TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Process: The plant material is dried at 20-50 C. The dried plant material is extracted while heating by injecting the steam directly or indirectly to 50-120 degreesC at a steam pressure of 1 - 8 kg/cm2 for 0.25 - 4 hours. The precipitate is separated by filtration. The plant material is charged into an extraction tank with or without water. The plant material is dipped in water for up to 1 day in the ratio of 1:1 - 1:30. The dry or wet plant material is extracted by by directly injecting steam for 0.25 - 4 hours to maintain an overall temperature to 50 - 100 degreesC. The wet plant material is extracted by indirectly injecting steam for 0.25 - 4 hours to maintain an overall temperature to 50 - 100degreesC. The plant material is heated by directly injecting steam on it in a continuous or non-continuous mode. The plant material is extracted for 1 - 3 times by directly injecting steam till ratio of plant raw material to cumulative water extracts falls to 1:10 - 1:30.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The aqueous extract is treated with a basic salt containing divalent cation selected from calcium hydroxide, calcium oxide and calcium chloride. The aqueous extract is basified at pH 8 - 10 to obtain a precipitate. The base treated filtrate is treated with neutral alumina to remove coloring impurities. The ion exchange resin is a strongly acidic type ion exchange resin or weakly basic ion exchange resin and is selected from gel type or macroporous type. The anion exchange treated steviosides solution is treated with neutral alumina to remove coloring impurities. The neutral alumina is washed with water before treating the stevioside solution. EXAMPLE - Stevia leaf powder (1 kg) of 200 - 400 mesh sizes was extracted with water (3x4 l) at 70 - 80degreesC. The extract was cooled and filtered on a Wattman 40 filter paper. The filtrate having 40% dissolved solids was treated with aqueous calcium hydroxide (50 g in 50 ml distilled water) till the pH was attained to 9.5 at room temperature and stirred for half an hour to obtain a precipitate. The precipitate was removed by filtration and the clear filtrate was passed through previously washed and equilibriated strong cation exchange resin (Tulsion T-42MP, macroporous type) and then through a weak anion exchange resin (Tulsion A2-XM13 macroporous type). The two resin beds were packed into glass column separately. The flow rate in the two resins was maintained at 2 bed volumes per hour. The eluant coming out of anion exchanger column was concentrated to get purified steviosides having 65.5% stevioside in the end product.