There are two types of cocoa: natural (nonalkalinized) and Dutch Process (alkalinized). Natural cocoa powder (also called unsweetened) is simply untreated cocoa powder; it is rarely labeled with the word natural on the package, but will simply say cocoa. Dutch Process cocoa ― so named because a Dutch man invented the process –– has been treated with an alkali to reduce its harshness and acidity. Along the way, "dutching" gives the cocoa a rich dark appetizing color, mellow toasted flavor, and coffee notes.
If a recipe simply calls for cocoa, use natural cocoa. Because Dutch Process cocoa is more alkaline, it may alter the chemistry in a recipe, reacting differently than natural cocoa with baking soda or baking powder. In recipes with no leaveners, natural and Dutch-process cocoa are interchangeable.
It's best to store cocoa away from herbs and spices and other aromatic substances, as it picks up other flavors relatively easily.
After fermentation, the seeds are dried in the sun before they are bagged and shipped to chocolate factories. At the factory, the cocoa beans are cleaned, roasted, and winnowed to remove their hulls. Winnowing also breaks the hulled beans into pieces, called cocoa nibs. Nibs from different varieties and origins are usually blended after roasting, to create different chocolates with distinct flavor characteristics, just as grapes are blended in making wine. After blending, the nibs are ground into chocolate liquor, which you know as unsweetened baking chocolate.
Bloomed chocolate is also safe to eat as is, but its texture may be grainy, and it may be less flavorful. If you have a choice, melt and use bloomed chocolate in a recipe. Otherwise (and most chocolate lovers would agree), bloomed chocolate is surely better than no chocolate at all for other purposes.
Because chocolate absorbs flavors and odors, wrap in aluminum foil and again in plastic and store it in a dry, cool place.
Milk and white chocolates lose freshness more quickly, so if you purchase more than you will use in two months, keep the extra frozen. Wrap with aluminum and plastic, and store in a zip-top bag.
Before using frozen chocolate, thaw completely in the refrigerator without removing it from the bag. This will prevent condensation, which will damage the chocolate.
Keeping chocolate on-hand means you can make our Cocoa Fudge Cookies whenever the occasion (or craving) calls for them.