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After a couple days of cold soaking, the
must is inoculated with yeast and fermentation
begins. The carbon dioxide that is produced by
the fermentation pushes skins to the top of the
tank or bin, making a ‘cap’ on top of the liquid.
This cap is kept in contact with liquid as much
as possible because gives the juice color and
tannins. Tannins are the group of chemicals that
naturally exist in the skin and seeds of the
grapes (and many other plants). They give
finished wine varying degrees of astringency.
finished There are two ways that the cap is kept in contact with
the wine: ‘punching down’ and ‘pumping over’. In
the process of punching down, the caps are manually
pushed down into the juice, usually with a pole device.
Historically, people have used their feet for punching
down the cap. For larger quantities of wine, pumping
over is more common: a pump that attached to the
bottom of the tank, and the juice is pumped over to the
top of the cap and circulated this way for 15-20 min.
Either process may be used, but both must be repeated
two to four times a day, until fermentation is complete. two Pressing and Settling
Pressing and Settling
The amount of time that a wine ferments varies
with the type of grape and the method of the
winemaker. In average musts, yeasts convert sugar
into alcohol and carbon dioxide in 10 to 14 days. In
wines that have a higher concentration of sugar,
fermentation can take up to months. Although there is
no definitive test to tell when fermentation is done, the
loss of cloudiness in the must indicates that
fermentation is complete. After fermentation, the
juice (now wine) is pressed away from skins into a
holding tank, where it sits for a few days to allow
sediments and dead yeast cells to settle out. Aging
The wine is put into oak or redwood
barrels for aging. Aging allows oxygen to
enter, and water and alcohol to escape. The
acidity decreases, clarification takes place,
and components of wine form compounds
to enhance flavor and aroma. The wood
also contributes to the flavor. Malo-lactic
fermentation commonly occurs during the
aging of red wines, and contributes to the
mellowing of the...
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This document was uploaded on 03/10/2014 for the course AGRO 1001 at LSU.
- Fall '11