Below are four of the most popular decaf processing methods. Swiss Water method, MC method, C02 method and the Sugarcane EA process.
The Swiss Water method
The Swiss Water process is an organic, 100% chemical-free option for decaffeination. It was discovered in the 1930s in Schaffhausen, Switzerland, and is commercialised by the Swiss Water Decaffeinated Coffee Company Inc, founded in 1988.
This method does not require the addition of chemicals, instead relying on a super saturated green coffee solution called Green Coffee Extract (GCE).
To decaffeinate coffee, fresh GCE is introduced to a batch of green coffee. As the GCE is already saturated with all the water-soluble compounds found in green coffee, minus the caffeine, the matching molecules won’t diffuse out of the coffee beans—but the caffeine will. The flavour is retained in the beans while the caffeine is removed.
Thanks to some scientific smarts and creativity, it’s possible to have decaf coffee that tastes the same – just without the caffeine!
The MC method
Methylene chloride (MC), also known as dichloromethane, is a volatile chemical solvent with a very low boiling point of 40°C. This is far below the roasting temperature of coffee, which is a little over 200°C, meaning that the methylene chloride is vapourised well in advance so that none (or a negligible amount) is left in the finished product. Though it does leave a slight sweet process taste to the final product.
The MC method is an ‘indirect’ solvent method, where the unroasted beans are soaked in near-boiling water for several hours before the water is transferred to another tank with the methylene chloride. The methylene chloride bonds with the caffeine in the water and is skimmed from the solution. The caffeine-filled solvent is removed, and then the flavoursome, almost caffeine-free water is put back in the first tank where it is reabsorbed by the beans. This process is repeated numerous times until 95-97% of caffeine is removed. This is opposed to the method of steaming the beans to open their pores, then soaking them directly in solvent.
The CO2 method
The CO2 method was developed by Kurt Zosel of the Max Planck Institute only recently. Liquid CO2 (carbon dioxide) is used instead of chemical solvents. Water-soaked coffee beans are placed in a container known as an extraction vessel, the vessel is sealed and liquid CO2 is forced into the container at pressures of 1000 pounds per square inch.
At this pressure, the CO2 extracts the caffeine by dissolving it. The caffeine-rich CO2 is then transferred to another chamber, where the pressure is released, allowing the CO2 to become a gas again. This is then separated from the caffeine using charcoal filters, clean and ready to be reused.
The CO2 method is ordinarily used to decaffeinate large quantities of commercial-grade coffee.
Ethyl Acetate or "Sugarcane" process
Green coffee is steamed for 30 minutes which opens the pores of the coffee, ready for caffeine extraction. Coffee is put into a solution of Ethyl Acetate (EA) which is a solvent sometimes derived from the fermentation of sugarcane – and known for its sweet taste. Once the coffee is saturated, the tank is drained and a fresh solution is introduced, this is done for another eight hours. Then the coffee is given a final steam which removes most of the EA.
We sell Swiss Water Decaf because we believe it is the best, 100% chemical free, which means the taste of the coffee is not impaired by any outside flavours.
We are also launching our own range of DRWakefield Swiss Water Decaf coffees – a Sourced Collection. Which you won’t be able to find anywhere else. Keep a look out for them as we gradually introduce them into the market.