If pellicle forms on beer that was left out, does it mean keg is also infected?

[BrewVerymore]

Hello everyone

So about a week ago I posted about a wheat beer that I brewed with kiwis having a mild tartness to it despite the fact that when I tasted the kiwis themselves, they weren't tart at all. I wasn't sure whether the tartness was from an infection or not.

Anyway I had a glass of the beer that I poured from the keg and just left out in a room. 2-3 days later I noticed a well developed pellicle had formed on top. It looked exactly like THIS. Is this any indication that my vessel was infected and my kegs as well?

I know this is a stupid "test". It actually wasn't a test really. The beer was just a glass I used to pour foam into and I left it out and forgot about it. I'm dying to know whether my beer is infected, but I don't have the palette experience to taste whether or not it is. The beer tastes delicious and doesn't smell bad. I'm pretty stumped. Ever since I read a post that said, "Tartness doesn't come from wheat. It probably means your beer is infected" and I've been paranoid since.

Any help would be greatly appreciated.

 

[madscientist451]

Fruit contains several flavor components including sweetness and acidity.
When you use fruit in brewing, the sugar is consumed by the yeast and you are left with a tart flavor and some aroma that gives a hint of the original fruit. Sure, your beer could be infected. A better experiment would be to sanitize a 1/2 gallon jug, purge with Co2, and fill about 3/4 with your kiwi wheat beer. Put an airlock on it and see what happens.
If your worried about the infection in the keg, I'd go ahead and drink the rest of it while it still tastes good.

 

[AMessenger]

I think the most likely explanation for the pellicle is from something in the keg rather than the glass or just the air.

I would think you'll see little flavor influence in the keg if you keep it at serving temps though.

 

[seatazzz]

Not that I should admit it, but I leave beer glasses out overnight (sometimes longer if I forget where I left it) with beer still in them, and I get that pellicle-looking thing quite often in them. I'm willing to bet it's something nasty from the air, not in your keg. I've only had 2 infections in 30+ batches and both were due to poorly cleaned equipment (problem since rectified). Even the cleanest house/garage/brewery/cave will have some fruit flies hanging around and they can easily get something like that started in stagnant, warm beer.

 

[carloslavin]

I'm going with "the pellicle means nothing" people. 2 days of open air exposure can get you a lot of nasties.

 

[BrewVerymore]

Thank you guys! I had some people over tasting the beer and they said it didn't taste infected at all and actually quite enjoyed it! Thank you!