Written by: Dr. Aldwin Anterola, PhD Plant Physiology, Co-Founder & CSO of Veda Scientific
What makes your favorite cannabis strain so special? One hint, it’s not THC! THC is in every strain—and high percentage THC harvests aren’t particularly special. That’s why it is very appropriate that this year’s Emerald Cup, NaPro Research and SC Labs have given the cannabis industry a great and desperately needed push: to stop the madness of buying cannabis based on THC content and start focusing on the components of cannabis that give it its aroma, taste, unique feeling and overall effect. Just like beer and wine, cannabis has natural categories, and we are finally discovering how to define and use these to bring the consumer experience—both recreationally and medicinally—to a new level of quality.
One thing we want to make clear from the outset is that while the terpenes typically analyzed by cannabis testing labs are extremely helpful in understanding the different effects of cannabis, we’ve discovered a lot more information about cannabis by taking analytical testing technology to the next level. We’ve already found examples where this additional information can explain differences between products that look similar on paper based on the “standard” terpenes reported on COAs. The potential for this new information to improve the experiences of both recreational and medical consumers could be dramatic.
Terpenes have been our go-to explanation for the different effects and flavors of cannabis. However, there are other volatile compounds in cannabis that play a major role in determining its aroma and effects on the consumer. So, don’t be surprised if your favorite strain has the same terpene profile as another strain that you know for sure is very different. Other components are at play here. To fully characterize how unique your strain really is, you will need more advanced testing that goes beyond the standard terpenes.
A consumer experience-based classification scheme (Floral, Fruity, Fuel, and Earth) had been proposed for use at the 2021 Emerald Cup and an updated version was proposed again for the 2022 competition. NaPro Research’s PhytoFacts system was used to aid in the classification of strains into six categories (Jacks+Haze, Tropical+Floral, OGs+Gas, Sweets+Dreams, Dessert, and Exotics). These terpene classes align with the flavor profiles being put forth by Terpene Belt Farms, an essential oil producer making investments into advanced research using our two dimensional gas chromatography. This is a very exciting and forward-looking move which recognizes the role of terpenes in imparting organoleptic and medicinal properties to cannabis. These efforts bring new knowledge to consumers who are now empowered to make intelligent choices based on not only THC and/or CBD content, but also other components as well. Slowly but surely, consumers are beginning to realize that there is more to cannabis than THC and CBD, and that the effects they experience with cannabis consumption are not necessarily correlated with cannabinoid content. However, terpenes can explain some of these effects, but not all.
Terpenes can help with assigning different categories of cannabis, but terpenes are not enough. Fortunately at Veda Scientific, we are finally discovering all these components that define consumer-centric categories so we can bring the cannabis experience – both recreationally and medicinally – to a new level of consistency and quality.
Discerning consumers distinguish different strains of cannabis from one another, and oftentimes would have certain preferences over other strains. Cannabis consumers are also affected differently by different strains (and sometimes similarly by similar strains), so it is important that strain designations are consistent across the industry, and a reliable classification scheme be established to help consumers choose the products that work best for them. Terpenes are very useful in defining these categories, although the limited number of standard terpenes currently being tested by most labs do not capture the full complexity of high-quality cannabis strains and hinders consistent classification.
Looking Beyond Terpenes and Cannabinoids
Besides terpenes and cannabinoids, there are other volatile compounds in cannabis that are not as abundant but are nevertheless so potent that they can change how a strain is perceived and experienced by the consumer. These other volatile compounds are not included in a standard terpene test, which is usually done by gas chromatography with a flame ionization detector (GC-FID) or gas chromatography with a mass spectrometer (GC-MS). In fact, it would be very difficult to detect these minor volatile compounds (including other terpenes) using GC-FID and GC-MS due to the abundance of terpenes in cannabis and the inherent limitations of using one-dimensional gas chromatography (i.e. GC-FID and GC-MS) for cannabis.
In order to understand the full complexity of cannabis, Veda Scientific has been using two-dimensional gas chromatography-mass spectrometry (2D-GC-MS a.k.a. GCxGC-MS) to analyze all the volatile compounds (including terpenes) in a variety of cannabis strains and essential oils. Besides detecting a variety of other volatile compounds, we also found that up to more than half of the terpene content in cannabis are not accounted for when relying solely on the standard terpenes that traditional (one-dimensional) gas chromatography measures in a terpene test (see Tables 1 and 2, as discussed below). These results suggest that there are more terpenes in cannabis that we are not regularly measuring, and we can expand the list of volatile compounds that can be tested to better explain how one strain differs from another and what characterizes certain categories that have similar effects on the consumer.
Table 1. Percentage of Different Categories of Volatile Compounds in Cannabis Flowers
There are more terpenes in cannabis besides the “standards” that are typically analyzed by GC-FID and GC-MS, as shown in Table 1. For example, some strains like OVD, GBD and NW with 24-35% of the volatile compounds consisting of standard terpenes, have 20-25% nonstandard terpenes. In the case of AG, only 17% of the volatile compounds are standard terpenes while almost 40% are nonstandard terpenes. So even though the standards can account for most of the terpenes in some strains such as PFBD and ZBD (where the standard terpenes comprise 40-50% of the volatile compounds and only 6-11% are nonstandard terpenes), more than half of the terpenes are not accounted for by the standard terpene test in most of the strains.
Other volatile compounds, such as alcohols, aldehydes, ketones, esters, phenolics and thiols, also contribute to the aroma of certain strains. Thiols, in particular, are responsible for the skunk-like smell, while esters are known to have fruity scents, among other flavors (e.g. rum and honey). The other classes of compounds, such as aldehydes and ketones have been used in the perfume and flavor industry, so they can never be ignored when present in uniquely smelling strains because these potent odorants can undoubtedly influence the aroma and overall effects of cannabis on the consumer. Table 1 shows that these other volatile compounds besides terpenes can be detected in cannabis by GCxGC-MS. More volatile compounds can be detected by GCxGC-MS in enriched preparations, such as cannabis essential oils (Table 2).
Table 2. Percentage of Different Categories of Volatile Compounds in Cannabis Essential Oils
Minor volatile components present at very low (almost undetectable) levels can exert a very powerful influence on the aroma of cannabis. A case in point is the presence of thiols which can only be 0.0003-0.004% of the essential oil (Table 2) yet imparts the unmistakable skunky smell. Different combinations of minor components in cannabis will also influence its overall aroma, just like small amounts of spices can influence the overall taste of a dish. It would not be surprising to see two organoleptically different strains have the same standard terpene profiles, because their chemical differences would have been in the volatile compounds present at lower levels than the more abundant terpenes. It is therefore important to expand the analysis of volatile compounds beyond the standard terpenes, so these data can also be used as additional criteria when assigning cannabis strains into their respective categories.
Testing for the purpose of classification does not have to be based on a limited number of terpenes, nor does it have to be based on known compounds only. The use of GCxGC-MS which enables untargeted analysis of all volatile compounds and the use of all these data to compare strains with one another can be the next step to cannabis classification. This is what Veda Scientific does when testing cannabis for terpenes and other volatile compounds. The data generated with GCxGC-MS can tell us more about the product and what makes it different or similar to other strains. This type of data can be used not only for classification, but also for authentication, formulation, marker identification, quality control, strain selection, product differentiation, labeling, intellectual property claims, and simply understanding more about the known and potential benefits of cannabis, so consumers (and producers) are well informed and empowered to choose what is best for them.