Note: Descriptions are shown in the official language in which they were submitted.
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Description
The invention relates to a process for producing
coffee extract by extraction from roasted and broken
coffee beans
Various processes for producing instant coffee are
known Conventional-y, the coffee beans to be extracted
are roasted, ground or broken and extracted, whereupon
the extract obtained is concentrated and dried.
During extraction, it is possible to carry out van-
ion aqueous extraction stages. Thus, for example, it is
possible, by jeans of the extraction of the broken roast
coffee firs to obtain in a percolator with hot water a
primary extract which has a partaker high proportion
of aromatic substances typical of roast coffee. Sub-
sequent, the extracted coffee beans con be-treated further
with process water in one or Gore further extraction
stages, to obtain a suckled secondary extract.
In known extraction processes for obtaining coffee
extract, the Avery is often unsatisfactory. To achieve
an improvement in this respect, various processes have
been developed to tree extract or part extracts of sub-
stances having an unpleasant taste.
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It is also already known to dray off aroma fractions
by means of steam distillation The aromatic substances
obtained in this Jay are moreover added to the extract
again, after the extraction of the roast coffee to improve
the aroma.
The object on which the invention is based is to
propose a process for producing coffee extract by means
of which products having improved flavor properties can
be obtained in an economically favorable Jay.
To achieve this object it is proposed, according
to the invention that the roast coffee retaining after
the separation of the extract fraction in a primary hot-
water extract10n stage should undergo a secondary hot-
water extraction, and that the secondary extract obtained
thereby should be treated with a weakly basic ion exchanger.
treatment of the secondary extract with ion ox-
changers of the weakly basic type results in a surprise
tingly naked improvement in the flavor of the coffee ox-
tract, when the secondary extract treated in the Jay actor
ding to the invention is also used. because the Jon ox-
changer is used, on the one hand the pi value of the ox-
tract it changed, in particular increased. This in con-
junction with the primary extract and, if appropriate,
the aro~atie substances extracted by means of previous
steam distillation, results in an altogether Gore favor-
able pi value of the coffee extract It is important
here, to realize that the secondary extract contains acids
which exert an adverse effect on the flavor of the coffee
extract ("undesirable acids"). In contrast to this, the
primary extract contains acids advantageous for fever
formation Chine assiduous. Accordingly, a feature of the
process according to the invention is that the undesirable
acids of the secondary extract are reduced effectively in
terns of fever.
furthermore the surprisingly favorable effect of
the treatment of the secondary extract with (weekly basic
ion exchangers is obviously also based on the adsorption
effect of the ion exchanger as regards non identifiable
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substances which Likewise exert an adverse effect on the
flavor formation of the coffee extract. the interaction
ox the increase in the pi value and the adsorption of
substances of unpleasant taste results in the surprising
improvement in flyover
The result of the improvement in flavor of coffee
extract, achieved by jeans of the invention, can be add-
itionaLLy increased if roast coffee beans treated accord-
no to the short-time roasting process are used. During
short-time roasting by means of known processes or in
known roasting machines with roasting times of preferably
1 to 3 minutes, roast coffee with a higher proportion of
aromatic and extraction substances is obtained Assay
thy proportion of "fine acids" desirable US regards flay-
our is higher than in "normally roasted" coffee.
In a preferred exemplary embodiment of the process
according to the invention, the roasted coffee beans are
broken in a conventional Jay, in particular with a degree
so grinding to obtain a grain size of 3~5 mm. The broken
roast coffee can no be subjected directly to subsequent
hotter extraction. before this extraction, it is
possible to remove from the roast coffee in a known or
suitable Jay aromatic substances Shea are not exposed to
extraction and concentration so as to protect them, but
which are added to the extract again after these process
steps hayed been carried out. The aromatic substances can
be separated, in particular, by means of steam distill-
lion Preferably, this steam distillation is carried out
at such a pressure that the treatment temperature is below
1 00C . ............................................. ...
A flow diagram attached hereto illustrious the
course of the preferred exemplary embodiment of the
process.
Steam distillation of the roast coffee is carried
out in a percolator En. The distillate obtained by
means of vacuum treatment and subsequent condensation is
combined with the remaining extracts after the Latter
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have been concentrated.
The roast coffee treated, for example, according to
the above process is extracted with hot water in a separate
extraction circuit (percolators En .. Hi). A suckled
primary extract with a high proportion of aromatic sub-
stances and "fine acids" is obtained thereby. Extraction
takes place in a conventional solid-extraction device
which can be operated with water at increased temperatures.
For example, a percolator is suitable for this purpose.
The process water is heated and conveyed through the per-
collators En I. Hi, and the primary extract (PI) obtained
is combined with a secondary extract (SEX, obtained and
treated in the way described below, before concentration
of the aqueous extras Primary extraction takes place
at relatively lo temperatures up to approximately 130C,
preferably at approximately 100C.
