Really Struggling with Acid Test

[jsbeckton]

I have a kit wine that I cold stabilized and I think it was likely a mistake because it seems a bit dull now. pH is about 3.6 so was thinking that it might need a bit of acid so I got an acid test kit. If I go by the color change it’s coming out to be about 0.56g/l but I have read that the pH being 8.2 is a bit more reliable so I also checked the pH when the color changed and it was only 7.2. If I add more NaOH to get to 8.2 the TA comes out to be 7.1g/l which is pretty good.

Well, which one do I trust? I have repeated the test several times with similar results for each and I also bought new NaOH as well as pH buffer solutions to see if those were off.

As it stands I have no confidence in either method which makes me hesitant to try to make all grape wine where things will not be balanced for me.

 

[mainshipfred]

There are so many conflicting thoughts when it comes to making wine but I think this one is the most agreed upon. Go by taste and not numbers. Pitch a little tartaric in some samples and see what you like. Then test the ph adjust accordingly with 1/2 to 3/4 the bulk amount.

 

[Scooter68]

At a pH of 3.6 you are within the range for starting most fermentations. Normally the number drops considerably as the ferment progresses.

Remember you want MORE acidity not less. You want acidity roughly between 3.00 and 3.6. Not anywhere near 6, 7, or 8

 

[jsbeckton]

At a pH of 3.6 you are within the range for starting most fermentations. Normally the number drops considerably as the ferment progresses.

Remember you want MORE acidity not less. You want acidity roughly between 3.00 and 3.6. Not anywhere near 6, 7, or 8

Thanks. I’m in the bulk aging state. I noted I was at pH of 3.6 and wanted to be a bit lower so not sure where you thought I wanted to be at a pH of 6-8?

*edit* I think you misinterpreted the reference to a pH of 8.2 to be the pH of the wine. That was in reference to the sample once it hit a neutralized stated after the NaOH additions during the acid test.

 

[jsbeckton]

There are so many conflicting thoughts when it comes to making wine but I think this one is the most agreed upon. Go by taste and not numbers. Pitch a little tartaric in some samples and see what you like. Then test the ph adjust accordingly with 1/2 to 3/4 the bulk amount.

Uggh! I don’t trust my taste so like to have some less subjective confirmation but it looks like the acid test might not be as reliable.

Seems like the Vinmetrica SC-300 is based on the same principles so that won’t solve this problem either.

 

[Ajmassa]

When are you noting the NaOH needed when going by color change?
If you kept going when you stopped at 7.2 ph would it still be getting darker? That test always seemed confusing, but I thought it was when the color has completely changed and will not get any darker. So maybe the first reading was actually not finished yet and more in line with the meter TA test? Just a thought.

 

[jsbeckton]

When are you noting the NaOH needed when going by color change?
If you kept going when you stopped at 7.2 ph would it still be getting darker? That test always seemed confusing, but I thought it was when the color has completely changed and will not get any darker. So maybe the first reading was actually not finished yet and more in line with the meter TA test? Just a thought.

The acid test says when you see a “permanent color change” so I take this as the first time the grey doesn’t go away after mixing.

 

[Scooter68]

Get a digital pH meter. That will end the guesswork for both pH and TA testing.

That way you are not working with ambiguous color interpretation. thanks

 

[Ajmassa]

The acid test says when you see a “permanent color change” so I take this as the first time the grey doesn’t go away after mixing.

I always took it to mean when you’ve added NaOH to the point where the color stops changing. On red wine it looked like a dark green almost black. Keep adding until stops getting darker.
Could be the difference between those two TA levels. I would trust The TA result from the ph test over color change test that still read 7.2ph. I think you were just stopping short.
But definitely test a couple samples with tartaric. I used 100mL samples for it. 1/2g/L might make a huge difference

 

[jsbeckton]

Get a digital pH meter. That will end the guesswork for both pH and TA testing.

That way you are not working with ambiguous color interpretation. thanks

Have one as noted. Are you saying that the color test can be consistently that far off from pH test? Or maybe the instructions on the color test are just to vague to know when the test is complete.

 

[mainshipfred]

Have one as noted. Are you saying that the color test can be consistently that far off from pH test? Or maybe the instructions on the color test are just to vague to know when the test is complete.

My problem is I'm a little or maybe a lot color blind. I need the digital readout ro do the testing.

 

[Scooter68]

The numbers are very straight forward to read. If your wine isn't a white wine color changes can be easy to miss or misread.
The only mistake with a digital meter is not stirring enough and waiting as you add the sodium hydroxide. When you get close to that target number things change quickly so you have go slower and stir more.

Also you are looking for a number not a color

 

[jsbeckton]

Also you are looking for a number not a color

To be clear, I am taking about 2 different methods and in one of them you most certainly are looking for a color. This one seems to be a lot more subjective and less accurate.

 

[Scooter68]

When you use a pH meter to measure TA you are not watch for a color change. You are adding sodium hydroxide until the pH meter reads 8.2.

Suggest you research the steps for this. I'm on the road and don't have access to my PC to post the process steps. No dilution needed and you only use sodium hydroxide.

Save yourself the guesswork of watching for a color change in a dark wine and look it up. Perhaps someone else can provide the link for you.

