US Patent 7923552: High yield method of producing pure rebaudioside A

1. A method of purifying rebaudioside A from Stevia starting material comprising: (i) formulating a selected EtOH solvent consisting of water and ethanol, (ii) performing a first reflux stage by refluxing the Stevia starting material in the selected EtOH solvent and optionally performing additional reflux stages using retentate isolated from a refluxed mixture or from a stirred wash mixture, (iii) optionally, performing one or more stirred wash stages, and (iv) performing an ethanol purge and drying stage,
wherein formulating a selected EtOH solvent comprises either (A) a reflux solvent approximation, wherein, based on the asserted or labeled purity of a batch of Stevia starting material, for a Stevia starting material labeled or asserted to be 90% rebaudioside A purity, the reflux solvent is formulated as ethanol and water, and for every 5% decrease in rebaudioside A purity below 90% rebaudioside A purity in the Stevia starting material, based on the asserted or labeled purity of a ba