Ultrasonic _assisted extraction of phenolic compounds with evaluation of red onion skin (Allium cepa L.) antioxidant capacity.

This study aimed to determine the antioxidant activity of red onion peel extract using ultrasound extraction. Antioxidant activity was evaluated using DPPH, inhibition of β-carotene, ABTS and FRAP. The results indicated that the 130 W ultrasound power, in pulsed mode, and with 60% solvent favored flavonoids and total anthocyanins, FRAP and β-carotene. The highest levels of total phenolics were found using 60% solvent, at 130 W, and in continuous extraction mode. DPPH was influenced only by the 60% solvent, and the ABTS values were higher with the 80% solvent, in pulsed mode, and at 130 W of power. [ABSTRACT FROM AUTHOR]