Unintentional Spontaneous Fermentation

On Sunday I brewed an American Pale Ale, vaguely resembling EdWort's Haus Pale Ale. My intention was to repitch some yeast I'd had sitting around for a few weeks but the starter "beer" smelled sour and tart so I tossed it. Not having a backup dry yeast package I decided to use the cake from another beer that needed to move out of primary anyway.

Well, one thing led to another and I didn't get the yeast out of the carboy until last night, after the wort sat in a clean carboy for 2 days. Instead of pouring the yeast directly into my new beer I decided to pour it into the 2L flask and let it settle overnight. Then I could decant the remainder of the last batch and add mostly yeast to my new beer.

This morning when I got up my beer was fermenting. Man, that made for an angry day, but after a little exercise and a couple beers I'm feeling better about the situation. I have a few ideas about how the little buggers got in and how I can keep them out next time, but what should I do with the current batch? Do I toss it, keep the temp under control and hope for the best, or let it run wild and see what happens?

If it is already wild, then I say you let it go. Put it in a corner, and leave it for a few months.

You don't have anything to lose by letting it ferment and see what happens.

When you bottle it you should harvest the yeast in case you end up liking it. If the beer sucks you can always throw it out.

let it go man, Might be delish.

How hoppy is it? If it's not too hoppy just let it go, you'd just end up with an american wild ale.

Trencher said:

what should I do with the current batch? Do I toss it, keep the temp under control and hope for the best, or let it run wild and see what happens?

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Honestly, it's extremely difficult to make a good sour beer by accident. There is a 99% chance the wort is infected with the wrong bacterial strains (e.g., acetobacter) and wrong ratio of wild-yeast-to-bacteria...The end result being an undrinkable beer.

Chalk it up to a proper sanitation learning experience and move on...

lamarguy said:

Honestly, it's extremely difficult to make a good sour beer by accident. There is a 99% chance the wort is infected with the wrong bacterial strains (e.g., acetobacter) and wrong ratio of wild-yeast-to-bacteria...The end result being an undrinkable beer.

Chalk it up to a proper sanitation learning experience and move on...

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I'm starting to think you're right... Some thin stringy stuff has started floating to the surface, implying something other than a wild yeast is in there and working. Also I realized that, once fermentation is complete, I will not want my siphoning equipment to touch this stuff so I'd have to drink it from the primary.

Trencher said:

I'm starting to think you're right... Some thin stringy stuff has started floating to the surface, implying something other than a wild yeast is in there and working. Also I realized that, once fermentation is complete, I will not want my siphoning equipment to touch this stuff so I'd have to drink it from the primary.

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If you have adequate fermentation vessels to keep brewing, I would let it run. If you need the vessel for future, non-infected beers, then toss it. Are the odds good that it will turn out good? Not really, bu who knows for sure? You could always blend it too. Brew up another similar beer, with a mild yeast like an American ale yeast or something and then blend the two at bottling/kegging. I am sure it would be fine.

I'd let it sit for 6 or more months and see how it tastes. There's a thread elsewhere about culturing wild yeast... you did the same just on a bigger level.

To sample in a few months - take your old siphon hose - replace it with a new one, and use the current one to siphon old school style (filled with water or sanitizer to start siphon).

curtis97322 said:

siphon old school style (filled with water or sanitizer to start siphon).

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Hell, at this point you might as well just suck start the siphon...what's going to happen? You going to infect it more?

cubbies said:

Hell, at this point you might as well just suck start the siphon...what's going to happen? You going to infect it more?

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That, or go buy a $2 racking cane and mark it with a biohazard symbol...

If it doesn't have a krausen, bacteria you be housin.

Bacteria can be good in some cases, but when the source is completely unknown, and yeast is not clearly the dominant species you could wind up with a bacterial infection that will put you in the hospital. Don't ask me for the logic behind that, it's just my common sense gut feeling.

It could turn out great and if I were the OP, I might even give it a try. Please at least have some Listerine on hand for after the spit!

Well it clearly isn't yeast in there, or even yeast-like. I've been wondering what to do with the stuff, might just throw it out after all, but I don't really need the fermenter space yet. Life has really gotten in the way of my brewing over the past few weeks. Maybe I'll even add some yeast now that it's been sitting for a month.

I'd have to throw in a vote for letting it run wild for a while and seeing what happens. Maybe pull out a sample and see how it tastes. If its terrible, do what must be done. If it seems like it might be ok, leave it sit a while and see what happens. No actual advice, just some opinions here.

This beer aint gonna hurt you Trencher. Worst you'd get is a little sick to your stomach but even that is pretty unlikely. Let it do what it wants, you'll be fine. Could be phenomenal, you never know. Before you add any yeast, take a gravity reading, taste, report findings here first. Good luck!

Human pathogens can't survive in beer. Its too acidic, plus as it ages it will sour and become even more acidic, thus make it even more inhospitable to pathogens.

Now, palatable is a different question... but safe is not a concern with beer. In fact, one of the reasons that people historically brewed beer was because they didn't know if their drinking water would be safe when they moved into a new area, so they'd make "small beer" as a way to have clean drinking water that would keep for a weeks or months.

brewmonger said:

Human pathogens can't survive in beer. Its too acidic, plus as it ages it will sour and become even more acidic, thus make it even more inhospitable to pathogens.

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A better statement is "No known human pathogens can survive in beer". I'd like to think it's not possible, but that's pretty naive.

