Total acidity vs pH

[Alan_Rath]

What I’ve learned, so far, is that there is probably a lot of confusion, and a lot of conventional wisdom in how winemakers use these technical details. And that there is probably a wide range of understanding of how useful - or useless - the various numbers can be.

My suspicion is that there are some winemakers who rely on one or more numbers, without great understanding of what they mean. Other winemakers who understand, but don’t rely overly much on them. A few who have a real grasp, and can probably make some sensible use of the numbers. A very few who have years of experience with their own vineyards, and how the numbers correlate with the vintage character. Some who don’t even bother. But no one can take all the numbers, and tell you precisely what a wine is going to taste like

[Ben_M_a_n_d_l_e_r]

What I’ve learned, so far, is that there is probably a lot of confusion, and a lot of conventional wisdom in how winemakers use these technical details. And that there is probably a wide range of understanding of how useful - or useless - the various numbers can be.

My suspicion is that there are some winemakers who rely on one or more numbers, without great understanding of what they mean. Other winemakers who understand, but don’t rely overly much on them. A few who have a real grasp, and can probably make some sensible use of the numbers. A very few who have years of experience with their own vineyards, and how the numbers correlate with the vintage character. Some who don’t even bother. But no one can take all the numbers, and tell you precisely what a wine is going to taste like

Well said.

[Vincent_Fritzsche]

Alan’s post is excellent. Thank you Alan for a clear and entertaining overview of such a complex topic.

I’ll add some more wine-specific analytical chemistry details here, including a couple things that conflict with parts of Alan’s (generally great!) post.

TA = Titratable Acidity
It’s with good reason that the two professionally trained chemists who’ve commented on this post so far both mentioned how irritating/confusing the term “total acidity” is. Let me be very clear here: the term “total acidity” is not used by anyone in the wine industry except as an error/misunderstanding (with a few niche exceptions). Annoyingly, “total” and “titratable” both begin with a “t”, so when we talk about “TA” people understandably get confused. In general, 99% of the time you hear someone say “total acidity” in a wine, they actually mean “titratable acidity”. Yes, this includes on wine labels, in marketing material, and on some supposedly educational websites. “Total acidity” is actually an important concept in the abyssal depths of nerdy wine chemistry but I think it should be separated from this discussion for the sake of clarity.

But what is Titratable Acidity?
Titratable acidity (“TA”) can be thought of as a measure of the “effective acidity” of a wine. First, I will explain what TA is and how we measure it, then we can go on to how this relates to sensory experience and pH.
Remembering from Alan’s post that acids are compounds that can release, or “donate” a proton (a.k.a. hydrogen ion), each acid in wine exists in multiple forms: some of the molecules will have their donatable hydrogen(s) attached, others will not (this is a simplification but the general point is true). The ratio of these forms depends on the pH of the wine, which is determined by the overall chemistry of the mixture……

Greta post Ben (and thanks also, Alan!). I was feeling the need to make the point about titratable acidity (never heard of total acidity in a lab analysis report!) so thanks! We are fortunate in the U.S. that our TAs are shown as tartaric acid equivalents, and the lab analyses also give us pH, of course, but also malic and lactic acid concentrations. This gives wine makers a lot of information (re possible tartaric acid adds (not an issue in my AVA), how your wine’s pH will change if it goes through ML fermentation, the need for cold stabilization in white and rose’ wines, etc.)

I would just add that pH is important to winemakers not just for taste implications, but also when evaluating the microbiology of the wine. ML bacteria for example do poorly in a high-acid, low pH wine matrix (difficult, but not impossible below 3.2; there are many strains and some do better than others). A host of spoilage organisms such as lactic acid bacteria and pediococcus can be pretty much eliminated in wines below 3.4 pH. Brett. is unfortunately more adaptable but nonetheless will usually not flourish as easily. Tech sheets are mostly read by distributors and retail wine buyers. Many (most?) are naturally concerned about stability and they key in on the pH and filtration info (cross flow or other “sterile” filtration thus being common in red wines above 3.4pH, and also for the 90%(?) of white and rose’ wine styles that either have residual sugar, and by the way, are loaded with malic acid and produced without MLF). If you’ve ever experience a bit of fizz on a still wine, it’s probably MLF.

