can't get any fizz

[sam c]

did a wheat beer two weekends ago and kegged 15 litres of it last weekend. it was primed with 70 g sugar and left in the warm for 5 days. there was alot of pressure built up in the keg but no fizz in the pint so i move the keg outside into the cool but still after 3 days there is loads of presssure but still no fizz at all.

could it be that the extra space in the top of the keg is causing this? ( not sure why though) or am i just being impatient? as its a wheat beer it really needs to be well carbonated.

[sam c]

yeah it is in a plastic keg. i was thinking the same thing last night, should have bottled it.oh well i guess all i can do then is leave it as you suggest and see how fizzy it gets. i think it could do with a little time to mature any how as it tastes a little wishy washy at the moment. i think that might have something to do though with the munich yeast.

cheers

[Invalid Stout]

Bavarian wheat beer is traditionally bottled anyway, and pouring it is half the fun.

[mysterio]

I would bottle it, wheat beer can taste pretty insipid when it's flat.

[Dr. Dextrin]

If you primed with sugar you shouldn't need to wait for the CO2 to dissolve in the beer. The CO2 is being produced within the beer and will already be in solution.

Some beers just don't taste fizzy unless very well carbonated. I suspect wheat beers are like that because I can't ever remember having one that didn't come out of a bottle or a keg system that looked well-pressurised. I'd go for the bottling option. You need enough gas in there to give a good bead in the glass, so you can put a slice of lemon in and watch it bob up & down, like they do in Germany.

[Dr. Dextrin]

Why does some co2 escape when you open the bottle then ?

Because CO2 produced in the beer gradually comes out of solution and builds up pressure in the space above the beer. That bit escapes when you pop the cap.

The point is, if you prime with sugar, the CO2 is moving from the beer into the head space. Whereas if you apply top pressure, it has to move the other way. Moving in and out of solution takes a little while, so if you prime you initially get fizz and little pressure, but if you apply top pressure, you initially get pressure and little fizz.

[sam c]

cheers chaps.

i like the idea of bottling but am far too hung over today so it wouldn't get done till next weekend. i dont have any more munich yeast to add at bottling and it was in the fermenter for 2 weeks and now in the keg for 1 week and in the cold outside for 3 days. do you think the yeast will still be able to eat up more sugars? i do have some s-05 but dont want to loose any flavours from the munich yeast( what little flavour there seems to be.)

i take it i would need to re-prime when bottling as the previous sugars have probably all been used.if so should i prime with the usual amount?

i also took 10 litres of this brew and racked it ontop of 550ml of watermelon juice so it could bottle it all up at the same time.

[sam c]

cheers chris.

as i cant really do anything untill next weekend any way what i will do is wait and see if it gets any fizz and if im happy then i shall leave it.

if not i will re-prime with S-05 as suggested.

one more question for you if you dont mind. in the keg there is about 15 litres and i also have another 10 litres of the watermelon wheat in secondary. would it be possible for me to re-hydrate the S-05 and split it to use in each brew? i am a little worried that the munich yeast in the watermelon wheat is not gonna be any good. just a hunch.

[Dr. Dextrin]

It depends on the temperature of the beer. Warmer beer, eg beer at room temperature or the temperature at which beers are normally kept at for the first week becomes saturated with co2 much sooner than cold beer so after the saturation point is reached, the co2 is given off as soon as it is produced.

Chilling the beer and storing it for a week or two allows the co2 that has been produced, which is under pressure at this point to become absorbed into the beer.

Sorry, perhaps I misunderstood . Yes, of course, if you lower the temperature then it will take a while for equilibrium to be re-established and to some extent that will involve CO2 dissolving into the beer. If you apply top pressure via a regulator (that is, at constant pressure) then what you describe sounds about right to me.

However, I'm not altogether convinced that the same thing can happen at constant volume (like in a sealed bottle or keg). As far as I can see, in that case there isn't very much scope for gas to move between the beer and the space above, at least not if the vessel is nearly full - as it usually is.

<technical warning="Those of a nervous disposition, look away now">

Sorry to launch into a technical discussion, but hopefully the OP's question has been answered above and I think it's vitally important to understand the fundamental things in life, like how to put fizz into beer , so here's how I see it...

