Optimization of microwave-assisted extraction using response surface methodology and HPLC-DAD phenolic compounds quantification from <i>Hylocereus undatus</i> peel and pulp cultivated in Tunisia

The present study aimed to optimize the microwave-assisted extraction process for both the peel and pulp of <i>Hylocereus undatus</i> (white dragon fruit) cultivated in Tunisia, using response surface methodology. Total phenolic content, total flavonoid content, FRAP (ferric reducing antioxidant power), and DPPH (1,1-diphenyl-2-picrylhydrazyl) antioxidant activities were optimized. A central composite design (CCD) was applied, considering three key variables: extraction time, extraction temperature, and liquid-to-solid ratio. The optimized extraction parameters for <i>Hylocereus undatus</i> peel and pulp were determined respectively (9.57 min, 42.20 °C and 27.79 mL/g) and (10.08 min, 40.84 °C and 31.52 mL/g). The main phenolic compounds identified in <i>Hylocereus undatus</i> peel and pulp extracts using HPLC-DAD were chlorogenic and caffeic acids and rutin, quercetin, luteolin-7-<i>O</i>-glucoside as flavonoids. Therefore, this research has revealed the potential of a sustainable and eco-friendly process hold promise a directional option and encouraging a circular economy approach for industrial production of antioxidant-rich <i>Hylocereus undatus</i> extracts.