In a new study, researchers at Cornell University have examined how postharvest drying and curing methods impact the cannabinoid content and microbial levels in industrial hemp.
Published in the journal Plants, the study analyzed three drying techniques—hot air drying at 75°C, ambient air drying at 25°C, and freeze drying—followed by curing in sealed glass jars or mylar bags under dark conditions at room temperature.
The results indicate that hot air drying can reduce hemp moisture from 77% to a safe storage level of 6% within eight hours while also achieving up to a two-log reduction in total yeast and mold counts. In contrast, ambient air drying took one week, and freeze drying required 24 hours. Curing increased hemp moisture by 3.3% to 13.6%, but the method used did not significantly impact results.
While neither drying nor curing significantly altered total cannabinoid content, both processes contributed to decarboxylation and reduced greenness.
“The findings suggested that hot air drying followed by glass jar curing is preferred for higher drying efficiency, better preservation of the cannabinoids and microbial safety”, concludes the study.
