Extraction of total flavonoids from the outer covering of red onion (Allium cepa)

Abstract

The purpose of this work was to quantify total flavonoids, expressed in quercetin, of red onion outer covering. Onion samples were acquired from the peasant ecological market in Cali city (Valle del Cauca). Methanol extracts were performed by using shaking, ultrasound and UVC (ultrasound, vortex, and centrifugal). Frozen samples and room temperature were used. The most efficient method was determined. Presence of flavonoids was qualitatively identified, and total flavonoids concentration, expressed in quercetin, was quantified through ultraviolet. The best results were obtained for frozen samples, by using UVC method. Quantification through ultraviolet led to achieve reproducible concentrations in average of 178,4307 mg/l, for frozen extracts, and 70,1590 mg/l for room temperature extracts, obtained from red union covering.