Stuck Fermentation..

[SBaker]

I came home from a two week holiday to find my Imperial Stout with a stuck fermentation.
My OG was 1.090 and now after 5 weeks in the primary it reads 1.040!
I used 2 packets of Safale US 05 and stirred with a drill mixer for good aeration. The fermentation took off within 6 hours. I had the fermenter in a fermentation cooler with temps set at 65f to 68F for 18 days.
Fermentation was still active so I did not transfer it to the secondary before I left on holiday. I attributed this to the fact that it is a high gravity beer  - original grain bill = 24.5 pounds.
Upon my return there was no noticeable action, I checked the gravity and with a hygrometer it read 1.040! * checked with my refractometer, after calculations, it was about the same.
Here is what I think happened:
We had set the home ac/heat to 60f, which is lower than the average temperature range for this yeast. The house could of dripped lower than 60f in the room where I do my fermentation.
Lowering the temperature to 60f stopped the fermentation.
Here is what I've done:
I raised the temperature around the fermentation bucket. ( using a spot light, door open on the fermentation cooler ). The bubbling started up again as the temp of the air approached 70f.
It's been 2 full days since it started bubbling again and is still working.
At this point should I worry about any off flavors from not transferring the beer off the fallout and trub? It tastes good, btw.. but I don't want a small stout.

 

[BOB357]

Most home brewers don't even use secondary unless it's a beer they want to bulk age for more than 6 weeks or so. Most of the flavor is developed in the first few days of fermentation, so I really don't see a problem. I'm sure you're going to want to age this for at least a couple of months. Just wait until fermentation finishes up and then transfer to secondary. You've already done what you can, so RDWHAHB!

 

[SBaker]

Thanks Bob,
It never hurts to have a second opinion.

 

[BILLY BREW]

I have been using secondary process for years to clear and let the final wort rest out. It sounds like your yeast nodded off while you were on vacation. If the whole thing was kept sanitary and you had no funk get in, then you will have no issues with the final result.
Now saying that, if you kept the wort on the primary with the yeast and trub for all that time, you may get some off flavors, but that would be due to the fact that it sat for so long. On the other hand, if it is a big beer, you may have a really awesome brew at the end. It just may take a little extra time to mellow out.
Keep us posted.

 

[Kevin58]

US-05 wouldn't be my first choice of yeast for a RIS but it should have worked much better than that. Did you oxygenate when you pitched the yeast? Did you use a yeast nutrient?

Fermentation temperature is important but it doesn't sound as if you have a way to control yours other than relying on room temperature. That being said, the temps you cite shouldn't have hurt anything. You really should however find some method of measuring the temp of the wort inside your fermenter even if it's just one of those temperature tape strips to put on the outside of the bucket. Cooling the fermenter can be as simple as placing it in a water bath and heating can be achieved with an inexpensive Fermwrap heater.

As for using a secondary step. You don't need to. It used to be thought as a necessary step to get the beer off the yeast cake to avoid off flavors but that turned out to be not true. The risk of oxidation during the transfer is far worse than the beer sitting on spent yeast cells Remember: oxygen at the beginning of fermentation = good while oxygen after fermentation = bad.

Big gravity beers take time so leave it for another week or two and then accept what you get at the end.

Next time you may want to try some new things... Start by using yeast nutrient during the boil. Its cheap insurance to help give your yeast a fighting chance.

Second, pitch enough yeast. I prefer a liquid yeast starter for most beers but especially high gravity beers. Pick one that is suited to the style and tolerant of high alcohol. Or better yet, make a normal strength beer first and make your big beer on the same day you package the smaller one... put the big beer right on top of the fresh yeast cake left over from the small one. You will be amazed at the difference.

Next, oxygenate or aerate you wort the best you can before you pitch yeast. Oxygen is a nutrient for yeast. It helps them build strong cell walls and they will need that when the alcohol level rises.

Finally, if you can, control the temperature during fermentation starting with the temperature at which you pitch the yeast.

You will notice all of those steps revolve around yeast health. That is because we as homebrewers make wort. It is the yeas that makes the beer. They are little living creatures and the more we can take care of them and ensure they have everything they need to live their life cycles the better the beer they will make for us.