What Happens to Terpenes When Hash is Made? Examining the science behind terpenes

 

Hash, also known as hashish, is a concentrated form of cannabis made by separating trichomes from the plant material. Trichomes are tiny, resinous glands that contain cannabinoids, terpenes, and flavonoids. Hash is often made by hand-rolling or pressing the trichomes together, creating a dense block of concentrated resin.

Hash has been used for centuries for its potent effects. While much is known about the active compounds in cannabis, such as THC and CBD, there is still limited research on how terpenes, the aromatic compounds responsible for the plant's distinct smell and taste, change during the hash-making process.

Recent studies have shed some light on the chemical transformations that take place when hash is made and allowed to cure. One such study, conducted by Marchini et al, found that the common cannabis terpene myrcene transforms into a unique monoterpene not found in the resins when they are on the living plant. This terpene has been dubbed "hashishene."

The late hash guru Frenchy Cannoli also organized a collaborative effort called the Trichome Research Initiative that examined the chemical transformation of pressed hash over the course of six months. The findings revealed that monoterpene terpenes, such as myrcene, pinene, or limonene, show more signs of loss or degradation than alcohol terpenoids.

Interestingly, none of the terpenoids measured increased significantly in concentration over time, suggesting that if these terpenoids are transforming rather than evaporating away, they are transforming into compounds that most cannabis testing labs are not measuring.

Myrcene and other terpenes transform due to several main factors - air, light, heat, and pressure - all over time. These transformations likely play a role in the unique effects that hash has compared to cured cannabis flower.

However, the limited research on hashishene and other terpene transformations in hash means that there is still much to learn about this process. More research is needed to fully understand why hash hits differently than cannabis flower and to unlock the potential benefits of these chemical transformations for medicinal and recreational use.

1. Marchini M, Charvoz C, Dujourdy L, Baldovini N, Filippi JJ. Multidimensional analysis of cannabis volatile constituents: identification of 5,5-dimethyl-1-vinylbicyclo[2.1.1]hexane as a volatile marker of hashish, the resin of Cannabis sativa L. J Chromatogr A. 2014 Nov 28;1370:200-15. https://doi.org/10.1016/j.chroma.2014.10.045
2. Dieckmann, R. H., & Palamand, S. R. (1974). Autoxidation of some constituents of hops. I. Monoterpene hydrocarbon, myrcene. Journal of Agricultural and Food Chemistry, 22(3), 498–503. doi:10.1021/jf60193a033
3. Cudlik MC and Buchbauer G. 2020. Influence of Light on Essential Oil Constituents. Handbook of Essential Oils. 3rd Edition. CRC Press. Pg. 28
4. Marchini M, Charvoz C, Dujourdy L, Baldovini N, Filippi JJ. Multidimensional analysis of cannabis volatile constituents: identification of 5,5-dimethyl-1-vinylbicyclo[2.1.1]hexane as a volatile marker of hashish, the resin of Cannabis sativa L. J Chromatogr A. 2014 Nov 28;1370:200-15. https://doi.org/10.1016/j.chroma.2014.10.045