Acidity Types in Wine

Acids are what make your wine taste refreshing. WSET explains that their presence makes your mouth water, and that they can also play a role in protecting the wine from spoilage. Wine does not contain just one acid but several. The AWRI (Australian Wine Research Institute) sorts them 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. WSET names tartaric and malic acid as 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. WSET puts total acidity in most wines in the range of 5.5 to 8.5 g/L (grams per litre).

• Tartaric acid: from the grape; WSET notes that all wines contain tartaric acid from the grape juice
• Malic acid: from the grape; the Oregon State University Extension Service names malic and tartaric as the major acids in grapes
• Citric acid: from the grape, but the AWRI says it is only present in very small quantities (if at all)
• Lactic acid: made by bacteria from malic acid; WSET notes that all reds and many whites feature lactic acid
• Succinic and acetic acids: formed through yeast and bacterial activity, per the AWRI

WSET notes that tartaric and lactic acids are odourless, and that 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, WSET says, 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. WSET also notes that 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, and the AWRI describes volatile acidity as generally perceived as the odour of vinegar.

• Flavour clues in whites: per WSET, 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: per WSET, 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: WSET describes malic acid as sharper and lactic acid as softer
• Acetic: the AWRI reports an aroma threshold in wine as low as 0.1 to 0.125 g/L, and says the level regarded as detrimental is usually greater than 0.7 g/L
• Sweetness masks acidity: WSET notes that a wine with high residual sugar can taste balanced even when its acidity is very high, but acidity will still make your mouth water

WSET calls climate 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. WSET adds that the same is true of warmer vintages, and that 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 WSET gives. 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, per WSET
• Warm climates: per WSET, warmer climates often produce wines with lower acidity, but high altitude and cool night temperatures can preserve freshness
• Vintage variation: the AWRI notes that malic acid is affected by the growing conditions experienced by the grape

Malolactic fermentation (MLF) is a second fermentation, carried out by bacteria rather than yeast, that turns malic acid into lactic acid. The AWRI describes it as a secondary bacterial fermentation 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: the AWRI calls it 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, per WSET: producers who want fresh wines block MLF to retain bright acidity.

• Red wines: Washington State University says MLF is used in (almost) all red wines
• White wines: Washington State University says MLF works very well in most white wines, especially Chardonnay, Sauvignon Blanc and Pinot Gris, and can also be used in Riesling
• Buttery notes: the AWRI says bacteria produce diacetyl during MLF, which at low levels (1 to 4 mg/L) can add 'buttery' or 'butterscotch' characters
• Acid drop: the AWRI gives the example that 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: the AWRI says 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), per Cornell University's wine laboratory, is a measure of the acids in wine that can be neutralised with a base. pH, per the Oregon State University Extension Service, is a measurement of acid strength (the concentration of free hydrogen ions). The Oregon State University Extension Service explains that 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 AWRI notes that the higher the pH, the less sulfur dioxide (which the AWRI calls 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, which the AWRI generally associates with inadequate cold stabilisation. The AWRI explains that decreasing the temperature of the wine greatly enhances crystallisation, and it considers steps to help prevent crystals forming after bottling essential, particularly in white winemaking.

• Why crystals form: per the AWRI, about half of the tartrate that is present and soluble in grape juice is insoluble in wine
• Testing: the AWRI recommends a 'brine test' in which a filtered sample of wine is held at -4°C for three days and then checked for crystals
• Other tools: the AWRI notes that some winemakers use electrodialysis to remove potassium and tartrate ions, and that crystallisation inhibitors such as carboxymethyl cellulose (CMC) and mannoproteins are also used
• Acetic acid bacteria: per the AWRI, 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. According to the AWRI, 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 the AWRI stresses that 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, and the AWRI concludes that tartaric acid is only about half the story. Cornell University's wine laboratory notes that TA most closely corresponds to the sensory perception of acid strength. Volatile acidity (VA) is measured separately: the AWRI describes 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, per Cornell
• Volatile acidity (VA): the AWRI says 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 AWRI gives the legal maximum in Australian wines as 1.5 g/L, expressed as acetic acid
• Malic acid monitoring: the AWRI lists paper or thin layer chromatography, enzyme test kits and high performance liquid chromatography (HPLC) as ways to track MLF
• pH measurement: Cornell notes that 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 2026-09-28