How to Correctly Adjust pH ?

[freddie]

Just picked some Shiraz and took some readings. Baume was 13.5. pH came in at 3.92 which is out of the ideal range. Also took readings for Sangiovese which came in at 3.55. I'm using a Hanna portable pH Meter, and, I may add might have to be re calibrated.

So I targeted a pH of 3.6 at crush. So for 45L of must I added 144g of Tartaric Acid. The next day at the onset of fermentation, my new pH reading is 3.32.

Now either my pH meter is wacho or I've added too much tartaric acid or something else is happening that I don't know about & don't understand.

Something that I've never been clear about is whether to use the volume of must or the expected volume of finished wine in doing these calculations and adjustments.

So, what happens now ?. Will the pH change after fermentation is complete, or do I need to do something else to bring the wine back into acceptable limits.

 

[mmadmikes1]

PH changes when fermentation starts going.

 

[grapeman]

You will be alright where it is. Like mmadmikes said it will change during fermentation and it should end up in an acceptable range. It will taste tart when first finished fermenting. That is expected and it will mellow out in the bottle. A good Shiraz will take at least a year in the bottle before getting good and maybe more.

 

[Turock]

I wouldn't try changing anything--that range is actually pretty good, and as Mike said, the PH will alter slighty as it undergoes fermentation and all the fruit gets broken down.

 

[robie]

As mentioned, you are OK where things are.

In the future, when you make acid adjustments, calculate exactly what you need to add, but add only half that amount. Then, retest and adjust again if necessary.

The reason is each wine is different and there are many different things that can affect the results. For this reason, it is very difficult to calculate the exact dosage.

 

[freddie]

Thanks for the helpful pointers.

What about the basis of calculation. Should acid adjustment calculations be based on "must" volume or approximate finished wine estimate.

What is the correct basis for calculation.

 

[GreginND]

Thanks for the helpful pointers.

What about the basis of calculation. Should acid adjustment calculations be based on "must" volume or approximate finished wine estimate.

What is the correct basis for calculation.

You will probably get different answers about this. But here's mine.

I think you should do adjustments first based on your best estimate of the liquid volume you have at the time. So I would say do not adjust based on the total volume of the must.

If there is an error, you are erring on the side of not adding enough rather than too much. The former you can fix. The latter you cannot.

Actually, it's good practice to do your calculation and add half (or something less) the amount first and retest.

 

[ShawnDTurner]

Even with a PH of that value, if you take it through MLF the PH will rise. This is a common practice in the Wine Industry. Often an adjustment is made with the understanding that either MLF or Cold Stabilization will be done, thus changing your PH value.

 

[freddie]

So do I do my calculations based on the expected liquid volume and then add half, or must volume and half of that ?.

Either way, I'd like to be sure I am adopting the right procedure that will enable corrections to be made later on if need be.

 

[ShawnDTurner]

I second GreG

 

[phineascoates]

Just picked some Shiraz and took some readings. Baume was 13.5. pH came in at 3.92 which is out of the ideal range. Also took readings for Sangiovese which came in at 3.55. I'm using a Hanna portable pH Meter, and, I may add might have to be re calibrated.

So I targeted a pH of 3.6 at crush. So for 45L of must I added 144g of Tartaric Acid. The next day at the onset of fermentation, my new pH reading is 3.32.

Now either my pH meter is wacho or I've added too much tartaric acid or something else is happening that I don't know about & don't understand.

Something that I've never been clear about is whether to use the volume of must or the expected volume of finished wine in doing these calculations and adjustments.

So, what happens now ?. Will the pH change after fermentation is complete, or do I need to do something else to bring the wine back into acceptable limits.

I think everyday you have make some output so that you will notice of what is new and it will help you to recognize also. Therefore, try to make some adjustment of your process.

 

[whackfol]

What was your assumption for your addition? You added 144 g tartaric to +/- 30L finished wine or 4.8g/L. How did you figure this would change your pH from 3.92 to 3.6?

I ask because pH is a non linear scale and I have never heard of an addition method/calculation to adjust pH to a specific number. TA measurements are linear and additions calculable. Their specific impact on pH is a mystery to me. pH is my main gauge for acidity. to me it is more meaningful than TA. Every year I have to be very careful to add a little and taste and test. I'm usually well below what I expect to want when fermentation begins. Once it starts, I don't take readings until after fermentation and ML.

 

[sdelli]

When making corrections, consider the varietal. Seed/skin to juice ratio varies for each grape. We will only be getting around 3 (Bordeaux) to 3.5 (Zin and Rhône)* gallons of finished wine from every 5 gallons of must! This comes out to 60-70% of the must volume. Don’t forget to take this into account when making corrections to the sugar levels or pH/Total Acidity (TA). In addition, most products designed to go into the must should still use the entire must volume to calculate their dosage. This compensates for the portion of the additions that physically bind to the must itself and will not make it into the final wine volume. This includes SO2, enzymes, tannins, oak, Opti-Red, Booster-Rouge and Noblesse.
* Common examples of Bordeaux grapes are Cabernet Sauvignon, Cabernet Franc, and Merlot. Rhône varietals include Syrah, Grenache, Mouvèdre, and Pinot Noir.

 

[sdelli]

3.8 grams Tartaric Acid per US Gallon raises TA by +.1% (1 g/L)
If you don‟t have a scale:
1 level teaspoon Tartaric Acid per US Gallon raises TA by +.12% 1 tsp Tartaric acid = 5 grams.

 

[sdelli]

The importance of correctly preparing a sample for both the TA and pH testing: TA and pH are sensitive tests. It is important to properly prepare samples or we may get false results. With red wines, it is best to get a sample of the must and lightly run it through a blender. The blender serves to open the skins and simulates the chemical make-up the juice will attain once fermentation has completed. The blended sample will need to be strained because the grape solids all have a different pH and TA than the juice itself. If they remain in the sample, they can skew the results. We only want to test the final liquid that is free of solids. To achieve this, first strain the blended fruit to get the solids out. A fine mesh bag (Bag10) is great for this. Next, filter the resulting liquid to obtain a clean juice free of particles. (Paper coffee filters pushed into a wine glass are great for this). The resulting clean juice is optimal for TA and pH determinations.