Grape juice is made from natural juices extracted from crushed grapes. Sometimes these juices are condensed and mixed with water later to produce juice. Many commercial grape juice products also contain sugar or other sweeteners, preservatives, and artificial colors or flavors
Grape juice that is marketed as 100 percent juice contains only the juice squeezed directly from the fruit or juice that is condensed and later reconstituted with water. The U.S. Food and Drug Administration regulates this to ensure that companies are making honest claims about their products.
Most purple grape juice is made from concord grapes, which contain antioxidants. Antioxidants have been shown in many studies to provide health benefits, such as a reduction in heart disease and cancer. While these antioxidants, such as flavonoids, do not generally appear in the list of ingredients on the bottle of juice, they occur naturally in the juice itself. White grape juice often contains a preservative, potassium metabisulfite, that helps maintain the color and prevent the juice from turning brown.
Grape juice that is labeled as a "grape drink" or "grape cocktail" contains other ingredients, such as added sweeteners or artificial flavors or colors. The sweeteners may be sugar, or they may be an artificial product, such as aspartame or sucralose. Artificial flavors are sometimes used to enhance the way the juice tastes, while artificial colors are used to influence the way the juice looks.