Valencia oranges, also referred to as juice oranges, yield more juice than navel oranges, but navel oranges are a better choice for zest because of their thick, rough skin. The bitter Seville oranges have the most acidity and intensity of all oranges. They are ideal for making orange curd, but the peel, which has a horrible taste unless it is heavily sugared as for marmalade, should be discarded. These oranges are very thick skinned but also very juicy. Their juice freezes well. They are available from January through March.