Winemaking is essentially the art of managing the first (anaerobic)
stage of fermentation to convert grape juice into wine. After
the yeast converts the grape sugars into alcohol and carbon dioxide,
fermentation must be stopped before the wine is converted into
vinegar by the second (aerobic) stage of fermentation.
During the first stage of fermentation, the carbon dioxide which
forms is heavier than air and forms a cap over the wine protecting
it from contact with the oxygen in air and thus preventing the
second stage of fermentation from starting.
As the first stage of fermentation slows, the carbon dioxide
cap begins to dissipate. To protect the new wine it is necessary
to either store it in a sealed container or to cover it with a
blanket of gases. Modern winerys use purified nitrogen, argon
and carbon dioxide to cover wine and prevent oxygen from turning
it into vinegar.
Air is a mixture of nitrogen (78 percent), oxygen (21 percent),
argon (1 percent), carbon dioxide (1/3 of 1 percent), traces of
other gasses such as neon, helium, methane, krypton, nitrogen
oxide, hydrogen, and ozone mixed with varying amounts of moisture
and suspended particulate matter such as dust, spores, and bacteria.
Air is purified and separated into its components by liquification
and fractional distillation.
Wineries use argon and nitrogen because they are both inert
(nobel) gasses and will not combine with wine. Nitrogen
is lighter than oxygen and therefore tends to rise up and allow
any oxygen which may be present to float down and contact the
wine. Argon is heavier than oxygen and if used by itself it tends
to close off the wine completely and can be detrimental. Carbon
dioxide is even heavier than argon, but it is not inert, wine
absorbs carbon dioxide. A minimal level of carbon dioxide is desirable
to give a freshness to wine but an excess amount will result in
a fizzy wine.
Private Preserve is a proprietary mixture of purified nitrogen,
argon and carbon dioxide. Roughly equivalent to the mixture naturally
present in the headspace of a wine bottle, Private Preserve will
not harm the aroma nor the taste of wine.