Should chilling begin at 'final gravity'?

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guypettigrew
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Should chilling begin at 'final gravity'?

Post by guypettigrew » Sat Jun 23, 2018 8:46 am

Graham Wheeler's Beer Engine, and his water treatment calculator are my 'go to' sites when planning a brew day. The prediction of the OG of the finished wort is always pretty much spot on now I know the overall efficiency of my kit.

Beer Engine also gives a calculated final gravity. For example, the last brew had an OG of 1.052 with a Beer Engine predicted FG of 1.014.

The beer reached 1.014 after about four days. I know from experience the beer would continue to drop down to about 1.007 or less if left at fermentation temperature. The yeast is WLP 005, third use after an initial harvest several weeks ago.

Should the beer be chilled as soon as it reaches this so called 'final gravity'? Or should it be left fermenting until the gravity has fallen as low as it can go?

Thanks.

Guy

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Re: Should chilling begin at 'final gravity'?

Post by gr_baker » Sat Jun 23, 2018 8:55 am

It depends. I think most of us would probably leave it to ferment out. However, if you really want to stop the fermentation you could cold crash and use gelatine or some other fining agent to get as much yeast out of the beer as possible. But you would have unfermented sugars and some residual yeast that will lead to problems with over carbonation etc.

If this is a regular problem then I'd check your mash temperature to ensure it's not too low.

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Re: Should chilling begin at 'final gravity'?

Post by Jim » Sat Jun 23, 2018 8:56 am

I usually drop the temperature as soon as the gravity stabilises (i.e. when it remains the same - as near as I can measure - for a couple of days).

I believe the gravity of 'live' beer will always continue to fall for quite a while (months even), but very, very slowly as the yeast chomps on the larger sugar molecules.
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Re: Should chilling begin at 'final gravity'?

Post by Jim » Sat Jun 23, 2018 8:58 am

Just to add, I don't think it's possible in a home brew environment to control the mash to the extent required to have a consistent 'final gravity'. We pretty much have to take what we get, within a few points or so.
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Re: Should chilling begin at 'final gravity'?

Post by Robwalkeragain » Sat Jun 23, 2018 9:41 am

Once it's stable you should diacetyl rest first which will basically cover the time to ensure fermentation has completed too. After that yep, chiller on, aux finings in if using - currents will stir them - lots of trains of thought on dry hopping, but I add the day before fermentation completes so I don't have to disturb the protective head on us-05.
I would probably ignore beersmith FG's, think the main point is most home brewers aren't brewing the same recipe over and over so can't guarantee any consistency. With the same grist, mash temp and yeast every time it's pretty easy to get a good idea of an FG. at 69c with us-05 and 92% pale malt I consistently pull 72% attenuation out

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Re: Should chilling begin at 'final gravity'?

Post by Dave S » Sat Jun 23, 2018 10:19 am

It also depends on whether you are kegging/casking or bottling. I usually aim to cool and keg a couple of degrees above FG and allow the beer to drop the last couple of degrees in the keg to carbonate. But as Jim says you can't predict FG with absolute accuracy at the HB level, but you can vent the keg if there is excessive conditioning. I wouldn't use that technique if bottling though as you might end up with bombs.
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Re: Should chilling begin at 'final gravity'?

Post by guypettigrew » Sat Jun 23, 2018 1:29 pm

Thanks for the replies.

As Jim has said, the gravity will continue to drop while the beer is in the keg. There's still yeast in it and plenty of slow fermenting sugars to give it condition. I gave up priming my beers years ago, having discovered a few days in the keg gives plenty of time for the beer to condition.

This isn't a problem for me, it was more a question about best practice. Is it best practice to chill the beer and drop most of the yeast out at about the 1/4 gravity point? This is certainly the point at which the fermentation has slowed right down.

It's often suggested to leave a fermenting beer until the gravity's the same for two or three days. I'm at a loss to understand how that can happen. My beer continues to ferment right up until the last pint! It's a living thing. Mind you, Jim's post on this subject does point out that our ability to very accurately measure gravity is a bit limited!

Guy

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Re: Should chilling begin at 'final gravity'?

Post by Dave S » Sat Jun 23, 2018 3:00 pm

guypettigrew wrote:
Sat Jun 23, 2018 1:29 pm
Thanks for the replies.

As Jim has said, the gravity will continue to drop while the beer is in the keg. There's still yeast in it and plenty of slow fermenting sugars to give it condition. I gave up priming my beers years ago, having discovered a few days in the keg gives plenty of time for the beer to condition.

This isn't a problem for me, it was more a question about best practice. Is it best practice to chill the beer and drop most of the yeast out at about the 1/4 gravity point? This is certainly the point at which the fermentation has slowed right down.

It's often suggested to leave a fermenting beer until the gravity's the same for two or three days. I'm at a loss to understand how that can happen. My beer continues to ferment right up until the last pint! It's a living thing. Mind you, Jim's post on this subject does point out that our ability to very accurately measure gravity is a bit limited!

Guy
No, I try to avoid priming too, which is why I rack to keg at 2-3 points above (notional) FG. Bu you're right, the beer in most cases will continue to ferment very slowly for the life of the batch. That will be slowed even further if you can keep it at cellar temp the whole time.
Best wishes

Dave

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Re: Should chilling begin at 'final gravity'?

Post by ben034 » Mon Jun 25, 2018 8:29 am

You could try a forced ferment next time. Take a sample from the fermenter on brewday after adding yeast (large enough to be measured with a hydrometer) and put in a container (or flask if you have a stir plate). This should ferment out rapidly (aerate well and shake regularly / place on stir plate for fermentation) and should give you the FG long before the main brew has reached FG.

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Re: Should chilling begin at 'final gravity'?

Post by Aleman » Mon Jun 25, 2018 1:22 pm

Most commercials will do a FFT and if casking will 'stop' fermentation when the gravity is 2 points above that determined by the FFT.

personally I allow it to ferment to 'stability' then RAISE the temp (for ales) a few degrees to ensure complete fermentation and the yeast clears up after itself, then add finings and crash cool.

I don't prime my beer either, I'll artificially carbonate. YMMV, YOMV, :D

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Re: Should chilling begin at 'final gravity'?

Post by guypettigrew » Mon Jun 25, 2018 8:01 pm

?FFT?

Guy

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Re: Should chilling begin at 'final gravity'?

Post by Coffeeuk » Mon Jun 25, 2018 8:04 pm

Fast ferment test

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Re: Should chilling begin at 'final gravity'?

Post by guypettigrew » Tue Jun 26, 2018 7:50 am

Ah, thanks!

Guy

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Re: Should chilling begin at 'final gravity'?

Post by Kev888 » Tue Jun 26, 2018 6:16 pm

As these answers say, you can either chill at actual FG or somewhat before actual FG, depending on what you want to do wrt carbonation, priming etc. However, never automatically chill at 'predicted' FG as (at least with new recipes) this is only a guess and may mean nothing in reality; it is mainly useful for planning recipes beforehand.
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Re: Should chilling begin at 'final gravity'?

Post by tourer » Thu Jul 19, 2018 8:29 pm

I ferment for about a week then transfer to a secondary for 3 days-ish then add gelatin and (dry hops if needed) drop temperature to 1c for 3 days take a FG if it's around 1010 then bottle with priming sugar (5.65g per litre) in the bottling bucket.

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