Purification of the by-product of the stevioside extraction process

Caramel is the by-product of the sweeteners extraction process of Stevia rebaudiana Bertoni leaves. This by-product shows significant contents of the sweeteners stevioside and rebaudioside A not extracted in the process and large quantity of leaf components, that give it, respectively, sweet flavor and dark color. Like this, the retreat of the leaf components of the caramel makes possible its reuse as a sweetener. Therefore, the caramel was purified by adsorption in modified zeolites, CaX and MgX. Two experiments were accomplished: a test of saturation of the adsorbents to evaluate its adsorption capacity and a test for maximum clarification to determine the maximum purification reached by adsorption in zeolites. Starting from the results, it was verified that CaX is a more effective adsorbent. Zeolites can be reused up to twice, needing regeneration soon after. The test for maximum clarification showed almost clear solutions, with high clarification levels (80-90% of the compounds with larger likeness), but with high retentions of the sweeteners (~70%), because zeolites retain most of the pigments of the caramel solution, but they also drag stevioside and rebaudioside A, resulting in a process with low yield in relation to the recovery of the sweeteners, but considered satisfactory, in view that caramel, in spite of being rich in sweeteners, has no use at present.

stevioside; rebaudioside A; adsorption; zeolites