THERE'S VINEGAR IN MY WINE!

There's something about the wine you're drinking that may
surprise you. There's vinegar in it.

It doesn't matter if you made the wine using fruits from your own
backyard or from pre-packaged juices like we offer. It doesn't
even matter if you made the wine yourself or picked up a bottle
from the local liquor store. There's vinegar in it.

In fact, vinegar is an integral part of wine. That is to say if a
wine contained absolutely *zero* vinegar it would taste less
eventful, lacking of character and out of balance. There have
even been some wineries that have been known to encourage a
minimal amount of vinegar production to enhance the character of
their wine in a controlled and subtle way.

This may all sound absolutely weird to you, but the fact is that
the natural process of making wine lends itself the production of
some vinegar. There's simply no way around it. Here's why...


-- Why Is Vinegar In Wine?

Vinegar is the result of a process. Much like sugar is converted
into alcohol during a fermentation, alcohol can be converted on
into vinegar. Veteran winemakers refer to this vinegar as "acetic
acid"--one of the many types of "volatile acids" that can occur
in a wine.

Much of the vinegar that may be in a wine is produced by a
bacteria known as acetobacter. This microorganism is naturally
everywhere: on the skin of the grape; floating in the air; on
your wine making equipment. This acetobacter consumes the alcohol
and creates acetic acid (vinegar).

But what many home winemakers do not realize is that vinegar is
also produced by the yeast as well. That's right. The yeast also
takes a fraction of the sugars available to them and reduce them
on down to acetic acid during fermentation. So, if your goal is
to make a wine that is *vinegar free*, your efforts will be
ultimately futile.


-- What's The Point Of Telling You This?

The point to all of this is to help you understand that vinegar
plays a definite and acceptable role in the make-up of any wine,
whether it be a Grenache Rose from the local liquor store or
blackberry wine from your own backyard. It is not something to be
feared but rather something to be understood and managed.

Your role in all of this, as a winemaker, is to limit the
production of vinegar. Keep it to a reasonable level, one that is
in harmony with the wine. If the acetobacter is left to its own
natural coarse, then yes, you will eventually end up with a batch
of full-fledge vinegar ready for your next salad. But, with a
little bit of understanding you can limit the vinegar production
to a reasonable amount with minimal effort.


-- Putting Vinegar In Perspective.

The production of vinegar and other volatile acids in a wine is
considered undetectable at levels of .05% or less by volume. And,
it is considered acceptable in concentrations as high as .10% by
volume. California, for example, has put limits on volatile acid
volume at .10% for whites and .12% for reds. Australian wines are
allowed to have up to .15% by volume.

Domesticated wine yeast will produce volatile acids--mostly
vinegar--in the range of .02% to .06%, depending on the
conditions of the fermentation. Warmer, faster fermentations tend
to produce more volatile acids than cooler, slower fermentations.
Wild yeasts will produce much higher levels of volatile acid.

The vinegar is usually noticeable as an odor coming from the wine
before it is noticeable as a flavor within the wine. The odor is
what one could described as fingernail polish.

Many novice winemakers mistake the flavors and bouquet of a dry
wine as being that of vinegar. One must be careful when assuming
their wine is turning to vinegar. Quite often it is only a case
of the winemaker not liking drier wines. This type of problem can
easily be solved by making a final adjustment to the sweetness of
the wine and then adding a wine stabilizer to prevent the
occurrence of re-fermentation.


-- How To Control Vinegar Production

There's not much you can do to control vinegar production during
fermentation other than to keep the fermentation temperature
below 75 degrees F., as mentioned earlier. Doing so will keep the
volatile acid production done by the yeast well below acceptable
levels.

It is acetobacter that we must primarily concern ourselves with
when we talk about controlling the volatile acids in a wine.
During the fermentation the acetobacter is not able to produce
vinegar to any relevant degree. This is because of the inhibiting
effects CO2 gas has on acetobacter--assuming you have a vigorous,
healthy fermentation. But, once the fermentation has ended and
the protective CO2 gases are no longer being produced, it is then
time for measures to be taken that will help to control the
acetobacter.

It is important to understand that the production of vinegar is
an oxidative process. In other words it takes oxygen to produce
vinegar. Without oxygen the acetobacter poses little threat. So,
the key to keeping vinegar production to an acceptable level is
to keep the oxygen away from, and out of, the wine. There are two
basic ways of accomplishing this task:

1. The first way to reduce the oxygen made available to the
acetobacter is to store the wine in a container that has next to
no head-space.

