Effect of hot air and infrared drying on the retention of cannabidiol and terpenes in industrial hemp (Cannabis sativa L.)

This study aimed to investigate the drying effects on the retention of cannabidiol and terpenes in the industrial hemp (Cannabis sativa L.). Hemp inflorescence and leaves from Pipeline, Maverick and Queen-Dream-CBD varieties were dried with hot air (40, 50, 60, 70, 90 degrees C), and sequential infrared and hot air drying (infrared preheating for 1 and 2 min, then hot air drying at 40 and 60 degrees C). Ambient air drying and freeze drying were conducted as control groups. As the drying temperature increased from ambient to 90 degrees C, drying time reduced from 1800 to 210 min, cannabidiolic-acid conversion increased from 0.2%-14.1%, and total terpene retention decreased from 82.1%-29.9%. The total cannabidiol retention (ranging from 83.8%-98.6%) was affected by the drying methods and conditions. The findings suggested that drying conditions should be tailored to the requirements of the final products, which provides important information to the industry for improving the postharvest drying, downstream processing and product development.