Effect of outdoor and controlled environment drying on quality of hemp flower grown for cannabidiol

This is a presentation recorded at the 2023 joint conference of the Society for Economic Botany and Society of Ethnobiology, held at Emory University in Atlanta, Georgia from June 4-9, 2023.

#ethnobotany #ethnobiology #science #cannabis #cannabinoid #terpene #hemp #cannabidiol

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Effect of outdoor and controlled environment drying on quality of hemp flower grown for cannabidiol
Noelle Joy, Timothy Coolong, Daniel Jackson

Mature industrial hemp (Cannabis sativa) flower grown for cannabidiol (CBD) production was subjected to four different drying treatments and evaluated for cannabinoid profile, terpene yield and composition, moisture loss and change in trichome morphology. Drying treatments included gravity oven drying at 40 °C and 50 °C, drying in an open-air barn in Watkinsville, Georgia, and in a controlled environment chamber maintained at 15.5 °C and 60% relative humidity. Cannabinoid concentrations were not affected by drying treatment, but terpene yield and composition were affected. Oven dried hemp flowers had lower total terpene quantities than the barn and controlled environment dried hemp. For drying rates, oven dried hemp took an average of 26 hours at 40 °C and 18 hours at 50 °C, to dry from 73% to 10%, while barn and controlled environment drying took 5 to 6 days to reach the same moisture level. Data suggests that differences in phenotype among varieties, specifically the density of leaves, influenced the rate of drying. Scanning Electron Microscopy images were taken of hemp flowers before and after drying. There was a noticeable difference in the morphology of multicellular stalked glandular trichomes between fresh and dried hemp, with the dried hemp exhibiting a desiccated appearance with trichomes more densely packed due to water loss. However, there were no visual differences in trichome morphology among drying treatments.