The Majority Of Recent Studies Use Greener Extraction Processes Such As Sd And Hd

By Author: doris zhang
Total Articles: 78
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Triterpenes have been extracted from cannabis roots and stem bark through CSE, using polar solvents. On one hand friedelin and epifriedelin were isolated from cannabis roots after an ethanolic extraction . On another hand, cannabis stem bark were shown to contain small quantities of various triterpenes, identified from an acetone soxhlet extract . No optimization of the extraction was performed for the recovery of terpenes nor triterpenes of EO from cannabis roots, although a deeper knowledge of CSE of triterpenes in particular may provide a better view for a potential valorization of these compounds. Supercritical Fluid Extraction is an environmentally friendly extraction technique that uses a flfluid in its supercritical state for the extraction process. CO2 is by far the most used fluid to perform SFE. This has many advantages such as chemically stable, low toxicity, cannabis grow equipment not flammable and inexpensive. Another reason is its low critical temperature and pressure for the safe extraction of thermolabile components and its easy separation from the sample during ...
... the depressurization step of the process.

Supercritical CO2 is a good solvent for the extraction of volatile compounds such as terpenes from C. sativa . SC-CO2 extraction was compared to HD in two studies.Both works concluded in a better EO yield in the SFE extract than in the HD extract. The use of SC-CO2 has great advantages in comparison to HD, such as the absence of damaged compounds with the use of low temperature, the direct recovery of the EO and the possible fractionation, similar to those done in the works of Da Porto et al. and Vági et al.,with the isolation of volatile compounds from other extracted components.Moreover,according to SC-CO2 extraction would exhibit lower energy consumption compared to hydrodistillation.The focus is on the effect of temperature and pressure in all studies of C. sativa inflorescence terpene extraction with SC-CO2.Da Porto et al. studied the influence of the extraction pressure on the yield and composition of hemp EO. At 40 ◦C, an increase in extraction pressure from 100 bar to 140 bar leads to a decrease in the EO yield, from 0.67 w% DW to 0.34 w% DW, respectively. In addition, the authors observed that the terpene repartition in the extract at 100 bar is closer to the original inflorescence composition. A lower monoterpene content and higher sesquiterpene content have been noticed in the extract at 140 bar.This different profifile is probably induced by a change in the components’ solubility in SC-CO2 due to the increase in pressure. According to Naz et al.,an increase in temperature from 40 ◦C to 45 ◦C enables a better cannabis EO yield; however, further temperature increase causes a lower yield. The authors also varied the pressure when increasing the temperature, it is thus difficult to attribute this result to the sole temperature factor. Another study used a design of experiment to optimize the SC-CO2 extraction of terpenes and cannabinoids from cannabis.

The authors claimed that the use of low temperature and no co-solvent favors the extraction of volatile compounds.The influence of extraction pressure is not mentioned.However,the optimal conditions include an extraction pressure of 100 bar which is consistent with the previous cited work.SC-CO2 is also used for the recovery of cannabinoids from cannabis,present in the same plant organs than terpenes.Interestingly, a sequential extraction is possible, where the terpenes are extracted without any co-solvent. A second step consisting in the addition of ethanol as co-solvent enables the extraction of cannabinoids.Up to 1.5 g/100 g DW of volatile compounds have also been recovered from cannabis in a separate fraction from cannabinoids. This time, the extract is fractioned in a fifirst separator retrieving the cannabinoids fraction while a second one recovers the terpene fraction . The studies reported here provide interesting perspectives for the SC-CO2 extraction of terpenes from C. sativa, where low pressure, low temperature and no co-solvent are preferred. Furthermore, the fractionation or sequential extraction are good ways to valorize the entire extract Cannabis sativa L. is a controversy plant due to the psychoactive content of the drugtype cultivars. However, the hemp type gets increased interest due to the numerous bioactive compounds contained in its by-products.Besides the well-known cannabinoids present in cannabis inflorescences,PC and terpenes extracted from hemp deserve particular attention.After reviewing the available articles on the extraction processes of PC from C. sativa, we noted a dominancy of UAE and CSE techniques.This means that even though CSE has several disadvantages such as long extraction time and a use of large amount of solvent,it is still frequently used by researchers for its simplicity. Furthermore, due to their low cost, CSE equipment are available in all laboratories. On the other hand, the development of intensified extraction processes such as UAE is under study. This technique is of particular interest due to its numerous benefits including the increase in extraction yield and faster kinetics compared to CSE .

When optimized, UAE offers the best results in 20 min while extractions often last 3 h in the case of CSE. Other intensifified processes such as MAE and ASE have also been used for the extraction of PC from cannabis. Once again, the signifificant improve lies in the extraction time, reduced to minutes. Not surprisingly, all techniques converge on the use of polar solvents, with aqueous acetone being the most effificient. However, based on the identifified studies, further developments are needed for their application on the recovery of PC from hemp. Indeed, many authors have focused on intensifying the process without defifining the applied operating conditions. For example, the temperature has a clear inflfluence on PC recovery,mobile grow system but was sometimes not mentioned. The ultrasonic or microwave power shall also be chosen with care knowing the risk of PC degradation. The comparison with and without intensifification seems then diffificult without defifining the objective of PC recovery. The most studied parts of the plant are the hemp seed meal and the inflflorescences. These parts are considered as by-products obtained after the extraction of seed oil and fifibers. Therefore, research is focused on theirvalorization by identifying secondary metabolites having biological activities. In this context, PC has interesting potential. Some of the most valuable identifified phytochemicals are cannflflavins, N-trans-caffeoyltyramine, and cannabisins. However, stilbenoids presented in Section 2.1 have only been recorded in few PC extracts.