Wine
is an alcoholic beverage made from fermented grape
juice. Wines made from other fruits are always named
accordingly.
There
are many steps in making and producing wine. First,
the grapes must ripen in the vineyard until they
attain suitable sugar content and acidity.
The
next step is fermentation. Crushed grapes are
combined with special wine yeasts that will dominate
over yeast that may have been acquired in the
vineyard (on the grape surface, leaves, and stems)
or in the winery environment (in tanks, barrels,
hoses). The addition of this yeast culture ensures
complete fermentation without the loss of odor
and produces wine with consistent flavor quality.
Followed
by yeast fermentation is a second fermentation
by lactic acid bacteria. This fermentation is
called a malolactic fermentation and during this
process, lactic acid bacteria convert malic acid
to lactic acid and CO2 , which results
in lowered acidity. The bacteria also change the
fruit flavor of wine and add some flavor compounds
from their metabolism.
After
completion of fermentation, wine is filtered and
stabilized. Wine flavors can continue to change
while the wine is stored in wooden barrels, stainless
steel tanks, and in glass bottles. During this
development of wine, various yeasts and bacteria
can be present and further modify wine flavors.
Different wines benefit from longer or only short
aging.
