One for the geeks

Ok, so here is a question that is more about understanding yeast than really changing my process on a regular basis, as I don’t believe this should happen too often. I have been searching for an answer to this question and found nothing useful. First I have to say: I have started conditioning in kegs (adding sugar to kegs in order to gas). I know it is a bit silly and no one seems to be doing this, but I kind of like the idea of not using a ressource (gas, which like so many other ressources has been in shorter supply these months) and letting yeast do the work, which it does so well anyway and for cheaper. The question I have is this: if I plan to be away on vacation for a couple of weeks after kegging, say if I leave about 5-6 days after kegging (and adding the sugar to the keg), do you think it would be better to let the beer condition in the keg a little too long (for example over 3-4 weeks) or too little, that is put it in the kegerator after only 5-6 days? I am a bit scared that the sugar I will add when kegging won’t have been eaten up by then and the yeast won’t be able to finish the job in the kegerator, but at the same time if most of the sugar is eaten anyway, I would much rather put the keg in the kegerator, letting the yeast putter away slowly and maybe finishing the job slowly, rather than leaving the keg in the warmth for too long because of the risk for oxydation (especially if it is a pretty hoppy beer) and because it will affect how long the beer keeps (again, I am not talking about barley wine here, but rather something “light” and hoppy, like an IPA). I know it is not something that should happen often, and I know that most of you will just say: try both and see what happens, but if someone already has some insights about this, I would rather have your advice than find out by making a whole keg “go meh”. Actually, maybe no one has tried this with a keg, but I would be surprised if no one has tried to put bottles in the cold on the early side of conditioning and what kind of result that produced. Thanks a lot for any insight and cheers!

You shouldn’t worry about oxydation since the yeast will consume to oxygen to help it make CO2.

Temperature will be dependant entirely on the health and type of yeast you are using. If it’s able to work well at kegerator temps, then no problem. Although it will be a much slower process than otherwise. Hope this helps…

Thanks for your thoughts. I guess it would be safer to just leave the keg out of the kegerator then, if I understand you right, since you don’t seem to think there is any potential downside. But how can you tell if a yeast strain can “work well” at kegerator temps? The one I was planning to use for that beer is US-05 (Saf-Ale). Obviously, the kegerator temp is going to be much lower than the range given by Fermentis, but the yeast still putters away a bit, as you can tell by the evolution of the taste as a beer ages in a cold keg (beyond the clearing). From experience, I am pretty convinced that Ales benefit from aging, not just lagers, so I usually leave them in the kegerator for at least 10 days, and then I start tasting them and I can still see an evolution continuing over the next weeks. So even ale yeast seems to be “doing something” at cold temps, I just wonder if the yeast can actually eat up sugar at that temperature. And if it does, I kind of like the idea of letting the yeast finish up eating the sugar really slowly over a few weeks. But if it doesn’t, the thought of having some sugar left in the beer is not very pleasant. First world problem, I know, but still.

I think the evolution you’re seeing is not so much the yeast “working” the beer as it is proteins and break falling out of suspension.

I use the CBDS on almost all my kegs, so I’m drawing from the top of the keg as opposed to the bottom. I also force-carbonate at serving temps (5-6C) and pressure (9-11psi) after an initial blast at approx 30psi to seal the lids when I keg. I usually don’t pour from a keg until 7-10 of being hooked up and I don’t see much evolution after the first pours.



Very interesting. You might be right. I can’t really tell what the cause of the change is of course, and it is fairly minor, so it definitely could be as you say more a matter of “physical” change rather than yeast-induced one, but I really think that there is a change, at least with some beers. I guess it could also be sometimes a simple mellowing of the hops, as most of my beers are IPAs or at least hoppier German-style ones. I guess you don’t need to understand it to enjoy it, but it is still nicer to “savor with knowledge”. Anyway, thanks for your thoughts and cheers.

I used to carbonate with sugar in my kegs, never had a problem. I used less sugar per litre than for bottling. I would leave the keg at room temperature for a couple of weeks, then put it in the fridge.

Ok, thanks. Have you ever tried putting the keg in the fridge only 5 days after kegging (and adding sugar) or have you tried leaving it at room temperature for a month?

I only bottle condition my beer and if I needed to choose I would go with 3-4 weeks at room temp vs chilling after 5-6 days. It would be interesting to compare them - maybe you could bottle a few and throw those in the fridge and leave the rest in the keg at room temp.

Thanks for the input. I think you are right: more chance of problems with chilling too early than the opposite. Cheers.

Absolutely. Better leave the keg to referment for longer than for not enough time. I’d say 2 weeks minimum at room temperature.

If you can, you could install a pressure gauge on the keg (like with a spunding valve) and wait for the pressure to stabilize for a few days. Based on the typical pressure-temperature and CO2 volume chart, you can expect a little over 32 psi at room temperature for 2.5 volumes of CO2.

Thanks. I will try that.