Improvement of extraction and purification of stevioside and its products from Stevia rebaudiana
1997
Nittaya Ngowatana
Suitable method for extraction and purification of stevioside and its products from Stevia rebaudiana consisted of three steps; water extraction at 55 deg C using ratio of dried stevia:water = 1:10, purification by depigmentation of impurities with 40 percent of Ca(OH)2 (based on total soluble solids of extract) and FeSO4.7H2O that was equimolar to Ca(OH)2 and demineralization in ion exchange chromatography column packed with Amberite 200 (strongly acidic cation exchange resin). The extract was dried in the lyophilizer. Stevioside and its products were white fine powder and highly hygroscopic. It must be kept in air-tight package to prevent moisture adsorption. In large scale production the same methods were used, except the final step that produced dry products by using spray dryer. 3,000 grams of stevia could obtain 101.56 grams of light yellow fine powder of stevioside and its products. Product compositions were stevioside 40.32 grams (39.70 percent and 1.34 percent based on product weight, and stevia; respectively). The amount of iron and calcium were 0.97 and 1.47 milligrams per gram of product; respectively. The moisture content of the product was 9.31 percent. The product was highly hygroscopic.
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