This oil, which is not strictly an essential oil according to our definitions, is produced by cold expression of the peel of the fruits from a Citrus species which presumably evolved from the West Indian “shaddock” fruit. Although not a hybrid, the grapefruit did not exist 400 years ago, and it was still a rarity around the beginning of the twentieth century.
Arctander, Steffen . Perfume and Flavor Materials of Natural Origin (p. 330).