Does anybody know how to bottle from nitro?
I have a nitro beer that I enjoy from my kegerator on a 75:25 N:CO2 gas blend. So far all attempts to bottle this beer on the nitro mix has failed (using Blichmann's Beer Gun). It just pours flat and receives negative feedback.
Left Hand Brewing have figured this out. They're keeping it a secret as far as I can tell but I'm just hoping there's somebody out there who has also figured it out? If so, please share!
It's carbonated using normal CO2. Nitrogen isn't absorbed into beer. Its just a gas to maintain high pressures without over carbonating.
It's bottled using a counter pressure bottler with nitro. The trick to the head is the 180° angle pour.
Because canning with counter pressure is more complex Guinness uses their "widget" which is filled with nitro and releases slowly after the can is sealed. It also functions like a mentos in coke.
Edit: More about the pour. I believe this is canned in a normal way without counter pressure or widget. https://www.firestonebeer.com/beers/nitro-merlin-milk-stout.php
Pour Technique
I had a chance to experiment on a Nut Brown that I bottled last November on Nitro. It was kegged at 40psi for 3 weeks, then dropped to 3-4psi to be bottled through a standard Blichmann's beer gun and immediately capped. I opened it last night and poured according to the hard pour technique that Left Hand Brewing advise you to use with their beer (20 seconds into this clip).
The result was that the Nut Brown had the cascading bubble formation as expected from a nitro beer and developed a nice think head. The nitro bubbles were not quite as vigorous as when being poured through a tap with a creamer in it, but still took around 15-20 seconds for the cascading bubbles to stop and the head to remain steady.
Given how similar the result was I'm pretty sure that the pour technique is the "secret" about the LHB Nitro bottled range.
It is not feasible to "bottle with nitro" - meaning to eventually pour from a bottle and get the creamy nitrogen feel to the beer from a home system.
This is because the nitrogen gas does not easily dissolve into the beer under normal bottling pressures. "Beer gas" is typically a 70/30 (25/75, 50/50, etc.) mix of nitrogen and carbon dioxide. The carbon dioxide component of the mix does dissolve into the beer, so there is some remaining carbonation after the head settles.
Nitrogen "stout" taps have a slotted or holed plate across the flow of the beer. This is called a "restrictor plate". The relatively large pressure of the nitrogen causes the tiny tiny foam bubbles by forcing the beverage through this plate.
In cans and bottles an automatic "widget" activates on opening, foaming the beer with some stored nitrogen. Some breweries have special extra-pressure tanks that can hold dissolved nitrogen.
First a bit of backgound ...
To get a nitro head on canned or bottled beer you need two things. Nitrogen dissolved in the beer, and some means of getting the nitrogen out of the beer as small bubbles.
The US version of the original Guinness draught flow patent specifies a dissolved nitrogen content of 0.015 to 0.035 vols. 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. Professor Charles Bamforth is the undisputed King of Froth. In this paper he explains why nitrogen produces a much better head than carbon dioxide. In short the difficulty in producing small bubbles is that surface tension means the gas pressure must be higher. In a typical beer the pressure inside a 1 micron bubble is about 3bar. With CO2 the gas at pressure dissolves into the wall of the bubble, and can then effuse into an adjacent bubble. By a process known as disproportionation small bubbles get smaller and large bubbles get larger. Because nitrogen is much less soluble in the bubble wall it has a far lesser tendency to disproportionation. Hence it will stay as small bubbles, and a thick dense foam.
So back to the dual problems of dissolving nitrogen and creating small bubbles. The problem with bottling nitro beer is that nitrogen won't stay in a supersaturated solution in the way that CO2 does. As soon as the head pressure is released from the beer the nitrogen comes out of solution and is gone. In order to counter-pressure bottle it the head pressure must be maintained while the bottle is capped i.e. the whole mechanism must be in a pressurised chamber. 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.
It's not clear whether Vault do anything to assist the formation of small bubbles other than the "vigorous pour" advice. I've seen speculation that Left Hand etch the interior base of the bottle to provide nucleation sites. In the canned version of Nitro Stout they use a widget similar to Guinness draftflow system.
Whether you can do this at home depends on your access to liquid nitrogen and nano-tech. 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.
Bottle using CO2 only. The nitro is already in the beer.
