Author Topic: unfermentable porter  (Read 884 times)

Offline goschman

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unfermentable porter
« on: October 07, 2014, 04:57:27 PM »
So I brewed a harvest porter recently with baked sweet potatoes, acorn squash, and sweet nugget squash in the mash. I originally undershot my mash temp and added the baked ingredients almost directly out of the oven. I noticed the mash temp rise to my intended temp in a few minutes however I foolishly didn't pay attention as the mash progressed.

All fermentation activity seemed normal but it has stopped in the mid 1.020s. The OG was around 1.054 from what I remember. My fear is that the mash temp rose above 158 which has severely limited attenuation. I roused the yeast and warmed the beer without any effect. I decided to pitch a pack of US05 yesterday without any luck either.

Any other thoughts other than too high of a mash temp? I haven't decided if I will keg the batch or dump it yet. I am contemplating re-brewing it however that will really mess with my schedule...
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Offline morticaixavier

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Re: unfermentable porter
« Reply #1 on: October 07, 2014, 05:13:33 PM »
have you performed a forced ferment test?

pull about a pint of beer and pitch a whole packet of us-05 and aerate the heck out of it. if that brings it down any you should be able to krausen the whole batch if you can get enough vigorous yeast cells in there (call the local brewery and beg a quart of slurry)
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Offline goschman

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Re: unfermentable porter
« Reply #2 on: October 07, 2014, 05:16:00 PM »
I have not tried that. Thanks for the idea.
On Tap/Bottled: Haze for Daze IPA, G Pils, Maibock, Kolsch, Summer Gold       

Fermenting: 
Up Next: Euro Pale, IPA

Offline goschman

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Re: unfermentable porter
« Reply #3 on: October 08, 2014, 03:21:47 AM »
Came home tonight to a continuous film covering the top of the beer. Must have become infected?
On Tap/Bottled: Haze for Daze IPA, G Pils, Maibock, Kolsch, Summer Gold       

Fermenting: 
Up Next: Euro Pale, IPA

Offline bboy9000

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Re: unfermentable porter
« Reply #4 on: October 08, 2014, 03:50:20 AM »
What does the film look like? Could you post a picture?
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Offline erockrph

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Re: unfermentable porter
« Reply #5 on: October 08, 2014, 12:42:49 PM »
So I brewed a harvest porter recently with baked sweet potatoes, acorn squash, and sweet nugget squash in the mash. I originally undershot my mash temp and added the baked ingredients almost directly out of the oven. I noticed the mash temp rise to my intended temp in a few minutes however I foolishly didn't pay attention as the mash progressed.

All fermentation activity seemed normal but it has stopped in the mid 1.020s. The OG was around 1.054 from what I remember. My fear is that the mash temp rose above 158 which has severely limited attenuation. I roused the yeast and warmed the beer without any effect. I decided to pitch a pack of US05 yesterday without any luck either.

Any other thoughts other than too high of a mash temp? I haven't decided if I will keg the batch or dump it yet. I am contemplating re-brewing it however that will really mess with my schedule...
Depending on how much of the veggies you used, maybe there wasn't enough diastatic power in the mash to convert everything fully?
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Offline dmtaylor

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Re: unfermentable porter
« Reply #6 on: October 08, 2014, 01:08:43 PM »
Throw in a pack or two of rehydrated Belle Saison yeast.  That should improve attenuation considerably.

Too bad if it got contaminated.  You could drink it up real fast if you like, but it sounds like you don't want to do that.  Keep your fingers crossed.  Maybe it will still turn out.  The odds do seem against it though.
« Last Edit: October 08, 2014, 01:10:30 PM by dmtaylor »
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Offline David Lester

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Re: unfermentable porter
« Reply #7 on: October 08, 2014, 02:40:20 PM »
It's possible that it fermented as it was supposed to. You have to take into account the viability of the yeast and the overall OG. My second thought is that you might have added so much sugar from the extra ingredients, the yeast couldn't get past 1.02. My third thought is that your grains may not have had enough time at the correct mashing temperature to convert all the starches to sugar.


Cheers