with 400 atmospheres. The construction of the machine is similar to
that of the well-known types of presses used by oil manufacturers for
the preparation of vegetable oils. When pressing, however, the pots
containing the cacao must be rendered water-tight both at the top and
bottom, to prevent the liquid cacao from escaping, while such provision
is not necessary in the case of the oil presses. The stopping up of the
press-pots is effected by means of a side-handle, and arrangements are
provided for heating the pots both from above and below. The machine
illustrated has 4 pots, arranged one above the other, which can be
drawn out on guide-rails towards the front of the machine. During
pressing, they close telescopically with the piston arranged underneath
each pot. The pump which supplies the water for the hydraulic pressure,
works perfectly automatically, increases the pressure according to
the quantity of fat which has run off and keeps the pressure at its
maximum or at any degree required. With these presses it is possible
to extract, without difficulty, 85 % and even more of the total fat of
the cacao bean. If pressing is carried on at too high a temperature,
a pale, whitish grey butter is the result. If, however, a little
attention is paid by the operator at the press, the butter obtained is
usually perfectly clear, as it is first conducted through a horse-hair
pad covered with linen, or a camel-hair cushion 15 millimetres in
thickness. Sufficient attention is not always paid to the operation
of pressing, so that it often happens that some of the cacao escapes
with the butter, which is especially the case if the pressure has been
increased too rapidly at the beginning. If the butter is extracted
for use in the factory itself, the escape of the cacao with it is of
no serious consequence; if, however, the butter is intended for sale
for commercial purposes, its appearance is a most important factor,
wherefore it is advisable to filter the impure fat immediately after
pressing. It is true that, in most factories, the butter is in such
cases merely remelted to allow the impurities to settle to the bottom,
this part being then submitted again to the same treatment, while
the rest of the butter is disposed of on the market. If filtering is
necessary, the butter filter should be used, which, first constructed
in Holland, has been in use for a long time there. The principle of
these filters is to pass the butter through hanging tubes made of a
filtering material similar to flannel.
[Illustration: Fig. 82.]
The firm of Volkmar Hänig & Co. constructs special cocoa butter filters
which can be obtained through the firm of J. M. Lehmann. Figs. 83 and
83a show this type of filter (cross and vertical section), the manner
of working with it being the following:
As soon as the butter has passed through the hair sieve in the upper
part of the apparatus, which removes larger objects such as pieces of
wood etc., it enters the hanging filter tubes, which, to facilitate
cleaning, are interchangeable. The filter butter accumulates in
the large space provided for the purpose and is withdrawn through
a tap. An observing glass is attached to the apparatus for the
purpose of watching the height of the butter, and the whole filter is
water-jacketed, the water being heated by a steam coil fixed in the
bottom of the apparatus. A thermometer is fixed to the side of the
filter, for regulating the temperature.
[Illustration: Figs. 83 and 83 a.]
The degree to which cocoa powders should be defatted is an important
question which, some years ago, formed the subject of much
controversy. The relation between the percentage of fat contained in
the original cacao kernel, the expressed butter and the defatted cacao
mass is shown in tables 19 and 20.
The taste of defatted cacao is, as is well known, all the better for
being defatted to a low degree, and it is this which constitutes the
great advantage of cocoa prepared according to the Dutch method, the
remaining cacao content of which is some 24-33 percent, so that,
taking 50 percent as the average quantity of fat contained in the
cacao, only about 34-52 percent of the whole is removed from the mass.
If the expression of the butter is carried to a further degree, the
cacao will certainly become more easily capable of suspension in
liquids[125], but such treatment is detrimental to its flavour[126],
which is apt to become woody or bitter. The
~Table 19.~
Percentage of butter to be extracted.
