19 replies to this topic

[Phil Merrell]

I have a 2011 malbec with a pH of 3.81 and a TA of 6.5g/L . I also have a low free SO2 of 14mg/l that I want to bring up. My plan is to add tartaric acid to lower the pH below 6.5 and then cold stabilize to reduce the acid.''

I also have a 2011 Cabernet with pH of 3.86 and a TA of 5.6. I'm thinking about doing the same adjustment to this wine also.

Any thoughts on this method or the need for adjustment?

Also, I'd like to check my calculations. For the Cab, I want to lower the pH by 0.3. The information I have is 1g/l will reduce pH by 0.1. For the 35 gal. I have the equation is:

1g/L tartaric acid x 0.3pH reduction desired x 132L = 396g of tartaric needed to add
0.1 pH reduction

396g is almost a pound! This seems like a lot of tartaric to add to 35 gal of wine. Does this seem like a lot to you?

Thanks for any help

[saramc]

I know it is early, but this does not make sense to me:
"I have a 2011 malbec with a pH of 3.81 and a TA of 6.5g/L . I also have a low free SO2 of 14mg/l that I want to bring up. My plan is to add tartaric acid to lower the pH below 6.5 and then cold stabilize to reduce the acid.''
Did you mean to lower the pH below 3.5?

Your numbers were correct, here is handy-dandy calculator: http://vinoenology.c.../acid-addition/

And I am assuming these are post-ferment numbers?

[Hugh]

You only need to get to a PH of 3.6, so that when you cold stabalize the PH will go down along with the acid. This allows a smaller addition. That said if your numbers are post MLF I'd wouldn't do it. Many Cabs in the market have similar numbers.

[Brett C.]

I've read repeatedly that the pH tipping point of 3.6 was for acid in water. For wine, it's supposed to be more like 3.9 (Boulton).
I've been running several test on my own high pH, high TA Barbera, and the 1g/l for .1 reduction in pH was close. However, the finished wine was quite high in tartaric and tasted much more tart than it began. So, I've been conducing trials at different acid additions to see what works best. I woudn't risk an entire batch on a formula such as the one mentioned.


Brett

[Crazy Run Ranch]

I don't think I would do anything to the Malbec unless it tastes acidic now. 6.5TA isn't really high. 3.81 pH is high but not impossible. If it tastes good as is, keep it topped and the free SO2 up and you should be fine. The Cab is even higher but that TA is normal to low. I think I would experiment with a bench trial adding small amount of acid and tasting. You might find that .5 gram per liter acid gets your pH down to around 3.8 and your TA would only be 6.1. The main thing is how it tastes not the absolute number. I wouldn't go with the heavy handed approach unless using more subtle tweaks don't work.
Also, don't trust any calculation for reducing pH. The .1 drop per 1 gram acid added is just a guideline. Its better to bench trial with a sample to determine how much you need to add.

[fmestas]

I wouldn't touch either of those wines unless you don't like how they taste. ~3.8 pH is perfectly acceptable for a big, red wine.

[gregorio]

Back away from the acid! Sounds like you are winemaking by numbers. Like others have warned, there is no calculation for PH adjustment. It is all determined through bench trials on each wine. You have not indicated how it tastes.

PH tipping point is 3.65 in the lab but can be a little higher in reality. I have never seen it as high as 3.9 but 3.7 or so is not unheard of. The trouble is, no two wines are alike.

[Phil Merrell]

Thanks everybody. And saramc, I was looking for a pH reduction to 3.5, I was just falling asleep at the keyboard when I posted last night.

Everyone has advised to go slow and with caution, and I will take your advice. I haven't done bench testing before, any advice on batch sizes?

Much Appreciated,

Phil

[gregorio]

Working with liters means the measurments are more accurate. It is easier to measure .1 g in a liter than it is .01 g in 100 ml. Makes extrapolation a snap too.

[glenn1959]

If and when you are going to add acid, don't do it all at once. Do it in stages, recheck, taste then decide

[Phil Merrell]

I did my bench tests and wanted to update everyone on my results. I added 1, 2, and 3 g/L of tartaric to the cabernet and let it sit 24 hrs. After taste testing the results are... (drum roll here), ADD NOTHING wins! I'm still going to rack and up the SO2 to around 25ppm.

Also, I'm going to wait until next weekend and taste the samples again before doing anything. I had to make liter samples since I don't have a scale accurate enough to measure the tartaric for smaller samples, so there's plenty left over. Actually, I had to measure out half a liter of tartaric (I bought a 5lb bag of tartaric - lifetime supply) and weigh it, then do the conversion to teaspoons. Fyi, 1/4 tsp = 1.2 grams.

Thanks again everyone for your wise advice. I'll post the results after next weekends tasting.

[gregorio]

25 ppm at those PH levels is not worth the effort. 50 would be much safer for oxydation but still not offer much safety from bacteria.

[Joe_Sallo]

Maybe I missed something but did you cold stabilize those samples after adding the acid? If you can get them to 25F and give them a bit of agitation you will drop the acid faster. I would bump the SO2 up to 50 PPM like Gregorio said too.

[Crazy Run Ranch]

I added 1, 2, and 3 g/L of tartaric to the cabernet and let it sit 24 hrs. After taste testing the results are... (drum roll here), ADD NOTHING wins!

Not surprising at all, those are huge additions. I was thinking more like .25, .5, .75, 1 grams per liter. Since you have the other high addition samples, might as well cold stabilize and see what happens to acid and pH.

[VitGuy]

I think your numbers look good. Napa Cabs typically have a pH of ~3.8 and a TA of 5-6. If you're going to do a bench trial, the best method is with a liquid solution of 10%. If you make a 10% solution (10g tartaric/100mL of water), then 1 mL of solution per 100 mL of wine sample will be equal to 1 g/L. I would test at 3 rates with a control: .5, 1, 1.5. Then cold stabilize and taste/recheck pH & TA. But, if the wine taste good now, I wouldn't change it. Those are totally exceptable numbers.