TA and pH

I would give you my input but it is apparent that no one here cares about factual information.

couldnt help it.

TA (Total Acidity) is a measurement of acid in wine. PH is a measurement of the strength of the acid (not quantity). The two are not linear.

Salut/Hi Vino,

le/on Sat, 17 Apr 2004 04:42:12 GMT, tu disais/you said:-

Not quite as obvious as that.

This is somewhat technical, Vino, but given that Vincent seemed to be treating them as if they were wildly different, I think it might be worth explaining a bit.

Total acidity is (as I understand it) the sum of the weights of the various acids (malic, lactic, citric, tartaric (especially)) present in a litre of wine. I'm not sure how it's calculated, (whether by titration, for example, or by estimation from pH) or how it's expressed - I warned you this was technical, but one MAY take the view that it is most useful to express total acidity as IF all the acids were Tartaric, because that's the predominant acid present so you titrate the acids and then work out what that would give in grams/litre of Tartaric acid.

As for pH, this is a measure - quite simply - of the proportion of Hydrogen ions in the solution. Some acids dissociate more than others, so they taste more acid and have a lower pH than others. In winemaking a common example is of malic and lactic acids. Malic acid is a "stronger" acid than Lactic, as it is more dissociated, it tastes sourer and has (in equal gram molecular strengths) a lower pH. However if one were measuring JUST the acidity in grams, you might have MORE lactic acid, therefore a higher TA, but end up with a wine that was less sour, due to the fact that lactic acid is a weaker acid. OK?

Well, when wine undergoes malo-lactic "fermentation", the malic acid is converted to lactic (I've absolutely NO idea of their valency or chemical formulae, btw) and the pH drops, as you know. However, there's no reason to expect the total acidity to change much, IF this is a real measure of the weight acids present.

So pH is a measure of how highly acid the wine behaves, and sour it tastes (which CAN be masked by lots of sugar, obviously). Total acidity is a matter of simple weights, but doesn't necessarily relate to the freshness of the wine. It would, if all the acid was always Tartaric, of course.

More insults Ian? "wildly different"? What the heck are you talking about. anything to make me look wrong while you said just about the same thing I did with more words. You are slime.

Hi, Ian - I can elaborate a little on this topic. TA (titrable acidity) is measured by titrating a known volume of a degassed (to remove error from dissolved CO2) sample of wine against a standard NaOH solution, using either phenolphthalein for an indicator or while observing the pH with a meter. The result is expressed as though it were all tartaric acid in the sample. IIRC, the Europeans express TA as sulfuric - which gives a number that differs by a scalar.

Right concept, but ML causes the pH to _rise_; the TA drops.

Malic acid is diprotic, meaning it has two active hydrogens. The conversion to lactic acid (which is a monoprotic acid) is a decarboxylation of malic acid by leuconostoc oenos (or similar strain) of bacteria, releasing CO2 gas in the process and losing an active hydrogen:

COOH-H2OC-H2C-COOH ==>

CH3-H2OC-COOH + CO2

However, there's no reason to

Because malic acid is generally a minor component of the TA there will usually be only a slight decrease in the TA upon completion of ML.

Tom S

Salut/Hi Tom S,

le/on Sat, 17 Apr 2004 18:41:03 GMT, tu disais/you said:-

Aha!! Thanks.

Blast, yes of course, stoopid mistook.

Given that I misunderstood TA to mean total acidity. not titrable acidity.... Sigh. And I'm sure I've seen references to TA meaning Total Acidity. Never mind.

I hope therefore that between us, vino has a better idea.

The concept of pH is quite general. It is related to the concentration of H+ hydrogen ions in a solution on a log scale so that the numbers cover a convenient range rather than having to write many leading and trailing zeros. Actually we must consider the concept of activity rather than just simple hydrogen ion concentration, but this is meaningless to those who have not studied physical chemistry or chemical thermodymaics, and concentration is close enough for most practical uses. The reference standard for pH involves use of standard hydrogen electrodes using a reference solution and a standard solution, and measuring the electrical emf generated. I did this once in a physical chemistry course lab, and it is anything but user friendly. The so-called glass electrode made pH meters possible for laboratory use without so much bother. With modern electronics, pocket pH meters are possible, and one good enough for most practical industrial and home purposes can be had for under $US 100 these days. To be accurate, they must be tested against a standard buffer solution from time to time and adjusted to give the corect pH for the buffer. In addition, there are pH paper strips to be dipped into a liquid. They give different colors for different pH ranges. There are wide range strips to get the approximate pH and narrow range strips to more accurately approximate the pH. The strips are good enough for many industrial applications.

