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

page_text: Date of Application, 27th Dec., 1890
Complete Specification Left, 24th Sept., 1891-Accepted, 24th Dec., 1891
PROVISIONAL SPECIFICATION.
Improvements in Making an Extract of Tea and a Confection of the
same, and in Preserving Liquid Tea 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 tea, described in No. 20,182,
A.D. 1889.
I have found that great advantage results by excluding air from the apparatus
in which the digestion of the tea 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.
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. I now
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 tea 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 tea 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, I 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 good deal of aroma, and is applied with
sugar in making a pasty or solid tea 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 tea-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 tea
extract. Or, when the aroma-charged asbestos is heated with water, a small
. 017

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 tea 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.
Hops may, if desired, be added in small proportion to the tea infused in the
digester. But if this is done, I prefer, in the subsequent process of concentration
of the infusion, to evaporate the liquor to a pasty consistence, and then to dissolve
the product in hot water, and filter while hot. The filtrate may then be con-
centrated, and treated in any of the ways hereinafter indicated, to obtain a liquid,
pasty, or solid extract. Even when hops are not added, a clearer extract is
obtained by adopting the above process, though it is attended with some loss of
caffeine.
As the preceding improvements on my former process involve some modifications
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 I
now adopt in the treatment following the obtainment of a tea infusion.
The infusion obtained as described in No. 20,182, 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 tea 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. 20,182, 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 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 con-
venient forms for use. In making a tea confection, larger proportions of aroma-
tised butter and of dry sugar are added, usually without any moistened sugar.
It is very desirable that a liquid tea 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. But I prefer to use the
process of sterilising and stoppering described in the Specification of an invention
for which I have applied for provisional protection, namely, No. 20,411, A.D. 1890.
Dated this 23rd day of December 1800
COMPLETE SPECIFICATION.
Improvements in Making an Extract of Tea and a Confection of the
same, and in Preserving Liquid Tea Extracts.
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 present invention consists of certain improvements upon the processes and

page_text: apparatus for the preparation of an extract of tea, described in the Specification to
No. 20,182, 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.
The tea is placed in a closed digester A with perforated false bottom A¹. 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 condese chiefly upon the tea, and the liquor so formed
may be again sucked back as before, and so on as often as necessary.
water reservoir, or supplementary boiler D, is connected by a cock D' and tube D'
to the upper part of the digester A, so that hot or boiling water may be run in
whenever needed. An upright cohobating tube E is secured in the cover A² of the
digester A, and is connected to a series of vessels F F F for condensing aroma-
water and aroma. These arrangements, and the manner of working them are shown
and described in the before-cited Specification.
A hot-
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 it may enter
the digester A by a special inlet. When the digester A is charged with tea, and
water is being heated in the boiler C ready for working, a current of 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 E³ 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 FFF 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.
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 as
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 F¹ or vessels of any other con-
venient shape such as F, for collection of the aroma evolved during the digestion
of the tea. 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 tea infusion in the evaporator G

page_text: 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 tea 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.
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 con-
nected a vessel containing butter, when a solid or pasty extract is to be made ;
otherwise, this is dispensed with. Then come asbestos-charged vessels F1 F2 and
more if desired. All the vessels F F F² 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 tea infusion,
by a tube H 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 C are 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 C³ 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
tea 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 require-
ments. 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 A2, 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 A³, 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 tea 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 tube D2 may be fitted with a joint D₁ which admits of its being turned so that
the branches D³ will for the time-being be vertical. The 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.

page_text: One great advantage of the form of digester now recommended, is that there is no
great thickness of tea, 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 tea. 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 of the digester from near the bottom, and
gange-tube D, and opening in the cover closed by a preferably weighted cover De
for introducing water,
very suitable.
When the digester A. is charged with tea, 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 con-
nection being made to the aroma-condensing vessels F FF, 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 tea. The
proportion thus run in may conveniently be from three to five times the weight of
tea 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 FFF, 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 (supple-
mentary 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 tea. 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 tea, 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
tea 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 of the latter, 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 tea 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 tea may be greatly varied; but usually,
six to ten parts water (apart from the final washings) used in all with one part of
tea, 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

page_text: externally with some suitable bad conductor of heat, to lessen loss of heat by
radiation.
Hops may, if desired, be added in small proportion to the tea infused in the
digester A. But if this is done, it is better, in the subsequent process of
concentration of the infusion in the evaporator G, to bring the liquor to a pasty
consistence, and then to dissolve in hot water, and filter while hot. The filtrate
may then be concentrated, and treated in any of the ways hereinafter indicated, to
obtain a liquid, pasty, or solid extract.
It has been stated that the tea 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 Specification.
As shown in Fig. 3 it is of hemispherical form, with a flange G2 around the edge,
depressed outwards, and provided with a rim G³, and outlet tube G. A conical
hood or cover G³, provided with a cooling water-jacket Go, rests upon the flange G²
close to the rim G³ so that the flange forms a trough or channel G7 into which the
water condensed from the steam produced during evaporation, collects, and flows
through the outlet tube G into 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 tea. 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 G³ to take off uncondensed steam; but with proper cooling
of the hood G by the water-jacket Go, it is unnecessary. The hood G³ should be
provided with an inlet tube Gs for carbon dioxide gas, a current of which is kept
Howing 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 aslíestos, in the manner already described. The aroma water collected
in the small condenser connected to the digester A. in the process of obtaining
the tea infusion, is then added, and the liquid extract, after some agitation, is put
into bottles, which are firmly corked. A portion of the unaromatised 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 tea 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.
A liquid tea extract gives a deposit on standing, which in time becomes con-
solidated, and cannot readily be shaken up. I find that an addition of sugar to
the extract tends to lessen this deposit. Refined cane sugar is preferable. This
I prefer to add, to the liquid, especially if it is intended for long keeping, before

page_text: bottling. A convenient proportion to use is about half as much sugar as there was
of tea used in making the extract. But the sugar is best omitted, or taken in
smaller proportion, or replaced by milk sugar, in making an extract to suit the taste
of those not taking sugar with their tea.
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 concentrated
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, in
the process of obtaining the tea 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.
It will be obvious that a series of digesters A may be worked side by side, in
connection with one or more 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 tea, and for the concentration of the tea infusion, substantially in the
manner described.
(2). The use of butter or its equivalent during the process of digestion of the
tea, as an aroma-absorbing body, and its application in the preparation of a solid or
pasty tea extract or confection, substantially in the manner described.
(3). The use of asbestos or its equivalent during the process of digestion of the
tea, as an aroma-absorbing body; and the recovery of the aroma from the same,
for application in making a liquid or solid extract, 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 tea, in conjunction with a boiler such
as Cof 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 F² substantially as shown in the accom-.
panying drawings.
(5). The aromatisation of tea extracts, whether intended for making liquid,

page_text: pasty, or solid tea 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.