Improvements in Making an Extract of Coffee and a Confection of the same, and in Preserving Liquid Coffee Extracts.
Year: 1890

page_text: Date of Application, 24th Dec., 1890
Complete Specification Left, 24th Sept., 1891-Accepted, 24th Dec.; 1891
PROVISIONAL SPECIFICATION.
Improvements in Making an Extract of Coffee and a Confection of
the same, and in Preserving Liquid Coffee Extracts.
I, EDWARD SONSTADT, of Churchfields, Cheshunt, Herts, Fellow of the
Chemical Society, do hereby declare the nature, of this, invention to be..as
follows:-
The present invention consists of certain improvements upon the *processes and
apparatus for the preparation of an extract of coffee, described in No. 3172,
A.D. 1889.
I have found that-great advantage results by excluding air from the apparatus in
which the digestion of the coffee takes place; as well as from that in which the
concentration of the infusion is effected. This end I attain by passing carbon
dioxide gas or nitrogen through the apparatus, during, or at certain stages of the
process.
.now
In the Specification referred to, the digester is described as having a cohobating
or distilling upright tube or column, closed at top, by a cork or stopper, which is
removed to admit air, when the infusion in the digester is sucked through the
syphon tube into the boiler, on withdrawing the flame from the latter. In
adapt a tube, with cock, to the top of the said cohobating tube,"communicating
with a gasometer or reservoir kept charged with carbon dioxide gas; preferably
over water, and under some pressure-from-the water. When it is desired to suck
back the infusion through the syphon tube into the boiler, the cock is opened
admitting carbon dioxide, the cock leading to the aroma-condensing apparatus
being at the same time closed. The pressure from the gas then assists the action
of the steam-vacuum in the boiler, and maintains an atmosphere of carbon dioxide
in the digester. When the boiler is again heated; to drive steam into the digester,
the carbon dioxide current is shut off, and the cock leading to the aroma-condensing
apparatus is opened. As the steam rises in the digester, the carbon dioxide is
expelled through the aroma-condensing vessels. To the outlet of the last of these
vessels I connect a tube leading to a bottle or vessel containing liquid or solid
extract of coffee from a previous working, which extract absorbs the aroma carried
forward by the gas. The carbon dioxide may, if desired, be passed into the
digester through an inlet specially provided in the cover or side. The apparatus,
after charging with coffee and the necessary.water for beginning the process, may
be filled with carbon dioxide, by passing a current. of the gas through to
expel air.
.
In the evaporating dish described in the Specification named, L.provide an inlet
for a slow. current of carbon dioxide gas to be passed in, the gas passing, off with
the steam to a condenser for the latter.
Nitrogen, or air deprived of oxygen, may be used. instead of carbon dioxide, but
the latter is more convenient.
Another. improvement consists in placing a vessel containing a small portion of
pure, fresh butter, in the series of aroma-condensing vessels, described in the
Specification cited. The butter absorbs a great deal of aroma, and is applied with
sugar in making a pasty or solid coffee extract, or confection.
Another improvement consists in the substitution of recently heated asbestos for
the animal or vegetable wool described in the stated Specification as used in
absorbing coffee-aroma." The' asbestos is a very good absorbent, and when charged
with aroma, may be gently heated, preferably with water, in a suitable retort, and
the aroma; or steam and aroma, given off, conducted into the cooled liquid coffee
extract. Or, when the aroma-charged asbestos is heated with water, a small

page_text: .
proportion distilled off of the latter, carries practically all the aroma with it, and
may be collected in properly cooled recipients, to be stored for use in aromatising
the liquid or solid or pasty coffee extract. The asbestos, thus exhausted of aroma,
is drained, dried, and heated, not necessarily to a red-heat, and is stored while hot
in close vessels for future re-use.
As the preceding improvements on my former process involve some modifi-
cations in the processes for obtaining a liquid, solid, or pasty extract, or confection,
described in the Specification referred to, I will briefly describe the processes
now adopt in the treatment following the infusion.
