Study of the interactions of bioactive compounds and antioxidant capacity of an exotic fruits beverage that sweetened with stevia

A functional beverages, with a high content in bioactive compounds, based on exotic fruits (mango juice, papaya juice and acai) mixed with orange juice, oat and sweetened with different concentrations (0, 1.25 and 2.5%w/v) of Stevia rebaudiana (Stevia) extracts, a natural source of non-caloric sweeteners (steviol glycosides) were formulated and studied. Ascorbic acid, total carotenoids, total phenolics, anthocyanins, total antioxidant capacity (TEAC and ORAC methods) and steviol glycosides were evaluated. Beverages sweetened with 1.25 and 2.5% (w/v) Stevia showed a significant increase (3-fold and 4-fold higher, respectively) in phenolic compounds as well as in antioxidant properties in comparison with the beverage without Stevia. The displayed results indicate the potential use of Stevia as an alternative non-caloric sweetener in the preparation of beverages based on fruit juice mixtures and oat, as it may provide good nutritional and physicochemical properties and also enhance the already existing beneficial effects of fruit juices. Synergistic interactions observed between phytochemicals and steviol glycosides in the complex food beverages when TEAC method was used suggest an improved solubility or stability of antioxidant compounds and hence, the combined antioxidant capacity measured by TEAC assay is potentiated in the complex food matrix.