Decolorizing Stevia rebaudiana (Bert.) leaf extracts with activated charcoal and qualitative analysis of stevioside using chromatographic methods

Abstract

Abstract Background The Stevia rebaudiana (Bert.) leaves are natural low-calorie sweeteners used in many products, including foods, drinks, medicines, cosmetics, and more. This study aimed to use activated charcoal to remove color, purify stevioside from Stevia leaves, and utilize the chromatographic method to confirm its identity. Results We developed a novel eco-friendly method to decolorize and purify stevioside from Stevia leaf. The yield of stevioside was calculated by weighing the crystallized sample following freeze-drying. The average yield is 8.13%. Ultraviolet-Visible (UV-Vis) and Fourier Transform Infrared (FT-IR) spectroscopy were performed to confirm the identification. This purified sample showed a wavelength region of 4000–650 cm-1 in the FT-IR and a UV-Vis spectrum at 206.49 nm, which referred to it as a stevioside. In HPLC, the purified sample did an accuracy and precision test with standard stevioside, which gave a similar peak to the purified sample at the same retention time. According to High-Performance Liquid Chromatography (HPLC), the purity of stevioside is 98.12%. The pH effect on the decolorization of Stevia leaf extracts with activated charcoal was 5.5–8.0. Conclusion In contrast to other commercially available methods, the above process can inexpensively purify stevioside from Stevia leaves.