Needing advice on some ..*gulp*.. stuck fermentations

[thecloakedgoat]

I may be being impatient but I am currently having a hell of a time getting two brews to dry out (an oatmeal stout and a strong scotch ale). The stout was brewed 2/12 and the scotch ale was brewed 2/20. Both have been fermenting in my house (typically 66-70F). I do not have an aerator so I used the good ol' "swish the chilled wort around in the carboy" technique. Both are bubbling very slightly, maybe every 2-3 minutes or so. I'm a good cook so I know I can follow a recipe plus I am a winemaker by day and think(thought?) I know how to handle a fermentation (I literally fermented nearly 10 million gallons bone dry this past year). I don't know what to call this other than a stuck fermentation. Coming from a winemaking background I fear that my initial response would be a bad one. Should I re-pitch starters since there is still a small amount of activity? Any advice would be extremely appreciated! Thanks everyone!

Oatmeal Stout
OG= 1.073
Currently= 1.031
Yeast= Wyeast 1028 London Ale <--- 1 pack

Strong Scoth Ale
OG= 1.083
Currently= 1.039
Yeast= Edinburgh Scottish Ale WLP028 <--- 1 vial

I made two day starters for each at ~500ml

[BrewerJ]

What was your mash temp? You can always try to make a fresh starter and pitch it into the beer. My guess is that oatmeal stout has a fair amount of unfermentables. How much oatmeal did you use? Sometimes oatmeal doesnt convert all the way in short mash schedules. I would swirl the carboy of the scotch ale and get the yeast back into suspension and give that beer more time.

[Stinkfist]

Sounds to me like you underpitched those are pretty big beers and a 500ml starter is not going to be enough yeast.....If you do repitch make it is a active starting meaning the yeast is actively fermenting when you add it to your beer, do not chill it down and decant...it needs to be very active to survive the harsh conditions you are putting them in..

[maxwell]

You definitely underpitched both batches. The propagation section in the yeast book is informative - definitely worth a read. Bottom line is that even if you had 100 billion cells to start with, you may have only added ~12 billion with your 500 mL starter in the absence of agitation or oxygenation. A beer the size of your stout would need a 3.73 liter starter with no agitation or 1.4 liters on the stirplate. I was having the same problems when I got back into brewing a couple of years ago and making stirred starters has really helped the attenuation of my beers.

Max

[thecloakedgoat]

Thanks for the feedback. My copy of Yeast just arrived in the mail yesterday so I'm sure I have lots to learn. I'll build some big starters this weekend.

As for the mash schedules:

Oatmeal Stout= 20 minutes @ 122, 50 minutes @ 152, mashed out at 165

Scotch Ale= 90 minutes @ 149, 45 minutes @ 157, mashed out at 165



Thanks again!

[BrewerJ]

Well your mash temps look great. Double check your thermometer to make sure it's on. If it's off by four degrees then that could have a pretty big effect on your fg

[Crackin]

I woudn't pitch a huge (3 liter) starter at this point. Remember, you are no longer at 1.073, and a huge starter will affect the flavor of your beer. I would pitch maybe a liter, really just to get the yeast active before pitching. One vial / pack should be able to ferment the remainder of the fermentables, I think.

[EagleDude]

You always have Brett as an option ... Just curious what yeast were you using? I have had some odd fermentation issues when using different strains/brands on the same wort. I do have a pretty damn good Dark Strong with B. lambicus that is coming along nicely as a result.