Enrichment of the rebaudioside A concentration in Stevia rebaudiana extract with cyclodextrin glycosyltransferase from Bacillus licheniformis DSM 13

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.

Engineering of cyclodextrin glycosyltransferase improves the conversion efficiency of rebaudioside A to glucosylated steviol glycosides and increases the content of short-chain glycosylated steviol glycoside

“…Therefore, a high degree of glucosylation will also affect the taste and quality of the catalytic products (glucosylated steviol glycosides). As the main components of steviol glycosides are stevioside (ST) and rebaudioside A (RA) [ 10 , 11 ], the detection indexes to evaluate the advantages and disadvantages of mutants were determined as the conversion rate of ST and RA to glucosylated steviol glycosides and the content of short-chain glycosylated products [ 20 , 21 , 26 ]. Amino acid residues near the substrate binding sites were preliminarily selected for mutation.…”

“…Since 2008, steviol glycosides has been approved by the World Health Organization Joint Expert Committee on Food Additives and other official organizations as a food and drug additive [ 9 ]. The main components of steviol glycosides are stevioside (ST) and rebaudioside A (RA) [ 10 , 11 ]. Unfortunately, the bitterness of RA and ST is detected by half of the human population [ 12 ].…”

Efficient Bioconversion of Stevioside and Rebaudioside A to Glucosylated Steviol Glycosides Using an Alkalihalobacillus oshimesis-Derived Cyclodextrin Glucanotransferase

“…Thus, steviol glycosides are formed on a common aglycone and steviol and differ only in the glycosidic constituents attached to C13 and/or C19 [ 11 , 12 ]. Studies have shown that the number of glucosyl groups attached to C13 and/or C19 considerably affects the taste profiles of steviol glycosides [ 11 , 12 , 13 ]. The two major sweet components of steviol glycosides are Stev and Reb A [ 13 ].…”

“…Studies have shown that the number of glucosyl groups attached to C13 and/or C19 considerably affects the taste profiles of steviol glycosides [ 11 , 12 , 13 ]. The two major sweet components of steviol glycosides are Stev and Reb A [ 13 ]. Stev was first discovered as the primary sweet component in Stevia leaves; however, it exhibited a strong bitter aftertaste [ 6 , 14 , 15 , 16 ].…”

“…Cyclodextrin (CD) glucanotransferase (CGTase; EC 2.4.1.19) belongs to the α-amylase family 13 of glycoside hydrolases (GH13_2). With starch as the glycosyl donor, CGTase can transform steviol glycosides into glucosylated steviol glycosides [ 12 , 13 , 17 , 18 , 19 , 20 , 21 , 22 ]. The efficiency and components of the catalytic products of CGTase considerably affect the quality of glucosylated steviol glycosides.…”