Malolactic finished, pH is way off

[Martin Siebring]

Hi,

I have been part of a wine club that has made wine for many years, this is my first year being the person handling everything. We are making the same blend that we have for several years. 1/3 Cab, 1/3 Merlot, and 1/3 Petite Sirah. All the crushes and presses went fine. I checked the TA and pH of the must before starting the primary fermentations, everything was in a good range. We pressed and then blended. The wine has been going through malolactic the last 3 weeks. The CO2 production has slowed down, so I ran a chromatography test last night. It showed no malic acid and lots of lactic acid, so I think that is done. Tonight I checked the pH and TA to get ready for adding SO2 and racking. TA was 6.4, which seems a little low, but the pH seems way too high at 4.25. The wine also tastes flat. I tasted each variety at pressing, and the acidity seemed about right then on all of them. What do I do now? Is the solution adding tartaric acid to bring the pH down or is there something else I should be doing? Thanks!

 

[NorCal]

What was the pH before ferm & mlf? My Cab went from 3.5 to 3.9, which is a pretty big jump. Do bench trials, but be very careful. You can add very little tartaric in finished wine and make it undrinkable.

 

[salcoco]

bench trials with tartaric acid and taste test is the answer

 

[stickman]

I agree with @NorCal, you're in a tricky spot with the chemistry. You really need to verify those numbers and be sure they are accurate. To me, the TA actually seems a little high for such a high pH. Wine after ML can be nearly saturated with CO2 which can add 2g/l to the TA titration, so be certain to degas the sample before TA testing.

 

[Martin Siebring]

The pH values at crush were 3.6, 3.7 & 3.9 for the 3 varieties. I didn't measure them at press, good learning for next year. I just did taste tests then and I thought everything was great.

I did a bench test last night, I pulled off a gallon and added 1.9g of tartaric acid dissolved in a little warm water and let it sit overnight. This morning, the pH is at 4.2 and TA at 6.4, hardly any movement in the numbers, but the sample tastes much better. Could there be an issue with my tester? I have the Vinmetrica SC-300, and I'm following the directions exactly. I also thought that the TA should be lower for such a high pH reading.

I didn't degas either sample when I tested last night and this morning. I'll do that and test again. I attached the picture of my chromatography test too, maybe somebody can see something wrong there. It's hard to get a decent picture of it.

 

[Martin Siebring]

I just ran tests on degassed samples. The pH didn't register any change, still at 4.2 for both samples. But the TA of the untreated wine measured 5.2, and the TA of my bench trial with the acid addition measured 5.8. Those seem like more realistic numbers based on the pH and my acid addition. So where do I go from here? I can do more bench trials, but I'm nervous about adding much more acid to it, I think my test so far is pretty close to the limit of how much acid I want to add. But with that high a pH, I'm going to have to add a lot of sulfite to get it stable, right?

 

[NorCal]

If it were mine, I'd put away the meter and add Tartaric to taste, then see what the pH was and add sulfites. Is the wine going to be kept in barrel, HDPE or glass? The chart could say add 150-200 ppm, but I would not add any more that 100 the first shot and then try to control the additions to 50, looking to keep total additions below 350 ppm. I would look to bottle and drink early. I've made my share of high pH wines, many of the people I share it with say it is really smooth (vs. flabby); one person's flaw is another's attribute.

 

[stickman]

I also agree, if it were my wine, I would not follow the molecular SO2 graph for high pH red wine. At pH of 3.7 or above, 20 to 30ppm free is recommended throughout aging; (Sulfur Dioxide Basics Revisited March 2012 by Clark Smith). Clark's limit is 3.9 pH for bulk aging, though based on taste you may not be able to get there.

https://www.winesandvines.com/columns/section/92/article/97777/Sulfur-Dioxide-Basics-Revisited

 

[zadvocate]

I apologize if this seems to be a silly question but did you calibrate the pH meter? Also have you thought about trying a different pH meter to verify? That just seems to be rather high given what you’ve said. Otherwise I agree with Norcal. Ad to tase sulfite and go from there. Bench trials like everybody else always says.

 

[StToddy]

in the Inside Winemaking Podcast, Episode 67, Dave Nakaji, winemaker for Sebastiani Vineyards and Winery advises extreme caution with post-ML pH adjustments. He says, at this point "it is what it is" because it is very difficult to make meaningful adjustments without ruining the wine, making it sour and angular. He mentions, after ML he never added more than 0.2 gm/Li.

 

[Martin Siebring]

If it were mine, I'd put away the meter and add Tartaric to taste, then see what the pH was and add sulfites. Is the wine going to be kept in barrel, HDPE or glass? The chart could say add 150-200 ppm, but I would not add any more that 100 the first shot and then try to control the additions to 50, looking to keep total additions below 350 ppm. I would look to bottle and drink early. I've made my share of high pH wines, many of the people I share it with say it is really smooth (vs. flabby); one person's flaw is another's attribute.

I have it stored in HDPE, my plan was to make some teabags with oak cubes as the next step. When you say bottle early, how early? In past years we have barrel aged for close to a year before bottling.

 

[Martin Siebring]

I apologize if this seems to be a silly question but did you calibrate the pH meter? Also have you thought about trying a different pH meter to verify? That just seems to be rather high given what you’ve said. Otherwise I agree with Norcal. Ad to tase sulfite and go from there. Bench trials like everybody else always says.

Not a silly question at all. I calibrate the meter every time before I run a set of tests. I don't have another meter to check it against, and I don't know anybody else around that has one. So I'm kind of stuck on that.

 

[Martin Siebring]

Thank you all for your responses and input so far. The question I came up with this morning is this: Should I hit all the wine with some base level of SO2 to give it some protection and rack it while I figure out what to do about the acid problem? It has only been 3 weeks since I started the MLF.

 

[NorCal]

I have it stored in HDPE, my plan was to make some teabags with oak cubes as the next step. When you say bottle early, how early? In past years we have barrel aged for close to a year before bottling.

I bottle my high pH wine in 10-12 months and drink within three years. My experience is that I lose SO2 2X as fast in a barrel than in glass, and right in the middle of that with HPDE.

Ken