========================================================================
Percentage of fat |
to remain in the | Fat content of kernel
finished cocoa |
powder | 50% | 51% | 52% | 53% | 54% | 55% | 56%
=======================+======+======+======+======+======+======+====
| Weight of butter to be expressed
| (in proportion to the whole mass)
{33% |25·4 |26·9 |28·4 |29·8 |31·3 |32·8 |34·4
| | | | | | |
{32% |26·5 |27·8 |29 |30·9 |32·4 |33·3 |35·3
{ | | | | | | |
{31% |27·5 |29 |30·4 |31·9 |33·3 |34·8 |36·2
{ | | | | | | |
{30% |28·6 |30 |31·4 |32·9 |34·3 |35·7 |37·1
{ | | | | | | |
Fatty Cacao {29% |29·6 |31 |32·4 |33·8 |35·2 |36·6 |38
{ | | | | | | |
{28% |30·6 |31·9 |33·3 |34·7 |36·2 |37·5 |38·9
{ | | | | | | |
{27% |31·5 |32·9 |34·2 |35·6 |37 |38·4 |39·7
{ | | | | | | |
{26% |32·4 |33·8 |35·1 |36·5 |37·8 |39·2 |40·5
{ | | | | | | |
{25% |33·3 |34·7 |36 |37·3 |38·7 |40 |41·3
——————————————————————-+——————+——————+——————+——————+——————+——————+————
{24% |34·2 |35·5 |36·9 |38·2 |39·5 |40·8 |42·1
{ | | | | | | |
{23% |35·1 |36·4 |37·7 |39 |40·3 |41·6 |42·9
{ | | | | | | |
{22% |35·9 |37·2 |38·5 |39·8 |41 |42·3 |43·6
{ | | | | | | |
{21% |36·7 |38 |39·2 |40·5 |41·8 |43 |44·3
Non-fatty Cacao { | | | | | | |
{20% |37·5 |38·8 |40 |41·3 |42·5 |43·8 |45
{ | | | | | | |
{19% |38·3 |39 |40·7 |42 |43·2 |44·5 |45·7
{ | | | | | | |
{18% |39 |40·2 |41·5 |42·7 |43·9 |45·1 |46·3
{ | | | | | | |
{17% |39·7 |41 |42·2 |43·4 |44·6 |45·8 |47
——————————————————————-+——————+——————+——————+——————+——————+——————+————
Diminution {(16%)|(40·4)|(41·7)|(42·9)|(44) |(45·2)|(46·4)|(47·6)
in { | | | | | | |
value K. {(15%)|(41·1)|(42·4)|(43·5)|(44·7)|(45·9)|(47·1)|(48·2)
——————————————————
~Table 20.~
=Percentage of butter remaining in the finished cocoa powder.=
=================++================================================
Weight of butter ||
to be expressed, || Fat content of kernel
in proportion to || | | | | | |
the whole mass || 50% | 51% | 52% | 53% | 54% | 55% | 56%
=================++======+======+======+======+======+======+======
||
{ 30% || 28·6 | 30 | 31·4 | 32·9 | 34·3 | 35·7 | 37·1
Fatty { 31% || 27·5 | 29 | 30·4 | 31·9 | 33·3 | 34·8 | 36·2
Cacao { 32% || 26·5 | 27·9 | 29·4 | 30·9 | 32·3 | 33·8 | 35·3
{ 33% || 25·4 | 26·9 | 28·4 | 29·9 | 31·3 | 32·8 | 34·3
{ 34% || 24·2 | 25·8 | 27·3 | 28·8 | 30·3 | 31·8 | 33·3
====++======+ | | | | |
{ 35% || 23·1 | 24·6 | 26·2 | 27·7 | 29·2 | 30·8 | 32·3
{ || +======+ | | | |
{ 36% || 21·9 | 23·4 | 25 | 26·6 | 28·1 | 29·7 | 31·3
Non- { || | +======+ | | |
fatty { 37% || 20·6 | 22·2 | 23·8 | 25·4 | 27 | 28·6 | 30·2
Cacao { 38% || 19·4 | 21 | 22·6 | 24·2 | 25·8 | 27·4 | 29
{ || | | +======+ | |
{ 39% || 18 | 19·7 | 21·3 | 23 | 24·6 | 26·2 | 27·9
{ || | | | +======+ |
{ 40% || 16·7 | 18·3 | 20 | 21·7 | 23·3 | 25 | 26·7
====++======+ | | | +======+
{ 41% ||(15·3)| 16·9 | 18·6 | 20·3 | 22 | 23·7 | 25·4
{ || +======+ | | | +======
{ 42% ||(13·8)|(15·5)| 17·2 | 19 | 20·7 | 22·4 | 24·1
{ || | +======+ | | |
{ 43% ||(12·3)|(14) |(15·8)| 17·5 | 19·3 | 21·1 | 22·8
Diminu- { || | | +======+ | |
tion in { 44% ||(10·7)|(12·5)|(14·3)|(16) | 17·9 | 19·6 | 21·4
value K. { 45% || — |(10·9)|(12·7)|(14·5)| 16·4 | 18·2 | 20
{ || | | | +======+ |
{ 46% || — | — |(11·1)|(13) |(14·8)| 16·7 | 18·5
{ || | | | | +======+
{ 47% || — | — | — |(11·3)|(13·2)|(15·1)| 17
{ || | | | | | +======
{ 48% || — | — | — | — |(11·5)|(13·5)|(15·4)
[Illustration: Fig. 84.]
