perfected. The most practical arrangements for pulverising all kinds
of granulated sugar and so-called lump sugar, are those combined
grinding and sifting installations such as are executed by the
firm of J. M. Lehmann in Dresden. The grinding is here effected by
disintegrators (revolving arms, etc.) similar to those used in the
pulverising of cocoa powder as described on page 212. The output of
these disintegrators[138] is extraordinarily large, and the harder and
drier the ground sugar is, the finer the pulverised material resulting.
We annex a diagram of the machine in fig. 96.
[Illustration: Fig. 96.]
The granulated or lump sugar is filled into the hopper and thence lead
along a conveyor to be ground in another part of the machine, and can
be controlled as regards quantity. The blades, which pass through about
3000 revolutions a minute, seize the sugar and swing it against the
ribbed walls of the mantle, after which it falls in smaller fragments
on a grater fitted in the under part of the apparatus. The sugar which
passes through the grating is now conducted by conveyor and elevator to
the sifting arrangement, whilst the rougher material is again whirled
round by the blades. This sifting arrangement consists of a cylindrical
sieve, on the interior of which there occur revolving arms which
provide for the despatch of material through the various sieves. The
rougher stuff which remains is removed by hand or some other mechanical
means and transported to the hopper once more. A chamber placed above
the machine and connected with the grinding apparatus by means of pipes
provides for the protection of the machine against dust.
Such installations are constructed in various sizes and fashions, and
possess immense outputs (up to even 5000 kilogrammes daily). That they
must be built in special shops is clear from the fact that so large a
quantity of dusty sugar sacks need transporting after the processes are
completed. It is further to be noted that the fineness of the sugar
corresponds to the mesh-work of the sieves, which as we have previously
stated, can be chosen with any size of hole desired, yet this naturally
influences the machine, and recently a very high standard of fineness
has been generally dropped, and rougher siftings are now made, as when
the sugar is too fine.—e. g. in the case of the cheaper qualities—it
absorbs too much of the fatty contents, and so necessitates the
addition of cacao butter, whilst on the other hand, when the chocolate
is of a finer quality, the sugar is sufficiently reduced in the
trituration to which the mixed material is subjected.
b) Saccharin and other sweetening agents.
Apart from the sugar, which is such an important factor in the
chocolate manufacture, mention must also be made of another sweetening
material, formerly frequently used as a substitute for sugar, but now
only to be obtained at the apothecary’s on exhibition of a medical
order, in consequence of certain legal restrictions which have recently
come in force. It is called Fahlberg saccharin, and again zuckerin,
sykorin, crystallose, “Süßstoss Höchst” and sykose.
Saccharin is not like sugar a carbohydrate naturally produced by
plants, but a derivative of the aromatic compounds which the chemist
has artificially constructed from the products of the distillation of
coal.
Saccharin is benzoyl-sulphonimide, and it has the chemical formula
/ CO \
C_{6}H_{4}< >NH
\SO_{2}/
It is a white, crystalline powder, so exceedingly sweet that its taste
can be perceived in a dilution of 1 in 70000. It is only slightly
soluble in cold water (1: 400) but more easily so in hot water (1: 28).
The material known as easily soluble saccharin is its sodium salt. It
contains 90 percent of saccharin and is the most easily digested
compound of saccharin.
For technical, domestic and medicinal purposes the soluble saccharin
which is only from 300-450 times as sweet as sugar is employed.
Besides being unfermentable saccharin has very slight antiseptic
properties; according to L. Nencki[139] the digestibility of albumin
is less affected by it, in the proportion usually added to articles of
food, than by Rhine wine, or by a sugar solution of equal sweetness.
Saccharin is entirely unaltered in the human organism, hence it forms
a welcome sweetening material for invalids suffering from diabetes,
corpulence or diseases of the stomach to whom ordinary sugar is
injurious. The substances known as dulcin and glucin are analogous to
saccharin in sweetening property, the first being phenetol-carbamid and
the latter a monosulphonate of amido-triazine.
The latest substance of this class is termed “sucramin” and consists of
the ammonium salt of saccharin. It is readily soluble in water, less
so in alcohol and is 700 times sweeter than sugar. It can be obtained
either in the pure form or mixed (20 percent) with sugar.
In chocolate making, saccharin is at present of little importance,
owing to the relatively small volume required as compared with sugar.
