Author Topic: Controlling FG  (Read 930 times)

Offline SHILLA

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Controlling FG
« on: May 18, 2015, 04:55:40 PM »
Folks,

I'm wondering if brewers regularly
stop their fermentation or do they let it run its course?   For example, I recently
brewed an imperial ale that had an OG of 1.085.   After 10
days in the fermenter, it was down to 1.01 which put the
ABV much higher than I targeted (9.8%).     

I've not read anything on stopping fermentation but it seems
like something a brewer would want to do in order to hit
their numbers and control the flavor… and are there any downside
risks?   

The next question is when and how?   Is it as simple as taking frequent gravity
readings and when it hits the target… cooling the beer down
and letting the yeast drop out?




Offline HoosierBrew

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Re: Controlling FG
« Reply #1 on: May 18, 2015, 05:13:37 PM »
Bad idea IMO. For starters you'd be taking away the yeast's ability to 'clean up after itself', making yeast derived off flavors/aromas a likelihood (depending on strain).  And depending on your method of stopping fermentation, you'd be risking dangerous bottle bombs, too. Better to let any beer ferment out completely, and then make changes to your recipe (mash temp, grist, yeast strain) to finish higher in the future.
Jon H.

Offline pete b

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Re: Controlling FG
« Reply #2 on: May 18, 2015, 06:05:36 PM »
You can't exactly control FG, or at least you wouldn't want to artificially. I wonder about the grain bill for this beer. Is there some simple sugars in it? Is it close to 100% base malt?
I agree with Jon about the downside risk: your yeast won't clean up after itself. Also, you wouldn't be able to bottle because you would have to pitch more yeast but you don't know how much fermentables are left so there would be bottle bombs.
Don't let the bastards cheer you up.

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Re: Controlling FG
« Reply #3 on: May 18, 2015, 06:28:46 PM »
Wort sugar balance and yeast strain selection are better ways to control attenuation.

Offline erockrph

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Re: Controlling FG
« Reply #4 on: May 18, 2015, 06:32:52 PM »
Since yeast still clean up their metabolic byproducts (and reduce off-flavors) after fermentation is complete, it's not such a great idea to stop them before they're finished. Plus, I can't think of a style where it would be beneficial to leave the beer sweeter than the proper yeast would end up.

In the wine/cider world you would typically use sulfites & sorbates and/or repeated racking to bring fermentation to an early halt. For the reasons stated above, I don't know if that's a good idea for beer.
Eric B.

Finally got around to starting a homebrewing blog: The Hop Whisperer

Online jeffy

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Re: Controlling FG
« Reply #5 on: May 18, 2015, 07:32:28 PM »
Usually we write the final gravity number with an additional digit.  1.01 could be anywhere from 1.005 to 1.015, which is a good finishing range for most beers.  If you feel that you want this beer to have less alcohol you could add boiled and cooled water to it after fermentation is complete.  This way you get lower alcohol and the added benefit of more beer.
Jeff Gladish, Tampa (989.3, 175.1 Apparent Rennarian)
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Offline SHILLA

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Re: Controlling FG
« Reply #6 on: May 18, 2015, 07:38:23 PM »
Thanks for the comments.   That's all good input and it is clear you don't want to
halt fermentation prematurely.    Glad I asked!   

On a similar topic, if I move to secondary too soon, would that impact my attenuation?  I've read some
recipes where brewers move to secondary after 4 or 5 days and my beers are often
quite active at that time. 




Offline 69franx

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Re: Controlling FG
« Reply #7 on: May 18, 2015, 07:47:23 PM »
Yes, do not rack to secondary at that time. It really can only cause problems racking that early
Frank L.
Fermenting:
Conditioning:
In keg:
In Bottles:  
In the works: Hopefully brewing 10 gallons of Pilsner tomorrow for a family reunion in July, then back to IPA and  a barleywine to age

Offline pete b

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Re: Controlling FG
« Reply #8 on: May 18, 2015, 07:52:07 PM »
Thanks for the comments.   That's all good input and it is clear you don't want to
halt fermentation prematurely.    Glad I asked!   