Liquids that have a pH below 7 are called acids. The lower the number, the stronger the acid. Liquids with a pH above 7 are called bases. The higher the number, the stronger the base, with 14 being at the top.

Here are a few approximate pH values for several common substances to give you a feel for the range. These are taken from the 64th ed. of Handbook of Chemistry and Physics.

The pH values for acids to follow are of the same concentration(0.1 N) unless otherwise noted .

Hydrochloric -1.1; Tartaric,Malic,Citric - 2.2; Acetic 2.9; Carbonic(saturated) - 3.8; Boric - 5.2. Thus hydrochloric acid is very strong and boric acid is quite weak.

The pH values for some 0.1 N bases follow.

Sodium hydroxide(lye) - 13; Ammonia 11.1; Sodium Bicarbonate(baking soda) - 8.4. Thus sodium hydroxide is a very strong base and sodium bicarbonate is a rather weak one.

Typical pH ranges for body fluids follow.

Human blood - 7.3 to 7.5; Human saliva - 6.5 to 7.5; Human gastric contents - 1.0 to 3.0. The stomach produces hydrochloric acid to digest food which makes the stomach contents extremely acid. Other body fluids are introduced and decrease the extreme acidity as the food goes down lower in the digestive system.

Typical pH ranges for a few foods follow

Limes - 1.8 to 2.0; Lemons - 2.2 to 2.4; Oranges - 3.0 to 4.0; grapes -

Keep in mind these are just typical values for foods. You often can find a few exceptions both at the lower and upper end of the range.

I gave you the "practical point of view",, at least i listen rather than show off.

Thanks Tom.

I was going to ask that, as the context of Ian's message suggests pH would rise, lactic being the weaker acid. Just a "slip of the tongue", I'm sure. And thanks Ian, for a good explanation.

Tom Schellberg

To Mr. Vega;

I speak six languages - of which English is my weakest. I consider myself very well educated according to the standards against which I choose to measure myself. I consider myself polite. I am not American. I am not a winemaker. I do not drink alcohol of any type. I am not a scientist.

I stumbled across this newsgroup by chance, whilst researching the usefulness of Usenet in trying to bolster understanding around the world, by taking politicians out of the communication arena, and trying to get thoughtful discussion among the thinking peoples of the world, regardless of race or colour or religious belief or age or gender.

Generally, I have "met" a very diverse range of people, who are tolerant and "free thinkers", some who believe in a "higher being" and others who chose otherwise; from every gradient of the political spectrum.

I have communicated with some of the most highly educated people imaginable (from many locations throughout the world), and some people struggling to make a living in the harshest environments (, yes, some of them within the United States).

However, during my extensive cyber travels, you are totally unique.

You have a mind like concrete - all mixed up and permanently set.

You have such a high opinion of yourself, that no-one else is entitled to any opinion whatsoever.

In the space of a few short weeks, you have successfully agreed - with absolutely no-one.

I have counted over 80 questions posed to you - and you have addressed exactly NONE.

If you are not involved in politics, then you should consider giving up growing grapes and making wine, because you have great skills in this direction..

You have changed tack more times than Magellan, rounding the horn, or an Americas Cup yacht on San Francisco bay.

You, Sir, are the epitome of "The Ugly American".

You are arrogant in the extreme.

You have insulted thousands of honest men by inferred that winemakers are liars and fraudulent - and guilty of the false labeling of alcoholic content of wines - perhaps you judge others by the standards which you yourself set.

I think that you are trying to appear educated, whereas you cannot spell basic words in the English language, which a six year old would have no difficulty with, even in my Spanish speaking country.

Your use of written language is, frankly appalling.

Most "foreigners" communicating within this group are far more literate than you.

I once read that to be a good liar, one must have an excellent memory - Señor having read through some of the most conflicting contributions I have ever had the misfortune to read from one individual, I am convinced that you are either an uneducated fool or a very poor liar or perhaps both.

However, your ramblings have been both enlightening and entertaining, and I have learned much about you.

No matter what anyone says, you are totally convinced that you are the only one on this planet who knows anything.

Of course, some of the great thinkers in history have been likewise afflicted.

And some of greatest fools!

In closing, there has been much humour expressed by various correspondents to your nonsensical postulations: however, my award for the most apt I attribute to the Honorable Peer from the South Pacific who related the story of Hungarian born film director Michael Curtiz.

Mr. Vega, you truly know f--k all.

Los palillos y las piedras se romperán los huesos pero las palabras nunca me lastimarán.