Recently it has again been recommended to the extent of 0·76 percent
as a sweetening material for cocoa powder. It would certainly be of
value in cocoa powders to be consumed by invalids and persons not
able to take sugar, although it will never come into general use. The
detection of saccharin has acquired increased importance in Germany
since the passing of the acts of October 1st 1898 and July 7th 1902,
regulating the trade in artificial sweetening materials. According to
Zipperer’s experiments, it may be detected in the following manner:
A mixture of 5 grammes of the finely powdered substance with 100 ccm
of water is allowed to stand for 2 hours, occasionally stirred and
afterwards filtered. The filtrate is acidulated with three drops of
hydrochloric acid and evaporated to 20 ccm, then shaken[140] with 50
ccm of ether in a separator and left standing for a day to separate
into two layers. The ether solution is separated and evaporated to
dryness in a beaker, the residue being mixed with 0·1 gramme of
resorcin and 4-5 drops of concentrated sulphuric acid[141] (Börnsteins
test). The mixture is then heated over a small Bunsen flame and the
melted material saturated with normal sodium hydrate. The appearance of
a strong fluorescence indicates the presence of saccharin. Saccharin
can also be easily recognised by the sweet taste of the ether residue.
II. Kinds of Starch, Flour.
The chief kinds of starch used in chocolate making are rice starch,
arrowroot, potato starch and wheat starch, occasionally also small
quantities of dextrine.
1. ~Potato starch or flour.~
Potato starch is a white or faintly yellowish powder in which single,
glistening granules can be seen by the naked eye. Under the microscope
the granules appear mostly single with evident striae, usually with
pointed ends containing the nucleus; they are also eccentric in
structure. This starch rarely contains fragments of tissue. It is
prepared by first treating finely divided pared potatoes with 1
percent. dilute sulphuric acid, then washing, drying and grinding the
starch.
2. ~Wheat starch.~
Wheat starch can be obtained either from crushed wheat or from wheaten
flour by treatment with water after the nitrogenous constituent,
gluten, has been separated by kneading. It amounts to about 60-70
percent of the grain. Under the microscope the granules appear to
differ considerably in size. They are distinguished from potato starch
by the nearly central hilum, surrounded by faintly marked concentric
striae, and again by the granules being more frequently adherent. Wheat
flour rather than the starch is generally used in chocolate making.
3. ~Dextrin.~
When starch is heated to between 200° and 210° C. it is converted
chiefly into dextrin or starch gum with a little sugar. Dextrin is
a white to yellowish and tasteless powder with a peculiar smell; it
differs from starch in being readily soluble in water. It gives a
reddish colour with an aqueous solution of iodine. Fehling’s solution
is unaffected by dextrin in the cold, but on long continued heating it
is reduced to red cuprous oxide.
4. ~Rice starch.~
Rice starch is obtained from inferior kinds of rice and from rice waste
by treatment with water. It appears under the microscope as small
granules or oval bodies of various sizes. According to their position
the granules always seem to be polygons,[142] formed by coalescence. It
is thus easily distinguished from the previously mentioned starches.
5. ~Arrowroot.~
Several kinds of starch, obtained from the tubers of various species of
plants are commercially known under this name.
1. West Indian arrowroot, from Maranta arundinacea, is a fine and
almost white powder. Under the microscope it always appears to consist
of pear or spindle-shaped granules with eccentric hilum.
2. East Indian arrowroot is obtained from various species of ginger
plants. It is a fine white powder and is seen under the microscope as
single granules with well marked eccentric hilum and closely stratified
at the spindle-shaped ends. It much resembles Guiana arrowroot, which
is obtained from varieties of Yam.
3. Queensland arrowroots from species of Cycas and Canna, appear
as flat, coarse and mostly single granules. They can be easily
distinguished from other kinds of starch by the large size of the
granules.
4. Brazil arrowroot, from the Manihot plants which belong to the order
of Euphorbiaceae. Under the microscope the granules appear compound,
the parts being of a drum or sugar loaf shape with many concentric
striae.
6. ~Chestnut meal.~
Chestnut or maron meal also comes under consideration in the chocolate
industry. The appearance of the starch granules is most characteristic.
They are partly single and partly composed of two individual granules.
The single granules, according to J. F. Hanausek[143], appear in such a
variety of forms as to defy a summarised description. Frequently they
occur oval, spindle, club, or flat kidney shaped, resembling those of
the leguminous family; but especially to be noticed is the triangular
contour of some granules, as well as some with projecting points.
