Limonene is a cyclic monoterpene. The (+)-form, d-limonene, dominates citrus peel oil and smells of orange and lemon; cannabis produces mainly the (-)-form, which smells more pine-lemon. It is one of the most frequent dominant terpenes in commercial flower, often paired with beta-caryophyllene in the "sweet, gassy, citrus" profile that dominates many markets.
In practice
Typical flower readings run 0.1-0.8% w/w. Limonene is volatile and oxidises in air; oxidation products are part of the stale smell of old buds. Note that a lemony aroma isn't proof of limonene: some citrus-like notes come from other compounds such as terpinolene, valencene or esters. Only a terpene test tells you.
Don't confuse with
- Valencene: a citrus-smelling sesquiterpene, much less volatile.
- Linalool: floral, not citrus.
- Citral/lemon aldehydes: other citrus compounds, minor in cannabis.
Myth check
Claims that limonene makes a cultivar "uplifting" are not established by controlled human data; effects are only reported. See Mythbusters.
A monoterpene is a ten-carbon terpene made from geranyl pyrophosphate, such as myrcene, limonene, pinene or terpinolene; they are the most volatile terpenes and the first lost in drying.A dominant allele is one whose effect shows in the phenotype even when only one copy is present, masking the other (recessive) allele at that locus.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.Beta-caryophyllene is a spicy, peppery sesquiterpene common in cannabis, notable as a dietary terpene that also binds the CB2 receptor in laboratory studies.Terpinolene is a monoterpene with a fresh, herbal, piney-citrus-floral aroma that dominates a distinctive, less common cannabis chemotype.Valencene is a sweet, citrus, orange-peel sesquiterpene named after Valencia oranges and found as a minor terpene in some cannabis cultivars.A terpene test measures the individual terpenes and total terpene content of a sample, usually by GC-FID or GC-MS, reported in % w/w or mg/g.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.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.
