TA acid text PH meter method/calc?

[JamesdNorcal]

I just wanted to check if I’m doing my TA test/calcs correctly with my PH meter.

1. I calibrated my PH meter
2. I added 5 ML of wine must
3. I added .1N sodium hydroxide until 8.2Ph..added 8ML to get to 8.2PH.

8ML .1N Sodium hydroxide / 5ML juice X .75 = TA of 1.2% or 12.??

is that correct? Thanks!

 

[stickman]

The calculation looks correct to me, that's 12g/l as tartaric acid.

 

[JamesdNorcal]

Thanks.. yep, It’s my barbera. PH is still on the low side 3.24 and high acid. I added a little potassium carbonate to help. I’m adding in VP41 for ML and cold stabilize later hopefully acids will come down. I’m about done with primary after 7 days. 2 brix, gravity 1.02 so the yeast got through the high acid/low ph. It’s definitely a little tart.

 

[Johnd]

The calculation looks correct to me, that's 12g/l as tartaric acid.

Thought “TA” was Total Acidity......????

 

[sour_grapes]

I think it is really "titratable acidity," but expressed in g/l as if it all the acid were tartaric acid (hence @stickman 's reference).

 

[Johnd]

I think it is really "titratable acidity," but expressed in g/l as if it all the acid were tartaric acid (hence @stickman 's reference).

I sort of asked the question to push the issue a bit. You can find reasonable references for all 3, Tartaric Acid, Total Acidity, and Titratable Acid. Personally, I’ve always accepted the last two as nearly the same, since they both recognize the presence of more than just Tartaric Acid in grapes, though Tartaric is predominant.

Makes me wonder, when we perform our titrations to determine TA, aren’t we titrating out all of the acids present to get to pH 8.2, or are we only titrating out the Tartaric. I don’t recall ever learning that. Maybe @stickman has it right, he usually does, LOL!!

 

[Rice_Guy]

The taste buds on the tongue don’t discriminate whether it was an acid ion from citric or phosphoric or tartaric or malic or sorbic. BUT, ,,, TA is a convenient unit for measuring the impact acid ions have in the mouth and comparing one food with another. (yes I look up a lot of TA numbers and technically if I am counting the alkaline ion they are wrong)

TA is also a bad system since your mouth is not pH 8.2 and we knew from the start that several grape derived acids were being lumped into one number, and IF we are country wine makers the wine really doesn't have much/ any tartaric acid and if the sample is dark it is hard to see an end point.

BUT,,, TA is a good system since a hundred years ago a phenothalene end point was reproducible/ readily available from the chemical supplier ,,, and sodium hydroxide was reproducible ,,, and TA gave us a language which could compare sensory impact across foods.

 

[Rice_Guy]

There are several procedures available. The one I started with uses 0.2 normal sodium hydroxide (which is available from my local wine toys store). Also it uses 15 cc/ml of sample (which is over kill measuring lemon or cranberry so I routinely test smaller samples and multiply a correction)

*Vinmetrica uses different different sample size and concentration of sodium hydroxide, and we don’t have to read pH or color since it beeps.
*The lab procedure from our 100 year old book of methods had us mix up sodium hydroxide and then standardize how strong it turned out this time with succinic acid and then put that normality in the formula, ,,, at least till we mix up more reagent.
*A good procedure first and foremost is reproducible and next is easy.

 

[Scooter68]

So.... from what I gather - TA for Country Fruit Wine makers is not all that great a method. We would be better off with non-grape wines to use pH and refine with the tongue?

 

[Rice_Guy]

TA is a language which would be technically correct if expressed as hydronium ions bonded to an unnamed alkali, instead of tartaric acid molecules which by the way contain two hydronium ions.
TA is totally different from pH and I am periodically flabbergasted that the 5 kg watermelon with a pH of 7 / TA of 0.03% wasn’t overwhelmed by the 4 kg of gooseberry with a pH of 3.49 (ie perfect)/ TA of 2.90%. Math wise I guessed it would fall in place but no.
The flavor impact is also a hard to learn scale, after tasting wine we would guess a cola with a pH of 2.5 would be horrible but since the TA is 0.2% the acidic sensation washes out of the mouth quickly.

So.... from what I gather - TA for Country Fruit Wine makers is not all that great a method. We would be better off with non-grape wines to use pH and refine with the tongue?