And as Alan noted, the term “total acidity” is typically interchangeable with titratable acidity. Whether that’s simply a malapropism that has endured or something else I couldn’t say.

Also, which lab are you using? Core Enology provides TA, which is Titratable acidity, and also Tartaric and malic amounts in a sample. But I haven’t ever heard of TA being expressed in Tartaric acid equivalents(this would be a challenge because TA contains other acids than just tartaric).

And finally, we have finished malo on Chardonnay under 3.2pH for years. The only limiting factor seems to be total sulfur level. If you use SO2 at the press pan, then it can be a challenge. If you defer using any SO2 until post malo, then the bacteria usually can consume the malic in a similar timeline to the Pinot Noirs.

Interesting. One comment, I routinely finish ml at or below 3.2 and I do use SO2 at the press as I’ve described before, browning the juice and then adding 30ppm to keep the settled juice tight and allow for a productive native ferment. Chemistry from my 2019 Chards before bottling, all post ML:

19 Chardonnay Armstrong Vineyard
TA 6.1g/l
PH 3.16
Alc 11.42%

19 Chardonnay Royer Vineyard
TA 5.7g/l
PH 3.16
Alc 12.4%

19 Chardonnay WV Tardive
TA 6.1 g/L
3.19pH
Alc 12.4%

[Marcus_Goodfellow]

Greta post Ben (and thanks also, Alan!). I was feeling the need to make the point about titratable acidity (never heard of total acidity in a lab analysis report!) so thanks! We are fortunate in the U.S. that our TAs are shown as tartaric acid equivalents, and the lab analyses also give us pH, of course, but also malic and lactic acid concentrations. This gives wine makers a lot of information (re possible tartaric acid adds (not an issue in my AVA), how your wine’s pH will change if it goes through ML fermentation, the need for cold stabilization in white and rose’ wines, etc.)

I would just add that pH is important to winemakers not just for taste implications, but also when evaluating the microbiology of the wine. ML bacteria for example do poorly in a high-acid, low pH wine matrix (difficult, but not impossible below 3.2; there are many strains and some do better than others). A host of spoilage organisms such as lactic acid bacteria and pediococcus can be pretty much eliminated in wines below 3.4 pH. Brett. is unfortunately more adaptable but nonetheless will usually not flourish as easily. Tech sheets are mostly read by distributors and retail wine buyers. Many (most?) are naturally concerned about stability and they key in on the pH and filtration info (cross flow or other “sterile” filtration thus being common in red wines above 3.4pH, and also for the 90%(?) of white and rose’ wine styles that either have residual sugar, and by the way, are loaded with malic acid and produced without MLF). If you’ve ever experience a bit of fizz on a still wine, it’s probably MLF.

And as Alan noted, the term “total acidity” is typically interchangeable with titratable acidity. Whether that’s simply a malapropism that has endured or something else I couldn’t say.

Also, which lab are you using? Core Enology provides TA, which is Titratable acidity, and also Tartaric and malic amounts in a sample. But I haven’t ever heard of TA being expressed in Tartaric acid equivalents(this would be a challenge because TA contains other acids than just tartaric).

And finally, we have finished malo on Chardonnay under 3.2pH for years. The only limiting factor seems to be total sulfur level. If you use SO2 at the press pan, then it can be a challenge. If you defer using any SO2 until post malo, then the bacteria usually can consume the malic in a similar timeline to the Pinot Noirs.

Interesting. One comment, I routinely finish ml at or below 3.2 and I do use SO2 at the press as I’ve described before, browning the juice and then adding 30ppm to keep the settled juice tight and allow for a productive native ferment. Chemistry from my 2019 Chards before bottling, all post ML:

19 Chardonnay Armstrong Vineyard
TA 6.1g/l
PH 3.16
Alc 11.42%

19 Chardonnay Royer Vineyard
TA 5.7g/l
PH 3.16
Alc 12.4%

19 Chardonnay WV Tardive
TA 6.1 g/L
3.19pH
Alc 12.4%

30 ppm total or free?

