There are many reasons to enjoy drinking wine—it's great with food and it enables us to understand the history, geology, and culture of another location. But people like the way it tastes, too. However, did you ever wonder why one wine affected you differently from another, in terms of alcohol content? Different winemaking practices and processes may impact the final level of alcohol in any given wine. Certain methods of grape growing and wine production can affect how the alcohol content, how perceptible it is, and how it affects the flavor and balance of the final product.
The primary alcoholic compound found in wine is ethyl alcohol, or simply ethanol. It is a natural by-product of the fermentation process. When wine is made, yeast cells consume the available sugars in the grape juice and produce heat, carbon dioxide and, of course, ethanol in exchange. As yeast continues to multiply and consume the natural sugars, the alcohol levels in the wine will continue to rise, leading to a somewhat simple correlation: The more available sugars in grapes and grape juice, the more potential alcohol there is for the finished wine.
The measurable alcohol in wine is understood as a percentage of its volume, or alcohol by volume (ABV). This percentage must legally be included on every wine package, and will be found as a percentage number somewhere on the label. Typically, wine alcohol ranges from as low as 5 percent in some styles to as high as 20 percent in others.
You can generally assume that wines with a lower ABV are in general sweeter than those with a higher ABV. Although there are exceptions to this rule, the principle is generally the same: The lower the alcohol in a wine, the more residual and unfermented sugar remains; and the higher the alcohol, the less residual unfermented sugar remains. Wines with low ABV and high residual sugar are considered “sweet” and wines with higher ABV and no perceptible residual sugar are considered “dry.”
Alcohol levels may vary significantly from region to region, wine to wine, or grape variety to grape variety. The fuel for fermentation, sugar, is naturally produced in grapes, and the type of grape and where it grows both determine how much sugar is produced. The more ambient and available sunlight, the faster ripening happens, which means more sugars may be available for fermentation. Certain varieties are predisposed to warmer climates with more direct sun exposure, leading them to naturally produce more available sugars. The most common of these are Cabernet Sauvignon, Zinfandel, Malbec, Garnacha, Syrah, and several other varieties, though much of this is contingent on a vineyard’s particular location and the particular growing and harvesting practices employed on that site. As a general rule, however, white wines generally ripen faster but create fewer available sugars for fermentation, meaning most white wines reach dryness at around 11 to 14 percent ABV, though there are a few exceptions. Most red wines will typically reach dryness around 12 to 15 percent ABV.
Winemakers and their production methods also play a significant role in the ABV of their finished wines. Winemakers may intervene at several points during fermentation to add or subtract nutrients or sugars, and may employ either heat or cold to vessels to create the desired alcohol and other flavors in their wines. Wine harvest around the world typically takes place in the late fall, after the grapes have grown all summer and are ripe with available sugar. In traditional winemaking, fermentation will finish in one of two ways—when the yeast consumes all the available sugars in the wine, runs out of fuel, and dies; or if yeast hibernates because of cold conditions and sinks out of the solution to the bottom of the tank.
In modern winemaking, some of these naturally-occurring phenomena may be replicated by machinery, such as using glycol jackets on fermentation vessels to chill a wine and stop its fermentation before all the sugars have been consumed. This process is called cold-crashing or-cold shocking, and is frequently followed by racking and filtration to remove the hibernating yeast from the sweet, finished wine. Wines typical of this style are Riesling, Moscato, and some Chenin Blanc.
What's a Fortified Wine?
There are other classic and antique methods of halting fermentation before yeast has consumed all the available sugars as well. The most common technique is called fortification, and it involves adding a distilled neutral grape spirit, or brandy, to a still-fermenting wine. Although yeast excretes alcohol as it consumes sugar, in high enough concentrations, the very alcohol yeast produces is toxic to its survival. Too much alcohol, and the yeast “suffocate.”
When this potent distilled alcohol is added to a fermenting wine, the yeast die, leaving behind wine that's still sweet but with a higher alcohol content. These wines, now stronger in alcohol, are fortified. Initially, this was a method to store wine longer for shipping; alcohol is a natural preservative. Sherry, Madeira, and Port are all common fortified wines, available in varying styles and with their own eccentricities of production.
Trendy High Alcohol Wines
In recent decades, the popular trend in winemaking has been to create wines of a unique profile that contain exceedingly high levels of alcohol, some remaining residual sugar, and somewhat low acid and low tannin profiles. This phenomenon took off around 2001 in and around Napa, California, when a vigorous yield provided more ripe fruit than the wineries could typically handle. This meant that there were more available sugars in the grapes, but fewer of the other components such as acid or tannin, which break down after peak ripeness is achieved. The resulting wines were big, boozy, somewhat sweet, and available to consumers more quickly.
They received glowing accolades and press, namely from one noted publication, Robert Parker’s Wine Advocate, which introduced the 1-100 point score system to American consumers several years earlier. Today, some wineries specialize in producing this specific style in a quest to please the international consumer palate and to chase these highly sought after scores.
How to Serve High and Low Alcohol Wines
When it comes to pairing wines with varying amounts of alcohol, it’s key to understand how alcohol affects the palate. Higher levels of alcohol provide more body, or viscosity to wine; however, copious levels of alcohol can also dull or numb the taste buds, making high alcohol wines a generally poor choice for food pairing. Higher alcohol can also correspond to warmer sensations in the throat and body, making it a poor choice for spicy foods. When serving an array of wines with differing levels of alcohol, the general guidance is to serve the high acid, lower alcohol wines first followed by increasing levels of alcohol. When serving fortified wines or high alcohol table wines are being served, a great option is to serve them alongside an assortment of cheese, crackers, and charcuterie to refresh and revive the palate.