Ultrasonic bath assisted extraction of total polyphenols and betalains from dragon fruit peel: Optimization by Box–Behnken design

This study aims to optimize the conditions for ultrasonic bath-assisted extraction of betalains, polyphenols, and antioxidant compounds from dragon fruit peel (Hylocereus undatus). A Box-Behnken design was employed to evaluate the factors of sonication time, temperature, and ethanol percentage used as a solvent. The results showed that the optimal conditions for betalain extraction were a sonication time of 24 minutes, a temperature of 26°C, and 48% ethanol. For total polyphenols, the optimal time was 80 minutes, the temperature was 53°C, and the ethanol percentage was 54%. Antioxidant compounds exhibited optimal extraction conditions with a time ranging from 72 to 80 minutes, a temperature of 70°C, and an ethanol percentage between 54% and 56%. No significant differences (p ≤ 0.05) were observed between the optimal experimental values and the theoretical ones, indicating that the optimized extraction factors reliably predict extraction yields. This study contributes to maximizing the use of bioactive compounds present in dragon fruit peel, adding value to the fruit while enabling the development of new functional foods derived from this by-product, which is typically discarded in industrial processes.