My question concerns how reliable pH testing is, in the setting of an
active fermentation.

Last week, I started with several crates of fresh red grapes. The
initial chemistries were poor...the pH was in the 3.9 to 4.0 range,
and the TA was as low as 0.40. Everytime I "under-adjust", I end up
with flabby though inoffensive wine. This time, I figured that I'd
give it a significant dose of tartaric (about 2.5 g/liter of must). I
plan to cold stabilize as well as do an MLF.

But I'm concerned that I may have overdone it. When I test the pH
now, at the top of the carboy with active fermentation going on, the
pH is in the 3.2 range. I'd like to be in the 3.4-3.5 range.

My question is whether these measurements are accurate. Does the
significant amount of CO2 that's obviously at the top of the carboy
affect pH measurements?

Has anyone had any experience with carbonate additions?

Thanks in advance,

Lee

Lee wrote:

> My question concerns how reliable pH testing is,
> in the setting of an active fermentation.
>
> Last week, I started with several crates of
> fresh red grapes. The initial chemistries were
> poor...the pH was in the 3.9 to 4.0 range,
> and the TA was as low as 0.40. Everytime I
> "under-adjust", I end up
> with flabby though inoffensive wine. This time,
> I figured that I'd
> give it a significant dose of tartaric (about
> 2.5 g/liter of must). I plan to cold stabilize
> as well as do an MLF.
>
> But I'm concerned that I may have overdone it.
> When I test the pH now, at the top of the carboy
> with active fermentation going on, the
> pH is in the 3.2 range. I'd like to be in the
> 3.4-3.5 range.
>
> My question is whether these measurements are
> accurate. Does the significant amount of CO2
> that's obviously at the top of the carboy affect
> pH measurements?
>
> Has anyone had any experience with carbonate
> additions?
>
> Thanks in advance,
>
> Lee

I don't see how the amount of tartaric you added
could have lowered the pH that much. You might
try removing a test size sample of the wine and
allow to set for awhile, recalibrate your pH
meter and re-test.

On Sep 23, 10:26?am, "Paul E. Lehmann" > wrote:
> Lee wrote:
> > My question concerns how reliable pH testing is,
> > in the setting of an active fermentation.
>
> > Last week, I started with several crates of
> > fresh red grapes. The initial chemistries were
> > poor...the pH was in the 3.9 to 4.0 range,
> > and the TA was as low as 0.40. Everytime I
> > "under-adjust", I end up
> > with flabby though inoffensive wine. This time,
> > I figured that I'd
> > give it a significant dose of tartaric (about
> > 2.5 g/liter of must). I plan to cold stabilize
> > as well as do an MLF.
>
> > But I'm concerned that I may have overdone it.
> > When I test the pH now, at the top of the carboy
> > with active fermentation going on, the
> > pH is in the 3.2 range. I'd like to be in the
> > 3.4-3.5 range.
>
> > My question is whether these measurements are
> > accurate. Does the significant amount of CO2
> > that's obviously at the top of the carboy affect
> > pH measurements?
>
> > Has anyone had any experience with carbonate
> > additions?
>
> > Thanks in advance,
>
> > Lee
>
> I don't see how the amount of tartaric you added
> could have lowered the pH that much. You might
> try removing a test size sample of the wine and
> allow to set for awhile, recalibrate your pH
> meter and re-test.- Hide quoted text -
>
> - Show quoted text -

When I first tested the must after adding the acid, it tested
3.38-3.40, which I was happy with. It tasted acidic. But the only
reason I can think of that the pH rose that much was because of all of
the dissolved CO2. I seem to remember that one should heat up a
sample before testing, to drive off the CO2.

On Sep 23, 8:11 am, Lee > wrote:
> On Sep 23, 10:26?am, "Paul E. Lehmann" > wrote:
>
>
>
>
>
> > Lee wrote:
> > > My question concerns how reliable pH testing is,
> > > in the setting of an active fermentation.
>
> > > Last week, I started with several crates of
> > > fresh red grapes. The initial chemistries were
> > > poor...the pH was in the 3.9 to 4.0 range,
> > > and the TA was as low as 0.40. Everytime I
> > > "under-adjust", I end up
> > > with flabby though inoffensive wine. This time,
> > > I figured that I'd
> > > give it a significant dose of tartaric (about
> > > 2.5 g/liter of must). I plan to cold stabilize
> > > as well as do an MLF.
>
> > > But I'm concerned that I may have overdone it.
> > > When I test the pH now, at the top of the carboy
> > > with active fermentation going on, the
> > > pH is in the 3.2 range. I'd like to be in the
> > > 3.4-3.5 range.
>
> > > My question is whether these measurements are
> > > accurate. Does the significant amount of CO2
> > > that's obviously at the top of the carboy affect
> > > pH measurements?
>
> > > Has anyone had any experience with carbonate
> > > additions?
>
> > > Thanks in advance,
>
> > > Lee
>
> > I don't see how the amount of tartaric you added
> > could have lowered the pH that much. You might
> > try removing a test size sample of the wine and
> > allow to set for awhile, recalibrate your pH
> > meter and re-test.- Hide quoted text -
>
> > - Show quoted text -
>
> When I first tested the must after adding the acid, it tested
> 3.38-3.40, which I was happy with. It tasted acidic. But the only
> reason I can think of that the pH rose that much was because of all of
> the dissolved CO2. I seem to remember that one should heat up a
> sample before testing, to drive off the CO2.- Hide quoted text -
>
> - Show quoted text -

