therefore determine many of its qualities.
Their most important components are
Sugars, which the yeasts feed on and
convert into alcohol. Wine grapes are
generally harvested with 20–30% sugar,
mainly glucose and fructose.
Acids, mainly tartaric and some malic,
which help prevent the growth of
undesirable microbes during
fermentation, and are a major component
of wine flavor.
Tannins and related phenolic compounds,
which contribute an astringent feeling
and thereby a body and weightiness to
wine (p. 737).
Pigment molecules that provide color,
and sometimes contribute to astringency
as well. Red grapes contain anthocyanin
pigments (p. 267), mainly in the skins.
“White” grapes lack anthocyanins; their
yellowish color comes from a different
group of phenolic compounds, the