Bahamontes de Toledo

Yes, but the wine has a buffer capacity which means that the relationship between pH and TA is not linear. Thus, one may need to add lots of acid to get a minor change in pH until the buffer capacity is overcome, in which case linearity occurs for a certain interval. The buffer capacity is caused by salts, such as potassium tartrate and potassium acid tartrate in solution. So it's fair to say that titratable acidity is really a measurement of the absolute concentration of the acid anions, whereas the pH is a measurement of the acidic portion of the cation concentration (H+).

Already answered.

Perceived acidity is a complex function of both, but there is no clear relationship such that a sincle perceived acidity can be related to different values of TA and pH. There tend to be other factors as well. Lower pH wines tend to taste "fresher" than higher pH wines at the same degree of perceived acidity.

Craig Winchell GAN EDEN Wines

A left-handed compliment, to be sure. I like it! :^D

Hey, wait a minute. It hasn't been established that VV is an American, so please don't be so quick to blame him on US! He's more likely a Spaniard or Argentinian who was kicked out of his native country for being so obnoxious. I infer that he is not a native of the USA from his grammar and syntax, which strike me as foreign-born.

Tom S

Salut/Hi Craig Winchell/GAN EDEN Wines,

le/on Sun, 18 Apr 2004 08:00:09 GMT, tu disais/you said:-

Absolutely right, and I was fumbling around with this concept, trying to work out how to bring it up. Thanks for doing so with admirable clarity.

Excellent, ad I'm sure you or Mark can explain this last part if anyone doesn't understand.

Well put. I have read of a recent tasting of rieslings. Very interesting, though I doubt that I ought to say more without express permission by email from the person concerned. In this, TA varied from 6.6 g/l to 9 g/l, though I don't know if these were ALL expressed as Tartaric acid, as some were from Europe. At the same time, the pH varied from 2.9 to 3.32, with, not surprisingly the wine containing 9/l having the lowest (got it right this time, dumbo that I am) pH. BUT might surprise, and which I found interesting is that as you suggest, there was no simple correlation between pH and TA.

In fact these two were an interesting pair.

Domaine aaaa TA: 7.4g/l pH: 3.31 Alcohol: 12.6% RS: 6.6g/l

Domaine bbbb TA: 6.6g/l pH: 3.32 Alcohol: 12.6% RS: 2.8g/l

Note that domaine aaaa had quite a bit higher TA, but almost identical pH. The alcohol contents were the same, but yet the sugars were wildly different. While it's logical to guess that the wine with a higher acidity would taste fresher, in the case of these two, I take leave to doubt it. In fact I think the difference in perceived acidity would come from the widely different sugar contents, rather than the acidity, particularly in view of their VERY close pH.

From the figures here, the trick question is, "which of these two wines came from further north?".

Salut/Hi Tom S,

le/on Sun, 18 Apr 2004 11:20:02 GMT, tu disais/you said:-

But wouldn't it be wonderful if someone who IS the "epitome of the Ugly American" turned out not to be American! The ultimate paradox.

Well, I've seen a number of your fellow citizens who have some difficulty with

"Reisling" "Burgandy" "Gewurtztraminer" "Ch Laffitte Rothshild"

to name but a very few.

That said, there is a certain "je ne sais quoi" about his (happily) inimitable phraseology, which makes me suspect that he might not be a native anglophone. If I had to plunge for a country, I'd say "France". In fact, at first I wondered if he wasn't a well known troll from one of the french language news groups, currently posing as a resident of Corsica.

Salut/Hi bahamontes,

le/on Sun, 18 Apr 2004 18:58:49 +1200, tu disais/you said:-

GULP!!

What a relief! A tiny error in your otherwise impeccable English. (Unique is like pregnant, it's not quantifiable - either you are or you ain't!). But my relief is also due to you sharing my feelings about him.

Pretty dense, too. A truly serendipitous definition.

And some of the most dangerous.

Which gives us two wonderful epithets for the gentleman. Mr Vincent "concrete" Vega, or Vincent "f*ck everything" Vega.

How very true, which is why I've never understood the stiff penalties for libel.

By the way, does that saying exist in Spanish? It's a well known British one certainly.

Thank you very much for your very understated and moderate assessment of our resident fool.

feel free to post 1 or 80. I will reply to whatever you post as I have always done.

Gentlemen, gentlemen--killfile the troll and please move on--you are just encouraging it!

Didnt someone say that than Ian said he was wrong?

Ian,

Call me a fool if you like,, but I understand your resentment against Americans being that you are a lying, French bastard. I have nothing in common with you, nor do I want to. I take a Frenchman's disagreement with me as a compliment. Your live in a nation of pigs and scoundrels yet you call yourself superior. I don't like your kind and I don't like your nation. If it wasn't for the USA you would be drinking German beer and burning Jews. I understand your jealousy,, but attacking me wont make up for what you and your country lack.