Warm stage for yeast to mop up stuff

[Kev888]

Question updated to ask what I actually meant to - see below!

Cheers
kev

[Kev888]

I believe that storing kegged beer too warm will shorten its life, and freezing may harm the cornie, so Ideally I'd try to store reasonably cool but not freezing.

However, in terms of helping the yeast clean up after itself could putting it straight into cool storage slow it down? Should I ideally put it somewhere warmer for a bit to help that happen, even though I don't prime?

Cheers
kev

[Kev888]

Well no takers it seems, but an answer on another forum and further poking around has suggested that the yeast will clean up after itself in say a week if its reasonably warm, and (as you'd imagine) that it does so better when there's more of it still in suspension too. So a warm week post-primary and pre-chill/clearing sounds like the optimum time.

Cheers
kev

[gregorach]

I generally warm up the primary by a few degrees once it's within a couple of SG points of final gravity (I generally ferment quite cool). You really want to do your rest whilst the yeast is still fully active.

[gregorach]

Oh, and its technically known as a "diacetyl rest"...

[Kev888]

Ah, thanks for that. For some reason whilst i knew about the mopping up bit (without understanding anything very specific) i've always associated the concept of diacetyl rests specifically with lagering - but on reflection I don't really know why.

Funny really, you can plod along through the same old motions for decades without actually putting 2 and 2 together.. I guess I've not really had any flavours that I'd associate with dyacetyl or I may have put a bit more effort into understanding it, but then until the last year or so I've not had the facilities to cool either FV or keg so it probably sorted itself out naturally in any case..

Cheers
kev

[WishboneBrewery]

I'm not sure if this answers your question but this is how we do it at work.

Pitch yeast at approx 17c.
Ferment until Chill Gravity (which is about 1 point above FG) by this time the fermenter can be upto 24c having risen during fermentation.
Once Chill Gravity reached we chill the fermenter to 17c (I believe this is the Diacetyl rest where the yeast mops up its by-products).
After 24 hours we chill further to 13c
After a minimum of 24 hours more we transfer the beer to a conditioning tank where it is held at cellar temperatures 10-12c
Beer is casked and kept at cellar temps until delivery.

[Kev888]

Hmm, thats interesting; its a much shorter period of time than i'd imagined for the rest - probably I've been doing it by accident already then, as I rarely crash cool the instant fermentation ends. Albeit at around 20c still, although perhaps thats okay too - sort of mid way between Dunc warming it a little and you cooling it a little.

I do tend to crash cool much lower than 13C though - do you know if thats for clearing the beer or if it is another step in conditioning?

Many thanks,
Kev

[WishboneBrewery]

I need to learn the mechanics of it all, we used to chill further to 11c but have stopped to increase our yeast cell count in cask (not that we've had any problems, I think its just best practice). So yeah, its going to drop more yeast out and give you better clarity if you are bottling and not fining.

[Kev888]

Thanks!
I can't really understand why I never thought about all this before; time to start doing things more properly i think.

Cheers
Kev

[gregorach]

Hmm, thats interesting; its a much shorter period of time than i'd imagined for the rest - probably I've been doing it by accident already then, as I rarely crash cool the instant fermentation ends. Albeit at around 20c still, although perhaps thats okay too - sort of mid way between Dunc warming it a little and you cooling it a little.

I do tend to crash cool much lower than 13C though - do you know if thats for clearing the beer or if it is another step in conditioning?

Many thanks,
Kev

Remember, I ferment cool - I'm not a commercial brewer and I'm in no big hurry to free up my fermentor, and I'm not delivering casks for cellar conditioning. It's a completely different fermentation profile.

[Graham]

I suspect that in pdtnc's case, the clean-up goes on in the conditioning tank. It is the whole reason for the conditioning tank, although a lot more goes on than just diacetyl reduction. It is why I say in my books that bottled beer needs a week or two in cask before bottling, so that the necessary changes take place, and the undesirable volatiles generated during that process are vented off before the stuff is shoved into a tightly-sealed container like a bottle (or a Cornelius keg). It has been a contentious issue among people that seem to know better than me, but I stand by it.

I also suspect that the popularity of Doombar is more to do with their post-fermentation process than the recipe. They follow a similar procedure to that which pdtnc described, leave it in the conditioning tank for a minimum of a week (probably at a slightly higher temperature), then, presumably after venting the conditioning tank, they cask it. The casks then stay in their cellar for a minimum of a week before they let them out the door. By the time the stuff reaches my part of the world it has been shifted all the way from Cornwall, stood in a distributor's cellar for some time before delivery to the pub and hopefully the publican holds it for a few days and then vents it for a day or so before serving. By the time we get it, the beer has been preconditioned, and has had up to a month of maturation. It is virtually impossible for a publican to cock it up, as long as he leaves it long enough to settle; he certainly can't serve it green. The tendency these days for most of the pubco pubs to slap a cask-breather in the spile-hole immediately after knocking in the peg, before the volatiles have had a chance to escape, has been circumvented, so to speak, because the biggest part of this has already been done before casking.

I wonder what Coors will do to cock it up.

[weiht]

I usually pitch a little cooler around 18c and let it free raise to about 21-22c and hold it there for fermentation. Once the sg has stabalised, I then raise it to 24c for a day or two. Reason I'm doing it is because I used to get my fg a little on the high side and I tried rousing to no effect, I then tried to raise the temp and even without rousing the airlock activity starts bubbling again and the gravity does drop a few points at times. I use mainly Wyeast 1968 which likes to be a little warm to finish up, it also drops too early at times.

Later did I find out that raising the temperature at the END allows the yeast to finish up cleaning the beer of diacetyl and acetaldehyde, it's also a good thing to do with yeast that has a habit of dropping too soon and may not have attenuated fully. But do note that it's only best to do it at the end, say after day 5, as fermenting too warm at the start will produce fusel alcohols which can be a little hot.

[WishboneBrewery]

Just Thumbing through my 'Yeast - The practical Guide to Fermentation' book.

This paragraph is in regards to the yeast cleaning up and diacetyl (Page 69) "Stationary Phase (three to Ten days):

Our recommendation, especially to homebrewers, is to wait for the yeast to finish their tasks and clean up fermentation by-products as much as possible. <omit sentence> Wait until the yeast show no more activity, let the fermentor clear naturally, and then package the beer.

There is obviously a lot of reading in this book and I've only just started skimming through various parts.

[Kev888]

Thanks everyone for taking the time to post such considered thoughts; clearly I need to do a lot of reading! I've got Graham's book(s) and also the yeast book, but its been quite a while since I read the former and I'm struggling to get into the latter. Time for some revision!

Cheers
kev