Off Flavors!!!

Hello all. Got a question about some off flavors.
I recently brewed three batches of beer, one a porter, an IPA and a Smashing pumpkin ale for the wifey. I just started kegging beer after building a new kegerator out of an old freezer. After racking and force carbing these three batches I am getting a banana flavored aroma and flavor coming from the beer. All beers fermented in an ambient temp of ~60 degrees. I was thinking at first that the CO2 that I used to force carb gave it this flavor as none of the beers seemed to have this flavor when I racked it. Any help would be much appreciated. Thanks,
Justin

To me, "banana" says "stressed yeast". That usually means high temperature fermentation or underpitching. If the ambient was 60 degrees, you were probably ok, but it's important to monitor the temperature of the beer, not the ambient temperature. A "stick on" thermometer can easily fix that.

Some yeast strains taste fruity if fermented above 70 degrees or so, so it's possible that your temperatures creeped up above 70, but not likely unless you pitched the yeast before the wort got down to 65 degrees or so after brewing.

Underpitching is more common with liquid yeast, so if you used a liquid strain, that could be the problem if you didn't make a starter. Dry yeast tend to have enough yeast cells in a package, so it's not needed.

Some yeast strains, like hefeweizen yeast, are notorious for being banana-y but if you didn't use a "fruity" yeast strain, then I doubt that would be an issue at all.

Is it common to not have those flavors before carbing? I used US-05 for two of them. Thanks for the comments.
Justin

Rohrbeezy said:

Is it common to not have those flavors before carbing? I used US-05 for two of them. Thanks for the comments.
Justin

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I don't think it's common at all. I don't know why the flavor wouldn't be there before carbing and is there now. Unless it was there earlier, but some malt sweetness covered it up. Hopefully, it'll improve with some time or at least fade.

I've heard that S05 can be "peachy" at very low ale temperatures, and I detected that myself but that was at a fermentation temperature of under 62 degrees. Over 70 would give a "banana"ish flavor. If it's not fermentation temperature, I have no idea what it could be. I'm scratching my head over this one.

I agree it most likely is high fermentation temp. I'll had this problem a couple of times and your best friend is time...A couple more weeks and it will be a lot better. Not sure if it will completely go away, but should get a lot better.

I am having the same issue in about 12 batches. I have never bottle conditioned and have only force carbed. All batches tasted great post boil and post fermentation.

It has been very discouraging. We had several glasses of our last batch before it was carbed and couldnt wait to tap the keg but when we did it had the same off flavor as all of our previous batches.

I keep looking for answers but can't really find any.

Think I am going to try and keg condition our next batch.

All batches that were forced carbed sat in fridge on tank. Should it maybe sit at room temp until fully carbonated?

No carb in the fridge. Co2 absorbs way better cold. Be patient. Carbed beer is not conditioned beer. Beer needs atleast 4 weeks total to taste decent. If you are fermenting for 10 days then force carbing in a couple days...it is going to taste like crap...Also be sure the kegs are clean and the o-rings aren't tainted with whatever was in the keg before you started using it...

I would clean everything and ferment the next batch 3 weeks then keg and force carb at 12psi for 2 weeks and see how it is...i know patience is no fun but it should fix your problem.

good luck!

Will do that. Yeah they usually have been tapped by then so not much time to mature.

I am somewhat recent to kegging but not brewing. I have had a few random batches develop an off flavor from my Final Gravity reading (which I taste and it tastes as I want) to force carbing at 3 x psi for 24 hours then drinking in a few days. The off flavor seems to be similar to DMS.
I flush the kegs with PBW and then use Star Sans to sanitize. There might be a bit of Star Sans left in the beer line but from what I've read it doesn't affect taste.
I have not bottle conditioned to compare but I will try this next batch.

I thought the off flavor was from not letting the beer condition but why would the FG sample taste good?