Phenolic content and antioxidant capacity of yacon (Smallanthus sonchifolia) tuber flour

Yacon is a native plant of the Andean region of South America, from the sunflower family that has large tuberous roots. Studies regarding functional properties of tuber extracts have shown yacon tubers to have, among other properties, antioxidant capacity (Yan et al., 1999; Simonovska et al., 2003). The research work presented herein entails the characterization of the phenolic content and antioxidant capacity of extracts of yacon tuber flour obtained via different extraction conditions. The best extract from yacon tuber flour was obtained by boiling with deonized water for 10 min at a percentage of 23.4 %(w/v), dry weight, exhibiting a total antioxidant capacity of 1.710 +/- 0.109 g L-1 ascorbic acid equivalent and 1.559 +/- 0.135 g L-1 gallic acid equivalent. Phenolic composition was determined by LC/MS/MS and the analyses revealed the presence of four main phenolic compounds: chlorogenic acid, caffeic acid, coumaric acid and protocatechuic acid.