The infusion obtained as described in No. 3172, A.D. 1889, (subject to the
modifications herein before stated), after concentration in a current of carbon
dioxide gas in the evaporator as already referred to, is run off, if intended for a
liquid extract, at a suitable strength, and is aromatised, not only by being placed
terminally in connection with the aroma-condensing apparatus during the working
of the next coffee charge; and by having distilled into it aroma from aromatised
asbestos; but also, by addition of some of the strong aroma-water collected in
the first receiver or vessel in the series of aroma-condensing vessels, connected to
the digester.
When it is desired to make a pasty or solid extract, the concentration is carried
so far in the evaporator, that the liquid will just flow when hot. It is then run
into the mixer described in No. 3172, A.D. 1889, where it is further concentrated,
either by direct heat or by a steam-jacket. When so far dried, preferably, that it
will set hard on cooling, a little of the aromatised butter, and sugar moistened with
strong aroma-water, and dry sugar, are added in proportion to requirements;
whether a paste or a solid extract is needed. The whole is then worked up by use
of the agitator in the closed, heated mixer, until thoroughly incorporated. After
partial cooling, the mixer is opened, and the contents removed to suitable vessels
for storage or packing; or the mass is moulded under pressure while hot into
convenient forms for use..
In making a coffee confection, larger proportions of aromatised butter and of dry
sugar are added, usually without any moistened sugar.
It is very desirable that a liquid coffee extract should be preserved without use
of antiseptics. To effect this, the liquid when bottled is sterilised by heating once
or oftener to a temperature of about 100° C.; and the corking or stoppering is
made impervious to air, by sealing or other suitable means.
Dated this 22nd day of December 1800
COMPLETE SPECIFICATION.
Improvements in Making an Extract of Coffee and a Confection of
the same, and in Preserving Liquid Coffee Extracts.
1, EDWARD SONSTADT, of Church fields, Cheshunt, Herts., Fellow of the
Chemical Society, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
The present invention consists of certain improvements upon the processes and
apparatus for the preparation of an extract of coffee, described in the Specification
to No. 3172, A.D. 1889, and will be best understood by reference to the accom-
panying drawings in which :-
Figure 1 is a general view showing, as an example, one arrangement of the
apparatus for carrying my invention into practice, the digester in this view being
shown partly in elevation and partly in longitudinal section.
Figure 2 is a transverse section of the digester and
Figure 3 is a section, drawn to a smaller scale than Figures 1 and 2. of the
evaporator.
'

page_text: The roasted and ground coffee is placed in a closed digester A with perforated
false-bottom A'. A tube B connected to a neighbouring vessel or boiler C on a
lower level, passes through the cover A2 of the digester A and the false-bottom A',
below which it terminates in a perforated cap or rose A³. Thus, when water
placed in the boiler C is heated, steam passes into and condenses in the digester A;
and when the source of heat is withdrawn from the boiler C, a steam-vacuum is
formed, which causes suction of the infusion formed in the digester A, so that it
passes into the boiler C. The infusion now in the latter, on being boiled, gives
steam which passes into the digester A, to condense chiefly upon the coffee, and
the liquor so formed may be again sucked back as before, and so on as often as
necessary. A hot-water reservoir, or supplementary boiler D, is connected by a
cock D and tube D2 to the upper part of the digester A, so that hot or boiling
water may be run in whenever needed. An upright cohohating tube E is secured
in the cover A2 of the digester A, and is connected to a series of vessels F F F²
for condensing aroma-water and aroma. These arrangements, and the manner of
working them, are shown and described in the before-cited Specification.
