Optimization of extraction conditions for ultrasound-assisted extraction of phenolic compounds from tamarillo fruit (Solanum betaceum) using response surface methodology

The study intended to optimize the ultrasound-assisted extraction of phenolic compounds using response surface methodology as optimization tool. Initially, four solvents, namely, distilled water, ethanol, acetone and methanol at 100% concentration level were tested for extraction of total phenolics and acetone was found to be the best solvent. Individual experiments were performed to determine the best possible range for extraction time, solvent (acetone) concentration and ultrasound amplitude in the extraction process. Box-Behnken design with three independent variables of extraction time (5–15 min), ultrasound amplitude (20–60%) and solvent concentration (50–80%) were taken to maximize total phenolic content, total flavonoids content and DPPH radical scavenging activity that were taken as dependent variables. Quadratic model in response surface methodology was found to be significant. Extraction with acetone at 73 and 78% concentration and ultrasound amplitude of 43 and 46% were optimum for red and yellow tamarillo, respectively. Optimized extraction time was found to be 12 min for maximum phenolic content, flavonoids content and DPPH radical scavenging activity with the desirability of 0.94 and 0.97 for yellow and red tamarillo, respectively.