THE MANUFACTURE OF COCOA AND CHOCOLATE
The Indians, from whom we borrow it, are not very nice in
doing it; they roast the kernels in earthen pots, then free
them from their skins, and afterwards crush and grind them
between two stones, and so form cakes of it with their hands.
_Natural History of Chocolate_, R. Brookes, 1730.
_Early Methods in the Tropics._
As the cacao bean is grown in tropical countries, it is there that we
must look for the first attempts at manufacturing from it a drink or a
foodstuff. The primitive method of preparation was very simple,
consisting in roasting the beans in a pot or on a shovel to develop
their flavour, winnowing in the wind, and then rubbing the broken
shelled beans between stones until quite fine. The curious thing is that
on grinding the cacao bean in the heat of a tropical day we do not
produce a powder but a paste. This is because half the cacao bean
consists of a fat which is liquid at 90° F., a temperature which is
reached in the shade in tropical countries. This paste was then made
into small rolls and put in a cool place to set. Thus was produced the
primitive unsweetened drinking chocolate. This is the method, which
Elizabethans, who ventured into the tangled forests of equatorial
America, found in use; and this is the method they brought home to
Europe. In the tropics these simple processes are followed to this day,
but in Europe they have undergone many elaborations and refinements.
If the reader will look at the illustration entitled "Women grinding
chocolate," he will see how the brittle roasted bean is reduced to a
paste in primitive manufacture. A stone, shaped like a rolling-pin, is
being pushed to and fro over a concave slab, on which the smashed beans
have already been reduced to a paste of a doughy consistency.
[Illustration: EARLY FACTORY METHODS.
Fig. 1 is a workman roasting the cacao in an iron kettle over a furnace.
He has to stir the beans to keep them from burning. Fig. 2 is a person
sifting and freeing the roasted kernels (which when broken into
fragments are called "_nibs_") from their husks or shell. Fig. 3 shows a
workman pounding the shell-free nibs in an iron mortar. Fig. 4
represents a workman grinding the nibs on a hard smooth stone with an
iron roller. The grinding is performed over a chafing-dish of burning
charcoal, as it is necessary, for ease of grinding, to keep the paste in
a liquid condition.]
_Early European Manufacture._
The conversion of these small scale operations into the early factory
process is well shown in the plate which I reproduce above from _Arts
and Sciences_, published in 1768.
[Illustration: WOMEN GRINDING CHOCOLATE.
From Squier "Nicaragua"]
A certain atmosphere of dreamy intellectuality is associated with
coffee, so that the roasting of it is felt to be a romantic occupation.
The same poetic atmosphere surrounded the manufacture of drinking
chocolate in the early days: the writers who revealed the secrets of its
preparation were conscious that they were giving man a new æsthetic
delight and the subject is treated lovingly and lingeringly. One, Pietro
Metastasio, went so far as to write a "cantata" describing its
manufacture. He describes the grinding as being done by a vigorous man,
and truly, to grind by hand is a very laborious operation, which happily
in more recent times has been performed by the use of power-driven
mills.
Operations on a large scale followed the founding of Fry and Sons at
Bristol in 1728, and of Lombart, "la plus ancienne chocolaterie de
France," in Paris in 1760. In Germany the first chocolate factory was
erected at Steinhunde in 1756, under the patronage of Prince Wilhelm,
whilst in America the well-known firm of Walter Baker and Co. began in a
small way in 1765. From the methods adopted in these factories have
gradually developed the modern processes which I am about to describe.
MODERN PRACTICE.
As the early stages in the manufacture of cocoa and of chocolate are
often identical, the processes which are common to both are first
described, and then some individual consideration is given to each.
