ABSTRACT
Stevioside, extracted from the leaves of Stevia rebaudiana Bertoni, is a natural, high intensity, lowcaloric
sweetener with wide therapeutic activities. Conventional stevioside extraction methodologies
involve the use of non-green solvents, supercritical fluids, microwaves, etc., however, all these
processes are expensive, time-consuming and eco-unfriendly. Therefore an alternative process is
desired for the isolation of stevioside. In this study, a novel enzyme-mediated extraction (EME)
method has been developed. The dry stevia leaves were pre-treated with hydrolytic enzymes
aided by transition metal salts (FeCl3). This was followed by pressurized hot water extraction
(PHWE) to release stevioside. The crude extract was purified and clarified through multi-stage
membrane filtration. The results confirm that metal salt-assisted cellulase pre-treatment enhanced
the yield of stevioside to 72%, with 98% purity, which was higher in comparison to existing
methods. Thus, the methodology developed establishes a simple, “green”, enzyme-mediated
process for the efficient isolation of stevioside under economical and eco-friendly conditions.