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Allowing the
yeast access to oxygen at the beginning of fermentation during the
growth phase helps the yeast produce its own lipids. Lipids are an
essential component of the yeast cell membrane, necessary for the
budding and growth of the yeast cells in the early stage of fermentation
and for the protection of the yeast cell from alcohol toxicity in the
latter stage of fermentation. To provide the yeast with oxygen it needs
to multiply (please see the manufacturer's explanation
Lalvin), place only a paper
towel in the neck of the bottles for the first 24 - 48 hrs, until the
must is seen actively "bubbling." Then place airlocks filled
with fresh clean water, on the carboy and gallon jugs for the rest of
the fermentation. The picture on the left illustrates the carboy with
juice 12 hours after the addition of the yeast. The picture on the right
shows the juice in the carboy 48 hrs after the addition of the yeast. An
airlock filled halfway with water is placed on top of the carboy.
The fermentation should occur at 21 C
and will take anywhere from 7 - 12 days in total. Start to monitor the
progress of the fermentation by taking readings with the hydrometer at
day 5. When the specific gravity is below 1000, (i.e. 995), then proceed
with the racking (siphoning). If not, allow the wine to ferment longer
until it reaches a specific gravity below 1000. If the wine takes longer
it is a good idea to gently "swirl" the carboy to move the
viable yeast around the must inside. Remember that the closer the
specific gravity is to 992 the drier the wine will be, because less
residual sugar remains. For example, a wine with an S.G. of 997 will
taste "sweeter" than a wine with an S.G. of 994. |
