Every successful band has an unsung hero. These artists rarely seize the limelight, but they’re always working hard behind the scenes, and they’re instrumental to the band’s sound.
Examples include Rolling Stones co-founder Ian Stewart, Pink Floyd guitarist Richard Wright and Malcolm Young of AC/DC. They never received the public acclaim given to the likes of Mick Jagger and Keith Richards, but they’re the glue that held their bands together.
Acidity plays a similar role in wine. The other key characteristics - alcohol, body, sweetness and tannin - get all the attention, whereas acidity rarely enjoys the credit it deserves. Its work is more subtle, but it’s just as important in shaping how a wine feels, tastes and ages.
Many people overlook acidity, and others misunderstand it, confusing it with bitterness or high levels of alcohol. Truly understanding acidity in wine will make you a better taster, so we’ve explained how it works and why it matters.
Why acidity matters in wine
Acidity balances the flavours in wine, and it ensures that no single component overwhelms your palate. It also provides a refreshing mouthfeel, which stops wine from tasting flat or flabby. Acids act as natural preservatives too, allowing fine wines to age beautifully for a decade or more.
Have you ever squeezed a wedge of lemon onto a piece of grilled fish? The impact is drastic: it sharpens the flavours, cuts through the oil, tenderises the meat and ultimately lifts the dish.
Acidity plays a similar role in wine. It’s what gives a wine its freshness and definition, that quality that makes you want to go back for another sip. When it’s too low, a wine becomes soft and shapeless.
Acidity plays an important role in every style. In sweet wines, acidity is the counterweight that stops sugar from becoming cloying. In sparkling wines, it’s the taut backbone behind those fine bubbles. If you’re tasting a red wine that’s matured gracefully for decades, acidity allowed it to retain its freshness long after the fruit had softened.
How to assess wine acidity
All wines contain tartaric acids from the grape juice. All reds and many whites also feature lactic acid, which is converted from malic acid.
These acids are odourless, so how do you assess acidity in wine?
Here’s the good news: you don’t need any special equipment. Acidity is assessed on the palate, and your mouth does the job remarkably well.
Take a sip and pay attention to what happens next. For most people, acidity creates a sharp, tingling sensation, which is detected most strongly at the sides of the tongue.
However, the real giveaway is in your saliva. The more your mouth waters, and the longer it waters, the higher the level of acidity in the wine.
If there’s little salivation and the wine feels soft and rounded, it’s likely that you’re tasting a wine with low acidity. By contrast, if your mouth starts to water quickly, and the effect lingers, you’re tasting a wine with higher acidity. That’s your mouth trying to restore its natural balance.
Here’s a practical tip: make sure you’ve drunk plenty of water before tasting. If you’re dehydrated, your salivation response will be suppressed, and you may then underestimate acidity.
Which taste and contextual clues can indicate higher acidity?
Certain flavours are often associated with higher levels of acidity. They serve as useful clues when you’re trying to work out a wine’s acid profile.
If you’re picking up notes of lemon, lime, grapefruit or green apple when tasting a white wine, it’s likely to have a strong acidic backbone. Sauvignon Blanc, Riesling, Chenin Blanc and Albariño often have high acidity. Meanwhile, Viognier and Gewürztraminer are often softer and more voluptuous.
When it comes to red wines, notes of bright red fruit like cherries and cranberries can indicate higher acidity. Varieties like cool-climate Pinot Noir, Sangiovese, Nebbiolo and Gamay often benefit from high levels of acidity.
Context matters too. Wines from cooler climates tend to retain more of their natural acidity, as the grapes ripen more slowly in those regions. Chablis and the Mosel are classic examples. Both regions are renowned for yielding wines with pronounced acidity and freshness.
Warmer climates often produce wines with lower levels of acidity, but high altitude and cool night temperatures can preserve their freshness.
What affects acidity in wine?
Climate is the single biggest influence on a wine’s acidity. Wines tend to hold onto more of their tartaric and malic acid when they come from cooler regions.
As temperatures rise during the ripening period, the vine metabolises the malic acid. This can cause warmer regions to produce wines with lower acidity. The same is true of warmer vintages. It’s also worth noting that grapes picked earlier in the season should retain more acid, whereas those left on the vine for longer will retain less.
Winemakers also play a key role in shaping acidity. They can use malolactic fermentation to convert sharper malic acid into softer lactic acid. This creates a rounder, creamier wine. It often comes down to house style. If producers want to create fresh wines, they block malolactic fermentation to retain that bright acidity.
Producers can also adjust the acidity. In warmer regions, they may add tartaric acid in powder form if the grape acid fell too far during ripening. Meanwhile, winemakers in cooler regions can add an alkaline substance to neutralise excess acid if the levels didn’t fall sufficiently during the ripening period.
Factors that can mask or alter perceived acidity
Acidity doesn’t always make a grand entrance onto the stage, and it can be overshadowed by the other ‘band members’. The most common culprit is sweetness.
A wine with high residual sugar can taste balanced and poised even when its acidity is very high. Think of a well-made Sauternes, which is searingly acidic, but comes across as luscious rather than sharp. That’s because the sugar and acid are working in harmony together. Taste a bone-dry Chablis with a comparable acid level and the acidity will feel far more prominent, simply because there’s nothing to temper it.
This is precisely where the aforementioned salivation test earns its stripes. Regardless of how sweet a wine is, acidity will still make your mouth water. That response doesn’t lie.
Alcohol can also impact your perception of a wine’s acidity. Some high alcohol wines can create a burning warmth, which may feel a little like acidity. The distinction? Alcohol produces heat, whereas acidity produces salivation, so focus on which one you’re experiencing.
The wine’s serving temperature also matters. If you’re presented with a wine that’s too warm, it can seem flat and lacking in freshness. If the bottle is chilled a little, it can display its acidity with far greater clarity.
Acidity in practice
Let’s say you taste a cool-climate Chablis alongside a warm-climate, oak-aged Chardonnay. The Chablis should show pronounced acidity, with bright citrus flavours and a long, mouth-watering finish. The oak-aged Chardonnay, which has been shaped by malolactic fermentation and time in the barrel, should feel rounder, softer, more buttery and gentler on the palate. It’s the same grape, but a completely different experience, and that’s largely down to acidity.
German Riesling takes the lesson further. If you sip a bone-dry Trocken Riesling from the Mosel, you’re likely to experience bracing acidity, which can be exhilarating. Meanwhile, a sweeter Spätlese from the same region could have a similar level of acidity, but the residual sugar will completely change your perception of it, as it provides a delicate balance of richness and freshness.
The bigger picture
Acidity may not always be the most obvious characteristic you notice when tasting wine, but it’s one of the most important. It will shape the balance and freshness of the wine, and it will play a major role in helping the wine pair with foods.
The good news is that assessing acidity in wine is more straightforward than you might think. Make sure you’re well-hydrated, sip the wine, and consider how much your mouth waters and for how long. Focus on what can influence acidity and what can mask it, and you’ll soon be able to quickly detect a wine’s acidity levels.
About the author
Martin Green is an experienced writer who has covered the wine trade since 2012. He was previously the editor of Drinks International and Drinks Retailing, and he also writes regular articles for Decanter.