Though at that level is still typically works fine. I used to add about 30 total ppm. In 2014, we didn’t have an option for cooling all of the juice(massive vintage) and the ambient temps were warm. I had to add and then re-add SO2 to try to prevent ferment before coming off the gross lees to barrel. Everything went through but it took quite a bit of work.

Nice numbers for your 2019s, we’re finished between 3.09-3.16 for finished pH, and abvs between 11.9%(Whistling Ridge) and 12.8% (Temperance Hill).

[Marcus_Goodfellow]

What I’ve learned, so far, is that there is probably a lot of confusion, and a lot of conventional wisdom in how winemakers use these technical details. And that there is probably a wide range of understanding of how useful - or useless - the various numbers can be.

My suspicion is that there are some winemakers who rely on one or more numbers, without great understanding of what they mean. Other winemakers who understand, but don’t rely overly much on them. A few who have a real grasp, and can probably make some sensible use of the numbers. A very few who have years of experience with their own vineyards, and how the numbers correlate with the vintage character. Some who don’t even bother. But no one can take all the numbers, and tell you precisely what a wine is going to taste like

Fortunately, we don’t have to take all the numbers and figure out what a wine will taste like. We can put a sample cup in the ferment and tell you how it will taste. That’s my preferred method. That’s why it’s more
important to have cooks in the cellar than chemists.

But even if a winemaker is any of the permutations you listed above, the vast majority of us work with the same sites from one vintage to the next. Or from sites that are regionally similar.

If there’s a glitch in the understanding, so long as you have the same glitch each year you can develop a process that works. Self referencing work will evolve forward in the face of a bit of ignorance if the ignorance remains the same each year.

Or to put it another way. In the vaccuum of a cellar, it’s not what the numbers mean, it’s what the numbers mean to me.

[Marcus_Goodfellow]

FWIW-I’d love to see how many Berserkers buy a wine based on the tech sheet, and how many buy a based on how the wine tastes…should making it be different?

[Otto_Forsberg]

FWIW-I’d love to see how many Berserkers buy a wine based on the tech sheet, and how many buy a based on how the wine tastes…should making it be different?

Most of the time I can’t taste the wine before buying it, so tech sheets do have a very large impact on whether I’m going to buy a wine or not.

If a wine has no tech sheet, I’m regarding the wine like a wine that has values that are not not to my liking in its tech sheet; in these instances the wine must be either very interesting in some other way or just needs to have reputation good enough for me to make a buying decision.

[Alan_Rath]

FWIW-I’d love to see how many Berserkers buy a wine based on the tech sheet, and how many buy a based on how the wine tastes…should making it be different?

I mostly don’t pay much attention to numbers. A few producers who make larger numbers of wines include that info in their release notes. I’ve always found it interesting to compare those from year to year, and across vineyard sites. But even as a chemist I’ve never felt that I could correlate the numbers with exactly what I’m going to taste in the bottle. I’ll look at abv maybe, but otherwise I trust the producer, look at the character of the vintage from the perspective of temperatures, rain, etc., and rely on my experience over the years with the site.

For me, this discussion has been more about gaining a better understanding of what the numbers mean out of intellectual curiosity, than being able to make a buying decision. I suspect that numbers are more important to really large producers, making hundreds of thousands of cases. Blending, matching what’s in the bottle to consumer expectations year after year, creating stable wine biologically, color, tartrates, etc.

[BenjaminL]

Acid maturity is very important, and wines with higher levels of of malic and lactic tend to perceive as equally acidic, and less pleasant, or with more aggressive acidity, than those with higher levels of tartaric(and typically a lower pH). Also, low pH makes a huge difference in efficacy of Sulfur in the wines for freshness and stability.

Agreed. I worked on Diamond Mountain for a winery that basically picked based on Malic Acid in the grapes (below 0.9 g/L). Grapes metabolize the Malic Acid during extended hang time and the resulting fruit was extremely plush (if we could keep it watered enough). I wouldn’t pick based solely on MA now, but it was an interesting number to watch.

