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Demystifying the world of wine

Why are alcohol levels in wine rising - climate, winemaker or consumer?

wine glasses splashed wine

Too much alcohol in wine?

Consumers and wine experts now expect not to be served thin, flabby wines with unripe tannins. To avoid these characteristics a wine needs alcohol. But if you're feeling a little too worse for wear after a night out, many wine drinkers are now concerned that alcohol levels have gone up too far - particularly from wines produced in hotter climates such as Australia.

Many top winemakers are of the view that wines with 15-16% alcohol are unbalanced and when drunk can produce a hot, burning sensation on the palate which can be unpleasant. 

Critically, someone drinking two 175ml glasses of wine with 10-12% alcohol would be likely to be under the legal drink drive in many countries but the same amount of wine with 14-16% alcohol could put you over the legal limit and facing serious trouble!

Why are alcohol levels in wine rising - climate or the consumer?

15% alcohol australian wine label

Alcohol levels in wine can range from as little as 5% for some dessert wines, e.g. Moscato d'Asti, to more than 20% for a port whose natural alcohol level has been increased by adding spirit. Two or three decades ago alcohol levels in wine were rarely more than 14%. Now is common to be drinking red wine at 15-16% especially from warmer climates like Australia, California and South Africa. 

Higher alcohol can mean higher risk of drink drive offences as well as nasty hangovers the next morning. 

An easy explanation could be global warming causing an increase in average temperature  and lower rainfall in the vineyard resulting in greater ripeness, more sugar in grapes and hence more alcohol during fermentation. But research has shown that the increase in average alcohol levels are much greater than could be explained by any change in climate.

AAWM logo

In a working paper published in May 2011 by the American Association of Wine Economists (AAWE),  alcohol levels for wines imported between 1992 and 2007 by the LCBO, the large and important liquor monopoly of Ontario that buys wines from all over the world, were analysed and compared with actual temperature increases in their regions of origin. 

"SPLENDIDE MENDAX: FALSE LABEL CLAIMS ABOUT HIGH AND RISING ALCOHOL CONTENT OF WINE by JM. Alston, KB Fuller, JT Lapsley et al"

It was concluded by the research team that "our findings lead us to think that the rise in alcohol content of wine is primarily man-made" with the main causes being "evolving consumer preferences and expert ratings" as more likely to have driven up alcohol levels. So wine producers have noted that experts and consumers desire and consume wines that taste "bigger" and in particular have softer tannins and lower acidity (acid levels fall as grapes ripen) and have deliberately chosen to have grapes picked later than they once were.

bad wine

To lessen the potential for super high alcohol wines when they are not desired, winemakers are choosing  lighter grape varieties, leaf removal, experimenting with pruning times and irrigation to reduce the time between sugar and phenolic ripeness. Phenolic ripeness (also referred to as physiological ripeness) refers to the changes in the tannins that occur in grape skins, seeds and stems. Sugar ripeness refers to the breakdown of acids and accumulation of sugars. In the classic northern hemisphere regions, grapes are typically harvested by sugar ripeness. Some producers are also employing biodynamic viticulture to increase flavour grapes are picked earlier.

Achieving more regularly greater phenolic ripeness is not just to achieve higher sugar levels and so higher potential alcohol levels, but also, crucially, riper and finer tannins. Winemakers choose the date of picking of the grapes based on tasting of the grapes and lab analysis of polyphenols and IPTs (total phenolics), which usually indicate the optimum phenolic ripeness a few days after sugar levels.

In the AAWE study, mean actual alcohol levels over 1992-2007 were highest in US, Argentine, Australian and Chilean wines (13.9, 13.8, 13.8 and 13.7% respectively). The average for New World countries analysed was 13.7%,  whilst the European average was 13.0% (with Spain highest at 13.4%).

In addition the researchers found an alarming difference between the alcohol information appearing on wine bottle labels and the actual alcohol levels as analysed by the Canadian LCBO. It was found by the researchers that labels "understate the true alcohol content by about 0.39% alcohol for Old World wine and about 0.45% for New World wine".

Average alcohol percentage for French wines analysed was 13.0% but wines produced in hotter areas such as the southern Rhône's Châteauneuf-du-Pape can have alcohol in excess of 15% and even 16%.

Star trek choking

Stated alcohol levels can be up to 1.5% less (or more) than the actual alcohol in wines up to 14% in the US where the tolerance for wines over 14% is still a full percentage point whereas wines sold in the EU have to be labelled with an alcohol percentage no more than 0.5% different from the actual level. The study found that the countries with the most notable understatements of the alcohol content were Chile, Argentina, Spain and the US.

One wonders if some unscrupulous winemakers with a wine of 15%, cheekily declares 13.5 or 14%.

Alcohol levels in wine and mis-labelling are a huge concern for many drinkers and an area where the industry and government must take a pragmatic but stringent view.