(_a_) _Arrival at the Factory._
The cacao is largely stored in warehouses, from which it is removed as
required. It has remarkable keeping properties, and can be kept in a
good store for several years without loss of quality. Samples of cacao
beans in glass bottles have been found to be in perfect condition after
thirty years. Some factories have stores in which stand thousands of
bags of cacao drawn from many ports round the equator. There is
something very pleasing about huge stacks of bags of cacao seen against
the luminous white walls of a well-lighted store. The symmetry of their
construction, and the continued repetition of the same form, are never
better shown than when the men, climbing up the sides of a stack against
which they look small, unbuild the mighty heap, the bags falling on to a
continuous band which carries them jauntily out of the store.
[Illustration: PART OF A CACAO BEAN WAREHOUSE, SHOWING ENDLESS BAND
CONVEYOR.
(Messrs. Cadbury Bros'. Works, Bournville).]
(_b_) _Sorting the Beans._
As all cacao is liable to contain a little free shell, dried pulp (often
taken for twigs), threads of sacking and other foreign matter, it is
very carefully sieved and sorted before passing on to the roasting
shop. In this process curios are occasionally separated, such as palm
kernels, cowrie shells, shea butter nuts, good luck seeds and "crab's
eyes." The essential part of one type of machine (_see illustration_)
which accomplishes this sorting is an inclined revolving cylinder of
wire gauze along which the beans pass. The cylinder forms a continuous
set of sieves of different sized mesh, one sieve allowing only sand to
pass, another only very small beans or fragments of beans, and finally
one holding back anything larger than single beans (_e.g._, "cobs," that
is, a collection of two or more beans stuck together).
[Illustration: CACAO BEAN SORTING AND CLEANING MACHINE.
Reproduced by permission of Messrs. J. Baker & Sons, Ltd., Willesden.]
Another type of cleaning machine is illustrated by the diagram on the
opposite page.
This machine with its shaking sieves and blast of air makes a great
clatter and fuss. It produces, however, what the manufacturers desire--a
clean bean sorted to size.
[Illustration: DIAGRAM OF CACAO BEAN CLEANING MACHINE.
This is a box fitted with shaking sieves down which the cacao beans pass
in a current of air. Having come over some large and very powerful
magnets, which take out any nails or fragments of iron, they fall on to
a sieve (1/4-inch holes) which the engineer describes as "rapidly
reciprocating and arranged on a slight incline and mounted on spring
bars." This allows grit to pass through. The beans then roll down a
plane on to a sieve (3/8-inch holes) which separates the broken beans,
and finally on to a sieve with oblong holes which allows the beans to
fall through whilst retaining the clusters. The beans encounter a strong
blast of air which brushes from them any shell or dust clinging to
them.]
(_c_) _Roasting the Beans._
As with coffee so with cacao, the characteristic flavour and aroma are
only developed on roasting. Messrs. Bainbridge and Davies (chemists to
Messrs. Rowntree) have shown that the aroma of cacao is chiefly due to
an amazingly minute quantity (0.0006 per cent.) of linalool, a
colourless liquid with a powerful fragrant odour, a modification of
which occurs in bergamot, coriander and lavender. Everyone notices the
aromatic odour which permeates the atmosphere round a chocolate
factory. This odour is a bye-product of the roasting shop; possibly some
day an enterprising chemist will prevent its escape or capture it, and
sell it in bottles for flavouring confectionery, but for the present it
serves only to announce in an appetising way the presence of a cocoa or
chocolate works.
[Illustration: SECTION THROUGH GAS HEATED CACAO ROASTER.]
Roasting is a delicate operation requiring experience and discretion.
Even in these days of scientific management it remains as much an art as
a science. It is conducted in revolving drums to ensure constant
agitation, the drums being heated either over coke fires or by gas. Less
frequently the heating is effected by a hot blast of air or by having
inside the drum a number of pipes containing super-heated steam.
[Illustration: ROASTING CACAO BEANS.
(Messrs. Cadbury Bros'. Works, Bournville).]
