Mourvedre question

[AaronSC]

Hi all,
I wanted to seek advice since this is a real outlier for me. I just got a bin of Mourvedre from a reputable vineyard/winery in Amador. It's part of the same harvest they use. The grape hung much longer than pretty much anything else I got this year, and the farmer said he was waiting for the grapes to reach 24 brix to bring in, and the cold had essentially halted ripening (or really slowed it down. They picked yesterday morning because the rains were coming (even started on Monday, though it was clear when the harvest happened).

Now for the confusing part: after a soak overnight I took the brix: 25, so that's completely expected. It always goes up from what the vineyard guys sees in the field. Then I measured the pH: 4.45 ! I tried all sorts of things to remeasure it, recalibrating the pH meter, changing the sensor to a new one and then recalibrating, etc. but it was always very high. Even stranger, one would expect the TA to be very low, right? No, I measured it with the same pH meter and probe that got me 4.45 and the TA was .66.

What do you think is happening here? Could my pH meter be malfunctioning? If so why .66 TA? I emailed the vineyard manager and he said that Mourvedre is a high pH grape (which I knew) and that he would check with the winemaker to see what they got. I am actually not sure what to do, I only see pH that high with really over-ripe grapes and pretty low TAs.

Any thoughts??

Thanks,

-Aaron

 

[Rice_Guy]

pH is critical for food safety, if you would consider a short shelf life like a beer you could get by with a pH above 4, but if it is going to last the pH should be lowered. I would say 3.7 or 3.8 maximum.

 

[NorCal]

I did Mourvedre this year as well, high pH, but I had some high brix to go with it. Your grapes didn’t have a lot of acid and the acid it did have was on the weak side. I’d break out the tartaric and drop it to the 3.7-3.8 as @Rice_Guy suggested.

 

[balatonwine]

Even stranger, one would expect the TA to be very low, right?

Maybe wrong.

A measure of pH is a measure of positively charged H+ ions in solution, on a log scale. While TA is a measure of acid content by weight. They do not have to perfectly correlate. And there can be significant variations.

he was waiting for the grapes to reach 24 brix to bring in

Sadly, this is the old "view" that one can correct for acidity, but adding sugar is forbidden. In fact, is some countries adjusting sugar is against the law for commercial wineries, but they can adjust acidity endlessly. IMHO, that is a silly distinction. To declare one chemical adjustment is "okay" when another is not.....

Better to have harvested when the grapes entered optimal natural ripeness for wine making using the TA brix ratio, or the brix ph^2 method. As well as looking at physical ripeness (stems, seeds, etc). And then harvest when best for the grapes (i.s. not based simply on only one number). Then adjust as desired in the cellar*, using the needed chemicals. If that chemical adjustment was sucrose or tartaric acid, is irrelevant, as they are both simply chemicals.

* However, if harvesting based on multiple cues, holistically, there may be no need for cellar adjustments.

 

[Juniper Hill]

I live in one of the most northern winemaking regions in North America. Adding sugar (chapitalization) is allowed in Nova Scotia, but it's rarely used these days as the grapes are getting plenty ripe with global warming. I'm often still fighting with the acids - too much of it - and have to acid reduce my musts if the pH is less than 3.2 - the yeast don't like fermenting overly acidic must and tend to produce H2S.

For overly alkaline wines - like your Mouvedre, I'd be adding Tartaric Acid. As mentioned above, it will spoil more easily at pH 4.5, and you'll probably notice that the final product won't taste quite right. I'd look at getting the pH down to 3.8.

 

[AaronSC]

Hmmm, well the problem is that I can't simply add tartaric to get to an acceptable pH without radically changing the wine -it would have to be adjusted to around 12 g/l acid. I have made reds with 12g/l (Baco Noir) but that was a fact of nature you have to deal with with Baco in a cool climate, not something I induced.

Right now I'm starting fermentation to see if the high level of particulate might be affecting things. The must is the color of mud (I guess this could probably be due to the high pH) and maybe that's affecting the pH reading. I think I should also redo the TA -a lower TA would be useful here, and my pH meter has been acting weird lately.

If the readings are correct then I do need to add a lot of tartaric or really risk spoilage and accept that the wine be very acidic. I think blending with with a lower acid wine after cold stabilization may be the ultimate answer. I have a several lots of Grenache and Syrah that would be natural.

