It seems that nitro is everywhere. Breweries are offering old favorites in nitro packaging, and beer bars are experimenting by throwing nitro taps on well-known beers. But nitro is much more than a marketing gimmick and a pretty (make that very pretty) pour.
Let’s look a little closer at what nitro and carbon dioxide do, and how they affect the beers you drink.
Carbon dioxide, or CO2, is the most commonly used carbonation method for beer. Brewers add priming sugar to the wort when they bottle, which produces the CO2 in the bottle. The other way to get carbonation is to keg the beer and attach a CO2 tank to force carbonate the beer. The advantage to kegging is being able to control the amount of carbonation and the ability to adjust it as needed, making it just right for the beer being served.
Now we get to the taste aspect of CO2. CO2 is an acid, which adds a bit of bite to the beer. Not only does it give the beer’s flavor a nice dash of tartness, it provides a lighter texture than a flat liquid—even dryness—depending on the amount. When the bubbles hit your tongue, the release of the acid interacts with the pain receptors in your mouth. Surprisingly, the pain receptors cause a pleasurable sensation that reacts with the beer’s flavors because it makes your taste neurons fire. You’ll notice that when you drink a flat beer or soda, a lot more of the malt and sweetness comes through but sometimes to the point of making it undrinkable. Add carbonation and it’s awesome in a can.
Now that you have a bit of an understanding of what CO2 does, let’s look at nitro. Nitro systems are actually a mixture of 70 percent nitro and 30 percent CO2, and not just straight nitro. When you pour a nitro beer, you’ll notice that instead of the beer foaming over with big effervescent bubbles, it produces a lovely cascade effect inside the glass. The bubbles are much finer and more abundant than CO2 bubbles, and the head is thicker and foamier. Some breweries have incorporated nitro in their bottles and cans, while others opt for the beer to be kegged and tapped with nitro after they’re shipped to taprooms.
You’re probably wondering what the big difference is between nitro and CO2, and why go to all the trouble to get nitro when CO2 is easier to work with and less expensive. Nitro produces a creamier mouthfeel and brings out the sweeter qualities of the beer. It’s recommended more for sweeter beers (for example, most porters and stouts), but I’ve seen it used for wheats and IPAs, too. Those who like the high IBUs of an IPA will be in for some disappointment, however—the nitro suppresses much of the hops bitterness. That said, if drinking an IPA on nitro floats your boat, I’m not going to tell you not to swim out to sea!
Now comes the fun part: comparing the two methods. Several breweries have produced beers that come in CO2 and nitro versions, which gives you the chance to try the same brew served two ways. Pour yourself a glass of each, and do a comparison. What do you notice more about the nitro vs. the CO2? Is the roastiness of a porter coming out much more in the CO2 version, but the lactose showing through much more in the nitro version? Do you prefer one over the other? What else do you notice?
Here are some beers that have both a nitro and CO2 version to try this weekend:
Oskar Blues Old Chub (Lyons, Colorado)
Left Hand Milk Stout (Longmont, Colorado)
Breckenridge Brewery Vanilla Porter (Breckenridge, Colorado)
Founders Pale Ale (Grand Rapids, Michigan)
Sam Adams Nitro Coffee Stout (Boston, Massachusetts)
Tell us your favorite nitro vs. CO2 comparisons!