Process for the Extraction or Rendering Soluble of Cocoa.
Year: 1895

page_text: COMPLETE SPECIFICATION.
Process for the Extraction or Rendering Soluble of Cocoa.
I, WILHELM GAEDKE of Hamburg-Eppendorf in the Empire of Germany,
Merchant, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
The processes hitherto employed for rendering cocoa soluble by means of alkalies
are based partly on the alkalies in a dried condition becoming mixed with the
cocoa after the roasting and shelling, during the grinding or after the grinding
whilst the cocoa material is in a heated state in a dissolved condition or on the
alkalies in solution being added to the raw beans or to the beans subjected to a
preliminary roasting, the cocoa beans being afterwards roasted at a higher
temperature (over 100 degrees C.) that is to say; subjected to the principal
roasting and afterwards ground.
By the treatment of the warmed cocoa material with alkalies according to the
first method, the alkalies act principally on the melted fat (cocoa butter forming up
to 55 per cent. of the contents of the beans) and to a less degree on the other nutritive
contents. The fat being melted out of the vegetable cells by the grinding and
heating, surrounds the remaining cocoa constituents and protects these more or
less from the influence of the alkalies.
In order to obtain a good solubility a correspondingly greater addition of
alkalies became necessary, which however affected to no inconsiderable extent the
color and taste of the cocoa.
In the latter case, that is by roasting the raw or preliminarily roasted beans
treated with alkalies according to the second method, the action of the alkalies by
means of the following roasting process may be too energetic by which certain
constituents of the cocoa undergo an excessive decomposition, diminishing the
nutritive value thereof.
If on the other hand the alkalies only act a short time on the raw cocoa beans,
it may happen that only the outer part, the shell and the layers immediately
thereunder are penetrated by the alkalies, and consequently certain parts of the
cocoa beans are too much, and other parts are too little affected.
Color, aroma and taste are thus influenced, especially the latter, because the
unpleasantly tasting constituents of the shell are imparted to the interior of the
beans.
The new process aims at the removal of the before-mentioned disadvantages with
the use of a smaller quantity of alkalies and involves the addition of alkalies after
the complete roasting of the beans and before they are ground (and before the
heating and liquefaction of the cocoa butter occurs).
The course of manufacture is as follows :-
After the raw cocoa beans have been freed by machines or hand brushing from
all extraneous matter they are completely roasted in a roasting machine of any
suitable construction at a suitable temperature (about 120° to 150° C.) so that the
moisture and empyreumatic gases are sufficiently driven off and a pleasant aromatic
smell and taste developed while the shells are loosened.
After the beans have cooled they are broken and shelled in the usual manner,
the crushing however being only carried so far as is absolutely necessary to permit
the removal of the shell and secure freedom from dust.
The clean fruit so obtained is then covered with such a quantity of a solution
of alkalies (caustic alkali, carbonate of alkalies, ammonia) as it can thoroughly
absorb.

page_text: The quantity of alkalies amounts according to the kind of bean, up to
two per cent. of the weight of the roasted and shelled beans. The quantity of
water in which the alkalies are dissolved also depends upon the kind of bean (as
one kind can take up more than other) and varies between twenty per cent. and
thirty per cent. of the weight of the roasted and shelled beans. In order to give an
example 100 kilogrammes of roasted and shelled beans would be moistened with
25 kilogrammes of water in which one kilogramme of carbonate of alkalies was
dissolved.
The uniform moistening of the pieces of bean may be obtained by any suitable
mechanical means. By preference 1 employ a vat having a steam jacket and
provided with a stirrer, or a steam-jacketted rotating drum.
If the fluid is added with a stirring of the beans it is advantageous to let it act
while cold for a time (say about an hour) on the beans with or without stirring,
so that these may be moistened through with the greatest possible uniformity.
The heating is then effected by means of the steam jacket, and with continual
stirring of the moistened beans, to a temperature below 100° C. (preferably 50°
to 70°).
When the desired temperature is reached the beans so prepared are placed in a
drying apparatus and dried at a temperature also not exceeding 100° C. and
preferably maintained at between 50° and 70° C.
The dried beans are then ground and the cocoa so obtained either used for
the manufacture of chocolate or pressed and further treated to obtain oil freed
cocoa.
The rendering soluble of the cocoa, as effected by the above described new
method is however not confined only to the employment of alkalies but may be
effected by the same process of manufacture with the use of water without any
addition of alkali.
A difference in the taste of the two products is however noticeable, for whilst
the cocoa prepared with alkalies shows an increase in the bitterness alongside with
the cocoa aroma, the cocoa prepared with pure water has a mild, slightly acid, but
strongly aromatic taste.
In treating the cocoa beans according to the process described, the hollow spaces
inside the beans, created during the roasting by the escape of empyreumatic gases,
and which spaces take the place of the cell walls, which are more or less destroyed,
become filled with the liquid employed and the latter spreads evenly through the
fully roasted beans, without its action on the organic constituents of the cocoa
beans not containing fat, being bindered by melted fat.
With the use of alkali solution as the moistening fluid, the alkalies can neither
produce too great a decomposition of the fat containing constituents nor create a
change into soap of the fat, as the temperature does not exceed 100° C. In
particular by means of the process described, the combinations free from nitrogen
closely resembling taunic acid are made more easily soluble and the fluid acids
contained in the cocoa beans are neutralised. Furthermore the non-volatile acids
arising from the partial decomposition during roasting of the tannic acid, are
chemically bound by the alkalies. If on the other hand water, without the
addition of alkalies is used in the preparation the volatile acids are driven off with
the water vapour on heating, whilst the non-volatile acids remain as such in the
product.
By this process a better chemical solubility of the organic constituents existing
alongside of the fat in the cocoa-bean is obtained, 18 to 22 per cent, water-soluble
constituents are produced, whilst in Dutch prepared cocoas in spite of the use of
three to four per cent. of alkalies, only twelve to fifteen per cent. is found. More
over a more advantageous mechanical solubility is at the same time obtained.
Under the latter title being understood the more general distribution of the
constituent parts, so desirable in the preparation of cocoa for drinking, and the
separation of the cocoa into a thin fluid and thick deposit takes place as slowly as
possible.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
An improved process for the rendering soluble of cocoa distinguished by the full
roasted and shelled cocoa-beans being moistened before grinding with a small
quantity (say up to two per cent.) of alkalies, (caustic alkali, carbonate of alkalies,
ammonia) dissolved in water in the proportion of at least twenty per cent. of
the weight of the beans or with water without alkalies, the cocoa being then
warmed and dried without further roasting, the temperature employed not
exceeding 100° Centigrade as herein described and set forth.
Dated this 12th dox of February 1805
S. S. BROMHEAD,
97, Newgate Street, London, E.C., Patent Agent.
S. S. BROMHEAD,
97, Newgate Street, London, E.C., Patent Agent.