The central nucleus and its cavity are generally distinct, but the
stratification is very slight or quite unrecognisable.
7. ~Bean meal.~
Of the leguminous meals that of beans is chiefly used as an adjunct
in cocoa powders and chocolate, sweetened with saccharin, on account
of its relatively large proportion of albuminous substance and small
amount of starch. The meal is generally obtained from the seed of the
common white bean. (Phaseolus vulgaris.) The starch granules under the
microscope appear oval or long kidney shaped, with distinct nucleus
cavities and furrows, as well as a distinctly marked stratification.
Their length averages from 0·033 to 0·05 mm. The meal has a
disagreeable leguminous taste when cooked, but that disappears when the
meal is slightly roasted.
8. ~Salep.~
Salep which is now very seldom used as an admixture to chocolate
(Rakahout of the Arabs)[144] is an amylaceous powder prepared from the
tubers of various kinds of orchids. Under the microscope salep appears
as fairly large translucent masses which consist of an agglomeration of
very delicate walled cells giving the starch reaction with iodine.
III. Spices.
a) General Introduction.
We cannot too strongly recommend the manufacturer to pulverise the
spices, e. g. cinnamon, cloves and the like, himself, for such as
are bought ready pulverised have frequently been adulterated with
admixtures of wood, flour or bark. This is the more essential as
sometimes pulverised cinnamon is distilled with steam to obtain
an extract of its ethyl oil, and then the residue, which is of
considerably inferior value as regards aroma, sold as genuine cinnamon
powder. Such adulteration can neither be demonstrated under the
microscope nor chemically, so that it is impossible to protect oneself
against them.
[Illustration: Fig. 97.]
The edge runner mill and sieving apparatus described in connection with
the pulverising of sugar also adapt themselves to reducing spices,
although generally other machines are used for this purpose, either
the well-known ball mills[145] consisting of a hollow spherical ball
revolving round its axle, inside which the spices are shaken, crushed
and completely pulverised by the action of a number of heavy metal
balls, or in other cases pulverising mills and stamping arrangements
proper.
[Illustration: Fig. 98.]
The following stamp arrangement, shown in fig. 97, is very practical
in the pulverisation of all manner of spices, and is driven by a
force of 1·5 H.P. The strong frame, which is walled in with iron, is
dust-proof. Whilst the stamper is being raised, the pots are revolved
round their axles, and so the substances to be pulverised are mixed
together. Other machines much used in pulverising are seen in fig. 94.
Another smaller pulverising mill is pictured in fig. 98. This machine
is adapted for a middle sized production. The grinding arrangement
in which the pulverising takes place is conically built and is made
completely of granite; the regulation is effected by means of a
working beam, the batting arm of which is fitted on to the upper part
of the apparatus. A sieving of the material to be pulverised does not
generally take place in this machine. For small production for example
for confectioners who manufacture chocolate also incidentally, one
can also use the machines pictured in the figs. 95 & 99, the method
of working of which may be at once understood. The different degrees
of fineness of the material to be pulverised are reached by passing
the powder through drum sieves of different widths of mesh and all the
sieves are set in motion at the same time by the machines.
Vanilla.
Only the most important features of the spice so valuable in chocolate
making will be noticed, since the characteristic aroma of the
true vanilla has been to a large extent supplanted in practice by
artificially prepared vanillin.
Vanilla is the fruit capsule of an orchid, ~Vanilla planifolia~,
which is generally cultivated with the cacao tree, as the same climate
and soil suit them equally. According to Möller, the shoots of the
vanilla are fastened to the cacao tree, on the bark of which they
soon strike root. The aerial roots and tendrils then put forth fleshy
leaves, in the axils of which arise large odourless and dull coloured
flowers which yield after a lapse of two years long thin capsules.
The capsules are filled with a transparent balsam, in which the black
seeds are imbedded. It is in the balsam that the vanillin, which
gives vanilla its unequalled aroma, is produced. The fresh gathered
vanilla fruit (see the investigations of W. Busse[146] contains no free
vanillin or merely an infinitesimal quantity.
[Illustration: Fig. 99.]