[Illustration: Fig. 84a.]
statement, made by certain manufacturers and would-be connoisseurs,
that the bitter taste peculiar to the acid produced in cacao during
fermentation is the real aroma of the cacao, is undoubtedly erroneous.
It could, in the same way, be said of tea and its acids, the bitterer,
the better; which would of course end in the destruction of the true
flavour. Equally erroneous is the theory that bitter cacao is more
consistent. Such cacao must, previous to consumption, either be more
sweetened than usual or, if the same quantity of sugar is put in, less
of the beverage can be taken. When, for instance, very thin coffee
is made, the beans, on colouring an abnormally large quantity of
water, are said to be stronger, i. e. to yield more. The consistency
of all such beverages is, however, only a matter of taste, and it
would therefore be useless to discuss the subject in detail; some
persons prefer strong tea, which has been brewed a quarter of an hour,
others simply pour boiling water over the tea leaves and then drink
the beverage immediately. It may, however, safely be taken that the
highest amount of butter which can be expressed from cacao without
prejudicing the flavour of the finished powder is 66 percent of the
total fat content. Manufacturers nowadays try as a rule to express as
much butter as possible, as the butter has a high price on the market,
and this tendency naturally has the effect of lowering the quality of
the cocoa. We thus come across cocoa powders containing only 20, 17, 15
percent of fat and even less. Of course nothing can be said against
the production of such cocoas, provided they are sold at a lower price
than cocoas more rich in fat and the public are aware that they are
purchasing a non-fatty preparation, besides which the expression of
so high a percentage of the fat alone rendered cocoa a fit regular
beverage for certain classes of invalids and persons suffering from
disorders of the stomach. The only serious drawback in this case is
the great variability of the fat content, which fluctuates between
13 and 35 percent. Such fluctuations are absolutely impossible in
the case of any other article of food which is manufactured and sold
wholesale, or, at any rate, buyers know in all such cases exactly what
they are purchasing; this is a point to which serious attention must be
called. It is very much to be regretted that the Association of German
Chocolate Makers[127] has declined to follow up this matter, while
the Union of German Food Chemists, after considerable controversy,
advocated a distinct legal classification of non-fatty cocoa powders
containing up to 20 percent of fat.[128] We would prefer the Dutch
preparations, which have remained the same up to the present day,
so-called fatty cocoas containing more than 25 percent of fat, to be
classified specially and those preparations which contain less than
this percentage of fat to be termed “highly defatted” or “dry” cocoas,
the names applied to both kinds being of little importance as long as
the public has the means of clearly recognising the distinction (see
tables 19 and 20). Some 17 percent must be taken as the minimum
permissible butter value, which would mean the expression of about 80
percent of the total fat content, or two-thirds of the cacao mass
itself; cocoa powders with only 15 percent or less of butter are
to be regarded as inferior in quality and should not be produced.
Unfortunately, however, these suggested limits are, at any rate for the
present, not likely to be realised.
[Illustration: Fig. 84b.]
[Illustration: Fig. 85a.]
The pressure obtained by means of the pressing devices above described
is naturally not sufficient for the production of such highly defatted
cocoas. Stronger presses are therefore necessary, one of which, a very
powerful apparatus, is shown in Fig. 84.
This machine, at the present time the most powerful cocoa butter press
in the world, brings a pressure of over one million kilos to bear on
the cacao mass, working with 400 atmospheres, and thus renders it
possible to express as much as 90 percent of the total fat content
of the bean. The construction of this press is exactly the same as
that shown in Fig. 82, the pump Fig. 84a having, however, three
pistons or plungers instead of one; it works, like the other machine,
automatically, i. e., after the large quantity of water required at
the commencement has been fed into the press, the large plunger is put
out of gear at a pressure of 5 atmospheres; the two smaller pistons
are then put into action together, and produce the enormous pressure
of 400 atmospheres.
[Illustration: Fig. 85b.]
After defatting, the expressed cacao cakes are allowed to cool down,
for which purpose they are transferred to flat trays or other suitable
receptacles, and pulverising and sifting the powder thus obtained
commenced.
