Chris Shanahan: Alcohol and wine flavour

‘Although alcohol does not have a taste’, writes Professor A. Dinsmoor Webb (Oenologist, UC Davis, retired), ‘it has an effect, not just on the human nervous system, but on how a wine tastes. The alcohol content in a perfectly balanced wine should be unfathomable, but wines that are slightly too high in alcohol can have a hot aftertaste. As a general rule, wines described as ‘full bodied’ are high in alcohol, while those described as ‘light’ are low in alcohol.’

Professor Webb’s words imply that there’s an optimum alcohol content for each wine. Indeed, over the last few years, many Australian wines, reds in particular, have copped criticism for going over the top.
And last week at the Australian Wine Industry Outlook Conference, Dan Jago, director of beer, wine and spirits for giant UK retailer, Tesco, warned Aussie makers of a swing towards lighter red styles.

It’s a topic widely discussed amongst winemakers, partly in response to perceived consumer resistance to reds weighing in at fifteen per cent or more alcohol by volume. The alcohol is quite often accompanied by masses of sweet fruit, mountains of tannin and enough oak to rebuild the ark.

The issue is not limited to reds, nor solely to Aussie wines. I once tasted, for instance, a sherry-like Californian chardonnay bottled at a breathalyser blowing 16.5 per cent alcohol. It was awful.

And it’s not only consumers driving the alcohol discussion. Many winemakers and wine show judges question the drinkability of excessively big wines. A couple of years back, for example, Jim Brayne, McWilliams chief winemaker told me, ‘The wheel seems to be turning. High quality shiraz and chardonnay seems to be coming down in alcohol as winemakers seek finesse and palate structure rather than just volume’. ‘Wine judges are rewarding the finer wines, too’, he added.

To understand the relationship between flavour and sugar (and, hence, alcohol), it’s worth looking at wine grapes through a vigneron’s eyes. The vigneron approaches grapes with a wine style in mind. Two of the key parameters in deciding when to harvest grapes to achieve the desired style are sugar ripeness and flavour ripeness. These are related but not in a linear way.

Now, sugar ripeness determines the alcohol content of a dry wine and in most Australian growing regions achieving sufficient sugar levels is not a problem. However, as winemakers tend to harvest for a particular flavour profile, it’s not uncommon, especially in warmer areas, for sugar levels (and therefore alcohol potential) to climb very high before flavour ripeness is achieved.

So, let’s look at the Hunter examples. Jim Brayne says that semillon in the lower Hunter develops ripe fruit flavours when the alcohol potential is around ten to eleven per cent. Indeed, the better Hunter semillons today continue to be made at about this level. In contrast, says Jim, semillon grown in the much warmer Griffith area, develops ripe fruit flavours at much higher sugar levels and therefore the wines are more alcoholic

Now, with Hunter shiraz, things have changed. Jim says that in the old days the Hunter’s lousy vintage weather often left shiraz stranded on about 11 per cent alcohol. These wines were light, thin and green. Improved viticulture, says Jim, means that even in poor seasons today’s Hunter shiraz reaches respectable sugar and flavour ripeness levels.

Some makers, however, boost alcohol in poor seasons by running off juice, concentrating it by removing water, then adding the concentrated juice back for fermentation.

Interestingly, in good seasons, sugar levels achieved in the Hunter shiraz today are similar to those achieved in good seasons in the old days.

While there is evidence that some modern yeasts extract more alcohol than older strains, it seems the ultimate alcohol content of any given wine is dependent on the grape variety, the region, the season and winemaker decisions about time of harvest.

If, indeed, we experience a wider swing to elegance and finesse, we’ll see subtle declines in alcohol content because winemaker in any given region still have to harvest within the fairly narrow flavour ripeness spectrum. I don’t think we’ll see again, for example, the thin, green 11 per cent alcohol Coonawarras peddled about in the early eighties.

For those seeking elegant, comparatively low alcohol wines, the answer may be found in cool areas, or in regions where through some peculiarity or another, a particular variety (like Hunter semillon or Clare riesling) achieve flavour ripeness before the sugar level explodes.

That said, wines of comparatively high alcohol content are not unique to Australia and can be just as easily found in France, Italy, Spain or pretty well anywhere you look. Whether nature provides or humans add the sugar that ultimately becomes alcohol matters less than the impact that the alcohol has on a wine’s flavour.

As the good professor said above ‘the alcohol content in a perfectly balanced wine should be unfathomable.’ I’ve had beautifully balanced, elegant, Aussie reds weighing in at 15 per cent alcohol and hot, hollow ones of only 13 to 14 per cent.

What that means, of course, is that alcohol content on its own tells you little about the overall quality of a wine. And given our growing export success it suggests that in working towards lower alcohol content, we shouldn’t sacrifice the ripe, fruity flavours that people love.