The diagram and photo show one of the types of roasting machines used
at Bournville. It resembles an ordinary coffee roaster, the beans being
fed in through a hopper and heated by gas in the slowly revolving
cylinder. The beans can be heard lightly tumbling one over the other,
and the aroma round the roaster increases in fullness as they get hotter
and hotter. The temperature which the beans reach in ordinary roasting
is not very high, varying round 135° C. (275° F), and the average period
of roasting is about one hour. The amount of loss of weight on roasting
is considerable (some seven or eight per cent.), and varies with the
amount of moisture present in the raw beans.
There have been attempts to replace the æsthetic judgment of man, as to
the point at which to stop roasting, by scientific machinery. One rather
interesting machine was so devised that the cacao roasting drum was
fitted with a sort of steelyard, and this, when the loss of weight due
to roasting had reached a certain amount, swung over and rang a bell,
indicating dramatically that the roasting was finished. As beans vary
amongst other things in the percentage of moisture which they contain,
the machine has not replaced the experienced operator. He takes samples
from the drum from time to time, and when the aroma has the character
desired, the beans are rapidly discharged into a trolley with a
perforated bottom, which is brought over a cold current of air. The
object of this refinement is to stop the roasting instantly and prevent
even a suspicion of burning.
After roasting, the shell is brittle and quite free from the cotyledons
or kernel. The kernel has become glossy and friable and chocolate brown
in colour, and it crushes readily between the fingers into small angular
fragments (the "nibs" of commerce), giving off during the breaking down
a rich warm odour of chocolate.
(_d_) _Removing the Shells._
It has been stated (see _Fatty Foods_, by Revis and Bolton) that it was
formerly the practice not to remove the shell. This is incorrect, the
more usual practice from the earliest times has been to remove the
shells, though not so completely as they are removed by the efficient
machinery of to-day.
[Illustration: CACAO BEAN, SHELL AND GERM.]
In _A Curious Treatise on the Nature and Quality of Chocolate_, by
Antonio Colmenero de Ledesma (1685), we read: "And if you peel the
cacao, and take it out of its little shell, the drink thereof will be
more dainty and delicious." Willoughby, in his _Travels in Spain_,
(1664), writes: "They first toast the berries to get off the husk," and
R. Brookes, in the _Natural History of Chocolate_ (1730), says: "The
Indians ... roast the kernels in earthen pots, then free them from their
skins, and afterwards crush and grind them between two stones."
He further definitely recommends that the beans "be roasted enough to
have their skins come off easily, which should be done one by one,
laying them apart ... for these skins being left among the chocolate,
will not dissolve in any liquor, nor even in the stomach, and fall to
the bottom of the chocolate-cups as if the kernels had not been
cleaned."
That the "Indian" practice of removing the shells was followed from the
commencement of the industry in England, is shown by the old plate which
we have reproduced on p. 120 from _Arts and Sciences_.
The removal of the shell, which in the raw condition is tough and
adheres to the kernel, is greatly facilitated by roasting. If we place a
roasted bean in the palm of the hand and press it with the thumb, the
whole cracks up into crisp pieces. It is now quite easy to blow away the
thin pieces of shell because they offer a greater surface to the air and
are lighter than the compact little lumps or "nibs" which are left
behind. This illustrates the principle of all shelling or husking
machines.
(_e_) _Breaking the Bean into Fragments._
The problem is to break down the bean to just the right size. The pieces
must be sufficiently small to allow the nib and shell readily to part
company, but it is important to remember that the smaller the pieces of
shell and nib, the less efficient will the winnowing be, and it is usual
to break the beans whilst they are still warm to avoid producing
particles of extreme fineness. The breaking down may be accomplished by
passing the beans through a pair of rollers at such a distance apart
that the bean is cracked without being crushed. Or it may be effected in
other ways, _e.g._, by the use of an adjustable serrated cone revolving
in a serrated conical case. In the diagram they are called kibbling
cones.
[Illustration: SECTION THROUGH KIBBLING CONES AND GERM SCREENS.]
