Chardonnay
Cold soak last night
I pressed today
23 brix
pH 3.98
TA .32

Add acid to target TA of .7 then recheck pH


Zinfandel
Crushed today
23 brix
pH 4.00
TA .46

Add acid to target TA of .7 then recheck pH


Any other suggestions???


I planned on ML and aging on the lees.
Maybe I will skip the ML this year...

I would approach this the other way around. Add tartaric acid to
bring pH into the 3.5 range then check the TA. pH is much more
important from a microbial stability standpoint, than TA. Excess
tartaric acid can be dropped out when cold stabilizing. The potential
problems of a high pH environment are less easily remedied.

I would not skip the ML on your Zin, again, more for stability than
style. Consider lysozyme if you decide not to ML your Chard.

RD

I have no idea how much Acid to add to lower pH?


RD wrote:
> I would approach this the other way around. Add tartaric acid to
> bring pH into the 3.5 range then check the TA. pH is much more
> important from a microbial stability standpoint, than TA. Excess
> tartaric acid can be dropped out when cold stabilizing. The potential
> problems of a high pH environment are less easily remedied.
>
> I would not skip the ML on your Zin, again, more for stability than
> style. Consider lysozyme if you decide not to ML your Chard.
>
> RD
>
>

It's not easily calculated as pH depends on the buffering capacity of
the juice among other factors. I simply want to point out that TA is
a less important bogey than pH. Add your tartaric acid incrementally,
monitoring pH rather than TA. You may (or may not) need to exceed
your desired TA value of 0.7%, in order to bring the pH down to a
safer level - that's ok it can be dealt with later.

RD

I think I am doing some math wrong.
I need to figure it out.
I added 40 grams of acid which should have gotten me to .7 g/l
But it only took me from .46 g/l to .6 g/l
So I added the same amount again... and did not check it.

I added acid until I was about pH 3.65 or so.
This was twice my calculation to go from .46 to .7

I am going to let it sit over night and recheck the acid and pH



RD wrote:
> It's not easily calculated as pH depends on the buffering capacity of
> the juice among other factors. I simply want to point out that TA is
> a less important bogey than pH. Add your tartaric acid incrementally,
> monitoring pH rather than TA. You may (or may not) need to exceed
> your desired TA value of 0.7%, in order to bring the pH down to a
> safer level - that's ok it can be dealt with later.
>
> RD
>

I guess I should also add..

I did taste the must as I was going, it does taste much better now.




homebrewdude wrote:
> I think I am doing some math wrong.
> I need to figure it out.
> I added 40 grams of acid which should have gotten me to .7 g/l
> But it only took me from .46 g/l to .6 g/l
> So I added the same amount again... and did not check it.
>
> I added acid until I was about pH 3.65 or so.
> This was twice my calculation to go from .46 to .7
>
> I am going to let it sit over night and recheck the acid and pH
>
>
>
> RD wrote:
>> It's not easily calculated as pH depends on the buffering capacity of
>> the juice among other factors. I simply want to point out that TA is
>> a less important bogey than pH. Add your tartaric acid incrementally,
>> monitoring pH rather than TA. You may (or may not) need to exceed
>> your desired TA value of 0.7%, in order to bring the pH down to a
>> safer level - that's ok it can be dealt with later.
>>
>> RD
>>

Some comments -

I agree with RD up to a point. pH is more important from a microbial
stability point of view. The one caveat I would make is that TA is
important for the perceived quality of the wine, especially the
chardonnay. I would recommend doing what RD suggested - increme3ntal
additions of acid and continue to check both pH and TA and taste.

The other comment I'd make is that those are kinda weird numbers. Low
acid, but also low sugar. With those acid readings, I would have
expected a much higher sugar reading. Are you confident in your
testing equipment and procedures?



