Evaluating the potential of cell disruption technologies for green selective extraction of antioxidant compounds from Stevia rebaudiana Bertoni leaves

An increased interest has been shown by both food technologists and food industry regarding Stevia rebaudiana Bertoni leaves (Stevia) for their high content or bioactive components (phenolic compounds, vitamin C, carotenoids). The aim of this work was to study the effect of emerging technologies such as high voltage electrical discharges (HVED) and pulsed electric fields (PEF) and ultrasounds (US) on the intensification of the extraction of valuable compounds from Stevia leaves. The proposed processes combined pretreatment (HVED, PEF and US) and extraction of intracellular compounds using water as solvent at ambient temperature. The energy inputs of the treatments varied from 24 to 141 kJ/kg and the results were compared to control diffusion experiments. Chlorophyll a, and b, total carotenoid, total phenolic compounds and antioxidant capacity (DPPH) were determined. A significant increase in soluble matter and antioxidant compounds was found after HVED, PEF and US-assisted extraction as compared to control samples. Results showed that HVED, PEF and US treatments improved both kinetics and extraction yield of soluble matter. These results show the ability of HVED to be used as a potential technology to enhance protein recovery using water and avoiding the use of other solvents and grinding. Chlorophyll content was significantly higher (3-fold increase) after HVED assisted extraction at 141 kJ/kg in comparison to control sample (0.352 and 0.355 mg/L for chlorophyll a and b, respectively). The same energy input for HVED permitted attain highest extraction diffusivities of total soluble matter (D = 3.06 x 10(-09) m(2)/s), followed by total phenolic compounds (D = 2.60 x 10(-10) m(2)/s) and then proteins (D = 6.00 x 10(-11) m(2)/s). (C) 2014 Elsevier Ltd. All rights reserved.