Saccharomyces cerevisiae, which has a
greater tolerance for alcohol, but they do
contribute flavor compounds to the finished
wine.
The primary job of the yeast is to convert
sugar to alcohol, but it also produces various
volatile, aromatic molecules that the grape
itself cannot supply. Prominent among them
are the longer-chain alcohols, and esters, a
class of compounds that combine an acid with
an alcohol or phenol. Both yeast and grape
enzymes and the acid conditions also liberate
aromatic molecules from the nonvolatile
sugar complexes in which some are stored in
the grape, so fermentation also brings out the
grape’s own flavor potential.
Temperatures and Times The winemaker
varies the conditions of fermentation
according to the particular kind of wine being
made. In the case of delicate white wines, the
must is fermented for four to six weeks at