Little bit of a problem with TA readings

[Nebbiolo020]

I wanted to get a little feedback because I have a bit of an issue,

I harvested some Zinfandel grapes and cold soaked them for 2 days and just ran the numbers, brix is 26.5, ph tested with a meter and strips is 3.7-3.8 but using a acid titration kit from the local wine shop I’m getting 0.15-0.25 which seems weird to me as I also work at a commercial winery and from my experience if the ph is right then the tartaric should be spot on and I’m getting strangely low readings and I’m unsure if I should add some tartaric based upon the readings because if they are right it will be good but if they are wrong and lying to me then I will have a low ph and possibly too much acid and I’m unsure if I should add it or not I don’t have any labs near me 30 minute drive and I really don’t want to drive 1 hour. What would you do in my situation.

 

[Chuck E]

I wanted to get a little feedback because I have a bit of an issue,

What would you do in my situation.

Your Brix and pH are right in the "sweet spot." I would not adjust anything until after fermentation completes.

 

[Nebbiolo020]

Your Brix and pH are right in the "sweet spot." I would not adjust anything until after fermentation completes.

Okay, usually if I adjust acid I do it prior to fermentation but I’m unsure if the results I got are right so I’m going to wait and see.

 

[winemaker81]

pH and TA are often in sync, but this is not a guarantee as they measure different things. I agree, go with what you have and check after the wine is degassed.

 

[cmason1957]

When you used that acid titration kit, did you try to find the color change by sight or did you measure it, by titration to a ph of 8.2? If the former, I would assume you stopped adding acid to soon.

 

[Nebbiolo020]

When you used that acid titration kit, did you try to find the color change by sight or did you measure it, by titration to a ph of 8.2? If the former, I would assume you stopped adding acid to soon.

I’m going to do one more test just cause I suspect you are right.

 

[Nebbiolo020]

I tested again 3x in a row it indicates after using 1ml of the solution. So it really must be that bad cause the instructions say to take the amount used and multiply by .25.

 

[bluecrab]

Your wine sample and sodium hydroxide should be at room temperature. If not, it can cause a false reading.

 

[Rice_Guy]

* it is more accurate to titrate against the pH meter than against the indicator solution, besides you get both the starting pH and volume of NaOH in one process.
* TA is a chemical reaction with soluble materials which practically speaking is instantaneous , for most chemical reactions we assume that the rate doubles for every ten degrees C, ,,, we will not see a significant change from instantaneous within liquid temperatures. ,,, We will see the effect of how much mixing and if there are particulates as whole grapes in the must or vegetable solids in a pasta sauce kettle.
* cold will influence the pH reading, most $100 meters have automatic temperature compensation in the circuitry.
* most pH meters give two place accuracy so record the extra digit,
* from a northern point of view pH 3.8 is high. With hot climate/ late harvest grapes the pH could be there as measured with a reference lab.
* pH is involved in the efficiency of metabisulphite and as a result oxidation reactions. With country wines I usually adjust the pH to the low end as 3.2 to 3.3 since the metabisulphite works better. With reds 3.8 seems high and you will need more meta.
* on the California juice buckets through the vinters club this year I was getting reds with pH 3.5ish and TA of 0.3%. Likewise whites and Italian juices were low on TA. Your numbers are believable for this crop year. My advice in club buckets is “fix” the pH to the target for metabisulphite in the must and ignore TA till bottling.
* since you work at a winery you likely could have a pH run in the lab as a cross check, a Hach instruments TA is one drop, hopefully that could be run too.
* since you work at a winery, how was the crop coming in? Your local grapes and winery local grapes should be seeing the same climate variation this year.

 

[Nebbiolo020]

Your wine sample and sodium hydroxide should be at room temperature. If not, it can cause a false reading.

Both the solution and wine were in same room at about 65 Fahrenheit.

 

[Nebbiolo020]

* it is more accurate to titrate against the pH meter than against the indicator solution, besides you get both the starting pH and volume of NaOH in one process.
* TA is a chemical reaction with soluble materials which practically speaking is instantaneous , for most chemical reactions we assume that the rate doubles for every ten degrees C, ,,, we will not see a significant change from instantaneous within liquid temperatures. ,,, We will see the effect of how much mixing and if there are particulates as whole grapes in the must or vegetable solids in a pasta sauce kettle.
* cold will influence the pH reading, most $100 meters have automatic temperature compensation in the circuitry.
* most pH meters give two place accuracy so record the extra digit,
* from a northern point of view pH 3.8 is high. With hot climate/ late harvest grapes the pH could be there as measured with a reference lab.
* pH is involved in the efficiency of metabisulphite and as a result oxidation reactions. With country wines I usually adjust the pH to the low end as 3.2 to 3.3 since the metabisulphite works better. With reds 3.8 seems high and you will need more meta.
* on the California juice buckets through the vinters club this year I was getting reds with pH 3.5ish and TA of 0.3%. Likewise whites and Italian juices were low on TA. Your numbers are believable for this crop year. My advice in club buckets is “fix” the pH to the target for metabisulphite in the must and ignore TA till bottling.
* since you work at a winery you likely could have a pH run in the lab as a cross check, a Hach instruments TA is one drop, hopefully that could be run too.
* since you work at a winery, how was the crop coming in? Your local grapes and winery local grapes should be seeing the same climate variation this year.

All my grapes were from the same region this year, my Zinfandel is from the adelaida district In Paso Robles and I hand picked the Zinfandel with the vineyards owner, all of the grapes at work came in over 4.0 ph and required adding tartaric to achieve 3.7-3.8 ph prior to fermentation. That’s where we like to be, pretty much everyone else has been seeing really low TA and ph.
My Syrah which is from the Santa margarita ranch ava came in 27 brix and I watered to 25 and ph was 4.12 so I added tartaric to achieve a ph of 3.72 as TA was really low with lab testing.
So it is possible that the TA is just bad but I’ve been told by winemakers who I have studied under and from my boss that ph and TA go hand in hand and if ph is normal it’s pretty much unlikely for TA to be bad my boss studied under Jeff Cohn.

 

[Rice_Guy]

You are going to be the expert with grape since you have “skilled in the art” at work.

On a clean one component chemical system in distilled water, or a UC Davis model system you can say that they go hand in hand. We however live in the variable world of drought and adding fertilizer and daytime temperature and pick date and different rock under corners of the land, ,,,, so the chemical make up is not clean and will be a dirty soup. Tartaric is involved in precipitation reactions, and has a minimum inflection point in pH vs concentration. Next the plant is working to build acids as a preservative in the green state then remove acids at veraison for seed dispersal so wild life will harvest it, the ratio of acids changes with maturity, ,,, and each acid has different kPa constants which have to balance to yield a finished/ measurable pH and TA. Again potassium and other minerals, they will have buffering capacity which skew the measurable result.
To do a predictive equation one would have to analyze for a dozen molecules, ,,,, and formulas are hard to build once we get past three variables.

So it is possible that the TA is just bad but I’ve been told by winemakers who I have studied under and from my boss that ph and TA go hand in hand and if ph is normal it’s pretty much unlikely for TA to be bad my boss studied under Jeff Cohn.

TA is an extremely easy and reliable test. Your readings are probably correct. If I questioned it I would weigh out acid on the analytical balance and check the math with a known reagent. pH calibration especially with the old tube based meters can be a source of error. ,,,,,
Jackish in Modern Winemaking 1985 and Margalit in Concepts in Wine Chemistry 1997 are good references.