Wine and the impacts of high alcohol levels

On the Grapevine , Feb 2013

By Bro Mike, Wine Correspondent

Wine can get you drunk or at least very merry because wine is an alcoholic drink. This sounds like a rather obvious statement, but it’s something we can forget when discussing the finer aspects of wine. It’s part of the point of wine, that’s why it’s the social drug of choice in most western countries.

Not too long ago, the level of alcohol in most wine hovered around the 11 to 12% range. These days it's not uncommon to see wines of 14 or 15% alcohol. Some wine drinkers love the big, full-bodied, high octane wines that are found so easily now. Many consumers even see high alcohol as an indication of quality. Others are more conscious of their alcohol consumption and prefer wines of more moderate alcohol, but they're finding it increasingly harder to find bottles with an alcohol level around 12%.

Alcohol levels are on the rise

Australian studies have shown that alcohol levels in wine from the early 1980s to the mid 2000s consistently increased in alcohol levels, especially in red wines, with levels rising from 12.5% to over 14% with some averaging 15%. This is not just an Australian trend. Recent Bordeaux vintages also illustrates this trend with many are showing alcohol levels of 14%, and some being even higher.

Some wine critics reject high alcohol wines as being clumsy, dull, and unbalanced, and yet these same wines consistently receive high scores by many wine experts and during blind tastings. Many other critics and winemakers say the level of alcohol shouldn't matter as long as the wine is balanced.

It is undoubtedly a combination of many factors that has led to the rising levels of alcohol in wine. Climate change, improved vineyard practices, and consumer preference are a few of the main causes.

Climate change

It's no secret that grapes grown in warmer climates ripen with higher sugar levels than those in cooler climates, thereby producing higher alcohol wines. Many warmer regions such as California, Australia, and parts of Chile, have struggled with very high alcohol levels for some time. The trend now seems to be taking hold in cooler wine regions as global warming has had a major effect on temperatures.

Over the past several decades, average temperatures have risen noticeably. Prior to the late 1980s, in Bordeaux, 40% of the vintages were unable to ripen Cabernet Sauvignon sufficiently, often resulting in green tasting, harsh wines. Since 1988, every single vintage has had temperatures high enough to successfully ripen the grapes. Similar occurrences have happened in many other wine regions.

Improved vineyard practices

Many quality grape growers and winemakers have employed new and improved viticultural practices that enable them to harvest riper grapes than ever before. Leaf thinning involves plucking leaves from around grape bunches, which allows the sun to shine directly onto the grapes, ripening them more fully than if they were shaded by leaves. Picking extra bunches of grapes off the vines before they have the chance to ripen, allows the vine to concentrate more energy on ripening the remaining bunches. A longer hang-time simply means that grapes are left on the vine for a longer period before they are harvested. This allows the grapes to accumulate higher levels of sugar. The higher the amount of sugar in the grapes the higher the potential alcohol level in the finished wine.

Consumer preference

Consumers' tastes also appear to have changed in the past couple of decades. Many wine drinkers are now looking for riper, richer wines that are more approachable at a younger age. Influential wine critics, especially in the United States, frequently give high scores to the huge, high alcohol blockbusters, which drive up the purchases of those wines. People are under the impression that those are higher quality wines. Some wine professionals are concerned that an 'international style' of wine is the result with wines tasting similar no matter where they come from.

Effect of high alcohol on wine

Alcohol is important to the sensory properties of wine and if a wine has too much alcohol, it can be detected when simply smelling the wine when it can be perceived as a burning in the nostrils. On the palate, the alcohol can overpower other properties, such as fruit, and feel hot in the throat. It can also add bitterness and a perception of sweetness to the wine.

Some say that no fine wine can be made with alcohol levels over 14% and others say it's impossible to put a number to acceptable alcohol levels. In order to create a 'balanced' wine, every component in the wine - acid, tannin, fruit, sugar, and alcohol - should work in harmony with each other. When one component, including alcohol, stands out above the rest, the wine is not in balance and this effects the quality and the ability of the wine to age gracefully.

Many great Australian wines, particularly our prized shiraz from South Australia and central Victoria are above 14 % but still in harmony, whereas in Western Australia many of their premium reds are below 14%, possibly reflecting the milder maritime climate.

Effects of high alcohol wine on consumers health

The Australian Guidelines on drinking alcohol defines a standard drink as any drink containing 10 grams of alcohol. For red wine at 13.5 % alc. vol a 100 ml standard serve equals 1 standard drink and a 150 ml average restaurant serving equal 1.5 standard drinks The guidelines recommend, for men: no more than 4 standard drinks a day on average and no more than 6 standard drinks on any one day, with one or two alcohol-free days per week. For women: no more than 2 standard drinks a day on average and no more than 4 standard drinks on any one day, with one or two alcohol-free days per week. Therefore the recommended moderate daily intake of wine from a health perspective, based on wines of moderate alcohol level, is about 2-3 glasses (150 ml) of wine a day for men and 1-2 glasses a day for women.

Obviously, if a higher alcohol wine (say above14 .5 % alc vol) is being enjoyed, then the amount of wine consumed needs to be adjusted to a lower amount (smaller amounts in each glass) in order to avoid the risks associated with heavier alcohol intake.

What can be done about it?

There are three approaches to deal with higher must sugar levels, leading potentially to higher alcohol in the final wine.

· In the winery by alcohol reduction. Modern reverse osmosis equipment can remove as much alcohol as you wish, but it needs a skilled operator and savvy winemaker/taster. A process such as this is fixing a problem and it's obviously better that the problem isn't created in the first place. Moreover, it is anathema to the natural wine brigade.

· In the vineyard by viticultural interventions and decision-making. There are numerous ways to deal with the problem at source in the vineyard. The most simple way to reduce alcohol levels is to pick the grapes earlier. A holistic approach to vine health, retention of acidity and picking over a period of time at different alcohol levels. Factors such as row spacing, vine density, pruning decisions, vine canopy and fruit shading influence a vines physiology when it comes to ripening the crop. With whites, such as chardonnay, vine management has led to the adoption of earlier picking, while maximising fresh fruit flavours and lower alcohol levels.

· Future yeast development. Yeasts produce alcohol from metabolizing sugar. If by selective breeding or genetic modification we can get yeasts to use a different metabolic pathway, one that, for example metabolizes sugar to glycerol, then the yield of alcohol per gram of sugar will be less. There are currently a number of projects looking at this possibility, and it may well be that in five years time yeasts will be on the market with a lower conversion factor. But this is currently some way from being a practical option.


If you are going to intervene, the earlier you intervene in the winegrowing process the better. Of the solutions to high alcohol outlined, the most promising is the set of vineyard interventions that may well help in producing fully ripe grapes at lower sugar levels with well balanced acidity and fruit flavours.

If you enjoy the bigger alcohol style wines just remember to reduce the serving size a little. Wine is a great food and social accompaniment when enjoyed in moderation.