may
enter
One of my present improvements, consists in passing carbon dioxide gas,
preferably produced by acting on marble fragments with sulphuric or hydrochloric
acid, and washed by passage through water, into the digester A. The gas may be
led to the top of the cohobating tube E, by a tube E' with cock E², or
the digester A by a special inlet. When the digester A is charged with coffee,
and water is being heated in the boiler C ready for working, a current of the carbon
dioxide gas is passed into the digester. The gas passes also into the boiler C
through the suction or syphon tube B, and has exit through a vent C' in the cover
of the boiler, which vent, (used also for feeding water into the boiler before
starting) is otherwise kept closed. Air is thus driven out of the digester A and
boiler C, and replaced by the carbon dioxide gas. While the gas is passing, the
cock E leading to the aroma-condensing apparatus F F F is kept closed. Each
time when the infusion formed in the digester A is sucked into the boiler C, the
cock E leading from the gas supply is opened, while the cock E³, connecting to
the aroma-condensing apparatus is closed. Thus, the carbon dioxide gas assists by
whatever pressure may be kept up in the gasometer, or gas-delivery vessel, the flow
of the infusion through the suction tube B into the boiler C. On recommencing
boiling, the current of gas is cut off, and way is opened to the aroma-condensing
apparatus F F¹ F².
Another of the present improvements consists in using a small proportion of fresh
butter in one or more of the aroma-condensing vessels FF1 F2, if a solid or pasty
extract or confection is to be made. Butter may be replaced by a suitable edible
fat or oil, though not advantageously.
as
A further improvement consists in substituting asbestos (or less advantageously,
glass-wool or slag-wool or the like) for the wool used in absorbing aroma
described in the before-cited Specification. The asbestos preferred is that manu-
factured into a form resembling string or rope. It is heated sufficiently before use
to burn away organic matter, and is stored in close vessels until wanted. The
asbestos may be placed in Woulfe's bottles such as For vessels of any other
convenient shape such as F2. for collection of the aroma evolved during the
digestion of the coffee. When charged with aroma, the asbestos may be transferred
to a retort and covered with water or dilute aroma-water, as that obtained from
condensation of the steam given off during concentration of the coffee infusion in.
the evaporator G Fig. 3. On applying heat, preferably through a sand-bath or
ozokerit-bath G', the steam arising from the retort-contents, carrying aroma with
it, is collected in the well-cooled liquid coffee extract, which is thus aromatised.
Or the steam may be condensed in a well-cooled receiver, and the rich aroma-
water obtained, be used to moisten sugar in making a pasty or solid extract; as
hereinafter described. Very little boiling is necessary to carry practically all the
aroma from the asbestos in the retort. The asbestos, after draining, drying, and
heating, not necessarily to redness, is fit for re-use.

page_text: The first vessel F connected to the cohobating tube E of the digester A, is a flask
or other vessel of any convenient form, in which so much steam as is allowed to
reach so far, condenses, forming a rich aroma-water.
To this condenser is
connected a vessel containing butter, when a solid or pasty extract is to be made;
otherwise, this is dispensed with. Then come asbestos-charged vessels F' F* and
more if desired. All the vessels F F F are closed, and suitably connected by
tubes F They are kept cool, as for instance, by being placed, in other vessels
containing ice; or through which cooled water is caused to flow. Sometimes the
asbestos-charged vessels towards the end of the series, receiving least aroma,
instead of being emptied at the end of the working, are placed. first in the series
on the next working, that they may become strongly aromatised. The last
asbestos-charged vessel may be connected to a bottle.H containing concentrated.
coffee infusion, by a tube II dipping into the liquid. Or portions of the solid
extract may be placed in a vessel connected to the aroma-absorbing vessels.
