Brewed a RIS October 1 that had an OG of 1.105 and was supposed to finish around 1.030 per beersmith and double checked on brewgr. I mashed at 153 for 60 min, oxygenated appropriately, but believe I underpitched my yeast and fermentation stopped at 1.040. I warmed the fermenter, pitched an active starter, swirled the fermenter, added some simple sugars and after all of that I’m still at the same gravity reading. I would really like to bottle this stout but should I be worried that FG is too high? Keg instead? The stout has some unfermentables like a lb of lactose and some crystal malts but I assume this is all taken into account by the brewing software. Regardless, I’m still only sitting at 58% attenuation.
They stalled out apparently. Sounds like you are trying what should work. I've had this happen a few times. Simple sugars may be just that. Too simple. The kind of sugar it is could distract your yeast from the more complex stuff that is probably what is lurking under your SG at the moment and has them stumped. You may have fed them too much of the sugars that are easy for them to process and which distracted them from the complex ones. It's like hippy crack for them if you give them the wrong thing too early. They might kick through in a few weeks with the additional things you've done.. But, you could also repitch. Get some dry yeast and give a new crew a chance to finish up.
And if you want to bottle, cut the sugar in half and monitor. I have done this before with OK success.
I think kegging is a good idea with this. First of all, I've had to take aggressive actions when I bottled high ABV beers if I wanted them to be well-carbonated. It sounds like you have taken some aggressive action in the fermenter and it was ineffectual. I think bottling is going to be a crapshoot. You might get yeast to carbonate perfectly, by dumb luck. Or the yeast will fail (most likely, I think). Or the yeast will wake up, eat your bottling sugar, and possibly eat residual sugars leftover from fermentation and take you towards overcarbonation or even bottle bombs. I can't say how likely that is, but it is not a great outcome. Kegging should help you to dial in the carb levels as you like, safely.
@Drel you mentioned the mash time and length. What were the grain bill and yeast strain? Beersmith does not take grain bill into consideration when predicting attenuation. And some beers (e.g. many stouts) will never get near the Beersmith predicted FG. Let's figure out how big a problem you have before worrying about how to fix it. BTW, if you add a bit of simple sugar to a finished beer, and the yeast ferments it, FG will be practically the same as it was before. Also BTW, you're not at 58% attenuation, you're at 62%. (Or actually a little higher, since you added some sugars and they fermented out.)
Beersmith 3 properly considers lactose gravity contributions as unfermentable. I checked that out earlier and forgot to mention in my post. I'm not sure the previous versions treated lactose properly. At least, I remember encountering a program that didn't but can't recall for sure if it was when I was using Beersmith. As for grain fermentability, it calculates that an all crystal 60 and an pilsner malt grist with the same starting gravity would end the same. So it seems pretty different from conventional thought on fermentability of crystal malts.
That would be good. It's a start! From what I've heard, a previous (?) version (maybe 2? not sure since I don't own Beersmith) provided a check-box so the user could mark it as unfermentable if they chose. Why it would be a choice seems odd to me. That can be a problem. (It has certainly generated more than a few panicky forum posts about stuck fermentations.) The way all the programs ignored the grain bill's contribution to wort fermentability was the main reason I built my own. It's not just conventional thought. It's been proven in tests and through massive practical experience that each malt/fermentable/non-fermentable has its own relative fermentability character. (And it's not just binary fermentable/unfermentable.)
Sorry for the delayed response. I posted late and went to bed. Let's see what info I can offer... I did this when I pitched a new starter, I was trying the krausening method. I bought a pack of imperial organic flagship (200 billion cell count - advertised) and I made a 1.7 L starter from it. The yeast were insanely active when I pitched them in but still no change in FG from that step. American Ale 1056 was the strain of choice which should net me in the 70%s for attenuation Grain bill: 50% 2 row 10% chocolate malt 5% crystal 80 5% midnight wheat 5% dark munich 2% black patent 1lb dark candi sugar 1lb lactose 1lb dme in boil 5.5 gallons This was done in Beersmith 2 but the check box is there for lactose as not fermentable It tastes pretty good! There are definitely residual sugars present though. I don't mind this but I don't want to bottle if bombs are a potential outcome which is why I am going through every possible scenario to make sure the gravity is as low as I can get it. I'm also worried that my continual adding of sugar, starter, etc is going to tank the flavor. I guess we'll see
See, that's the problem with manufacturer's published attenuation ranges and the way most software uses them. Yeast strain is only one factor. The others were mentioned previously. To assume a beer made with 1056 will finish in the 70s is like assuming someone will bench press 35 reps, without knowing the weight. FWIW, I ran your recipe/process through BrewCipher, and it predicts 65%, which is not too far off from where you are (62%). (And if your mash temp were actually a degree or two higher, the prediction would be even closer.) ETA: It's your beer, and the risk of premature bottling is all yours, but I have a hunch this beer is finished.
@VikeMan I think I tried using brewcipher once before but I couldn't get it working on my mac without office. I can try to check it out on my work computer. With my OG->FG I was calculating 58% AA. I did add the sugar afterwards, which apparently fermented out, but isn't the 58% where I sit in terms of the base beer attenuation?
^^^ This. That said, I'd let it bulk age for another month before packaging, just in case. No harm in that, IMO.
For a RIS with a pound each of lactose and DME to finish at 1.040 is pretty normal. Many types of DME are only about 60-65% fermentable at best, so it’s not just the lactose but also a good part of the DME that won’t ferment. Also I wonder what your mash temperature(s) and time(s) were. If too hot or too short, not going to be as fermentable as it could be. If it’s done, it’s done. Package when ready, as normal.
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