Nitro Fever Hits Bottles

 Nitro beer sounds like a power adjunct borrowed from Wrestlemania or maybe even drag racing’s Nitro Funny Cars.

 When it comes to beer, the term "nitro", or N2, refers to an alternative method of making beer bubbly. Typically, brewers use carbonation, either by bottle conditioning or through a process known as force carbonation. Getting N2 into a beer is trickier than CO2, as it is about eighty times less soluble in liquid. There is no way to bottle condition a beer with nitrogen. It can't be produced naturally, and therefore must be forced into the beer. 

On draft, nitro beer is typically pumped with a 75 percent nitrogen and 25 percent carbon solution. This mixture is known colloquially as beer gas, or Guinness gas. The use of carbon mixed with nitrogen keeps the beer from going flat. Before it reaches the glass, it is shoved through a "restrictor plate", a perforated disk which agitates the nitrogen, producing the copious froth for which nitro is known.

Credit has to be given to Guinness, which singlehandedly pioneered the effort to bring nitro to fruition. The Guinness efforts began in the mid-1940's, not long after metal kegs were introduced. The company found nitrogen desirable due to its lack of odor and color. It was also quite stable, resulting in a longer lasting head. Because it is so much less soluble in water, nitrogen has more trouble dissolving through bubble walls and remains comfortably trapped within beer. The proportion of N2 in beer is also very similar to the amount in our atmosphere, making it less prone to escape. 

By 1964, Guinness had successfully produced the draft style so commonly associated with its flagship brew. But Guinness wanted to make nitro available at home and it was a bit of a headache. The researchers struggled to find a method where the drinker didn't have to actively engage the nitrogen to create a head. Their history of research and design foibles reads like a WWII spy-gadget compendium, including syringe-like devices and ultrasonic cup holders designed to initiate the nitrogenation process. 

The breakthrough came with the creation of the "widget," a small, hollow piece of plastic with a tiny hole in it. The widget is inserted into the can along with a small amount of liquid nitrogen and the can is quickly sealed. The nitrogen then vaporizes and expands, forcing a small amount of air and beer into the widget, and dissolving the rest of the nitrogen into the beer. When a can or bottle is opened, that pressure is rapidly released, along with the N2 and beer in the widget. The gas surges upward, creating the foamy head.

Other brands, notably Boddington’s Pub Ale, have also introduced a widget. The principle remains the same – a plastic, sphere-shaped container with tiny holes that allow nitrogen and beer to fill it during the canning process. The N2 rushes out through a nozzle-like opening when the can is opened, boosting the foaming action much in the same way as the perforated plate on a tap.

But what about the taste? 

Carbon reacts chemically with beer to form a slightly acidic flavor profile, accentuated by larger and more "prickly" bubbles. Nitrogen is inert, which translates to what some might consider a flatter taste profile. Hops especially are numbed without carbon's punch. On the upside, the dulling of hops allows often overpowered malts to shine, which works well with stouts and other darker selections. And then there's the mouthfeel, which is undeniably creamy and smooth, like an ice cream float in beer form. The change in flavor-focus is a polarizing subject among craft brewers and drinkers alike.

In an act of scientific martyrdom, I compared Left Hand's regular Milk Stout with its Nitro brethren. Admittedly, I was already a fan of the carbonated version, but the choice wasn't random. Aside from being one of the only beers readily available in both forms, Left Hand claims the title of being the first brewery in North America to sell a bottled nitro beer. And they do it without a widget. Exactly how is a bit of a secret. 

Poured side by side at a temperature of about 45 degrees, the first thing I notice is the head, which lingers longer (seemingly indefinitely) on the Nitro. I can hear the earnest fizz of some carbonation, but the N2 cascades in silence.  I sip the regular Milk Stout. Hops peek out briefly before disappearing in a vortex of smoky, roasty, and cereal-like malts. I take a draw of the Nitro. It's very smooth, but all the flavors so evident in the regular milk stout are muted. The hops are practically nonexistent. I continue oscillating between the two, though my mouth is confused, and I feel somewhat unsatisfied as a result.

I'm halfway through both beers and having trouble understanding the appeal of nitrogen, aside from its texture.  Unsurprisingly, I begin to relax a little. I stop trying to actively discern the difference, letting both linger longer.  In this state, the Nitro makes its move. The Nitro Milk Stout has a much better finish. Nitro exists independently of the beer itself, while carbonation is chemically linked with the beer. The regular Milk Stout ends with the familiar carbonic bite, while the Nitro finishes with malts. What many consider a Frankenstein-ish abomination could actually be allowing you to taste the flavors of your beer in a more natural state.

The N2 has no taste; it's purely for the mouthfeel. Thus, you should drink it differently than how you would drink a carbonated beer. Swishing and tonguing it aren't going to add to the flavor. Let it sit on your tongue and make its statement. Which style you choose will depend on the kind of statement you want to hear. Nitro's subtle taste character and drinkability lend it to casual sessions and refreshment, but if you're looking for unabashed statements of malts and hops, stick with carbonation. 

The use of nitrogen in beers is still in its fetal stages. It's difficult to make, especially considering a less than firm footing in the craft beer market. It is patently different from carbonated beer, and easily misunderstood. Yet it is aesthetically pleasing to the eye and mouth.  There's a lot of potential for N2 to clarify overpowering beers in terms of taste.  Think Russian imperial stouts, for example. Nowadays, you can reasonably expect to find a nitro tap at a respectable dispensary of beer. Draft nitros have gained better footing on the West Coast, but a thorough search should turn up a few in any part of the country. More breweries are coming out with canned versions as well, including the Oskar Blues and Sierra Nevada brands. Many British brewers offer the same nitro technology Guinness uses, such as Young's, Murphy's, and Old Speckled Hen. 

See for yourself which style deserves the title belt. You don't have to be macho to enjoy a nitro beer. Just sit back and let the flavor come to you.