Industry uses two routes. The first isolates high-purity glycosides from dried stevia leaf by water extraction, resin separation and recrystallisation (INS 960a). The second starts from that extract and modifies it by enzymatic conversion, enzymatic glycosylation or microbial fermentation, producing materials with different sweetness and mouthfeel (INS 960b-960d).
Route A - leaf extraction (INS 960a)
| Step | Operation | What it does |
|---|
| 1. Extraction | Hot water, or water-ethanol | Glycosides dissolve readily in water and aqueous ethanol but poorly in pure organic solvents - the chemical basis of the water route |
| 2. Clean-up | Flocculation, centrifugation, membrane filtration | Removes protein, polysaccharides and pigments |
| 3. Resin separation | Macroporous adsorption resin, water-ethanol gradient elution | Components differ in polarity, so they adsorb and desorb in a different order |
| 4. Demineralisation and decolourisation | Ion-exchange resin plus activated carbon | Carbon adsorbs residual pigment; ion exchange removes inorganic salts |
| 5. Finishing | Concentration and crystallisation, or spray drying | Purity above 95% requires recrystallisation; high grades such as RA97 are often crystallised several times |
Table 1 - Route A, five steps from dried leaf to high-purity glycosides (INS 960a).
Route B - bioconversion and fermentation (INS 960b-960d)
| Route | Code | What happens |
|---|
| Enzymatic conversion | INS 960c | Glycosyltransferases change where the sugar units attach, converting the natural glycosides into sweeter components such as Reb M and Reb D. Natural steviol glycosides are the substrate; the product is sweeter with a cleaner finish. |
| Enzymatic glycosylation | INS 960d | One or more glucose units are attached to the glycoside - this is GSG. Cyclodextrin glucanotransferase (CGTase) catalyses the reaction with starch or dextrin as the donor. The added glucose raises water solubility and rounds the sweetness curve, at a slight cost in sweetness intensity. |
| Microbial fermentation | INS 960b | Engineered microorganisms produce the glycosides directly from glucose as carbon source, through the steviol biosynthesis and glycosylation enzymes, without leaf material. |
Table 2 - Route B. Products of all three routes may appear on an ingredient list as “steviol glycosides”, yet they carry different additive numbers in international specifications.
Where GL Stevia sits. Our production covers Route A leaf extraction (INS 960a) and enzymatic conversion (INS 960c), including the low-temperature dual-enzyme glycosylation process used for our Melis GSG series. We do not operate a microbial fermentation route (INS 960b).
The practical consequence for buyers: products from these routes may all be labelled “steviol glycosides”, but they are different food additives with different numbers in international specifications. Test methods, label wording and export documentation all differ.
Related products: Optimvia Reb-M / Reb-D · Reb-A Series · GSG Series