Hi All,
I'm trying to brew a REALLY big Imperial Stout and my fermentation is stuck. I used MoreBeer's Imperial Stout recipe as a base and added more ingredients. See below:
15 lbs 2-row
1 lb Carapils
1 lb Crystal 40
8 oz Roasted Barley
6 oz Black Patent
6 oz Chocolate Malt
2 lbs Oats
1 lb Crystal 120L
1 lb Crystal 60L
1 lb Cane Sugar
10 lbs LME
Yes, I know that's A LOT of ingredients and I ended up with an OG of 1.138 and you could tell it was a bit thick before I began fermentation. I used a S-04 yeast starter (with yeast nutrients) from a previous batch of stout which brought the gravity down to 1.076 after about 4 weeks (took a while). Then I added a brand new pack of US-05 but that barely did anything. It was at 1.074 after 4 more weeks. I know I will need another type of yeast to bring the gravity down but shouldn't the S-04 and US-05 have done more? I calculated the ABV to be at 8.14% right now but I believe it should be up to about 10-11% before it becomes no longer effective. The temperature has been at a pretty consistent 65 degrees.
Any ideas on how to move forward from here and why my fermentation is stuck? What type of yeast do you guys think would be best to get the fermentation back up and going again? My goal is to get it down to at least 1.030. After that, I plan to transfer to secondary and add the following: 6 oz bourbon, vanilla beans, marshmallow extract, and cacao nibs, then ferment for a few more months before canning and storing for at least a year before opening. Please let me know if any of you have tried something like this and if you have any advice or tips. Any advice is much appreciated. Thank you!
I hate to be the bearer of bad news but that’s probably where you’re going to finish.
You can try to warm a little and agitate to get the yeast moving but don’t expect much.
Pitching more yeast into a relatively inhospitable environment (higher alcohol, little oxygen, few remaining easily digestible sugars) won’t do much. Evidenced by your us-05 pitch.
In the future, huge batch of yeast that has high alcohol tolerance and high attenuation, lots of O2 and minimizing less fermentables (caramel/crystal malts and extract).
Maybe add some vanilla, coco, coconut, cinnamon and call it your Christmas pastry stout?
And welcome to HBT!
First, what temp did you mash at?
Second, here's a few ideas;
1. Throw in champagne yeast.
2. Get a starter going and pitch at high krausen.
3.
4.
5. Brew another, but really dry, and blend (not my personal course of action, but it might work for you)
Does champagne yeast ferment maltotriose? If not, it won't help. The original yeast didn't hit its alcohol limit, it hit its stop due to a complex sugar and alcoholic environment.
No it won't, you would need a B01 strain, and even then, I'm not sure how attenuative it would be on it. The suggestion of using champagne yeast or a high krausen yeast starter would be for an inadequate first yeast pitch (underaerated, underpitched, unhealthy, lacking viability, etc.).
A dose of alpha amylase enzyme can help to break down some of the unfermentable sugars. I used it before in an under fermented stout and got another 10 pints of attenuation. Gluco-amylase would possibly break down all the sugars and give you a very dry stout. I don't think I would use Gluco but you could give the A-amylase a shot. If you do a search here on HBT you will find lots of posts about stuck fermentations. You will find some additional information in This Thread
The problem with adding enzymes after pitching yeast is that there is no way to denature the enzymes. They'll continue breaking everything down until there's no flavor or body left.
The a-amylase is limited in its ability. I don't know how to explain the difference well but it has to do with what part of the sugar molecule it works on. A-amylase will leave some unfermentable sugar and not break it all the way down like Glucoamylase.
True. Alpha cuts starch molecules up at random, leaving varying lengths of sugars with varying levels of fermentability. So, I suppose you may be right, the alpha might be the way to go. But I wouldn't count on it leaving a high quality beer in the end. Drinkable yes, but no blue ribbons.
I agree with others that additional enzymes are probably your best chance to take the gravity down much farther. And even then, good luck, because I know based on experience that the alcohol tolerance of S-04 is only 9%. Plus you used 4 pounds of crystal malts and 10 pounds of LME, which are less fermentable. Not sure how far US-05 might take it, hopefully a bit more, but with such a huge OG, most any beer yeast will poop out from the high alcohol. It is extremely unlikely you will end up anywhere close to 1.030 no matter what you do, and anything below 1.050 might be a miracle.
Wort of 1.138 is a really stressful environment for yeast, you need to make sure you're pitching really happy yeast (vitality starters always a good idea), lots of oxygen etc. Also in this case you could have waited to add the LME/sugar, and feed it in as fermentation proceeds, just to reduce the initial osmotic shock.
See this :
/pic/0gxpk4nznot.ppt
But that's for next time, you are where you are. As others have said, it's tough for any new yeast to get a foothold in beer/wort that's 8% alcohol and no simple sugars. You need yeast that's up and running (vitality starter again) and give it simple sugars to get started on, whether that comes from the use of enzymes on the existing complex sugars, or adding some eg glucose.
I'm no expert, but this thread has me wondering if any of y'all might consider diluting with sterile water before pitching more yeast in a situation like this. Or is it just too late to make the environment less inhospitable?
I'd warm it a little and give it more time. I've done RIS where is goes for a month before I add more sugar and keep going.
Granted 1.138 is up there. I just pitched US-05 into a 1.130 and it started chugging away strong within a few hours. Hope it keeps going cause I got 2# maple syrup planned for secondary phase.
Post time 2022-12-10 11:11:36