In article >
> wrote:
> Chardonnay
> Cold soak last night
> I pressed today
> 23 brix
> pH 3.98
> TA .32

> Add acid to target TA of .7 then recheck pH

> Zinfandel
> Crushed today
> 23 brix
> pH 4.00
> TA .46

> Add acid to target TA of .7 then recheck pH

> Any other suggestions???

> I planned on ML and aging on the lees.
> Maybe I will skip the ML this year...

--
I'm using an evaluation license of nemo since 113 days.
You should really try it!
http://www.malcom-mac.com/nemo

I am using a ATC refractometer
I calibrated it with distilled water.

I measured juice direct from berries and after the crush.

I am using a calibrated Hanna Phep5 meter.
I am using Hanna calibration solution.
New probe a week ago.

I am going to take a SG reading with my hydrometer today, to check the
sugar again.

The grapes are from California shipped to the midwest.





AxisOfBeagles wrote:
> Some comments -
>
> I agree with RD up to a point. pH is more important from a microbial
> stability point of view. The one caveat I would make is that TA is
> important for the perceived quality of the wine, especially the
> chardonnay. I would recommend doing what RD suggested - increme3ntal
> additions of acid and continue to check both pH and TA and taste.
>
> The other comment I'd make is that those are kinda weird numbers. Low
> acid, but also low sugar. With those acid readings, I would have
> expected a much higher sugar reading. Are you confident in your
> testing equipment and procedures?
>
>
>
> In article >
> > wrote:
>> Chardonnay
>> Cold soak last night
>> I pressed today
>> 23 brix
>> pH 3.98
>> TA .32
>
>> Add acid to target TA of .7 then recheck pH
>
>> Zinfandel
>> Crushed today
>> 23 brix
>> pH 4.00
>> TA .46
>
>> Add acid to target TA of .7 then recheck pH
>
>> Any other suggestions???
>
>> I planned on ML and aging on the lees.
>> Maybe I will skip the ML this year...
>
>

My Chardonnay sat over night
It is much clearer now, I added yeast last night but there is no
activity yet.

I re-calibrated everything
Brix 24
SG 1.110
pH 4.07
TA .35 g/l


THis is how I worked through my TA
15ml of juice
15ml of distilled water
3 drops of indicator

The was in a beaker placed on a stir plate with pH meter

I added 3.5ml of NaOH then it hit pH 8.22

Based on my math this would be .35 g/l

these new readings are after I added 20 grams of acid last night...
The wine tastes sweet, I still think it is low on acid.

Now I am confused...




homebrewdude wrote:
> Chardonnay
> Cold soak last night
> I pressed today
> 23 brix
> pH 3.98
> TA .32
>
> Add acid to target TA of .7 then recheck pH
>
>
> Zinfandel
> Crushed today
> 23 brix
> pH 4.00
> TA .46
>
> Add acid to target TA of .7 then recheck pH
>
>
> Any other suggestions???
>
>
> I planned on ML and aging on the lees.
> Maybe I will skip the ML this year...

I added 70grams of acid

Now

pH 3.60
TA .65 g/l

10 more grams will bring the TA to .7 g/l

Then I will recheck pH, which should drop more.

I was planning on ML this one, but I guess not now...
I think I will add some oak to the primary



homebrewdude wrote:
> My Chardonnay sat over night
> It is much clearer now, I added yeast last night but there is no
> activity yet.
>
> I re-calibrated everything
> Brix 24
> SG 1.110
> pH 4.07
> TA .35 g/l
>
>
> THis is how I worked through my TA
> 15ml of juice
> 15ml of distilled water
> 3 drops of indicator
>
> The was in a beaker placed on a stir plate with pH meter
>
> I added 3.5ml of NaOH then it hit pH 8.22
>
> Based on my math this would be .35 g/l
>
> these new readings are after I added 20 grams of acid last night...
> The wine tastes sweet, I still think it is low on acid.
>
> Now I am confused...
>
>
>
>
> homebrewdude wrote:
>> Chardonnay
>> Cold soak last night
>> I pressed today
>> 23 brix
>> pH 3.98
>> TA .32
>>
>> Add acid to target TA of .7 then recheck pH
>>
>>
>> Zinfandel
>> Crushed today
>> 23 brix
>> pH 4.00
>> TA .46
>>
>> Add acid to target TA of .7 then recheck pH
>>
>>
>> Any other suggestions???
>>
>>
>> I planned on ML and aging on the lees.
>> Maybe I will skip the ML this year...

