The Anatomy of Chocolate

• To understand the graying effect, it's important first to grasp chocolate's structure. It's made from the beanlike seeds of an astringent tropical fruit, fermented and then roasted to create its signature complex flavors. The beans are ground to make a mass of raw chocolate, called cocoa liquor. This "liquor" can then be separated into two very different substances: the dry flavor compounds -- familiar to any baker as cocoa -- and a rich and complex set of fats, called cocoa butter. The cocoa gives chocolate its taste and color, while cocoa butter provides the signature richness and smooth, melting texture.

Finding a Balance

• The two components are often separated during processing and then recombined in varying percentages depending on the desired end result. For example, chocolate destined for candy bars and chocolate chips often contains little or no cocoa butter, replacing it with lower-cost fats such as vegetable-oil shortening. Milk chocolate adds richness through dairy products and added sugar; it also needs little cocoa butter. Good-quality dark chocolate has high levels of cocoa butter, and couverture -- the high-grade chocolate used by pastry chefs -- adds even more, to make a chocolate that melts easily and smoothly. The higher the percentage of cocoa butter in your chocolate, the more likely it is to become discolored.

Blooming Chocolate

• The powdery discoloration on your chocolate's surface is referred to as bloom, and it's simply a portion of the chocolate's cocoa butter rising to the surface. The ideal temperature range for storing chocolate is narrow, approximately 60 to 65 degrees Fahrenheit. At temperatures higher than that -- ordinary room temperature, in other words -- some of the less stable fats in the cocoa butter can melt and find their way to the surface, where they recrystallize and give the chocolate a gray appearance.

Fixing the Problem

• Chocolate that has bloomed heavily can become crumbly, though its flavor and other characteristics are unchanged. If you're going to bake with it, you can simply go ahead and use it as you ordinarily would. When it's heated, the fat that causes blooming simply melts back into the chocolate. If the chocolate is to be used for candy-making, you need to retemper it. That means melting it gently to dissolve its existing structure, cooling it to a specific temperature range -- typically 82 to 84 F for dark chocolate -- ad finally returning it to a slightly higher temperature, where stable crystals can form but unstable crystals can't. The tempered chocolate cools to a glossy sheen and breaks with a pleasantly crisp and brittle snap.