Evaluation of antioxidant activity of steviol glucoside commercial powder in neutral and acidic pH

Abstract

Introduction. Current trends on new food products aim to incorporate biopolymers to improve their physicochemical stability, such as Stevia rebaudiana. Furthermore, due to its high sweetening potential, commercial steviol glucoside (CSP) powder has been recently incorporated into food formulation for its antioxidant capacity. Objective. This study focused on the evaluation of antioxidant capacity of commercial steviol glucoside powder, under both neutral and acidic pH conditions (3.5-7) at concentrations ranging from 100-500 µg/mL. Material and Methods. Tests were assessed in triplicate for a sample of CSP, available in Algeria, by using 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging method (DPPH). Total phenolic compounds were measured in 100µg with Folin-Ciocalteu. Results. Commercial powder of steviol glucoside presented a total polyphenols content of 2.500±0.0150 mg/g of CSP dry weight, and exhibited a significant inhibitory percentage of DPPH. Values were ranged of 35.89±0.16% to 62.32±0.45% in neutral pH, and were between 40.21±0.04% to 65.00±0.26% in acidic pH. Data showed that inhibitory concentration IC50 against DPPH was ranged of 208.204 µg/mL in neutral pH, and 269.547 µg/mL in acidic pH. Conclusion. Commercial stevioside powder can be used not only as sweetener, but also as poly-phenols source with antioxidant activity in the preparation of neutral and acidic low calorie functional foods.