Utilisation of QSPR ODT modelling and odour vector modelling to predict Cannabis sativa odour

Abstract

Cannabis flower odour is an important aspect of product quality as it impacts the sensory experience when administered, which can affect therapeutic outcomes in paediatric patient populations who may reject unpalatable products. However, the cannabis industry has a reputation for having products with inconsistent odour descriptions and misattributed strain names due to the costly and laborious nature of sensory testing. Herein, we evaluate the potential of using odour vector modelling for predicting the odour intensity of cannabis products. Odour vector modelling is proposed as a process for transforming routinely produced volatile profiles into odour intensity (OI) profiles which are hypothesised to be more informative to the overall product odour (sensory descriptor; SD). However, the calculation of OI requires compound odour detection thresholds (ODT), which are not available for many of the compounds present in natural volatile profiles. Accordingly, to apply the odour vector modelling process to cannabis, a QSPR statistical model was first produced to predict ODT from physicochemical properties. The model presented herein was produced by polynomial regression with 10-fold cross-validation from 1,274 median ODT values to produce a model with R2 = 0.6892 and a 10-fold R2 = 0.6484. This model was then applied to terpenes which lacked experimentally determined ODT values to facilitate vector modelling of cannabis OI profiles. Logistic regression and k-means unsupervised cluster analysis was applied to both the raw terpene data and the transformed OI profiles to predict the SD of 265 cannabis samples and the accuracy of the predictions across the two datasets was compared. Out of the 13 SD categories modelled, OI profiles performed equally well or better than the volatile profiles for 11 of the SD, and across all SD the OI data was on average 21.9% more accurate (p = 0.031). The work herein is the first example of the application of odour vector modelling to complex volatile profiles of natural products and demonstrates the utility of OI profiles for the prediction of cannabis odour. These findings advance both the understanding of the odour modelling process which has previously only been applied to simple mixtures, and the cannabis industry which can utilise this process for more accurate prediction of cannabis odour and thereby reduce unpleasant patient experiences.

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

“…This is in alignment with recent sensory studies that have developed a diverse lexicon to adequately describe the aroma of many cannabis varieties. 14 , 21 , 31 , 38 To ensure that we captured many of the different aromas that cannabis produces, we procured 31 ice hash rosin samples of different varieties ( Table S2 ) to build a robust catalog of compounds beyond terpenes.…”

“…High-tetrahydrocannabinol (THC) varieties of Cannabis sativa L., often referred to as simply cannabis, are typically cultivated for consumption due to their intoxicating psychoactive effects. − Low-THC Cannabis sativa L. (<0.3% THC), referred to as hemp, is primarily grown for the production of cannabidiol (CBD) and its utilization in textiles fibers . In particular, the high-THC cannabis industry has grown considerably over the past decade as legalization increases. − During this time, consumer expectations have evolved concomitantly, with tetrahydrocannabinol (THC) content in particular proven to be a key driver in the industry, resulting in a race to continuously increase cannabinoid concentration. ,, Nevertheless, consumer preference is also influenced by the aromatic qualities of a product. , This has led to terpenes–a general term that when used within the industry describes a multitude of compounds that produce the aroma of cannabis – to emerge as secondary differentiators within the marketplace, leading to their routine testing at analytical laboratories. ,− This phenomenon is partially in response to the commonly used, but inaccurate, classification of cannabis as either indica, sativa, or a hybrid of the two major species of Cannabaceae. ,, These terms have historically been used to categorize cannabis based on their physical, aromatic, and psychoactive characteristics, sativa varieties being tall and narrow-leaved with energizing effects and indica varieties being short and bushlike with broad leaves and sedating effects. , While this nomenclature is still commonly used, modern cannabis rarely fits into one of these two classifications and rather appear to be hybrids of the two, muddling their use in accurately differentiating cannabis varieties on a phenotypic, aromatic, or chemical level. , …”

“… 3 , 11 , 12 Nevertheless, consumer preference is also influenced by the aromatic qualities of a product. 13 , 14 This has led to terpenes–a general term that when used within the industry describes a multitude of compounds that produce the aroma of cannabis – to emerge as secondary differentiators within the marketplace, leading to their routine testing at analytical laboratories. 11 , 15 − 20 This phenomenon is partially in response to the commonly used, but inaccurate, classification of cannabis as either indica, sativa, or a hybrid of the two major species of Cannabaceae .…”