Part one of this blog gave us some background on high Brix grapes, musts and the resulting high alcohol wine. The easiest (but not always legal) way to counter the effects of a potential high alcohol ferment is to add water to the must. This is usually done prior to fermentation. In warmer viticultural countries, winemakers often employ this technique to dilute musts from grape varieties that are harvested at 27 to 30ºB or higher! The arguments against this moist method are quite watered down by now, but the critics have a valid point. For instance, when you add sugar to wine (chaptalization, as it is called in France), you mainly alter the production of alcohol in the finished wine. However, the addition of water dilutes and impacts an innumerable amount of aroma, tannic and other chemical constituents. So there are obviously two sides to this rather soggy debate.
In California, the addition of water may only be done to prevent a stuck fermentation. Section 17010(a) of the California Administrative Code states: “…and no water in excess of the minimum amount necessary to facilitate normal fermentation may be used in the production or cellar treatment of any grape wine…”. In the less liberal South Africa, the addition of water to must is still in breach of EU wine law and in all probability will still be illegal for quite some time. Some producers (notably in California) take watering back a further step. After bleeding off some of the juice (saignée), water is added to the tank. The initial step drastically alters the juice to skin ratio and decreases the amount of sugar in the must. The watering back further dilutes the sugar concentration. I have heard (and don’t have the hard facts) that another method to eventually reduce alcohol is applied in Australia. It is legal to add water that has been removed from juice via reverse osmosis to other juice or wine seeing that it originates from grapes and not the “black snake.”
Winemakers all over the world are probably most comfortable with reverse osmosis to remove access alcohol in finished wine. Portable units are available that can be used to treat your high alcohol wine and thus effect a significant decrease in alcohol concentration. Another technique is the spinning cone technique, which fractionates wine. After alcohol is removed, the desired volatile components are simply added back to the wine. The downside to these techniques is that important aroma compounds and mouthfeel can be lost. As a winemaker once elegantly put it after treating a high alcohol wine with reverse osmosis: “The alcohol level is acceptable, but now we’re stuck with a bland, soulless wine.”
The winemaker will ultimately decide how the alcohol issue should be remedied. To those that believe that no superior winemaker has ever added water to wine, I guess the American Army policy of “Don’t ask, don’t tell” (Google it if you don’t know what I’m talking about) will be interesting and enlightening reading.
Bernard Mocke is a technical consultant for Anchor Wine Yeast.