Decaffeination removes nearly all the caffeine from the beans. It is carried out while the beans are still ‘green’, before they are roasted.
Under European law decaffeinated coffee must contain 0.1%, or less, caffeine in roasted coffee beans, and up to 0.3%, or less, in soluble/instant coffee.
Decaffeination takes place in food manufacturing facilities. The process involves:
- Swelling the green coffee beans with water or steam so the caffeine can be extracted
- Extracting the caffeine from the beans.This is done with water, a solvent or activated carbon.
- Drying the decaffeinated coffee beans back to their normal moisture level.
Besides water,thesolvents typically used during decaffeination are ethyl acetate,methylene chloride (Dichloromethane, or DCM) or supercritical CO2.
Although manufacturing processes may slightly differ from one factory to another, generally where solvents are used, the water or the solvent is circulated around the water soaked beans and this causes the caffeine to be released. Then the mixture is drained from the extracting vessel and the process is repeated several times, until only a tiny amount of caffeine is left in the bean. All processes are carefully controlled so that any possible solvent residues remain below the strict limits fixed by law.