3. ~Pulverising and Sifting the Defatted Cacao.~
There are several methods of proceeding with these operations, such
as treating the expressed cacao in the melangeur already described
in an earlier part of this book (cf. 30-32 figs.) or passing it
through the centrifugal sifting machine (cf. 84b and 88 figs.) with
which we are now acquainted. At a time when the melangeur was to a
certain extent the universal machine of the manufacturer, it was almost
exclusively utilised for pulverisation, that up-to-date division of
labour whereby this machine is limited to mixing (and very properly so
limited, as its name implies) and the preparation of cacao powders on
the contrary assigned to more efficient constructions having then not
as yet been adopted. We annex a description of one or two specially
constructed arrangements for the pulverisation and sifting of cacao, as
manufactured by J. M. Lehmann and already repeatedly tested.
[Illustration: Fig. 86.]
First there is the cacao cake crusher (figs. 85a and 85b), which
reduces the pressed cake into rather large pieces about the size of
a walnut, previous to its being pulverised either in the melangeur,
centrifugal sifting machine or some similar apparatus. It has been
furnished with one (fig. 85a) and in some cases even with two (fig.
85b) pair of toothed or cogged rollers, and the cacao in this latter
type of construction is crushed as small as a pea, which reduction,
although it is by no means essential, considerably relieves the strain
on the pulverising machine and is also in some sort a protection
against unnecessary waste of material.
[Illustration: Fig. 87.]
Then again, there is the so-called pulveriser shown in fig. 86. This is
in principle an edge-mill with revolving bed-stone and runners, both
made of granite. The coarsely broken press cakes are fed into the mill
through a hopper provided with a slide, and are reduced to a loose
powder of firmly fixed colour, escape of dust being prevented by the
hood fitted to the mill. By turning a crank, a lateral sliding door is
opened, and an arrangement inside is set in motion, by which the ground
cacao is turned out of the mill. The pressure of the runners can be
diminished and even completely nullified.
For cacao that has been thoroughly defatted (“dry” cocoa), the hardness
of which demands a more efficient treatment than is possible in these
machines, they being only calculated to press or at the most exert a
rubbing effect, there are the crushers proper, called mills built in
pulverising plants for dry cocoas as illustrated on fig. 87.
The pressed cacao, already broken up to some extent in a preliminary
crusher (cf. figs. 85a and b), is systematically conducted through the
mill by an elevator provided with hopper and feeding apparatus. On the
interior of the machine, which is completely plated with steel-plates,
there is a cross-arm as on a windmill, which passes through a large
number of revolutions per minute. Chiefly owing to its thrashing
effect, the cacao in the mill is fine ground, without any rubbing
or exertion of pressure as in the melangeur and other machines. The
outer part of the frame consists of a grating with various widths of
hole, which can be readily changed. The whole of the powder which has
attained a certain degree of fineness falls through these meshes and is
so despatched from the machine at once, an additional advantage when
comparing this mill with the melangeur, in which all the powder, even
that sufficiently ground, must remain till the final discharging, much
to the detriment of its flavour and aroma.
[Illustration: Fig. 88.]
The powdered cacao next succeeds to the sifting operations, after it
has first cooled a little, and for these the centrifugal sifting
machines are used in the main. Special care must be taken that such
apparatus as is used is not too diminutive to deal with the quantities
of cacao introduced, as this is extremely injurious to the machine. It
is further to be noted that no type of sifter whatever can yield good
results if it has not been especially constructed for dry cacaos.
We have before us in fig. 88 centrifugal sifting machine constructed
on one of the largest scales. In this cacao is introduced in the
floor of the sieve through a feeder, and by means of an elevator. The
sifting cylinder is spanned with silk or bronze gauze, and conceals in
its interior a rough sort of preliminary sieve, the purpose of which
is to prevent the larger unpowdered pieces penetrating to the silk
gauze. There is a ventilator inside this rough sieve, which produces
and transmits an air current, so that the meshes are kept open. Under
proper guidance it is practically impossible for the machine to break
down, although the sieve must be cleansed twice daily, an operation
scarcely requiring more than two or three minutes, as it is not
necessary first to remove the part under consideration. Because of this
easy manner of cleaning, the centrifugal sifter far excels all others,
as the plan sifter, the latter generally having to be dismounted before
this operation can be proceeded with.
The powder issues from the first outlet of the sieve. There is a
second, where both preliminary and cylinder sieve transmit their
overflow, and this is then again conducted to the pulveriser in order
to be worked up once more. Pulverisers and sifting apparatus can
be so combined by means of conveyors and elevators that they work
automatically, which is always of immense advantage where a large daily
output is in question. But pressed cakes which are to be conducted
through the machine in broken pieces must first be treated in a
preliminary crusher (cf. figs. 85a and b).
Fig. 88a shows one of the plansieves of the firm Baumeister, and
protected by patent, which also finds employment for the sieving of
cacao powder.
