a communication from P. Welmans, reaches 1 Burstyn in the expressed
fat and amounts to 1·66 cc. in the extracted fat (no. of cc. of normal
potash solution to 100 grammes of fat).
[37] Dingler, Polytechnical Journal, Vol. 253, p. 281. For details of
the method compare also P. Welmans Zeitschrift für öffentl. Chemie,
1900, No. 5.
[38] Zeitschrift für anal. Chemie 1896, p. 519.
[39] Zeitschrift für öffentl. Chemie 1900, p. 95.
[40] Though Strohl Zeit. Analyt. Ch. 1896. Vol. 35. p. 166. has
obtained with a Bahia fat an iodine value of 41·7, possibly exception
due to some over-roasting of the beans or to their fat having been
extracted by a petroleum ether of very high boiling point. Cf. also
table 12.
[41] Zeitschr. Analyt. Chem. B. 21. p. 394.
[42] Correspondence of the Association of German Chocolate
Manufacturers.
[43] Zeitschrift für angew. Chem. 1898, p. 116.
[44] We are indebted for this table to the kindness of Dr. Fritsche,
Superintendent Meat Inspector at Cleves (Cf. also table of experiments
of Matthes & Müller, loc. cit p.—et seq.).
[45] Benedikt-Ulzer, Analyse der Fett-und Wachsarten. 5th. edition.
1908. p. 840. also Literature.
[46] These high percentages of acid may also be caused by the high
percentage of benzine used in the production.
[47] A. Ruffin, Pharmaceutische Rundschau 1899, No. 51, p. 820.
[48] Therapeutische Monatshefte. 1895. p. 345 and following pages.
[49] Compt. rendus de l’aced. des sciences de Paris, Vol. 123, p. 587.
[50] Apotheker-Zeitung 1892, p. 469 and Deutsche Vierteljahrsschrift
für öffentl. Gesundheitspflege 1893, No. 3.
[51] Pharmaceut. Zeitung 1898, p. 389.
[52] Hilger and Lazarus, Compare also Schweitzer, Pharmaceut. Zeitg.
1898, p. 389.
[53] Ann. d. Chem. and Pharm. 1841, Vol. 41, p. 125.
[54] Ibid. Bd. 118, pag. 151.
[55] Berliner Chemische Berichte 1897, pag. 1839.
[56] Archiv f. experiment. Pathol. u. Pharmacol. 1895, Vol. 35, pag.
449.
[57] Ibid. 1896, Vol. 30, pag. 53.
[58] Ibid. 1896, Vol. 36, pag. 66.
[59] Ibid. 1888, Vol. 24, p. 101.
[60] Therapeut. Monatshefte 1890, p. 10.
[61] Semaine médicale 1893, p. 366.
[62] Pharmaceut. Centralhalle 1898, p. 901.
[63] Dekker (Swiss Weekly Journal, Chem. a. Pharm.) 40, p. 436, 441,
451 u. 463 gives the following figures at 15 ° C.: Water 1800 parts,
spirits 1600, pure alcohol 3570, chloroform 3845, ether 25000, acetic
unit 3845, benzol 100000 and amylic alcohol 1250.
[64] See before.
[65] Journal de Pharmacie et de Chimie 1898, p. 176.
[66] Ibidem 1897, p. 329.
[67] Zeitschrift für analytische Chemie, Vol. 18, p. 346.
[68] Aleuron granules were first microscopically observed by H. Molisch
(Grundriß einer Histochemie d. pflanzl. Genßmittel in the cellular
tissue of the cacao bean. They are very similar to the starch granules
of the bean and contain within them a relatively large globoid lime and
magnesium phosphates associated with an organic substance (sugar) which
becomes visible in the form of globules when a section is incinerated.
[69] Zeitschrift für physiologische Chemie, Vol. 11, p. 207-232.
[70] Hygienische Rundschau. 1900. p. 314 & 315.
[71] E. S. Bastin, American Journal of Pharmacy 1894, p. 369.
[72] Chemischer technischer Centralanzeiger 1886, No. 53, p. 777.
[73] Contributions to the establishment of a rational feeding of
ruminants. So-called Weender’sche Beiträge, 1864 Number, p. 48 and also
Landwirtsch. Versuchsstationen, Vol. 6, p. 497.
[74] Zeitschrift für angewandte Chemie 1896, p. 712 und 749.
[75] Zeitschrift für Untersuchung von Nahrungs-und Genußmittel. 1898.
p. 3.
[76] Zeitschrift für öffentliche Chemie 1900, p. 223.
[77] Pharmaceutische Zeitung 1898, p. 390.
