What are the decaffeination methods?

Four main processes coexist: the Swiss Water Process (water plus activated charcoal, no chemical solvent), supercritical CO2 (gas under high pressure), natural sugarcane ethyl acetate, and the direct dichloromethane process. All must leave less than 0.1 % residual caffeine under European rules.

Industrial decaffeination was first patented in 1903 by German merchant Ludwig Roselius, using benzene — a solvent since abandoned for toxicity reasons. Four methods dominate today, each with its own logic. The Swiss Water Process, patented in 1933 and industrialised in Canada from the 1980s, soaks green beans in water pre-saturated with coffee solubles (Green Coffee Extract). Only caffeine migrates out by osmotic gradient, is then trapped on activated carbon, and the water is recirculated. No chemical solvent touches the bean. Aromatic yield is usually good; cost is high.

Supercritical CO2, pioneered at the Max Planck Institute in the 1970s and industrialised by Kraft in Germany, brings CO2 to 70-100 bar and 40-60 °C. In that intermediate state between liquid and gas, CO2 diffuses into the bean's pores and selectively captures caffeine while leaving most aromatics untouched. Capital expenditure is heavy, which is why it mostly appears inside large multinationals. Natural ethyl acetate, often sold as 'sugarcane EA' or 'EA natural', is produced from fermented cane molasses, mostly in Caldas and Quindío in Colombia. EA is a compound found naturally in many fruits (apples, bananas); it dissolves caffeine after the beans are soaked in hot water.

The fourth route, labelled 'direct' or 'indirect' depending on the variant, uses dichloromethane (DCM) or synthetic ethyl acetate. DCM long dominated Europe; it is still allowed in the EU with a maximum residue of 2 mg/kg of roasted coffee, a threshold considered safe by EFSA. It is cheaper and less energy-hungry than supercritical CO2, which is why it persists in the commodity segment. Sensory results differ: Swiss Water and sugarcane EA tend to keep fruity and floral notes of specialty lots better, while chemical solvents tend to flatten the cup. In Belgium, demand for specialty decaf grew during the 2020s, particularly in Brussels, Ghent and Antwerp micro-roasters.

Decaffeination methods compared