Optimization of eco-friendly ultrasonic probe-assisted extraction from Stevia rebaudiana Bertoni using response surface methodology and antioxidant evaluation
Gizem Yıldırım Baştemur, Reyhan Akpinar, Emir Bora Taşçı, Beyza Pirdal, Nazlı Kılağuz, Furkan Kütükçü, Tuğsan Tenekeci, Merve Boyraz, Sabriye Percin OzkorucukluAbstract
In this study, an environmentally friendly ultrasonic probe-assisted extraction (UPAE) method was modeled and optimized to enhance the recovery of rebaudioside A, resveratrol, and total phenolic content (TPC) from Stevia rebaudiana Bertoni using response surface methodology. A central composite design was applied to investigate the effects of extraction time (1–9 min), ethanol concentration (0–100 %), plant amount (0.1–0.5 g), and ultrasonic frequency (20–28 kHz). Extraction efficiency was evaluated through TPC analysis and quantitative determination of rebaudioside A and resveratrol by high-performance liquid chromatography (HPLC). Green chemistry principles were integrated into extraction and analytical procedures by employing ethanol as a sustainable solvent and eliminating toxic organic modifiers. Optimal conditions were determined as 7 min extraction time, 75 % ethanol, 0.2 g plant material, and 22 kHz frequency. Under these conditions, rebaudioside A, resveratrol, and TPC were obtained as 281.59 μg/mg, 5.74 μg/mg, and 54.17 mg GAE/g, respectively, showing strong agreement with model predictions. The optimized extract exhibited high total flavonoid content and antioxidant capacity as confirmed by DPPH, FRAP, and CUPRAC assays. The proposed UPAE–HPLC approach provides a sustainable and efficient platform for the recovery of natural sweeteners and antioxidant compounds from Stevia rebaudiana , with potential applications in food, nutraceutical, and pharmaceutical industries.