I also come out of a perverted background which regularly hires no experience twenty year olds for the MinuteMaid QA lab. ,,,,
TA can give the answer for consumer acceptance without training a kid for two years on how to discriminate taste, soooo. As a measure for flavor impact TA works.

 

[stickman]

@sour_grapes had it correct; I wasn't intending to describe what TA meant. I just indicated Tartaric acid because the formula shown in the OP includes the constant for the results to be expressed as Tartaric acid. It's just another part of the wine acidity "black hole" of information. The TA can be expressed as any acid, but Tartaric acid is typical in the US, and Europe usually expresses TA as Sulfuric acid.

 

[Ajmassa]

@sour_grapes had it correct; I wasn't intending to describe what TA meant. I just indicated Tartaric acid because the formula shown in the OP includes the constant for the results to be expressed as Tartaric acid. It's just another part of the wine acidity "black hole" of information. The TA can be expressed as any acid, but Tartaric acid is typical in the US, and Europe usually expresses TA as Sulfuric acid.

**2nd edit— I withdraw all questions!

 

[sour_grapes]

Makes me wonder, when we perform our titrations to determine TA, aren’t we titrating out all of the acids present to get to pH 8.2, or are we only titrating out the Tartaric. I don’t recall ever learning that. Maybe @stickman has it right, he usually does, LOL!!

Maybe not necessary at this point in the thread, but let me try to explain my understanding of the metric.

Yes, you are right: you titrate ALL the acids. But what is it that you know/measure? The only thing you know is how much sodium hydroxide you introduced. Some of the alkali ions went to titrate tartaric acid (costing 2 ions/acid molecule) and some went to titrate citric acid (costing you 3 ions/molecule), for example. But you don't know how much of each, you just know how many total alkali ions. How do you choose to express that?

One way is to pretend that tartaric acid was the only acid in the original solution, and to figure out how many tartaric acid molecules it would have taken to absorb all of the alkalis. And then you express that concentration of the (fictitious) tartaric acid molecules in g/l. (As @stickman points out, there are other ways to express that figure of total alkali ions, too.)

 

[stickman]

Are you asking to step into the black hole? The short answer is that Malic acid has two titratable protons and lactic acid has only one.

To some extent, the resulting TA error as expressed as Tartaric is offset by the fact that Lactic acid is lighter than Tartaric acid; Lactic acid 90g/mole vs. Tartaric acid 150g/mole. So 1.2g/l of Lactic acid will show as 1g/l expressed as Tartaric acid.

Edited to include conversion factors below.

 

[Scooter68]

Ok....

 

[Johnd]

I kinda like when posts get a little tricky and we all get to learn some more!! I'll stick with my mental picture of TA being more representative as a measure of all of the acids in a wine, it helps me keep it in perspective.......... Thanks for all of the responses, all very well thought out and informative!!!

 

[stickman]

I agree that there isn't much need to get this involved in the details, but @Ajmassa asked. LOL

I think there is at least one good point to take away from this. If you are doing TA titrations using the standard formula in the US for Tartaric acid, and you are adjusting the must with acid other than Tartaric acid, use the corresponding conversion factor above to better predict the end result. For example, adjusting a country wine with Citric acid, it would take only .85g/l to make a 1g/l change in the TA titration.

 

[Rice_Guy]

I make a motion that we call this the “Titratable ‘A’lack hole” ,,,, who wants to second the motion?

I kinda like when posts get a little tricky and we all get to learn some more!! I'll stick with my mental picture of TA being more representative as a measure of all of the acids in a wine, it helps me keep it in perspective.......... Thanks for all of the responses, all very well thought out and informative!!!

 

[Johnd]

I make a motion that we call this the “Titratable ‘A’lack hole” ,,,, who wants to second the motion?

I'll second that motion!!!

 

[Ajmassa]

Well FWIW I did withdraw my questions after realizing I had my answers but you drug me in the hole anyway @stickman !
What I find kind of odd tho is that it is accepted to use technically incorrect terminology- even by professionals. Tho I do understand it much better now (Both how it can be viewed as an attempt keep it simple for readers and how it’s technically wrong but not harmful **since the entire TA test itself is intentionally proportioned with tartaric acid specifically. So using the term “expressed as tartaric acid” now makes a lot more sense for me rather than simply referring to TA as ‘tartaric acid‘. **

I’m glad you elaborated and posted that table. Lactic “lighter” and malic “heavier” than 1:1 was expected. But learning citric is even stronger/heavier than malic was surprising! Exiting the hole now