What is it about guinness.....

Does anyone know what it is about Murphy's and Guinness that allows nitrogen dispensing to create that waterfall effect? I have tried with other stouts and it seems like it just doesn't work as well.

Anyone have a semi-scientific explanation for what Irish Stout recipes have over other stouts when it comes to nitrogen dispensing? I have found other ales/stouts can become foamy without settling, even after experimenting with various pressures - none really do it sometimes. Has anyone else run into this?

Thanks!

IMHO, Boddington's has the prettiest of the waterfall effect

Beer Gas (75% Nitrogen and 25% CO2) dispenses through a Stout Faucet that has a restricter plate in the nozzle that creates the cascading bubbles and smooth creamy head. It requires a higher pressure to push through the restricter plate, and if you did that with CO2 it would overcarbonate the beer, thus 3/4 Nitrogen is used as it does not dissolve in the beer like CO2. I don't think the recipes make too much of a difference. You can do it with other styles too.

This is a Stout Faucet



I may have misunderstood your post.

True. Belhaven's too. My question is really posed to get to the root of the phenomenon in order to replicate it, not necessarily seperate stouts from the rest. Perhaps, though, by examining the beers that can waterfall we can figure out why they do it?

My guess is that the nitrogen is trying to escape upwards while the heavier carbon dioxide "waterfalls" downwards until all the nitrogen is gone, by which time most of the head has settled...

ODaniel - my question should have been framed by saying that a beer gas setup used for different styles seems to yield very different results. I have found that by using the setup you describe, I may end up having one batch end up perfectly waterfalling, while another fills the glass with foam and waterfalls very slowly and lacks the creamy fine bubble mouth feel.

Maybe variations in carbonation have a contributing role? Maybe FG? Maybe operator error?

It might have to do with carbonation volume and dispensing pressure. Are you talking commercially or homebrew or both? I've had some English something yellow beer through a Stout faucet and it cascaded/waterfalled just like Guinness. This was at a bar. I have 2 Guinness faucets, but need beer gas. Took the restricter plate out for now.

maybe it does have to do with volumes of carbonation. I am dealing with homebrew (not commercial kegs) so there is always a chance for variation in carb levels. I tried to eliminate that as the culprit by letting it rest at 5 psi for a week or more, but still had generally unfavorable results. Maybe 5 psi isn't low enough to naturally lower carbonation?

I'll have to try with my next pale ale batch and keep the carb volumes low as an experiment.

How are you carbing it? The carbonation volume is determined by a certain PSI at a certain temp. There are charts all over the internet. Simply lowering the PSI won't lower the carbonation (after it's already carbed) - to do that you'll have to shake the keg and bleed the pressure, maybe a few times. Are you force carbing it with a CO2 tank and then hooking up your beer gas tank? What pressure are you dispensing? With beer gas through a stout faucet, it's recommended 38psi and for a Stout 42 degrees F.

Dispensing Stout Beer: Guinness, Murphy's

Beer doesn't absorb Nitrogen?

I think you mean it doesn't absorb N2 as quickly...but Scuba divers would sure like it if liquids didn't absorb N2...there wouldn't be Nitrogen Narcosis...and Nitrogen saturation wouldn't be the problem that it is in real life.

It's in there...it just takes a lot more effort to get it disolved into solution.

I have no scientific basis...but I think the guinness separating on top in a black and tan is a result of the Nitrogen in solution having a lower molecular weight than CO2 in solution. If you take a stout that isn't "nitrogenated"...I think you'll find it particuarly difficult to layer them in a glass. But I'd have to differ to Bill Nye the Science guy on that one...

Yea I just mean it doesn't dissolve into the beer like CO2 so it won't overcarbonate and will be smooth.

I have been force carbonating at 15 psi and about 40dF for a couple of weeks and then switching to the beer gas at 25 psi to dispense. The carbonation has been good for other brews (and for this beer after switching to a regular tap), so I haven't been convinced that was the only problem. I'll try dispensing at 35 psi next time and see how that works. Last time I actually kept reducing the pressure to lower the foam, but maybe that was wrong thinking?

AN_TKE said:

that waterfall effect?

Click to expand...

I found out what you were describing in this video.