In the before-cited Specification, the digester A and boiler Care represented as
of about equal bulk. I do not confine myself to any special form of vessels..or
relation of bulk; which may be greatly modified without departing from the main
or essential features of the invention. But I prefer a boiler consisting of an
upright cylindrical. vessel, with cock. C2 near the bottom, gauge-tube C³ to show
height of liquor inside, and removable cover C, secured on steam-tight in-any
convenient way: The cover C is furnished with an opening to receive the end of
the suction or syphon-tube B,, which is fitted in air-tight. Another small opening
is provided in the cover, serving for introduction of water or of weak-washings,
from a previous coffee charge, and also for exit of carbon dioxide gas, when- a
current of this is passed through the combined apparatus to expel air the cock C
fulfilling these requirements.. This cock is of course kept closed when, not needed.
for the stated purposes. The digester A. I now prefer to make of much greater.
contents. than the boiler C, but the increase of size is preferably gained by.
lengthening, not deepening. A convenient form, especially when the digester
is made of aluminium, (the most suitable material), is that of a covered trough A
with perforated false-bottom A, placed at a slight: angle to the horizon (which.
angle is not indicated in the drawings); so that the liquor may drain to one end,
at which end the suction or syphon tube B dips to the bottom, is carried through
the cover and connected to the neighbouring boiler C. Such a digester could:
be made by shaping sheet aluminium with a flange A' on each side to receive. the
cover and fastenings; and end-pieces with similar flanges A', joined on by soldering
or melting the edges by the oxy-hydrogen flame. The tube D2 passing from the
supplementary boiler D to deliver hot water on to the coffee-in-the-digester A,
should be prolonged so as nearly to reach the farther end, and be perforated
throughout its length within the digester. With large apparatus, the tube D², as
shown in the accompanying drawings, should have also perforated branches D³ so
as to distribute the water almost uniformly, and to enable the perforated bottom A¹
to be readily lifted out, the tubeches D will, for the time-being be vertical: The
be fitted with a joint D' which admits of
its being turned so that the branches.
cohobating tube: E might be fixed in any convenient part of the cover A², but
preferably at the end opposite that at which the syphon tube B enters. The
digester A. is preferably jacketed as at A' so that it may be cooled externally,
by water when desirable. In a vessel of this form, having much length and little
depth, the compressing and perforating apparatus described in the before-cited
Specification, is not a necessary adjunct.
One great advantage of the form of digester now recommended, is that there.
is no great depth of coffee-grounds, difficultly permeable, as in an upright
conical vessel of similar contents; but the capacity being increased by length
instead of depth; such increase of capacity does not hinder passage of liquor
through the coffee. The supplementary boiler D, intended merely as a hot-water
reservoir for.supplying the digester A as required, may be of any convenient form,
though that of an upright closed.cylinder, with cock D leading to the upper part

page_text: of the digester from near the bottom, and.gauge-tube D', and opening in the
cover closed by a preferably weighted cover D, for introducing water, is very
suitable.
When the digester A is charged with freshly roasted and ground coffee, the
water in the supplementary boiler D being brought to a boil, a little water being put
into the boiler C (enough to get up steam), air being expelled by carbon dioxide
gas as described, and connection being made to the aroma-condensing vessels F F' F',
heat is applied to the boiler C, so that steam passes into the digester A. Boiling
water is then run in from the supplementary boiler D, so as to spray over the
surface, of the coffee. The proportion thus run in, may conveniently be from
twice to four times the weight of coffee in the charge. After continuing the
passage of steam into the digester. A for a few minutes, the flame is withdrawn
from the boiler C, when the infusion formed is sucked into the latter. During the
suction, passage is opened through the cock E2 to the carbon dioxide gas supply,.
and closed through the cock E³ to the aroma-condensing vessels F F F², reversing.
this when boiling is recommenced, which is done when the infusion has all, or
practically all, passed into the boiler C. The boiling is continued, until the
infusion is considerably concentrated, steam being prevented meanwhile from
passing too far (very little being allowed to reach the first condenser F) by suitable
cooling of the digester A. The steam-pressure is then lowered, but not sufficiently
for suction, and all but a little of the concentrated liquor is run off by the cock C²,
and taken at once to the evaporator G. On then removing the flame, the infusion
formed in the digester A is sucked back. Before the suction is completed, more
water may be run in from the reservoir D (supplementary boiler), and the washings
sucked over.
