On food and cooking the science and lore of the kitchen ( PDFDrive ) 722

CitrusPeelTheintenselyflavoredcitruspeel
has long been used to flavor dishes (for
example, dried orange peel in Sichuan
cooking),andasapreparationinitselfinthe
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.Boththeoilwithitsterpenesand
the antioxidant phenolics are valuable
phytochemicals(pp.256,257).Thebittersare
water-soluble, while the oils are not. Cooks
can therefore leach the peel repeatedly with
hot(rapid)orcold(slow)watertoremovethe
bittercompounds,thengentlycookthepeelif
stillnecessarytosoftenthealbedo,andfinally
infuse it with a concentrated sugar syrup.
Through all this processing the waterinsoluble 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


century the high-pectin, readily gelled sour
orange had begun to replace the quince.
Marmalade made with sweet oranges doesn’t
gel as readily and lacks the characteristic
flavor, including a bitterness that helps
balancethesugar.
Asistrueformostfruits,theskinofcitrus
fruitsismoreeasilyremovedfromthe

underlyingtissuebybrieflyimmersingthe
fruitinsimmeringwater.Thickcitrusrinds
requireanimmersionofseveralminutes.Heat
softensthecell-wallcementthatattachesrind
tofruit,andmayalsoencouragesome
enzymestobegintodissolvethecement.
Kinds of Citrus Fruits Trees in the genus
Citrus are wonderfully variable and prone to
formhybridswitheachother,whichmakesit
a challenge for scientists to work out family
relationships. Currently it’s thought that the
common domesticated citrus fruits all derive
from just three parents: the citronCitrus