On Food and Cooking

The Development of Coffee Flavor The hotter
the bean is roasted, the darker it gets, and its
color is a good indicator of flavor balance. In
the early stages of roasting, sugars are broken
down into various acids (formic, acetic,
lactic), which together with their own organic
acids (citric, malic) give light-brown beans a
pronounced tartness. As roasting proceeds,
both the acids and astringent phenolic
materials (chlorogenic acid) are destroyed, so
acidity and astringency decline. However,
bitterness increases because some of the
browning-reaction products are bitter. And as
the bean’s color becomes darker than medium
brown, the distinctive aromas characteristic of
prized beans become overwhelmed by more
generic roasted flavors — or, conversely, the
flavor deficiencies of second-rate beans
become less obvious. Finally, as acids and
tannins and soluble carbohydrates decline
with dark roasting, so does the brew’s fullness
of body: there’s less there to stimulate our