(_f_) _Separating the Germs._
About one per cent. of the cacao bean fragments consists of "germs." The
"germ" is the radicle of the cacao seed, or that part of the cacao seed
which on germination forms the root. The germs are small and rod-shaped,
and being very hard are generally assumed to be less digestible than the
nib. They are separated by being passed through revolving gauze drums,
the holes in which are the same size and shape as the germs, so that the
germs pass through whilst the nib is retained. If a freakish carpenter
were to try separating shop-floor sweepings, consisting of a jumble of
chunks of wood (nib), shavings (shell) and nails (germ) by sieving
through a grid-iron, he would find that not only the nails passed
through but also some sawdust and fine shavings. So in the above machine
the finer nib and shell pass through with the germ. This germ mixture,
known as "smalls" is dealt with in a special machine, whilst the larger
nib and shell are conveyed to the chief winnowing machine. In this
machine the mixture is first sorted according to size and then the nib
and shell separated from one another. The mixture is passed down long
revolving cylindrical sieves and encounters a larger and larger mesh as
it proceeds, and thus becomes sieved into various sizes. The separation
of the shell from the nib is now effected by a powerful current of air,
the large nib falling against the current, whilst the shell is carried
with it and drops into another compartment. It is amusing to stand and
watch the continuous stream of nibs rushing down, like hail in a storm,
into the screw conveyor.
[Illustration: SECTION THROUGH WINNOWING MACHINE.]
This is the process in essence--to follow the various partially
separated mixtures of shell and nib through the several further
separating machines would be tedious; it is sufficient for the reader
to know that after the most elaborate precautions have been taken the
nib still contains about one per cent. of shell, and that the nib
obtained is only 78.5 per cent. of the weight of raw beans originally
taken. Most of the larger makers of cocoa produce nib containing less
than two per cent. of shell, a standard which can only be maintained by
continuous vigilance.
[Illustration: CACAO GRINDING.
A battery of horizontal grinding mills, by which the cacao nibs are
ground to paste (Messrs. Cadbury Bros., Bournville.)]
The shell, the only waste material of any importance produced in a
chocolate factory, goes straight into sacks ready for sale. The pure
cacao nibs (once an important article of commerce) proceed to the
blenders and thence to the grinding mill.
(_g_) _Blending._
We have seen that the beans are roasted separately according to their
kind and country so as to develop in each its characteristic flavour.
The pure nib is now blended in proportions which are carefully chosen to
attain the result desired.
(_h_) _Grinding the Cacao Nibs to Produce Mass._
In this process, by the mere act of grinding, the miracle is performed
of converting the brittle fragments of the cacao bean into a
chocolate-coloured fluid. Half of the cacao bean is fat, and the
grinding breaks up the cells and liberates the fat, which at blood heat
melts to an oil. Any of the various machines used in the industries for
grinding might be used, but a special type of mill has been devised for
the purpose.
In the grinding room of a cocoa factory one becomes almost hypnotised by
a hundred of these circular mill-stones that rotate incessantly day and
night. In Messrs. Fry's factory the "giddy motion of the whirling mill"
is very much increased by a number of magnificent horizontal driving
wheels, each some 20 feet in diameter, which form, as it were, a
revolving ceiling to the room. Your fascinated gaze beholds "two or
three vast circles, that have their revolving satellites like moons,
each on its own axis, and each governed by master wheels. Watch them for
any length of time and you might find yourself presently going round and
round with them until you whirled yourself out of existence, like the
gyrating maiden in the fairy tale."
