Total antioxidant activity of yacon tubers cultivated in Brazil

Yacon (Smallanthus sonchifolius) is a tuberous root from the Andean region in the South America rich em water, fructooligosaccharides and phenolic compounds, some of which are natural antioxidants and may help prevent the deleterious action of free radicals in the body. The yacon has attracted much attention due to their potential health benefits to humans. In this study the levels of total phenolics, tannins, phenolic acids, and total antioxidant activity were measured in the peel and pulp of yacon tubers both in the fresh and flour forms. The flours of yacon presented higher concentrations of total phenolics and tannins, especially peel flour. The yacon pulp flour stood out as the main source of phenolic acids, mainly caffeic and chlorogenic acid. The total antioxidant activity assessed by DPPH (2,2-Diphenyl1- picrylhydrazyl) and ABTS (2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) assays was higher in the yacon peel flour. The total antioxidant activity was correlated with the total phenolic content and tannins by the DPPH and ABTS assays. These results suggest that yacon can be used as an alternative food source of phenolic compounds that help prevent degenerative processes caused by oxidative stress, especially in the flours form.