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• A novel method was developed to use solid CO 2 for supercritical fluid extraction (SFE). • The method involves controlled expansion of solid CO 2 in a stirred hermetic vessel. • P-V-T curves were obtained to relate solid CO 2 loadings to final supercritical conditions. • Batch supercritical CO 2 extractions of cannabis threshing residues were carried out. • Extraction yields were similar to those obtained in commercial SFE equipment. The change in the existing regulations in different countries regarding cannabis crops management and trading has enabled the commercial exploitation of the plant parts and of their extracts, metabolites and derivatives. Industrially, key metabolites such as cannabinoids and terpenoids are commonly extracted from the flowers by using supercritical CO 2. However, supercritical units require an extremely high capital investment even at low production capacities becoming a main drawback for exploratory and de-risking research stages. In this direction, this works aims to assess a low-cost CO 2 supercritical extraction technique for exploratory experiments employing solid CO 2 (known as dry ice) within a high-pressure vessel. By heating the solid CO 2 within the vessel, supercritical conditions can be achieved enabling extraction and recovery of the extract by subsequent depressurization. P-V-T curves were experimentally obtained to determine the required dry ice loadings to achieve specific supercritical conditions. Evaluated ranges corresponded to temperatures in-between 291 and 365 K, specific molar volumes of 47–90 mL/mol and the corresponding pressures ranging between 54 and 300 bar. Subsequently, the developed technique was validated in the lab-scale for the supercritical extraction of cannabis sativa threshing residues at CO 2 loadings of 0.63–0.73 g/mL, temperatures between 313 and 343 K and the corresponding pressures of 91–176 bar. The proposed technique enabled extraction yields of 3.9–6 % wt. with respect to dry biomass, with cannabinoids contents in extracts of 191.86 mg/g for CBD and 28.48 mg/g for THC. Results were comparable with those obtained in commercial supercritical equipment. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Extraction of cannabis flowers and leaves with cryogenic ethanol was carried out. • A bench scale rotary tumbler extractor was use and compared with soxhlet extraction. • Extraction efficiency of ∼22% of cannabinoids and terpenes was verified. • Lower content of chlorophyll and other impurities observed at cryogenic conditions. • Extraction can be suitably done at −20 °C and 15:1 solvent:solid ratio. Extraction of natural products using safe, selective and green solvents is of major importance for their use as ingredients in foods, beverages, cosmetics and pharmaceutical products. In the particular case of cannabis, ethanol at ambient conditions has been found to be very effective in the extraction of cannabinoids, terpenoids, and other valuable metabolites; however, it also extracts chlorophyll, vegetable oils and waxes. Alternatively, the selectivity towards cannabinoids could be increased by operating at lower temperatures. In this regard, this work focused on the cryogenic extraction of leaves and flowers of Cannabis sativa L. with ethanol. Extractions were carried out in a rotary tumbler under batch operation at different temperatures (−80 °C to 20 °C) and solvent:solid ratios (4:1 to 25:1 mL/g). The content of cannabinoids in samples was measured via U-HPLC under isocratic elution using a mixture of a 0.1% wt. formic acid aqueous solution and pure acetonitrile, using a diode array detector at 280 nm, and with an external standard method. Terpenes were quantified by GC using headspace injection, FID detection, and using external standards for calibration. The yields with respect to dry biomass were in-between 0.43% and 4.22% wt. The corresponding cannabinoids content with respect to dry material ranged from 0.25% to 2.67% wt., and these mainly corresponded to cannabidiol and cannabinol. The content of terpenoids was in between 0.01 and 1% wt., and the major fraction corresponded to monoterpenes d-Limonene, β-Myrcene, α-Terpinene, Terpinolene, and p-Cymene. Cryogenic extracts were characterized by a translucent aspect with minor content of coloring compounds and other impurities. Preferred operating conditions corresponded to −20 °C and a solvent:solid ratio of 16:1 mL/g; under these conditions and with respect to dry biomass, the extraction yield was 3.47% wt., the cannabinoids content was 0.67% wt., and the CBD content was 0.59% wt. [ABSTRACT FROM AUTHOR]