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

Abstract

Abstract The Stevia rebaudiana (Bert.) leaves are natural low-calorie sweeteners that are used in a wide range of products, including foods, drinks, medicines, cosmetics, and more. The current study aims to obtain high purity stevioside by first decolorizing the Stevia leaf extracts with activated charcoal, then purifying them with 70% ethanol and concentrating them in a rotary evaporator, respectively. The yield was then calculated by weighing the crystallized sample following freeze-drying. The average yield is 8.13%. According to High-Performance Liquid Chromatography (HPLC), the purity is 98.12%. The obtained stevioside was compared to standard stevioside and confirmed using UV-Visible and Fourier Transform Infrared (FT-IR) spectroscopy. The purified sample showed a wave number region of 4000–650 cm-1 in FT-IR and in the UV-Vis spectrum, a peak was found at a wavelength of 206.49 nm. An accuracy and precision test was done with a crystal sample, which gave a similar spectrum to the standard stevioside at the same retention time in HPLC. The pH effect on the decolorization of Stevia leaf extracts with activated charcoal was 5.5–8.0. In contrast to other commercially available methods, the aforementioned method can be used to produce pure stevioside from Stevia leaf extracts rapidly, simply, and, inexpensively.