Reducing the alcohol content of wines has been getting more attention lately. As the temperatures in vineyards have been climbing around the globe, the grapes tend to be more ripe at harvest, and contain more sugar.
Yeast converts sugar into alcohol, so the more sugar, the higher potential alcohol. Where a range from 12.5 to 13.5 per cent alcohol content used to be normal for most dry wines, it is no trouble to find wines in the 15 per cent range today.
Winemakers are concerned about the balance of their wines, and sometimes the price implications of extra taxes charged on alcohol content. Consumers and health providers are concerned about too much alcohol and calories. So the de-alcoholization of wines has become more common, perhaps more than we may realize.
Two methods of reducing the alcohol content of wines are quite technical: reverse osmosis and spinning cone column. In reverse osmosis, a filter is used to separate water and alcohol molecules (and some acids) from the rest of the wine — the colour, flavour and tannin components. The water and alcohol mix is distilled to drive off some of the alcohol, and then this liquid is added back to the rest of the wine.
In the spinning cone column technique, wine under pressure enters the top of the column and spreads in a thin film over rotating vanes. Steam is pumped into the bottom and the lightest elements of the wine evaporate and are carried off with the steam. Adjustments of temperature and pressure can target specific molecular weights. For wine, it is a two-step process in which the first step is the capture of the lightest aromatic elements which are later added back into the wine. The second step removes some of the alcohol.
If you get the idea that these two methods involve considerable manipulation of the wine, I would have to agree. Does this affect the quality of the wine? That’s more of a debate. Some critics argue that it destroys any sense of terroir in a wine. But if all you want is a “nice affordable red,” then perhaps that isn’t much of a consideration.
There are more natural methods for reducing alcohol content. A simple, but usually illegal, method is simply watering down the wine. While this does have the desired effect, it does little to preserve the concentration of flavours and is almost certain to reduce the enjoyment of the product.
Stopping fermentation before all the sugar is consumed will also reduce the alcohol content, but will leave you with a sweet wine (meaning you have some calories from natural grape sugars). The wine is frozen to inactivate or kill the yeast and they are carefully filtered away to ensure fermentation does not restart.
Careful practices in the vineyard can also be effective in reducing sugar content while still allowing for ripe grapes. For example, reducing the ratio of leaf area to fruit reduces the sugar content of grapes, but does not affect the other elements of the ripening process. I think this is the approach most wine lovers would prefer, as it seems the least manipulative method.
I will have more on this topic in next week’s column.
This week’s wine is 19 Crimes from the Victoria region of Australia (NLC — $20.47). It is a blend of shiraz and durif, both of which originate in southern France. This wine is inky-dark and heavy with dark red and black bramble fruit flavours. It is heavy in the mouth as well, with just enough tannin, and demands a tasty red meat roast. Score: 15/Very Good.
Steve Delaney is a member of the Opimian Society. Email him at firstname.lastname@example.org