stuck fermentation or high temp mash result?

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Josh

Josh

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Hey guys...I REALLY didn't want to post yet another "is my beer ok?" thread, but here it goes.

Brewing Yooper's Oatmeal Stout recipe, had some slight modifications (some intentional, some a result of a couple pre-brewing baltic porters) Mashed at 158. OG 1.060. I made a 2L (stepped once - so 2L, decanted, 2L) starter from a slightly older (October 2011) Wyeast 1084 and added to fermenter 2 weeks ago.

Fermentation took off pretty quickly. I took a gravity reading 5 days ago - 1.025. Took another reading yesterday and it's still 1.025. The ambient temp has been between 64 - 66.

BTP is saying FG should be around 1.018 - could the 7 extra points be the result of a higher mash, a poorly attenuating (59% as opposed to 70%) or did the yeast completely crap out early?

thanks for your thoughts
 
Also - I did make my starter using goya malta (experiment)...I had a pretty decent slurry though - so it seemed to work okay.
 
OR - is there any charted information for mash temps effects on final gravity?
 
Josh said:
OR - is there any charted information for mash temps effects on final gravity?
Click to expand...

I've never seen a chart like that- but it's a good idea if it is possible to predict. I think that it's hard to predict FG for others. In my case I know my system and I'm pretty sure what a mash temp of 158 will give me, but yeast attenuation and other ingredients play a huge role as well. Crystal malt will give a different amount of body and residual sugars to the beer as opposed to flaked maize, for example.

The last time I made this recipe, I used Denny's Favorite 50 (Wyeast 1450) and it finished at 1.021.
 
Higher mash temps mean more unfermentable sugars in the wort, resulting in a higher FG. Not sure about the stuff you made your starter with, I use good ol' DME in my starters. I'm guessing it's a mash temp issue, 158 is a bit high.
 
Yooper said:
I've never seen a chart like that- but it's a good idea if it is possible to predict. I think that it's hard to predict FG for others. In my case I know my system and I'm pretty sure what a mash temp of 158 will give me, but yeast attenuation and other ingredients play a huge role as well. Crystal malt will give a different amount of body and residual sugars to the beer as opposed to flaked maize, for example.

The last time I made this recipe, I used Denny's Favorite 50 (Wyeast 1450) and it finished at 1.021.
Click to expand...

that's a little more encouraging - thanks!

I kept the grain bill the same - my boil ran a little longer, which is where my higher gravity came from. I stirred up the yeast and have been rotating out some hot water bottles...maybe that'll get a few more points down if there's any fermentable left?
 
NordeastBrewer77 said:
Higher mash temps mean more unfermentable sugars in the wort, resulting in a higher FG. Not sure about the stuff you made your starter with, I use good ol' DME in my starters. I'm guessing it's a mash temp issue, 158 is a bit high.
Click to expand...


yeah, I was going for something a little north of motor oil consistency. :D

I usually use DME, but I've read about guys using malta on other sites with pretty consistent results. Assuming the problem isn't the starter and it's just coincidence, the "malta as starter" worked pretty well. It was SUPER easy - basically 4 bottles of malta and then 2 bottles of distilled water gave me about 2.2L of 1.040 wort - I didn't boil it, so it took about 2 minutes to make...

...of course, I've never had a problem meeting my numbers before either...
 
I THINK I've found an answer...and it' been sitting on my desk all along. According to Palmer, around 158 the Apparent Attenuation Limit sort drops off the table - which, in his example - happened to affect FG by 6 points. Obviously there are a number of factors which would make it hard to say "X degrees add/subtracts Y SG points", but between his chart (Figure 93 in the book) and discussion on the previous page (regarding higher temps denaturing beta amylase among others), I think I'm okay to go.

Thanks for your thoughts Yooper & NordeastBrewer77
 
I don't think you should worry about posting these things. After all, it'd be a pretty empty forum and the rest of us wouldn't learn nearly as much! Plus, you did things like take gravity readings and give your recipe and info :)

I've heard of people using Goya to culture yeast harvested from bottles, so from my (admittedly limited) understanding of yeast I don't see why your process wouldn't work. Mr. Malty's charts gauge yeast viability by age/length of storage, so my first suspect would be the slightly older yeast you mentioned.

All that said, high mash + crystal malts = high FG and for what you were attempting I don't think 1.025 is out of range much at all. If you want to shave off a few more points, I'd suggest moving the fermenter to about 70 degrees and MAYBE gently rousing the yeast.
 