After the aqueous primary extract obtained this
Jay has been drawn off, the roast coffee remains in the
extraction vessel and undergoes secondary extraction in
this vessel percolators En .. Eye). This is Likewise
carried out with water at temperatures of between 130C and
200C, preferably at approximately 170C.
As is evident from the "flow diagram", secondary
extraction is advantageously carried out with several
percolators En .. Eye being connected in series, the
process water being conveyed through these. This water
flows into the percolator Eye containing the roast coffee
previously subjected to primary extraction The pyrrhic
later En with the highest degree of extraction is removed,
emptied and prepared for a new extraction operation as
soon as a following percolator assumes the position of
the percolator Eye, after primary extraction has been
carried out. In this Jay, a maximum quantity of secondary
extract USE) is removed from the roast coffee.
The secondary extract USE) is then passed through an
ion exchanger It of the weakly basic type. This causes,
on the one hand, an increase in the pi value of the sea-
ondary extract. The pi value of this can be in the range
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between 4 and 5, for example around 4.5, and can be
increased by the ion exchanger (IA) to 6 to 7, in particular
to 6.5. Furthermore, not yet identified substances which
obviously have an adverse effect on the flavor of the
coffee extract are bound by the ion exchanger (IA). Because
of the adsorption effect and the influence exerted on the pi
value of the secondary extract, a marked and surprising
improvement in the flavor of the coffee extract is achieved.
The ion exchanger of the type of a weakly basic
anion exchanger, particularly in the OH form, can be micro-
porous or macro porous. Weakly basic anion exchangers on a
polystyrene basis in powder form or as granules (small beads)
are particularly suitable. Furthermore, preferably a pro-
portion (for example 9%) of divinylbenzene is added to the
ion exchanger for cross-linking purposes. Ion exchangers of
type II of Messrs. Merck and ion exchangers "LIGHTWEIGHT" MY 62
of Messrs. Bayer A have proved especially advantageous.
The secondary extract is preferably treated in the
ion exchanger in batches. The extract with a pi value of,
for example, 4.5 is passed through the ion exchanger and
collected in a vessel on the outlet side. At the same time,
the pi value of the treated extract is measured continuously.
This gradually decreases starting from a relatively high
value. As soon as a pi value of the desired order of
magnitude of, for example, 6.5 is obtained, treatment is
suspended.
Treatment in the ion exchanger can also take place
continuously. The quantity of the weakly basic ion exchanger,
the flow rate or the contact or residence time of the extract
in the ion exchanger and the temperature influence the pi
value of the treated solution. The above data must be
selected so that the desired increase in the pi value for
the secondary extract is obtained. The treatment temperature
is approximately room temperature or below this. When the
temperature is lowered, although the reaction rate is reduced,
nevertheless the adsorption capacity of the ion exchanger
* "LIGHTWEIGHT" is a trade mark
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is improved.
After a batch of the secondary extract has passed
through the ion exchanger, or after several passes
through it, the latter is regenerated. For this purpose
the ion exchanger is first flushed with awry. It is then
treated for example with caustic soda. Renewed flushing
with water is subsequently carried out The above men-
toned cleansing of the ion exchanger preferably takes
place at an elevated temperature of, for example, 40C
to ~0C~
The secondary extract treated in the Jay desk
cried above, namely a clear brown liquid, is combined with
the primary extract and concentrated, for example in convent
Sheehan evaporators. The distillate which, if appropriate,
was obtained at the outset by means of vacuum extraction is
then added to the concentrate. The total My xture can then
b? dried in the conventional Jay, for example in a con
ventional spray-drying or freeze-drying process.
Thy process described above, including short-~ime
roasting, is i~ustrated in the "bock diagram" attached
hereto. Furthermore, steam distillation for separating
aromatic substances before the extraction process is used
there.
The coffee extract obtained by the process accord-
in to the invention contains a marked aroma improvement,
even though the secondary extract is also used. Because
of the processing of the secondary extract, the economic
efficiency of the process is guaranteed, since a higher
yield of roast coffee is obtained, whilst at the same
time disadvantages in terms of flavor are avoided.
The following examples serve to explain the in-
ventionD Example 1 showing results when "normally" roasted
unprocessed coffee is used and Example 2 showing results
based on unprocessed coffee roasted for a short time.
