extremely bad attenuation

[angryyoungman]

I made 2 batches of "big" beer, a barley wine and an imperial stout. I did nearly everything the same, but used a stepped mash for the BW but mashed @ 149 for the RIS (give or take a few degrees, but it stayed right around 150 quite well). The OG was 1.100 for the BW and 1.115 for the RIS. I aerated using the same basic method (through a strainer then shook it like hell) for both. I pitched the same yeast as well (US- 04), but the yeast pitched in the BW was newer, the yeast in the RIS was about a month old. The grain bills were relatively similar with the only major difference being 5% of the bill was lactose added to the RIS. I was hoping for a final gravity of at least 1.030 for the RIS, but after checking the hydrometer fermentation has stopped and FG of the Barley Wine was 1.023, but 1.045 for the RIS. This comes from 2 readings a week apart.
Now the Barley Wine recipe called for the addition of champagne yeast to dry it out, but I was happy with that FG, so I opted to toss it in the Stout instead and hope to dry out that 1.045. Week later, nothing.
I'm going for a last ditch effort of adding some yeast energizer to the stout, but idk if there is much else to do... So my purposes here are to try and find out what went wrong and what else might be done. The only differences were stepped mash vs constant, additional unfermentable sugar to the stout, old yeast versus new. I suppose all together these factors likely account for the massive difference... But is there anything left to be done? Or should i just be content and try to bottle my stout syrup?
My plan was to add coffee and vanilla bean to secondary in the stout. With a higher than average gravity of like 1.030 i figured i could cut it down a couple points with the edition of coffee and make a serious coffee stout. instead I have a beer that has another beer worth of sugar left in it... I may just have to cut my losses and hope that 1.045 isn't so cloyingly sweet i have to dump it...

 

[afr0byte]

Hopefully you used multiple packets of yeast for each of these beers? Also, did you mean US-05 or S-04?

 

[sptaylor70]

Starting at 1115 and finishing at 1045 puts your ABV at 9.2%. For S-04, that's about the end of the line. For a hypothetical "normal" 75% attenuation, you would get to 11.4%, and that's out of range for most brewing yeasts. You can try pitching Wyeast 1084 Irish (Guinness) to finish your beer. It should give you more of the same flavor profile as your S-04, and can tolerate up to 12% ABV (or more, according to some).

 

[angryyoungman]

They were both small batches using S-04, but yeah I used multiple packs and my pitch rates were on target. As for the adding more yeast wouldn't the champagne yeast have helped bring the FG down as it can withstand considerably higher amounts of alcohol than beer yeast in general? Also the Barley Wine used the same yeast and it got through to about 10% so i figured the Imperial Stout could too. Idk, what's done is done and maybe the yeast are content to be at 9%. It just sucks that they crapped out on this brew. I used S-04 on an IIPA and it powered through to 10% within a week so I was hoping it would do the same for 2 more batches. 2 outta 3 isn't bad though haha.

 

[Rambleon]

Since the lactose is 100% non fermentable I'm guessing that's what you're running into.

 

[g-star]

Very high gravity beers like these really need pure O2. The shake and pray method has its limitations, and combined with a low attenuating strain like S-04 its not surprising it ended up where it did.

 

[Smellyglove]

With shaking you're able to add about 8ppm of o2. I'm not sure what your big beer calls for, but I'm very sure 8ppm doesn't cut the cheese.

 

[angryyoungman]

Well... sounds like the aeration was probably the main reason. I can't imagine the lactose helped much, but I gave it a shot. I just don't have the money to shell out on an aeration stone or O2 right now, so it is what it is. I still wonder how the Barley Wine was able to go from 1.100 to 1.024 using the same yeast and same aeration. Even better it appears to still be falling, checked the other day and it looked like 1.022. At least one brew is spot on.

 

[Hopper5000]

Batch size and grain/extract bill would be helpful. I am thinking probably the lactose is contributing to some of that high FG. Also, the only times I have had issues with stalled out fermentations are with darker beers. I dunno why that is personally. However, you did two different beers using two different methods of mashing and you added some unfermentables to one so why are you surprised that you got different fermentation results? I wouldn't be since I did a different process for each... Another idea is to heat up the RIS to somewhere in the the low to mid 70's temp wise and that might kick the fermentation back into gear. If not you could try pitching a starter of something like wlp99 when it's at high krausen and that might do the trick for you.

 

[angryyoungman]

i'm not so surprised by the different results, just the extreme nature of the difference. I figured something like 1.030 would be reasonable for the RIS.
As for the grain bill it was as follows
4 lbs Pale 2- Row
2 oz roasted barley
12 oz crystal 60
8 oz chocolate malt
4 oz coffee malt
5 oz lactose and 2 lbs of DME added to the end of the boil
it's a 2 gallon batch, mashed at 149.
I've been fermenting at 70 degrees F partly because I don't have means to go much lower and partly because I thought a little higher temps might be better for better attenuation.
My yeast usually attenuates more than I anticipate, but this guy is just not cooperating.
I'm thinking that the mash combined with the unfermentables, and aeration are the cause. I doubt it's one easy issue. If it were aeration then one would think that using the same aeration technique (or lack thereof) would produce higher FG in my previous batches, but it really hasn't. I'm not certain, but I doubt that the unfermentables are really so high as to have a 1.045 FG, and if the ABV was too inhospitable for the S-04 then the champagne yeast should have had no problem finishing the job as it is suitable well above 15%. In combination though, poor aeration + big brew + different unfermentables + high ABV = high FG. IF anyone has any other theories I'll gladly hear them, but I think I just overlooked several "small" variables that made for a big mistake.

