It is used as a butter substitute, stick margarine is made from vegetable oil that has been hydrogenated to transform it from a liquid oil into a solid fat. When choosing, read the margarine labels carefully so that you know just what you're buying. Regular margarine are 80 percent fat and 20 percent water, flavoring, coloring, and other additives. Butter-margarine blends offer more butter flavor and are usually 40 percent butter and 60 percent margarine. Reduced and low-fat margarines are mostly water and cannot be used for baking.

To store, you can refrigerate margarine for up to 2 months and freeze for no more than 6 months. If you need to reduce fat intake, buy tub margarine instead of stick margarine. Tub margarine contains less than half the amount of trans fatty acids (a harmful type of fat) that stick margarine does. And some tub margarine have no trans fatty acids. Generally, tub-style margarines are not suitable for baking because of their high water content.