Acidity Types in Wine

Acids are what make your wine taste refreshing. Their presence makes your mouth water, and they can also play a role in protecting the wine from spoilage. Wine does not contain just one acid but several, and they can be sorted by where they come from: tartaric, malic and citric acids are derived from grapes, while succinic, lactic and acetic acid are formed through yeast and bacterial activity. Tartaric and malic acid are the principal acids of wine. Winemakers usually measure all of these together as titratable acidity (TA), a figure for the total amount of acid that can be neutralised by a base. Total acidity in most wines sits in the range of 5.5 to 8.5 g/L (grams per litre).

• Tartaric acid: from the grape; all wines contain tartaric acid from the grape juice
• Malic acid: from the grape; malic and tartaric are the major acids in grapes
• Citric acid: from the grape, but only present in very small quantities (if at all)
• Lactic acid: made by bacteria from malic acid; all reds and many whites feature lactic acid
• Succinic and acetic acids: formed through yeast and bacterial activity

Tartaric and lactic acids are odourless, and acidity is assessed on the palate. For most people, it creates a sharp, tingling sensation that is felt most strongly at the sides of the tongue. The real giveaway is in your saliva: the more your mouth waters, and the longer it waters, the higher the acidity. A wine that causes little salivation and feels soft and rounded is likely low in acidity. Malolactic fermentation converts sharper malic acid into softer lactic acid, creating a rounder, creamier wine. Acetic acid is different: it is the main part of what winemakers call volatile acidity, which is generally perceived as the odour of vinegar.

• Flavour clues in whites: notes of lemon, lime, grapefruit or green apple suggest a strong acidic backbone; Sauvignon Blanc, Riesling, Chenin Blanc and Albariño often have high acidity
• Flavour clues in reds: bright red fruit such as cherries and cranberries can indicate higher acidity, as in cool-climate Pinot Noir, Sangiovese, Nebbiolo and Gamay
• Malic versus lactic: malic acid is the sharper of the two and lactic acid the softer
• Acetic: its aroma threshold in wine can be as low as 0.1 to 0.125 g/L, and the level regarded as detrimental is usually greater than 0.7 g/L
• Sweetness masks acidity: a wine with high residual sugar can taste balanced even when its acidity is very high, but acidity will still make your mouth water

Climate is the single biggest influence on a wine's acidity. Wines from cooler regions tend to hold onto more of their tartaric and malic acid. As temperatures rise during the ripening period, the vine metabolises malic acid, which can leave warmer regions with lower-acid wines. The same is true of warmer vintages, and grapes picked earlier in the season should retain more acid than those left on the vine for longer. Chablis and the Mosel are the classic cool-climate examples. Winemakers can step in too: in warmer regions they may add tartaric acid in powder form if the grape acid fell too far during ripening, while in cooler regions they can add an alkaline substance to neutralise excess acid.

• Cool climates: grapes ripen more slowly and wines tend to retain more natural acidity
• Warm climates: warmer climates often produce wines with lower acidity, but high altitude and cool night temperatures can preserve freshness
• Vintage variation: malic acid is affected by the growing conditions experienced by the grape

Malolactic fermentation (MLF) is a secondary fermentation, carried out by bacteria rather than yeast, that turns malic acid into lactic acid. It is carried out in most red wines and some white and sparkling wines. The main bacterium responsible is Oenococcus oeni, because it can survive the harsh conditions of wine: high alcohol, low pH and low nutrients. Malic acid is a stronger acid than lactic acid because it can dissociate in wine to give two protons rather than one. So after MLF the wine has less acidity overall and its pH rises. MLF is also a safety step: it is crucial to microbiologically stabilise most red wines, because it removes the malic acid that spoilage yeast and bacteria could otherwise feed on. Whether to use it often comes down to house style: producers who want fresh wines block MLF to retain bright acidity.