Looks pretty cool:

[ame=http://www.youtube.com/watch?v=1DAIK2I8y8Q]YouTube - Guinness: How to pour and enjoy the perfect pint[/ame]

A combination of low carbonation and high serving pressure through a diffuser plate produces the effect. Nitrogen is used to achieve the high serving pressure because it's approximately 100 times less water soluble than carbon dioxide. At serving pressures, nitrogen alone will never produce an effervescent effect in water (or water based) liquids.

So, here's how it goes:
The beer is carbonated with carbon dioxide to a low level (around 1.0 volume). Then it's served with nitrogen achieve a high pressure (30-40 psi) pour without the risk of overcarbonation.

If you keep googling on the subject...you'll find...

Most people recommend that you use a Stainless Steel Sintered Stone...to mist the N2 blend into solution. It's best done with a modified lid...that has an additional gas connector...tubing to the bottom of the keg...connected to the sintered stone. Get the keg really cold. Apply N2 blend to this stone, gradually increasing the pressure to 35 psi...let sit for an hour. Disconnect...bleed off the head pressure thru the regular gas connector...and repeat the process. If you do this 3-6 times...you'll get some Nitrogen into solution along with your CO2. The only way to tell when you're there is to do a pour test...to see if it's giving you the desired cascading effect...as the head is forming. And a creamy head about 1/2" thick when all settled out.

Alternatively...I've heard some people attach the sintered stone to the little gas down tube. They invert the keg for Nitrogenating. Then bleed the head pressure off from the liquid connector while the keg is inverted (look out for a bit of liquid to come out). This cuts down on the expense of having to modify the keg with an additional gas connector.

I think you'll find the head will be creamier if you take the time to actually disolve some nitrogen into the beer. You may be happy just to serve a low carbonated beer thru a diffuser (stout) faucet... It's up to you to see if the difference is worth the effort. I'm hooked to the Guinness effect...and just have to have it.

Just my .02 worth on the subject...

I haven't had my BEER MIX tank that long...so I'm still getting it sorted out myself.

Once again, it's not about getting nitrogen into the beer. By using beer gas and a carbonation stone, you're force carbonating the beer (putting CO2 into solution - beer gas is a mix of CO2 and N2). When the pour looks correct, you've achieved the proper level of carbonation, NOT nitrogenation. See my post above.

maybe i simply had just to much dissolved CO2. I'll try to hit the 1 volume next time and see how it works. Since I have been able to get the cascade on some batches and i never used a carbonation stone, I am more inclined to believe that the nitro is to perform as described by Yuri.

thanks.

To reiterate Yuri's point, the nitrogen is not going into the beer in any useful quantity. It's simply there to increase the head pressure in the keg. The solubility of CO2 in the beer is dependent on the PARTIAL PRESSURE of CO2 in the gas space. Normally the headspace is 100% CO2 (so the partial pressure is the same as the total pressure), but if you're using beer gas it's only 1/4 of the total pressure. So, carbonating a beer with pure CO2 at 5 psig will give you the same results as carbonating with beer gas at 20psig.

You'd probably achieve identical results from a stout faucet by carbonating with pure CO2, then switching to beer gas when you get the carbonation you want.

I keep my Stout Regulator set at 30 psi...and I've got a 25/75 blend...so 1/4 of the partial pressure is CO2. So cask condition your stout at 1/4 of 30 psi...say around 7.5 psi. Then just bump up the CO2 pressure momentarily to serving pressure of 30 psi to pour a pint...then bleed off the extra pressure in the keg when you're done so you don't overcarbonate.

Now pour a black and tan like that. If it stays in perfect layers...then I'm satisfied that N2 has nothing to do with Guinness' creaminess...other than forcing it through the restrictor plate

I'd try it...but I don't have any Stout in the fermenter right now. And only a couple of pints left of Guinness (if I'm lucky )

I have poured carbonated homebrew stout through my stout faucet before...with no nitrogen...and I was NEVER able to get the black and tan layers. The two beers just blended together... very frustrating.

My very first pour with kegged Guinness...perfect layers. Layers that linger the entire time you're drinking the pint.

I came accost this thread as I just bought a stout faucet that I plan to use mostly as a co2 faucet without the restrictor.

The reason Guinness floats on top has really nothing to do with the gas but with the final gravity. Guinness is a fairly low gravity beer the darkness is because of the specialty malt used not intensity. If you pour a lower FG beer on top of a heavier FG beer they will stay separated.