The flavour of chocolate starts with the genes of the cacao plant, but the notion of terroir – the soil and climate in which it is grown – is as crucial here as it is for wine.
As with wine, the flavour of the cacao bean relies on a fermentation process. After picking the football-shaped pods from the tree, the beans and surrounding fuzzy white pulp are scooped out and left in a pile to ferment for several days.
The chemicals produced, including ethanol, acetic acid and lactic acid, seep into the seed. Microbes also start breaking down bean storage proteins called vicillins into peptides and amino acids, which are crucial precursors to the chocolate flavour.
The exact chemical cocktail depends on the community of microbial chemists producing it. And that in turn depends on the terroir. It also depends on the genes of the chocolate bean.
Criollo beans favoured by artisan chocolatiers seem to need very little fermentation to produce their chemistry.
With roasting, these chemicals undergo further chemical reactions. Most important to the final flavour are the Maillard reactions between sugars and the amino acids released from the vicillin proteins.
Maillard reactions – the chemical reaction between amino acids and sugars – are responsible for browning foods and the delicious flavours that go with it, from toast to fried onions. In chocolate the “flavour-active” compounds produced include 80 types of pyrazines and more than 500 other compounds including hydrocarbons, alcohols, aldehydes, ketones, esters, amines, oxazoles, and sulphur compounds.
Finally the elaborate mixing process known as conching coats the particles of chocolate in a layer of fat, which improves the release of flavour and may also trigger more Maillard reactions.