The boiling is then recommenced and the process conducted as before,
the liquor concentrated in the boiler C being each time. transferred to the
evaporator G. The process is continued for a longer or shorter time, according to
the extent to which it may be considered desirable to exhaust the coffee. After
obtaining the last portion of concentrated infusion, which it is considered desirable
to take, a considerable quantity of hot water may be run over the coffee, sucked
into the boiler C and run off for use in the next working, instead of water.
It will be obvious that the described processes of digestion and exhaustion of the
coffee may be modified in many ways without departing from the main lines of the
invention. For instance; the infusion obtained in the first suck-back may be
drawn off and returned to the digester A through an aperture A', ordinarily
closed by a lid A, in the cover A2, and again sucked back, which is easily.
managed. The process may be repeated two or three times, if desired, and the
strong infusion so obtained may be at once, without further treatment, bottled up.
and sterilised as a specially delicate extract. The ordinary process may then be
conducted upon the coffee in the digester to obtain a coarser and cheaper extract.
According to another modification, the suck-backs may be made without first
drawing off the concentrated portion in the boiler C: but this involves waste of fuel
and time, besides requiring a boiler as large, or nearly as large, as the digester A.
The proportion of water used in extracting the coffee may be greatly varied; but
usually five or six parts water (apart from the final washings) used in all with
one part of coffee will give satisfactory results.
Instead of effecting the suction by withdrawal of the source of heat from the
boiler C, some economy may be effected by injecting into the boiler C a very small
quantity of cold water by a spraying tube, the means of doing which do not need
particular description. In such case, the boiler C may be lagged, or packed
externally with some suitable bad conductor of heat, to lessen loss of heat by
radiation.
It has been stated that the coffee infusion is withdrawn from the boiler C from
time to time, as it becomes concentrated therein, to an evaporator G. The form of
evaporator that I prefer is similar to that described in the before-cited Specifica-
tion. As shown in Fig. 3 it is of hemispherical form, with a flange around the

page_text: edge, depressed outwards, and provided with a rim G³, and outlet tube G. A
conical hood or cover G, provided with a cooling water-jacket G, rests upon the
Hange G², close to the rim G³, so that the flange forms a trough or channel G' into
which the water condensed from the steam produced during evaporation, collects,
and flows through the outlet tube Ginto a receptacle. This water of condensation
constitutes a weak aroma-water, and is used in part to replace ordinary water in
treating the next charge of coffee. The evaporator G may be heated by a steam-
jacket G, or a jacket charged with a material of high boiling point, as ozokerit for
instance, heated directly by a flame, may be used. A tube may be provided near
the top of the hood G5 to take off uncondensed steam; but with proper cooling of
the hood G by the water-jacket G, it is unnecessary. The hood G³ should be
provided with an inlet tube G for carbon dioxide gas, a current of which is kept
flowing during the progress of the evaporation, and may have exit by the outlet
tube which conducts away the water of condensation. The apparatus for removing
films from the liquor in the evaporator G, described in the before-cited Specification,
may be dispensed with.
'
If a liquid extract is required, the liquor in the evaporator G, when sufficiently
concentrated, is run into a receptacle, preferably some form of bottle, flask or
carboy, with not too wide a neck, and after cooling, is charged with aroma from
the aromatised asbestos, in the manner already described. The aroma-water
collected in the small condenser F connected to the digester A in the process of
obtaining the coffee infusion, is then added, and the liquid extract, after some
agitation, is put into bottles, which are firmly corked. A portion of the unaroma-
tised extract-may, if desired, be reserved, to be connected to the aroma-condensing
vessels F F F in the next charge worked off, as before described.
