Search

The supercritical extraction of stalks and leaves of Eichhornia crassipes was carried out using pure and modified carbon dioxide. Preliminary results evidenced that the influence of temperature is weaker than pressure and ethanol content, and thus a design of experiments was performed in the ranges of 200–300 bar and 0.0–5.0 wt.% ethanol. The optima conditions for total extraction yield ( η Total ) were 250–300 bar and 5.0 wt.% of cosolvent, while for sterols yield ( η TotalSterol ) they were 300 bar and 2.5 wt.%. The latter conditions were also the most favorable to maximize the concentration of total sterols in the extracts ( C TotalSterol ), particularly stigmasterol ( C Stigm ), the most abundant one. For the referred optima, η Total = 1.25 wt.%, η TotalSterol = 0.35 wt.%, C TotalSterol = 38.26 wt.%, and C Stigm = 26.35 wt . % . This study showed also that the individual trends of stigmasterol and cholesterol were closer to the total sterols fraction behavior than β-sitosterol did, and also that the sterols concentration were higher in the first 2 h of extraction. In the whole, this article provides a pertinent contribution for the valorization of E. crassipes biomass through the production of natural extracts with high contents of sterols, especially stigmasterol, mainly if one takes into account it is classified as the most problematic invasive plant worldwide. [ABSTRACT FROM AUTHOR]

Moringa oleifera tree is found in many tropical areas, and its seed contains up to 40% of good quality edible oil where sterols are also present. In this work a techno-economic study encompassing the coproduction of oil and sterols from M. oleifeira seeds was accomplished using the RSM–COM approach. The oil is produced by subcritical fluid extraction (SFE) while the purification of the associated sterols is accomplished by a patented technology based on distillation. Besides the expenses and investment associated to the SFE, the respective costs and investment for the preliminary drying of biomass and final separation of sterols from bulk oil were also taken into account. Under optimized extraction pressure and time of 350 bar and 1.3 h, respectively, oil cost was estimated to be 2.76   €   k g oil − 1 for a SFE unit comprising two extractors of 1 m 3 capacity. For the coproduction of sterols with 89.4 wt.% purity, the minimum costs were 5.60   €   k g sterols − 1 . The overall annual production under optimum conditions was 558.9 tons of oil and 1.9 tons of sterols, leading the whole integrated process to a net income of 15.87 M € year −1 . In conclusion the proposed combined process is feasible, and this essay opened the way to exploit M. oleifera by subcritical fluid extraction under the scope of biorefinery premises. [ABSTRACT FROM AUTHOR]