Decaffeinated coffee now accounts for around 10% of worldwide coffee sales. If you
drink coffee on a regular basis, you may sometimes choose decaffeinated coffee
over standard – but have you ever wondered just how the process works?
Coffee is a natural product, and it contains many substances which all contribute to
the complex flavour and aroma. Caffeine is just one ingredient among many, and the
problem faced by manufacturers is to remove it without compromising all the other
substances and thus affecting the flavour. There are several possible methods, all of
which treat the green coffee beans prior to roasting.
The first commercially successful method was invented in 1903, and involved
steaming the coffee beans then washing the caffeine out with a solvent. A method
still in use today by small local producers is Swiss Water Processing, which involves
soaking the beans in hot water. Once the caffeine has dissolved into the solution,
the beans are thrown away, and the solution is filtered through carbon to remove the
caffeine.
The decaffeinated solution is then used to soak a new batch of green coffee beans.
As the solution already holds the maximum amount of other coffee compounds from
the original beans, but contains no caffeine, only the caffeine from the new batch
filters out. The process is repeated several times using the original solution, which is
continually filtered to remove the caffeine, until the maximum amount of caffeine has
been extracted from the new beans, which are then dried and roasted as usual.
EU standards dictate that coffee sold as ‘decaffeinated’ must be at least 99.9%
caffeine free by mass, so sometimes the beans have to go through the process
ten or twelve times, making decaffeinated coffee expensive to produce. However,
there’s good news for decaff lovers – scientists have discovered a coffee bean that’s
naturally low in caffeine, which could have a big impact on the decaffeinated coffee
industry, making your daily decaff as full of flavour as regular coffee.