Roasting is what converts green beans into what we drink

By MICHAEL HASTINGS
Media General News Service

Green, or unroasted, coffee beans smell and taste nothing like coffee as most people know it.

It's the roasting of the beans that brings out all those wonderful aromas and flavors that have gained coffee such a widespread following.

Two main things happen during roasting. First, water evaporates. Second, a chemical process called pyrolysis breaks down the raw beans' components and forms hundreds of volatile aromatic compounds. These compounds include ketones and aldehydes, which also are responsible for flavors in foods and wine, and sulfides, which are desirable in small quantities but unpleasant, as in rotten eggs, when overabundant.

The optimal release of these compounds is part of the science and art of roasting.

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