Abstract
Stevia rebaudiana is a sweet herbaceous perennial plant, which is frequently used in the preparation of plant-based sweeteners. The demand for such sweeteners continues to increase due to purposeful nutrition and modern-day metabolic syndromes. More than 20 types of steviol glycosides provide a sweet taste, which are more than 300 times sweeter than sucrose. They are formed of two main components, namely stevioside and rebaudioside A. Only a handful of studies have dealt with Stevia rebaudiana leaf extracts, the conversion of pure stevioside into the preferred rebaudioside A is more common. The aim of this study was to enrich the rebaudioside A content of Stevia rebaudiana leaf extract using enzymatic bioconversion by applying fermented cyclodextrin glycosyltransferase from Bacillus licheniformis DSM13. Two differently processed plant materials, namely dried and lyophilized Stevia rebaudiana plants, were extracted and compared. Following the bioconversion, the rebaudioside A content was on average doubled. The maximum increase was fivefold with a 70-80% conversion of the stevioside.