I went ahead and added acid to get my TA to .75

My final pH is 3.49



homebrewdude wrote:
> I added 70grams of acid
>
> Now
>
> pH 3.60
> TA .65 g/l
>
> 10 more grams will bring the TA to .7 g/l
>
> Then I will recheck pH, which should drop more.
>
> I was planning on ML this one, but I guess not now...
> I think I will add some oak to the primary
>
>
>
> homebrewdude wrote:
>> My Chardonnay sat over night
>> It is much clearer now, I added yeast last night but there is no
>> activity yet.
>>
>> I re-calibrated everything
>> Brix 24
>> SG 1.110
>> pH 4.07
>> TA .35 g/l
>>
>>
>> THis is how I worked through my TA
>> 15ml of juice
>> 15ml of distilled water
>> 3 drops of indicator
>>
>> The was in a beaker placed on a stir plate with pH meter
>>
>> I added 3.5ml of NaOH then it hit pH 8.22
>>
>> Based on my math this would be .35 g/l
>>
>> these new readings are after I added 20 grams of acid last night...
>> The wine tastes sweet, I still think it is low on acid.
>>
>> Now I am confused...
>>
>>
>>
>>
>> homebrewdude wrote:
>>> Chardonnay
>>> Cold soak last night
>>> I pressed today
>>> 23 brix
>>> pH 3.98
>>> TA .32
>>>
>>> Add acid to target TA of .7 then recheck pH
>>>
>>>
>>> Zinfandel
>>> Crushed today
>>> 23 brix
>>> pH 4.00
>>> TA .46
>>>
>>> Add acid to target TA of .7 then recheck pH
>>>
>>>
>>> Any other suggestions???
>>>
>>>
>>> I planned on ML and aging on the lees.
>>> Maybe I will skip the ML this year...

On Sep 16, 2:12 pm, homebrewdude >
wrote:
> I went ahead and added acid to get my TA to .75
>
> My final pH is 3.49
>
>
>
> homebrewdude wrote:
> > I added 70grams of acid
>
> > Now
>
> > pH 3.60
> > TA .65 g/l
>
> > 10 more grams will bring the TA to .7 g/l
>
> > Then I will recheck pH, which should drop more.
>
> > I was planning on ML this one, but I guess not now...
> > I think I will add some oak to the primary
>
> > homebrewdude wrote:
> >> My Chardonnay sat over night
> >> It is much clearer now, I added yeast last night but there is no
> >> activity yet.
>
> >> I re-calibrated everything
> >> Brix 24
> >> SG 1.110
> >> pH 4.07
> >> TA .35 g/l
>
> >> THis is how I worked through my TA
> >> 15ml of juice
> >> 15ml of distilled water
> >> 3 drops of indicator
>
> >> The was in a beaker placed on a stir plate with pH meter
>
> >> I added 3.5ml of NaOH then it hit pH 8.22
>
> >> Based on my math this would be .35 g/l
>
> >> these new readings are after I added 20 grams of acid last night...
> >> The wine tastes sweet, I still think it is low on acid.
>
> >> Now I am confused...
>
> >> homebrewdude wrote:
> >>> Chardonnay
> >>> Cold soak last night
> >>> I pressed today
> >>> 23 brix
> >>> pH 3.98
> >>> TA .32
>
> >>> Add acid to target TA of .7 then recheck pH
>
> >>> Zinfandel
> >>> Crushed today
> >>> 23 brix
> >>> pH 4.00
> >>> TA .46
>
> >>> Add acid to target TA of .7 then recheck pH
>
> >>> Any other suggestions???
>
> >>> I planned on ML and aging on the lees.
> >>> Maybe I will skip the ML this year...- Hide quoted text -
>
> - Show quoted text -