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Example _
1. Unprocessed coffee mixture
Components: Ethiopian mocha 20%
Cantos 25%
Guatemala 15~
Ivory Coast 20%
Cameron 20%
2. Roasting longtime roasting)
PROBATE batch roaster
Color value 11
Roasting time 11 mix 55 sea
Gas pressure 61 mulberries
m roast coffee 5 kg
Total quantity of roast coffee 20 kg
3. Grinding
"BUHLER-MIAG" grinding unit (Technicum)
Gap widths at the top 3.4 mm
at the bottom 2.4 mm
Bulk density s 308 gloaters
Grain size d50 3.1 mm
4. Vacuum stripping
I: Technicum system
Weighed quantity of roast coffee 4000 g
Pressure 100 mulberries
ED quantity 500 g (steam disk
Strip factor - = 0 125
m roast coffee
* "Prohibit and "BUHLER-MIAG" are trade marks
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Split-up extraction
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Pilot system
Primary extract, quantity of roast coffee 1.9 kg
process water temperature at inflow ~100 C
pressure 10 bar
rate 60 l/h
outlet quantity 30 kg
solids 1.31%
yield 20.7%
pi 5.10
Secondary extract, quantity of roast coffee 1.9 kg
process water temperature at inflow 170C
pressure 17 bar
rate 60 l/h
outlet quantity 29.5 kg
solids 1.18%
yield 18.3%
pi 4.5
6. Separate on
*
"WISTFUL" separator
: Flow rate ~100 l/h
before separation - dry matter 1.17%
pi 4.58
after separation - dry matter 1.10%
- pi 4.59
Dry-matter loss 6%
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* 'iWESTFALIA" is a trade mark
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g
7. Ion exchanger treatment
Pilot system
Column volume = ion exchanger volume = 4 liters = 2 kg
Merck type II ion exchanger, weakly basic anion
exchanger
Process parameters: Temperature = room temperature
Flow rate of extract 30 l/h
Total quantity of extract 40 liters
Specific load 7.5 l/h
extract per lithe of If
Extract before treatment -pi 4.59
-dry matter 1.10%
Extract after treatment -pi 6.55
-dry matter 1.00%
Dry-substance loss 9%
8. Mixing of the primary and secondary extracts in the
ratio of the quantities obtained during extraction.
9. Concentration
"CENTRITHERM"
Parameters: Heating steam temperature 65 C
Evaporation pressure 75 mulberry
Evaporation temperature 38C
Extract feed rate 30 1/h
pi 5.46
dry matter 20%
10. Inoculation
of the extract with SD vacuum
inoculation quantity = 100%
pi 5.41
* "CENTRITHERM" is a trade mark
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ho _reeze-drying
Pilot system G 06
Parameters: condenser temperature -43 C
condenser pressure 0.47 mulberry
hot-plate temperature 35C
total drying time 3 hours
Exempt _
1. Unproces Ed coffee mixture
Components: Ethiopian mocha 20~
Cantos 25%
Guatemala 15%
Ivory Coast 20%
Cameron 20%
2. Roasting
Jettison batch roaster
Color value 11
Roasting time 90 seconds
Temperature 308 C
A 11.3 mulberry
m roast coffee 400 g
Total quantity of roast coffee 20 kg
3. Grinding
"BUHLER-MIAG" grinding unit (Technicum)
Gap widths at the top 3.4 mm
at the bottom 2.4 mm
Bulk density s = 264 g/l
Grain size d50 = 3.1 mm
* "BUHLER-MIAG" is a trade mark
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4 Vacuum strip
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Technicum system
Weighed quantity of roast coffee 3,500 g
Pressure 100 mulberry
SD quantity 437.5 g
Strip factor _ m SD = 0.125
m roast coffee
Split-up extraction
Pilot system
Primary extract: - quantity of roast coffee 1.87 kg
- process water temperature at
inlet 100C
- process water pressure 10 bar
- process water rate 60 l/h
(rate pumped through)
- outlet quantity 30 kg
- solids 1.52%
- yield 24.4% (relative to the
initial quantity).
- pi 4.98
Secondary extract:- quantity of roast coffee 1.87 kg
- process water temperature at
, inlet 170C
; - process water pressure 17 bars
- process water rate 60 l/h
- outlet quantity 27.5 kg
- solids 1.33%
- - yield 19.5%
- pi 4.4
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6. ion
Wistful separator
Flow rate 100 l/h
before separation - dry matter 1.32X
- pi 1~38
after separation - dry matter 1~30%
- pi 4~38
7 Ion exchanger treatment
Pivot system
Column volume = ion exchanger volume = 4 liters = 2 K6
Merck Type II ion exchanger, weakly basic Zion
exchanger
Process parameters: Temperature = room temperature
Flow rate of extract
30 to 35 L/h
Total quantity of extract = 40 liters
Specific load z 7 / 9 l/h of
extract per Hire of If
Extraction before treatment - pi 4.38
- dry matter 1.30X
Extraction after treatment pi 6.54
- dry matter 1.20X
Dry-matter Loss 8X
; I Mixing of the primary and secondary extracts in the
ratio of the quantities obtained during extraction
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Concentration
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Centritherm
Parameters: heating steam temperature 65C
evaporation pressure 75 mulberry
evaporation temperature 38C
extract feed rate 30 l/h
pi 5~34
dry tatter Z7Z
10. Incaution
of the extract with SD vacuum
inoculation quantity = 10û%
pi 5.Z9
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Pilot system G 06
Parameters: condenser temperature -43C
condenser pressure 0.47 mulberry
hot-plate temperature 35C
total drying time 6 hours
In the accompanying drawings, Figure 1 is a flow
diagram illustrating the process described above, and
Figure issue a schematic diagram of the apparatus which
is used.
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