초록 ▼

An improved method for the recovery of stevioside from Stevia rebaudiana Bertoni plants is provided which does not require the use of dangerous chemicals or special separation equipment such as ion exchange or chromatography. In the process the raw material, preferably in comminuted form is first ex

An improved method for the recovery of stevioside from Stevia rebaudiana Bertoni plants is provided which does not require the use of dangerous chemicals or special separation equipment such as ion exchange or chromatography. In the process the raw material, preferably in comminuted form is first extracted with water, the resulting aqueous extract is treated with a di- or tricarboxylic acid chelating agent to remove metallic and other impurities as well as to lower the pH to less than about 4. Subsequently a calcium-containing agent is added to precipitate out other impurities. The aqueous extract is essentially neutralized with an acid and is then subject to extraction with a water-immiscible solvent. Purified stevioside crystals are recovered by cooling the water layer obtained from said solvent extraction step.

대표청구항 ▼

A method for the recovery of stevioside from leaves of Stevia rebaudiana Bertoni which comprises the following sequential steps: (a) contacting said leaves with hot water to obtain an aqueous extract containing stevioside; (b) admixing said aqueous extract with a chelating agent whereby the pH of th

A method for the recovery of stevioside from leaves of Stevia rebaudiana Bertoni which comprises the following sequential steps: (a) contacting said leaves with hot water to obtain an aqueous extract containing stevioside; (b) admixing said aqueous extract with a chelating agent whereby the pH of the aqueous extract is lowered to less than about pH 4 and metallic impurities are chelated and then separated from the aqueous extract; (c) contacting the thus treated aqueous extract with a base to precipitate salts of the chelating agent, protein impurities and colored impurities, and separating said precipitates from the aqueous extract; (d) treating the resulting aqueous extract, having a basic pH, with an acid essentially to neutralize the aqueous extract; (e) contacting the neutralized aqueous extract with a water-immiscible, organic solvent, and separating the resulting solvent layer from the aqueous layer; (f) cooling the aqueous layer to a temperature sufficient to crystallize stevioside therefrom; and (g) separating stevioside crystals from the cooled aqueous layer.