[78] Archiv der Pharmacie 1860, Vol. 153, p. 59.
[79] Beitrag zur pharmak. und chem. Kenntnis des Cacaos.
Inaug.-Dissertation Dorpat 1875.
[80] Untersuchungen über Kakao und dessen Präparate, 1887.
[81] Jahresbericht über die Fortschritte der Pharmacognosie etc. 1883,
p. 314.
[82] Archive der Pharmacie 1893, Vol. 231, p. 694.
[83] Zeitschrift des allgem. öster. Apoth.-Vereins 1898, p. 434.
[84] Repert. f. anal. Chemie 1885, Vol. 5, p. 178; cf. also the
investigations of Mathes & Müller.
[85] Grundriß einer Histochemie der pflanzl. Genußmittel, p. 22.
[86] Bulletin de la société chimique Paris 1872, p. 33.
[87] Pharmaceut. Zeitung Vol. 24, p. 243.
[88] Journ. de Pharm. et de Chim. 1883, Ser. V, Vol. 7, p. 506.
[89] König, Die menschlichen Nahrungs-und Genußmittel, Vol. 1, p. 261.
[90] Zipperer, Untersuchungen über Cacao und dessen Präparate, p. 55.
[91] Zeitschr. für Untersuchung von Nahrungs-u. Genußmitteln 1898, No.
[92] Repertorium der analyt. Chemie 1885, Vol. 5, p. 178.
[93] Compare Matthes & Müller, Z. U. N. 1906, Vol. 12, p. 90 et seq.
[94] Almost a tenth part of the ash of the shells consists of silica.
[95] cf. Moeller Mikroskopie der Nahrungs-und Genußmittel. Berlin.
1905. II part Springer p. 412.
[96] Ztschr. öffentl. Ch. 1899, p. 27.
[97] German patent No. 71, 373, 8th. January 1873.
[98] Engl. Patent No. 14624, June 16th. 1897.
[99] Pharm. Rundschau 1898, p. 781.
[100] Ztschr. für chemische Industrie 1878, p. 303, German Patent No.
2112, Sept. 24th. 1878.
[101] Annales de Chimie et de Physique, Vol. 183, p. 423.
[102] Zeitschrift für Pferdekunde und Pferdezucht 1888, No. 7. Nowadays
cacao shells are often added to fodder.
[103] Quoted by Filsinger Zeitschr. f. öffentl. Chemie 1899, p. 27.
[104] Communication from the Assoc. German Choc. Manufacturers, 19th.
year, No. 7.
+Part II.+
The Manufacture of Cacao Preparations.
A. Manufacture of Chocolate.
The Preparation of the Cacao Beans.
Up to the end of the eighteenth century the manufacture of chocolate
was carried on entirely by hand, a method at once laborious and
inefficient. The workman used to kneel down on the ground, and crush
the beans in iron mortars. It was not until 1732[105] that Buisson
introduced the use of a bench and so rendered that inconvenient and
unwholesome practice unnecessary. Even to-day, the Chinese cooks on
the Philippine islands carry their chocolate “Factory” about with
them, in which the trestle is essential. It further comprises a small
marble mortar and warmed pestle, and by means of these utensils and
implements the hulled beans are pounded, and the triturated mass so
obtained spread out. It is then flavoured with sugar and spices. With
that exception, hand labour in the chocolate manufacture has since the
year 1778 been entirely displaced by machinery, when Doret exhibited
the first specimen before the medical faculty of Paris. According
to Belfort de la Roque,[106] a Genoese named Bozelly had already
constructed a mill by means of which he was able to prepare from six to
seven hundred pounds of chocolate daily, comparing favourably with the
thirty pound output yielded by hand labour. Pelletier[107], in 1819,
describes a machine for the mechanical preparation of chocolate of his
own construction, capable of doing the work of seven men. The machines
used in the chocolate manufacture have since that time been repeatedly
improved and re-constructed, although always with this one end in view,
namely to obtain a fine even cacao mass, and afterwards mix it as
thoroughly as possible with the other ingredients employed.
The first machines of the modern type were constructed by the Parisian
mechanic George Hermann (1801-1883) in the year 1830, to which inventor
we are indebted for the principle of fine grinding with varying
velocities, on which manufacture of chocolate is based to-day. There is
at the present time a rather large circle of manufacturers engaged in
the putting together of special machines for the preparation of cacao
and cacao products, chocolate apart.
Whether chocolate manufacture be carried out on a large or small scale,
it always involves the subjecting of the cacao bean to a regularly
succeeding series of operations, before the resulting product known
as “Chocolate” (in the strict commercial sense of the term) can be
obtained.
