CONTROLLING OXIDATION IN

YOUR HOMEMADE WINES

- What Exactly Is Oxidation?

If you've ever left the core of an apple sitting out for a couple
of hours, then you've seen oxidation at work. As we all know, the
apple core will turn brown. And, if you've ever been so bold as
to taste an apple after it has turned brown, then you would have
discovered that its flavor has changed as well.

What happens is that oxygen which makes up about 20% of the air
we breath changes the chemical structure of the apple when its
inner part is exposed. This is the same process that turns iron
into rust or causes the pages of an old book to become brown.

When the apple has its protective layer of skin intact, the
oxygen can not get to the proteins and other elements inside the
apple that are subject to rapid oxidation. But once the apple is
bitten into and exposed to the air, it does not take long for a
noticeable amount of oxidation to occur.

No doubt the apple is a dramatic example of oxidation, as
oxidation does not normally occur at such a fast pace with most
fruits. None the less, the effects are the same when oxidation is
given enough time and opportunity.


- How Does Oxidation Effect Wine?

When a wine becomes oxidized it will turn brown - just as the
apple did. White wines will start to show an amber tint and red
wines will start to develop a brown edge when viewed in a glass
that has been tilted. In extreme cases where there is excessive
air exposure over longer periods of time, the wine can develop a
nutty to caramel aroma, and may also develop slight off-flavors
that resemble raisins or cough syrup.

Some wines may develop "bottle sickness". A term used by wineries
to describe a flabby character that can come over a wine when it
is bottled with too much exposure to air. When excessive amounts
of oxygen is thrusted onto a wine in a short period of time, the
wine is effected differently than if it was slowly exposed to air
over longer periods of time.

Bottle sickness is referred to as a "sickness" because the wine
will usually recover if given enough time. Most of the negative
effects caused by bottle sickness are usually reduced
considerably with 2 or 3 months of aging.

It is also important to note that white wines are effected more
easily by oxidation than red wines. This is mainly because red
wines have more color pigmentation than white wines. This extra
color pigmentation acts as an anti-oxidant, preserving the wine's
color and flavor.

Also, it is easier to see discoloration in a white wine than it
is in a red. So as one can conclude, while air exposure must be
given consideration when dealing with any wine, white wines in
particular, must be given special consideration because of their
delicate nature.


-What Can I Do To Reduce Oxidation?

There is no reason to take drastic measures or to become obsessed
with oxidation. The fact that you are reading this article and
are becoming aware of this issue puts you 10 steps ahead of the
unsuspecting home winemaker. By getting into good habits and
taking some rudimentary precaution, you can easily get oxidation
under control.

- Reducing Air Exposure When Siphoning
One of the major sources of oxidation comes from splashing the
wine during siphoning or bottling. Splashing actually invites the
air into the wine. This is much worse than having wine just
simply sit while its surface touches air. Wine can sit for
several days before oxidation will effect the wine to any notice-
able degree.

It is reasonable to say that regardless of how careful you are,
some oxygen will get into the wine during these types of process.
But by carefully filling the container being siphoned into, from
the bottom up you can save the wine from a lot of unnecessary air
exposure.

What is meant by "bottom up"? This means to put the siphon hose
in the very bottom of the container to be filled. So that, as the
wine comes out of the hose it will not be exposed to air, but
rather to the wine that has come out of the hose before it. By
filling the container in this way, only the first bit of wine
coming out of the hose will touch air.


- Reducing Air Exposure When Aging
A second common source of oxidation comes from improper long-term
storage of wine. This long, slow type of oxidation can destroy a
wine's character in a none recoverable way.

While the wine is fermenting, oxidation is not an issue. CO2
gasses from the fermentation help to drive away any notable
amounts of oxygen that may be in the juice itself or in the head
space of the fermentation vessel. So, larger head spaces in
containers during and right after fermentation are not a cause of
oxidation and should be of no real concern.

But, if you plan to bulk age your wine for a few months after the
fermentation has completed, then air contact should be kept to a
minimum. Head spaces in containers need to be reduce by either
moving the wine to a smaller, more appropriately sized container
or topping the wine up with water or another finished wine of
similar style.

It is also important to note here that both light and heat will
speed up the effects of oxidation. That's why it is always
recommended that long term storage of your wine should be done in
a cool, dark area.

Adding a dose of Sodium Bisulfite or Campden Tablets right before
bulk aging or bottling will also help to reduce oxidation. Either
of these will release sulfur into the wine, driving out most of
the oxygen in the wine. It also fills any small head space in the
container with sulfur gases, again reducing air exposure. For
more information about the Sodium Bisulfite or Campden Tablets we
offer, go to:

Sodium Bisulfite & Campden Tablets

It is also recommended that Ascorbic Acid be added to lighter
colored wines at the beginning of fermentation. Ascorbic Acid is
an anti-oxidant that helps to reduce the effects of oxidation.
About 1/8 teaspoon per gallon is sufficient. For more information
about the Ascorbic Acid we offer, go to:

Ascorbic Acid (a.k.a. Anti-Oxidant)

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E. C. Kraus

Home Wine & Beer Making Supplies

Address: 733 S. Northern Blvd. - P. O. Box 7850 - Independence, MO  64053

Phone:(816) 254-7448  Fax:(816) 254-7051  Toll Free: (800) 353-1906

Email: customerservice@eckraus.com

Copyright (c) 2003, Kraus Sales, L. L. C. All rights reserved. This article may be passed

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