On a similar topic, if I move to secondary too soon, would that impact my attenuation?  I've read some
recipes where brewers move to secondary after 4 or 5 days and my beers are often
quite active at that time.
For most beers you don't need to move to a secondary at all and certainly not after a few days. If the beer is not a high gravity beer that is going to be bulk aging for months there is no need to rack into secondary. If you are dry hopping or adding fruit it may be a good idea to rack onto those ingredients in a secondary but only after your primary fermentation is done which you will know by checking gravity a couple days apart and the gravity doesn't change. Racking off the yeast cake before primary fermentation may stall or end your fermentation prematurely and will likely end in off flavors like diacetyl for the same reasons mentioned above warning you off artificially ending FG.
Don't let the bastards cheer you up.

Offline klickitat jim

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Re: Controlling FG
« Reply #9 on: May 18, 2015, 10:45:36 PM »
As far as I can find on the inter webs, the reason so many recipes say to rack to seconday is to avoid autolysis, aka yeast dying and rupturing therefore spilling nasties into the beer. That generally seems to start happening somewhere around a month after they have finished fermentation. Some strains its much longer.

Offline The Professor

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Re: Controlling FG
« Reply #10 on: May 19, 2015, 03:58:40 AM »
Yes, do not rack to secondary at that time. It really can only cause problems racking that early
Not so sure about that...I routinely rack to a secondary carboy after five days or so (and if using my 'house' yeast, even less when making  standard or 'session'  strength beers) and I  then let things finish out for a long as it naturally takes.  That method still gives me better results than any of the the other procedures I've tried.  It sometimes takes a little longer (especially for the stronger brews) but I'm in no hurry if the end product turns out better.

It's just a matter of personal preference, of course, arrived at after trying different ways.  And there is no right or wrong way.

It's been said a thousand times, but bears repeating: it's best to experiment with different methods and decide which gives you the best result, rather than take anyone's word for it.t.
AL
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Homebrewer since July 1971

Offline pete b

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Re: Controlling FG
« Reply #11 on: May 19, 2015, 11:21:53 AM »
Yes, do not rack to secondary at that time. It really can only cause problems racking that early
Not so sure about that...I routinely rack to a secondary carboy after five days or so (and if using my 'house' yeast, even less when making  standard or 'session'  strength beers) and I  then let things finish out for a long as it naturally takes.  That method still gives me better results than any of the the other procedures I've tried.  It sometimes takes a little longer (especially for the stronger brews) but I'm in no hurry if the end product turns out better.

It's just a matter of personal preference, of course, arrived at after trying different ways.  And there is no right or wrong way.

It's been said a thousand times, but bears repeating: it's best to experiment with different methods and decide which gives you the best result, rather than take anyone's word for it.t.
What are the better results that you get from racking into a secondary after 5 days?
Don't let the bastards cheer you up.

Offline troybinso

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Re: Controlling FG
« Reply #12 on: May 19, 2015, 02:05:03 PM »
Yes, do not rack to secondary at that time. It really can only cause problems racking that early
Not so sure about that...I routinely rack to a secondary carboy after five days or so (and if using my 'house' yeast, even less when making  standard or 'session'  strength beers) and I  then let things finish out for a long as it naturally takes.  That method still gives me better results than any of the the other procedures I've tried.  It sometimes takes a little longer (especially for the stronger brews) but I'm in no hurry if the end product turns out better.

It's just a matter of personal preference, of course, arrived at after trying different ways.  And there is no right or wrong way.

It's been said a thousand times, but bears repeating: it's best to experiment with different methods and decide which gives you the best result, rather than take anyone's word for it.t.

Hmm. Sounds like a job for the Brulosopher!

Offline dilluh98

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Re: Controlling FG
« Reply #13 on: May 19, 2015, 02:38:59 PM »
Perhaps you meant an "early rack to secondary" experiment but Brulosopher has already done one experiment regarding primary-only vs secondary:

http://brulosophy.com/2014/08/12/primary-only-vs-transfer-to-secondary-exbeeriment-results/

Offline HoosierBrew

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Re: Controlling FG
« Reply #14 on: May 19, 2015, 02:55:02 PM »
What are the better results that you get from racking into a secondary after 5 days?

My question, too. Seems like a recipe for a higher FG and/or yeast byproducts.
Jon H.