How long until an infection shows?

[kwingert]

I brewed last Friday and took a contamination sample without yeast in it. On Tuesday, the sample looked clean and there was no pressure in the jar. I used a mason jar and tightened the lid down. I opened the jar to have a smell and it smelled like wort. Today, there is what looks like krauson and the jar has pressure bit up in it.

Could the sample have been infected before I opened it and is it just now showing signs or did I infect it when I opened it?

 

[david_42]

Most likely it was contaminated when you opened it.

 

[Gameface]

Wild yeast are everywhere. If you don't provide a healthy colony of yeast to take over some other yeast will give it a go.

 

[DarthMalt]

It's difficult to have sterile wort at pitching time. In fact, very difficult. The point of sanitizer is to eliminate as much bacteria/wild yeast as possible, but it doesn't kill them all. What's left over is soon pushed out by a larger, healthier yeast population (provided you pitch correctly) that quickly consumes the available food as fermentation starts up.

If you took the sample without pitching any yeast, whatever bacteria/wild yeast that wasn't killed during the sanitizing process is still present in the wort and will slowly begin to reproduce. Without any competition, over time, a larger population will develop and start to show signs of fermentation.

I really wouldn't worry about your beer unless it didn't ferment. If fermentation took place, the unwanted bugs most likely died in the process.


EDIT: I bet 9 times out of 10 your "contamination sample" will live up to it's name and eventually show signs of contamination. Unless you have some way of completely sterilizing all equipment and the wort itself, you'll likely have some sort of organism living in there. After all, it's wort! Bugs love that stuff. That's the whole reason brewers pitch yeast into it!

 

[COLObrewer]

I'd wager that it is infected by some airbourne saccharomyces strain, wild or commercial. Contamination sample is a new one on me, is this taken to give the brewer something to fiddle with until it is infected with something to keep him/her from fiddling with the "main" beer?

 

[trumpetbeard]

What exactly do you mean by 'contamination sample'?

If you mean 'a sample taken to determine whether the rest of the batch is also infected' you probably have nothing to worry about. The yeast in the rest of your beer will create an environment difficult for a lot of nasties to thrive in.

And as to whether there are (visible) signs or not, it entirely depends on the type of infection. Some will grow massive bacterial cultures on top of the wort, others won't give any indication other than through horrendous smell and/or taste. If there was no Kraeusen until after you opened it up the second time, I would suspect that's when it became infected, if in fact it is. Wort without yeast is an excellent environment for all sorts of funky things. I would continue to monitor and check the smell out of curiosity. You may have a totally innocuous spontaneous fermentation. That would be awesome!

But to answer your question, infections are usually (so I've read, never had one) pretty insidious in that they tend to manifest slowly over time. However some can take hold really quickly and show visible signs after not much time. For a similar concept think of how quickly beer can kraeusen after pitching yeast. Same concept (i think).

Hopefully someone with a solid science or infection (beer) background can chime in. I'm definitely no biologist and have only minimal experience 'infecting' sour beers.

 

[Qhrumphf]

I'd wager that it is infected by some airbourne saccharomyces strain, wild or commercial. Contamination sample is a new one on me, is this taken to give the brewer something to fiddle with until it is infected with something to keep him/her from fiddling with the "main" beer?

I've usually seen the technique called a "wort stability test".

 

[kwingert]

Thanks for the replies. I really think it got infected when I opened it. I work in a feedmill and I opened it before I took a shower. It really looks like a yeast fermentation going on in there.

The reason I take a "wort stability test" (I like that better it sounds more sciency) is to check the level of contamination. The idea is if you see no signs of infection in the sample then your pretty sure your wort is "clean" prior to pitching. I also take a forced fermentation sample to learn what my FG is going to be.

 

[day_trippr]

[...]The reason I take a "wort stability test" (I like that better it sounds more sciency) is to check the level of contamination. The idea is if you see no signs of infection in the sample then your pretty sure your wort is "clean" prior to pitching. [...]

Mmmm hmmm.

And yet, you're here wondering what happened...

Cheers!

 

[COLObrewer]

I've usually seen the technique called a "wort stability test".

Hmmm, I'm thinking it's a waste of time and wort.

 

[Qhrumphf]

Hmmm, I'm thinking it's a waste of time and wort.

Depends. For my system I'd agree. I've never done it. But if you're using all sorts of plumbing between kettle and fermenter, its an easy way to check for contamination in that part of your setup. I'd imagine its more useful for the pro brewers, but there are (obviously) homebrewers who do it too.