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Help with my CAB TA and pH issues

Hello, I am making my first red wine. I bought 550lbs of CAB from UC Davis's Hopland research station. They said the TA was .62 and that the pH was 3.6 and the brix was 23.2. I picked the grapes about a week after they measured this and when I got them home I found:

TA .52 pH 3.88 Brix 23+ ( I don't have a short range hydrometer I just know it is above 23 and below 23.5)

I don't know why the acid changed so much but we put the grapes in the back of a pickup with a black bedliner. It wasn't very hot but I am wondering if this could make the acid drop and the pH rise?

Anyways I attempted to correct this by adding some tartaric acid. I wanted to bring up the TA to about .7 and hopefully drop the pH. I figured that the 550lbs should yield around 30 gallons of wine so I added 1.8g/L for 118 L for a total addition of 212 grams. I took a sample of juice to my lab and got the following:

TA 9.2 pH 3.7

So I am a little concerned. First off I don't know how the TA got so high with this acid addition. We have a high end pH meter in my lab and yes I calibrated it with fresh standards at pH 4, 7 and 10. Is the acid artificially high since some of the juice is still stuck in grapes that may not have been crushed very well? The total volume of the must is about 53 gallons and even if I messed up my original titration and I go by the previous weeks numbers my acid addition should bring the wine from .62 to .8 which is still in the ideal range for reds. I figured 30 gallons from 550 lbs to be conservative since Lum's book says 13-14lbs of grapes for a gallon of wine even at 15lbs/gal that would be 36 gallons. So can someone explain how they figure the amount of acid to add when you have all those peels in there? None of the books I have really address the issue. I have made a few white wines and since there are no peels in the must I had no trouble adding acid and getting it where I wanted it.

Because of circumstances I went ahead and pitched the yeast. I am not sure I should do any more adjustments and I am hoping the acid will drop to a normal level. Do I add the MLF culture I bought or save it for next years wine? Any advice will be appreciated.

-Alex

Reply to
Alex
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Well everyone can make mistakes, but I measured it more than once because it didn't seem right. I am a 5th year PhD student in biology at Stanford. I make up lots of buffers that require pHing so I do know how to use the pH meter but I wouldn't bet my life on it. I am sure the pH of the sample I took is 3.7 there isn't any room for error unless our standard buffers are bad but that is unlikely. I guess I will take another reading tomorrow and see what it says. I hope you are right about it taking time to reach equilibrium.

-Alex

Reply to
Alex

I'd just leave it alone for now. Unless you're using a Bayanus strain (Prise de Mousse, e.g.) of yeast, add the ML culture when the yeast fermentation takes off.

You'll get better numbers later, after the wine has completed fermentation and has degassed itself. I hope you are planning to age this in a barrel. Cabernets really like barrel aging - preferrably French.

Tom S

Reply to
Tom S

Alex, They are not pressed yet, so if you are sure of you math, and pretty sure of your equipment, I would not worry about it. I did the same thing this year and measured after addition and thought I screwed up big time. (My pH followed the TA though, it was low and the TA was way high.) If the sample was gassy, my pH read high until degassed. If it was not, I dunno... Regards, Joe

Reply to
Joe Sallustio

I took a sample of the wine last night and was going to measure the TA but instead just measured the pH and then drank it. The pH is now reading 3.62. I read somewhere the pH increses durring fermentation so maybe the pH is close to where it should be. I decided to take the advice to sit it out and see what happens.

Reply to
Alex

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