It is a common adage: the darker the beer, the higher the alcohol content, right? Well, according a several craft brewers, this is not necessarily so. According to these brewers, dark beers have been unjustly passed over, as the alcohol content of a beer is related to the beer's sugar content, while the beer's color is related to the color of the malt used during brewing.
Beer is brewed through a process called fermentation, in which yeast breaks down the sugar content of the malted barley, or malts, used. The by-product of this process is alcohol. As a result, the higher the sugar content of a beer, the less fermentation has occurred, and thus the less alcohol content present in the beer.
How beer color is determined
The color of the beer, however, is simply determined by the color of malts used. Each brew contains a variety of colors of malts; the ratio of these malts within the brew determines the beer's final color, while the color of the individual malts are determined by the level of roasting or caramelization they were exposed to before brewing. So a larger proportion of a more heavily roasted malt will yield a darker beer. Dark malts, however, typically only comprise about one to five percent of an overall brew.
Malt colors include light gold, which has been lightly roasted, light to medium brown, which have been moderately roasted, and very dark brown/black, which have been heavily roasted. Each level of roasting results in different notes and flavors present in the beer. As a result, mixing them will result in a complex, rich flavor. While dark roast malts may have some of the strongest flavor notes, such as coffee and chocolate, very little is typically added to the malt mix. Even small amounts of these dark malts, however, can dramatically alter the color of the final product in the same way that adding a small amount of dark paint to light paint will dramatically alter the paint's overall color.
Another common misconception about beer coloring is that darker beers are also higher in calories than light beers. The number of calories in a beer is a direct result of the amount of sugar in the beer. The amount of sugar is proportional to the amount of malt used in the brewing process, as malt, which is a source of the sugar maltose, adds to the overall sugar content of the beer. So if a recipe calls for more malt, then that beer, regardless of its color, will have more calories.
Considering all of this, the best way to be mindful of alcohol and/or caloric intake when enjoying a beer is to consult a bartender or nutritional facts label before ordering a beer, as there is no real way to know the specifics of a beer otherwise. But, if you have been hesitant about ordering a darker beer in the past for these reasons, maybe now is the time to try that stout or porter your bartender has been recommending! You never know, maybe you'll discover a new favorite.
Article sources
http://www.titletownbrewing.com/are-dark-beers-really-stronger-pale-beers
http://www.craftbeer.com/craft-beer-muses/the-lighter-side-of-dark-debunking-the-myths-surrounding-dark-beer
http://greatist.com/health/13-biggest-myths-alcohol
www.alcoholprofessor.com/blog/2015/02/17/exploring-6-popular-drinking-myths/