ever increasing popularity, partly because they are heated indirectly,
and again because they appreciably diminish the time taken up in the
actual process, which in other cases approaches to as much as thirty or
forty minutes, without exposing the beans to the danger of burning or
getting charred.
As just stated, the beans should be passed on to the next process as
speedily as possible, yet on the other hand be completely cooled
off, so as to loosen their shells before they arrive in the breaking
machine. There are also special constructions for this cooling. If the
roasting drums are fitted up directly on the ground, it is effected
by disposing the beans issuing from these machines in wide baskets or
sieves, and letting them cool there before bringing them to the next
process. Should they be situated at a sufficient height, the beans can
be slowly transferred down a shoot connected with the rooms below,
where crushing mills await them, and cooled on the journey by a play of
fresh air currents.
Very much to the purpose and well adapted as regards most of the
requisite conditions, are the cooling trucks with exhaust apparatus
shown in fig. 17.
These trucks are fitted with perforated false bottoms and with sliding
shutters at the side. After the contents of the roasting machine have
been discharged into the trucks, these are wheeled over to the exhaust
apparatus easily recognisable in the diagram, where the cacao is so far
cooled that subsequent “after-roasting” is impossible, whilst the gases
given off are conducted by the ventilator. This exhaust chamber can be
made to work from both sides.
3. ~Crushing, hulling and cleansing.~
Up to ten years ago, the crushing and shelling of cacao beans had not
been so far perfected as to effect the complete separation of husk and
radicle from all particles of kernel, or to prevent loss by isolating
and collecting the minute particles of kernel, which are drawn up
through the exhaust apparatus in conjunction with the lightest of the
cacao shells. Yet the requirements demanded of a satisfactory machine
advanced to such an extent that not only cacao nibs free from shell
were postulated—an end scarcely hard to attain—but shells free from
cacao nibs were made a further essential. A machine which performs
both these objects not only works excellently, but is also economical.
For a solution of this problem the Association of German Chocolate
Manufacturers, which is specially interested in all that concerns
the chocolate industry, offered a prize years ago; the firm of J. M.
Lehmann were the first to construct a machine answering every call made
on it to perfection.
Fig. 18 illustrates a crushing and cleansing machine averaging an
output of 2500-3000 kilos, of the latest and most modern type.
[Illustration: Fig. 18.]
The beans are first broken into smaller pieces in all machines now
employed as crushing, shelling or cleansing apparatus, and the one at
present under consideration provides no exception. An air-current is
made to play on these fragments, which finally isolates and transfers
the loosened shells to another part of the apparatus. The cacao next
succeeds to a crusher of regular capacity lodged in the upper part of
the machine, being despatched on an elevator. The fragments fall into
a cylindrical sieve, dust being detached in the first compartment,
whilst the meshes of subsequent compartments gradually increase in
size and sort the products therein transmitted in corresponding
sizes. There is a groove traversed by air-currents—proceeding from a
ventilator—immediately under each compartment. This current of air can
be regulated, i. e. made weaker for lighter and stronger for heavier
fragments, and there is a ventilator for every compartment to make this
regulation of the easiest, and in this way shells of equal size but
specifically lighter than, the cacao fragments are most efficaciously
separated. Contrasting with the older type of machine, it works almost
noiselessly, all shakings of grooves and sieves being entirely avoided;
in addition to which there is a perfect exclusion of dust, when the
shells are transferred into the dust-removing chamber. A further
advantage is that there is no wearing out of the machine, except as
regards the direct crushing apparatus, which occasionally need renewing.
The dust particles before mentioned, which possibly comprise as much
as one half of the cacao fragments, require a special kind of working
up, on ~different machines~, before the cacao still contained
therein can be obtained. It is a fact obvious and apparent, that the
smaller the fragments of shell mixed with this crushed cacao, the
more difficult will be their separation, a fact of equal importance
to technical and analytical science, and the more scrupulously this
process is to be carried out, the greater the lavishment on sieves and
ventilating compartments entailed.
To effect this operation on the breaking machine is seriously to
overtask the latter, and defeats its own end, as experiments carried
out in the Chocolate factory of Schütte-Felsche have proved, inasmuch
as it leads very easily to mixing of the products which are to be kept
separate.
