The primary extract is then clarified either by flocculation or electro-coagulation. For purification by flocculation, the extract is treated with flocculants like Calcium hydroxide, Aluminum hydroxide, Alum, Calcium carbonate, Ferric chloride etc. This flocculants precipitates the gummy and resinous polysaccharides, proteins and plant pigments.
In the electrocoagulation method, aluminum electrodes are dipped in the extract and they are connected with low voltage high current power source. The flow of electric current through the extract coagulates the gums, resins and pigments and makes the extract clear.
After this stage, the extract is freed from the coagulated material by filtration. Generally, common plate and frame filters are used in this stage.
The next step is separation of solid glycosides from liquid extract. Clarified liquid extract from this stage can be processed by to entirely divergent technologies. Follow the appropriate link to learn more about the technologies
Large scale electrocoagulation setup for clarification of aqueous extract of stevia
Electro-coagulation process live