Wine Making - Is Ta Or Ph More Important?

[Tim F]

Hey all,

Been wondering about this for a while. I have 'From vines to wines' by Jeff Cox. In it, he emphasises checking and adjusting TA only - "If the TA is just right but the pH is a little high, the smart winemaker would leave it alone." However everything else I've read in books and online and heard from other winemakers is that the pH is more important and this should be adjusted to the right range without regard for TA. Which is right, and why? Or should I just take the TA into account when figuring out which end of the range of ideal pH to get the must into?

For example today our Shiraz had a TA of 0.75 and pH 3.9. What's the best approach here?

 

[Greg.L]

I think a lot of winemakers use pH because it's easier to measure quickly. They are both important, pH is about stability and TA is about flavour, it measures the acids you can taste. TA is important for whites because the acid balance is so important for flavour.

If your shiraz is 3.9 it isn't going to be very stable microbiologically. Spoilage bugs love high pH and SO2 won't be very effective, specially in a red where the pigments bind some SO2. Also the pH will go up a couple of points with fermentation and MLF so you should bring it down to 3.3 or so before fermentation with some tartaric acid. That pH is fairly common with shiraz though the TA seems high. I thought you had a fairly cool season in SA, might have had lower pH? Almost all commercial red wine is adjusted to pH 3.4, I have tested a few bottles and never been wrong.

Greg

 

[pokolbinguy]

Just to add to Gregs comments the reason for dropping the PH down (below 3.56, normally to around 3.3-3.4) is that the SO2 becomes more effective as there is an equilibrium that occurs between the SO2 molecular form and the bisulfite form (the useless type). At the higher PH like yours (3.9) then a high amount will be in the bisulfite form rendering additions fairly useless. This will lead to increases oxidation and much higher instances of microbial spoilage (acetobactor and funky wild yeasts etc).

If you T.A is as low as you suggest, 0.75g/L, I would suggest you re-measure. This is crazy low.

If it was my wine I would add tartaric acid at a rate of around 5g/L. You would be hoping/aiming for a pH around 3.3-3.4 (it will rise a little during MLF so 3.3 will be ok) and a T.A around 6-7g/L expressed.

Hope this helps.

Pok

P.S get your hands on a book by Bryce Rankin called "Making good wine"

 

[Tim F]

Cheers guys!

I think the formula we used gave TA as a percentage, .75% = 7.5g/L - does that sound right? We did the titration a few times, could still be wrong though.

What we did last night was add acid to get to pH 3.6 as we thought that TA was already high. Would it still be worth it at this point to go back and adjust to pH3.4-3.5 as you suggest? It's about 12 hours after crush now.

 

[Greg.L]

3.6 still seems a little high because it will go up during fermentation, you may want to bring it down a little more. it is odd to have such a high TA and pH. I would agree it isn't good to add such big amounts of tartaric, but that is what the big wineries do. You have to balance keeping the TA at reasonable levels against risk of spoilage. Maybe you should do the TA again, its possible to get readings too high if you use tap water.

 

[Tim F]

3.6 still seems a little high because it will go up during fermentation, you may want to bring it down a little more. it is odd to have such a high TA and pH. I would agree it isn't good to add such big amounts of tartaric, but that is what the big wineries do. You have to balance keeping the TA at reasonable levels against risk of spoilage. Maybe you should do the TA again, its possible to get readings too high if you use tap water.

Yeah it did seem strange to me, we did two separate batches of Shiraz this year with similar results. The other one was pH 3.8, TA 6.75g/L. We did the titration a couple of times for each though, using distilled water. I will get a bit more tartaric in there today to get to 3.5 and do another titration when I get a chance!

 

[Greg.L]

At the winery where I used to work in Bathurst, the shiraz always came in at 3.9-4.0. The winemaker never even measured TA, just knocked it straight down to 3.4. When you're dealing with commercial quantities you don't want to take any risks. When I'm making small quantities for myself I try to minimise the use of tartaric, I don't think it helps the flavour. The generally agreed upper limit for safe pH is 3.8.
Remember that MLF will reduce your TA quite a bit, but low pH makes MLF harder.

Greg

 

[pokolbinguy]

The calculation for the titration is "titre measure x 75%" from
Memory. If your titre was 10ml then your answer would then be 7.5g/L