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**Josh** · 12-21-2011, 01:44 PM

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

**Josh** · 12-21-2011, 01:46 PM

Also - I did make my starter using goya malta (experiment)...I had a pretty decent slurry though - so it seemed to work okay.

**Josh** · 12-21-2011, 02:37 PM

OR - is there any charted information for mash temps effects on final gravity?

***Yooper*** · 12-21-2011, 02:41 PM

Quote:

Originally Posted by Josh

OR - is there any charted information for mash temps effects on final gravity?

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.

**NordeastBrewer77** · 12-21-2011, 02:42 PM

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.

**Josh** · 12-21-2011, 02:50 PM

Quote:

Originally Posted by Yooper

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.

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?

**Josh** · 12-21-2011, 02:59 PM

Quote:

Originally Posted by NordeastBrewer77

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.

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

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...

**Josh** · 12-21-2011, 03:48 PM

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

Piratwolf · 12-21-2011, 03:51 PM

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.

**Josh** · 12-21-2011, 04:47 PM

Quote:

Originally Posted by Piratwolf

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.

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"