Pressurized liquid extraction of compounds from Stevia leaf: Evaluation of process variables and extract characterization

The extraction of compounds from Stevia rebaudiana leaves under pressurized conditions was investigated. The effect of the ethanol percentage in the extracting solvent, static time, pressure and temperature on global extraction yield (YGE), total phenolic content (TPC) and antioxidant activity (AA) was evaluated. The extract from pressurized liquid extraction (PLE) was characterized and compared to that obtained from Soxhlet and ultrasound-assisted extraction (UAE). It appears that the increase of ethanol concentration in the solvent favored response variables, while the increase in static time and pressure did not affect the extraction. The temperature (125 ºC) provided an increase in YGE and the highest levels of active compounds were obtained after using 70% (v/v) ethanol in the extracting solvent (15 mL g−1) and 30 min. The different techniques evaluated provided similar YGE, while PLE providing greater extraction of TPC and AA, and Soxhlet favored the extraction of steviol glycosides and total flavonoids. [Display omitted] •Increase of ethanol percentage in the solvent and temperature promoted the extraction.•Maximum yield, total phenolic compounds and antioxidant activity were obtained at 50 bar and 125 °C.•Degradation of compounds was verified at 150 °C.•An extract with ∼26.0 wt% steviol glycosides (48.5% rebaudioside A) was obtained.