Pressing and refining
Once refined it's meltingly subline.
When the ingredients such as milk powder, sugar, cocoa liquor etc. have been blended together in the mélangeur, the mixture this creates goes to be refined. This process is crucial to the later quality of the chocolate: whether it melts in the mouth or leaves a gritty feeling. Refining decides the particle size of the mixture: the chocolate fineness. This takes place in a two-part process.
In the first step, pre-refining, the particles of the mixture are squeezed under high pressure by two rollers rotating in opposite directions. Then comes the refining. Here, the mixture goes through five vertically aligned sets of heavy steel rollers. Hydraulic pressure moves them closer together so that the space between the rollers gets narrower and narrower as they go along. The temperature of each roller is controlled from inside using water cooling. When the finely pressed mixture comes out of the last set of rollers it is scraped off with a knife: a finely ground, flaky chocolate powder which is conveyed to the conches on belts. The entire refining process is of course constantly monitored to guarantee optimum results.
Generally, milk chocolate mass has to be refined at lower temperatures than dark chocolate mass. The same is true of most sugar-free chocolates. Incidentally, in England and the USA, chocolates are particularly popular that leave a slightly gritty feeling on the tongue: tastes differ.