It is rather developed by subsequent treatment in which heat appears
to be necessary. Vanillin, like cocoa-red and theobromine, is formed
by the splitting up of a glucoside by fermentative action. In some
kinds of vanilla, piperonal, an aromatic body, which occurs in larger
quantities in ~Heliotropium europaeum~ and ~peruvianum~, has
also been observed.
The commercial kinds of vanilla come from Mexico, Tahiti, Réunion,
Mauritius, Mayotte, Seychelles, Ceylon and Java, which in 1891 produced
respectively:
Réunion (Bourbon) 50-65,000 kilos
Mexico 55,000 “
Mauritius 13-15,000 ”
Mayotte (Comoro Islands) 8-10,000 “
Seychelles 4- 6,000 ”
The best commercial kinds of vanilla come from Mexico, Bourbon, and
Mauritius, and command a higher price than the other kinds. The
quantity is gauged by the length (10-24 cm), and plumpness of the
pods. Fine quality is fatty and dark coloured, inferior quality is dry
and reddish. The outside of the pods in the Bourbon vanilla, contains
highly esteemed vanillin crystals, which are wanting in the Mexican
variety. Vanilla flowers in October and November, is gathered in the
following months of May, June, and July, and is prepared in October
and November. At the beginning of November the first instalment of the
new harvest arrives in Marseilles, which is the chief commercial place
for vanilla. The most important operation, in preparing vanilla is to
attain the proper degree of dryness. This is arrived at nowadays by the
use of calcium chloride. The pods are first placed in a metallic box
lined with wool which is placed in warm water so as to superficially
dry them; they are then transferred to a suitable constructed drying
closet containing calcium chloride and allowed to remain there for
20-30 days. 100 pounds of vanilla are reckoned to require 40 pounds
of calcium chloride. The great advantage of this process is that the
fruit, so dried, better retains its aroma.[147] Insufficiently dried
vanilla does not keep, but soon becomes mouldy, whilst overheated
vanilla keeps well, but is brittle, breaks easily and consequently has
little commercial value. Vanilla covered with mould (~Aspergillus
repens~ and ~Mucor circinelloides~) is sought to be improved
in various ways and is sold as of inferior quality.[148] It is worth
observing that those persons who in the course of business handle
vanilla show characteristic symptoms of poisoning. It affects the eyes
and nervous system and produces eruptions on the skin. The complaint,
however, is not of a dangerous nature, for the workmen quickly become
accustomed to vanilla so that, after recovering from the first attack,
they can resume work without risk to health.[149]
On account of its high price, vanilla is much subjected to
adulteration; either by an admixture of the more cumarin-smelling
vanillin (Pompona or La Guayra Vanilla [Vanilla Pompona Schieder])
or other less valuable vanilla fruit; sometimes pods that have been
deprived of vanillin by extraction with alcohol are used for that
purpose; their colour and appearance being restored by immersion in
tincture of benzoin and coating with crystals of benzoic acid, powdered
glass etc. In doubtful cases of adulteration the vanillin must be
quantitatively determined.
That can be done by W. Busse’s method[150], in which the vanilla is
extracted with ether in a Soxhlet’s apparatus. The extract is shaken
with a solution of sodium bisulphite, the vanillin then set free with
sulphuric acid and the disengaged sulphurous acid removed by a stream
of carbon dioxide. The vanillin is then shaken out with ether and
on evaporating off the ether, vanillin is left in a pure condition.
Busse found by this method in East African vanilla 2·10 percent of
vanillin, in the Ceylon 1·48 percent, and in the Tahiti variety
from 1·55 to 2·02 percent. In America the so-called vanilla extract,
instead of vanilla, is used and it lends itself to adulteration much
more easily than natural vanilla. William Hesse has given methods and
results obtained in the investigation of the extract.[151]
5. ~Vanillin.~
Vanilla in the chocolate industry has recently been almost entirely
superseded by the use of artificially prepared vanillin, which serves
as a complete substitute for the essential and valuable constituent
of vanilla. In comparing vanillin with vanilla, regard must be had to
the amount of vanillin in the latter, which may vary to the extent of
50 percent according to whether the vanilla was damp, dry, fresh or
stored. The finest kinds of vanilla seldom contain more than 2
percent. of vanillin and in many kinds it varies between 0·5 and 2·5
percent. It may also happen that vanilla with 0·5 to 1·0 percent may
be equally as fine in appearance as one of high percentage, hence the
aroma value must be taken into consideration. In addition to possessing
a uniform and permanent perfume vanillin is cheaper in price.
