Chocolate spent most of its history as a bitter drink

A drink, and not a sweet one

Cacao was cultivated and consumed in Mesoamerica for thousands of years before Europeans encountered it, and the form it took there was a drink: beans fermented, dried, roasted and ground into a paste, mixed with water, and flavoured with chilli, vanilla, flowers and other aromatics. It was frothed by pouring between vessels, and the foam was prized. Sweetness was not part of the picture in the way we would expect.

Cacao beans also served as a unit of exchange in parts of Mesoamerica, which says something about how the crop was valued. When it reached Europe in the sixteenth century it remained a drink, and the main modification was the addition of sugar and the substitution of some spices for others. For roughly three hundred years after that, chocolate in Europe meant something you poured into a cup.

The obstacle was fat

Cacao beans are roughly half fat by weight. Ground cacao is therefore an extremely rich paste, and a drink made from it is greasy — historical preparations often had a layer of fat floating on top, and various thickeners and starches were used to hold it in suspension. This is also why solid eating chocolate did not simply appear: ground cacao mixed with sugar and set into a cake is gritty and fatty, and it does not have the texture anybody wants.

The nineteenth century solved this in stages, and each stage was an engineering problem rather than a culinary one. The first was a hydraulic press developed in the Netherlands in the 1820s, which squeezed a large part of the fat out of the ground cacao and left a pressed cake that could be milled into a fine powder. That powder made a much lighter drink. It also produced a by-product, cocoa butter, which turned out to matter more than the powder did.

Adding fat back is what made a bar possible

The insight that followed was to combine cocoa powder, sugar and additional cocoa butter into a mixture with more fat than the bean naturally contains. That extra fat is what allows a chocolate to be liquid enough to mould and to set into a solid that melts cleanly in the mouth rather than crumbling. Eating chocolate as a category dates from this idea, in the middle of the nineteenth century, and it depended entirely on the press that had made surplus cocoa butter available.

Milk chocolate arrived shortly afterwards and posed its own problem, since milk is mostly water and water and chocolate do not combine. The solution was condensed and then dried milk, which brought dairy solids without the water, and that work was done in Switzerland in the later part of the century. The distinctive flavour of milk chocolate comes substantially from how those milk solids are processed before they go in.

Conching, and the arrival of smoothness

The last major piece was conching: prolonged agitation and warming of the chocolate mass for many hours, developed in Switzerland in the 1870s. It reduces particle size and coats the particles evenly in fat, which is what takes a chocolate from gritty to smooth, and it drives off volatile acids left over from fermentation, which mellows the flavour considerably.

Once conching existed, the modern bar was essentially complete: refined to particles below the threshold at which the tongue detects them, tempered so that the cocoa butter sets in the right crystal form, and stable enough to sell. Everything since has been refinement of that process rather than a new idea. It is worth noticing how recent all this is — the chocolate most people picture is a nineteenth-century industrial product, not an ancient food.

What was lost and what came back

Industrial chocolate optimised for consistency, and it did so partly by roasting hard and conching long, both of which flatten the differences between beans. That was a reasonable choice for a mass product and it had a cost: the variation in flavour that comes from cacao variety, growing region and fermentation practice was largely engineered out.

The interest in single-origin chocolate and in shorter, gentler processing that has grown over recent decades is essentially an attempt to recover some of that. Whether the results justify the prices is contested and depends heavily on the individual maker. What is not contested is the underlying point: the flavour of chocolate is made in the fermentation heap and the roaster far more than in the moulding room, and the drink the Mesoamericans made was tasting something the nineteenth century decided to standardise away.