Alcohol's affect on people is widely known, however it has a much greater purpose in a finished bottle of wine.
The body style or impression of fullness, the texture and volume of aroma are all affected by the percentage of alcohol in a given wine. Also, because alcohol content is listed on the label of every bottle, it is easy to learn volumes about any wine when purchasing for a social gathering or when pairing with food.
When yeast goes to work on grape sugars, called primary fermentation, alcohol is the main by product. Final alcohol levels are determined by how much sugar is in the grape, and therefore the overall impression of a finished bottle of wine.
Because warmer climates, such as those in California, encourage sweet and fully ripe grapes, primary fermentation brings about higher alcohol levels. Cooler climates, such as those in the classic wine growing regions of France, foster lower amounts of natural grape sugar.
In extreme circumstances, modern winemakers can alter a wine's final alcohol level. High alcohol wines can be tamed by sending them through a reverse-osmosis or spinning cone dealcoholization process. Chaptalization, or introducing beet or cane sugar during primary fermentation, will increase the alcohol content of a wine that might otherwise taste flimsy.
When alcohol levels are artificially manipulated, it is done to improve a wine's balance. A wine is considered to be in balance when its acid, tannin, sweetness and alcohol are seamlessly integrated.
High alcohol wines exhibit a voluptuous, glycerin-like impression in the mouth, along with a full body style such as in a modern Napa Valley cabernet sauvignon. This style of wine has become very popular in recent years, but winemakers are walking a fine line when reaching for this lovely texture. When a wine has a lot of alcohol in it, it offers a burning sensation in the nose and back of the throat and is called a "hot" wine. It's considered flawed as it is out of balance.
Conversely, a wine with low alcohol can sometimes seem thin and uninteresting. Because alcohol evaporates rapidly, it is the alcohol that carries a wine's aromas up the sides of a freshly swirled glass to the nose. If the wine lacks alcohol, such as in cheap jug wine, lower levels of aroma will be conveyed giving the impression that the wine is weak or even watery.
Because alcohol is directly related to the body style of a wine, knowing the alcohol content is essential when choosing a wine to pair with food. Try to match a full-bodied pot roast with a delicate chenin blanc and the food will obliterate the wine. However, pairing that same pot roast with a high alcohol Amador County zinfandel will result in a memorable culinary success.
As a general rule, wines with an alcohol content less than 13 percent are going to be lighter, while those reaching 15 percent or more are going to be hard pressed not to be considered hot. Use this rule of thumb to help select an appropriate bottle of wine for any occasion.