To understand why van Houten's breakthrough was so important, here is a brief account of how the cocoa bean gets from the tree to the sweet cupboard.

The tropical cacao tree produces large pods, each containing 20-40 beans. The all-important "cocoa butter" accounts for about 50% of the bean. Immediately after harvesting the beans are removed from the pods and left to ferment for a few days - a process which removes some of their natural bitterness. They are then dried in the sun. After this they are normally exported for further processing.

Processing involves crushing the beans and removing the husks, and then roasting them. The next stage is grinding: this liquefies the cocoa butter in the beans and produces a thick paste, also known as "chocolate liquor". Some of the paste is kept back and the rest is pressed to remove more of the cocoa butter. (This is where van Houten's invention comes in.)

The manufacturer now has three ingredients for further processing:

I) Cocoa paste (containing some cocoa butter)
II) Cocoa butter
III) Cocoa cake (what is left of the paste after most of the butter has been pressed out) This is ground and sifted to make cocoa powder

Both plain and milk chocolate are made by mixing cocoa paste + cocoa butter + sugar + vanilla (or vanilla extract). Powdered milk is added for milk chocolate.

These ingredients are mixed and kneaded, to produce a paste, which is then rolled. This is following by conching, the continuous stirring of the paste, which liquefies the chocolate and gives it its final aroma and smooth texture.

The final product can be made by pouring, pressing, coating or moulding the liquid chocolate.