Over the last weekend I had some friends over for dinner and drinks. As the wine was drunk, the subject of beer styles came up. Specifically, how to know what you’re ordering is going to be to your liking. My fellow brewer and I agreed that the best beer labels and menus are ones that feature OG, IBU, and ABV. In listing these measurements, a label will essentially say how much malt (OG), how bitter (IBU), and how alcoholic (ABV) the beer is. Let’s expand a little on what exactly these three measurements mean to you.
Original gravity (OG) is the measurement that is used to determine how dense a beer is prior to being converted into alcohol (fermented). With the many different styles of beer, this measurement will include everything in the beer solution (wort) including ingredients like malts, oils from hops, oats, sugars, and any other adjuncts used to create the unique taste of a beer. Keep in mind that this does not necessarily factor into the color of a beer. The higher the OG, the denser the beer. So, a gravity reading of ’20′ (1.083 in home brewer terms) means a fairly dense beer, while a gravity reading of ’10′ (1.040) will mean a fairly light bodied beer.
Now that we have determined how malty (or sweet) a beer has the potential of being, let’s talk about another side of the equation; bitterness. The International Bittering Unit (IBU) is a mathematical measurement of how bitter the hops are used in a beer. This takes the alpha acidity, the quantity used, and how long the hops are boiled for and converts these numbers into a single number. A beer with a rating of 10 IBUs would have little hop character (bitterness), a beer with 40 IBUs would be considered to have an average hop character, and a beer with 70+ IBUs would be considered a very hoppy beer.
With beer, sweet and bitter are designed to compliment each other. You may have a high IBU count like 85, which may signal a bitter beer, but with an OG of 21, the sweetness would balance out the bitterness. That is, unless it’s a very alcoholic beer.
The final piece of the puzzle is alcohol, or Alcohol by volume (ABV). For the geeks out there, alcohol is the simple measurement of the difference between OG and FG (final gravity, or gravity after fermenting). The greater the difference between the OG and FG numbers the more alcohol you have in your beer. We may have established that a higher gravity beer with an OG of 20 has a lot of ‘stuff’ in it, but we haven’t said how much of that stuff can be converted into alcohol. Certain ingredients in beer simply do not convert into alcohol. These are typically called ‘unfermentable sugars’. There is a direct correlation between the sweetness you taste in a beer, and the unfermentable sugars that are left after the alcohol has taken what it needs. To use our example above, a beer with an IBU count of 85, an OG of 21, and an ABV of 9% would produce a very hoppy beer (an IPA). This is because almost all of the sweetness (sugar) from the OG was converted into alcohol. A similar beer with 85 IBUs, a 21 OG, and 5% ABV would be a much more malty beer (a brown ale). This beer could be the result of several factors. Unfermentable sugars may have primarily been used, the malt wasn’t brewed correctly, or the yeast wasn’t up to the challenge of converting all those sugars.
So where does yeast come into play? We’ll have to save that for another time. Knowing what you know now, can you determine what beer you would prefer from the menu above? I took this photo on a recent trip to Golden City Brewery in Golden, Colorado.