 

[jsbeckton]

When you use a pH meter to measure TA you are not watch for a color change. You are adding sodium hydroxide until the pH meter reads 8.2.

Suggest you research the steps for this. I'm on the road and don't have access to my PC to post the process steps. No dilution needed and you only use sodium hydroxide.

Save yourself the guesswork of watching for a color change in a dark wine and look it up. Perhaps someone else can provide the link for you.

Rest assured that I am already well aware that you are not watching for a color change when using a pH meter.

I think you are confusing my questions about 2 totally different methods to apply to one method.

I think the answer to my question is that the color change method is less accurate than the pH method.

 

[Scooter68]

Not confused at all.have a great day

 

[Rice_Guy]

Rest assured that I am already well aware that you are not watching for a color change when using a pH meter.

I think you are confusing my questions about 2 totally different methods to apply to one method.

I think the answer to my question is that the color change method is less accurate than the pH method.

* When the color of phenolphthalein changes is should be quickly with a drop, it is normal for the color to fade as salt forms react. The normal test with phenolphthalein and a red wine will have you dilute in distilled water such that you can see the endpoint. (phenolphthalein will change from clear to pink at pH 8.2)
* Titration curves using a pH meter are attached. Expect that a red will titrate faster than a white and that a northern hybrid will be slower yet. Again you can see that the end point comes with a couple drops when you are at pH 7 or higher.

 

[Rice_Guy]

jsbeckton, * I agree with the second post which says that the way to find what tastes good is to taste it. Lab people come up with tests for hourly technicians to run so we can document something easily, ALWAYS the test is intended to reflect what the food is like for the home consumer. I have a taste panel which is my wife and any of her friends in the house while I have a bench trial set up.

* TA and ph are complicated since they are different with every crop year and variety. Roughly the acid H+ (ie a pH measurement) will have ten times the flavor impact that the salt of the acid does (ie a TA measurement). To complicate the system roughly 100 times more salt form of the molecule exists in grape juice so-ooo the TA has a larger impact, ,, which I would call "depth" of flavor (or how long it takes to wash off the taste buds in your mouth) There are different strengths of acids in grapes which all ionize to different degrees (called pK and for di acid pK2 etc) and the percentage in the juice will vary with the ripeness, variety, crop year etc. - - - - - ie acids are a mess and it is hard to write a one factor A+B=C rule on how to fix acid levels. - - - - - another way to say this is that by the numbers doesn't always work the same. If I add a strong acid (H+2 SO4 [ a very strong acid] by dosing with gypsum I could add a lot of the stronger acid flavor H+ ions without changing the TA significantly, Lactic is a weaker acid so the reverse situation)
An easy to read reference with 5 gallon size examples of how to, is: "Modern Winemaking" by Jackish; chapter 7 Adjusting Wine Acidity.

* Good luck but then this is part of the fun of wine, it is a complicated system. We are artists as much as folks who measure.

 

[Rice_Guy]

TA test for me
* weigh 15.00 gm (15.0 ml) into a round bottom glass
* place pH meter in glass (if needed add more distilled water to cover probe)
(optional add phenolphthalein)
* fill syringe (burette) with 10 ml of 0.2N sodium hydroxide (about $5 per bottle at my local wine toys shop). Slowly add sodium hydroxide to sample as you swirl. When you are at pH 7 slow down ie add ONE drop swirl till pH is stable add ONE drop swirl etc.
* With 0.2 normal sodium hydroxide and 15 gm (15 ml) of sample 1.0 cc of titrant equals 0.1% TA as tartaric acid,,,,,,, I like easy math ,,,,,, I have sometimes weighed the finished glass and skipped reading the burett (syringe)
**************************************************************
The vinmetrica procedure is attached. It uses a different concentration of sodium hydroxide 0.133 N (which is not stocked by my local wine toy shop) and a 5.0 ml (5.00 gm) sample, therefore the math is different,, but the concept is exactly the same.

 

[jsbeckton]

TA test for me
* weigh 15.00 gm (15.0 ml) into a round bottom glass
* place pH meter in glass (if needed add more distilled water to cover probe)
(optional add phenolphthalein)
* fill syringe (burette) with 10 ml of 0.2N sodium hydroxide (about $5 per bottle at my local wine toys shop). Slowly add sodium hydroxide to sample as you swirl. When you are at pH 7 slow down ie add ONE drop swirl till pH is stable add ONE drop swirl etc.
* With 0.2 normal sodium hydroxide and 15 gm (15 ml) of sample 1.0 cc of titrant equals 0.1% TA as tartaric acid,,,,,,, I like easy math ,,,,,, I have sometimes weighed the finished glass and skipped reading the burett (syringe)
**************************************************************
The vinmetrica procedure is attached. It uses a different concentration of sodium hydroxide 0.133 N (which is not stocked by my local wine toy shop) and a 5.0 ml (5.00 gm) sample, therefore the math is different,, but the concept is exactly the same.

Thanks. I presume that the remaining steps say to stop at pH=8.2 and then do the math correct? I already have a pH meter and a magnetic stirrer so I can prob get away with a lesser model when the time comes to invest in one.