Blood oranges are a very unique-looking fruit. When you cut into an orange, you expect it to be, well, orange. Blood oranges are red inside, and can range from having a handful of red streaks inside to being so dark that they appear to be purple.
Blood oranges have been cultivated for centuries, primarily in Sicily, Italy, and are grown in many Mediterranean countries. The oranges were introduced to the US in the 1930s and are grown in much of the Southwestern US, from California to Texas. The season lasts from November to May, with the peak coming between December and March. There are a few varieties of blood orange. Moro are the darkest blood oranges, and have the sweetest flavor, with berry tones. Sanginello is of medium sweetness with a medium amount of color, and is from Spain. Tarocco is the most popular variety on Italy and is considered to be the sweetest of the blood oranges. Type aside, as a general rule all blood oranges are quite sweet – sweeter than many regular varieties of orange – and have floral notes to them.
If you see a recipe that calls for blood oranges, you can easily substitute regular (non-blood) oranges or orange juice in that recipe. You might end up missing out on some of the lovely pink color that blood oranges can infuse, but the recipe will work just fine.