Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Case 2917
DESCRIPTXON
DE~AFFEINATION OF' A (,OFFEE EXTRACT
05 Technical ield
The present inven-tion relates to a process for
decaffeina-ting aqueous coffee extracts. More particu-
larly, the process involves con-tacting the coffee
extract with a fatty solvent while concurrently
vacuum dis-tilling a portion of the water initially
present from the aqueous coffee extract. The
caffeine-containing fatty solvent is subsequently
separated ~rom the decaffeinated coffee extract.
Background Art
One well-~nown method of decaffeination is
disclosed in U.S. Pat. No. 2,309,029 -to Berry et al.
wherein caffeine is extracted from green cof~ee
beans by con-tact with an agueou~ ex-tract of green
coffee solubles. The caffeine-laden solution is
stripped of caffeine by subsequent contact with a
halogenated organic solvent such as meth~lene chloride.
Another predominant decaffeination method involves
contacting the green coffee beans directly with a
halogenated organic solvent as described in U.S.
Pat. No. 3,671,263 -to Patel e-t al.
The industry has long desired -to eliminate
contact of such halogena-ted organic solvents with
ei-ther the coffee beans or an extract directly
contacting the coffee. Recent disclosures describe
processes using caffeine adsorbents for removing the
caffeine from a solution of gxeen coffee solubles.
For instance, it has been proposed to use
a trea-ted activated
05 carbon as the caffeine adsorbent. A polymeric resin
caffeine adsorbent is disclosed in U.S. Pat. No.
4,031,251 to Margolis. While bo-th types of adsorbents
might be somewhat effective, they are not without
certain drawbacks, SUCh as the inability to
efficiently recover the caffeine rernoved from the
coffee extract.
~ nother approach to elimina-ting the use of
halogenated organic solvents in a decaffeination
process is disclosed in U.~C. Pat. No. 1,516,208
wherein a liquid water-immiscible fatty material is
used to recover caffeine from a vegetable extract.
The solubility of caffeine in the fatty materials
disclosed therein is generally low, indicating the
relative inefficiency of such a process. An
improvement to the process described in U.K. Pat.
No. 1,516,208 is disclosed in U.K. Pa-t. No. 1,532,547
wherein a method of recovering caffeine from the
fatty material subsequent to decaffeina-tion of the
extract is described. The improvement does not
relate to the decaffeination portion of the operation.
It is an object of the present invention to
provide a decaffeination process that does not
involve the use of a halogenated organic solvent.
It is a further object of the present invention
to provide a decaffeination process using a fatty
solvent, which process is more efficient than
processes heretofore disclosed by the art.
Disclosure of -the Inven-tion
I-t has now been discovered -tha-t the objects of
the presen-t in~en-tion are me-t by a decaffeina-tion
process which involves contac-ting a coffee extract
05 with a ~atty solvent while concurrently vacuum
distilling a portion of the wa-ter ini-tially present
from -the aqueous coffee extract. The decaffeinated
coffee extrac-t is subse~uently separated from the
caffeine-rich fatty solven-t, which solvent may be
-treated and returned -to -the process as essentially
fresh fatty solvent.
The term "fatty solvent" is intended to refer
to those fat-ty solvents which are immiscible in an
aqueous coffee ex-trac-t and which solven-ts are
recognized as safe for food processing. A -typical
vegetable oil such as corn oil, soybean oil,
cottonseed oil or safflower oil is suitable. So
too, deodorized and clarified coffee oil is sui-table
for meeting the objects of the presen-t inven-tion.
Coffee oil has -the advantage of being derived from
coffee whereas the other oils derive from other
vegetable sources or perhaps even animal sources.
As hereinabove mentioned, vacuum distillation
o~ the aqueous coffee e~-tract is concurrent to the
contact of said extract and the fatty solvent. It
has been found tha-t -the distillation should be
carried out at a pressure less than 500 mm Hg, with
a pressure less -than 250 mm Hg being particularly
convenient. The -tempera-ture at which -the contact
and concurren-t distillation take place is fixed by
the pressure selec-ted, wi-th a higher temperature
being re~uired when a pressure -towards the upper
limit is used. It is preferable to opera-te the
process at as low a pressure as practical, correspond-
ing to a relatively lower temperature, because -the
efficiency of the present invention is greatly
improved a-t such temperatures. The increased
efficiency resul-ts from the lesser solubility of
caffeine in water a-t decreased temperature.
05 There is some flexibility in selecting -the
level of vacuum distillation to which -the coffee
extract is subject. The greates-t efficiency is
achieved if said ex-tract is distilled from about 25%
by weight coffee solids initially to about 90% by
weight coffee solids; this is particularly true
where the temperature is greater than 50~. At
relatively lower temperatures (which require
suitably low pressures), it may be possible -to subject
the coffee extract to less vacuum distillation yet
still achieve -the same efficiency of decaffeina-tion.
The aqueous coffee extract may be contacted
with the fatty solvent in any vessel which both
provides for liquid-liquid contact and is capable of
maintaining a reduced pressure. A batch-wise scheme
wherein the two components are contacted in a sealed
vessel under a vacuum is one possibility. So too,
the coffee ex-tract and fatty solvent may be contacted
in a continuous liquid-liquid column, which column
operates under a vacuum and is capable of the heat
input necessary for the concurrent vacuum distillation
of the ex-tract. The temperature and pressure at
which said contact takes place are the values selected
for -the concurrent vacuum distilla-tion.