This machine possesses four round sieves lying one upon another, on
which the material to be sieved is moved by a crank driving power
just as on a hand sieve, so that the surface of the sieve is fully
employed. The sieves possess neither projection nor hauling gear, the
sieving is effected without pressure or friction, and the powder is
therefore loose and woolly. A brushing arrangement revolves without any
mechanism, driven solely by the peculiar movement of the plansieve,
under the wholly flat sieves, and this brushing arrangement any cacao
powder which may adhere to the sieve and so prevents a displacement of
the tension, as far as possible.
[Illustration: Fig. 89.]
In the following illustration we give as an example the arrangement of
a pulverising plant with pulverisers (cf. fig. 86) for a second time.
The preliminary crusher receives the cakes, and then a conveyor brings
the broken pieces along to the elevator, which in its turn feeds the
filling box of the pulveriser, the connection between the two being
established by a sliding platform. The discharged material succeeds on
a landing where it is cooled down a little. A second conveyor brings
it to the elevator of the sifting machine. Whilst the fine powder is
taken up in barrels collectively introduced under the apparatus, the
remainder of the cacao passes along to the conveyor first mentioned,
is mixed with other broken pieces of cacao cake, and so returns to the
pulveriser.
In reference to the Dutch method of disintegration, mention must be
made of the process adopted by Moser & Co. in Stuttgart[129], where the
cleansed, shelled and moistened beans are enclosed in a rotating drum,
so that they can be subjected to the influence of ammonia and water
vapour, produced from a solution of ammonium carbonate, which is passed
through the hollow interior of the drum. The beans are then roasted and
so freed of superfluous ammonia, after which follow in regular order
the processes of grinding, defatting and pulverising.
After this description of the Dutch and other well-known methods of
disintegration obtaining in the manufacture of cocoa powder, we shall
now proceed to describe such of the remaining processes as seem to
deserve mention.
c. Disintegration after Roasting.
The chief difference between the following methods of procedure and
the Dutch and other processes previously referred to is that in the
former the beans are neither impregnated with alkalis before nor during
the roasting, but after it has been carried out, and the impregnation
occurs sometimes prior, and at other times subsequent, to the
expression of the fat. The several stages of treatment which proceed
this process succeed each other in the same order as in the preparation
of chocolate, cleansing, sorting, roasting, crushing, shelling and
trituration following one after the other. But if the treatment with
alkali is to take place before the fat is expressed, the cacao passes
from the grinding mill direct to the apparatus in which it is subjected
to the action of a solution of potash or some other alkali.
1. ~Disintegration prior to Pressing.~
The system of impregnating the ground but as yet undefatted beans with
alkali was first introduced into Germany by Otto Rüger, Lockwitzgrund.
The principle features of the Rüger process are similar to those of
other methods at present frequently met with, so that a detailed
description would seem to be rather superfluous. Melangeurs may be
conveniently employed in the treatment of cacao mass in a liquid state
with alkalis, such as we have previously described, and illustrated in
fig. 86 on page 210.
[Illustration: Fig. 90 a.]
As preparing machines for disintegration, the kneading and mixing
apparatus shown in working position in fig. 28, page 118, and in fig.
90 a with tilted trough for emptying are specially constructed and
patented and quite deserve the popularity they have acquired.
[Illustration: Fig. 90 b.]
[Illustration: Fig. 90 c.]
[Illustration: Fig. 91 a.]
Their construction and method of working are described on page 118.
Other well-known machines for the purpose are the “Universal” mixing
and kneading machines patented by Werner & Pfleiderer, which are shown
in figs. 90 b and 90 c. As regards the general outlines of their
construction, it will suffice to refer to the excellent descriptions
of the machines which occur in the catalogues issued by this firm.
Mention cannot fail to be made, however, of the circumstance that
in these machines the evaporation of the alkaline solvent is also
effected. The working of the kneading arms facilitates the escape of
vapour from the mass and prevents overheating from contact with the
walls of the apparatus. Underneath, the trough is provided with a
double jacket, that is heated by steam.
To maintain connection of the steam and water pipes whilst the trough
is reversed there are two flexible metal tubes. Both are screwed to
the fixed pipes. For carrying away the vapour given off there is a
tin plate cover to the trough, provided with a charging aperture and
a channel inside to catch the moisture collecting on the cover and
discharge it. When the machine is to be emptied, the cover is raised
and a receiver adapted to the size and form of the machine is so placed
that the charge can be diverted into it. The tilting of the machine is
effected mechanically, and depends on the working of a lever. So as to
prevent spurting of the liquid material when discharging, the stirring
arms can be stopped for a time.