There is an interesting school of thought that we pick grapes based on the extent of our measuring devices: we used to pick on sugar as it is the biggest complement in the grape (~25%), next we picked on TA because we developed titration for the next biggest complement, organic acids (4 - 8%), now we can pick based on something even smaller (Malic Acid anothocyanins, etc, <1%).
It’s definitely an oversimplification but it speaks to technology adoption for the search of what really makes a great wine (hint: it ain’t sugar or acid).

[Marcus_Goodfellow]

FWIW-I’d love to see how many Berserkers buy a wine based on the tech sheet, and how many buy a based on how the wine tastes…should making it be different?

I mostly don’t pay much attention to numbers. A few producers who make larger numbers of wines include that info in their release notes. I’ve always found it interesting to compare those from year to year, and across vineyard sites. But even as a chemist I’ve never felt that I could correlate the numbers with exactly what I’m going to taste in the bottle. I’ll look at abv maybe, but otherwise I trust the producer, look at the character of the vintage from the perspective of temperatures, rain, etc., and rely on my experience over the years with the site.

For me, this discussion has been more about gaining a better understanding of what the numbers mean out of intellectual curiosity, than being able to make a buying decision. I suspect that numbers are more important to really large producers, making hundreds of thousands of cases. Blending, matching what’s in the bottle to consumer expectations year after year, creating stable wine biologically, color, tartrates, etc.

Same here, both for buying wines and this discussion.

Over the years of tasting our wines, and knowing the numbers, the make up of the acids(percentage of tartaric and malic/lactic) seems to have the most discernable affect on flavor. (IMO)

[Chris_Crutchfield]

FWIW-I’d love to see how many Berserkers buy a wine based on the tech sheet, and how many buy a based on how the wine tastes…should making it be different?

I mostly don’t pay much attention to numbers. A few producers who make larger numbers of wines include that info in their release notes. I’ve always found it interesting to compare those from year to year, and across vineyard sites. But even as a chemist I’ve never felt that I could correlate the numbers with exactly what I’m going to taste in the bottle. I’ll look at abv maybe, but otherwise I trust the producer, look at the character of the vintage from the perspective of temperatures, rain, etc., and rely on my experience over the years with the site.

For me, this discussion has been more about gaining a better understanding of what the numbers mean out of intellectual curiosity, than being able to make a buying decision. I suspect that numbers are more important to really large producers, making hundreds of thousands of cases. Blending, matching what’s in the bottle to consumer expectations year after year, creating stable wine biologically, color, tartrates, etc.

Same here, both for buying wines and this discussion.

Over the years of tasting our wines, and knowing the numbers, the make up of the acids(percentage of tartaric and malic/lactic) seems to have the most discernable affect on flavor. (IMO)

Sorry for the dumb question, but given the information posted previously in the thread doesn’t that imply that it does make sense to pay attention to tech sheets and in particular the values of pH and TA? That is, these two values can give you an approximation of the make up of the acids in the wine?

[Alan_Rath]

This masters thesis gives quite a good background for understanding some of the concepts, particularly how and when various acids are formed, and how their concentrations depend on temperature and other factors.

Haggerty_umn_0130M_14244.pdf

My takeaway is that TA on it’s own is only a weakly linked indicator, and you’d need to know the concentrations of individual acids and their salts to even start to make hand waving estimates of how the acidity in a particular wine would influence its overall profile.

But frankly, I’m now further down the path of thinking that what value there is in knowing these numbers is mainly in the hands of a winegrower, in terms of relating a vintage to experience with prior vintages, decisions he might make about farming, picking, vinification. But, maybe except for gross difference in numbers, we consumers are fooling ourselves by thinking we might be able to judge much about any individual wine by looking at numbers. Particularly a wine we have no experience with.

[Ben_M_a_n_d_l_e_r]

My takeaway is that TA on it’s own is only a weakly linked indicator, and you’d need to know the concentrations of individual acids and their salts to even start to make hand waving estimates of how the acidity in a particular wine would influence its overall

This is important. I could show you 100 wines with a TA of 5.6 and just about nothing else in common.