An example highly adaptive pathogen is e coli. There have been recent studies indicating it can adapt readily to acidic environments. It's highly unlikely anyone would put contaminated chicken in fermented wort, but I'm sure stranger things have happened. :cross:

Let it run wild.

I have a 5g carboy that I add my extra wort to every brewday. I generally have a gallon or so that doesn' fit into my primary so I dump it into my experimental sour carboy. When I started this experiment, about 2 years ago now, I set the carboy outside by a group of crab apple trees in bloom. Every time I add new wort it referments and looks different. I just added some Helles, IPA, and Oktoberfest to the mix a couple weeks ago and this time I got a big billowy krausen. Normally, it is just a pelicle or other weird infection skin. I have put about 9 batches worth of random stuff in there and each time I keep the carboy open during the brewday to introduce whatever falls in there over the 5 hours I am outside. When the carboy gets full, I will give it enough time to heal its wounds get over its sickness, and clear. Then I will taste it and see if it needs to be dumped or bottled.

So in comparison to that madness, I would say your project is totally normal

Give it some time and see what you get!

Boerderij_Kabouter said:

I have a 5g carboy that I add my extra wort to every brewday. I generally have a gallon or so that doesn' fit into my primary so I dump it into my experimental sour carboy. When I started this experiment, about 2 years ago now, I set the carboy outside by a group of crab apple trees in bloom. Every time I add new wort it referments and looks different. I just added some Helles, IPA, and Oktoberfest to the mix a couple weeks ago and this time I got a big billowy krausen. Normally, it is just a pelicle or other weird infection skin. I have put about 9 batches worth of random stuff in there and each time I keep the carboy open during the brewday to introduce whatever falls in there over the 5 hours I am outside. When the carboy gets full, I will give it enough time to heal its wounds get over its sickness, and clear. Then I will taste it and see if it needs to be dumped or bottled.

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Madness indeed! Have you ever actually wanted to drink the resulting concoction?

I have promised myself I would not taste it until it is done. I just need to get my butt brewing more and then it will be full. The next two batches should be a smoked porter and an Am. Weiss, that aught to really make things normal

lamarguy said:

A better statement is "No known human pathogens can survive in beer". I'd like to think it's not possible, but that's pretty naive.

An example highly adaptive pathogen is e coli. There have been recent studies indicating it can adapt readily to acidic environments. It's highly unlikely anyone would put contaminated chicken in fermented wort, but I'm sure stranger things have happened. :cross:

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There is a good reason some strains of E. Coli have adapted to acidic environments. E. Coli is actually a very necessary organism for cows and other ruminants to digest the complex cellulose in grasses and legumes. Typically the rumin (first stomach) of a healthy cow has a fairly neutral pH. However, because we have been feeding grain and corn sillage to cows and cattle now for the last half century, it makes their rumin and subsequent stomachs very acidic, so strains of E. Coli have evolved that can survive in this kind of environment.

E. Coli was not even a human pathogen 50 years ago, because typically they cannot surive the very acidic conditions of the human stomach. The new strain that is responsible for all the outbreaks in recent years (O157:H7) is a product of the system of confinement animal feeding or CAFO (concentrated animal feeding operation).

But as you say, this is not something which a beer could catch from the air, lactobacillus are much more likely, and I imagine even if intentionally introduced E. Coli O157:H7 will probably be a very poor competitor with the other yeasts and organisms in the beer.

brewmonger said:

But as you say, this is not something which a beer could catch from the air, lactobacillus are much more likely, and I imagine even if intentionally introduced E. Coli O157:H7 will probably be a very poor competitor with the other yeasts and organisms in the beer.

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Thanks for the information.

I work at a research institute and, after reading about the potential for e coli to survive in beer a couple of months ago, I've considered proposing such an experiment to one of the staff biologists. I'm 99% sure they'll turn me down, but there's still a [minuscule] chance.

Bump for eagerly awaiting the results of this experiment.

lamarguy said:

Thanks for the information.

I work at a research institute and, after reading about the potential for e coli to survive in beer a couple of months ago, I've considered proposing such an experiment to one of the staff biologists. I'm 99% sure they'll turn me down, but there's still a [minuscule] chance.

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I'm thinking the alcohol will take care of them, that's the other reason besides the PH that not much can survive in beer.

amercuric said:

Bump for eagerly awaiting the results of this experiment.

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Yeah, experiment! I didn't completely screw up an eagerly awaited batch of pale ale!

ethanol + low pH seems to be quite effective at controlling/killing e coli
Augmentation of Killing of Escherichia coli O157 by Combinations of Lactate, Ethanol, and Low-pH Conditions

Boerderij_Kabouter said:

Let it run wild.

I have a 5g carboy that I add my extra wort to every brewday. I generally have a gallon or so that doesn' fit into my primary so I dump it into my experimental sour carboy. When I started this experiment, about 2 years ago now, I set the carboy outside by a group of crab apple trees in bloom. Every time I add new wort it referments and looks different. So in comparison to that madness, I would say your project is totally normal

Give it some time and see what you get!

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Interesting, I'm doing the same thing on a smaller scale with my samples, just dump them in the 1 gallon "carboy" after testing. Recently the krausen is a pure white powdery looking layer, looks to be between flour and cottage cheese consistency. The only other difference is I leave it "open" (screened with a small jar over the top) Yeast from the dirt cellar I guess, do you have an airlock on yours? Should be really funky I'll wager, mine's only about 6 months old so far though.:cross: