Improvements in Processes and Apparatus for the Preparation of an Extract of Coffee, and in the Utilisation of the Bye- products.
Year: 1889

page_text: Date of Application, 22nd Feb., 1889
Complete Specification Left, 23rd Dec., 1889-Accepted, 22nd Feb., 1890
PROVISIONAL SPECIFICATION.
Improvements in Processes and Apparatus for the Preparation
of an Extract of Coffee, and in the Utilisation of the Bye-
products.
I, EDWARD SONSTADT, of Church fields, Cheshunt, Herts., Fellow of the Chemical
Society, do hereby declare the nature of this invention to be as follows:-
The main features of the invention consist in making an infusion of coffee in an
apparatus designed to admit the collection of the aroma given off during the digestion;
in evaporating the infusion under conditions admitting of the collection of that less
volatile portion of aroma given off during concentration; in incorporating the dried
or syrupy extract with sugar charged with aroma and aroma-water; and in moulding
such mass in portions of any required form or bulk; also in employing any excess
of coffee aroma obtained over requirements in making the extract, in aromatising
sugar or articles of confectionery; and in utilising the spent coffee.
The apparatus I employ for making an infusion of coffee and collecting the aroma
consists mainly of three parts: a boiler, preferably heated by gas flames, above that
a digester, and then an upright condenser, to which near the top an apparatus is
connected for collection of the more volatile part of the coffee aroma.
The boiler may
conveniently consist of a flask-shaped vessel, to the open neck of which is attached,
or into which is inserted, the lower end of the digester. The latter is preferably a
cylindrical vessel, converging to a neck at its upper end, to which the condenser is
attached, and converging to a small closed base at the lower end. Into this base or
near its side a syphon tube is inserted, furnishing the only communication with the
boiler below. This tube, opening into the digester, is curved upwards outside to
about a third of the height of the latter, and then recurved downwards, and is continued
into the neck of the boiler; thus the steam from the boiler passes through this tube
into the digester in which the coffee to be extracted is placed, and condenses there;
or in the condenser above. The effect of this arrangement is that on lowering or
extinguishing the flame under the boiler, the extract formed in the digester is sucked
down, and on reapplying the flame, steam is again produced to be condensed upon
the coffee as before, until the infusion is again ready to be withdrawn, and so on until
the coffee is extracted as completely as may be desired, without the necessity of
obtaining a dilute solution. I place some folds of muslin at the bottom of the digester,
to prevent coffee grains passing into the syphon tube.
The condenser consists of a long vertical tube, which if of glass, may have bulbs at
intervals into which may be let side tubes of small diameter, bent downwards and
re-entering the tube below, as in a well known laboratory apparatus used in fractional
distillation. If the condenser is of metal, chambers may be made in it, similarly
connected to lower parts of the tube by side tubes. In some cases also the tube,
whether bulbed or chambered or not, may be jacketed, so that it may be kept by a
flow of water through the jacket at any required temperature. The object of the
arrangement is that steam issuing from the digester below may very nearly all
condense in the upright tube, and so flow back as water into the digester. The tube
is closed at top either by a cock or a cork. Near the top of the tube a side tube enters
at an inclination drooping outwards somewhat from the horizontal; this tube enters
at its outer end a receiver, which may be of any convenient form, that of a bulb
apparatus such as is used in the laboratory for absorbing or washing gases being very
suitable. Such receiver, which is designed to receive the small proportion of steam
that is allowed to pass so far, carrying with it the aroma of the coffee, and which is
preferably cooled by ice, communicates at its farther end with a more capacious
receptacle loosely packed with wool or other suitable absorbent substance, by which
the finer and more volatile aroma, not condensing with the water in the first receiver,

page_text: It is
is retained. This last vessel, or last of a series of vessels (for any convenient number
of connected vessels may be used) opens to the air: Cotton wool answers tolerably
well as an absorbent material, but a fine description of Heece wool is better.
preferred that when the flame under the boiler is withdrawn or lowered, as previously
described, in order to suck down the infusion formed in the digester, the cork or cock
at the top of the condensing tube should be simultaneously withdrawn or opened, so
as to obviate a return rush of air, carrying aroma back with it, through the receiver.
For reasons which will appear further on, I prefer to change or empty the small
vessel in which steam carrying the aroma condenses, at least three ar four times in
treatment of a single charge of coffee, preserving each portion separate in a well
closed bottle. The early portions contain the more volatile part of the aroma, although
that collected by the wool as described is the most volatile of all. The aroma condensed
from the steam with water in the receiver, I call aroma-water.
As the coffee in the digester is liable to be forced up in a compact mass by the
steam entering the lower part of the vessel, I prefer to pass a stout wire of nickel or
other suitable metal (which may have prongs attached to its lower end) through one
side of the bung closing the top of the digester and into which the condenser is fixed.
The wire should be capable of up and down movement without letting steam escape.
By thus perforating the mass of coffee, way is made for the steam to pass through.
and at the termination of the operation the coffee may be pushed down, so as to drain
it as well as possible.
About five times the weight of coffee taken in water is usually sufficient to
practically exhaust the coffee in the manner described, and an extract of the strength
thus obtained does not within my experience deposit any notable sediment at or near
its boiling point. It is best to add a portion, say about one-fifth, of the water taken,
to the coffee in the digester before beginning the operation, the remaining water being
in the boiler below. prefer to add a little sugar to the water in the boiler, as I
consider that the quality of the extract is thereby improved. When an extract of
both coffee and chicory is required, a mixture of the two substances may be treated
together in the digester; or the chicory infusion may be obtained separately and added
to that of the coffee.
The hot extract when taken from the boiler may be at once transferred to an
evaporating dish or vessel heated on a water-bath or by steam, to be concentrated:
I prefer to conduct the evaporation in a vessel set in a jacket to which steam is
admitted. I also by preference place a gutter or trough around and at a little distance
from the rim of the evaporating vessel, to receive a funnel-shaped hood placed over
the vessel and set in the trough, into which the water, carrying some of the less volatile
aroma, collecting on the inner sides of the inverted funnel, from the steam off the
extract, flows during evaporation. The hood may be cooled externally by water if
desired. As sooner or later a tenaceous film forms upon the surface of the liquid which
greatly impedes evaporation, I pass a rod of suitable material through the top of the
hood, attached to a handle which can be quickly rotated by hand or otherwise; the
rod has attached to its lower end a horizontal wire or bar carrying wires projecting
into the liquid. When the rod is rotated, the wires readily collect the film into clots.
and so renew the surface of the liquid. I prefer to make the wires touching the liquid
of nickel or silver. The steam escaping from the open top of the hood or funnel may
be conducted to a condenser or to a chimney or disposed of in any convenient way.
The water charged with aroma collecting in the gutter should be run into a vessel that
can be closed, and may be utilised instead of ordinary water, in part or wholly, in
extracting the next charge of coffee. Or it may, as well as any excess over require-
ments of the aroma-water obtained during the digestion of the offer, the fractionally
distilled in a special apparatus, similar to that described for forming the coffee extract.
but in which the digester is omitted. The evaporation of the extract may if desired
be conducted under diminished pressure..
The coffee extract evaporated as described may be prepared for distribution in any
way desired compatible with the preservation of its peculiar qualities. But the method
I prefer is to carry on the evaporation until the extract attains a syrupy consistence

page_text: when it should be quickly scraped. from the vessel by a suitable scoop, preferably of
wood, with silver or silver-plated nickel edge or rim, into a previously warned mortar,
where it is rapidly incorporated with sugar (preferably fine jump sugar) which has
just before been wetted with the least volatile portion of aroma-water taken from the
aroma condensing apparatus previously described. While the extract is yet hot, it is
easily thus incorporated with wet sugar, and as the mass cools, it may be further
mixed with another portion of sugar moistened with the next fraction of aroma-water,
and so on until sugar moistened with the earliest and most delicate portion of the
aroma-water is incorporated, by which time the mass will be nearly cold, and if the
proportions of wet sugar and extract taken have been rightly adjusted, will be in a
semi-soft state, and may be compressed or moulded to any desired shape; as for
instance that of lozenges, which after a little while will set hard, and may be stored
in an air-tight closed vessel. The lozenges may conveniently be made to contain
each, extract equivalent to an ordinary cup of coffee". The proportions of sugar,
aroma-water, and extract, may also be adjusted to give a liquid or semi-liquid product.
But in any case I prefer to use sugar in such proportion as to ensure preservation of
the extract from mould, without the necessity of employing salicylic acid or other
chemicals to preserve a liquid extract.
As regards the materials of which the apparatus may be made, I prefer that the
boiler, digester, and evaporator, should be of nickel, or of nickel or other suitable
metal silver-plated; for small sized vessels however, stoneware, porcelain, or even
glass might be used. The condensing tube and hood to evaporator may be of glass,
stoneware, nickel, or other material practically unattacked by vapour off the coffee
extract.
The wool used to absorb the finest part of the aroma may be treated with liot water
in a close vessel to withdraw the aroma; but I prefer to store the sugar intended for
use with the extract, with the aromatised wool in close vessels. The sugar imbibes the
aroma; and the wool, when exhausted or partially so, may be reused.
I may also apply the aroma collected by the wool; or the aroma-water, in making
articles of confectionery; either by, keeping such articles (such being free from other
odour) in contact with the aromatised wool for some time; or by wetting heated sugar
with, the aroma-water, and moulding to any desired shape as before described.
The spent coffee grounds may be compressed into blocks or bricks and dried for
use as manure. Or the dried coffee grounds may be subjected to destructive
distillation to obtain the usual products yielded by matters of organic origin so
treated.
Dated this 21st day of February 1889
COMPLETE
SPECIFICATION.
Improvements in Processes and Apparatus for the Preparation
of an Extract of Coffee, and in the Utilisation of the Bye-
products.
I; EDWARD SONSTADT, of Churchfields, 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 apparatus employed in making an infusion of coffee and collecting the aroma
consists mainly of a boiler, which may be heated by a gas flame; a digester connected
to the boiler by a syphon tube; and an upright distilling or cohobating tube set in
the cover or neck of the digester, to which are connected vessels for condensing the
small proportion of steam permitted to pass so far, and for containing wool, or other
suitable porous absorptive substance, for retaining the more volatile portion of the
aroma which passes off during the digestion of the coffee. The digester, though
closed at bottoin, may have a continuation fitting into the cover or neck of the boiler,

page_text: or it may be placed apart, but preferably on a higher level. The digester should
widen upwards, and have a conical bottom, preferably with a perforated false-bottom,
below or through which the syphon tube enters, the termination of the tube being
provided with a perforated cap. The syphon tube may pass through the side of the
vessel and be curved first upwards and then downwards; or it may pass upwards
through the cover, and be then so curved as to enter the cover or neck of the boiler,
and the tube is best made in two pieces with a ball and socket joint; but whatever
its form or arrangement, it constitutes the only connection between the boiler and
digester; so that when water is boiled in the boiler, steam may pass into the digester,
where it chiefly condenses; and when the boiling is stayed, the infusion formed in the
digester is sucked back into the boiler, which process is continued until the coffee in
the digester is sufficiently extracted. The boiler may be of any suitable form, but is
preferably a short upright cylinder with flat bottom, and with a cover or manhole
fitted on steam-tight, through which the syphon tube enters; it has an exit tube with
cock at or near the bottom. The cohobating tube set in the cover of the digester,
may have bulbs at intervals, with re-entering side tubes, as commonly used in
apparatus for fractional distillation; or the tube may be plain, in which case it should
have greater length. If desired, part of the digester, (preferably not the bottom),
and the cohobating tube, may be jacketed, so that they may be cooled by water, when
steam is rapidly passed in. The open top of the cohobating tube is closed by a cork
or cock, which is temporarily opened when the infusion is being sucked back, so as not
to draw air through the vessels containing wool. A branch tube enters near the top
of the cohobating or upright tube, connected to one or more small vessels, preferably
cooled, in which a small proportion of steam, say one per cent, or less of the total
water used in making the infusion, is allowed to condense as aroma-water. The rate
of boiling in the boiler and the condensation of steam in the digester and upright tube
are regulated accordingly. The last of the condensing vessels is connected by tubing
to one or more closed cylindrical vessels, packed with wool, preferably fleece wool,
made into yarn, and knitted into pieces of circular form, and the terminal cylinder
has an exit tube of small diameter open to the air. These vessels may be cooled
by ice.
To work the apparatus, freshly rotated and ground coffee is placed in the digester,
(the cover and syphon tube having been first adjusted), through the aperture for
insertion of the upright tube; hot or cold water is added; the upright tube fitted into
a cork or bung is put in place, with its adjuncts; and water placed in the boiler, to
which the syphon tube is adapted, is boiled so that steam may pass into the digester.
A little sugar may be added to the water in the boiler. The total water used need
not exceed, and may be less than, ten times the weight of the coffee to be infused.
