Where does coffee get its flavor?  Why does it seem to dissipate over time?  What are the things that affect a coffee's flavor?

Coffee does not have any flavor until it is roasted. When it is roasted it undergoes several chemical changes. These changes are what we experience when we taste coffee. As noted in our Superior Roasting Process page, body, acidity, and aroma are the three basic components to the flavor of coffee. Body and acidity are stable, but aroma is variable and dissipates within 2 weeks of roasting!

Roasting creates chemical compounds, gases which we perceive as aroma. Roasting also produces a considerable amount of CO2 (carbon dioxide) in the bean. The beans swell 40-60% during the roasting and much of this interior space is filled with CO2. Over time, as the CO2 leaves, the volatile gases (which create aromas) are carried along, and the new empty space is filled with oxygen. The oxygen reacts with the oils in the beans and turns them rancid. A similar process is responsible for butter or potato chips tasting rancid when left out. This is the reason whole beans in the grocery stores stored in plastic, exposed to the air in non airtight containers, are not fresh and/or taken care of as the gourmet product they could be.

Freeze!

Lowering the temperature of the volatile gases in the beans reduces their rate of dissipation. If you get down below freezing, you reach a point when the gases don't expand at all. This is why coffee stays fresh in the freezer. One of the arguments against freezing is that moisture collects on the beans when they are exposed to warmer air. Since coffee is porous, some of this moisture can be absorbed into the beans.