"Nick Cassaro" > wrote in message
...
> The barrel we use is not infected, and for a year the wine is delicious.
> After a year, however, it starts to become vinegar as all wine naturally
> does.

That's not necessarily the case. Wine needs contact with oxygen to turn to
vinegar. It also needs the presence of acetobacter. Once a barrel has
acetobacter in it because the wine in it turned to vinegar that barrel will
try to make vinegar every time you put wine into it. The bacteria gets into
the pores of the wood and it's impossible to get it all out. That barrel is
then only good for making vinegar.

Assuming for a moment that you have a _clean_ barrel, i.e. a new barrel or
one that has no such infection, it is _possible_ to make good wine in it
without the use of preservative (sulfite). It isn't easy though, and it
requires careful attention to details. The barrel has to be kept COMPLETELY
FULL at all times during the aging process, right up to bottling. That
means opening the bung a couple of times a week, replacing the wine that is
lost by evaporation and bunging the barrel _tight_. That's to keep air from
being in prolonged contact with the wine. Acetobacter (and all the other
bugs that try to attack the wine) need air to propagate. Keeping the barrel
plumb full cuts off their air supply. This also applies to the extra wine
you use to top the barrel with. No headspace can be permitted in the
topping wine either. That will require you to use a series of progressively
smaller containers to store the topping wine between uses, so that you can
maintain all of them full too.

If your family is of the custom (as many are) of drawing wine out of a tap
in the head of the barrel over the course of the year, that's your problem.
Whatever you pull out of the tap is being replaced by _airspace_ inside the
barrel, on top of the wine. That space is a playground for spoilage
organisms. At first they grow on the surface of the wine (and on the
surface of the barrel above the wine) and you won't taste their presence at
the tap. Over the course of months the wine from the tap will begin to not
taste so good. Eventually it will have quite a lot of noticeable vinegar
flavor, and at some point it will only be fit to put on your salad! BTW, if
that is representative of your situation, that barrel is only fit for
firewood now.

I was just curious as to which preservatives should be used, how
> much of them, when, etc. etc. to keep at least one bottle from every
> year.

That requires a complicated answer. First off, the preservative you want to
use is sulfur dioxide. It's conveniently available for winemaking as
potassium metabisulfite, which is approximately 50% available sulfur dioxide
(SO2).

Off the top of my head I'd say 50 parts per million free SO2 is what you
should maintain in the wine at all times, from crush to bottling. That's
not as easy as it sounds because when you first add it to the wine some of
it becomes permanently bound to various things in the wine, and is therefore
not available as "free" SO2. If you add 100 parts per million (ppm) at the
crusher, the next day you may measure only 50 ppm free in the must. After
that, however, any more you add will increase the free in a linear fashion.

It gets more complicated. During the course of barrel aging the free SO2
slowly decreases. That's because it's doing its job of scavenging oxygen
from the wine, and in the process it gets used up. Every few months or so
you need to measure the free SO2 and bring it up to where it needs to be to
protect the wine. You shouldn't just arbitrarily dump more in though,
because over sulfiting the wine makes it taste and smell bad, and it may
bleach some of the color out too.

To do it right, you need to know the pH of the wine _and_ the free SO2. The
correct level of free SO2 depends on the pH of the wine. E.g., if the pH
measures 3.20 you need 20 ppm free SO2 to protect the wine. If the pH is
3.40, you need 40 ppm free SO2.

There are inexpensive devices for measuring free SO2. They're called
"Titrets", and you can get them at a homebrew shop. I'd suggest that you
borrow the use of a pH meter rather than investing in one. A local
community college's chemistry department might be willing to help you out
there. Also, I'd recommend that you get a book on home winemaking and read
up on the subject. Jon Iverson's book is pretty thorough, and there are
others as well. Good luck!

Tom S