Wine Too Acidic? How to Reduce Acidity

Recognizing Excessive Acidity

When wine is too acidic, it tastes sharp, sour, and biting on the palate. Your mouth may pucker, your cheeks may tingle, and the wine may feel thin and aggressive rather than crisp and refreshing. While acidity is essential to good wine — providing structure, freshness, and aging potential — too much throws the entire balance off.

Titratable acidity (TA) is the standard measurement for total acid content. Most balanced wines fall between 5.5-7.5 g/L TA. Wines above 8.0 g/L are noticeably tart. Wines above 10.0 g/L are uncomfortably acidic for most palates. The pH also matters: most wines fall between 3.1-3.8, with lower numbers indicating higher acidity.

Measuring Acidity Accurately

Before making adjustments, you need accurate numbers. Use an acid testing kit (available from any winemaking supply store) to measure titratable acidity. Use a calibrated pH meter or reliable narrow-range pH strips to measure pH. Record both values — they tell you different things about the acid profile.

Understanding the Types of Acid

Wine contains several acids, but the primary ones are:

• Tartaric acid: The principal acid in grape wines. Stable and clean-tasting.
• Malic acid: Tastes sharp and green-apple-like. Dominant in many fruits and cool-climate grapes.
• Citric acid: Bright and lemony. Common in citrus and some fruit wines.
• Lactic acid: Soft and creamy. Produced during malolactic fermentation.

The type of acid present affects which deacidification method is most appropriate.

Chemical Deacidification

Potassium Bicarbonate

Potassium bicarbonate (KHCO3) is the safest and most predictable chemical deacidifier for home winemakers. It neutralizes tartaric acid and precipitates out as potassium bitartrate crystals (cream of tartar).

Procedure:

1. Dissolve 3.4 grams of potassium bicarbonate per gallon in a small amount of the wine
2. This will reduce TA by approximately 1 g/L
3. Add the solution to the wine and stir gently
4. Cold stabilize the wine at 28-32°F (-2 to 0°C) for 2-4 weeks to precipitate the potassium bitartrate crystals
5. Rack the clear wine off the crystal sediment
6. Retest TA and pH after treatment

Important: Do not attempt to remove more than 3 g/L of TA using potassium bicarbonate alone, as the pH can rise too high (above 3.8), making the wine vulnerable to spoilage.

Calcium Carbonate

Calcium carbonate (CaCO3) is another option that neutralizes both tartaric and malic acid. It is particularly useful when you need to reduce acidity from both sources.

Procedure:

1. Add 2.5 grams of calcium carbonate per gallon to reduce TA by approximately 1 g/L
2. Stir the wine thoroughly — the calcium carbonate will fizz as it reacts
3. Allow the wine to settle for 2-4 weeks in a cool location
4. Rack off the sediment
5. Retest TA and pH

Caution: Calcium carbonate can leave a chalky aftertaste if overused. It can also cause a condition called calcium instability where calcium tartrate crystals form later in the bottle. Always make conservative additions and retest.

Acidex (Double Salt Method)

Acidex is a commercial product that uses a double salt precipitation method to remove both tartaric and malic acid more effectively than single-salt methods. Follow the manufacturer's instructions precisely, as the process involves treating a portion of the wine and then blending it back.

Malolactic Fermentation

Malolactic fermentation (MLF) is a biological deacidification process where specialized bacteria convert sharp malic acid into softer lactic acid and CO2. This effectively reduces the perceived acidity and creates a rounder, creamier mouthfeel.

When MLF Is Appropriate

MLF is ideal when:

• The wine's acidity is primarily from malic acid (common in cool-climate grapes and many fruits)
• You want a softer, rounder wine style
• The wine is a red wine or full-bodied white (MLF is standard for most reds)
• The wine has not been heavily sulfited (SO2 above 15 ppm inhibits MLF bacteria)

How to Conduct MLF

1. Ensure the wine's free SO2 is below 10 ppm and the pH is above 3.1
2. Warm the wine to 65-72°F (18-22°C)
3. Add a commercial malolactic bacteria culture (such as VP41 or CH16) according to the package directions
4. Maintain temperature for 4-8 weeks
5. Monitor progress using a paper chromatography kit — you will see the malic acid spot disappear as conversion occurs
6. Once complete, add 30-50 ppm SO2 to prevent further bacterial activity

How Much Acidity Does MLF Remove?

MLF reduces the contribution of malic acid by converting it to lactic acid, which has approximately 67% of the acidic strength of malic acid. If malic acid was a significant component of your total acidity, you can expect a reduction of 1-3 g/L TA and an increase in pH of 0.1-0.3 units.

