Can one get an accurate acid reading on must that has begun fermenting?

"james" > wrote in message
om...
> Can one get an accurate acid reading on must that has begun fermenting?

This is an interesting question. Carbon dioxide in fermenting must will
affect your acid titration. And, carbon dioxide in fermenting must will
make it difficult if not impossible to accurately measure your sample. I
suspose one could take a few ounces of fermenting juice and measure the
volume. Then heat the fermenting juice to kill yeast and drive off CO2 that
is present. If the heating evaporates liquid replace it with distilled
water to the starting volume. Then test for acid as usual. One
thing...during fermentation acid content will change. So, the acid reading
you get may not be the starting value.

Bill Frazier
Olathe, Kansas USA

Bill,
Does the acid level always change as the must ferments? Does it
increase or decrease? Do most folks adjust the acid level of their
finished wine according to taste or the acid test after the wine is
finished?
thanks'
James
>
> This is an interesting question. Carbon dioxide in fermenting must will
> affect your acid titration. And, carbon dioxide in fermenting must will
> make it difficult if not impossible to accurately measure your sample. I
> suspose one could take a few ounces of fermenting juice and measure the
> volume. Then heat the fermenting juice to kill yeast and drive off CO2 that
> is present. If the heating evaporates liquid replace it with distilled
> water to the starting volume. Then test for acid as usual. One
> thing...during fermentation acid content will change. So, the acid reading
> you get may not be the starting value.
>
> Bill Frazier
> Olathe, Kansas USA

Bill,
Does the acid level always change as the must ferments? Does it
increase or decrease? Do most folks adjust the acid level of their
finished wine according to taste or the acid test after the wine is
finished?
thanks'
James
>
> This is an interesting question. Carbon dioxide in fermenting must will
> affect your acid titration. And, carbon dioxide in fermenting must will
> make it difficult if not impossible to accurately measure your sample. I
> suspose one could take a few ounces of fermenting juice and measure the
> volume. Then heat the fermenting juice to kill yeast and drive off CO2 that
> is present. If the heating evaporates liquid replace it with distilled
> water to the starting volume. Then test for acid as usual. One
> thing...during fermentation acid content will change. So, the acid reading
> you get may not be the starting value.
>
> Bill Frazier
> Olathe, Kansas USA

james wrote "Does the acid level always change as the must ferments? Does it
increase or decrease? Do most folks adjust the acid level of their finished
wine according to taste or the acid test after the wine is finished?

During fermentation succinic acid increases but this acid is in very low
concentration. Tartaric acid may precipitate out of solution as the
fermentation goes along especially if temperature is cool. Malic acid can
be changed to lactic acid by ML bacteria and this will lower the acid
concentration. But my experience is that acid concentration tends to
decrease over all when fermentation is complete.

Use your taster first to decide if the wine has too much acid. If it's too
tart, depending on the wine, you can add a little sugar. If it's really
acidic tasting do titrations to find out how much acid is in the wine and to
guide you on acid removal. If it's flat tasting do titrations so you know
how much acid can be added without over doing it.

Bill Frazier
Olathe, Kansas USA

james wrote "Does the acid level always change as the must ferments? Does it
increase or decrease? Do most folks adjust the acid level of their finished
wine according to taste or the acid test after the wine is finished?

During fermentation succinic acid increases but this acid is in very low
concentration. Tartaric acid may precipitate out of solution as the
fermentation goes along especially if temperature is cool. Malic acid can
be changed to lactic acid by ML bacteria and this will lower the acid
concentration. But my experience is that acid concentration tends to
decrease over all when fermentation is complete.

Use your taster first to decide if the wine has too much acid. If it's too
tart, depending on the wine, you can add a little sugar. If it's really
acidic tasting do titrations to find out how much acid is in the wine and to
guide you on acid removal. If it's flat tasting do titrations so you know
how much acid can be added without over doing it.

Bill Frazier
Olathe, Kansas USA

james wrote "Does the acid level always change as the must ferments? Does it
increase or decrease? Do most folks adjust the acid level of their finished
wine according to taste or the acid test after the wine is finished?

During fermentation succinic acid increases but this acid is in very low
concentration. Tartaric acid may precipitate out of solution as the
fermentation goes along especially if temperature is cool. Malic acid can
be changed to lactic acid by ML bacteria and this will lower the acid
concentration. But my experience is that acid concentration tends to
decrease over all when fermentation is complete.

Use your taster first to decide if the wine has too much acid. If it's too
tart, depending on the wine, you can add a little sugar. If it's really
acidic tasting do titrations to find out how much acid is in the wine and to
guide you on acid removal. If it's flat tasting do titrations so you know
how much acid can be added without over doing it.

Bill Frazier
Olathe, Kansas USA

If you have a malo-lactic fermentation going at the same time as your
primary fermentation, the total acidity will change as the fermentation
progresses. You can sometimes end up with malo-lactic fermentation occurring
without intending too, since the bacteria responsible can be natrually
occurring. So, while you could get an accurate acid reading for that
particular point in the fermentation, it may not be "accurate" in the sense
of being stable over time.

I don't believe there's anything about the yeast fermentation process itself
that would cause a problem for determining total acidity by titration, or
with determining the pH with a pH meter.

However, if you are titrating and looking for a color change, that will
probably be easier after fermentation has completed and the wine has
cleared. If you're looking to maybe adjust the acidity by beginning a
malo-lactic fermentation, however, you may want to determine the total acid
level prior to the end of yeast fermentation, as the malo-lactic bacteria
like grape skins and other nutrients in the must as well as the heat
generated from the yeast fermentation. You can start the malo-lactic
fermentation later after the yeast fermentation has completed, but you may
want to also add some malo-lactic nutrient to help get it going.


"james" > wrote in message
om...
> Can one get an accurate acid reading on must that has begun fermenting?

If you have a malo-lactic fermentation going at the same time as your
primary fermentation, the total acidity will change as the fermentation
progresses. You can sometimes end up with malo-lactic fermentation occurring
without intending too, since the bacteria responsible can be natrually
occurring. So, while you could get an accurate acid reading for that
particular point in the fermentation, it may not be "accurate" in the sense
of being stable over time.

I don't believe there's anything about the yeast fermentation process itself
that would cause a problem for determining total acidity by titration, or
with determining the pH with a pH meter.

However, if you are titrating and looking for a color change, that will
probably be easier after fermentation has completed and the wine has
cleared. If you're looking to maybe adjust the acidity by beginning a
malo-lactic fermentation, however, you may want to determine the total acid
level prior to the end of yeast fermentation, as the malo-lactic bacteria
like grape skins and other nutrients in the must as well as the heat
generated from the yeast fermentation. You can start the malo-lactic
fermentation later after the yeast fermentation has completed, but you may
want to also add some malo-lactic nutrient to help get it going.


"james" > wrote in message
om...
> Can one get an accurate acid reading on must that has begun fermenting?