This study examined the actual chemical diversity of cannabinoids and terpenes in cannabis flower and the commercial labels used to classify and describe them. The primary focus was on "strain" (cultivar) names and Indica / Sativa / Hybrid labels actually on the products. It was peer reviewed and published in May 2022 in PLOS ONE.
The dataset used was composed of 89,923 flower samples submitted by thousands of different cultivators across six US states. Overwhelmingly (96% of samples), THC levels were much higher compared to levels of all other cannabinoids, so this is primarily comparing THC-dominant chemotypes.
The terpenes myrcene, caryophyllene, and limonene were most dominant on average. The total terpene content averaged 2%, and the individual terpenes rarely exceeded 0.5%.
Terpene content "displayed a modest but robust positive correlation with total cannabinoid content (rs = 0.37, P < 0.0001), suggesting that the production of one type of compound doesn’t come at the expense of the other."
This is interesting as some believe that maximizing THC comes at the expense of terpenes. These results seem to show that is not the case: high terpene content was associated with high cannabinoid content.
The results for the correlation of specific terpene profiles and the labels Indica / Sativa / Hybrid was disappointing - these labels did not reflect consistent terpene profiles or tendencies:
"it is likely that a sample with the label 'Indica' will have an indistinguishable terpene composition as samples labelled 'Sativa' or 'Hybrid.'"
However, the authors did find distinct terpene group clustering and were able to identify 3 main groups based on the two most dominant terpenes. The 3 groups:
- High Caryophyllene and Limonene
- High Myrcene and Pinene
- High Terpinolene and Myrcene
They also observed that the High Terpinolene and Myrcene group had higher CBG content than the other two groups (0.98% vs. 0.65%).
Their analysis of the consistency of terpene profiles with cultivar, or strain names was low in most cases, meaning that strain names do not always reflect a consistent terpene profile.
The authors concluded that using the top two dominant terpenes to categorize products would lead to more reliable product information for patients and consumers.
The full-text article is here at PLOS One.