How to Measure Acidity in Wine
The Role of Acids in Wine |
Recommended Acidity Levels
Measuring Acid Using Titration | Measuring
Acid Using a pH meter
Adjusting Acid Levels in Wine |
The Role of Acids in Wine
Before we jump into our discussion of how to measure acidity in
wine, it's paramount to first understand why acid levels are important
to the winemaker.
Acidity provides the crisp, slightly tart taste of wine on your
palate. Too little acid, and your wine tastes flabby and non-committal.
Too much acid, and your taste buds scream for relief. When acids
are properly countered by the other ingredients in wine (such as
alcohol, sugars, trace minerals, etc.), the wine is said to be "in
balance", which is the desired end result of all winemakers.
Now that you know how acids impact a wine's taste, which acids
are found in wine? Acids are present in wine in many forms, but
the largest percentage of acidity (at least in wine made from grapes)
comes from three primary types of acid:
- Tartaric acid
- Malic acid
- Citric acid
You may have seen or heard of a product called acid blend*,
which is nothing more than a powdered mixture of the three acids
listed above. If after conducting an acidity test of your wine,
you discover that your wine lacks the correct amount of acid, the
simplest solution would be to add an appropriate amount of acid
blend to your must prior to fermentation. But we can't do that unless
we know our desired acid levels.
Recommended Acidity Levels
Since each style of wine (red vs. white; sweet vs. dry) is made
to taste different, it makes sense that each wine style would have
its own range of recommended acid levels.
The chart below provides guidelines for acidity based on the type
of wine you are making. Individual tastes vary, of course, so the
information shown are recommendations only:
Recommended Acidity Range
Dry White Wine
0.65 % - 0.75 %
Sweet White Wine
0.70 % - 0.85 %
Dry Red Wine
0.60 % - 0.70 %
Sweet Red Wine
0.65 % - 0.80 %
Sherry Grape Wines
0.50 % - 0.60 %
Non-grape White Wines
0.55 % - 0.65 %
Non-grape Red Wines
0.50 % - 0.60 %
*The chart above was provided by Jack
Keller's terrific winemaking web site
The numbers in the chart represent total acidity as a percentage
by volume; winemakers refer to this as the titratable acidity,
or T.A. for short.
If you're making wine from a grape concentrate kit like the ones
sold on this site, you won't have to fiddle with measuring and adjusting
acidity and pH. This has already been done for you by the kit manufacturer
- the grape juice is already chemically balanced. On the other hand,
if you make wine from scratch, read on to learn more...
There are two basic ways to measure acidity: measure it with a
titration kit or a pH meter. Next, we'll explain how to perform
How to Measure Acidity Using
a Titration Kit
One of the simplest and most effective ways to measure T.A. in wine
is by the titration method, which uses an inexpensive titration
or acid test kit. These test kits can be purchased for as little
as $10.00 or so (see our Item #2716) and can be used over and over again.
If you took chemistry in high school, you'll probably remember
that titration is a process where you determine the concentration
of an unknown substance in a liquid (in our case, we are looking
for the amount of acid in must or wine) by slowly adding a small
amount of reagent (a base called sodium hydroxide - NaOH - whose
chemical concentration is known) until a change in color occurs
due to the presence of an indicator (phenolphthalein).
To begin the test, you will draw a 3 cc sample (one cc equals
one ml) of must into a test tube. Most test tubes that come with
the acid test kits are marked with a line indicating this volume.
If not, no sweat. Just use a small plastic syringe (provided) to
precisely measure the desired amount into the test tube, and be
sure to rinse the syringe afterwards.
Next, put about 3 drops of phenolphthalein indicating solution
into the test tube. Swirl or shake the test tube so the indicator
is mixed in with the must.
