A monoterpene contains ten carbons, two isoprene units, and is made from geranyl pyrophosphate by terpene synthase enzymes. Monoterpenes dominate the bright top notes of cannabis aroma: myrcene (musky, earthy), limonene (citrus), alpha- and beta-pinene (pine), terpinolene (fresh, herbal), ocimene (sweet, green) and linalool (floral, a monoterpenoid alcohol).
In practice
Because they are small and volatile, monoterpenes evaporate and oxidise more readily than sesquiterpenes. Ross and ElSohly (1996) reported large monoterpene losses after air-drying, with the sesquiterpene share rising in comparison. That is the chemistry behind the grower rule: dry slowly and cool, cure gently and keep jars cool and dark. Flower that smelled loud on the plant and dull after a fast, warm dry has lost monoterpenes.
Don't confuse with
- Sesquiterpene: C15, heavier and less volatile (beta-caryophyllene, humulene).
- Monoterpenoid: an oxygenated monoterpene such as linalool or eucalyptol; often lumped in.
- Terpene profile: the mix measured in a given sample.
Geranyl pyrophosphate (GPP) is a ten-carbon terpene precursor that cannabis uses both to build monoterpenes and, joined to olivetolic acid, to make the cannabinoid precursor CBGA.Terpenes are volatile hydrocarbon compounds built from five-carbon isoprene units; in cannabis they are made in the trichome heads and are a major part of aroma and flavour.Limonene is a monoterpene with a citrus aroma, found in citrus peel and many cannabis cultivars, where it is often among the top three terpenes.Terpinolene is a monoterpene with a fresh, herbal, piney-citrus-floral aroma that dominates a distinctive, less common cannabis chemotype.Linalool is a floral, lavender-scented monoterpene alcohol found in lavender and some cannabis cultivars, usually at low levels below 0.3% w/w.A sesquiterpene is a fifteen-carbon terpene made from farnesyl pyrophosphate, such as beta-caryophyllene, humulene and bisabolol; they are heavier and less volatile than monoterpenes.Beta-caryophyllene is a spicy, peppery sesquiterpene common in cannabis, notable as a dietary terpene that also binds the CB2 receptor in laboratory studies.A terpene profile is the measured mix of terpenes in a sample, reported as each compound's % w/w and the total, used to describe and compare cultivar aroma chemistry.Myrcene (beta-myrcene) is a monoterpene with a musky, earthy, ripe-fruit aroma and is the most common dominant terpene in commercial cannabis flower.Alpha-pinene is a bicyclic monoterpene with a sharp pine-resin aroma, the main terpene of conifer needles and a common, usually secondary, terpene in cannabis.
