Made changes and last 2 batches won't go below 1.030!

[D_Nyholm]

I recently brewed 2 separate batches of Oatmeal Stout a week apart. Both of them are now stuck at 1.030. There were a few changes that I made with my procedure but I do not see how they would have affected it this much.

1.) Mashed too high. I mashed around 160 since i had a new thermometer that I did not calibrate before use. I could see this adding to the FG, but I do not know if it should have been that much.

2.) Grind my own grains. I purchased a monster mill and ground my own grains. I left the settings alone and I had A LOT of powder so I think the teeth are too close together. I also got a lot of trub afterward which I believe is from this.

3.) Did not use PH 5.2 stabilizer. I also did not check my PH at all, but I did a full volume (almost 8 gallons) BIAB and the recipe came out at 1.058 for both which was almost 80% efficiency. I was getting 70% before with store ground grains.

I did just place an order for amylase as I have already tried to rouse the yeast, added yeast energizer and nutrient, and raised the temp to 72 (I fermented right around 66). I did re-pitch a 1L starter of Nottingham a week or so ago and nothing happened.

I'm open to suggestions. Thanks in advance.

 

[shawnbou]

FG for an Oatmeal Stout is normally 1.010 - 1.018 so you're about 12 points higher than what's "normal". I suspect a combination of factors.

Mashing at 160 will most certainly result in a less fermentable wort, leaving you with a higher FG than you expected.

Overmilled grains could lead to more extraction, but you'd have seen a higher OG on your wort when you started. What was your planned OG and what was your measured OG?

The only other thing I can think of is what kind of oats you used. Did you use rolled oats, flaked oats or similar? If you used regular old oats (not rolled/flaked) you're supposed to do a cereal mash to gelatinize the starches before the saccharification mash ... not doing so would leave you with a lot of starch in your wort that will not ferment and leave you with a higher FG.

 

[Golddiggie]

Mashing at 160F will give it a FULL body (high FG). Normally you mash in the range from 148-158F (lower for thinner body, higher for fuller body). Adding more yeast won't help you much, if at all. Without knowing your normal PH range, without stabilizer, it's hard to say, but I doubt that has much to do with the FG. Higher efficiency shouldn't throw the FG off that far, depending on the attenuation level of the yeast, and the OG. I don't think Nottingham would have any issue going through the fermentable sugars in the wort. The problem is, you have so many non-fermenting sugars in the wort.

You could try using some beano in the batch at this point. Look up the threads of people using it to help drop the FG. The amylase might have the same effect. I've never needed to use either in my batches.

 

[Yooper]

#1 is the likely culprit. An oatmeal stout, at least mine, finishes at 1.018 or so. I mash pretty warm (156 normally) for that beer. But if I mashed a bit warmer, I know my FG would be much higher. If I mash below 152, my beers finish under 1.010. So I"ve found my sweet spot for my system. Everyone's is a bit different, though. I'd probably mash at 154 or so if I had issues with underattenuation.

Of course, other things go into attenuation as well. The other big one is the recipe as some recipes have more complex sugars while some have simple sugars, and that affects the attenuation quite a bit. Yeast is the other biggie. Over/underpitching and yeast strain attenuation %s are a big part of attenuation.

I don't think mash pH will affect attenuation much- just flavor and efficiency.

 

[tre9er]

Try one teaspoon of the amylase, then check gravity in 3-5 days.

 

[D_Nyholm]

It actually was Yoopers recipe! Supposed to be a starting gravity of 1.052 and a f.g. of 1.016-8 so I got a little more out of it. I also used just standard flaked oats from Austin homebrew and I did not run.them through the mill, just mashed as is. Could that be a oroblem? At this point, i am going to just use the amylase and hope that i can save these two. I am hoping i can figure out what went wrong as i plan on making this recipe regularly. I have also made it in the past with no problems.

 

[tre9er]

It actually was Yoopers recipe! Supposed to be a starting gravity of 1.052 and a f.g. of 1.016-8 so I got a little more out of it. I also used just standard flaked oats from Austin homebrew and I did not run.them through the mill, just mashed as is. Could that be a oroblem? At this point, i am going to just use the amylase and hope that i can save these two. I am hoping i can figure out what went wrong as i plan on making this recipe regularly. I have also made it in the past with no problems.

Just take my advice and use the enzyme sparingly. Otherwise you'll end up with 1.002 alcohol.

 

[D_Nyholm]

Just take my advice and use the enzyme sparingly. Otherwise you'll end up with 1.002 alcohol.

