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What Happens When You Brew Coffee
In making coffee, your aim is to extract flavorful solids (including
coffee oils and sucrose and other sugars) from the ground beans without
pulling bitter, astringent tannins along with them. How long you brew the
coffee determines how much solid material you extract and how the coffee
tastes. The longer the brewing time, the greater the amount of solids
extracted. If you brew the coffee long enough to extract more than 30
percent of its solids, you will get bitter compounds along with the
flavorful ones. (These will also develop by letting coffee sit for a long
time after brewing it.)
Ordinarily, drip coffee tastes less bitter than percolator coffee because
the water in a drip coffeemaker goes through the coffee only once, while
the water in the percolator pot is circulated through the coffee several
times. To make strong but not bitter coffee, increase the amount of
coffee—not the brewing time.
How Other Kinds of Processing Affect Coffee
Drying. Soluble coffees (freeze-dried, instant) are made by dehydrating
concentrated brewed coffee. These coffees are often lower in caffeine than
regular ground coffees because caffeine, which dissolves in water, is lost
when the coffee is dehydrated.
Decaffeinating. Decaffeinated coffee is made with beans from which the
caffeine has been extracted, either with an organic solvent (methylene
chloride) or with water. How the coffee is decaffeinated has no effect on
its taste, but many people prefer water-processed decaffeinated coffee
because it is not a chemically treated food. (Methylene chloride is an
animal carcinogen, but the amounts that remain in coffees decaffeinated
with methylene chloride are so small that the FDA does not consider them
hazardous. The carcinogenic organic solvent trichloroethylene [TCE], a
chemical that causes liver cancer in laboratory animals, is no longer used
to decaffeinate coffee.)
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