Published by Sally on November 18, 2009
1 Comment

A version of this article first appeared in Wine and Spirit in 2006, since merged into Harpers Wine and Spirit.

Like the old Opal Fruits (Starburst for younger readers), acidity is ‘made to make your mouth water’.  It’s responsible for the refreshing sensation of wine, think zesty, grapefruit, guava and grassy New Zealand sauvignon blanc.

Getting the acidity level right in wine is serious business, but it is not something that can be considered in isolation, it needs to be balanced with other components, fruit, sugar, tannin and alcohol.

Riesling and cabernet sauvignon are ‘high acid’ varieties, whereas gewürztraminer and grenache are ‘low acid’

Individual grape varieties have their own inherent acidity levels, for example, riesling and cabernet sauvignon are ‘high acid’ varieties, whereas gewürztraminer and grenache are ‘low acid’. In an ideal climate, which varies for each grape variety (plus other factors such as yield, vine age etc), all components will be in balance in the grape and subsequently in the wine.

From a peak at the beginning of grape ripening, acidity decreases in a heat-related process.  In  hot climates, acidity levels can fall quickly, and in cool climates, without sufficient heat, acidity levels can remain searingly high. A challenge is that sugars and fruit flavours accumulate during ripening, so harvest is always a tightrope walk between falling acidity and increasing sugars and fruit flavour, as well as ripening tannins.   The Bordeaux right bank trend among some Châteaux is to leave the grapes on the vine longer, picking later for fuller, sweeter fruit, with the inevitable consequence of lower acidity.  But if acidity becomes too low a wine tastes flabby, fat and forlorn.

Winemakers can adjust acidity during winemaking to try to reach the perfect point of balance.  Adding acidity is common in hot climates such as the Central Valley in Chile or the USA, and inland regions of Australia. Much less widespread is the process of de-acidification which can be done in cool climates such as UK, northern Germany or Tasmania. An alternative here is to add sugar before fermentation as a potential balance-restorative process.

As well as imparting freshness and fruitiness to wines, high acidity protects wine against attack from bacteria.  For these anti-microbial properties, and because the acidity becomes better integrated, it is best practice to add acid before fermentation, firstly by dissolving the acid crystals it in a little grape juice. It is usual to add tartaric acid, which is the most common naturally-occurring one in grapes, in amounts ranging from 1 to 4 grams per litre.

Can you taste added acidity? If the wine is balanced, without any of its component parts sticking out, and if the integrity of a grape variety’s natural acidity levels and varietal expression are not compromised, does it really matter?


One Response to “Acidity”

  1. Carol Lerner Says:

    Trying to locate low acid wines to reduce irritable bowel syndrome. Please advise specidic brand names of low acid wines. It needs to be brought out for public knowledge of so many people having this problem.

    thank you in advance for your response

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