Sugar in keg

[kieran o connor]

Just wondering if anyone has ever tried adding sugar to a keg (instead of gassing with CO2), left it for a few weeks to generate CO2, then hooked it up to the gas to serve.

I always save a couple of bottles when kegging, spoonful of brown sugar and stow them away in a cupboard for for a month or so then crack them after the keg has finished. They always taste different to the keg pour, more mellow somehow like they've been appropriately 'aged'.

It occurred to me the back of the cupboard approach could also be taken in a keg without all the hassle of bottle washing etc. Interested if anyone has tried it and what were the results?

 

[Half-baked]

Hey Kieran, yep that’s a thing.

A lot of the brewing software (eg Brewfather) will have priming calculators for kegs, it works out needing a fair bit less sugar (half the grams/litre) than for bottles

 

[kieran o connor]

Ah interesting, thanks.

We actually had a shortage of CO2 here in NZ a little while back. Good to know there's an alternative option. Could then just use a regular compressed air cylinder for pouring

 

[MHB]

Only if you want Oxidised beer.
Mark

 

[kieran o connor]

Ah good point. Nitrogen would be a better option. Or nitrous oxide even. Laughing gas beer

 

[Hangover68]

I always do it and never had oxidized beer, i do gas it and purge the air though.

 

[An Ankoù]

Ah interesting, thanks.

We actually had a shortage of CO2 here in NZ a little while back. Good to know there's an alternative option. Could then just use a regular compressed air cylinder for pouring

You could do that, but you'd need to finish the keg at a sitting.
UK-style casks are not pressurised and they draw in air from the immediate surroundings. A cask us good for about 3 days after it has been broached, then it starts to go off very quickly. I imagine something similar would be true if you used compressed air to dispense your beer.
It would probably only be good for trad milds, bitters, porters. If you did it with lagers and hoppy IPAs you really would need to empty the keg very quickly. On the other hand, if you've primed it with sugar and already drunk half of it, the rest shouldn't be a problem with the help of a couple of mates.

 

[kieran o connor]

You could do that, but you'd need to finish the keg at a sitting.
UK-style casks are not pressurised and they draw in air from the immediate surroundings. A cask us good for about 3 days after it has been broached, then it starts to go off very quickly. I imagine something similar would be true if you used compressed air to dispense your beer.

Just teasing this out some more...
In a sealed keg that's been pressurised using sugar, there will be a layer of CO2 above the surface of the beer. If it was hooked up to compressed air to pour, after each injection of air it would mix with the CO2 then once the turbulence had subsided, the CO2 would drift down as it's heavier than air and settle in a layer above the surface of the beer, acting as an insulation blanket and reducing the opportunity for oxidation.
Plausible?

 

[MHB]

Not how it works; you need to go and read up on some of the basic Laws of gas behaviour.
Gas Laws
Mark

 

[Dave70]

Just wondering if anyone has ever tried adding sugar to a keg (instead of gassing with CO2), left it for a few weeks to generate CO2, then hooked it up to the gas to serve.

I always save a couple of bottles when kegging, spoonful of brown sugar and stow them away in a cupboard for for a month or so then crack them after the keg has finished. They always taste different to the keg pour, more mellow somehow like they've been appropriately 'aged'.

It occurred to me the back of the cupboard approach could also be taken in a keg without all the hassle of bottle washing etc. Interested if anyone has tried it and what were the results?

Use to do this when brewing 25L at a time and had a similar experience. Now I've cut back to keg sized 18L batches.

As for priming the keg, you really need to ensure you have perfect sealing. With no internal pressure (initially), you're relying on the seals on the poppet valves and lid alone to do their job 100%. Even giving it a blast of co2 to 'seat' everything wont help and it to will escape given the time it takes for the yeast to get the job done.

Nothing will make you sulk all afternoon more than tapping that eagerly anticipated keg you assumed was chugging away merrily for the last fortnight only to pull a glass of something with the effervescences of pond water.

Anyhow, this is what I did. After pulling a glass of something with the effervescences of pond water.

Choose your keg, charge it to about 35kpa (5 psi) and leave it for a few days. If you have some way to monitor this - a Blowtie spunding valve is ideal - all the better. If she holds, you're good to go. This was more or less the method we used when testing gas plumbing installations. Never asphyxiated anybody or exploded their houses due to gas leaks. A spray bottle with soapy water is also a must.

I'd recommend at least a freshen up with silicone seal kit if your kegs have got some miles on the clock.

 

[kieran o connor]

Yes, that's certainly another consideration. A pond water outcome would be more than disappointing.
Good tip!

 

[kieran o connor]

Not how it works; you need to go and read up on some of the basic Laws of gas behaviour.
Gas Laws
Mark

Thanks for the link.