pH and TA Madness

[jsbeckton]

This is getting pretty frustrating that the numbers look pretty good preferment and then swing wildly during fermentation and MLF.

My Chilean Syrah started on 5/13 has changed as follows:

pH: 3.52 ->3.23
TA: 0.42 -> 0.79

I had a hell of a time reducing acid on my Chilean Merlot from last year so was really hoping not to have to mess with the Syrah this year but that’s a pretty low pH. I used a freshly calibrated Milwaukee pH meter and pretty fresh solutions.
I know that pH and TA changes/adjustments are not an exact science with all of the chemistry going on but does this seem like a pretty big swing?

MLF was completer per paper test and while I am sure it’s not totally degassed it has been vacuum racked a few times.

Thanks for any feedback!

 

[salcoco]

I would at least wait three months or better to attain any meaningful measurements. best of all how does it taste. numbers are not the ultimate measure

 

[jsbeckton]

It’s tart, but I knew the pH when I tasted it so it was a biased taste. It’s in the barrel from now and will stay there for 6-9 months so I won’t be doing anything to it anytime soon.

 

[Rice_Guy]

It is normal for pH to drop and TA increase as the yeast are actively producing CO2 . The numbers wouldn’t look bad at racking off a primary.
At the point where it is bottled it seems that a pH might be 0.2 units above the starting must, haven’t looked at TA enough to guess a trend but logic would suggest TA should drop.

Chilean Syrah started on 5/13 has changed as follows:
pH: 3.52 ->3.23, , , start vs now
TA: 0.42 -> 0.79

CO2 dissolved in water creates carbonic acid, a bitter flavor note, decrease in pH and increase in TA. A less buffered system (salt form of acids) will have more dramatic swings. Earlier this month ran a seltzer water with a 1.000 gravity which was pH 3.5 fresh and 7.2 after the CO2 was removed, TA jumped from .3% to a trace (one drop). A lot of sodas will drop TA by 0.1% by removing the CO2.

The next time you see this, you could degass 45 seconds in a microwave/ 50 ml, cool and rerun to check if this was the effect observed.

 

[billybigcreek]

This is getting pretty frustrating that the numbers look pretty good preferment and then swing wildly during fermentation and MLF.

My Chilean Syrah started on 5/13 has changed as follows:

pH: 3.52 ->3.23
TA: 0.42 -> 0.79

I had a hell of a time reducing acid on my Chilean Merlot from last year so was really hoping not to have to mess with the Syrah this year but that’s a pretty low pH. I used a freshly calibrated Milwaukee pH meter and pretty fresh solutions.
I know that pH and TA changes/adjustments are not an exact science with all of the chemistry going on but does this seem like a pretty big swing?

MLF was completer per paper test and while I am sure it’s not totally degassed it has been vacuum racked a few times.

Thanks for any feedback!

Those numbers actually look good to me. Let it do it’s thing and it will be great.

 

[JohnT]

.42 to .79 is a pretty wild swing (in the wrong direction). I would question your preferment tests.

Not wanting to ask a stupid question, but are you sure of the calibration of your PH meter? how old is your TA kit?

If all that is good, then can I ask if the test sample was strained (clean) on your preferment tests?

 

[jsbeckton]

Good questions, I’m at a loss as well:

• PH meter is Milwaukee MW102 and was calibrated at 2 points (7.01 and 4.01)
• Preferment sample was indeed strained and was also tested about 3 times to help ensure accuracy
• TA kit is only a few months old but also tested a wine from last year and was able to replicate that result so kit seems good.

 

[Johnd]

Good questions, I’m at a loss as well:

• PH meter is Milwaukee MW102 and was calibrated at 2 points (7.01 and 4.01)
• Preferment sample was indeed strained and was also tested about 3 times to help ensure accuracy
• TA kit is only a few months old but also tested a wine from last year and was able to replicate that result so kit seems good.

How was the post ferment sample handled? This is where I’ve had readings go awry. You should do it the same way that preferment samples should be done, just without skins. Take 20-30 ml, warm to mid 70’s, and toss it into a blender, blend 30-40 seconds, it’ll be degassed for sure. Let it settle and strain off a sample. Test results from that sample will be accurate as long as your chems and meter are proper.

 

[jsbeckton]

Post ferment was simply off the pressed skins as the must was already at 70F. I didn’t put in blender or anything.

Today I just tried taking a sample to a rolling boil in the microwave as was suggested above and that didn’t really change anything as the pH was still about 3.23.

 

[stickman]

You already have enough fruit acid to be below a pH of 4, so in this case, dissolved CO2 will only affect the TA test, it will not significantly affect the pH.

 

[zadvocate]

WHAT COULD CAUSE THE TITRATABLE ACIDITY TO INCREASE DURING FERMENTATION?
Winemakers are generally used to observing TA decreases during fermentation due to the precipitation of potassium bitartrate (KHT), which becomes less soluble with increasing ethanol concentration. When the KHT precipitates, it removes a proton from solution that would otherwise have contributed to the TA concentration. Winemakers are generally less used, however, to increases in TA during fermentation.When TA increases are observed, they are almost always associated with red wine ferments. Given it is difficult to obtain a homogeneous sample of red must immediately after crushing, inaccurate must titratable acidity results can sometimes explain TA discrepancies. Analytical error might also explain TA variations in some cases, while errors in tartaric acid additions due to inaccurate weighing might explain the results in others. If analytical error and other factors, such as a high acetic acid concentration can be ruled out, then increases in TA can often be attributed to increased concentrations of succinic acid.

Succinic acid is a normal by-product of alcoholic fermentation and its mean concentration in red and white Australian wines is in the order of 1.2 g/L and 0.6 g/L, respectively. However, concentrations as high as 3.0 g/L have been recorded in red wines for which TA increases have been observed (AWRI publication #817). Yeast strain appears to be an important variable affecting the amount of succinic acid produced. However, a number of other factors might also influence the production of succinic acid, including fermentation temperature, aeration, must clarity and composition (e.g. sugar concentration, nutrient content, pH, titratable acidity, presence of excess SO2), and other environmental factors (AWRI publication #817). It is not currently possible to predict with certainty whether a fermentation will produce a higher than usual amount of succinic acid. However, selection of a known high succinic acid producing yeast strain, used in combination with several of the factors mentioned above, will increase the chance of increased TA.
https://www.awri.com.au/industry_su...uently_asked_questions/acidity_and_ph/#title9