Cold Stabilization

Cold stabilization encourages potassium bitartrate (cream of tartar) to crystallize and precipitate out of the wine. This specifically removes tartaric acid and is a natural, gentle deacidification method.

Procedure

1. Chill the wine to 28-32°F (-2 to 0°C) — a chest freezer with a temperature controller works well
2. Hold at this temperature for 2-4 weeks
3. The tartrate crystals will form on the bottom and sides of the container
4. Carefully rack the wine off the crystals without disturbing the sediment
5. Allow the wine to warm to room temperature and retest TA and pH

Limitations

Cold stabilization typically removes only 0.5-1.5 g/L TA. It is not sufficient for severely over-acidic wines but is excellent as a finishing step or for wines that are only slightly too tart.

Blending

Blending a high-acid wine with a low-acid wine is one of the most effective and natural ways to achieve balance. This method avoids chemical additions entirely.

How to Blend Effectively

1. Find or make a low-acid partner wine — ideally of the same type or a complementary variety
2. Conduct bench trials using measured portions: try blends at 10%, 20%, 30%, and 40% low-acid wine
3. Measure the TA and pH of each blend
4. Taste each blend to evaluate overall balance — not just acidity, but also body, flavor, and aroma
5. Scale up the best-performing ratio

A useful formula: Target TA = (Volume A x TA of A + Volume B x TA of B) / Total Volume

Prevention for Future Batches

Test Fruit Before Fermenting

Always measure the TA and pH of your must before fermentation begins. If TA is above 8.0 g/L, consider deacidifying the must before pitching yeast. It is easier to adjust acidity in the must than in finished wine.

Choose Lower-Acid Fruit

Some grape varieties and fruits are naturally very high in acid. Vidal Blanc, Seyval Blanc, and many hybrid grapes can be extremely acidic in cool climates. Blending with lower-acid varieties or selecting riper fruit reduces the starting acid load.

Plan for MLF

If you know your wine will be high in malic acid, plan for MLF from the start. This means keeping sulfite levels low until MLF is complete and maintaining appropriate temperatures.

Harvest Timing

In grape winemaking, later harvest generally means lower acidity and higher sugar. If your grapes are consistently too acidic, allowing them to hang a week or two longer on the vine (weather permitting) can make a significant difference.

Frequently Asked Questions

Can I just add water to dilute the acidity?

While dilution does reduce both acid concentration and perceived acidity, it also dilutes flavor, color, body, and alcohol. Use water dilution only as a last resort and only in small amounts — generally no more than 5-10% of total volume. Other methods preserve wine quality much better.

How much potassium bicarbonate should I use per gallon?

For a reduction of approximately 1 g/L TA, add 3.4 grams per gallon of potassium bicarbonate. Always add incrementally, retesting after each addition. Do not attempt to drop TA by more than 3 g/L in a single treatment.

Will MLF make my wine taste buttery?

It can. The diacetyl compound produced during MLF creates a buttery or butterscotch aroma. Some strains of MLF bacteria produce more diacetyl than others. If you want to minimize butteriness, choose a low-diacetyl strain like VP41 and allow the wine to remain on the bacteria for a few weeks after MLF is complete, as the bacteria will reabsorb some of the diacetyl.

Is it better to deacidify before or after fermentation?

Both approaches work, but adjusting acidity before fermentation is generally simpler. The must is less sensitive to additions, and fermentation itself often reduces perceived acidity slightly. However, you cannot predict exactly how fermentation will affect acid balance, so some post-fermentation adjustment may still be needed.

My wine's TA is fine but the pH is low — what does this mean?

This is common in wines with strong buffering capacity. The wine has significant acid content that is partially neutralized by minerals and other compounds, keeping TA moderate while pH remains low. In this case, small additions of potassium bicarbonate will raise the pH without dramatically changing the TA. Focus on pH as your guide.

Can I use baking soda (sodium bicarbonate) instead of potassium bicarbonate?

It is not recommended. Sodium bicarbonate adds sodium to the wine, which can create a salty taste at even moderate concentrations. Potassium bicarbonate is the proper winemaking product and does not leave undesirable flavors.

How long after deacidification should I wait before bottling?

Wait at least 3-4 weeks after chemical deacidification and complete any cold stabilization before bottling. This allows all crystals to form and settle. Taste the wine, retest TA and pH, and confirm the wine is clear and stable before bottling.

What if my wine is both too acidic and too sweet?

If the wine is both high in acid and high in residual sugar, the two can actually balance each other. Taste the wine critically — the sweetness may be masking some acidity and vice versa. If both are truly excessive, address the acidity first, then evaluate whether the sweetness still needs adjustment.