This was discussed in the past so you might want to search the archive
for more details. From what I remember, pH should not be affected
(much), TA is. The heat treatment is needed for measuring TA. But you
can always do this and measure the pH as well to take one variable
out.

I agree with Paul that the drop is too big. Normally the pH tends to
go up doing the ferment as potassium from the skins gets extracted
into the juice. So it does seem strange it'd go from 3.4 to 3.2.

Finally, you can't really do much at this point anw, so perhaps the
best option is just to wait, do the ML, naybe cold stabilize and see
where you end up. You can always take out some acid chemically if
necessary but the wine will probably be fine.

We always tend worry a lot about our "babies" when they're taking
their first steps; they're usually turn out just fine on their own...

Pp

On Sep 24, 12:41 pm, pp > wrote:
> On Sep 23, 8:11 am, Lee > wrote:
>
>
>
>
>
> > On Sep 23, 10:26?am, "Paul E. Lehmann" > wrote:
>
> > > Lee wrote:
> > > > My question concerns how reliable pH testing is,
> > > > in the setting of an active fermentation.
>
> > > > Last week, I started with several crates of
> > > > fresh red grapes. The initial chemistries were
> > > > poor...the pH was in the 3.9 to 4.0 range,
> > > > and the TA was as low as 0.40. Everytime I
> > > > "under-adjust", I end up
> > > > with flabby though inoffensive wine. This time,
> > > > I figured that I'd
> > > > give it a significant dose of tartaric (about
> > > > 2.5 g/liter of must). I plan to cold stabilize
> > > > as well as do an MLF.
>
> > > > But I'm concerned that I may have overdone it.
> > > > When I test the pH now, at the top of the carboy
> > > > with active fermentation going on, the
> > > > pH is in the 3.2 range. I'd like to be in the
> > > > 3.4-3.5 range.
>
> > > > My question is whether these measurements are
> > > > accurate. Does the significant amount of CO2
> > > > that's obviously at the top of the carboy affect
> > > > pH measurements?
>
> > > > Has anyone had any experience with carbonate
> > > > additions?
>
> > > > Thanks in advance,
>
> > > > Lee
>
> > > I don't see how the amount of tartaric you added
> > > could have lowered the pH that much. You might
> > > try removing a test size sample of the wine and
> > > allow to set for awhile, recalibrate your pH
> > > meter and re-test.- Hide quoted text -
>
> > > - Show quoted text -
>
> > When I first tested the must after adding the acid, it tested
> > 3.38-3.40, which I was happy with. It tasted acidic. But the only
> > reason I can think of that the pH rose that much was because of all of
> > the dissolved CO2. I seem to remember that one should heat up a
> > sample before testing, to drive off the CO2.- Hide quoted text -
>
> > - Show quoted text -
>
> This was discussed in the past so you might want to search the archive
> for more details. From what I remember, pH should not be affected
> (much), TA is. The heat treatment is needed for measuring TA. But you
> can always do this and measure the pH as well to take one variable
> out.
>
> I agree with Paul that the drop is too big. Normally the pH tends to
> go up doing the ferment as potassium from the skins gets extracted
> into the juice. So it does seem strange it'd go from 3.4 to 3.2.
>
> Finally, you can't really do much at this point anw, so perhaps the
> best option is just to wait, do the ML, naybe cold stabilize and see
> where you end up. You can always take out some acid chemically if
> necessary but the wine will probably be fine.
>
> We always tend worry a lot about our "babies" when they're taking
> their first steps; they're usually turn out just fine on their own...
>
> Pp- Hide quoted text -
>
> - Show quoted text -

Great advice, wait it out is what I would do too.. From what I have
read, pH is not affected by CO2 but that seems silly; I always take 50
ml of sample, bring it to a boil in a microwave, let it cool, add
distilled water to bring the value up to 50 ml again. I need to do
that for TA anyways so just use that sample for pH too. pH can go
down due to fermentation, other acids are formed.

Joe