The water in the digester is thus boiled by the entering steam, and condensation takes
place in the upright tube, aroma-water and aroma being collected in the aroma-water
and wool receptacles already described. When the boiling has continued a short
time, the boiling is stopped, upon which the infusion formed in the digester flows into
the boiler; boiling is then recommenced, and water is distilled into the condenser, to
be again sucked back, and so on, until the coffee is sufficiently exhausted. I find it
advantageous to keep back part of the total water used, to be run hot into the digester
at suitable times during the process. This may conveniently be effected by connecting
a subsidiary boiler, by a tube with cock, entering the side of the digester near the top.
It is advisable to have a rod working through a stuffing-box in the cover of the
digester, to which arms are attached carrying spikes, which can be used both for
compressing and for perforating the coffee; the compressing to assist in draining the
coffee; and the perforating to admit freer passage for steam, when necessary.
The strong infusion collected in the boiler is run out while hot into an evaporating
dish, with rim or flange and circular trough, over which a hood is set, like an inverted
funnel, so that water condensed on the sides of the hood may flow into the trough,
and be run thence by a suitable tube into a receptacle. The hood is closed at top by
a cork or bung through which a rod carrying an arm or arms with projecting spikes,

page_text: is passed, on suitably moving which the film forming during evaporation may be
displaced. A side tube is also connected to the upper part of the hood for carrying
off steam to a condenser. The hood may be cooled externally by a water-jacket. The
evaporating dish is preferably heated by a steam-jacket. The water condensed from
the steam given off during the evaporation carries some aroma, and is used instead of
water in treating the next charge of coffee.
The boilers, digester, evaporating dish, and connections (except the cohobating tube
and its adjuncts, which may be of glass or earthenware) are preferably made of
nickel, or of copper, nickel-plated within, and a further coating of silver may be given,
especially to the inner surface of the evaporating dish.
When the coffee infusion has been concentrated to a syrupy consistence, it is run
off or removed to a stout nickel-plated mortar or vessel, which may be heated by
direct flame or otherwise until the extract is so far concentrated that a sample will
become hard on cooling. The mortar is fitted with a steam-tight cover having a
stuffing-box through which a rod carrying beaters passes. When the extract is
sufficiently dried, lump sugar that has been kept in close vessels with the wool
aromatised as described, is moistened with the strong aroma-water collected in the
condensers connected to the upright tube belonging to the digester. Such moistened
sugar, with dry aromatised sugar, if required, is added to the extract, and the cover is
fastened on the mortar, which is then heated to about 100° C. and the agitator is
worked until mixture is effected. Should the aroma-water have been taken off by
successive fractions, the latter fractions may be first used, and after partial cooling,
the mortar may be uncovered, and sugar moistened with the early fractions he added,
to be incorporated as before. Another way consists in mixing the aromatised wool in
another similar closed and heated mortar having an agitator, with sugar moistened with
water orwith weak aroma-water(derived from the steam condensed during evaporation),
and then removing the wool pieces while yet warm and plastic, and pressing them
between platens in a closed heated press, to obtain a highly aromatised syrup, of such
consistence as to be solid or nearly so when cold, which may be mixed with the coffee
extract instead of moistened sugar in the manner before described, other portions of
sugar aromatised by wetting with strong aroma-water, and dry sugar, being also
added. Whichever plan is adopted, the proportions of moist and of dry sugar used
should be such as to give with the extract a product that can be moulded to any
desired shape while hot, and that will set when cold. A liquid extract may be made
by dissolving the solid extract in the least possible quantity of water, and bottling up
the same for preservation. But I prefer to issue the extract in the solid state.
When an extract containing both coffee and chicory is required, a mixture of the
two substances may be treated together in the digester; or the chicory infusion may
be obtained separately and added to that of the coffee before or during evaporation of
the coffee infusion.
I may use the sugar aromatised in any of the ways described, in making a coffee
confection, containing the aroma, but without the other coffee constituents.
The spent coffee grounds may be compressed into blocks and dried for use as
manure. Or the dried coffee grounds may be subjected to destructive distillation
in close vessels, to obtain the usual products yielded by similar matters so treated.
In the sheet of explanatory Drawings appended hereto, Fig. 1. represents in vertical
section, the digester, boiler, supplementary boiler, cohobating tube, receiver for con-
densed aroma-water, and the cylinders packed with wool for collecting the aroma.