• Red wines: MLF is used in (almost) all red wines
• White wines: MLF works very well in most white wines, especially Chardonnay, Sauvignon Blanc and Pinot Gris, and can also be used in Riesling
• Buttery notes: bacteria produce diacetyl during MLF, and at low levels (1 to 4 mg/L) it can add 'buttery' or 'butterscotch' characters
• Acid drop: a wine starting with 2 g/L of malic acid would be expected to drop by 1.12 g/L of titratable acidity after MLF
• When is it done: a malic acid result of 0.1 g/L or less is low enough for MLF to be considered virtually complete

Two numbers describe a wine's acidity, and they are not the same thing. Titratable acidity (TA) is a measure of the acids in wine that can be neutralised with a base. pH is a measurement of acid strength (the concentration of free hydrogen ions). Tartaric acid is a stronger acid than malic acid, so two wines can have the same TA but different pH values. pH matters for stability: the higher the pH, the less sulfur dioxide (an extremely effective preservative for wine) is in its useful free form, and the less effective that free sulfur dioxide will be. Tartaric acid also causes the most common physical problem the AWRI's helpdesk sees in bottled wine: the precipitation of potassium bitartrate crystals, generally associated with inadequate cold stabilisation. Decreasing the temperature of the wine greatly enhances crystallisation, and steps to help prevent crystals forming after bottling are considered essential, particularly in white winemaking.

• Why crystals form: about half of the tartrate that is present and soluble in grape juice is insoluble in wine
• Testing: in the 'brine test', a filtered sample of wine is held at -4°C for three days and then checked for crystals
• Other tools: some winemakers use electrodialysis to remove potassium and tartrate ions, and crystallisation inhibitors such as carboxymethyl cellulose (CMC) and mannoproteins are also used
• Acetic acid bacteria: bacteria generally of the genus Acetobacter convert alcohol to acetic acid in the presence of oxygen, so spoilage problems occur only when wines are exposed to air

Winemakers rely on a few simple tests. Titratable acidity is one of the most common, simple and useful wine analyses, and its result is used in decisions including harvest timing, acid adjustments and cold stabilisation. TA is usually expressed in grams per litre of tartaric acid, but it is not a single acid measure: it is made up of contributions from tartaric, malic, succinic, lactic, acetic and citric acids. In the AWRI's survey, tartaric acid contributed between 30% and 45% of measured TA, so tartaric acid is only about half the story. TA most closely corresponds to the sensory perception of acid strength. Volatile acidity (VA) is measured separately by steam distillation, for example with a Cash still, with the result expressed as acetic acid equivalents.

• Titratable acidity (TA): expressed in g/L tartaric acid equivalents
• Volatile acidity (VA): the VA of a sound wine immediately after fermentation is usually in the range 0.1 to 0.4 g/L
• Legal limits: the OIV maximum acceptable limit is 20 milliequivalents per litre; the legal maximum in Australian wines is 1.5 g/L, expressed as acetic acid
• Malic acid monitoring: paper or thin layer chromatography, enzyme test kits and high performance liquid chromatography (HPLC) can all track MLF
• pH measurement: pH affects microbial stability, tartrate stability and the perception of wine structure

Primary sources (WSET, the Australian Wine Research Institute, the OIV, and university extension services at Oregon State, Washington State and Cornell): https://www.wsetglobal.com/knowledge-centre/blog/2026/understanding-acidity-in-wine, https://www.wsetglobal.com/knowledge-centre/blog/2021/december/14/what-is-wine, https://www.awri.com.au/wp-content/uploads/2011/07/Technical_Review_Issue_221_Wilkes.pdf, https://www.awri.com.au/wp-content/uploads/2011/06/Malolactic-fermentation.pdf, https://www.awri.com.au/industry_support/winemaking_resources/laboratory_methods/chemical/va/, https://www.awri.com.au/industry_support/winemaking_resources/sensory_assessment/recognition-of-wine-faults-and-taints/wine_faults/, https://www.awri.com.au/industry_support/winemaking_resources/storage-and-packaging/pre-packaging-preparation/cold-stabilisation/, https://www.awri.com.au/industry_support/winemaking_resources/laboratory_methods/chemical/malic_acid/, https://www.awri.com.au/industry_support/winemaking_resources/fining-stabilities/hazes_and_deposits/potassium_instability/, https://extension.oregonstate.edu/catalog/em-9583-preparing-harvest-grape-chemistry-prefermentation-adjustments, https://wine.wsu.edu/managing-high-acidity-in-grape-must-and-wine/, https://grapesandwine.cals.cornell.edu/extension/new-york-state-wine-analytical-laboratory/juice-analyses, https://www.awri.com.au/wp-content/uploads/2018/04/s1682.pdf, https://www.oiv.int/standards/compendium-of-international-methods-of-wine-and-must-analysis/annex-c/annex-c-maximum-acceptable-limits-of-various-substances/maximum-acceptable. Last verified 2026-10-05