On reds from grapes I usually try to get the pH to 3.6 and then stop.
I do use tartaric only for that type of addition. I had to add a lot
this year too. My rule of thumb is 4g/gal to increase TA by 1g/l. If
you want to change the pH by 0.1 4g/gal (US) is about right. Bigger
swings than 0.1 PH get a little crazy to calculate. It's easier to
add some acid and just remeasure rather that try to calculate. It's a
logarithmic measurement so you will drive yourself crazy trying to
calculate it out since we think in linear values. Your numbers seemed
a little odd to me too but calibrated is calibrated so go with that.

Joe

What number seems odd?



Your numbers seemed
> a little odd to me too but calibrated is calibrated so go with that.
>
> Joe
>

Think I should still run ML on this zinfadel??

homebrewdude wrote:
> I went ahead and added acid to get my TA to .75
>
> My final pH is 3.49
>
>
>
> homebrewdude wrote:
>> I added 70grams of acid
>>
>> Now
>>
>> pH 3.60
>> TA .65 g/l
>>
>> 10 more grams will bring the TA to .7 g/l
>>
>> Then I will recheck pH, which should drop more.
>>
>> I was planning on ML this one, but I guess not now...
>> I think I will add some oak to the primary
>>
>>
>>
>> homebrewdude wrote:
>>> My Chardonnay sat over night
>>> It is much clearer now, I added yeast last night but there is no
>>> activity yet.
>>>
>>> I re-calibrated everything
>>> Brix 24
>>> SG 1.110
>>> pH 4.07
>>> TA .35 g/l
>>>
>>>
>>> THis is how I worked through my TA
>>> 15ml of juice
>>> 15ml of distilled water
>>> 3 drops of indicator
>>>
>>> The was in a beaker placed on a stir plate with pH meter
>>>
>>> I added 3.5ml of NaOH then it hit pH 8.22
>>>
>>> Based on my math this would be .35 g/l
>>>
>>> these new readings are after I added 20 grams of acid last night...
>>> The wine tastes sweet, I still think it is low on acid.
>>>
>>> Now I am confused...
>>>
>>>
>>>
>>>
>>> homebrewdude wrote:
>>>> Chardonnay
>>>> Cold soak last night
>>>> I pressed today
>>>> 23 brix
>>>> pH 3.98
>>>> TA .32
>>>>
>>>> Add acid to target TA of .7 then recheck pH
>>>>
>>>>
>>>> Zinfandel
>>>> Crushed today
>>>> 23 brix
>>>> pH 4.00
>>>> TA .46
>>>>
>>>> Add acid to target TA of .7 then recheck pH
>>>>
>>>>
>>>> Any other suggestions???
>>>>
>>>>
>>>> I planned on ML and aging on the lees.
>>>> Maybe I will skip the ML this year...

I don't usually do ML on grapes like this, your initial acid numbers
kind of point to overripe but your sugar does not. Overripe grapes
don't have a lot of malic acid as I understand it. People that do
ML routinely usually want to get the target pH a little lower, like
3.3.

Joe

Malolactic conversion will typically reduce acidity. Malic acid, a
dicarboxylic acid, gets decarboxylated to form lactic acid, a
monocarboxylic acid, and CO2(g). This will likely raise the pH
(though not dramically in my hands), not lower it.

