Minor, Nonterpenoid Volatile Compounds Drive the Aroma Differences of Exotic Cannabis

Abstract

Cannabis sativa L. produces a wide variety of volatile secondary metabolites that contribute to its unique aroma. The major volatile constituents include monoterpenes, sesquiterpenes, and their oxygenated derivates. In particular, the compounds ß-myrcene, D-(+)-limonene, ß-caryophyllene, and terpinolene are often found in greatest amounts, which has led to their use in chemotaxonomic classification schemes and legal Cannabis sativa L. product labeling. While these compounds contribute to the characteristic aroma of Cannabis sativa L. and may help differentiate varieties on a broad level, their importance in producing specific aromas is not well understood. Here, we show that across Cannabis sativa L. varieties with divergent aromas, terpene expression remains remarkably similar, indicating their benign contribution to these unique, specific scents. Instead, we found that many minor, nonterpenoid compounds correlate strongly with nonprototypical sweet or savory aromas produced by Cannabis sativa L. Coupling sensory studies to our chemical analysis, we derive correlations between groups of compounds, or in some cases, individual compounds, that produce many of these diverse scents. In particular, we identified a new class of volatile sulfur compounds (VSCs) containing the 3-mercaptohexyl functional group responsible for the distinct citrus aromas in certain varieties and skatole (3-methylindole) as the key source of the chemical aroma in others. Our results provide not only a rich understanding of the chemistry of Cannabis sativa L. but also highlight how the importance of terpenes in the context of the aroma of Cannabis sativa L. has been overemphasized.

Nonterpenoid Chemical Diversity of Cannabis Phenotypes Predicts Differentiated Aroma Characteristics

“…In fact, the majority of phenohunting aimed at developing new aromas and flavors relies heavily on sensory analysis of the offspring. , Nonetheless, utilizing chemical analysis for the offspring is becoming more common. , However, these analyses, which are typically conducted at regulated analytical cannabis testing laboratories, usually only test for certain dominant terpenes such as d -limonene, β-myrcene, β-caryophyllene, humulene, or terpinolene, among others . As demonstrated in our previous study, terpenes often have minimal influence on the unique aroma of cannabis products . Instead, minor nonterpenoid compounds often drive aroma differences; therefore a limited chemical analysis may serve only to confuse or deceive the cultivator in applying incomplete chemical data to their selection processes .…”

“…Several different reference materials were acquired for the purpose of compound quantitation and confirmation, as described in our previous work . A thirty-five-compound terpene analytical standard (LGC Standards) was used to quantify the major components in the samples.…”

“…3-Mercaptohexanol, 3-mercaptohexyl acetate, 3-mercaptohexyl butyrate, and 3-mercaptohexyl hexanoate (Excellentia, >97%) were prepared in hexanes. Senecioates were synthesized in-house (>97%) as previously reported and prepared in hexanes Table S1 shows the complete list of standards used and their calibration statistics.…”

“…The cultivation of Cannabis sativa L. has rapidly evolved over the past few decades, resulting in varieties with highly diverse morphological, chemical, and sensory characteristics. − Apart from the medicinal use of cannabis and the need for pharmaceutical-grade cultivars (i.e., genetic stability and reproducibility), there is a desire to influence cannabis offspring to produce unique secondary metabolite profiles. , Cannabis ’ vast genetic diversity enables a spectrum of aromas ranging from sweet, savory, or prototypical. ,,− In particular, many cultivators aim to produce varieties that express unique aromatic and flavor characteristics that can significantly impact consumer preferences …”

“…Volatile organic compounds (VOCs) make up part of cannabis’s secondary metabolite profile and are responsible for the aroma it produces. , These compounds are found in different plants, fruits, and vegetables. − In cannabis , the aromatic compounds discussed often include monoterpenes, sesquiterpenes, and their respective terpenoids. However, recent studies show that low-concentration compounds such as volatile sulfur compounds and recently discovered flavorants (nonterpenoid-derived VOCs) are the primary source of the unique and diverse aromas produced by cannabis . , While these compounds are known in the context of aroma identification, they have rarely been studied in the framework of selective breeding. For instance, minimal studies exist comparing the secondary metabolite profiles of cannabis progeny .…”