Recently a variety of the coffee tree was discovered that naturally contains almost no caffeine. Until and
unless that species finds its way into commercial production, we're left with the current methods for
removing unwanted caffeine from coffee. But how do
those methods affect the taste of our java?
Blind taste tests suggest that most people can't really
tell the difference between decaf and regular, provided
both kinds are processed properly and the cup brewed
well. But, for those who can...
Among the methods for removing caffeine from coffee
is treatment with hot water, followed by rinsing in
Maybe you didn't know your coffee had already seen
water before you got to it? In fact, several times. The berries are rinsed after picking to soften the outer fruit
for removal, then rinsed again to help eliminate the remaining flesh.
And possibly you were unaware your grounds had taken a dip in the swimming pool before being served. (Ok,
swimming pool water is really dilute hydrochloric acid, not methylene chloride. Never let a chemist stand
between you and a good line.)
So, the taste difference is less likely to come from the presence or absence of caffeine as from any remaining
processing chemicals and whether they removed flavor-producing components.
Chemical removal of the caffeine from green, unroasted beans starts by warming them in hot water or steam.
That opens the bean's pores. Then the beans are rinsed in methylene chloride, which binds to the caffeine and
is then flushed away.
Alternatively, the beans can be soaked for several hours in hot water, where the caffeine leaches out into the
bath. The beans are removed and methylene chloride introduced to the bath. There it bonds with the caffeine,
not the flavored components that have washed out of the bean. The beans are then soaked again where they
reabsorb the flavor compounds.
An entirely different process, called the Swiss method, also soaks the beans in hot water for several hours,
but no methylene chloride is used. Instead the caffeine is removed by filtering the water through activated
charcoal. More or less pure carbon, the molecular structure of activated charcoal has been altered to provide a
large surface area for other molecules to stick to.
The first method is less expensive and so is preferred by most manufacturers. And - no surprise - there are
ongoing debates about whether it degrades the taste. As usual, quality control makes the largest difference.
But, there are even techniques available to the individual for reducing caffeine intake.
Darker, less acidic, roasts already contain less caffeine as a consequence of the roasting process. And blends
of decaf and regular are an option for those who simply must cut down.
As to the taste.... Well, as in any issue of taste, individual preferences generally swamp any objective chemical
differences. Since caffeine has an inherently bitter taste, many can detect its presence or absence. Whether
that makes decaf good or bad is, as they say, a matter of taste.