What are nitrogenated beers? You have probably seen them at an Irish pub, with the funny handle and the longer spigot on the tap. The beer might involve a multiple step pouring process and a mesmerizing “reverse cascading” effect down the glass, but how does it work and why would you shouldn’t order it.
Back in the day when beers were served on casks that were made from wood, it was relatively uncarbonated by today’s standards because the vessels just could not hold the pressure. You might have experienced or heard of the stories about warm and flat beer in England they call “real ale”, but it is not flat or warm. Real ale is drawn through a hand pump and served off cask at cellar temperatures, around 55F. Historically, just plain air was in contact with beer, so about 80% nitrogen and 20% oxygen. The resulting beer is rich and creamy with a head that seems to last all day.
One of the greatest enemies to beer is oxygen, which is a big problem if a cask is not emptied over the course of a few several days. Beers served on “nitro” are dispensed using a mixture of about 70% nitrogen and 30% carbon dioxide, colloquially called “beer gas”. When you order nitro beers on draft, it is forced through a fine screen while the beer gas mixture is forced into the beer. The nitrogen knocks out the CO2 out of solution that is normally present in the beer and creating a very lightly carbonated beer with a very thick, dense and fine head of foam. The dispensing is a mechanical function, so if you have ever torn open a can or looked at a bottle of Guinness, there is a plastic widget in there that nitrogenates the beer as soon as you crack it open.
Nitrogen, however, does not stay in solution as well as CO2. A nitro beer should be drunk quickly because the nitrogen comes out of solution so rapidly that the beer will be flat less than 30 minutes. Have ever tried to get a growler full of nitro beer? It would be just plain flat by the time you even get it home. Most breweries will not put nitrogenated beer in a growler anyways.
What beers are conducive to being served “on nitro”. The answer, in my opinion, is none. Nitro beers are solving a problem that has already been fixed. The problem of having a vessel that can’t hold enough pressure for the beer to dispense itself and stay carbonated, has already been fixed with modern packaging technology. There are breweries and bars that are now throwing nearly any beer on nitro, perhaps for novelty sake. Nitrogen has this magical ability to absolutely destroy hop aroma, so putting a hoppy beer such as an IPA on nitro is just undoing all the work the brewer did by adding in all those hops. If a nitrogenated beer needs to be drunk quickly before it goes flat, then why would someone put an 11% Russian imperial stout with coffee and cocoa and aged in bourbon barrels in nitro, unless they desire an irresponsible rate of consumption?
Next time you stop at your favorite drinking establishment and see they have a nitro beer, ask yourself, is it low alcohol, light in body and needs that crutch called nitrogen to make that beer drinkable? Just say no.
November 7, 2013