The key to keeping basil fresh and fragrant for days (and even weeks) is to NOT store it in the refrigerator. Basil leaves quickly turn black and slimy and lose their signature spicy sweet flavor when refrigerated. A better way to store them is in a jar of water on your kitchen counter top. Pinch the leaves from the stems, spread them on cookie sheets and freeze them. Transfer the frozen leaves to plastic containers and put them back into the freezer for use throughout the winter. Since basil has a high water content it cannot be dried like many other herbs, as it will turn black and lose its flavor. It will also turn black if chopped or bruised and exposed to air.
Basil is a good source of Protein, Vitamin E (Alpha Tocopherol), Riboflavin and Niacin, and a very good source of Dietary Fiber, Vitamin A, Vitamin C, Vitamin K, Vitamin B6, Folate, Calcium, Iron, Magnesium, Phosphorus, Potassium, Zinc, Copper and Manganese.
Information from Siskiyou Cooperative