On Food and Cooking

Citrus Peel The intensely flavored citrus peel
has long been used to flavor dishes (for
example, dried orange peel in Sichuan
cooking), and as a preparation in itself in the
form of candied rind. The outer epidermis
contains the aromatic oil glands, while the
underlying white, spongy, pectinrich albedo
usually contains protective bitter phenolic
substances. Both the oil with its terpenes and
the antioxidant phenolics are valuable
phytochemicals (pp. 256, 257). The bitters are
water-soluble, while the oils are not. Cooks
can therefore leach the peel repeatedly with
hot (rapid) or cold (slow) water to remove the
bitter compounds, then gently cook the peel if
still necessary to soften the albedo, and finally
infuse it with a concentrated sugar syrup.
Through all this processing the water-
insoluble oils stay largely in the rind.
Marmalade, a sugar preserve that includes
citrus peel, was originally a Portuguese fruit
paste made with quince, but by the 18th