Now we enter our LAST chapter of EO molecules. These HEAVY Notes have deep, rich aroma that lasts and lasts and lingers and lingers. I love the HEAVY Notes. They are the SESquiTerpenes.
Most essential oils possess some HEAVY Note Sesquiterpene molecules. Some essential oils are composed almost entirely of Sesquiterpenes (pronouced: SESS-kwi-TUR-peen). These HEAVY Note molecules tend to have a “woody, earthy, intense” aroma.
Some oils that possess high Sesquiterpene molecules come from distilling trees and roots. Hong Kuai, Cedarwood, Blue Cypress, and Sandalwood are the most prominent “wood” oils with very high Sesquiterpene and Oxygenated Sesquiterpene content. The “root” oils include Valerian, Vetiver, and Ginger.
The HEAVY Note Sesquiterpene molecules are the largest so far – containing 15 Carbon atoms. They tend to stay in the liquid. These HEAVY molecules don’t “venture out” into the gas phase of the air. If you want to smell them you’ve got to get your nose close to the thin film of oil that’s applied to your skin or to the opening of the bottle. The good NEWS = these HEAVY Sesquiterpenes hang around for a long time (linger-linger-linger-linger).
A strange thing about Sesquiterpenes, they tend to have similar aromas. Remember the rule for Monoterpenes: Shape and Structure of the molecule determines its AROMA. Not true for Sesquiterpenes!!!!!! Likely because they are so large.
Treasure the essential oils for their “lasting” Sesquiterpene aroma. Yesterday we EXPeRiMENTed with the “lasting” aroma of Peppermint. Those who performed the Peppermint EXPeRiMENT would have noted the “sweet” lingering aroma of Peppermint after 90 minutes. You’ve got to love the “lasting” Sesquiterpenes.
Source: Dr. Cole Woolley