Piratwolf said:
I don't think you should worry about posting these things. After all, it'd be a pretty empty forum and the rest of us wouldn't learn nearly as much! Plus, you did things like take gravity readings and give your recipe and info :)

I've heard of people using Goya to culture yeast harvested from bottles, so from my (admittedly limited) understanding of yeast I don't see why your process wouldn't work. Mr. Malty's charts gauge yeast viability by age/length of storage, so my first suspect would be the slightly older yeast you mentioned.

All that said, high mash + crystal malts = high FG and for what you were attempting I don't think 1.025 is out of range much at all. If you want to shave off a few more points, I'd suggest moving the fermenter to about 70 degrees and MAYBE gently rousing the yeast.
Click to expand...

Thanks Piratewolf!

So - I just heard back from a "yeast guy" at a microbrewer I do some work for and he said the same thing I found in Palmer's book. His words, "At 158* beta amylase (makes the sugars for the yeast) is all but denatured (destroyed, for good), and the alpha amylase (makes both sugars for you and the yeast) is at its upward limit. 158 is still operational for your alpha amylase, but just barely, resulting in a thicker beer / higher Plato."

SO - it appears that this beer has named itself the all-too-clichéd "Quaker State Oatmeal Stout":ban:
 
How does it taste? I've had some fermentations that just never finished (hence my new focus on fermentation starters, temp, etc), and the beer kind of tasted "worty." A sweetness that wasn't sugary or even malty, but had a bit of that odd flavor of wort before you pitch.

Does it taste like a finished, if thick, beer, or does it still have those wort flavors?
 
ResumeMan said:
How does it taste? I've had some fermentations that just never finished (hence my new focus on fermentation starters, temp, etc), and the beer kind of tasted "worty." A sweetness that wasn't sugary or even malty, but had a bit of that odd flavor of wort before you pitch.

Does it taste like a finished, if thick, beer, or does it still have those wort flavors?
Click to expand...

the sample I tasted yesterday tasted great. The roastiness cuts any sweetness (but not overly roasty...kinda like a french or even italian roast coffee). It's thicker for sure, but I don't think it's significantly different than something more on target (which, according to beer tools should be around 1.018 at 70% attentuation anyway)

Of course...it's not carbed yet, but comparing against memory of other stout
"samples" I've done recently, I think this will be the best stout I've done in a while (it seems to be a solid recipe! Thanks for sharing with us, Yooper!)
 
Josh said:
the sample I tasted yesterday tasted great. The roastiness cuts any sweetness (but not overly roasty...kinda like a french or even italian roast coffee). It's thicker for sure, but I don't think it's significantly different than something more on target (which, according to beer tools should be around 1.018 at 70% attentuation anyway)

Of course...it's not carbed yet, but comparing against memory of other stout
"samples" I've done recently, I think this will be the best stout I've done in a while (it seems to be a solid recipe! Thanks for sharing with us, Yooper!)
Click to expand...

I am having this beer now. I mean, right now, at this moment! I mean, it IS after noon.

I love it. It's roasty, but not like "roast" that I dislike but instead a creamy coffee type of roast flavor. That's what I was going for- an after dinner stout- rich, creamy, full bodied, but not too sweet or too roasty. If that's what you were hoping for, I think you'll be happy with it even if the SG doesn't drop the last few points.
 
Yooper said:
I am having this beer now. I mean, right now, at this moment! I mean, it IS after noon.

I love it. It's roasty, but not like "roast" that I dislike but instead a creamy coffee type of roast flavor. That's what I was going for- an after dinner stout- rich, creamy, full bodied, but not too sweet or too roasty. If that's what you were hoping for, I think you'll be happy with it even if the SG doesn't drop the last few points.
Click to expand...

NICE! (I'm having a Founder's Scotch Ale...I find beer with lunch make for inspired afternoons)

Yes - that's EXACTLY what I'm looking for. I definitely got that roast flavor - I went with the pale chocolate and black barley - it really does taste more coffee-like than the bitter/char roast flavor I think I've been getting in the black patent additions. I want to bottle it tonight (now that I've convinced myself I won't be making bottle grenades)...but I have a feeling I might be kegging after Christmas (fingers crossed) and this would make an excellent keg-christener...so I may wait until Monday.
 
I thought I would throw in my two cents since I just finished up my keg of this beer a week go. The only change I made was to substitute roasted barley for the black malt (I think black malt would have been better). I also mashed a little lower and hit 155°F.

My terminal gravity was 1.021 with British Ale II (Wyeast 1335) yeast. I should also note the beer turned out awesome. I suspect after reading this thread that this particular recipe probably just has a lot of unfermentables floating around in it.

I will definitely be making this one again, particularly for people that like stouts with less roast intensity.
 

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