Wort fermenting without yeast?

Please help me solve this mystery.

So I brewed an IPA on Saturday evening and forgot to make a yeast starter for the yeast I am reusing. I realized this half way through the brewing process, so I went ahead and made a starter during the mash rest. After finishing the hop boil, I cooled the wort down to proper yeast temps, racked it into a sanitized fermenter and sealed it off with an airlock. My plan was to let it sit overnight and pitch the yeast the next day.

Well that was Saturday....I wasn't satisfied with the starter on Sunday (took forever to get it going), and decided to pitch the yeast on Monday. Well I come home from work on Monday, and Lord and behold, the fermenting vessel was bubbling with wort in the air lock. WTH? Why is it bubbling, I did not pitch the yeast? Is it residual yeast from past brews? Wild yeast? Bacteria? I pulled the airlock off, and it appeared that there was yeast on the bung. I went ahead and pitched the yeast I was reusing anyways, but I have a bad feeling about the final product of this beer. Any ideas?

 

Its probably some sort of wild yeast that got in during transfer or was in the fermenter already. How did you clean the fermenter after the last batch?

 

Yep. Probably wild yeast, or anything really. Most of the time or equipment is sanitary, not 100% sterile, and we generally transfer in open air.

You should always pitch the yeast as soon as possible after the wort has cooled, so that the billions of cells you pitch will out compete the small handful that will invariably get in your wort. The, say, five wild yeast cells that floated in, had 48 hours in ideal conditions to multiply to their hearts content, with a huge amount of food and o2.

 

Its probably some sort of wild yeast that got in during transfer or was in the fermenter already. How did you clean the fermenter after the last batch?


I always clean my fermenters by swirling a hand towel around with hot water until the fermentor appears clean, and give it a good rinse. I always sanitize the fermentor with 1 step on brew day, 20 minutes or so before I rack. Thanks for the response, I am baffled.

 

If it is wild yeast, I wonder if this batch will still be drinkable or be spoiled....ugh only time will tell.

 

Do you use a cleaner...like PBW or OxiClean Free? Or do you just swirl the towel in with warm water?

 

I just swirl hot water with a wet towel. Do you use additional sanitation? Sounds like something I should look into.

 

I am paranoid about sanitizing/cleaning but I know starsan doesn't clean so you can't use that as your only cleaning source.

I fill my fermenter with a scoop of OxiClean Free and let it soak in hot water for at least 30 minutes. Usually I fill it up before I start brewing and let the Oxi sit in there until I go to cool the wort which is when I rinse all the Oxi water out and fill with sanitizer until I am ready to transfer.

OxiClean Free is available at Target I know and it like $8. You don't have to use a bunch so it will last you many batches.

I clean everything that comes in contact with the wort in a oxiclean solution before I sanitize this way I am assured my process will be clean.

 

Thanks for the tip!

 

Of recommend you clean your fermentor (carboy/bucket) w
/ a soak in B-Brite or other cleanser & hot water for about an hour followed by a good rinse. Then sanitize w / StarSan before use.
I also put a solid bung in my carboys after drying while they're stored.


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I've ran into this prob before. Next time just boil the wort for fifteen min to sanitize place a sanitized cover on the kettle last min of boil. Leave until the yeast is ready.

There is always wild yeast. You're covered in it. I can tell you, however that if you had that much activity after only two days you really need to improve sanitation. I would not expect any serious Krausen and at least five days before you even had much activity. I have inadvertently made wild yeast beer with starter wort I was trying to save in a five gallon bucket. There was no activity through the airlock until ten days after it was sealed.

 

This is a cool story. +1 for oxygen type cleaner. I use b-brite, much cheaper than PBW. Also consider yeast could have come from the airlock or bung. Beer just shoots up against them during fermentation. If its the same strain as last time I would just.go ahead and pitch personally.