Polyphenol input to the antioxidant activity of yerba mate (Ilex paraguariensis) extracts

Industrial processing modified the polyphenol content, composition and antioxidant activity of the yerba mate extracts. Pre-dried leaves were the most appropriate raw material combining maximum activity with high polyphenol content. Chlorogenic acid and its derivatives were the major components of the phenolic fraction but we also identified caffeic, rutin and quercetin. Yerba mate extracts inhibited malonedialdehyde formation in sunflower oil (20 mu mol/kg) and conjugated dienes production in oil/water emulsions (60 mu mol/kg). Enhancing the dose to 60 mu mol/kg reduced 27.8% the extract's activity in oil. The relationship between polyphenol composition and antioxidant activity of a mixture of caffeic, chlorogenic, kaempferol, quercetin and rutin was satisfactorily predicted with a polynomial model. Results showed that quercetin was the highest contributor to the linear term followed by kaempferol and caffeic acid while rutin and chlorogenic acid inputs were the lowest. The model detected five synergistic and six antagonistic effects. (C) 2011 Elsevier Ltd. All rights reserved.