Abstract

The antioxidant capacity of six herbal tea infusions (Mentha piperita, Erythroxylum coca, Rosa moschata, Tilia spp, Plantago major, and Aloysia citriodora) was measured by ORAC type methodologies employing fluorescein (ORAC-FL) and pyrogallol red (ORAC-PGR) as target compounds. Probe consumption profiles were widely different, with neat induction times when FL is employed as target. Relative ORAC values of different herbal infusions depend upon the test molecule employed. Relative ORAC-PGR values follow the order: Rosa moschata > Mentha piperita > Tilia spp > Plantago major > Aloysia citriodora >Erythroxylum coca, while ORAC-Fl values order is: Mentha piperita > Aloysia citriodora > Erythroxylum coca >Rosa moschata >Tilia spp > Plantago major. These differences are related to the different relevance of the parameters (amount of phenols and reactivity) that determine ORAC values for different target molecules. In particular, ORAC-FL values are associated with the polyphenolic levels present in the sample and, hence, correlate with the Folin index of the infusion. On the other hand, ORAC-PGR values are determined by the quantity and average quality of the antioxidants present in the tested sample. From these results, it is proposed that the ratio ORAC-PGR/ORAC-FL could be employed as a rough measure of the antioxidant average quality of the phenols present in the tested infusion.