The blood orange is a variety of orange (Citrus × sinensis) with crimson, almost blood-colored flesh.
The distinctive dark flesh color is due to the presence of anthocyanins, a family of antioxidant pigments common to many flowers and fruit, but uncommon in citrus fruits. Chrysanthemin (cyanidin 3-O-glucoside) is the main compound found in red oranges. The flesh develops its characteristic maroon color when the fruit develops with low temperatures during the night. Sometimes, dark coloring is seen on the exterior of the rind, as well, depending on the variety of blood orange. The skin can be tougher and harder to peel than that of other oranges. Blood oranges have a unique flavor profile compared to other oranges, being distinctly raspberry-like in addition to the usual citrus notes.