I have a corny keg system and am considering making an Irish Stout similar to Murphy's Irish Stout. Guiness and Murphy's have gas widgets in the cans that I believe dispense with nitrogen instead of co2 and I believe Most draught stouts also dispense with nitrogen or at least a mixture of nitrogen and co2. Am I correct? Is nitrogen necessary? Why? Is it for the head? What would happen or not haappen if I dispensed it with just co2? Any help answering these questions would be appreciated.
The dense, creamy head that you get on a pint of draught Guinness is indeed a result of the dispensing gas being a 60/40 N2/CO2 mix. A special nozzle is also used on the dispenser.
The idea is that almost all of the nitrogen comes out of solution quickly as very small bubbles. The CO2 is retained in the beer as usual, providing sparkle and flavour.
The balance of protein and carb content in a properly brewed stout also help with the formation of a dense, long- lasting head.
If you're seriously wanting to reproduce this at home, then 60/40 gas mix is available from some good equipment suppliers (or closer to home if you make friends with your local pub manager...)
I have had pretty good results though just using plain CO2 gas with a sparkler tap (the type with many tiny pinholes in the nozzle).
It should be noted that dispensing stout this way is a fairly recent thing. Traditionally, stout has been served pretty much like any other typed of beer (maybe with a little lower gas pressure). Stout poured from bottles and non-widget cans also has a more usual type of head.
Well I may have learned something new. While I have drank a many of stout I have noticed that Guiness and Murphy's has a sort of flat feel to it even with that nice white head on a very dark stout. Nitrogen??? Never thought of that one and this could explain the white head rather than the tan one and that almost flat feel to the tongue.
I know that is not much help in answering you questions but I think you are on the right track with using nitrogen. Now as for CO2/Nitrogen mix... Got me on that one too?
Something else to think about, I have seen special faucets for Irish Stouts. This could be required to get that Guiness effect too. They are a bit more expensive than getting a good stainless faucet so that in my book is something worth considering.
Yes, the mixed N2/CO2 system results in a lower level of carbonation in the drink, which has all sorts of effects on the taste and mouth-feel.
CO2 adds acidity, aroma, stimulation of the mouth by the bubbling action, and stimulation of the stomach after swallowing. The release of gas at the surface of the drink also helps to carry the aroma of the hops to the nose. Gas has a larger effect on the tasting experience than you'd at first think (after all, who enjoys a flat beer?)
Incidentally, nitrogen is generally classified as having no perceptible odour or taste.
Stouts are my particular brewing interest, and for the record I tend to prefer the traditionally bottled or kegged brew over the modern 'shaving foam' headed pint. The rich flavours and aromas just seem to come over more strongly and cleanly in the old-fashioned way of serving.
It is available commercially from quite a few brew kit suppliers. Look for 'Guinness Gas' or 'Guinness Mix'.
That is usually a variation on what is known as a 'sparkler tap'. the beer is forced through a disk with many extremely tiny holes in it. This type of tap is also commonly used to dispense what we call 'Yorkshire Bitter' (a type of traditional British bitter ale, but with lower carbonation and a fine, tight head reminiscent of draught Guinness.)
You will DEFINITELY need both the gas mix (Nitro/CO2) and the special faucet. Try going to one of your busiest pubs and ask if they have any old spare faucets that you can have/buy/trade. It is essential as well as the gas mix which you can get from a welding shop. If the shop doesn't have any nitro/CO2 you can also use "Gold Gas" which is Argon/CO2. It works just as well. Condition your stout with less than average carbonation and dispense at about 30psi through the Guinness type faucet. It's perfect!!!
The welding gas you mention would be StarGold gas.
There are several different formulations, and not all of them are suitable for dispensing stout. The best match to 'Guinness Gas' would seem to be StarGold C-25, which is 25% CO2
I haven't ever used it, but as argon and nitrogen are both flavourless and inert gases, it should work pretty much the same.
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