Fig. 19 shows such a machine for the cleansing of this so-called cacao
“dust
The particles are raised to a large flat sieve by means of an elevator,
again sorted in different sizes, and submitted to air currents of
corresponding strength. The quantity obtained varies according to
the variety of cacao, though in some cases it may amount to 50 or 54
percent. What remains after this process is absolutely worthless and
can only be considered as refuse, at least as far as the chocolate
manufacturer is concerned.
[Illustration: Fig. 19.]
It has become necessary in modern manufacture that iron fragments
occurring in the machine not only be separated by distinct magnetic
fields in the respective machines, but that this also be effected in a
machine specially constructed for the purpose. Fig. 20 illustrates such
an electromagnetic apparatus. The advantages of this system are that it
avoids magnets limited in strength, and by the functioning of strong
electro-magnets perfect cleansing even in the case of the largest
output, as well as machines of the most simple construction, can be
guaranteed.
We submit the following description of the machine and its method of
working.
[Illustration: Fig. 20.]
The machine contains a hopper with sloping groove to obtain an even
introduction of the beans to be cleansed. At the end of this there is
an electro-magnet roller, consisting of a non-magnetised mantle and a
magnetic compartment round which it turns.
After traversing the sloping groove, the beans succeed to the roller,
meeting it at a tangent. As soon as they reach the field of magnetism,
all iron fragments are appropriated by the revolving mantle, whilst the
beans themselves do not come into contact with this, but pass directly
underneath. The iron fragments are disposed of separately, and outside
the magnetising area.
It is of prime importance in the preparation of chocolate and more
particularly of cocoa powder (easily soluble cacao), that the crushed
material proceeding from the crushing machine should undergo a
further purification, with a view to separating, and removing the
hard radicles. These constitute the gritty sediment of insufficiently
prepared cacao powder, when dissolved. J. M. Lehmann effects the
complete removal of the radicle by means of his machine D. R. G. M. No.
24,989 (Fig. 21).
[Illustration: Fig. 21.]
Here the finer siftings from the crusher are transferred to the
controlling feeder, under which a small ventilator occurs, which
provides for the removal of any still remaining portions of husk.
Cacao and radicle descend to a shaking sieve, the finer particles
passing through its meshes, whilst the larger grains fall into a
pocket attached to the end, as cleansed product. The former fragments
now succeed to a cylinder, having its inner surface punched with
small cavities (fig. 22) and while the cacao particles remain in
those cavities during the rotation of the cylinder, the radicles of
more elongated form are caught up by a special separator (1) and so
prevented from being carried round with the rest. The cacao particles
are then made to fall into a trough (3) by a brush (2) working against
the cylinder, and subsequently urged forward by a conveyor (4). That
process is enacted all along the cylinder, so that finally cacao and
radicle issue from the machine completely separated.
[Illustration: Fig. 22.]
The advantages, economical and otherwise, attending the use of the
above breaking and cleansing machines become apparent when the
following figures, registering results obtained in several experiments,
are considered. Formerly the loss experienced in sorting, roasting,
crushing and hulling averaged about 30 % of the total beans, but now
the employment of the above machines shows the following satisfactory
improvements.
The loss of 823 kg Machala beans, unroasted, amounted to a total:
a) in picking 3·6 kg
b) " roasting 63·5 "
c) " shelling 61 "
d) " dust 34 "
—————————
162·1 kg or 20%,
without taking into account the application of the waste; 2267 kg of
St. Thomé raw cacao lost:
a) in picking 5 kg
b) " roasting 170 "
c) " shelling 152 "
d) " dust 79 "
—————————
406 kg or 20%.
According to these data the use of these machines admits of a saving of
about 10 percent more material than in former work.
