Study of stevioside preparation by membrane separation process

Abstract

In this paper, advantages of stevioside preparation by membrane separation process are described. The test results showed that it is feasible to substitute membrane separation technology for heat-evaporation process. Because there is no phase-change in membrane separation process, it basically keeps freshness, fragrance and tasty of original material, and avoids the sugar-carbonizing, denaturing and colority deepening caused by heat-evaporation. In addition, the membrane separation process has advantages of high efficiency and Low energy consumption. After precipitated and decolorized, aqueous stevioside solution was further decolorized and purified by ultrafiltration (UF), and then concentrated by reverse osmosis (RO). Generally, the stevioside solution can be concentrated up to a Baumé degree of above 10, and 90 percent of water or more can be removed, i.e., each set of RO device ( with a membrane area of 13 M 2) can remove water of 0.4–-0.6 ton per hour (at operating pressure of 3 Mpa). stevioside powder can be obtained through spray-drying of concentrated solution. From viewpoints of economic profit, labor strength and work environment, etc., membrane separation process is superior to other ones for stevioside preparation.