The solubility of cannabis constituents plays a major role with respect to their processing (extraction/fractionation), product formulation, and interaction with packaging materials. Here we have applied thermodynamic solution theory as a framework to optimize the above processes for the two major cannabis/hemp constituent groups: the cannabinoids and terpenes. Solubility parameter theory (SPT), phase equilibria and activity coefficients have been applied to both pressurized fluid- and liquid-based extractions as well as subsequent processing steps such as decarboxylation, extraction, dewaxing, phase separation, solvent devolatilization, and fractionation. This approach can be applied when using pressurized fluids - such as carbon dioxide and butane - and liquid solvents such as ethanol. Solubility and phase equilibria measurements can also be used to rationalize recorded experimental extraction data for both critical fluids and liquid solvent media - particularly with respect to their sequential use in extractions and separations in both the near critical and supercritical state. For the major cannabinoid components found in cannabis and hemp extracts, SPT and corresponding states theory (CST) predict low cannabinoid solubility at pressures &lt;25 MPa and temperatures of 40-80 C, their solubility maximum occurring at high extraction pressures (70-90 MPa), or a solubility parameter ~ liquid ethanol. SPT and CST can also be used to rationalize the observed phase separation behavior of cannabinoids, wax and lipid constituents, and terpenes. For example, the binary CO<sub>2</sub> –terpene systems (limonene and beta-carophyllene) exhibit solubility minimum between 8-9 MPa and 60 C and similar phase behaviors can be used to separate terpenes from plant wax material between 3-7 MPa and 0-40 C. These same theoretical principles can also be applied to understanding the formulation of cannabinoid-terpene infused products in a variety of matrices, and their phase separation, as well as choice of stable packaging material-cannabis/hemp combinations utilizing SPT, and Flory-Huggins polymer-solute chi interaction parameters.

A physicochemical approach for optimizing the solubility, extraction, fractionation, and packaging - cannabis constituents

ACS Spring Meeting 2021

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