Ingredients required for _plain eating-chocolate_.
Cacao nib or mass 33 parts. Cacao butter 13 " Sugar 53-3/4 " Flavouring 1/4 " ------------- 100 parts
Since eating-chocolate is produced by mixing sugar and cacao nib, with or without flavouring materials, and reducing to a fine homogeneous mass, the principles underlying its manufacture are obviously simple, yet when we come to consider the production of a modern high-class chocolate we find the processes involved are somewhat elaborate.
The nib is obtained in exactly the same way as in the manufacture of cocoa, the beans being cleaned, roasted and shelled. The roasting, however, is generally somewhat lighter for chocolate than for cocoa. The nibs produced may be used as they are, or they may be first ground to "mass" by means of mill-stones as described above.
Some makers use clear crystalline granulated sugar, others disintegrate loaf sugar to a beautiful snow-white flour. The nib, coarse or finely ground, is mixed with the sugar in a kind of edge-runner or grinding-mixer, called a _mélangeur_. As is seen in the photo, the _mélangeur_ consists of two heavy mill-stones which are supported on a granite floor. This floor revolves and causes the stationary mill-stones to rotate on their axes, so that although they run rapidly, like a man on a "joy wheel," they make no headway. The material is prevented from accumulating at the sides by curved scrapers, which gracefully deflect the stream of material to the part of the revolving floor which runs under the mill-stones. Thus the sugar and nib are mixed and crushed. As the mixture usually becomes like dough in consistency, it can be neatly removed from the _mélangeur_ with a shovel. The operator rests a shovel lightly on the revolving floor, and the material mounts into a heap upon it.
[Illustration: CHOCOLATE MELANGEUR. Reproduced by permission of Messrs. Lake. Orr & Coy. Ltd.]
[Illustration: PLAN OF CHOCOLATE MELANGEUR.]
[Illustration: CHOCOLATE REFINING MACHINE. Reproduced by permission of Messrs. J. Baker & Sons, Willesden.]
The mixture is now passed through a mill, which has been described as looking like a multiple mangle. The object of this is to break down the sugar and cacao to smaller particles. The rolls may be made either of granite (more strictly speaking, of quartz diorite) or of polished chilled cast iron. Chilled cast iron rolls have the advantage that they can be kept cool by having water flowing through them. A skilled operator is required to set the rolls in order that they may give a large and satisfactory output. The cylinders in contact run at different speeds, and, as will be seen in the diagram, the chocolate always clings to the roll which is revolving with the greater velocity, and is delivered from the rolls either as a curtain of chocolate or as a spray of chocolate powder. It is very striking to see the soft chocolate-coloured dough become, after merely passing between the rolls, a dry powder--the explanation is that the sugar having been more finely crushed now requires a greater quantity of cacao butter to lubricate it before the mixture can again become plastic. The chocolate in its various stages of manufacture, should be kept warm or it will solidify and much time and heat (and possibly temper) will be absorbed in remelting it; for this and other reasons most chocolate factories have a number of hot rooms, in which the chocolate is stored whilst waiting to pass on to the next operation. The dry powder coming from the rolls is either taken to a hot room, or at once mixed in a warm _mélangeur_, where curiously enough the whole becomes once again of the consistency of dough. The grinding between the rolls and the mixing in the _mélangeur_ are repeated any number of times until the chocolate is of the desired fineness. Whilst there are a few people who like the clean, hard feel of sugar crystals between the teeth, the present-day taste is all for very smooth and highly refined chocolate; hence the grinding operation is one of the most important in the factory, and is checked at the works at Bournville by measuring with a microscope the size of the particles. The cost of fine grinding is considerable, for whilst the first breaking down of the cacao nibs and sugar crystals is comparatively easy, it is found that as the particles of chocolate get finer the cost of further reduction increases by leaps and bounds. The chocolate may now proceed direct to the moulding rooms or it may first be conched.