Sour orange

Also known as bitter oranges. Although well known throughout the Western world, especially in the Mediterranean region, sour oranges are not usually available in the produce market partly due to their much more pungent flavor compared to the sweet varieties. Although all citrus is rich in pectin (the pith of oranges is a major source for commercially produced pectin), the sour orange stands out here—hence its popularity for use in marmalades, not only for the tangy flavor but also because it is possible to make a fine, firm marmalade without the addition of pectin.