Stevia rebaudiana stevioside from

Fig. 103.1 Major steviosides from Stevia rebaudiana Bertoni (Adapted from Rajasekaran et al. [12])...

Potential widespread use of steviosides requires an easy and effective extraction method. Enzymatic extraction of stevioside from Stevia rebaudiana leaves with cellulase, pectinase, and hemicellulase, using various parameters, such as concentration of enzyme, incubation time, and temperature, has been reported [33]. Purification is achieved through adsorption, colunm chromatography, and ion-exchange electrolytic technique for rebaudioside A, rebaudioside C, and dulcoside A [34]. An ultrafiltration (UF) process was reported for recovery of 45 % steviosides from an extract of leaves. Final purification was achieved by two consecutive mixed bed ion-exchange processes. The ion exchangers improved purity of the final product to 90 % [35]. 

Let us mention that in the popular sweetening products isolated from Stevia rebaudiana, the two components of principal interest for the sweetening properties are two CSC-type compounds, namely stevioside (62) and rehaudioside A (63). ... 

Stevia sweeteners are extracted from the leaves of Stevia rebaudiana Bertoni (Compositae), an herb native to Paraguay but cultivated in Southeast Asia, Japan, Paraguay, Brazil, Israel, and the United States. The sweet constituents of stevia include eight diterpene glycosides stevioside, ste-violbioside, rebaudiosides A, B, C, D, E, and dulcoside A, which collectively are 100-300 times... 

Stevioside is used as a sweetener in Far Eastern markets and in some South American countries. It is extracted from the leaves of Stevia Rebaudiana... 

Stevioside or stevia [XI] is the name given to a group of sweet diterpene glycosides extracted from the leaves of Stevia Rebaudiana plant (native of South America). Steviosides show good stability in the solid form. They are also quite stable in acidic condition beverages at 22°C. Steviosides are approved for food use in several South American and Asian countries, but lack approval in Europe and North America. 

Stevioside is an ent-kaurene type diteipenoid glycoside isolated from leaves of Stevia rebaudiana Bertoni. Leaves of this plant produce zero-calorie diterpene glycosides (stevioside and rebaudioside), a nmi-nutiitive, high-potency sweetener. Stevioside content in leaves will vary in field grown plants and is also influenced by agroclimatic conditions. Stevia leaves are also in use for their medicinal benefits. In this chapter, natural distribution and cultivation of Stevia,... 

Steviol glycosides are derived from the mevalonic acid pathway. The ent-kaurene skeleton of stevioside is formed via 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway [59, 60]. High activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase in chloroplasts of Stevia rebaudiana has been reported [61]. Hence, the investigators anticipated mevalonic acid (MVA) as an intermediate of steviol biosynthetic route on the basis of the fact that HMG-CoA reductase is a key enzyme of the MVA route to isopentenyl-diphosphate (IPP). 

Extraction of stevia sweeteners from dried leaves can be accomplished with acetonitrile in the presence of calcium carbonate solution (116) or with boiling water adjusted to pH 9.0 (107). Ahmed and Dobberstein (117) extracted stevioside and rebaudioside A and C from dried leaves of S. rebaudiana in a micro-Soxhlet apparatus. They observed that chloroform/methanol provided the best results, compared to chloroform or to chloroform/methanol/water. Extraction of stevioside, rebaudioside A and C, and dulcoside A can also be performed by subcritical fluid extraction using C02 and methanol as a modifier. Such an extraction technique has been gaining popularity as an analytical tool because it is rapid, simple, and less expensive in terms of solvent cost (110). Beverages, tabletop sweeteners, beverages containing pulp, and candies are prepared as indicated in Sec. I.C (110,115,118). 

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