If the beer gets saturated with CO2 as you describe, it will start to move out of solution into the head space. But that will rapidly increase the pressure, particularly if there isn't much space for it to move into. Increasing the pressure increases the solubility of CO2 in beer (it's pretty much proportional to the pressure), so the beer will no longer be saturated and the gas will tend to remain in solution to a much greater extent than if the pressure was constant.

If you then cool the beer, the pressure will drop. Partly this is because CO2 starts to move out of the head space and into the beer (the reverse of the process above), but also because the gas exerts less pressure at a lower temperature. This reduced pressure reduces the solubility of CO2 in the beer, so the process is again self-limiting.

To illustrate, consider a bottle with the head space occupying (say) 1/20 of the total volume and suppose the internal pressure is zero (i.e. atmospheric) and there is 1 volume of CO2 dissolved in each volume of beer. This means that 1/20 of the CO2 will be in the head space. Now suppose the priming sugar generates another 1 volume of CO2. Where does it go? If it all goes into the head space, the internal pressure would have to rise to somewhere around 20 atmospheres. That's probably way beyond what any bottle will stand. Instead, the internal pressure will probably go up to around 1 atmosphere (consulting a carbonation table). At that pressure, about 1/20 of the CO2 would reside in the head space - that's pretty much the same fraction as when we started.

</technical>

So as far as I can see, no matter how much you cool the bottle, you can only increase the amount of CO2 dissolved in the beer by at most 5% because that's all there is left that isn't already dissolved. In practice, only a small part of that will actually dissolve, so if you increased the fizz by 1% you'd be doing well. A sealed keg might have a bit more head space, but you'd still be struggling to see much effect from cooling it.

I must say I've never thought about this in that much detail before, so is there a flaw in my argument? It seems to imply that whatever benefit comes from cooling your bottles after conditioning, it isn't due to the CO2 dissolving into the beer. With a Cornie connected to a regulator, it would be different, of course.

[sam c]

great idea for the priming chris. will be doing that at the weekend then. cheers

dr dextrin, thanks for the info. might have to read it again to get it all in my head

[dave-o]

Nothing useful to add, but i wanted to suggest that you change the title to "I can't get no.....carbonation".

I'll get my coat.

[Dr. Dextrin]

In the case of priming beerthe amount of co2 produced will in most if not all cases more than the beer can absorb during its warm conditioning phase, regardless pressure and the result is a lot of co2 under pressure in the head space of the cask or bottle. Particularly bottles as the volume is fixed and they tend to seal better than plastic pressure barrels, plastic pressure barrels tend to expand (and leak).

The only way to get the desired level of carbonation is to move the vessel into a cool place at the temperature used to calculate the amount of priming sugar required, after the priming sugars have fermented out. This temperature is usually cooler than the temperature at which yeast is active and is why you have the warm conditioning phase (fermentation temperature) and the cold conditioning phase (cellar temperature)

That may be conventional wisdom but I can't see how it can be correct. The reason, basically, is that it isn't possible to store enough CO2 in the gap at the top of a bottle to have much impact on the carbonation of the beer.

I've just measured the head space in one of my pint bottles and it's only 1.8% of the total volume of the bottle. Even if the bottle could withstand 10 atmospheres of pressure without exploding (extremely unlikely), I'd still only be able to get enough CO2 into that space to provide a carbonation level of 0.18 volumes of CO2 per volume of beer. That's an insignificant amount given that most bottled beers are carbonated at well over 2 volumes.

[sam c]

hi,

still haven't got around to doing this yet but im thinking that i will do it tonight. do you think it is still ok even after this long in the keg? i think it's been in there almost three weeks now.

thanks

[Mountain]

Was 70grams enough for 15L of a wheatbeer?
Wheatbeers tend to be highly carbonated.
Off the top of my head, last time I did 19L of Wheatbeer in a corny I added around 300g of priming sugar.

[sam c]

no i meant bottling it from the keg, but having had second thoughts i really cant be bothered. it has loads of pressure in the keg and has been outside in the cold for i think 2 weeks now and is very slightly fizzy. i have decided in the last ten mins that will have to do. it does taste quite good now just lacking the fizz.

as far as 70g priming sugar for 15 litres i dont really know. i think if it was in bottles it would have been ok but it just hasn't carbonated but like i said there is loads of pressure.

thanks again, time to get drinking