Post primary contamination?

[Chaosbourne]

So I've had two or three beers display the same problem and I'm trying to figure out if I have a contamination problem after primary (or even secondary) fermentation. I always thought it was harder to contaminate a beer after primary due to the alcohol, but I seemed to have accomplished it.

Long story short: two of the beers I have made have been extremely light in color, using only wheat and pilsner malts. After primary I've given it a taste and it seems great! Young, but still very good. It is light in color as well.

But after two weeks in the secondary or even after kegging it, the beer becomes somewhat red in color and has a very sweet/off flavor to it. Its not sour by any means, but it doesn't taste like beer. I did dry hop one of the batches that turned out this way, but not both. The only source of contamination I can think of would be the drop tube/out spout/whatever you call it in the corny. I do typically do my secondary in a corny, though I'm beginning to think that I shouldn't.

Are there strains of bacteria that will actually DARKEN the beer? Has anyone else had this problem? I'd like to stop ruining 5 gallons of beer at a time!

 

[Yooper]

A darker color with a hint of sweet aftertaste points to oxidation.

Oxidized beer will first taste ok, then get a "sherry" or "brandy"like aftertaste and darken in color. It will get worse with time, and then begin to taste a bit stale or musty, and in the very worst cases it then can tastes like wet cardboard.

I'd suggest keeping the beer in the primary for 2 weeks or so, then bottling and skipping a clearing vessel to see if that is the cause of this off-flavor. It's possible that there was a large headspace in the secondary, or that the racking allowed some splashing or otherwise oxygen pick up occurred.

 

[Chaosbourne]

Oh ok.

So if I'm already using the corny for secondary, if I lightly carbonate it, or simply purge the oxygen, do you think that will take care of the problem?

I'm sure I splashed it around a little bit.

 

[Yooper]

Oh ok.

So if I'm already using the corny for secondary, if I lightly carbonate it, or simply purge the oxygen, do you think that will take care of the problem?

I'm sure I splashed it around a little bit.

Yes, if you purge the keg with co2 before racking the beer (gently without splashing), then purge the keg once you close it up, that should help with any oxidation issues.