Pressurized Liquid Extraction of Cannabinoids from Hemp Processing Residues: Evaluation of the Influencing Variables

Abstract

Cannabinoids have gained significant interest as they may have pharmaceutical and nutritional applications to treat various diseases (sclerosis, glaucoma, and epilepsy, among others). Hemp (Cannabis sativa L.) has been studied recently as a source of cannabinoids, given the low concentration of tetrahydrocannabinol and comparatively high concentration of cannabidiol. Most of the plant’s fractions are used (blossoms, stem, and seeds), but the processing of the blossom leaves a residue, threshing residues, which could still be used to extract cannabinoids, aiming for an integral usage of the plant. Different technologies have been applied for cannabinoid extraction. Among these, pressurized liquid extraction (PLE) stands out due to the ease of application and efficiency. This work evaluates the influence of temperature, pressure, extraction time, and the number of cycles for the PLE of cannabinoids from hemp threshing residues using ethanol. Results show that low pressures, 100 °C, and 60 min are sufficient to achieve extraction yields of 19.8 mg of cannabidiol per g of dry hemp, which corresponds to an extraction efficiency of 99.3%. These results show this technology’s potential for cannabinoid extraction (mainly cannabidiol) and further open the perspective to valorize the residues and other parts of hemp plants.