Oatmeal Stout Woes

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kirblator

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I tried to brew Yooper's Oatmeal Stout which went fine until the fermentation process. The batch came through the brewing process with an OG 1.056, a little high but I also only collected 4.5g on a 5.0g batch. I pitched rehydrated US-05, as I always do, but this time I added yeast nutrient and energizer to my wort. I did this because I had leftovers from a batch of Skeeter Pee and figured it wouldn't hurt. After two weeks I checked the gravity of the Oatmeal Stout and it read 1.032. There was no signs of krausen so I checked my hydrometer in water to confirm it was reading 1.000, and it was. I resealed the fermenter and gave it a gentle swirl and did that once to twice a day for two more weeks. I checked the gravity again, 1.032 giving my an abv of 3.2%. Since the FG was stable for 2 weeks I went ahead and bottled the batch but I am very dissapointed Beersmith calculates my efficiency to be 63%, I plan for 65%, and my attenuation to be 41.5%, which is horrible. I mashed at 156F so i did expect to extract some non-fermentables but not quite this much. What caused this horrible experience and would you even let the beer carbonate?
 
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I think you're confusing efficiency with attenuation. Efficiency is how well you get the sugars out of the grain. This number is calculated before you add the yeast.

Attenuation is how far the yeast ferments the sugar. For example, if you started with 1.060 and ended with 1.015, you'd have 75% attenuation ( 60-15 / 60). I don't believe Beersmith attempts to calculate this at all, but it might tell you the expected attenuation of the yeast - that's straight from the yeast manuf. The attenuation depends on the fermentability (potential gravity) of each grain in the recipe, and also on your mash time and temperature. To a lesser extent, things like pH can play a factor, but not a big one. You probably know much of this, but my fingers are going so I figured I'd spell it out.

I would not bottle that beer. I had a similar experience with an Oatmeal Stout once - it finished right where your's did. I assumed that my mash was messed up, so I added additional enzymes to the fermentor and bingo it finished fermenting. See the following link for more information on that:

Escape from Stuck Fermentation Mountain - AE to the Rescue!
 
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kirblator

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Thanks for the link for the amylase enzyme, wish I would have known about that before I bottled my beer. The problem I am faced with now is should I pour all my beer back into a fermenter and treat with amylase enzyme or is there no saving this beer?
 

North_of_60

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Thanks for the link for the amylase enzyme, wish I would have known about that before I bottled my beer. The problem I am faced with now is should I pour all my beer back into a fermenter and treat with amylase enzyme or is there no saving this beer?
I don't think it would hurt anything at this point to pour it back into the fermenter. I would give it a try.

I have had two batches that didn't bottle carbonate because I screwed up the bulk priming. I poured them into a bucket and transferred them to a keg. I probably oxidized the heck out of them but they were two of the best tasting beers I have made.
 

rhys333

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Now I'm thinking I should check the gravity on my oatmeal stout. It fermented for 1.5 days and put out a wimpy 1/2" thick krausen, then flatlined. I used WY1968, which I know has a tendency to drop out so I've been gently rousing the yeast. I've been going on the assumption that it's just quietly doing it's thing, but maybe not.
 
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kirblator

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@North_of_60 Thanks for the insight with your experience. I suppose to save this batch and prevent potential bottle bombs I will give it another go.

@rhys333 Yeah, it might be worth checking in on, I assumed mine was chugging away slowly as well but it appears it was not...

Also should I re-pitch yeast or just let the residual yeast do their job?
 

LittleRiver

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It's a good beer, and you're almost there, so I would agree that it's worth trying to save. Gently pour it back into a fermenter, and try the enzymes and/or more yeast.

I'm drinking a batch of the same recipe right now. Like you, I mashed at 156F. My OG was 1.062. I pitched a 3 month old slurry of Wyeast 1450 from a previous brew, and left it in primary for 2 1/2 months. FG was 1.011. It's a nice beer for these cold evenings.
 

rhys333

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@North_of_60 Thanks for the insight with your experience. I suppose to save this batch and prevent potential bottle bombs I will give it another go.

@rhys333 Yeah, it might be worth checking in on, I assumed mine was chugging away slowly as well but it appears it was not...

Also should I re-pitch yeast or just let the residual yeast do their job?

False alarm on mine, I guess. 1.053 -1.012, or 76% attenuation as of this evening. Wyeast claims only 67-71% on their website, but clearly it's all liesssss!

Tastes good though.
 

gwinn758

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If you still have a problem with it check your thermometer. Had an IPA lately that acted the same way and couldn't figure it out. Way under attenuated and had a muted taste. I could not figure it out and then I decided to check my brewing thermometer against one I knew was spot on. I believed I had mashed in at 151 when I actually mashed in at approximately 164. I now calibrate my thermometer before every brew.
 
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kirblator

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If you still have a problem with it check your thermometer. Had an IPA lately that acted the same way and couldn't figure it out. Way under attenuated and had a muted taste. I could not figure it out and then I decided to check my brewing thermometer against one I knew was spot on. I believed I had mashed in at 151 when I actually mashed in at approximately 164. I now calibrate my thermometer before every brew.
Absolutely could be a factor, I ordered a ThermaPen so I can be more confident in my mash temps. Thanks for the advice!
 
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kirblator

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Update: I unbottled the beer, added amylase and repitched a sachet of US-05 yeast and let sit for two weeks. I took an FG reading again and 1.032, just as before. I figured fermentation must be done and bottled the beer. I'm going to let it carb up and see if it tastes any good but at 3.8% abv i can't imagine this being anywhere near drinkable with 1.032 FG. Any more insight as to what could have went wrong?
 

SanPancho

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Too many unfeementables. its long chain sugars from mashing too high.

Amylase doesn’t affect them once they’re developed. Us05 dont eat em.

If you wanna know for sure, get a little bit of brett yeast and add it to a bottle. Put a ballon on te bottle and see what happens. Brett can eat the “unfermentables” so if the ballon expands then theres your answer. Many British dark beers often had brett secondary aging, it might be delicious.
 
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