Sugar and glucose decolorization with activated carbon
How cane sugar refineries and starch sweetener plants use powder and granular activated carbon to remove colour, odour and impurities from liquors and syrups.
VMS Carbon technical team · 2 min read · Updated 31 October 2026
Sugar liquors and glucose syrups are naturally coloured by compounds formed during processing. Activated carbon removes that colour, together with odour and other impurities, to give a clear, white product.
What causes the colour
- Melanoidins, from Maillard reactions between sugars and amino compounds.
- Caramels, from heating sugars.
- Plant pigments and phenolic compounds carried over from cane or beet.
These are mostly large molecules, which is why carbons rich in mesopores do this work best.
Decolorizing edible oil
- Dark oil in the bleaching tank
- A small dose of wood powder carbon goes in
- Mixed, then filtered out in a filter press
- Light, clear oil comes out
Cane sugar refining
In refining, raw sugar is melted, clarified (by carbonatation or phosphatation) and then decolorized. Activated carbon is one of the decolorizing steps, used as:
- Powder carbon dosed into the liquor and filtered out, common in smaller refineries.
- Granular carbon in columns, used by larger refineries and regenerated in a kiln.
Carbon reduces colour (measured in ICUMSA units) and also removes odour and surface-active impurities that cause foaming.
Glucose, dextrose and other syrups
Starch-based sweeteners (glucose, dextrose, maltodextrin, high-fructose syrups) are polished with activated carbon to remove colour, flavour, hydroxymethylfurfural and protein traces before ion exchange and evaporation. Powder carbon in a stirred tank followed by filtration is common; granular columns are used in continuous plants.
Operating conditions
- Temperature: liquors are usually treated warm (around 70 to 80 °C) for lower viscosity and faster adsorption.
- pH: colour adsorbs better at slightly acidic to neutral pH.
- Contact time: 20 to 60 minutes for powder; set by tests.
- Dose: commonly a few tenths of a percent on dry solids; a dose-colour curve from a lab test sets it.
Grade selection
- High methylene blue and molasses decolorizing numbers point to the mesopores that colour needs.
- Acid washed grades limit ash and metals entering the product.
- Wood-based powder is a strong first choice for syrups; granular coal or coconut carbon suits regenerating column plants.
Send us your liquor type, colour and throughput and we will suggest a grade and dose to trial. Request a quote.
Frequently asked questions
Does activated carbon change the taste of sugar?
It improves it by removing off-flavours. The carbon itself is filtered out completely.
Can carbon replace ion exchange in syrup refining?
No. Carbon removes colour and organics; ion exchange removes salts. Most plants use both.
What is an ICUMSA unit?
A standard measure of sugar colour based on light absorbance; lower numbers mean whiter sugar.
