The numerous varieties of cooking ingredients on supermarket shelves can leave even the most seasoned chef wondering what to choose. Let Martha clear up the culinary confusion.

Both types of cocoa powder come from cocoa beans that have been fermented, dried, roasted, pressed, and ground. In the Dutch process, the beans are also treated to make them less acidic, resulting in a darker powder. Although some favor the flavor of the regular version, our editors find that Dutch-process cocoa powder has a smoother, more chocolaty taste and disperses more readily in liquids, making it easier to stir into batters and hot chocolate. But, because Dutch-process powder is neutral to slightly alkaline, the reasoning goes, it may not react with baking soda properly and could inhibit rising. Bottom line: With baking, it's always safest to follow a recipe to the letter. If however, you don't have one type of cocoa available, try swapping in the other.

Most flours start out as kernels of wheat, but the finished products vary greatly. The one you use will affect the structure, texture, flavor, and appearance of your baked goods.

All-purpose flour is the most common; as its name suggests, it is appropriate for cakes, cookies, pie-crusts, and more. Cake flour has less protein than all-purpose flour, so it produces exceptionally soft, velvety cakes. At the other end of the spectrum is bread flour, which contains the most protein and results in lofty, chewy loaves. All-purpose, cake, and bread flours are refined, meaning the wheat germ and bran have been removed. Whole-wheat flour, on the other hand, contains every part of the wheat kernel. To make your favorite baked goods more healthful, substitute whole-wheat flour for a portion of the all-purpose flour; it lends a rich, nutty flavor and provides a healthy dose of fiber and nutrients. Start with one part whole wheat to two parts all-purpose, and experiment until you find the right balance of taste and texture.

As with cheese, sheep and goat yogurts have a tangy quality, but the best ones have subtle flavor differences, without a strong "sheep" or "goat" taste. In terms of nutrition, sheep's milk contains more calcium, twice as much fat, and 40 percent more protein than goat's or cow's milk. Because sheep's milk has a higher solid content, no thickeners are needed to make a full-bodied, slightly grainy yogurt. Thinner cow and goat yogurts usually rely on additives, such as nonfat dry milk. Sheep and goat products are not good options for lactose-intolerant people (both have about as much lactose as cow products do), but they are worth a try for people with cow's milk allergies and those looking for something new.

Vanilla is available in many forms, but the most common is liquid extract. Naturally derived extract is amber in color with a robust, nuanced taste, a rich composite of more than 200 flavor compounds in vanilla. Imitation extract contains only chemically synthesized vanillin, the primary flavor compound, and as a result lacks complexity and has a bitter aftertaste. Vanilla is used in small quantities and has a long shelf life, so it is worth buying the real thing: Look for bottles labeled "pure vanilla extract." Although extract is suitable in most dishes, vanilla beans lend a purer taste. Use beans in foods where vanilla is the defining flavor, such as custard and ice cream.

Extra-virgin olive oil, made from the first pressing of olives after harvest, has a bright, fruity taste. Neither heat nor chemicals are used to extract the oil, so it is at its freshest and most healthful. Virgin olive oil is also extracted without heat or chemicals but is more acidic than extra-virgin and may not be from the first pressing. Bottles labeled "olive oil" or "pure olive oil" typically contain blends from second or third pressings, with virgin or extra-virgin oil added for flavor. Ideally, you should keep two kinds of extra-virgin olive oil on hand: an inexpensive one for cooking and a premium one for dishes like vinaigrettes that will showcase its nuanced flavor and aroma. To prevent the oils from turning rancid, store in a cool, dark place; they will keep for about a year.

A relatively new addition to the roster of vinegars, white balsamic vinegar has a golden hue and tastes notably milder than the original. Traditional balsamic vinegar comes from the Modena region of Italy, where it is made from grapes. A concentrated grape juice is cooked in open vats and then aged in a series of wooden barrels for five to more than 50 years, resulting in a deep brown and exceptionally sweet and syrupy vinegar. White balsamic vinegar is cooked under pressure to prevent caramelization and aged for just a year. The result is much lighter in color, with a less sweet flavor that is ideal for sauces, dressings, dishes that traditional balsamic vinegar would discolor, and any recipe that calls for a more mild vinegar.