This grower is likely pretty old school -I was wondering why he was only mentioning brix and never pH. It seems obvious to me that you can't just measure brix and ignore the other factor(s), but that seems to be his way...

-Aaron

 

[balatonwine]

This grower is likely pretty old school -I was wondering why he was only mentioning brix and never pH. It seems obvious to me that you can't just measure brix and ignore the other factor(s), but that seems to be his way...

Even old school vignerons know when to harvest based on physical grape ripeness. Rather this is maybe an example of consumer led thinking regarding the trend toward big, alcoholic reds.

That thinking might work fine most years, but this year is not "normal". In the northern hemisphere, things are not going so great to create that type of wine. And those that are being stubborn, not paying attention to the real world around them, and refusing to be flexible are, IMHO, harvesting sub-optimally. May require a lot of adjustment.

My grapes came in with crazy numbers. But I still paid attention to what the grapes were doing holistically. And harvested based on multiple indicators. And from the cellar so far, the wine is coming off very good. In fact, some of the best wine in the past 5 years. Lemons can make great lemonade, if one pays attention.

And I did not adjust.

 

[stickman]

I haven't experienced a pH of 4.45, that seems very high, I would be very careful to verify the value. If in fact it is that high, dropping the pH may be your only choice to reduce microbial risks, as well as oxidation, loss of color etc. I can't speak for your grapes specifically, but don't overlook the fact that in many cases the added tartaric acid ends up falling out as potassium bitartrate, often the crystals start to drop out near the end of fermentation.

 

[Rice_Guy]

an interesting observation, ,,, with rhubarb or gooseberry or cornelian cherry I haven’t noticed this, ,,, wonder if it is specific to white grapes? where I have seen it , ,

often still fighting with the acids - too much of it - and have to acid reduce my musts if the pH is less than 3.2 - the yeast don't like fermenting overly acidic must and tend to produce H2S.

 

[Juniper Hill]

an interesting observation, ,,, with rhubarb or gooseberry or cornelian cherry I haven’t noticed this, ,,, wonder if it is specific to white grapes? where I have seen it , ,

You might be right. I really have to baby the hybrid whites to get them to ferment clean. Got to the point where I let them ferment in brutes (so I can easily aerate) until last few brix and them transfer to glass. Solid nutrient additions and attention to pH have helped.

 

[bluecrab]

With all that hang time, I wonder if the grapes are a bit dehydrated. My Cab Sav grapes this year were drier than normal at crush. I had to add 2/3 gallon of water per lug of grapes to balance out the must. After pressing, I wound up with the volume of wine I normally get. So, I figure I just replaced the water that was lost from a long hang time. That was luck, not skill. Even if I added a little too much water, though, I think the wine would have been good. After all, people on this forum make good second run wines, so a little extra dilution shouldn't hurt. Anyway, it sounds like the grapes were not picked at the optimal time, so you have to work with what you get.

Here's a thought that maybe others can weigh in on (@Rice_Guy?). If you add distilled water (not acidulated) to your must, you will lower the TA. The pH probably will not change, but you can adjust it down, starting from a lower TA. I say add distilled water, because it has no buffering capacity. If you add a drop of tartaric acid, its pH will drop like a rock. You should do this early in fermentation, so the added water can absorb the goodness from the skins. You'll also want to add sugar, because that will be diluted as well. Your TA will probably drop during fermentation, aging, and cold stabilization, due to acid precipitation. Don't be shy with acid adjustments. Bring it down to pH 3.7, if not lower.

It's just a thought. I'm curious to hear what others think of this.

 

[bluecrab]

Hmmm, well the problem is that I can't simply add tartaric to get to an acceptable pH without radically changing the wine -it would have to be adjusted to around 12 g/l acid. I have made reds with 12g/l (Baco Noir) but that was a fact of nature you have to deal with with Baco in a cool climate, not something I induced.

How did you calculate 12 g/l acid? As pH increases, it takes less acid to reduce it. So, in general, it will take less acid to reduce a must with pH 4.4 by 0.1, than a must with pH 3.8 by 0.1. I do titrations to determine the amount of acid to add. This year, it took about 3 g/l tartaric to bring my wines from pH 4.0 to 3.4. I think you will need less acid than you think to adjust your wine to a good pH.

