Microwave-Assisted Industrial Scale Cannabis Extraction

Abstract

Cannabis is a flowering plant that has long been used for medicinal, therapeutic, and recreational purposes. Cannabis contains more than 500 different compounds, including a unique class of terpeno-phenolic compounds known as cannabinoids. Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are the most extensively studied cannabinoids. They have been associated with the therapeutic and medicinal properties of the cannabis plant and also with its popularity as a recreational drug. In this paper, an industrial method for cannabis extraction using 915 MHz microwaves coupled with continuous flow operation is presented. The main advantages of the microwave-assisted extraction (MAE) are associated to the continuous-flow operation at atmospheric pressure which allows for higher volumes of biomass to be processed in less time than existing extraction methods, with improved extraction efficiency leading to increased final product yields, improved extract consistency and quality because the process does not require stopping and restarting material flows, and ease of scale-up to industrial scale without the use of pressurised batch vessels. Moreover, due to the flexibility of changing the operation conditions, MAE eliminates additional steps required in most extraction methods, such as biomass decarboxylation or winterisation, which typically adds at least a half day to the extraction process. Another factor that sets MAE apart is the ability to achieve high extraction efficiency, i.e., up to 95% of the active compounds from cannabis biomass can be recovered at industrial scale.

Postharvest Operations of Cannabis and Their Effect on Cannabinoid Content: A Review

“…MW pre-treatments on rosemary leaves resulted in almost two times the phytochemical concentration during storage compared to the untreated leaves [ 50 ]. Phytocannabinoid extraction with the assistance of MW shows a significant improvement of the process output [ 51 , 52 , 53 , 54 ]. To prompt the drying process and to improve the polyphenol, cannabinoid, and terpene profile of cannabis, MW heating could be an ideal pre-treatment.…”

Extraction, Characterization, and Chitosan Microencapsulation of Bioactive Compounds from Cannabis sativa L., Cannabis indica L., and Mitragyna speiosa K.

“…Furthermore, the antioxidant capacities in terms of DPPH inhibition, ABTS inhibition, and FRAP capacity were also increased, as previously mentioned ( Table 1 ). The main downsides of the organic solvent approach are related to unsuitable materials, such as fats, waxes, and pigments, which dissolve along with the cannabinoids, as well as the extraction temperatures, which frequently cause the destruction of heat-sensitive compounds during processing [ 8 , 10 , 16 , 34 ]. In previous studies, selection criteria were based on solvent extraction, such as ethanol or methanol combined with microwave extraction.…”

“…Furthermore, the effects of microwave extraction processing differ from those of the organic solvent extraction method due to alterations in the cell structure by electromagnetic radiation during extraction [ 7 ]. Moreover, advances in microwave extraction have led to the development of cutting-edge processes, including vacuum microwave hydrodistillation, microwave Soxhlet extraction, microwave-assisted Clevenger distillation, etc., which are environmentally friendly methods that can be used to reduce energy use, time required for extraction, solvent use, and waste [ 10 , 39 , 40 ].…”

“…Microwave extraction can achieve high extraction rates accurate control for the extraction of bioactive compounds. The microwave procedure directly interacts with microwave electrical power to heat the solvent, which causes plant tissue to break down and release active compounds into the normalized solution (water), in addition to a significant increase in internal pressure [ 7 , 9 , 10 , 11 , 12 ]. In addition, maceration extraction has conventionally been used with solvent reagents in several studies, e.g., ethanol, methanol, acetone, ethyl acetate, dichloromethane, and hexane, to explore the extraction of polyphenolic compounds from plants [ 13 , 14 ].…”

A Comprehensive Review on the Techniques for Extraction of Bioactive Compounds from Medicinal Cannabis

“…Different conventional extraction methods, including Soxhlet extraction, maceration, and dynamic maceration, have been employed to extract phytochemicals from Cannabis [ 68 , 75 , 76 , 80 , 82 ]. However, studies have also revealed the caveats of using conventional extraction methods, such as the extraction of unwanted substances and degradation of heat-sensitive compounds due to extraction under high temperature [ 84 ]. As cannabinoids, phenolic compounds, and terpenes are the three main classes of secondary metabolites in Cannabis , the conventional extraction of these main classes is discussed further in the following subsections.…”