The respective operations succeed each other as follows:
I. ~Preparation of the Beans.~
1. ~Storing~, ~cleansing~ and ~sorting~ of raw beans.
2. ~Roasting~ the cleansed beans.
3. ~Crushing~, ~shelling~ and ~cleansing~ the roasted
bean (removing the radicles etc.)
4. ~Mixing~ different kinds of beans.
II. ~Production of the Cacao Mass.~
5. ~Grinding~ the beans till they yield a homogenous paste on
heating.
6. ~Mixture~ of the liquefied cacao mass with sugar, spices, etc.
7. ~Trituration~ by rollers.
III. ~Preparation~ of the resulting ~Chocolate~.
8. ~Extraction~ of ~air~, ~division~ and
~moulding~.
9. ~Cooling.~
10. ~Packing~ and ~storing~.
This represents the general course of manufacture, which we will now
proceed to describe in more detail, following the headings given above.
1. Preparation of the Beans.
1. ~Storing~, ~cleansing~ and ~sorting~.
Right up to the moment when they are to be used in the manufacture, the
raw cacao beans must be kept as originally packed, and stored in an
airy sun-lit room; although if they have accumulated moisture during
transport or sustained any manner of damage in harvesting, they should
then be emptied out of the sacks, spread out over the floor of such a
room as above described, and dried as effectively as possible. It has
also been recommended that such beans be washed with a dilute solution
of caustic potash (1 in 5000), and afterwards dried rapidly.
Unfermented beans, those damaged in the harvest, and those which have
received no proper fermentation, develop a greyish white colour with
occasional tints of violet and an unpleasant, bitter herbal flavour,
properties which unfortunately penetrate to the resulting cacao
products. Attempts have been made to meet this evil with a so-called
“Secondary Fermenting Gordian[108] proposes in this connection that the
beans be filled in water-butts, and steeped in warm water for at least
48 hours (so that obviously the butts must be kept in a warm room), at
the expiration of which time it can be poured off, and the beans dried
in a chamber heated to a temperature of between forty and fifty degrees
centigrade. There is said to ensue an appreciable improvement as to
flavour and colour, when this process is carried out.
The magazines in which cacao beans are stored have sometimes an
unwelcome visitor, to wit, a grub which according to W. Hauswaldt[109]
happens to attack just the best kinds of Caracas and Trinidad. As
eggs of the grub have on several occasions been found on the interior
of the still unshelled bean, we may assume that they were deposited
by a butterfly (species unknown, but possibly Ephestia cahiriteller,
cf. von Faber loc. cit. page 335) either before or immediately after
fermentation, and no later. Sometimes these grubs appear on the surface
of the sacks, which they overspread in a few days. Removal of the
infected packages, opening the sacks, and exposure to the sun, as
well as a thorough cleansing of the storehouses, is attended with a
qualified amount of success. The best plan is to destroy the moths
during their period of activity in the summer months June, July, and
August.
According to Hauswaldt, Stollwerck[110] and G. Reinhardt[111], this
can be effected by placing in the store rooms large, shallow basins
of water, near which burning petroleum lamps are introduced on the
approach of dusk, favourably placed on a pile of bricks and stone, so
that they clearly illuminate the reflecting water. The moths assemble
round the light en masse and either perish in the water or flame, a
fate which sometimes overtakes even the larvae, for they display the
same fatal attraction for any light, real or apparent. The water must
be changed every day, as otherwise the wing-dust collecting on its
surface affords a means of escape to the insects coming later. As the
weather becomes cooler, the doors and windows of the store-rooms should
be left open, so that when frost sets in, the rest of the maggots may
be destroyed.
The cleansing and sorting of the raw cacao bean is the most important
factor in the manufacture of chocolate, and yield a manifold return,
for inferior and cheaper kinds of bean which have passed through these
processes can be advantageously mixed with finer varieties. The chief
object of cleansing and sorting is the removal of foreign bodies and
such chance admixtures as sand, pebbles, and fragments of sacking,
which are liable to damage the stones used in grinding at a later stage
of the preparation, or communicate an unnatural and disagreeable smell
to the subsequent roast products. These admixtures are so multiform and
various that they cannot be removed solely by the aid of machinery, but
must be finally picked out by hand. Mechanical appliances are limited
to the removal of pebbles, dust, and possible fragments of iron, after
which preliminary cleaning the beans are thrown on straps, where they
can be picked by hand. The collector of these foreign bodies would find
himself with a rather interesting stock at the end of a few years, as
Wilhelm Schütte-Felsche points out.
