Expression
Expression as a method of fragrance extraction where raw materials are pressed, squeezed or compressed and the oils are collected. In contemporary times, the only fragrant oils obtained using this method are the peels of fruits in the citrus family. This is due to the large quantity of oil is present in the peels of these fruits as to make this extraction method economically feasible. Citrus peel oils are expressed mechanically, or cold-pressed. Due to the large quantities of oil in citrus peel and the relatively low cost to grow and harvest the raw materials, citrus-fruit oils are cheaper than most other essential oils. Lemon or sweet orange oils that are obtained as by-products of the commercial citrus industry are among the cheapest citrus oils.
Expression was mainly used prior to the discovery of distillation, and this is still the case in cultures such as Egypt. Traditional Egyptian practice involves pressing the plant material, then burying it in unglazed ceramic vessels in the desert for a period of months to drive out water. The water has a smaller molecular size, so it diffuses through the ceramic vessels, while the larger essential oils do not. The lotus oil in Tutankhamen's tomb, which retained its scent after 3000 years sealed in alabaster vessels, was pressed in this manner.
Read more about this topic: Fragrance Extraction
Famous quotes containing the word expression:
“Removed from its more restrictive sense, masturbation has become an expression for everything that has proved, for lack of human contact, to be void of meaning. We have communication problems, suffer from egocentrism and narcissism, are frustrated by information glut and loss of environment; we stagnate despite the rising GNP.”
—Günther Grass (b. 1927)
“All expression of truth does at length take this deep ethical form.”
—Henry David Thoreau (1817–1862)
“The true poem is not that which the public read. There is always a poem not printed on paper,... in the poet’s life. It is what he has become through his work. Not how is the idea expressed in stone, or on canvas or paper, is the question, but how far it has obtained form and expression in the life of the artist. His true work will not stand in any prince’s gallery.”
—Henry David Thoreau (1817–1862)