Fig. 2. is a horizontal section, taken aty, of the digester, showing the arms of the
beater. Fig. 3. shows the evaporating dish and hood in vertical section. Figs. 4. and 5.
show the mortar or mixer in vertical and horizontal sections. Figs. 6. and 7. show the
ress in vertical and horizontal sections.
In Fig. 1, A is the digester, B the boiler, C tlie supplementary boiler; D is the
ohobating tube; E the receiver for condensed aroma-water: F, F, the cylinders
containing wool; and G is a flask open to the air, also containing wool, into which the
ube for passage of any unabsorbed aroma enters. More than one receiver, E; and

page_text: any convenient number of cylinders, F, of any suitable shape, may be used. I do not
confine myself to the form of cohobating tube, D, shown, as any suitable form of
distilling or cohobating column may be used; the cork f may be replaced by a cock,
if desired, which is opened when the liquor is sucked back, from the digester into the
boiler, as previously described. In the digester, A, the syphon tube e, e, with ball
and socket jointh, and rose c', is attached to the grid or perforated plate d, and to the
cover of the digester. The grid rests on the lugs. The coffee is charged in through
the opening e, which is then closed by a bung in which the cohobating tube is set.
The rod, a, sliding in stuffing box, s, and carrying arms, b, b, b and spikes b', can be
partially rotated, so as to reach every part of the charge, except so far as stopped by
the syphon tube, e, as shown in Fig. 2. The manner of working the apparatus has been
already fully described. It will be evident that the relative positions and shapes of the
digester and boilers, the form of the syphon tube, and other subordinate details, may
be modified without departing from the essential features of the invention.
Fig. 3, A, shows the evaporating dish, which may be jacketed to be heated by steam;
or it may be heated by direct flame. The sliding roda, carries arms b, b, and wires 6',
for removing the film formed during evaporation from time to time. The dish has a
trough, d, and outlet tube . for running off into a receptacle, the dilute aroma-
water condensed on the inside of the hood, B. The tube stakes any uncondensed
steam to a condenser.
The mortar or mixer, shown in Figs. 4 and 5, is preferably cast in brass or gun-metal.
and is nickel-plated. The sliding rod w, works in the steam-tight stuffing box s, and
carries agitators, b, b. The infusion concentrated in the evaporating dish,is run hot into
the mixer, A, to which heat is applied, to complete the required concentration, when
aromatised sugar, moistened with aroma-water is added; the cover is fastened on, and
the agitator is used to effect the mixture, the vessel being suitably heated as previously
described.
The press, Figs. 6 and 7, is a strong vessel, resembling the mixer, having instead of
a. sliding rod, a screw a, by which the platens b, b, b, b, are forced down upon inter-
mediate layers of aromatised wool that have been soaked with syrup or with syrupy
extract to exhaust the wool of its aroma. The press is heated during use.
is used to draw off the hot liquid product.
The cock a
Having now particularly described and ascertained the nature of
my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is:-
(1). The apparatus, consisting of a boiler and digester, connected by a syphon tube
as described, in which digester the coffee is treated with water boiled by steam from the
boiler, and in part condensed from such steam, and in which the infusion formed is
sucked back from time to time, simultaneously with the collection of aroma and aroma-
water; also as an adjunct, a supplementary feeder or boiler connected to the upper
part of the digester.
(2). The combination consisting of the cohobating tube connected to the digester,
with its adjuncts, the vessels to condense aroma-water, and the vessels charged with
wool to collect the volatile aroma.
(3). The use of wool or of other suitable porous material for absorbing, the volatile
coffee-aroma in the manner described.
(4). The process for obtaining, with a comparatively small proportion of water, a
strong coffee infusion, simultaneously with the collection of the aroma, in the manner
described.
(5). The use of an evaporating dish, with hood, trough for the collection of weak
aroma-water for use in treating fresh charges of coffee, the instrument: for removing
films, and the tube for carrying off steam, not condensed within the. hood, to a
condenser.
: !.
(6). The described processes for storing the aromatisedwool with sugar for treating. it
in a close heated vessel with moistened, sugar; and for applying sugar so, aromatised in

page_text: the preparation of a confection; or in combination with a highly concentrated or
partially dried infusion of coffee to obtain a solid extract of coffee.
(7). The compression and drying of the spent coffee, or coffee grounds, to obtain a
manure; or the heating of the dried coffee grounds in close vessels to obtain products
of their destructive distillation.