The cleansing of the raw beans was formerly carried out in so-called
roller casks, placed horizontally, and revolving round an axle fitted
in the floor, whence it passed upward, cutting them slantwise. In this
apparatus the beans were rolled and vigorously rubbed together, and
afterwards the hand-picking succeeded. More recently, the roller casks
have been displaced by rotary cylindrical sieves, driven by motor power.
Such a machine is illustrated in fig. 12. The beans are lifted to a
rotatory cylindrical sieve by means of an elevator, where they are
freed from dust and dirt; in other sections of the sieve fragments of
blossom, sacking, or cloth are isolated, whilst occasional splinters of
iron are removed by a large magnet. So prepared, the beans are cast on
running belts, and here the hand-picking above-mentioned is carried out.
Fig. 13 shows a cleansing machine for the same purpose, which has
recently become rather popular. Here the dust passing from the sieve
is sucked up into a dust chamber, by means of an exhauster, whilst
pebbles, blossom fragments, and small beans are separately isolated.
The cleansed beans pass likewise under magnetic influence, which
removes traces of iron, and finally succeed to the running belting.
Often the beans are introduced into an extensive brushing machine
before roasting, to cleanse them from dirt etc. These are generally
found in such factories as have circular and cylinder roasters with
direct heating apparatus. Fig. 13 a shows such a brushing machine for
cacao beans.
2. ~Roasting the Beans.~
The cleansed and sorted beans are now subjected to a high temperature,
that is to say, they are now roasted. This roasting answers many
purposes;
1. The aroma and flavour of the bean is so developed.
2. The starch granules are gelatinised.
3. The herbal constituents are so transformed that the flavour of the
beans becomes milder; a distinct improvement.
4. In the consequent drying, the shells are rendered brittle, and more
easily removeable.
5. The beans themselves can afterwards be better ground.
The roasting of the cacao bean does not demand so high a temperature
as that of coffee, to effect the above chemical and physical changes.
Experience has shown that the best temperature lies between 130-140 °
C., though deviations from this standard have recently become frequent
and considerable, according to the uses for which the cacaos are
intended, and roasting has sometimes taken place at a temperature even
as low as 100 ° C.
[Illustration: Fig. 12.]
The process of roasting can be carried out in the roasting drum or
machine in a variety of ways, as:
1. Direct roasting over a coal fire,
2. Passing of a hot-air stream over the beans,
[Illustration: Fig. 13.]
3. Roasting by means of gas, with compressed air, as far as ~sources
of heat~ are concerned; and as regards ~shape of the drum~, it
is to be noted that the cylindrical are most in use. The separation
of the shells from the kernel was still effected at the beginning of
the present century by stirring the beans in water and so detaching
the inner coating of the seeds, the method adopted by Weisched
(Mitscherlich page 112). Not till this stage had been reached were they
subjected to a strong heat, causing the shells to spring off.
This method has at the present time only historical interest, for the
so-called roasting drums, as used in the preparation of coffee, are now
universal.
[Illustration: Fig. 13a.]
Roasting must be attended with the greatest care, in order that it may
neither be too thorough nor insufficient. It is a great mistake to
think that the roasting machine can be handed over to the care of any
apprentice. That nicety of roasting which corresponds to the variety
and its subsequent utilisation constitutes the qualitative basis of
the chocolate manufactured later. It is impossible for even the best
chocolate maker to retrieve what has been spoilt in this important
preliminary operation, wherefore a skilled workman, endowed with a keen
sense of taste and smell, is always to be seen at the roasting machine.
It has already been attempted to provide a means of security against
over-burning by the construction of the so-called safety-roaster, about
which will be spoken later.
Overroasting is immediately indicated by a disagreeable empyreumatic
odour (resembling that of roasted coffee); the husks char and the
kernels crumble, also betraying a charring on the outside. There is
a correspondingly increasing keenness of flavour, and a transference
of theobromine from the kernel to the husks (cf. page 65). From the
destructive distillation of the cacao fat arises that volatile and
pungent acroleine which is the principal cause of the empyreuma of the
over-roasted bean.
[Illustration: Fig. 14.]
The following general precautions in roasting cacao are worthy of
note; 1. the beans should not remain too long in the roasting drum;
2. they should be kept on the stir, for which reason the apparatus is
made revolvable on its axles; 3. the heat applied should be carefully
regulated; and 4. to guard against a loss of aroma, the roasted beans
should be cooled as rapidly as possible.
As the cacao must be more or less roasted according to its quality and
ultimate destination, which entails the acquisition of considerable
empirical knowledge on the part of the workman entrusted with this
process, it would be neither advisable nor practicable to annex
definite instructions as to time and temperature requirements.
In the following we describe a machine which is to be found in most
factories and which corresponds to all the demands of technique.