Vanillin occurs naturally not only in vanilla but also in very small
amount in certain kinds of raw sugar, in potato skins and in Siam
benzoin; it can be produced artificially from coniferin which is
obtained from pine wood, or by the oxidation of eugenol, a substance
contained in oil of cloves, from both of which Tiemann and W.
Haarmann[152] first prepared it in 1872. In the course of the last ten
years a number of processes have been discovered whereby vanillin can
be artificially produced. The reader who is interested in this subject
will find it fully discussed in a paper by J. Altschul in No. 51 of the
Pharmazeutische Centralhalle 1895.
The competition which arose through the processes of Haarmann and
Reimer of Holzminden and G. de Laire of Paris, whose products owing to
patent rights had controlled the market from the commencement, produced
a steady decrease in the price of vanillin.
The following table drawn up by J. Rouché[153] shows the revolution
in price which has occurred in this article and how, in the course of
time, a small business with large profits has been transformed into a
large business with small profits.
~The variation in the price of vanillin~:
Marks per Kilo.
=====+======+======+======+======+======+======+======
1876 | 1877 | 1878 | 1879 | 1881 | 1882 | 1884 | 1885
=====+======+======+======+======+======+======+======
7000 | 4000 | 2400 | 1600 | 1600 | 1600 | 900 | 900
+======+======+======+======+======+======+=====
| 1886 | 1888 | 1890 | 1892 | 1893 | 1895 | 1897
+======+======+======+======+======+======+=====
| 700 | 700 | 700 | 700 | 700 | 560 | 108
The chemical formula of vanillin is C_{6}H_{3}(OCH_{3}) (OH)CHO; it
melts between 82-83 ° C. and sublimes at 120 ° C. The colourless
four-sided crystals have a strong vanilla odour and taste, are
difficultly soluble in cold water, easily in hot water and very readily
soluble in alcohol.
Vanillin is much adulterated. Cumarin, the aromatic principle of the
melitot (~meliotus officinalis~) and of tonquin beans etc., can
be prepared cheaply and it is fraudulently used in large or small
quantity to imitate the vanillin aroma. A sample of vanillin bought
in Switzerland was found by Hefelmann[154] to contain 26 percent
of antifebrin. The American “vanilla crystals” consist of a mixture
of vanillin and antifebrin, or vanillin, cumarin and benzoic acid;
latterly that article is stated to consist only of cumarin, antifebrin
and sugar.
The melting point of genuine vanillin is a characteristic indication.
Admixtures of vanillic acid and antifebrin cause depression of the
melting point (4-8 ° C. according to the amount and character of the
two substances [Welmans])[155]. For the quantitative determination of
vanillin in mixtures, Welmans takes advantage of its behaviour towards
caustic alkalis, with which, like phenol, it forms compounds that are
easily soluble in water, but sparingly so in alcohol. The process is as
follows: 1 gramme of the substance is placed in a cylinder of 200 ccm
capacity with 25 ccm of alcohol, 25 ccm of approximately semi-normal
alcoholic potash and 2 or 3 drops of phenolphthalein solution and
agitated until completely dissolved. The excess of alkali is then
titrated with semi-normal hydrochloric acid, and, at the same time,
the strength of the alcoholic potash after adding 25 ccm of alcohol is
ascertained. The number of cubic centimetres consumed is multiplied by
0·076, the semifactor for vanillin. In the case of vanilla sugar, 10
grammes are treated with 50 ccm of water to dissolve the sugar, then
the alcoholic potash is added and the operation carried out as before
described.
1 gramme of vanillin requires 6: 58 ccm of normal potash (= 0·36842 g
KOH).
OCH_{3}
/
C_{6}H_{3}(OH) : KOH
\ CHO
152 : 56 ⚎ 1 : x
If cumarin is suspected to have been added to the vanillin it can be
detected and separated, according to Zipperer’s experiments, by the
method of W. H. Hess and A. B. Prescott.[156]
The substance is dissolved in ether and the solution shaken up with a
weak solution of ammonia. The vanillin will be found in the aqueous
layer in the form of an ammonium compound, whilst the cumarin will
be dissolved by the ether. The vanillin can be identified by the
sandal-wood oil reaction as described by Bonnema,[157] and the cumarin
can be determined by direct weighing.