In this study the composition of the stevia extracts obtained in different stages of the process in a pilot unit of extraction and purification was monitored by high performance chromatography (HPLC) analyzes. The permeate from the nanofiltration step that has been discarded as residue was sampled and subjected to analysis to determine its antioxidant potential and its composition by UHPLC-MS / MS-QTOF. The permeate showed 58% of phenolic compounds and 3.3% of steviol glycosides. In this fraction, ten phenolic compounds, with high potential to be uses as food or food additive were identified. Considering that expressive volumes of this compounds are generated during the purification of stevia sweeteners, its recovery could be important in order to make better use of the substances with functional effects present in stevia leaves.
Key words: Stevia rebaudiana, sweeteners, UHPLC-MS / MS-QTOF, nanofiltration.