 

[kaconga]

Did you rehydrate the champagne yeast? You might have killed off more than you realize if you hadn't.

 

[angryyoungman]

Nope. Not at all. That's definitely a sign of an amateur haha. Said to pitch it as is, tossed it in.

 

[Hopper5000]

If you are pitching dry yeast into something that has alcohol it's a good idea to rehydrate it to prevent most of it dying from osmotic shock.

So looking at your grain bill the 5oz of lactose in 2 gal batch should only contribute about 6 unfermentable gravity points. It does look like your dark grains are a bit high. Grain wise your at about 27% "unfermentables". I put that in quotes because some of the sugars are fermentable but just not as much as grains that have the ability to convert themselves. Anyways, with that and the lactose you are looking at about 33% of your grain bill as unfermentable grains. That may be why your FG is so high and the champagne yeast didn't do anything.

That being said you might have a stuck fermentation for the reasons you have stated. It can be hard to tell. Have you taken a sample and tasted it? Does it taste worty or cloyingly sweet?

Another question is how much yeast are you pitching in this 2 gallon batch? It is quite hard to overpitch on a homebrew scale but with a 2 gallon batch it may be possible. If that's the case then it might be why your having some difficulties. Overpitching can cause issues too.

 

[angryyoungman]

I'm not sure how you got 33% of the grain bill as unfermentable... Are there unfermentables in 2-row? I get almost exactly 75% fermentable to 25% unfermentable, but if you could show me how you are doing it I would be very appreciative. I pitched one pack of dry yeast, i suppose that could have actually been over pitching. My thought process was that it was a big beer and the yeast had been in my fridge for about a month, so it would probably be right on the money.
As for taste, it tastes almost like a malty espresso. There's a lot of roasted flavors and a lot of coffee, but a sweet malty backbone. It isn't terrible though. I'm a big fan of "malta" or "maltzbeir" and it is reminiscent of that, but a little less sweet. Certainly not cloyingly to my tongue, but it is perhaps worty. Then again this is at 70 degrees and uncarbed. I worry that it could either taste terrible carbed cooler, or it could explode due to fermentation restarting in the bottle.

 

[Hopper5000]

One packet shouldn't be drastically overpitching. You could plug it into calculators. From my calcs you have 95oz in your bill (including lactose). 31 of that is unfermentable (including lactose) 31/95 is about 33%. If you take out the lactose it's 26/90 which is about 28%. Is my math wrong? I apolagize if it is...

If it tastes good then I would just let it be. You could take it off the yeast and secondary it for a while if you wanted too. Letting it sit like that vs the bottle might prevent bombs and/or allow it to keep fermenting a bit.

 

[Hopper5000]

Another option is to brew a really dry stout and blend the two together.

 

[angryyoungman]

Your math is right, but do you include the 2 lbs of DME in the calculation or is that left out? If so, there's 75.6% fermentable versus 24.4% unfermentables. I planned on putting it in secondary anyway, it's going onto some vanilla bean and cuban coffee (i've named it the Soviet Bloc Stout). I like the idea of adding a really dry stout. I want a strong coffee flavor though so I have to wonder how I might make a dry stout that doesn't take away from the coffee. Maybe do a small batch that's nothing but 2- row and a little bit of de-bittered black malt (for color) and a small portion of coffee malt to keep some coffee flavor? Then a really strong yeast to make sure it's very dry like WLP007? What would I do about hops though? I used Willamette to bitter the RIS, just stick to that? One addition of Willamette at the beginning of the boil?

 

[Hopper5000]

Ya you are right, I did leave out the DME, mybad. One thing I forgot to ask was, do you know if your thermometer that you used to measure the mash is accurate. I had one of mine get funky and I ended up mashing about 6 degrees lower than I though I was... really dried out the pumpkin beer I was making.

I think you are on the right track with a second beer. wlp7 or wlp99 would do the trick to really dry it out. If you are just trying to make something really nautral then your recipe sounds alright. Just don't dilute down the flavor too much.

Hops decision at the beginning sounds good. RIS's aren't really about the hops and they are meant for aging so the hop flavor tends to dissipate.

 

[angryyoungman]

Yeah I use a really good digital meat thermometer which is near perfect, if anything I noticed I had a harder time getting the mash temps to stay high enough. There were times it dropped to like 145, but I would expect a more dry beer. Right now it's in secondary and when I get around to it I'll make that dry stout, blend them, and let it age and calm down a bit. Heck, this way I'll get even more beer

 

[Hopper5000]

Cool, good luck and I hope it works out!