AO = Aeration Oxidation ... the process by which you can determine the
levels of free (or total) SO2 in your wine. If you care about
maintaining SO2 at near precise levels, it is a must have.
Alternatively, you can simply err on the high side and maintain a
scheudle of sulfite additions according to the pH.

Essentially, you pull (or push) air through an acidified sample of
wine, then bubbling the released air through an acid-neutralized sample
of H2O2 (hydrogen peroxide) for a defined period of time. Then titrate
that solution to determine the level of SO2. The SO2 is released from
the wine due to acidification and agitation (bubbling). As it passes
through the neutralized H2O2, sulfuric acid is created. By titrating
that, you can determine how much SO2 was released.

Most of the kits are pretty expensive because they use a vacuum pump.
But you can reduce the cost a lot by pushing air rather than vacuum
pumping it. The difference is in the integrity of the tubing and
closures. If you are pushing air through, those tubes, couplings, and
closures have to be perfect - or else you will get a false low reading.
Vacuum pumping is arguably more efficient and less prone to error - but
it costs more. Two years into it, and I'm still fiddling with improving
tube couplings - but my SO2 measurements are plenty accurate enough (as
verified by lab sampling). I use it religiously as I wish to maintain
SO2 at the lowest possible levels - but with enough to keep the wine
from harm.

Truth be told - I have more variance in my pH measurements than I do my
SO2 measurements. I am using a Hanna hand-held meter, now on my second
or third probe, and still find it to be less than stable. I keep it in
storage solution, and perform two-point calibrations prior to use - but
still get variant readings. I am considering investing in a more
expensive table top pH probe.



On 2007-10-30 20:58:17 -0700, Jumbalaya said:

Thanks everyone for the advice.

It's a medium toast French barrel by Tonnellerie Allary (not paraffin
wax lined).

It was a gift although 20L is probably all I can handle as I make on
average 120 liters per year. I wish the barrel had not been drilled
for a spigot though... The first year might be a bit hairy as I
understand 2-3 weeks might be enough time & i would need to rotate the
wines to keep it full.

I have a 54L of Syrah & 54L of Pinot Noir this year, I'm looking
forward to trying this out... I've only previously dealt with oak
chips.

BTW, what's an AO?

Cheers,

Ange