Malate, like residual sugar, is a potential energy source for
bacteria. One goal of ML'ing is to remove that potential energy
source. Many species of lactic acid bacteria may be present in a
wine. Some are benign, some are considered spoilage bacteria. Any of
them may eventually utilize the malate under the right conditions
(temp above 65F, pH above 3.2, low sulfite levels, sufficient
nutrients, etc.). It can and does occur after bottling, which can be
heartbreaking after all your effort, leaving you with spoiled wine.
Encouraging the ML conversion by innoculating with a benign strain (O.
oenos) helps me sleep a bit better at night.

To ML or not is entirely up to you. Be sure to maintain adequate SO2
levels for your wine's pH if you choose not to ML.

RD

This is an excellent thread!! I'd like to skew off on a related but
tangent subject if you guys will humor me for a moment...

I recently attended a seminar in which one of the topics was
winemaking techniques for Cynthiana/Norton grapes. These grapes are
typically very high in acid (>1.2) and often high pH (>3.5). The
presenter was advocating the addition of tartaric acid to drop the pH
down to 3.5 prior to fermentation and let the acid fall where it may.
Then cold stabilize after fermentation to precipitate out tartrates
and get the acidity back down. Here's my rub(s):

1. Some resources claim that ML is inhibited in musts with acidity
greater than 1.0. By adding tartaric, the must acidity will exceed
1.2! If these resources are correct, wouldn't the odds of ML inception
and completion be slim? They say ML is particularly important in wine
musts high in malic acid like Cynthiana. What gives?

2. If resources mentioned in #1 above are right, wouldn't acidity in a
pre-fermented wine must be more important than pH to ensure successful
ML? I know pH is very important for long-term stability of wine after
bottling but does it really matter during vinification? Can't wine
stability issues from high pH levels be dealt with after fermentation
simply by adding a little more SO2 prior to bottling?

3. Once the cold stabilization precipitates out the tartaric acid,
wouldn't the must acidity and consequently pH end up right about where
it started before the tartaric addition? If yes, what was the point?

Please enlighted me. I sense I've been missing something crucial in my
winemaking process!

Concerned,
Charles Erwin



On Sat, 15 Sep 2007 18:15:13 -0700, RD >
wrote:

>I would approach this the other way around. Add tartaric acid to
>bring pH into the 3.5 range then check the TA. pH is much more
>important from a microbial stability standpoint, than TA. Excess
>tartaric acid can be dropped out when cold stabilizing. The potential
>problems of a high pH environment are less easily remedied.
>
>I would not skip the ML on your Zin, again, more for stability than
>style. Consider lysozyme if you decide not to ML your Chard.
>
>RD
>

I've included my understanding of your points within your message.

I hope I'm not being too technical to be understood.

Gene

Charles E wrote:
> This is an excellent thread!! I'd like to skew off on a related but
> tangent subject if you guys will humor me for a moment...
>
> I recently attended a seminar in which one of the topics was
> winemaking techniques for Cynthiana/Norton grapes. These grapes are
> typically very high in acid (>1.2) and often high pH (>3.5). The
> presenter was advocating the addition of tartaric acid to drop the pH
> down to 3.5 prior to fermentation and let the acid fall where it may.
> Then cold stabilize after fermentation to precipitate out tartrates
> and get the acidity back down. Here's my rub(s):
>
> 1. Some resources claim that ML is inhibited in musts with acidity
> greater than 1.0. By adding tartaric, the must acidity will exceed
> 1.2! If these resources are correct, wouldn't the odds of ML inception
> and completion be slim? They say ML is particularly important in wine
> musts high in malic acid like Cynthiana. What gives?

I've not heard before about acidity greater than 1.0 inhibits MLF. One
commercial winery I know of occasionally adds 1 gm/liter tartaric acid
without inhibiting MLF. Can you provide a reference that I might read
in which this claim is made?

MLF is inhibited when the pH is lower than 3.1. Adjusting pH downward
to 3.5 is not enough to inhibit ML fermenation.

MLF is inhibited by small additions of fumaric acid, but we don't adjust
pH in our grape must with fumaric acid.

