“Would it be possible for you to include the alcohol content of the various wines that you review?” wrote William Byxbee of Charles Town, W.Va. “I have noticed over the years a definite trend towards increased percentages of alcohol, especially in some whites and rosés that typically were low in alcohol and thus refreshing and drinkable. Now I see some in the 13-14.5 percent range. If you include this detail, I’m sure you will be giving your readers more options as they decide what wines to try.”

Laments about “alcohol creep” are increasingly common. The phenomenon has been apparent in the past 20 years, especially in New World wines. Several factors are credited or blamed for the trend, depending on your perspective.

Improved vineyard techniques enable vintners to ripen grapes more consistently to higher sugar levels. Commercial yeasts are more efficient at converting grape sugar to alcohol. Indicators of ripeness and when to harvest have expanded from mere sugar levels to include the suppleness of the grape skins and the color of the stems and seeds; both of those factors are ideal only at higher sugar (and therefore alcohol) levels. Global warming might even contribute. Wine critics have been blamed for awarding high scores to more powerful, riper wines. And those wines have been popular. Alcohol starts as sugar, after all, and lends an impression of sweetness to the finished wine. We Americans are notorious for our sweet tooth.

This is not an insignificant trend. Simple math tells us a wine with 15 percent alcohol is 25 percent stronger than a 12 percent wine. That can add up over the course of an evening.

Readers of this column know that I advocate a more elegant, restrained style of wine with moderate alcohol. Some blockbuster wines can work, but those are rare and not easily imitated. All too often, the alcohol skews the wine off-balance and leaves a “hot” impression on the palate.

Even so, I have been hesitant about including alcohol levels in my reviews for two reasons.

First, I want to encourage you to try various wines outside your comfort zone. I don’t want to give you excuses to judge them before you try them.

Second, the alcohol level stated on a wine label isn’t necessarily accurate, a byproduct of federal regulations that have less to do with how we drink than with taxation. Wines between 7 percent and 14 percent alcohol are considered table wines, taxed at $1.07 per gallon, or about 21 cents per standard 750-milliliter bottle. However, there is a 1.5-percentage-point leeway, provided the wine doesn’t exceed 14 percent — meaning a wine labeled 12.5 percent could be as high as 14 percent.

Wines at 14.1 percent or higher are considered dessert wines and taxed at $1.57 a gallon, or 31 cents per bottle. (There are other tax categories for wines and spirits over 21 percent alcohol, and all sparkling wines are taxed at $3.40 a gallon, or 67 cents per bottle.) For levels over 14 percent, wineries have a labeling leeway of 1 percentage point, meaning that your 16 percent zinfandel could clock in at anywhere between 15 percent and 17 percent.

“The alcohol range leeway allows the government to decrease the number of labels submitted for approval and lowers the regulatory burden on small wineries,” says Michael Kaiser, communications director for WineAmerica, a national winery trade association. He gave the hypothetical example of a Virginia cabernet franc that attains 13.4 percent in 2010 but only 12.6 percent in 2011; the winery would not have to submit a new label for federal approval simply because of that change.

The flexibility in the regulations helps wineries deal with the vagaries of vintage variation, as long as alcohol levels stay within a certain range from year to year. But from a truth-in-labeling standpoint, the alcohol level on the label is less helpful to us consumers. Even so, beginning this week I will include the label’s alcohol content in my reviews. Think of it as an indicator of style, not quality. And please don’t use it to calculate your blood alcohol level.

McIntyre blogs at dmwineline.com. On Twitter: @dmwine.

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