In connection with these particulars it is also of interest to consider
the qualitative and quantitative composition of the various waste
products of the manufacture. Filsinger[112] has at the instance of
the Association of German Chocolate manufacturers, examined a mixture
of 50 pounds of large Machala beans with an equal quantity of small
beans, after passing it through a shelling machine of the most modern
construction, and he thus obtained:
70 pounds of large kernels,
9·2 “ " medium kernels,
0·8 " " radicles,
10 " " husk (outer woody shell),
4 " " cacao waste,
6 " " other loss,
The 4 pounds of cacao waste yielded by further sifting:
a) kernel I. sort 250 grammes,
II. " 50 "
III. " 220 "
IV. " 25 "
b) husk I. " 185 "
II. " 55 "
III. " 370 "
IV. " 80 "
c) cacao dust 725 "
d) waste 30 "
e) loss 10 "
————————
2000 grammes.
Chemical analysis of these portions gave the following results:
======================================+================================
| Percentages
+———-—-—+—-—-——+————--—+——-—-——-
| Ash | Sand | Fat |Fibre[113]
——————————————————————————————————————+—————-—+——————+—————-—+———————-
1. Husk 10% of the raw cacao | 11·15 | 1·90 | 4·50 | 21·36
2. Cacao waste 4% of the raw cacao | 4·80 | 0·35 | 15·40 | 16·31
3. Seed shells I. sort 0·37% of | 6·70 | — | 21·64 | 10·29
the raw cacao
4. " " II. " 0·11% " " | 7·10 | — | 18·39 | 8·75
5. " " III. " 0·74% " " | 7·20 | — | 15·76 | 12·16
6. " " IV. " 0·16% " " | 7·80 | — | 16·40 | 12·74
7. Cacao dust 1·45% of the raw cacao | 11·75 | — | 22·06 | 8·40
8. Waste 0·06% of the raw cacao | 7·05 | — | 20·44 | 9·81
From these data it is evident that there is a great difference between
the chemical composition of the so called cacao waste and that of the
exterior ligneous shells. From the large amount of fat present in the
former material it might be regarded, in the full sense of the term,
as a cacao constituent and, for that reason, its presence in cacao
preparations should not be objected to, while the husk containing
as much as 20 percent of woody fibre cannot be considered a cacao
constituent in the same sense.
4. ~Mixing different kinds.~
Stress has already been laid on the variations in taste incidental to
different species of bean. It has further to be noted that they develop
a milder and more aromatic flavour according as they have been more
properly fermented, and in contrary instances possess an astringent and
even acid taste. It therefore becomes an aim of the manufacturer so
to improve the flavour of inferior varieties by mixing with the finer
as to produce a resultant cacao giving perfect satisfaction to every
taste. Nevertheless the general rule still holds good that for the
preparation of the finest qualities of chocolate only the better sorts
of bean (as Caracas, Ariba, Puerto Cabello etc.) should be employed.
For inferior and less expensive ware other varieties of bean suffice,
the mixture being obviously regulated by the prevailing market prices.
In many instances the proportions of such mixtures are kept secret
by the manufacturer as matters of importance, and every individual
manufacturer has his own method and specialities as regards such
blends.
We compare here a few verified blends:
1.
Caracas }
Guayaquil} of each 1 part
2.
Caracas = 1 part
Bahia = 5 parts
3.
Maracaibo}
Maragnon } each 1 part
4.
Trinidad}
Maragnon} equal parts
5.
Caracas = 1 part
Maragnon = 2 parts
6.
1 part Ariba
1 part Surinam
1 part Trinidad
7.
1 part Ariba
1 part Trinidad
1 part Surinam
1 part Caracas
8.
3 parts Ariba
1 part Trinidad
1 part Surinam
1 part Caracas
9.
1 part Machala
1 part St. Thomas
Ceylon cacaos are not used so much as mixing varieties, but almost
exclusively as covering agents, to make other cacaos lighter coloured
(sometimes almost approaching yellow).
The beans are weighed off in these proportions on a sensitive scale,
and then passed on to be ground and triturated into cacao paste.
II. Production of the Cacao Mass.
5. ~Fine grinding and trituration.~
Formerly the roasted, crushed, and decorticated beans were frequently
ground before being transferred to the “Melangeur”,—a machine that will
be described later—, in which they were then reduced to a finer state
of sub-division and lastly mixed with sugar. For this grinding, mills
of various construction were employed (as Weldon, Pintus etc.). But
as time rolled on the Melangeur took the place of these preliminary
grinding mills, and in this it was endeavoured to effect that fine
division of the cacao mass which is essential to the production of a
homogeneous cacao and sugar intermixture, but without complete success.
