Raisins are simply dried grapes. They are one of the oldest processed foods. Bunches of grapes are hand-picked, dried, graded, cleaned and packed. They are dried either naturally by the sun or by artificial heat. Like other dried fruit, raisins have a chewy texture and very sweet flavor due to their high natural concentration of sugar. California is the largest producer of raisins, accounting for about half the world's supply. The most common type of grape used to make raisins is the Thompson seedless. Zante, Muscat and Sultana grapes are also used.

• Dark seedless raisins are generally made from Thompson seedless grapes. They are sun-dried in the vineyard for several weeks until they are shriveled and dark in color. Their sweet flavor makes them ideal for snacking and for cooking and baking.
• Golden seedless raisins are also made from Thompson seedless grapes, but they are processed differently. The grapes are treated with sulfur dioxide, which prevents the raisins from darkening, and dried with artificial heat resulting in a moist, plump amber-colored raisin. They have a tangy flavor that some prefer for snacking. They are also used for cooking and baking.
• Muscat raisins are made from Muscat grapes. They are large sun-dried raisins that are dark in color. They are very sweet with a fruity flavor. Muscat raisins are good for cooking and baking.
• Sultanas are small dark raisins made from Sultana grapes. They are sun-dried and used primarily for commercial purposes.
• Currants are made from Zante grapes. They are tiny dried fruit that resemble raisins. (See Currant entry for additional information.)

Dark seedless and golden raisins are readily available in supermarkets. Bulk food stores are more likely to carry several varieties of raisins.

When buying in bulk, look for moist-looking raisins.

1 pound seedless raisins = 2-3/4 cups.

After opening, wrap raisins securely in plastic wrap or store in an airtight container at room temperature. They will keep for several months. If refrigerated in a tightly covered container, raisins will keep for up to one year.

Raisins are sometimes soaked in a liquid to plump them (make them soft and moist) before cooking and baking. This may be necessary if raisins are dry and hard. Water is generally used, but fruit juice, brandy or other liquids can be used to add flavor. To plump raisins in water for recipe use, cover them with very warm water and soak for 3 to 5 minutes. Or, place raisins in a small saucepan, cover with water and bring to a boil. Remove the saucepan from the heat and let the raisins stand for 5 minutes. Drain off the liquid and use the raisins as directed in the recipe. To plump and flavor raisins in other liquids, soak them at room temperature for several hours or overnight. Drain them before using.

To prevent raisins from sinking to the bottom of a cake or muffin batter, toss them with a little of the flour used in the recipe. If the raisins are clumped together, separate them with your fingers, making sure all raisins are coated with flour.