All wines are
made in a similar way, with variations
depending on the type to be produced. The
steps are: harvesting, crushing, juice
separation, treatment of the mass of crushed
grapes and juice (called the Most),
fermentation, post fermentation treatment,
clarification, aging, and bottling.
The diversity
and quality of wine results not only from
the kinds of grapes grown but from
distinctive qualities of soil, topography,
and climate. Changes in weather patterns
from one year to the next also have an
influence on the quality of a vintage. In
addition, each vintner or community of wine
makers may have techniques that no one else
knows or uses.
Wine is
ultimately derived from the carbon dioxide
in the air, which penetrates the leaves of
the vine and is converted into starches.
During absorption into the grape the
starches are turned into the sugars fructose
and glucose. During the fermentation process
the sugars are converted into ethyl alcohol
and carbon dioxide. The longer the grapes
are left on the vine, the higher their sugar
content will be.
At the winery
the grapes are crushed and stemmed. Adding
sulfur dioxide or rapidly heating the must
suppresses the growth of wild yeasts and
other organisms that grow naturally in the
vineyard. Depending on the kind of wine, the
juice may be separated from the skins in
order to avoid getting skin pigmentation in
the wine. In red-wine production the skins,
seeds, and juice are all fermented together.
To aid
fermentation, yeast (usually Saccharomyces) is
added to convert the sugars to alcohol. Other yeast strains are used at
different stages of fermentation. Fermentation takes place in large
vats, from which air is excluded to prevent oxidation and discourage the
growth of vinegar-forming bacteria.
Fermentation takes
from ten to 30 days. During the process, temperature control is
necessary to promote yeast growth and to extract the flavors and colors
from the skins (if skins are fermented). A severe change in temperature
can kill the yeast. The best temperature for yeast growth is about 77o F
(25o C). In a vat of fermenting red wine, skins and pulp may float to
the top, forming a cap. This cap can cause heat to build up in the wine
and inhibit color and flavor extraction, problems that can be avoided by
submerging the cap twice daily during fermentation. In large vats the
fermenting must is drawn off at the bottom and pumped back in over the cap.
After fermentation,
the wine is racked (drawn off)
to separate it from the lees--the sediment of largely dead yeast cells. Some wines deposit their sediment
quickly, but other wines remain cloudy
for long periods. The suspended particles must be removed by clarification
in any one of several processes.
Wine is usually aged in wooden containers made of oak or redwood.
The process allows
oxygen to enter and water and alcohol to escape. Acidity decreases,
additional clarification takes place, and the components of the wine
form compounds that enhance flavor and aroma. The wood from the
containers also contributes flavor. The wood-aging process may last many
months or several years, depending on the wine and the quality desired.
Before bottling,
wine may require blending, filtration, and the
addition of an antiseptic
agent to prevent microbe development.
Some wines are aged in bottles
before
being sold. Red wines especially may profit from
two to twenty years of aging.
© Courtesy of Ben
& Linda McCune - HoneyCreek
Vineyard Orchard's