Cylinder rolling machines (French method) were the first to attain this
result.
At the present time, the roasted and cleansed kernels are ground so
fine as to become a semi-liquid when subjected to heat, and that
is done whatever the ultimate destiny of the cacao, whether it be
intended for chocolate or cocoa powder. This object is obtained by
means of special mills, constructed with “Over-runners
[Illustration: Fig. 23.]
[Illustration: Fig. 24 a.]
These cacao mills, which were formerly but seldom met with in chocolate
factories, have now become indispensable necessaries, since they have
the advantage:
1. of rendering the cacao mass in this semi-glucose form more easily
miscible with sugar, a factor of the highest importance for the
commoner and cheaper qualities of chocolate;
2. of grinding the cacao as fine as possible in one operation and the
simplest manner.
[Illustration: Fig. 24 b.]
[Illustration: Fig. 24 c.]
But side by side with the appreciation which these mills met with,
there arose a corresponding increase in the demands made on them, such
as the utmost nicety, greatest possible output, and least possible
necessity of after-heating, and these have been successively answered
by twin, triple and at the present time even quadruple mills. fig. 23
shows a simple grinding mill which can only come into consideration
in connection with the smallest of branches, whilst Fig. 24 a and b
illustrates another with three successive stones arranged one above the
other, such as will be found in all the larger factories of to-day.
Also a triple mill but with grindstones of increasing size pictured in
fig. 24 c. A mill possessing four pairs of grinding stones is given in
fig. 25, and is calculated to meet each and every conceivable demand.
Whilst simple, double and triple mills are brought on the market in
different sizes, corresponding to the outputs required, these quadruple
mills are only constructed in the largest sizes. They grind perfectly,
and without detriment to the flavour, deliver quantities of cacao
figuring at from 1000 to 1200 kilos daily. There is naturally a larger
output if the fatty contents of the cacao are considerable, a thorough
roasting being always presupposed.
The axles occurring on these quadruple grinding mills are connected
with one another by means of spur-wheels, and the axles themselves
run in ball-bearings, which not only permits a perfectly noiseless
operation of the machine, but also makes the action very easy, that is
to say, dependent on only very little motor power. The cacao is raised
to the hopper by means of an elevator, where the quantity introduced
into the machine is regulated, and then passes between crushers
occurring in the middle of the first pair of grinding stones, which
it subsequently leaves as a pasty mass. It is then conducted along
a groove into the second mill, and here undergoes further grinding,
and so to the third and fourth, where the process can be described as
trituration, for the cacao leaves the machine in liquid form. Only in
this manner is it possible to obtain the finest ground product, without
any disastrous accompaniment of excessive heating.
Cacao mills with one stone suffice for the production of chocolate mass
on a small scale, but for the manufacture of cocoa powder, twin or
triple grinders must be employed.
All these are of the “Over-runner” type, act by their own weight, and
consequently do not involve the disastrous consequences which were
entailed by the “Under-runners” tried formerly.
About the middle of the nineties of the last century, experiments were
made with a view to superseding these types with mills having stones of
varying sizes, and first larger upper stones of a grinding pair were
tried, then larger under stones, but neither have been able to maintain
themselves in the workshop, and the grinders of equal size still hold
good as the fittest and most popular.
[Illustration: Fig. 25.]
Attempts have recently been made to introduce a machine combining mill
and roller. Its value lies in the fact that with a relative increase
in the grinding rapidity, it does not involve a greater than requisite
heat, and on emerging from the machine the cacao shows no deficiencies
as to flavour, and is withal much finer than that produced in other
processes.
[Illustration: Fig. 26.]
Fig. 26 shows such a machine. The mill on this serves merely to reduce
the hard kernel to a pulp, and this admits of the grinding stones being
placed farther apart, and so occasions no heat. Trituration is then
effected by a roller apparatus, for which operation machines with four
rollers have been proved most satisfactory. As such roller machines are
furnished with water-cooling systems, it is possible for the cacao to
be kept cool even on these.