In this type of grinding machine one mill stone rotates on a fixed
stone. The cacao nib falls from a hopper through a hole in the centre of
the upper stone and, owing to the manner in which grooves are cut in the
two surfaces in contact, is gradually dragged between the stones. The
grooves are so cut in the two stones that they point in opposite
directions, and as the one stone revolves on the other, a slicing or
shearing action is produced. The friction, due to the slicing and
shearing of the nib, keeps the stones hot, and they become sufficiently
warm to melt the fat in the ground nib, so that there oozes from the
outer edge of the bottom or fixed stone a more or less viscous liquid or
paste. This finely ground nib is known as "mass." It is simply liquified
cacao bean, and solidifies on cooling to a chocolate coloured block.
[Illustration: SECTION THROUGH GRINDING STONES.]
This "mass" may be used for the production of either cocoa or chocolate.
When part of the fat (cacao butter) is _taken away_ the residue may be
made to yield cocoa. When sugar and cacao butter are _added_ it yields
eating chocolate. Thus the two industries are seen to be
inter-dependent, the cacao butter which is pressed out of the mass in
the manufacture of cocoa being used up in the production of chocolate.
The manufacture of cocoa will first be considered.
(_i_) _Pressing out the excess of Butter._
The liquified cacao bean or "mass," simply mixed with sugar and cooled
until it becomes a hard cake, has been used by the British Navy for a
hundred years or more for the preparation of Jack's cup of cocoa. It
produces a fine rich drink much appreciated by our hardy seamen, but it
is somewhat too fatty to mix evenly with water, and too rich to be
suitable for those with delicate digestions. Hence for the ordinary
cocoa of commerce it is usual to remove a portion of this fat.
[Illustration: A CACAO PRESS.
Reproduced by permission of Messrs. Lake, Orr & Co., Ltd.]
If "mass" be put into a cloth and pressed, a golden oil (melted cacao
butter) oozes through the cloth. In practice this extraction of the
butter is done in various types of presses. In one of the most
frequently used types, the mass is poured into circular steel pots, the
top and bottom of which are loose perforated plates lined with felt
pads. A number of such pots are placed one above another, and then
rammed together by a powerful hydraulic ram. They look like the parts of
a slowly collapsing telescope. The "mass" is only gently pressed at
first, but as the butter flows away and the material in the pot becomes
stiffer, it is subjected to a gradually increasing pressure. The ram,
being under pressure supplied by pumps, pushes up with enormous force.
The steel pots have to be sufficiently strong to bear a great strain, as
the ram often exerts a pressure of 6,000 pounds per square inch. When
the required amount of butter has been pressed out, the pot is found to
contain not a paste, but a hard dry cake of compressed cocoa. The
liquified cacao bean put into the pots contains 54 to 55 per cent. of
butter, whilst the cocoa press-cake taken out usually contains only 25
to 30 per cent. The expressed butter flows away and is filtered and
solidified (see page 158). All that it is necessary to do to obtain
cocoa from the press cake is to powder it.
[Illustration: SECTION THROUGH CACAO PRESS-POT AND RAM-PLATE.]
(_j_) _Breaking Down the Press Cake to Cocoa Powder._
The slabs of press-cake are so hard and tough that if one were banged on
a man's head it would probably stun him. They are broken down in a
crushing mill, the inside of which is as full of terrible teeth as a
giant's mouth, until the fragments are small enough to grind on steel
rollers.
(_k_) _Sieving._
As fineness is a very important quality of cocoa, the powder so obtained
is very carefully sieved. This is effected by shaking the powder into an
inclined rotating drum which is covered with silk gauze. In the cocoa
which passes through this fine silk sieve, the average length of the
individual particles is about 0.001 inch, whilst in first-class
productions the size of the larger particles in the cocoa does not
average more than 0.002 inch. Indeed, the cocoa powder is so fine that
in spite of all precautions a certain amount always floats about in the
air of sieving rooms, and covers everything with a brown film.
(_l_) _Packing._
The cocoa powder is taken to the packing rooms. Here the tedious
weighing by hand has been replaced by ingenious machines, which deliver
with remarkable accuracy a definite weight of cocoa into the paper bag
which lines the tin. The tins are then labelled and packed in cases
ready for the grocer.