From its heating system, it belongs to the class of hot-air current
roasters—direct coal fire assisting—and in shape to the cylindrical
roasters.
[Illustration: Fig. 14 a.]
This machine is illustrated in fig. 14 and shown in section in figs.
14 a and 14 b. To prevent loss of heat by radiation, to save fuel, and
preclude possibilities of danger from fire, the whole installation is
walled in. Driving shafts occur at the back of the machine, and the
charging apparatus is introduced in front. A furnace lies directly
under the drum, whilst on either side are chambers accessible to
currents of fresh air, which are provided with heating tubes and
which admit of a regulation of the air supply. They are shut off from
connection with the gases from the fire, so that only the fresh air
heated here can penetrate to the roasting products in the charged
drum. There are winnowing shovels fitted in this, calculated to keep
the beans in motion and facilitate the access of air. When the hopper
is closed, the gases arising from the roast product can be led off
by an annexed outlet pipe, and thereupon condensed and the resulting
liquid drained off at the foot of the machine. For the attainment of
the proper degree of roasting, as well as for controlling the whole
process, there is a sampler to every machine. The drum is emptied
whilst in motion, its door-like front being turned aside and the
roasted beans transferred by the winnowing shovels before mentioned to
trolleys wheeled underneath.
[Illustration: Fig. 14 b.]
The loss of heat by radiation is very insignificant, as the machine is
completely walled in. Any kind of fuel may be used. Since the stoking
as well as the removal of soot takes place at the front, several of
these roasters can be set up side by side. It is a great advantage
of this installation, that by removal of the front of the drum its
interior is laid quite open, admitting of a thorough overhauling which
is attended with every disadvantage for the flavour of subsequent
roasting lots.
The machine here described is constructed in varying sizes, with an
outside capacity of four hundred kilograms.
As already mentioned the so-called safety-roaster offers a certain
security against the burning of the beans as the roasting boiler is
lifted out of the fire by means of an automatically working safety
regulator. Figs. 15 a and b show a spherical roaster open and closed.
[Illustration: Fig. 15 a.]
The principal of construction is founded on the fact that each roasting
is connected with a loss of weight and it is logical that the same
quality of beans always yields the same loss of weight at a certain
degree of roasting. On an average cacao yields a loss of 6-7 %.
According to this, the loss of weight which can at first be empirically
ascertained, for example by a new kind of bean, can be calculated and
can be indicated on a regulator, on the principle of the Roman scale.
When the beans have lost the weight in question the counterpoise of
the regulator raises the axle of the roasting sphere by means of which
the working of the whole machine is set in motion.
There is no exception to the rule that only beans of one and the
same kind should be roasted and broken up together, as thickness or
thinness of the shells determines to a large extent the time required
for roasting, and also an even size of bean is necessary to the smooth
operation of the breaking machine. The husks of the roasted cacao bean
are hygroscopic, and consequently the roasted unshelled beans contain
more moisture after having been kept for a time, than they do in the
raw state; but the drier the bean is, the easier it shells. The cacao
is therefore to be worked up as quickly as possible, or at least kept
in well covered metal boxes till further treatment can be proceeded
with.
[Illustration: Fig. 15 b.]
As sources of heat we find direct and indirect stoking with house
coal and coal gas, and besides these, for the installations of larger
factories Dowson gas is especially suitable, as it does not involve
too high a temperature, and the outlay is not so great as when coal-gas
is used.
[Illustration: Fig. 16.]
The roasting machine in fig. 16 for Dowson or coal gas belongs to
the class of roasters with direct firing. It corresponds to the one
diagrammed in Fig. 15 as regards charging and emptying. Here also the
front wall of the drum can be removed, and the interior consequently
laid completely open. The transmission of gas is effected at an air
pressure of one atmosphere, for the attainment of which an air pump
is fitted up in the vicinity, capable of feeding four machines at the
same time. The drum holds about 150 kilos. It goes without saying that
the regulating of the requisite heat is in this instance of the utmost
ease and nicety. Another preponderating advantage of this machine as
compared with those heated with coke or ordinary coal is its clean
operation and the extraordinary speed with which it can be both started
and stopped. Form 3-4 cbm. of coal gas are needed for 100 kilos of
beans, whilst for Dowson gas, which has not such a high heating value,
much larger quantities are required, and consequently a stronger
framework becomes necessary, though here no air pumps need be put in
operation.
[Illustration: Fig. 17.]
Steam roasting apparatus have not proved particularly successful, as
has been evident in all experiments hitherto made with them, and steam
agency does not appear to be suitable for the cacao bean, it admitting
of no thorough and at the same time even roasting.