Blackberries are rich in proanthocyanidins, antioxidants that can help prevent cancer and heart disease. Also rich in Vitamin A, Vitamin C, calcium, folate, magnesium and iron. Available year-round but best locally from May to August. Storage Tips: Store covered containers of berries in a cool, moist area of the refrigerator, such as in the hydrator (vegetable keeper), to help extend the usable life of the fruit. Blackberries can be stored a coupon of days in the refrigerator. Rinse before use.