During the fermentation the head-space is of little consequence.
Even fairly large head-spaces are of little issue while an active
fermentation is present. This is because the head-space is being
filled with protective CO2 gas from the fermentation during this
time, but after the fermentation has completed and the container
has been opened and exposed, then head-space does become an
issue.

After the fermentation has completed you will want to either move
the wine to a more appropriate-sized container that will provide
little head-space or you will want to top-up the container that
the wine is currently in. For more information about how to go
about topping up a container, see the following article listed on
our web site:

"Topping Up Your Wines"

2. The second way to reduce the amount of oxygen that is
available to the acetobacter is to use sulfites. This would be
items such as: Campden Tablets, Sodium Bisulfite and Potassium
Bisulfite. Any of these items will be effective in not only
controlling the amount of oxygen available to the acetobacter,
but they are also effective in destroying the bulk of its
existence.

It is important to note here that you should not use sulfites
during a fermentation as this will interfere with the performance
of the yeast just like it does the acetobacter.

For more information about the sulfites we offer, go to the
following link on our web site:

Purifiers & Preservatives


-- Fixed Acids Vs. Volatile Acids

There are two major categories of acids in a wine: "fixed acids"
and "volatile acids".

Fixed acids are acids such as citric acid, tartaric acid or malic
acid. All three make up Acid Blend, commonly used in wine
recipes. Other examples of fixed acids would be the tannic acid
found in Wine Tannin; or, the Ascorbic Acid used in some wines to
preserve flavor and color.

These acids are called fixed acids because they are stable within
the wine when stored under normal conditions. As the wine sits
the level of these acids do not change. They are "fixed."

On the other hand, volatile acids such as vinegar are not stable.
If a wine sits open at normal temperatures, vinegar along with
other volatile acids will slowly dissipate from the wine. And, at
warmer temperatures they can dissipate fairly rapidly. This is
one of the reasons that vinegar effects the bouquet of a wine so
easily. What you are smelling is the vinegar as it slowly
dissipates from the wine.

It is this difference between fixed acids and volatile acids that
allows the home winemaker to do their own test for volatile
acidity in their homemade wines.


-- How To Test For Vinegar In Your Wine

Professional wineries will test the volatile acidity (vinegar) by
distilling it off of the wine to obtain a measurement. This
method is fairly accurate but hardly practical for the home
winemaker.

But, there is another method that is much easier to perform,
however it is not quite as accurate. Having said this, it is
accurate enough for the average home winemaker's needs. It
involves comparing two acid level readings taken with an Acid
Test Kit.

For more information about the acid test kit we offer see the
following link on our web site:

Acid Test Kit

The Acid Test Kit will give you the percentage of acid in a given
wine by volume. For example, a typical reading might be .65%.
This percentage includes both fixed and volatile acids.

If one were to boil the volatile acids off of the wine and take
another reading, they might get .60%, or maybe .55%, depending on
how much volatile acid was in the wine. By comparing the second
reading with the first then you can determine the level of
volatile acids (mostly vinegar) that is in your wine.

To take the above example further, in the case of a second
reading being .60% this would means that your wine has a volatile
acid level of .05% (.65% less .60%). If you ended up with a
reading of .55% then in this example your wine would have a
volatile acid level of .10% (.65% less .55%).

The boiling process needs to be done with some care. First, the
sample of wine you use should be accurately measured. Starting
with an even pint or cup as a sample is reasonable depending on
the size of sauce pan you have available.

Boil the wine until it is roughly 1/3 its original volume. Add
boiling water--distilled preferably--to the wine to bring it back
close to its original volume. And, then allow it to boil down to
1/3 its original volume, again. Repeat this process for a third
time.

Once you have completed the boiling process and the sample has
had time to cool to room temperature, it may be necessary to do a
final adjustment with more distilled water before taking your
second reading. It is very important that the sample ends up
being the exact same volume as when you started. Remember,
accuracy is important here.

The last step is to take your second reading with the Acid Test
Kit and compare that reading with the one you took of the sample
of wine that was not boiled, and you are done.

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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) 2004, Kraus Sales, L. L. C. All rights reserved. This article may be passed

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