The fruit you’re thinking of is almost certainly a blood orange, a variety of sweet orange with deep crimson to ruby-red flesh hidden beneath a familiar orange peel. There’s also a second possibility: the Cara Cara navel orange, which has a pink-to-red interior. Both look like standard oranges from the outside, but surprise you with vivid color when you slice them open.
Blood Oranges: The Classic Red-Fleshed Orange
Blood oranges are the most dramatically red citrus you’ll find. The flesh ranges from deep purple to bright crimson with streaks of the typical orange color mixed in, depending on the variety. Three main types dominate grocery stores: Moro (the darkest, sometimes nearly purple), Tarocco (often considered the sweetest), and Sanguinello (known for especially high vitamin C). The flavor has a distinctive berry-like quality that sets it apart from a regular orange. A Jesuit scholar named Ferrari first described the fruit in 1646, writing about an orange with purple flesh that “tasted strangely like a grape.”
From the outside, blood oranges can be tricky to identify. Some develop a reddish blush on the peel, but others look almost identical to a navel or Valencia orange. The Moro variety is most likely to show external redness, while a Tarocco might have a completely orange exterior with deeply pigmented flesh inside. The only reliable way to know is to cut one open or buy them labeled at the store.
Why the Flesh Turns Red
The red color comes from anthocyanins, the same class of pigments that make blueberries blue and red cabbage purple. Blood oranges are the only commonly available citrus fruit that produces these pigments in significant amounts, which is why that interior color is so striking and unexpected.
Cold temperatures are the trigger. While the fruit is still on the tree, exposure to cool nights kicks off anthocyanin production. The flesh starts developing color after relatively modest cold accumulation, but the peel needs roughly twice as much cold exposure before it shows any red, which is why many blood oranges look ordinary on the outside while being vividly red within. Research on the Tarocco variety found that peel pigmentation begins 8 to 15 days after the flesh has already started turning red. This is also why blood oranges grown in warmer climates sometimes have less intense color. Sicily, with its cool Mediterranean winters and the influence of Mount Etna’s altitude, produces some of the most deeply pigmented blood oranges in the world.
The genetic mechanism behind it is fascinating. A piece of mobile DNA called a retrotransposon inserted itself near the gene responsible for anthocyanin production. This insertion made the gene respond to cold, essentially creating an on-switch that activates only when temperatures drop. A blood orange of Chinese origin, called Jingxian, developed the same trait independently through a similar genetic event, suggesting this type of mutation has happened more than once in citrus history.
Cara Cara Oranges: The Pink Alternative
If the fruit you saw had a softer, pinkish-red interior rather than a deep crimson, it was likely a Cara Cara navel orange. Originally discovered in Venezuela, the Cara Cara looks exactly like a Washington navel orange on the outside. Cut one open and the flesh is a striking deep pink, similar to the darkest red grapefruit varieties.
The key difference is the pigment. Cara Caras get their color from lycopene, the same compound that makes tomatoes red, rather than the anthocyanins found in blood oranges. This means the color is more uniformly pink throughout the flesh rather than appearing in dark red streaks and patches. The flavor is sweeter and less tart than a blood orange, without that berry-like undertone. Think of it as a navel orange with a slightly more complex, almost cranberry-tinged sweetness.
Nutritional Differences
Both red-fleshed varieties offer solid vitamin C content, typically in the range of 32 to 42 milligrams per 100 milliliters of juice. That means a single large orange gets you roughly halfway to the daily recommended intake (75 mg for women, 90 mg for men). The real nutritional edge of blood oranges comes from those anthocyanin pigments, which act as antioxidants. Studies comparing pigmented and non-pigmented orange varieties found that the antioxidant power of blood orange juice comes primarily from its total phenol content rather than vitamin C alone. In other words, the red color isn’t just cosmetic.
Cara Caras bring lycopene to the table instead, which has its own well-studied antioxidant properties. Either way, choosing a red-fleshed orange over a standard one gives you an extra category of beneficial plant compounds you wouldn’t otherwise get from citrus.
How to Use Them
The vivid color of both varieties makes them natural standouts in dishes where a regular orange would blend in. Blood oranges work especially well in salads with bitter greens like arugula or radicchio, where their tartness and berry notes complement the bitterness. They’re also excellent juiced into vinaigrettes, added to sparkling water, or used as a garnish for cocktails. The deep red juice makes a visually striking glaze for roasted meats or a base for sorbet.
Cara Caras, being sweeter and less acidic, are better suited to eating fresh or tossing into grain bowls and fruit salads where you want color without sharpness. Their segments hold together well and look beautiful over cottage cheese or yogurt. Both varieties are typically in season from December through April in the Northern Hemisphere, though Cara Caras sometimes appear as early as November.
How to Pick Them at the Store
Blood oranges are usually sold by name, so look for labels mentioning Moro, Tarocco, or simply “blood orange.” If you’re shopping at a farmers’ market and the oranges aren’t labeled, look for a slight reddish blush on the skin, though this isn’t always present. The fruit should feel heavy for its size, which indicates juiciness. Smaller blood oranges tend to be more intensely pigmented than larger ones.
Cara Caras are almost always sold under their own name because there’s no way to distinguish them from a regular navel by appearance alone. The skin is smooth and orange, the shape is round with a characteristic navel at the bottom, and nothing about the exterior hints at the pink flesh inside. If you spot “red navel” on a label, that’s the same fruit.