> 2. If resources mentioned in #1 above are right, wouldn't acidity in a
> pre-fermented wine must be more important than pH to ensure successful
> ML? I know pH is very important for long-term stability of wine after
> bottling but does it really matter during vinification? Can't wine
> stability issues from high pH levels be dealt with after fermentation
> simply by adding a little more SO2 prior to bottling?

The yeast's ability for vinification of grapes is not noticeably
affected even at high grape pH. High grape pH does allow some kinds of
bacteria to grow during vinification which can cause off-flavors, so you
have pay more attention to sanitation practices when fermenting high pH
grapes.

At pH greater than 3.8, the chemical form of sulfur which protects the
wine (called molecular sulfur) is in such low concentration that
oxidation and bacterial spoilage of the wine are real risks, unless so
much SO2 is added that you begin to taste it in the wine.

Oxidation and bacterial spoilage is more a problem for white wines than
red wines because the polyphenol compounds in the red wines do offer
some protection.

>
> 3. Once the cold stabilization precipitates out the tartaric acid,
> wouldn't the must acidity and consequently pH end up right about where
> it started before the tartaric addition? If yes, what was the point?

Potassium ions in the grapes are largely responsible for the high pH.
When you lower pH using tartaric acid additions, the tartaric acid
reacts with potassium ions to form potassium bitartrate. Cold
stabilization precipitates (forms crystals) of potassium bitartrate
which do not redissolve in the wine at normal wine storage temperatures.
With the fraction of potassium ions gone from the wine, the pH will stay
lower than where it started.

Other chemical reactions in the wine can raise the pH again, but usually
less than the amount we have lowered it by removing the potassium ions.


>
> Please enlighted me. I sense I've been missing something crucial in my
> winemaking process!
>
> Concerned,
> Charles Erwin
>
>
>
> On Sat, 15 Sep 2007 18:15:13 -0700, RD >
> wrote:
>
>> I would approach this the other way around. Add tartaric acid to
>> bring pH into the 3.5 range then check the TA. pH is much more
>> important from a microbial stability standpoint, than TA. Excess
>> tartaric acid can be dropped out when cold stabilizing. The potential
>> problems of a high pH environment are less easily remedied.
>>
>> I would not skip the ML on your Zin, again, more for stability than
>> style. Consider lysozyme if you decide not to ML your Chard.
>>
>> RD
>>
>

Charles,
I've not heard anything about high TA being an issue with ML either
but most of the books I read don't talk a lot about hybrid
winemaking. I have a few that do so I'll look. I'm hoping to make a
few hybrids this year and it's always good to brush up. I'm sure the
people at Cornell have thoughts on this and most of their work is not
to hard to find on the internet. An email to them always gets
answered also.

Did the mention using Lalvin 71B? It likes malic acid and often
consumes a bit of it during fermentation.

RD,
I probably could have phrased that previous post better; I was not
saying ML will lower pH. I was saying shooting for a pH of 3.5 might
not add enough tartaric to bring the potassium out. It's my
understanding that high TA and high pH usually indicates a high
potassium level. Genes post was much clearer on that. Tom S always
shoots for 3.3 as I remember it.

Joe

Hi Joe, Thanks for the clarification. I see what you meant now about
high TA/ high pH/ and K+.

RD

They are about done fermenting
I have racked the Chardonnay because it had a slight sulfur smell.
I will press the Zin shortly

My new numbers.

Chardonnay
SG 0.995
pH 3.45
TA 0.68


Zinfandel
SG 1.005
pH 3.6
TA 0.77

I added ML and nutrient to the Zin today

Thanks for clearing this up for me Gene, Joe, and RD. The resource I
was referring to was Home Winemaking by Iverson. After reading your
responses, I reconsulted the book and found I took a statement out of
context about high acid and ML and missing the real point of the
chapter on raising acidity. After more careful reading, Iverson is
consistent with your comments. How could I have missed such a
fundamental and critical point!?! That does explain why one of my high
pH wines I made in the past ended up with slight off aromas even
though I was careful to keep the SO2 levels consistent with the chart
recommendations AFTER fermentation.