Using the syringe, draw out 10 cc of reagent (0.10 Normal sodium hydroxide),
making sure there are no bubbles in the liquid. Be careful to avoid
contact with your skin or eyes. This NaOH stuff burns something
Very carefully (and slowly), add the sodium hydroxide to the test tube a small bit (0.5 cc)
at a time. After each addition, swirl or shake the test tube to
mix the contents together. You'll notice that the color of the liquid
will momentarily change upon the addition of reagent. If you are
testing white wines, the color change will be pink; if testing reds,
the color change will be gray. Just swirl and swirl after each addition until the color
subsides. The longer it takes for the color to dissipate between additions, you should slow down your addition of the reagent to one drop at a time. So long as the color of the must goes back to the original
color, repeat this drop-by-drop step until the color change is permanent.
When the color (either pink or gray) DOESN'T go away, stop and
determine the amount of reagent used. From here, it is very simple
to determine the acidity of your must with an easy mathematical formula. Take a close look at your syringe and determine the amount of NaOH used (NOT the amount left in the syringe). For each ml of reagent used,
multiply it by .25 to find the acid content in percentage tartaric.
For example, if you used 2.4 ml of sodium hydroxide to react with
the must, the titratable acidity of your must is 2.4 X 0.25 = 0.6 %.
Pretty simple, eh? Just remember to throw away your sample, since
this stuff is toxic. DO NOT add it back into your must or wine. Any leftover sodium hydroxide reagent that is still in the syringe can be put back in the jar to save for another test.
Lastly, wash and dry your test equipment before storing it away.
If you ever run out of sodium hydroxide or phenolphthalein, just
ask for Item #2717 or #2716P, respectively.
How to Measure Acidity Using a pH
Measuring acidity in wine using a pH meter is very similar to the
titration method explained above, but with a twist: Instead of looking
for a color change (which can be very difficult to determine depending
upon the color of your wine) to indicate the titration is complete,
you simply add the reagent a drop or two at a time until your pH
meter reads 8.2.
Why 8.2? This is the same pH at which phenolphthalein changes color.
If you can afford a pH meter (they can be bought for as little
as $50 or so), this method is a much more accurate way to measure
acidity than the straight titration explanation above. But pH meters
are finicky things, so handle them with care:
- Don't drop the meter or otherwise damage the probe.
- Keep the probe clean and free of debris.
- Always calibrate your meter with fresh buffering solution before
- Be sure to stir the sample thoroughly after each addition of
- Store your pH meter in the manner recommended by the manufacturer,
especially regarding the care of the probe.
If you take good care of your pH meter, it should last a long time.
Adjusting Acidity Levels in Wine
Once testing is complete, you will know what your acid levels are.
Compare this value with the suggested T.A. ranges in the chart shown
If you need to increase acidity:
- Add acid blend (Item #2729 [1 lb.] or Item #2730 [3 oz.]) to
- 3.9 grams of acid blend will raise the acidity of ONE gallon
of must by 0.1 %.
As a helpful hint for those who do not have scales, 1/4 teaspoon
of acid blend weighs approximately 1.2 grams; a teaspoon weighs
about 5.1 grams.
If you need to decrease acidity:
- Add calcium carbonate (Item #2748) to lower acidity, but only
to reduce acidity by 0.4 % or less.
- 2.5 grams of calcium carbonate (commonly referred to as chalk)
will lower T.A. of ONE gallon of must by approximately 0.1 %.
- Alternatively, you can add a chemical called Acidex in place
of calcium carbonate. Refer to the manufacturer's instructions
for proper dosage.
One-fourth of a teaspoon of calcium carbonate weighs about 0.5
grams; one teaspoon of calcium carbonate weighs about 2.6 grams.
- Until you get the hang of it, test your must twice to be sure
of an accurate reading.
- If you need to make an adjustment to the must based on your
testing, go slow and lean when adding acid blend or calcium carbonate
(as the case dictates). You can ALWAYS add more chemicals to make
further adjustments, but if you overshoot your mark it's difficult
to take it out!
- Take a follow up sample to see how your adjustment went.
- Keep good records so you can duplicate or adjust future batches
*Many wine recipes call for the addition of
acid blend during the workup of the must. The worst
thing you can do is to blindly add acid blend (or any other chemical,
for that matter) simply because a recipe calls for it. You should
always test your must for acid and pH levels before you make any
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