I am baffled

[BrownsBrewing]

I cant seem to figure this out. I brewed a 10 gallon AG batch with a SG of 1.050. Built up a huge yeast starter fresh from the Wyeast pouch and pitched at bout 72 f. Conical was sterilized properly as well as my aeration stone. O2 went through a filter as well. Had great fermentation for a couple of days then got stuck at 1.025. I built up another starter to try to kick start the fermentation again, but when I opened the fermenter to pitch my wort smelled like puke and had white and green powder floating. Lately Ive had the problem of stuck fermentation quite a bit. I dont know how Im screwing up.

 

[Daddymem]

All grain or extract?
Fermentation temperature?
Sanitation procedures both fermentation vessel and starter?
Have all the stuck fermentations had signs of infection?

 

[BrownsBrewing]

All grain as stated
Fermentation temps varied according to the time of day, but nothing drastic
I am a stickler for sanitation
Other stuck ferments have had a nasty sour aftertaste

 

[Daddymem]

Old or infected soft components like hoses, siphons?

Not that it would cause sour aftertaste but is your thermometer calibrated, too hot in your mash and you could get lesser fermentable sugars, that got me in a tripel once, 8F hotter than the thermometer read and 60% attenutation with the High Gravity. Can you say sweet beer?

 

[Daddymem]

P.S. I'd by no means consider myself an expert (probably less experience than you actually) but I figured I'd at least take a shot since there weren't replies yet. New eyes can sometimes catch things.

 

[Montanaandy]

Which Wyeast did you use?

How large/many liters was the starter (you state that it was huge)? Was the starter on a stirplate and if so for how long?

How are you transferring the wort into the conical? Pump with tubing from the BK?

Montanaandy

 

[BrownsBrewing]

1084
800 ml
Kettle to an enclosed bucket to conical. Yes I sterilized the bucket and spigot

 

[hook_dupin]

I think you may be underpitching your yeast a bit. With starters, as with other things, its not how big it is, but how you use it. With yeast, its the cell count and not necessarily the starer size that's important. For a 10 gallon batch, you need at least a 1500 ml starter to get the attenuation right, and that's provided that you used a stir plate to stir the starter for a couple of days. Bacteria can grow six times faster than yeast, so an underpitched wort can quickly turn into disgusting slosh. Here's a pretty good article on good yeast culturing practices: http://archive.maltosefalcons.com/tech/MB_Raines_Guide_to_Yeast_Culturing.php

 

[BrownsBrewing]

How much of that 1500 ml should be slurry?

 

[Montanaandy]

Yeah, I would at least double your starter. I normally pitch a 1800-1900ml starter with Wyeast and have have good results. As to how much should be slurry, I just pitch the entire starter after it has sat on the stir plate for 48 hours. Monanaandy

 

[Montanaandy]

I meant to add that I pitch a 1800-1900 ml starter for a 5 gal batch so you would need a larger starter for a 10 gal batch. Montanaandy

 

[mojotele]

Mr. Malty says you'd need a 4160 mL starter for 10 gallons of wort at 1.050 OG using only one pack of yeast, shaking it from time to time, and assuming the production date is today. Clearly the production date is earlier than today, so you'd actually need a larger starter.

I'm not sure how much mL of yeast slurry that works out to. Sorry

 

[Picobrew]

This bucket has me nervous! Have you taken apart the spigot? There are regions that are quite hard to sanitize in there. Also, you said sanitize once and sterilize the other time. What technique did you use with the bucket? Star-San, Iodophor, Boiling Water, Bleach?

I have also heard numerous times to never bother with a starter under 800ml. I end up doing a 1600ml starter even on low gravity 5G batches, and this is with a stir plate.

Like others have said, underpitching will give any minor contamination more of a chance to take hold.

 

[jimwormold]

Has somebody been sick into it by accident?

 

[jimwormold]

Has somebody been sick into it by accident?!

 

[rcrabb22]

How much of that 1500 ml should be slurry?

Many people will pitch the entire starter volume. I usually make 2L starters which is equivalent to .53 gal or 10% of my fermenter volume. Even if I could be convinced it wouldn't affect the flavor of the end product it adds enough liquid volume to impact headspace for krasuen.

So, I will pour off as much spent starter as I can before pitching. I plan ahead and refrigerate my starters for 2 days after 24 - 36 hours on the stir plate to encourage yeast flocculation to the bottom of the flask. On brew day I pour off the spent starter and bring it up to fermentation temperature for pitching.