Yeah. I've read up on it and I plan on taking time and going a few drops at a time. I would rather 1.020 than 1.010!

 

[Hjekk]

I have a similar question as D_Nyholm, however I am fermenting a scotch ale kit by brewer's best. The kit had a pretty low expected OG of 1.034-1.038. This seemed rather low to me for a scotch ale, so on the advice from my home brew store I added 3.3lbs of LME to the kit. The kit already included 3.3lbs of LME and 1lb DME with about 1lb of mixed grains.

My OG after the boil was 1.064, which made me very happy! It's been about a week and a half in the fermenter with no airlock activity for the last 2 days. I checked the the gravity this evening and found that it was 1.022.

Before the addition of the extra LME, the kit estimated the FG to be 1.010-1.014. Is 1.022 a reasonable FG with the added sugars or do I have an incomplete fermentation?

Should I bottle the beer now, transfer to a secondary and wait, or repitch?

 

[Yooper]

I have a similar question as D_Nyholm, however I am fermenting a scotch ale kit by brewer's best. The kit had a pretty low expected OG of 1.034-1.038. This seemed rather low to me for a scotch ale, so on the advice from my home brew store I added 3.3lbs of LME to the kit. The kit already included 3.3lbs of LME and 1lb DME with about 1lb of mixed grains.

My OG after the boil was 1.064, which made me very happy! It's been about a week and a half in the fermenter with no airlock activity for the last 2 days. I checked the the gravity this evening and found that it was 1.022.

Before the addition of the extra LME, the kit estimated the FG to be 1.010-1.014. Is 1.022 a reasonable FG with the added sugars or do I have an incomplete fermentation?

Should I bottle the beer now, transfer to a secondary and wait, or repitch?

A 1.020 FG is reasonable with an extract batch, especially with that much extract, so you're not far off. I'd wait about 5 more days, and then go ahead and transfer. Sometimes transferring "wakes up" the yeast and you'll get a few more points. Of course, sometimes transferring stalls it permanently, so it's good to make sure it's not going any lower where it is first.

 

[Yooper]

It actually was Yoopers recipe! Supposed to be a starting gravity of 1.052 and a f.g. of 1.016-8 so I got a little more out of it. I also used just standard flaked oats from Austin homebrew and I did not run.them through the mill, just mashed as is. Could that be a oroblem? At this point, i am going to just use the amylase and hope that i can save these two. I am hoping i can figure out what went wrong as i plan on making this recipe regularly. I have also made it in the past with no problems.

No, that's not a problem. I never mill my flaked grains.

I think the issue is the high mash temp. If your thermometer is even off by say, two degrees, you could have a real problem if you showed a mash temp of 160.

My thermapen is highly accurate, but I would never push it and mash above 158 for my system, and even then I'd be watching the grainbill and the temperature!

 

[Hjekk]

Thanks for the fast reply! I suppose I do just need to be a bit more patient.

I did have a thought though, what if I transferred my batch to a secondary and added a few ounces corn sugar. Would that "wake up" the yeast a bit by giving them more food or just prolong fermentation unnecessarily?

 

[unionrdr]

It wouldn't help much at all. Swirl up some yeast & warm it up slightly. My Burton ale started at 1.065,got it down to 1.017 doing that.

 

[D_Nyholm]

Added 1/2 teaspoon of amylase on Thursday and it was bubbling away nicely with 12 hours. Going to check gravity sometime this week and hope it didn't ferment too far. Though I don't think that 1/2 teaspoon will drop it too much. I will probably have to add more but I prefer the idea of a too sweet stout than a too dry one!

 

[D_Nyholm]

Added 1/2 teaspoon of amylase on Thursday and it was bubbling away nicely with 12 hours. Going to check gravity sometime this week and hope it didn't ferment too far. Though I don't think that 1/2 teaspoon will drop it too much. I will probably have to add more but I prefer the idea of a too sweet stout than a too dry one!

Just an update. The 1/2 teaspoon brought both carboys from 1.030 to 1.014. A little drier than the recipe called for but I'll take it. Both samples tasted great and I am going to let it sit for a few more days before I keg it and let it keg condition for 3 weeks

 

[tre9er]

Just an update. The 1/2 teaspoon brought both carboys from 1.030 to 1.014. A little drier than the recipe called for but I'll take it. Both samples tasted great and I am going to let it sit for a few more days before I keg it and let it keg condition for 3 weeks

Excellent info. Glad you came out

 

[Beef_Supreme]

Glad to see it worked out.