Effect of Drying Methods on Phytochemicals and Antioxidant Activities of Stevia Rebaudiana Bertoni

Abstract

This research aimed to study the effects of the different drying methods on total phenolic compounds, flavonoid, stevioside and antioxidant activities of Stevia Rebaudiana Bertoni. The experiment involved in four different drying methods: sun drying, air drying, hot air oven drying at temperatures of 40 °C, 50°C, 60°C, and 70 °C, and microwave drying at power levels ranging from 100 to 800 watts. The result indicated that the choice of drying method had a significant impact (p<0.05) on total phenolic compounds, flavonoid, stevioside and antioxidant activities. Among the various drying methods, the microwave drying at 450 watts exhibited the highest levels of total phenolic compounds (48.82 mgGAE/ g DW), flavonoid (18.80 mgQE/g DW), stevioside (8.75 g/100 g DW), and antioxidant activities compared to the other drying methods. Therefore, drying the Stevia Rebaudiana Bertoni leaves using a microwave at 450 watts was determined to be the optimum condition, as it effectively preserved the active compounds with strong antioxidant potential.