A major advantage of the present invention is
the efficiency of -the decaffeination as reflected by
the ratio of the weight of fatty solvent con-tacted
to the weight of aqueous coffee extract decaffeinated.
It is desirable to minimize the amount of fatty
solvent used and the size of the equipmen-t required
for carrying out the invention. In a departure from
pr:ior art, it has been found tha-t grea-ter -than 90%
by weigh-t decaffeina-tion of an aqueous coffee extract
may be achieved with a weigh-t ratio of approxima-tely
15 gm of fat-ty solven-t/gm of aqueous ex-tract (initial
05 concen-tration is 25% by weight coffee solids3.
Manipulation oE said ra-tio in the present invention
will provide a grea-ter degree of decaffeina~tion as
desired.
Under certain circumstances, it may be more
convenient to operate this invention in stage-wise
fashion to achieve the required level of decaffein-
ation. The preferred stage-wise scheme is to contact
the fatty solvent with the coffee extract while
concurrently vacuum distilling said extrac-t from
about 25% by weight coffee solids -to about 90% by
weight solids. The concen-tra-ted partially decaf-
feinated coffee extract is diluted -to aboll-t 25% by
weight coffee solids and contacted wi-th fresh fatty
solvent in the nex-t stage. The water used for
diluting the partially decaffeinated coffee e~-tract
is preferably the condensed water collected during
the vacuum distillation of the previous stage.
Though other stage wise schemes may he used, the one
disclosed herein is preferred because i-t provides
for concurrent contact of the components and vacuum
distillation in each stage. The value of the vacuum
distillation in each s-tage lies in the increasing
concentration of caffeine in -the coffee extrac-t as
water is distilled therefrom. Caffeine is -transferred
to the fatty solven-t in order to establish a new
equilibrium as said concentration increases in the
distilling coffee extract.
Once -there has been sufficient con-tact and
vacuum distillation by batch-wise, stage-wise or
continuous operation, the caffeine-con-taining fatty
-- 6
solvent is separa-ted from the decaffeina-ted coffee
extract. The coffee extract at about 90% by weight
coffee solids is diluted -to between 20% by weight
and 40% by weight solids and returned to the coffee
05 process. Caffeine may be removed from -the fat-ty
solvent by vacuum steam stripping as disclosed in
U.K. Pat. No. l,532,547, or -the caffeine may be
recovered by simple water washing. The essentially
caffeine-free fat-ty solvent is then re-cycled back
to -the decaffeination operation.
The present inven-tion may be used -to decaffeinate
an extract of green or roasted coffee. A green coffee
extract decaffeinated by the present invention may
preferably be one as is used in -the Berry et al.
disclosure hereinbefore discussed. It may also be
desirable to decaffeinate a roasted coffee ex-tract
during the processing of the extract into a decaffein-
ated soluble coffee. In view of the vacuum dis-
tillation though, it is preferable -to s-trip the
flavor and aroma constituents from such a roasted
coffee extract prior to decaffeina-tion. Said aroma
and flavor constituents may -then be returned to the
decaffeinated coffee extract.
est Mode For Carrying Out The Invention
The following examples are intended to demonstrate
certain embodiments of the present invention. The
examples are not meant to limit the inven-tion beyond
what is claimed below~
Example 1
1. 200 gm of green coffee extract (.57% by
weight caffeine and about 25% by weight coffee
solids) were mixed with 1000 gm of partially hydrogen-
ated and winterized soybean oil (sold under the
brand name of Wesson*Oil~.
* Trade mark
2. The mixture was placed in a Ro-to Film
~vaporator (supplied by Ar-thur F. Smith Co. of
Rochester, N.Y.) at a pressure of about 230 mm ~Ig
and a tempera-ture between 70C and 75C un-til about
05 90% by weigh-t of the water initially present had
been distilled from the coffee extrac-t, this -taking
about -two hours. The evolving water was collec-ted
as a distillate.
3. The components were allowed -to separate
and were then separately decanted off. Small samples
of the edible oil and coffee extrac-t were re-tained
for analysis.
~ . The green coffee ex-trac-t was diluted to a
concentra-tion of about 25% by weight coffee solids,
lS using the distillate collected from S-tep 2.
5. Steps 1-4 were repeated twice more, using
1000 gm of fresh edible oil for each stage. The
results are sul~marized in the table below.
Table
20 Sta~e % Overall Decaffeination
1 61.3
2 86.5
3 91.8
Example 2
Roasted coffee extract (2.9% by weight caffeine
and 20.0% by weight coffee solids) was con-tacted
with partially hydrogenated soybean oil (sold under
the brand name of Wesson Oil) at a weight ratio of
50 oil/l coffee extract. The two liquids were
contacted under moderate agitation a-t 80C for a
period of 45 minutes and -then separated for analysis.
Only 45% by weight decaffeination of -the coffee
extract was achieved.
This example demonstrates the value of the
concurrent vacuum dis-tilla-tlon step. Here, in excess
of 3 -times the amount of oil was used but the level
of decaffeination was only abou-t half that of Example 1.
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