The flesh should be deep colored with mature seeds. Most watermelons have dark brown or black seeds. The seedless variety produces a few white seeds. Uncut watermelons have a shorter refrigerator life, so store at room temperature until ready to chill and eat. Tightly cover cut pieces in plastic wrap and store in the refrigerator for 2 to 3 days.
Watermelons are low in calories and very nutritious.
Watermelon is high in lycopene, second only to tomatoes. Recent research suggests that lycopene, a powerful antioxidant, is effective in preventing some forms of cancer and cardiovascular disease. According to research conducted at the University of North Carolina at Chapel Hill, men who consumed a lycopene-rich diet were half as likely to suffer a heart attack as those who had little or no lycopene in their diets. Watermelon is also high in Vitamin C and Vitamin A, in the form of disease fighting beta-carotene. Research also suggests that the red pigmented foods provide this protection.