 

[Rice_Guy]

From a practical point of view we will not see the difference between drinking water and distilled water with a 0.01 accuracy pH meter.
I have been frustrated with buffering capacity (AKA Titratable acidity). The only way I know to find out what the change is is to take 100 grams and titrate with the more acid/ low pH ingredient, example dropping pH of mulberry (malic) by adding lemon juice (citric), ,,, I sometimes cheat and go to the chemical shelf and get the reagent grade phosphoric acid to push the change faster. (In the rice factory phosphoric was “water treatment” so acidified water isn’t on our ingredient label.)
Grape is an interesting crop, ,,, and like all crops it changes year to year, and needs to be rebalanced. I don’t have the experience to reliably predict TA dropping. In looking at finished wines it appears to be the case, as creating esters (acid alcohol complex)

(example with finished wines done this spring looking at how much to back sweeten rhubarb/ malic acid)

Here's a thought that maybe others can weigh in on. If you add distilled water (not acidulated) to your must, you will lower the TA. The pH probably will not change, but you can adjust it down, starting from a lower TA. I say add distilled water, because it has no buffering capacity. If you add a drop of tartaric acid, its pH will drop like a rock. You should do this early in fermentation, so the added water can absorb the goodness from the skins. You'll also want to add sugar, because that will be diluted as well. Your TA will probably drop during fermentation, aging, and cold stabilization, due to acid precipitation. Don't be shy with acid adjustments. Bring it down to pH 3.7, if not lower.

 

[Juniper Hill]

How did you calculate 12 g/l acid? As pH increases, it takes less acid to reduce it. So, in general, it will take less acid to reduce a must with pH 4.4 by 0.1, than a must with pH 3.8 by 0.1. I do titrations to determine the amount of acid to add. This year, it took about 3 g/l tartaric to bring my wines from pH 4.0 to 3.4. I think you will need less acid than you think to adjust your wine to a good pH.

I've used calculations are a ballpark when planning additions. I then purposely undershoot and remeasure. It's kinda like adding salt to soup - you can always add more but it isn't easy to remove.

 

[Nebbiolo020]

How did you calculate 12 g/l acid? As pH increases, it takes less acid to reduce it. So, in general, it will take less acid to reduce a must with pH 4.4 by 0.1, than a must with pH 3.8 by 0.1. I do titrations to determine the amount of acid to add. This year, it took about 3 g/l tartaric to bring my wines from pH 4.0 to 3.4. I think you will need less acid than you think to adjust your wine to a good pH.

earlier this year I had 500 pounds of Syrah split into 3 fermentation vessels I added 500 grams of tartaric split 3 ways and that was 166 grams per each container. This was calculated by my boss at work using the same formula we use for our wines at work.

ph went from 4.12 down to 3.72.

 

[AaronSC]

Update: I ended up adding tartaric in multiple increments, starting with 2g/l. To get the pH to 3.7 it required 4 g/l total. This should have raised the TA to around .9. Strange thing is that in tasting the post-fermentation wine it does not taste acidic at all, in fact less than other wines with lower TAs. Very strange. I have always read that TA had a much bigger impact on perception of acidity than did pH, but this year that has not been my experience. In three different wines that had strange chemistries, the perception of acidity seemed to be a function of pH. Examples: 1) picpoul, which had a fairly low pH of 3.4, but low TA of .54, tasted quite tart (and still does). Normally I would have added acid at .54 for a white, but it doesn't seem like this would be a good idea. 2) Cinsault: grown next to Picpoul, harvested the same day. pH is 3.78, TA is .53, clearly tastes like it is lacking in acid, added tartaric to bring it to .65 and it tastes much better. 3) Mourvèdre, case just discussed, very high pH, moderate TA to start with, perceived acidity at high TA still quite low, higher than usual final pH.

I'm concluding from these limited personal experiences that pH has a much bigger impact on perceived acidity than I have been lead to believe from the literature!?!

 

[cmason1957]

I think what you should conclude is that trying to hit magic numbers for ph and ta is the wrong thing to do. The taste and perception matters more than the "perfect" numbers.