Retyped from Wine Analysis Bulletin, by Harold E Applegate, with permission
from American Wine Society ,
Total acidity as tartaric acid in must or wine:
Reagents: 0.1Normal (N/10) sodium hydroxide (NaOH)
phenolphthalein in 95% ethyl alcohol
1. Must or white wine: First clarify the must or wine by filtration
through Whatman #1 filter paper or by centrifugation. The latter method is a fast and most efficient
method for those who can afford a small clinical centrifuge. Add 5 ml of must or wine to 75 ml of boiling
distilled water followed by 5 drops of phenolphthalein indicator. Agitate well and continuously.
Titrate with N/10 NaOH to the faint pink endpoint stable for at least 1 minute.
Volume of NaOH used X 0.15 = grams of acid/100 ml of must or wine.
2. Red Wine: Add 5 ml of red wine to 75 ml of boiling distilled water and with adding
the indicator, titrate with N/10 NaOH until the solution is blue-green in color. Now add 5 drops of
phenolphthalein indicator and complete the titration to the pink endpoint. The endpoint is very tricky and
requires practice. One way to avoid the difficulty is to stir the red wine vigorously with a little bone
charcoal and clarify as done initially. The resultant decolorized wine is then used as a white wine.
Use the same equation that was used for white wine to calculate the
result. (end of AWS excerpt)
For red wine (and white also) Tom will filter the juice or wine that he is taking the sample from
through multiple layers of cheese-cloth, drawing his 5 ml sample with a pipet or a syringe. He uses a
graduated beaker or a white interior container for the test. The use of boiled or hot distilled water
drives off any CO2 that may be in the wine/water. CO2 present in the sample will give a
false reading. CO2 is less soluble in hot than cold and will go off.
The amount of water for the test is not important. 75 ml is fine for a white wine test, but
for a red wine he uses 150 ml of water to dilute the color. Very dark red wine is almost impossible to do
without a pH meter.
When titrating a red sample without a pH meter, Tom adds the 5 drops of phenolphthalein
when his sample turns a tinge of green and holds for a while. The end point then is very near and is easier
He uses the pH meter to determine the end point in red samples. If using a pH meter, color
indicator is not even necessary. So he titrates and agitates the sample with the pH meter probe in it.
The pH endpoint is 8.2. Isn't that wonderful? Plus we have a magnetic stirrer and a self-leveling buret
that we picked up used from a lab. These tools definitely make the task easier. Tom and several of
our winemakers use 8.2 as the end point when testing with use of the pH meter. 8.2 is the end point of the
color indicator, phenolphthalein.
(I have in the past indicated the end point as 8.4, which was in text of Technology of Wine
Making by Amerine, Berg and Cruess, AVI publishing Co. 1972. Our advance amateur winemakers, when asked, use
8.2, but don't know the original source of their information!)
To calculate the acid reading (tartaric) TA, multiply the amount of NaOH used by
Sodium Hydroxide Reading Chart-Click
Read about how to test your Sodium Hydroxide in the Test chapter, also.
Acid test kit instructions that come with the titration kit:
The ideal total acidity of a finished wine ranges from about 0.6% to
0.8%, expressed as tartaric acid (TA).
A fresh juice should run 0.1 to 0.3% higher because some acidity is
lost by the completion of the winemaking process (fermentation and cold stabilization).
This TA test will permit you to make prudent corrections with unbalanced
musts or wines and to indirectly observe the progress of Malolactic fermentations as well as spoilage by
vinegar production. Vinegar production is marked by an increase in acidity in the wine.
Equipment included in your kit: Buret with stand and rubber tubing, glass
end and a clamp (pinchcock), 5 ml pipet, N/.10 sodium hydroxide, color indicator (phenolphthalein).
Also needed to run this test: distilled water, beaker or glass
container, clear or white.
Procedure: For white
wine or juice:
Fill the buret with sodium hydroxide. Run enough through the
buret so that no air bubbles remain below the pinchcock or stopcock.
Using the pipet, add 5 ml sample of the wine or juice to test into the beaker or glass.
Add about 100 ml to distilled water to the wine or juice sample. The amount of distilled water used (more or less) will not change the
result of the test. If using boiled tap water, please
note: The pH of tap water may vary from pH7. If you use it instead of distilled water, you should use the same
volume each time and run a blank test with just the water to see what correction you should
make. The amount of NaOH used should be subtracted from the
amount used in the test for the wine or juice. If the
phenolphthalein turns the water pink before any NaOH is added, you won’t be able to use it.
Add about 5 drops of phenolphthalein indicator to the sample.
Place the wine-sample container under the buret. Record the
sodium hydroxide (NaOH) level in the buret before starting.
Begin running NaOH into the sample. This will cause it to
turn pink. Upon stirring or swirling the sample, the pink
color will disappear quickly. As you approach the end point
the pink takes longer to fade. The end point is the first
faint pink blush that won’t fade within 20 seconds.
Upon reaching the end point, record the level of NaOH in the buret. Subtract your first reading from this to determine the number of ml of
NaOH. The milliliters of NaOH times (X) 0.15 equals the
percent acidity expressed as tartaric acid.
(Example: 4.8 ml X 0.15 = 0.72% acidity or TA)
Procedure for red wine or juice:
Follow steps 1, 2,
and 3 as above for white wine.
- Do NOT immediately add the phenolphthalein indicator as you would with
a white wine or juice. The red pigments make it difficult
to see the end point unless you first titrate the NaOH without the phenolphthalein until the color
turns from red to a blue or green. Only then will you add
the indicator and then continue to the first pink that persist. If the sample is deeply pigmented, you can dilute it with more
distilled water, which does not affect the result of the test. A bright light under or behind the sample also helps.
Tom uses the pH meter to determine the end point in red samples. If
using a pH meter, color indicator is not even necessary. So he titrates and agitates the sample with the
pH meter probe in it. The endpoint is 8.2. Isn't that wonderful? Plus we have a magnetic
stirrer and a self-leveling buret that we picked up used from a lab. These tools definitely make the task