6. ~Mixture with sugar and spices.~
[Illustration: Fig. 27.]
A thorough mixing with sugar can only be effected when the cacao paste
is heated to a temperature rather above the melting point of cacao
butter, that is to say, as high as from 35° to 40° C., and consequently
the incorporating machine in which that operation is carried on is
provided with a steam jacket. For this process it is advisable to
have the chocolate in a semi-liquid condition, wherefore the ground
cacao issuing from the mills is transferred to steam-heated vessels
(fig. 27) fitted with taps suitable for drawing off the mass as it is
required. Formerly the cacao mass was fed into the melangeur in lumps
and there liquefied. But as this necessitated the application of heat
to the melangeur, attended with the risk of cracking its under-plating,
and also a postponement of the mixing processes, whereby considerable
time was lost, this method no longer obtains to-day. It is at present
usual not only to warm the cacao mass beforehand, but the sugar also,
by storing it in warm chambers, so that the whole paste possesses
a uniform temperature, lowering of temperature in the melangeur is
avoided, and there is consequently no waste of the heating steam.
In some large factories the actual incorporation of cacao and sugar
is preceded by a preliminary mixing of large quantities, which
considerably relieves the strain on the melangeur, whilst it keeps the
machine rooms as far as possible free from superfluous dust.
[Illustration: Fig. 28.]
The mixing machine shown in fig. 28 can here be used with advantage.
As will be seen on comparing the illustration, it is provided with a
shifting trough. Such a machine, when closed down, is capable of mixing
from 100-500 kilos of chocolate. The mixing is effected by means of two
suitably shaped blades, and the heating by a steam jacket. After the
operation is completed, the mixed material is turned out into portable
troughs, and after having been kept in a warm chamber for some length
of time, transferred to the melangeur for further treatment.
It has been found advantageous to keep the chocolate mass so obtained
in suitable receptacles for several days[114], at a temperature of
not less than 20° C. and between that figure and 40° C. So the sugar
is enabled to penetrate the entire mass, which now proceeds to the
rolling processes carried out in the melangeur and rolling machines.
Shortly before its discharge from the latter, it is mixed with spices,
vanillin, eatherial oils and so forth.
[Illustration: Fig. 29.]
7. ~Treatment of the Mixture.~
a) Trituration.
In describing the mixing machines, we do not intend to enter into
details regarding the machines formerly in use, but merely to give a
brief outline of the principles illustrated in their construction.
Trituration was formerly produced;
1. by rollers running backwards and forwards on a grinder;
2. by several cones rotating in a circle on a disc-shaped bed;
3. by means of rotating stones running in a trough;
4. by means of several cylindrical rollers;
5. by means of grooved cone moving in a grooved casing.[115]
At the present time only the type mentioned under 1. and 4. are in
general use. 3. is met with less frequently, and will be described at
greater length in a subsequent paragraph.
The machines 1. and 3. are put into operation prior to the cylinder
rolling mills, which finish off the incorporation of chocolate and
sugar and the levigation process only begun in the first-named.
The machines constructed in the manner described under 3., to which we
now turn, were introduced by G. Hermann of Paris, but are at present
almost obsolete. Since they have some historical interest and are
typical of the development of the melangeur, we annex a rough sketch
showing their general construction in fig. 29.
The ellipsoid runners _a_ made of granite work in the trough _i_ which
is also of granite and is fitted with the casing _h_. The runners
rotate on their axles _b_ so as to move in a circle. The two arms of
the axis _b_ have at the centre an elliptical ring with a quadrangular
opening, into which fits the similar shaped part of the vertical shaft
_c_ fitted with the toothed wheels, _d_ and _d′_, which are set in
motion by power transmitted to the shaft and its connections. The arm
_b_ has some play downwards, so that it can adjust itself vertically
according to the greater or less quantity of material in the mill. The
two steel blades, _e_ and _e′_, are shaped to fit the cavity of the
trough; being connected with the shaft _c_ they revolve with it and
sweep down the cacao mass adhering to the sides of the mill. Between
the foundation _k_ and the trough _i_ there is a space _l_ into which
steam can be introduced through _f_, the condensed water passing away
by _g_.