Steviol glycosides and polyphenols extraction from Stevia rebaudiana Bertoni leaves using maceration, microwave-, and ultrasound-assisted techniques

Optimization of steviol glycosides and polyphenols extraction from stevia leaves for maceration, microwave-assisted (MAE) and ultrasound-assisted (UAE) techniques were performed by investigating the effects of process variables using response surface methodology. Optimum extraction conditions for maceration were 50% EtOH concentration, 118 mL/g solvent ratio, 54°C temperature, and 112 min extraction time. Optimum operation temperatures and extraction times for MAE and UAE were estimated as 51°C & 16 min and 50°C & 43 min, respectively. MAE and UAE significantly reduced processing time as compared to maceration. A total of 65 compounds were identified by LC/Q-TOF/MS analysis.