Grapes should be refrigerated to extend their shelf life. They should not be washed until they are ready for use due to the fact that excess moisture may cause them to spoil.
Grapes continue to ripen after they have been harvested. Refrigerating them slows the ripening process down. Fresh grapes have a green stem, while older grapes have dried out and brown stems. Grapes can also be frozen to extend their shelf life.
One cup of grapes has 104 calories. They contain high levels of vitamin C and vitamin K. They are low in saturated fat, sodium and cholesterol. Grapes are primarily composed of carbohydrates and have high levels of sugar.