Why decaffeinate something that is known for caffeine?
Caffeine is the most well known compound present in coffee beans, however at the last count more than eight hundred chemicals have been identified in coffee beans, many of which can lead to flavours, aromas and potential health benefits. It is for this reason that we decaffeinate coffee; so that consumers who are sensitive to caffeine can still enjoy the great taste and health benefits.
There are three main methods for removing the caffeine from raw coffee beans:
- Direct Solvent
- Indirect Solvent
- Carbon Dioxide
- Swiss Water
- In the first of these methods, the green coffee beans are steamed for approximately half an hour to open the pores and then rinsed with a liquid solvent (usually ethyl acetate or methylene chloride) for 10 hours to allow the caffeine to bind to the solvent. The beans are then removed from the solvent and steamed again to remove any remaining solvents.
- The indirect solvent method involves soaking an initial batch of the beans in hot water, which removes not just the caffeine but other oils and flavours too. The chemical solvent is then added to bind to the caffeine molecules and heated in order to evaporate the compound. Any remaining water is then used to process further batches of coffee - due to the water having the oils and flavours there will be no transfer out of the new beans in the same way.
- Carbon dioxide processing is the most recent method, and uses liquid CO2 in place of a solvent. Green beans are soaked in hot water as in the other methods but then CO2 is added at a very high pressure in order to attract the caffeine molecules and remove them from the beans. The liquid is then drawn off and un-pressurised allowing the CO2 to become a gas again, and be used for the next batch.
- Swiss Water Process (SWP), named after the country it was initially developed in, was not commercially viable until as recent as the 1980's. For this method, the coffee beans are soaked in hot water to dissolve the caffeine molecules, however this strips out the oils and other soluble compounds. In order to return them to the coffee, the water is passed through an activated charcoal filter to catch the caffeine molecules, but allowing other molecules through. The green beans are then returned to the caffeine-free water to reabsorb the oils and other dissolved items before being processed as normal.
Carbon Dioxide and Swiss Water Process are the main type that you will find in speciality coffee shops, however ehtyl acetate is still commonly used, when produced as a by product of fermented sugar cane. This method is becoming increasingly popular in countries such as Brazil and Colombia who are two of the largest producers in the world.
For those of you looking for a great decaf option we have a Colombia Cauca coming very soon, with notes of red berry, caramel and cocao.