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The beverage called coffee is the result of
mixing dry coffee with water. The combination can be done by one of many
methods - ranging from the very simple, with the minimum of equipment -
to the use of complex coffee machines which can cost thousands of
dollars.
Understanding a few facts about coffee brewing can help answer some of
the questions which arise when wondering which brewing method to use.
A single coffee bean is an extremely
complex entity, being composed of literally hundreds of substances, many
of which are water-soluble. Nearly one-third of these water-soluble
compounds can be removed in normal extraction processes. The goal of
brewing coffee, however, is not to extract the greatest number of
elements from ground coffee, because not all of them are desirable.
Expert tasters generally agree that the
overall coffee flavor, which consists of color, aroma, taste and body,
is best when about 18-22 percent of the flavor components have left the
solid coffee and infused into the water. When more then 22 percent of
the extractable materials permeated into the water, over-extraction
occurs and harsh flavors are added to the brew, as the last substances
to leave the grounds are unpleasant and bitter.
A second technical consideration is
that, even if only the best flavored components have been extracted from
the coffee, the cup flavor can be too concentrated or too diluted,
depending on how much water is used. Again, most expert tasters
generally agree that a cup of coffee tastes best when the liquid
consists of between 98.4 - 98.7 percent water and 1.3 - 1.6 percent
"soluble solids", the latter being what would be left if a cup of liquid
coffee was reduced back to dry ingredients by an evaporation process.
This ideal coffee strength is easily achieved by controlling the
proportion of ground coffee to water, which for European tastes ranges
between 50-75g per 1 liter of water. Many would consider normal strength
coffee as one brewed at about 55g per liter of water. Much of North
America drinks a weaker cup.
The most beautiful and expensive coffee
machines do not always produce the most satisfying cup of coffee, and
when choosing coffee-brewing equipment, consideration must be given to
whether the design allows for a correct balance of brewing factors, as
well as taking into account various safety aspects.
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