Thanks again for your advice guys! It is much appreciated by this
novice winemaker...

Charles


On Thu, 20 Sep 2007 13:27:17 GMT, gene > wrote:

>I've included my understanding of your points within your message.
>
>I hope I'm not being too technical to be understood.
>
>Gene
>
>Charles E wrote:
>> This is an excellent thread!! I'd like to skew off on a related but
>> tangent subject if you guys will humor me for a moment...
>>
>> I recently attended a seminar in which one of the topics was
>> winemaking techniques for Cynthiana/Norton grapes. These grapes are
>> typically very high in acid (>1.2) and often high pH (>3.5). The
>> presenter was advocating the addition of tartaric acid to drop the pH
>> down to 3.5 prior to fermentation and let the acid fall where it may.
>> Then cold stabilize after fermentation to precipitate out tartrates
>> and get the acidity back down. Here's my rub(s):
>>
>> 1. Some resources claim that ML is inhibited in musts with acidity
>> greater than 1.0. By adding tartaric, the must acidity will exceed
>> 1.2! If these resources are correct, wouldn't the odds of ML inception
>> and completion be slim? They say ML is particularly important in wine
>> musts high in malic acid like Cynthiana. What gives?
>
>I've not heard before about acidity greater than 1.0 inhibits MLF. One
>commercial winery I know of occasionally adds 1 gm/liter tartaric acid
>without inhibiting MLF. Can you provide a reference that I might read
>in which this claim is made?
>
>MLF is inhibited when the pH is lower than 3.1. Adjusting pH downward
>to 3.5 is not enough to inhibit ML fermenation.
>
>MLF is inhibited by small additions of fumaric acid, but we don't adjust
>pH in our grape must with fumaric acid.
>
>> 2. If resources mentioned in #1 above are right, wouldn't acidity in a
>> pre-fermented wine must be more important than pH to ensure successful
>> ML? I know pH is very important for long-term stability of wine after
>> bottling but does it really matter during vinification? Can't wine
>> stability issues from high pH levels be dealt with after fermentation
>> simply by adding a little more SO2 prior to bottling?
>
>The yeast's ability for vinification of grapes is not noticeably
>affected even at high grape pH. High grape pH does allow some kinds of
>bacteria to grow during vinification which can cause off-flavors, so you
>have pay more attention to sanitation practices when fermenting high pH
>grapes.
>
>At pH greater than 3.8, the chemical form of sulfur which protects the
>wine (called molecular sulfur) is in such low concentration that
>oxidation and bacterial spoilage of the wine are real risks, unless so
>much SO2 is added that you begin to taste it in the wine.
>
>Oxidation and bacterial spoilage is more a problem for white wines than
>red wines because the polyphenol compounds in the red wines do offer
>some protection.
>
>>
>> 3. Once the cold stabilization precipitates out the tartaric acid,
>> wouldn't the must acidity and consequently pH end up right about where
>> it started before the tartaric addition? If yes, what was the point?
>
>Potassium ions in the grapes are largely responsible for the high pH.
>When you lower pH using tartaric acid additions, the tartaric acid
>reacts with potassium ions to form potassium bitartrate. Cold
>stabilization precipitates (forms crystals) of potassium bitartrate
>which do not redissolve in the wine at normal wine storage temperatures.
>With the fraction of potassium ions gone from the wine, the pH will stay
>lower than where it started.
>
>Other chemical reactions in the wine can raise the pH again, but usually
>less than the amount we have lowered it by removing the potassium ions.
>
>
>>
>> Please enlighted me. I sense I've been missing something crucial in my
>> winemaking process!
>>
>> Concerned,
>> Charles Erwin