Terpenes

Terpenes are small molecules built from isoprene units that plants make for scent, defense and pollinator signaling. Cannabis produces more than 100 of them, and the same compounds appear in citrus peel, pine, hops, black pepper and lavender (Russo 2011). NIH counts about 540 chemical substances in the plant overall, and terpenes are a large share of what is not a cannabinoid (NCCIH).

Monoterpenes such as myrcene, limonene and pinene are the most volatile and evaporate quickly during drying, curing and heated extraction (Bioengineering 2022). Sesquiterpenes such as beta-caryophyllene are heavier and survive processing better. That is why dried flower smells different from fresh, and why distillate has little aroma until terpenes are added back.

Russo's 2011 review proposed that terpenes modify how cannabinoids act, the basis of the entourage hypothesis. He noted that beta-caryophyllene binds the CB2 receptor directly, which makes it technically a dietary cannabinoid (Russo 2011). Most other terpene effects in that review come from animal or in vitro work, and human evidence is thin.

Labs can run a terpene panel that lists each compound by percentage. It is optional on most certificates of analysis.