The present study was embarked upon for the optimization of conditions aimed at ultrasonic assisted extraction (UAE) of antioxidant chemicals from Moringa oleifera leaves by applying response surface methodology (RSM) based on face centered central composite design (CCD). Evaluation was done at three levels (20 experimental designs) with three process variables: extraction temperature (20, 30, 40oC), extraction time (20, 30, 40 min) and liquid-solid ratio (20:1, 30:1, 40:1) using probe sonicator. The extraction process optimization based on RSM was focused on the capacity of antioxidants present in the extracts to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) free radicals. To envisage the optimization process, multiple regression analysis was carried out using RSM tool to obtain a quadratic polynomial equation. Stastical analysis of the factors and their interactions were tested using analysis of variance (ANOVA). Extraction of antioxidants was mainly influenced by liquid-solid ratio and temperature. The ideal combination of variables designed by RSM for maximum radical-scavenging activity was optimized with extracting temperature of 39.80 °C, extracting time of 39.95 min and liquidsolid ratio of 24.00 mL/g to obtain a predicted value of 85.528% of DPPH radical-scavenging activity, which was very close to the experimentally value of 86.49 % with an error of 1.12%, indicating suitability of the model.
Optimization of simultaneous microwave/ultrasonic-assisted extraction of phenolic compounds from walnut flour using response surface methodology
