All real chocolate comes from the cacao bean, the fruit of a tropical tree, Theobroma cacao. Chocolate is made from roasted, pulverized cacao beans, which are then combined with sugar, and in some cases vanilla and lecithin. Much of the quality of the chocolate will depend on the origin and quality of the beans. Chocolate is labeled unsweetened, bittersweet, or semisweet depending on the percentage of cacao the chocolate contains. Here's a rundown of the various types of chocolate:
Since most recipes calling for bittersweet or semisweet chocolate were developed using chocolate with a cacao percentage around 35%, substituting some of the super-high percentage chocolates that are increasingly available can cause cakes to be dry or ganaches to curdle. If you want to experiment with using these higher-cacao products, chocolate guru Alice Medrich recommends using 25% to 35% less chocolate than called for in the recipe and adding up to 1-1/2 teaspoons more granulated sugar for each ounce of chocolate originally called for.
Chocolate for baking is manufactured in squares, thin bars, and thick blocks. Thin bars are convenient to store and can be easier to chop than blocks, which take a bit of elbow grease to knock apart (but are better for making decorative shavings and curls).
Some better quality chocolates only come in huge blocks, which are great for pros but may be too big a quantity for home cooks. Luckily, specialty stores often sell smaller chunks of these blocks wrapped in plastic. Lindt, Guittard, Scharffen Berger, Valrhona, and Trader Joe’s are some brands to keep on hand.
If a recipe specifies a cacao percentage, stick to it. If not, don’t choose one higher than 75 percent cacao; otherwise, there may not be enough sugar in the recipe to produce the ideal finished texture.
Store chocolate in a cool, dry place. A warm or humid kitchen can cause the fat or sugar or both to rise to the chocolate’s surface, resulting in a grayish-white coating called bloom. Either way, though the chocolate may not have the same texture eaten straight, it will work just fine in baking.
Chocolate will keep for a year at room temperature, if kept below 70°F. Wrap it in a few layers of plastic wrap to keep it as airtight as possible and put it in a dark cupboard, away from strong-smelling foods. (Chocolate, like butter, will absorb strong aromas.)
You can store chocolate in the refrigerator or freezer, but a moist environment isn't ideal. If you do chill your chocolate, bring it to room temperature while still wrapped to prevent condensation from forming, as any water on the chocolate can interfere with its ability to melt smoothly.
Stored in a cool, dry cupboard, dark bar chocolate will last a year (six months for milk chocolate).