Fermentation started before I added yeast

[tgolanos]

Cross-posting from another forum:

I brewed a wheat beer 2 days ago to mark my first full year of brewing and decided to wait overnight before pitching my yeast to let it cool to pitching temps. I washed and sanitized my fermenter, pitched the wort after boil (it was still about 40°C at pitching) and sealed it up overnight.

It was a BIAB brew but I got really poor extraction efficiency so I figured I would run to my LHBS in the morning, grab some wheat LME, boil it, cool it, and add it before pitching my yeast at the 24-hour mark.

As I went to pitch the yeast, the airlock was bubbling away and there was a distinct kräusen already forming. My questions:

1. I followed all of my standard cleaning and sanitation procedures. I did drop a cleaned and sanitized freezer pack into the fermentor to help cool the wort, though. I can only guess there may have been something on the freezer pack? There was zero activity/signs of life when I added the LME around the 18-hour mark. It started after adding the LME.

2. It doesn't smell off or infected, in fact I think it smells fine and is fermenting like a beast- I had to add a blow-off tube last night because the fermentation is so vigourous. I'm going to let it ride because I'm intrigued now. Has anyone experienced this with a Weizen? If so, has it turned out drinkable?

 

[Horseshoot]

I am thinking this is an infection. But, hey.... Beer started out (one assumes) as an accidental infection. At this point, I would be inclined to ride it out, and see what happens. If it is yeast that has infected it, this wild yeast might bring about surprising beer.

Mike

 

[day_trippr]

Definitely an infection, but as noted, sometimes those work out.

With all the stuff dumped in the fermenter, identifying the vector may be unlikely.
While that ice pack would certainly be at the top of my list of suspects, adding unsanitized ingredients (including LME) post-boil is always a risk and should be avoided....

Cheers!

 

[IslandLizard]

Yowsers!

That does sound like it's fermenting away with an aggressively working wild yeast and/or some bugs.

You could reboil it, or heat and keep at 165F for 15 minutes to re-pasteurize, Do it ASAP to prevent off flavors from developing, rechill, and then pitch your yeast. The heating cycle may increase the IBUs a little bit and you'll lose some aroma. You can always add new aroma hops (in a hopstand) or just do a dry hop later if need be.

 

[flars]

Infected freezer pack may be the culprit, but do you grind your grains in the brew room. Bacteria in the grain dust can be an infection source.

 

[tgolanos]

... do you grind your grains in the brew room. Bacteria in the grain dust can be an infection source.

I've never head this before, but I can understand the reasoning. I don't have a specific brew room because my house is so small. I ground the grains in the living/dining room, boiled and cooled in the kitchen, and the fermentor stays in the office.

Would it be better to grind the grains outside? I do have a front patio off the living room so I wouldn't have to lug kilos of grain too far.

Side note: Fermentation is slowing since the blow-off tube not showing too many signs of life. I had a quick peek with a flashlight and I can still see a good kräusen layer. I'll post a pic once it settles.

 

[tgolanos]

Quick update: It's been a week and active fermentation is definitely finished. I had a peek through the airlock and NO PELLICLE! I'm fairly certain I've escaped the infection threat.:rockin:

I took a gravity reading and it's sitting at 1.011. I never had a chance to take an OG reading because of the fast fermentation, but Brewers Friend estimates it was 1.060. I tasted the sample and there are no banana or clove esters that I can taste yet. There is a bit of a sour-fruity hint to it, which isn't really a bad thing. It doesn't taste very wheat beer-y, though. I'm hoping another week or so in the fermentor will fix that up.