Thursday, August 20, 2015


Hyperbolic as the President's claim to see and feel the half degree of  warming the globe has experienced in his lifetime may be,  he may indeed be able to taste it. 

A generation ago, the problem of alcohol in wine was largely one of  grapes insufficiently ripe, and alcohol levels too low. Traditional regulations tied designations of wine quality to alcohol levels - to be a “reserve”, a Rioja had to have a higher level of alcohol than a mere crianza, and to be reckoned Superiore, a Valpolicella needed more alcohol than a local vino di tavola. 

Today , as  climate change driven degree-day and sunshine creep  pack more sugar into grapes the world over, vintners face the antithesis of their old complaint. Average alcohol in Napa Valley Cabernet used to be in the 12% range. Today it is well over 14%, creating a disconcerting 'tropical' style- the Fruit Bomb.
At the time of the first great  German vintage I enjoyed, climate rarely allowed grapes there to yield 11 % alcohol, and delicate Moselles ran as low as 7.5 %. Thanks to warmer average conditions, most of the Riesling consumed in Germany today runs closer to 13%.  Meanwhile back in coastal California, Pinot Noir is beginning to present too much alcohol to technically qualify as table wine. Some I've just cellared makes ideal summer drinking because at 14.5%  it takes a hefty ice cube to bring a glass down to normal Burgundian strength !

The International Wine Review  recently examined :
the strategies and techniques used by winemakers in the vineyard and the winery to reduce excessive alcohol levels in wine. In excess, alcohol destroys the more delicate aromas and flavors in wine and undermines elegance and balance.
Today’s attempts to reduce alcohol in wine, and the controversy around some of the techniques, should be seen in context. Winemakers have long manipulated alcohol levels to achieve a particular, consistent style. Chaptalization—adding sugar to wine to increase alcohol levels—has been employed in Europe for centuries, resulting at times in violent protests1. Winemakers may also add alcohol to yield a strong, age-worthy wine. Port producers, for example, fortify red wine with brandy to raise alcohol, retain residual sugar, and yield a robust, long-lived wine. Conversely, Champagne producers purposely pick grapes with lower sugar (and potential alcohol) so that when the wine produced from them is put through secondary fermentation in the bottle, the increase in alcohol will not be so high as to make an inelegant, unbalanced sparkling wine. 

Reducing Alcohol Levels

Today’s winemaking toolkit allows a producer to control alcohol by using traditional means such as picking the grapes earlier with lower sugar levels or blending less strong wines with richer ones, or by employing highly technical and sophisticated means such as reverse osmosis. 

In the Vineyard 

Spinning Cone ColumnSpinning Cone Column
To control excessive alcohol potential in warmer areas and with global warming issues, alcohol management begins in the vineyard. Leaving a larger crop on the vine can slow down ripening, thus producing lower sugar in the grapes. Or, as has been shown at some properties in Napa [Dominus comes to mind], by decreasing the height of the canopy (and therefore fewer leaves), potential alcohol level was reduced by up to .75% in the wine. Viticultural techniques to slow vines down such as less vigorous rootstocks, later ripening clones, or a move to cooler areas, are key propositions for managing alcohol in today’s climate.

In the Winery 

Winemakers also have options for reducing alcohol in the winery. The simplest, if illegal in some places (not in California), is to dilute the must with water (Jesus juice). This works of course, but it also dilutes fruit extract and changes the acid balance in the wine. Blending less alcoholic wine into one more so is also a time-honored tradition; no need for fancy equipment! Blending is an extremely important tool, particularly for wineries that bottle large volume cuvées, where the penalty for high alcohol is very large. One example serves to demonstrate. Columbia Crest may bottle 200,000 cases of Grand Reserve Cabernet in a given vintage. If the wine’s blend remains below 14%, the approximate federal tax is about $578,000; if it is over 14% that figure rises to $780,000 plus!
Yet today’s wine market still has a “jones” for rich, fleshy, ripe and fruity wines. Getting those flavors in warmer areas like Napa Valley generally requires later harvesting, waiting for the phenolic maturation to catch up to more rapid sugar accumulation and high alcohols. In cooler places or vintages producers, as in Bordeaux for example, have a different problem; their wines need concentration due to lack of sufficient sugar/alcohol in the wine to balance. What’s a winemaker to do? Enter the machine--spinning cones, reverse osmosis, cross-flow filtration, and who knows what’s next! 
Spinning Cones. The Spinning Cone Column was developed in Australia by ConeTech. It consists of a vertical stainless steel cylinder that uses centrifugal force and vacuum to remove alcohol. Wine is fed into the top of the column and works its way down through a series of inverted cones, converting volatiles into a vapor stream, which is then condensed in a concentrated liquid form. This is followed by a second, higher temperature pass of the liquid through the cones to extract up to 1-2% alcohol. 
Reverse Osmosis. Reverse osmosis machines have been used in Bordeaux for at least four decades – larger chateaux like Leoville Las Cases used them for years to concentrate dilute musts by removing a percentage of water, concentrating the remaining juice. [However, with today’s warmer temperatures, the Chateau no longer needs to employ it.] Removing alcohol in a percentage of blend (often no more than 10% of the total amount of juice) and blending back in the low or no alcohol permeate to the whole, may be all that is necessary to make a balanced wine that is more expressive and harmonious.