As I prefer not to use any antiseptic substance to preserve the liquid coffee
extract, the preservation is effected by sterilisation by heat. The corks being
firmly secured in the bottles by string or otherwise, the bottles containing the liquid
extract are placed in a water-bath or steam-bath where they are slowly heated up
to the boiling point of water, at which temperature they are kept for an hour or
more, though less time may suffice. The bottles are then allowed to cool slowly,
but while yet warm, the fastenings are removed, the corks are cut off flush with
the tops of the bottles, and the corked ends are dipped into any suitable melted
matter which on cooling will solidify and form an air-tight covering. I have found
melted ozokerit to answer the purpose very well, but do not confine myself to the
use of this. It is preferable to dip twice, once into the very hot ozokerit, in order
that it may penetrate a little way into the corks; and a second time in the ozokerit
not very far from solidifying, to give a sufficient coating to the corks. The bottles
charged with extract thus treated and sterilised may be stored for any length of
time without the contents undergoing change.
When a solid extract is to be made, the concentration is carried as far as may be
in the evaporator G, consistently with leaving the liquid fit for pouring while hot.
The thus highly concentrated liquor is run into a mixer, similar to that described
in the before-cited Specification. The mixer is a stout cylindrical vessel, with
closely fitting cover, through a stuffing-box in which a shaft passes carrying arms,
which serve to agitate. the contents. A. valved tube in the cover permits exit of
steam, which may be condensed if desired. The mixer may be heated by direct
heat, or may be jacketed for superheated steam. When the extract is so far con-
centrated in the mixer that a sample becomes hard on cooling, sugar, some of which
is moistened with rich aroma-water, is added. For a paste, more moistened sugar
is used for a solid extract or confection, much dry sugar with some moistened
sugar and the aromatised butter, are used. In either case, after the addition, the
cover is secured on, and the properly heated mass is worked up thoroughly by use
of the agitator. The product, while yet hot, may be removed, moulded when
desired, and stored in closed bottles or vessels. The "rich aroma-water
"referred
to may either be that collected in the small condenser F connected to the digester A,
;

page_text: in the process of obtaining the coffee infusion; or it may be obtained from the
aromatised asbestos by distilling the latter with water, and collecting the first
portion that comes over in a cooled receiver.
As the object to be attained in the use of carbon dioxide gas in the processes of
digestion and of concentration described, is exclusion of air, the same object may
be attained by the use of nitrogen or of, air deprived of oxygen. But the carbon
dioxide gas is more convenient.
When an extract of coffee containing chicory is required, the two roasted and
ground substances are preferably treated together in the digester A, in the manner
described for coffee only.
It will be obvious that a series of digesters A may be worked side by side, in
connection with one or mere boilers C of suitable relative size, and with one or more
sets of aroma-condensing vessels F F¹ F2.
The digester, boiler, and mixer, are preferably made of aluminium. If made of
other metal, they should be silver-plated internally. The syphon tube B should be
of silver or aluminium.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
(1). The use of carbon dioxide gas or of nitrogen in the apparatus for the
digestion of coffee, and for the concentration of the coffee infusion, in the manner
described.
(2). The use of butter or its equivalent during the process of digestion of the
coffee, as an aroma-absorbing body, and its application in the preparation of a solid
or pasty coffee extract, substantially in the manner described.
(3). The use of asbestos or its equivalent during the process of digestion of the
coffee, as an aroma-absorbing body and the recovery of the aroma from the same,
for application in making a liquid or solid extract or confection, substantially in
the manner described, so that the asbestos is readily made available for re-use.
(4). The use of a long digester such as A of little relative height, admitting
ready percolation through the charge of coffee, in conjunction with a boiler such
as C of approximately similar height but much less contents, from which the liquor
is (preferably) withdrawn from time to time after concentration within the boiler,
substantially in the manner described; such apparatus being used conjointly with a
hot-water reservoir or supplementary boiler D and with aroma-collecting vessels
such as F F F substantially as shown in the accompanying drawings.
(5). The aromatisation of coffee extracts, whether intended for making liquid,
pasty, or solid coffee extracts, obtained by processes described herein, or in the
before-cited Specification of my former invention; and the preservation of the
liquid extract by sterilisation, all substantially in the manner described.
Dated this 24th day of September 1891.
E. SONSTADT.