2500 liter capacityr
2000 liters of water, 50 kg. of cane sugar and 10 kg. of
formic acid (99/100~) are niixed and heated to 80C. This
solution is passed for a period of 10 hours in the circuit
through an activated charcoal column having 500 kg. of
activated charcoal. The rate of flow is 10 m3/hr. Follow-
ing this, the solution is pumped back into the pre-loading
tank. The activated charcoal is then rinsed with 1000
20 liters of cold fresh water.
In an extractor with a 9000 liter capacity, 2500
kg. of raw coffee and 7000 liters of water are mixed. The
liquid or extract solution is pumped through a filter at
70C. and 15 m3/hr. in the circuit through the pre-loaded
activated charcoal column. After eight hours, the extract
solution is practically caffeine-free. The total aqueous
extract solution is placed in a distiller and concentrated
--1 0--
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under a vacuunl to 1000 liters. ~he beans are dried by hot air
to 30% moisture content. Subsequently, the concentrated
extract solution and the dried beans are placed together in
the extractor. The beans completely absorb the entire extract
solution at 75C. within three hours. The beans are then
dried by hot air to a moisture content of 10%.
The column taken out of operation is rinsed three
times, each time using 2000 liters of condensate of the
distillation or fresh water which additionally contains 2-4
10 kg. of formic acid (99/100%~. The column is rinsed at 90C.
each tinle for 90 n~inutes, using a rinsing tank-to-column-
to-rinsing tank circuit. The rinsing water is collected and
used as extracting water for the following batch.
The extract content and the coffee content of the
untreated raw coffee and the treated caffeine-free raw
coffee were measured each time after roasting according to
the regulations of the Swiss foodstuffs law. The untreated
coffee contains after roasting 28~ extract substances and
1.3~ caffeine. The same coffee, treated in accordance with
20 the present invention, contains after roasting 2305~ extract
substances and 0.04~ caffeine.
- As may be seen fronl the above description and
specific example, raw coffee that is treated in accordance
with the present invention may be further processed to yield
a product that contains substantially all of the originally
present extract substances, but which is substantially
caffeine free.
Although the invention has been described with
preferred embodiments, it is to be understood that variations
~.236~i6
and modifications nlay be resorted to as will be apparent to
those skilled in the art. For example, although the process
. has been described on a batch basis, it may likewise be
perfornled on a semi-continuous or continuous basis. These
variations and modifications are to be considered within the
~: scope of the following claims.
.~,
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