When people talk of nitro, it’s a reference to the type of gas used in the carbonation process. “It gives complexity to beer,” says Terence Sullivan of Sierra Nevada, which released a nitrogenated stout named Knightro at their pub last year. A strong number of brewpubs throughout the country also offer nitro beers.
The number of bars adding independent (non-branded) nitro taps is growing as more establishments embrace craft beer and buck the traditions of larger breweries.Ĭraft outfits like Sierra Nevada Brewing Co., Sixpoint Brewery, Sly Fox Beer, Yards Brewing Company and more are adding nitro to their arsenals. While nitro is normally associated with a certain brewery of Irish heritage hailing from Dublin, more and more craft breweries are embracing the nitrogenated method and adding such beers to their lineups. However, the easier way to get a nitro head is just to bubble nitrogen (or even air) through a 0.5 micron carb stone after you've poured the beer.We can't send you beer, but we can send you our newsletter! Sign Up Now Whether you can do this at home depends on your access to liquid nitrogen and nano-tech.
In the canned version of Nitro Stout they use a widget similar to Guinness draftflow system. I've seen speculation that Left Hand etch the interior base of the bottle to provide nucleation sites. It's not clear whether Vault do anything to assist the formation of small bubbles other than the "vigorous pour" advice. Left Hand have been pretty quiet about how they get round this problem, but another brewer, Vault, has hinted that they inject liquid nitrogen into the bottle and then cap it quickly before it all boils off. the whole mechanism must be in a pressurised chamber. In order to counter-pressure bottle it the head pressure must be maintained while the bottle is capped i.e. As soon as the head pressure is released from the beer the nitrogen comes out of solution and is gone. The problem with bottling nitro beer is that nitrogen won't stay in a supersaturated solution in the way that CO2 does. So back to the dual problems of dissolving nitrogen and creating small bubbles. Hence it will stay as small bubbles, and a thick dense foam. Because nitrogen is much less soluble in the bubble wall it has a far lesser tendency to disproportionation. By a process known as disproportionation small bubbles get smaller and large bubbles get larger.
With CO2 the gas at pressure dissolves into the wall of the bubble, and can then effuse into an adjacent bubble. In a typical beer the pressure inside a 1 micron bubble is about 3bar. In short the difficulty in producing small bubbles is that surface tension means the gas pressure must be higher. In this paper he explains why nitrogen produces a much better head than carbon dioxide. Professor Charles Bamforth is the undisputed King of Froth. This may not sound like much but that equates to about 40ml of nitrogen in a pint, and is enough to create a 1cm head. The US version of the original Guinness draught flow patent specifies a dissolved nitrogen content of 0.015 to 0.035 vols. Nitrogen dissolved in the beer, and some means of getting the nitrogen out of the beer as small bubbles. To get a nitro head on canned or bottled beer you need two things.
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