High pressure extraction of olive leaves (Olea europaea): bioactive compounds, bioactivity and kinetic modelling

Abstract

In this study, the extraction yield, the mathematical modeling of pressurized liquid extraction (PLE) kinetics with sub-and supercritical carbon dioxide (SC-CO 2 ) of olive leaves (Olea europaea) and the biological activity of the extracts were evaluated. The extraction with PLE was conducted isobarically (10.3 MPa), varying the temperature (20, 40 and 60 °C) and the solvent (ethyl acetate, acetone, ethanol, ethanol:water-80:20, v:v), solvent flow (2 mL min -1 ) and time (110 min) and the extractions with SC-CO 2 , varying the temperature between 20 and 60 °C and the pressure between 8 and 25 MPa, keeping the time constant (210 min) and the CO 2 flow of 2 mL min -1 . In the extracts, antioxidant activity, total phenolic and flavonoid contents and oleuropein were evaluated. The highest total extract yield in the PLE was 30.91% at 60 °C, 10.3 MPa using ethanol:water (80:20, v:v). The yield obtained using the supercritical fluid was 0.68% at 60 °C and 25 MPa. The PLE extract obtained with ethanol at 60 °C presented the highest concentration of total phenolic content (386.42 mg GAE g -1 extract), total flavonoids content (33.43 mg CAT g -1 extract), oleuropein (73.65 mg g -1 extract) and antioxidant activity (82.87%). The overall extraction curves were modeled using the well-established Sovova ´model and kinetic extraction model based on the Brunauer-Emmett-Teller theory of adsorption. Both kinetic models used were able to correlate well with the experimental data with slightly better results obtained by the former. The alternative PLE extraction technique investigated in this work was found to be suitable for the extraction of olive leaves after short times of extraction obtaining an extract with high biological activities.

Innovative Extraction Technologies for Development of Functional Ingredients Based on Polyphenols from Olive Leaves

“…Analogously, PLE using an ethanol-water (60:40, v/v ) mixture at 190 °C for 5 min has been shown to be a viable technique for extracting oleuropein, luteolin-7 -O- glucoside, apigenin-7 -O- glucoside, quercetin, and verbascoside (up to 120, 4.65, 3.01, 0.75 and 2.23 g/kg dry weight, respectively) from olive leaves with a lower consumption of solvents and lower energy costs [ 53 ]. In a recent study, extraction with PLE was conducted isobarically (10.3 MPa), varying the temperature and solvent; the highest total extract yield (30.91%) was obtained at 60 °C using ethanol and water (80:20, v:v ), whilst the highest concentration of total flavonoids, oleuropein, and antioxidant activity (82.87%) was obtained at 60 °C using just ethanol [ 108 ].…”

Evaluation of physicochemical, bioactive composition and profile of fatty acids in leaves of different olive cultivars

“…The leaves have proven nutraceutical potential, being mainly used by the pharmaceutical industry, however the leaves or their extracts can also be incorporated into food products due to their characteristics. Among the bioactive compounds, simple phenolics, flavonoids and secairidoides stand out (Rosa et al, 2019;Talhaoui et al, 2015;Rahmanian et al, 2015).…”

Extraction kinetics and physicochemical characteristics of Colombian propolis

“…For ultrasound extraction, the phenolic content extracted after 30 min was within 85%-115% of the equilibrium concentration in between 300 and 600 min as in phenolic extraction, samples SR1 and SR2 showed a slow and steady increase in the concentration during the extraction (7 days). This suggests that, predominantly, flavonoids are located in internal pores, and thus, have slower diffusion kinetics (Rosa et al, 2019;Torun et al, 2015).…”