Are Blood Oranges Naturally Red?

The first time you peel a blood orange can be a little shocking. That's because on the outside, a blood orange can look almost exactly like a regular orange. But unlike a common, sweet orange or a navel orange or even a tangerine or a clementine, the flesh of a blood orange is, as the name suggests, blood red. So why are blood oranges red while most other varieties of oranges are orange on the inside? And what, exactly, is the difference between blood oranges and oranges? It turns out that there are a lot of differences between blood oranges and regular oranges that extend far beyond the fruit's color.

That's because blood oranges are not regular oranges that have been artificially dyed, as some people might assume upon first encountering the deeply colored fruit. In fact, blood oranges are naturally red. As Harold McGee explains in his book On Food and Cooking: The Science and Lore of the Kitchen, "Blood oranges owe the deep maroon color of their juice to anthocyanin pigments, which develop only when night temperatures are low, in the Mediterranean autumn and winter."

And what's anthocyanin? It's a class of "universal plant colorants responsible for the red, purple, and blue hues evident in many fruits, vegetables, cereal grains, and flowers," write researchers Izabela Konczak and Wei Zhang in the Journal of Biomedicine and Biotechnology. In addition to making the inside of a blood orange look like a ruby, anthocyanin also gives raspberries and blackberries and even darker red tomatoes their purple and blue tones.

But anthocyanin does more than affect the color of fruits. Anthocyanin adds to the nutritional value of the fruit since is a type of flavonoid, also known as an antioxidant. There's some compelling scientific evidence that consuming these antioxidants in fruit like blood oranges can help prevent damage on a cellular level. And regular oranges just don't have the same high levels of antioxidants as blood oranges—so if you're looking to get your flavonoid on, you're better off reaching for a jewel-toned blood orange instead.

Blood oranges also have a slightly different taste than navel oranges or even common oranges that you'd squeeze into juice. While a sweet orange is mainly sweet, the taste of a blood orange is a bit more complex, and as McGee writes, it "combines citrus notes with a distinct raspberry-like aroma."

But when it comes to eating blood oranges, it's like eating any other orange. You can slice it in half, cut it into wedges, or just peel the skin off with your hand and eat the sections straight up. Don't let the name—or the color—freak you out.