Milk from which almost all the moisture has been removed. Dry (also called powdered) milk is less expensive and easier to store than fresh milk but has a disadvantage in that it never tastes quite like the real thing. It comes in three basic forms — whole milk, nonfat milk and buttermilk. Because of its milk fat content, dry whole milk must be refrigerated. Nonfat dry milk is available in regular and instant forms; the former tastes slightly better, while the latter mixes more easily. Powdered buttermilk is simply desiccated buttermilk and is generally used for baking. Until opened, dry nonfat milk and buttermilk can be kept in a cool, dry place for up to 6 months. Refrigerating opened packages will help retain their freshness. A USDA "U. S. Extra Grade" shield on the label signifies that the product meets exacting government quality standards. Dry milks may or may not be fortified with vitamins A and D.