Limonene Chemistry

Limonene is a monocyclic monoterpene (C₁₀H₁₆) with a six-membered carbon ring and an isopropylidene side chain. In cannabis, it occurs primarily as (+)-limonene (the R-enantiomer), though trace amounts of (-)-limonene may appear depending on cultivar and growth conditions. The molecule is volatile at room temperature, contributing to rapid aroma dissipation in dried material. Limonene biosynthesis in cannabis follows the general mevalonate pathway, with limonene synthase catalyzing the cyclization of geranyl pyrophosphate. Its chemical structure makes it relatively stable under moderate storage conditions compared to other volatile terpenes, though light and heat exposure degrade it over time. Detection methods include gas chromatography–mass spectrometry (GC-MS) and liquid chromatography for precise quantification in breeding populations.

Breeders working with limonene-forward cultivars often track this terpene as a chemotype marker, since its presence and concentration are genetically influenced and moderately heritable. High-limonene lines are selected through controlled crosses and progeny testing, making limonene expression a useful phenotypic target in cultivar development programs.