Choose Blood Oranges that are firm and heavy for their size. Blood Oranges may have a full-colored blush or have no blush at all. Slice open a blood orange and you'll see a beautiful bright red to deep maroon interior. The intense orange interior has a flavor that hints of fresh raspberry. All oranges contain carotene — that's what makes them orange. Blood Oranges get their red color from high concentrations of a pigment called anthocyanin, a powerful antioxidant that neutralizes the effects of free radicals. Free radicals are the agents believed to be responsible for cancer, aging and other health ailments.