Stuff Matters: Exploring the Marvelous Materials That Shape Our Man-Made World

by Mark Miodownik

Dark chocolate usually contains 50 percent cocoa fat and 20 percent cocoa nut powder (referred to as “70 percent cocoa solids” on the packaging). Almost all the rest is sugar. Thirty percent sugar is a lot. It’s the equivalent of putting a spoonful of sugar in your mouth. Nevertheless dark chocolate isn’t overly sweet; sometimes it’s not sweet at all. This is because at the same time that the sugars are released by the melting cocoa butter, so are chemicals known as alkaloids and phenolics from the cocoa powder. These are molecules such as caffeine and theobromine, which are extremely bitter and astringent. They activate the bitter and sour taste receptors and complement the sweetness of the sugar. Balancing these basic tastes to give the chocolate a rounded flavor is the first task of the chocolatier. The addition of salt as a flavor enhancer, as well as adding another dimension to modern chocolates, has in turn led to chocolate being used as an ingredient in savory dishes: it is the basis of the Mexican dish pollo con mole, which is chicken cooked in dark chocolate.