Different yeast produce different effect on TA

[doughowe]

Hi All,
I recently obtained 15 gallons of frozen syrah. These were thawed, mixed thoroughly together, then split into 2 7.5 gallon batches. Before pitching the pH was ~3.4 and the TA (determined by NaOH titration to pH 8.2) was ~ 0.65. One pail got Lalvin ICV-D21 and the other got Lalvin ICV-D80 yeast. The D21 consistently fermented warmer and more quickly than the D80. Now, at the end of fermentation (D21 has SG 0.994; D80 isn't quite done yet with SG ~1.014), I'm getting pH 3.4 in both batches, but the D21 has TA = 0.78 and the D80 has TA=0.93.

I plan on starting up MLF on these shortly, but I was surprised by the TAs diverging so much. Has anyone else observed this, and or have any comments on what the yeast may be pumping out thats bumping up the TA in the D80 yeast batch compared to the D21 yeast batch?

Thanks for any insights.

Doug

 

[GreginND]

If anything, the TA could drop during fermentation. I don't see how it could go higher. Are you sure your first numbers were accurate? Or, did you thoroughly degas the wine samples before you tested the TA? If there is CO2 present it will produce carbonic acid in equilibrium with the water. That could explain the rise in TA.

 

[Calamity Cellars]

TA is higher from the co2 in solution which takes on the form of carbonic acid. You have to put the sample in a container with a small enough opening to put your thumb over it. Shake then remove your thumb. Repeat until you no longer hear the gas escape as you remove your thumb then test. I'd bet you see that ta drop.


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[doughowe]

Hi Calamity and Greg,
Ah..right! It's been too long since I did TA on recently fermented wine vs. unfermented must. I forgot about the carbonic acid issue. Makes sense since the D21 batch has basically finished primary fermentation and so may have less CO2 in it now, and hence less carbonic acid, than the D80 which is still actively fermenting! I was a bit bummed and surprised with how hight the TA readings were...

In the past I have taken a 15ml sample and microwaved it for 15 seconds to just bring it to a slight boil to drive out the CO2...then immediately cool in a cool water bath to room temp..THEN do the TA analysis. Forgot my own protocol...

I'll post a response here after I test decarbonated samples this weekend. Once I get proper TA and pH readings on decarbonated samples...I may have to reconsider whether the ML step is appropriate for this wine.

Thanks for reminding me (and anyone else who may read this) of this basic issue.

Doug

 

[Calamity Cellars]

Do you need the address to send our consultation checks?


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