[Alan_Rath]

My takeaway is that TA on it’s own is only a weakly linked indicator, and you’d need to know the concentrations of individual acids and their salts to even start to make hand waving estimates of how the acidity in a particular wine would influence its overall

This is important. I could show you 100 wines with a TA of 5.6 and just about nothing else in common.

Coincidentally, I read a comment just today from William Kelley, about the high Malic acid levels in 2008 Burgundy. Everyone knows that 2008 was a “high acid” year, but I had never heard that correlation, which seems to make a lot of sense. So knowing something about the balance of acids is useful, but just a standalone TA number far less so. Those clues are probably informative in understanding a vintage, as it’s not just the acidity that is unique; other aspects of the grape development and maturity are surely impacted as well by whatever conditions caused the unusually high malic.

[Chris_Crutchfield]

Hmm, I wasn’t suggesting that you only look at TA, but rather the combination of TA and pH. Is it not possible to make generalizations from these values about some characteristics of a wine?

Just like if I see two dry wines of the same varietal, one with 13% ABV and another with 15% ABV. You can’t say with certainty what the styles of these wines are, but you might be able to make some reasonable inferences from these facts.

[Peter_G]

Great thread. My relative experience with this niche of chemistry is practically applied through a long career in biotech/pharma and a short hobby of wine appreciation( ).

From my perspective, pH is a static measure of a wine’s acidity that is noticed in its initial characteristics. The TA is more of a dynamic measure of how long those initial characteristics are maintained.

Another way to consider TA is to think of it as the buffering capacity of the wine. Meaning how much counter ion does it take to move it from the initial pH point to a neutral range. The more counter ion needed to move it, the higher the TA and the longer it takes to move from a lower pH. Conversely, the lower the amount of counter ion needed to titrate from the initial pH to the neutral point, the quicker notes associated with the lower pH are resolved. That’s is buffering capacity.

Lots of great discussion beyond my experience as to why this happens and what contributes to it. How this rolls up to how flavors are perceived and additionally how food can change it are part of what fascinates me about wine.

[Alan_Rath]

I think the buffering capacity of wine is not a good way to think about it. For tartaric acid, everything we’ve learned says you can’t even create a buffered tartaric wine solution, because KHT is so insoluble it will precipitate out the conjugate base side of the buffer.

[Ben_M_a_n_d_l_e_r]

I think buffer capacity is a useful concept to use in wine chemistry but, in general, it is a little too in the weeds for most people. Wines are quite strongly buffered with respect to pH but two wines with the same TA can have quite different buffer capacities. Buffer capacity is an important consideration when making acid adds or deacidifying. My sense is that most winemakers who routinely make acid adjustments have an intuitive and empirical understanding of their wines’ buffer capacities whether they have numbers attached to them or not.

[Ben_M_a_n_d_l_e_r]

My takeaway is that TA on it’s own is only a weakly linked indicator, and you’d need to know the concentrations of individual acids and their salts to even start to make hand waving estimates of how the acidity in a particular wine would influence its overall

This is important. I could show you 100 wines with a TA of 5.6 and just about nothing else in common.

Coincidentally, I read a comment just today from William Kelley, about the high Malic acid levels in 2008 Burgundy. Everyone knows that 2008 was a “high acid” year, but I had never heard that correlation, which seems to make a lot of sense. So knowing something about the balance of acids is useful, but just a standalone TA number far less so. Those clues are probably informative in understanding a vintage, as it’s not just the acidity that is unique; other aspects of the grape development and maturity are surely impacted as well by whatever conditions caused the unusually high malic.

Interesting about 2008 burgundy. I’ve always wanted to do a big analysis of organic acid profiles and vintage character. It’d be messy but there’d probably be something you could pull out of it, and if you focused in on a couple producers and combined it with detailed sensory (yum) you could say something interesting. I bet this has been done at one or more of the very large companies in workshopping the high-volume wines.

[Alan_Rath]

When does buffering come into play in wine? The purpose of a buffered solution is to reduce the impact of some exogenous acid or base addition, and maintain pH in a much narrower range. But wine doesn’t really have a need to be buffered in that sense, does it?