Decaffeinated Coffee Beans
Coffee Decaffeination Process
Decaffeinating coffee is achieved through a variety
of decaffeination processes, all of which are relatively harmless
to your health, but harmful to coffee quality.
Almost every process for decaffeination consists of soaking the beans in water to dissolve the caffeine,
extracting the caffeine with either a solvent or activated
carbon, and then re-soaking the coffee beans in the decaffeinated
water to reabsorb the flavor compounds that were lost in
the initial extraction. The solvents typically used
are methylene chloride or ethyl acetate, which both have
a low boiling point. Since ethyl acetate is found
naturally in fruits you will hear people call this process
"natural." In any case the solvent never
comes in contact with the coffee bean itself, but only the water
solution containing the caffeine that was previously extracted
from the coffee bean. Therefore the water decaffeination process is relatively
benign. All methods used to decaffeinate coffee are based on
equilibrium principles and solvent/solute properties.
As such, neither all of the caffeine is removed from the
coffee, nor are all of the flavor compounds returned or
left in the coffee. The chemical composition of decaffeinated
coffee (or decaf coffee) is altered, and therefore the flavor and aroma are
changed.
How to Decaffeinate Coffee
Swiss Water Process
In the Swiss Water Process, the green coffee beans
are soaked in hot water to remove the caffeine and compounds
responsible for much of the flavor of the coffee flavor.
The first batch of coffee beans is then discarded, while the caffeine
is stripped from the solution by means of activated carbon
filters. This leaves a solution saturated with flavor
compounds, which is then used to soak a new batch of decaffeinated green
coffee beans. The principle of water procesed decaf coffee is that the solution is saturated
with all components soluble in water other than caffeine. Therefore, only the caffeine in the bean is allowed to
escape whereas the rest of the compounds are in equilibrium.
Unfortunately, the flavor of batches is intermixed since
the chemically saturated solution is used repeatedly.
CO2 Process
In the carbon dioxide decaffeination process, green coffee beans
are soaked in highly compressed CO2, which extracts
the caffeine. The caffeine is then removed from the
CO2 using activated carbon filters, which are then reused
to extract caffeine from the coffee again.
Sparkling Water Process
The sparkling water decaffeination process is similar to
the CO2 method, but instead of removing the caffeine
with activated carbon filters, the caffeine is washed from the CO2
with sparkling water in a secondary tank, which is then recycled to extract
more caffeine from the coffee. The solvent consists
of approximately 99.7% compressed carbon dioxide and 0.3%
water.
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