[john.flanagin]

Hi,

I was wondering if anyone could help me figure out why one of my beers went south. The recipe is as follows:


2.5 Gal Batch

7.55 lbs 2 Row
.64 lbs C40
.31 lbs Cara-Pils
.2 lbs Wheat, Flaked
.5 oz Columbus at 60 min
.5 oz Columbus at 15 min
1 oz of Columbus at 5 min
1 Packet Nottingham Yeast

I let ferment for 2 weeks then racked on top of 2.5 lbs of mango for 2 weeks. After that I racked to keg and let carb 1 week.

So the samples off the keg were great! Then I bottled it off the keg with the beer gun for friends. Everyone enjoyed it. Then after about two weeks in the bottle it turned. It was really sweet and tasted like green apples. Can anyone help?

[bbesser]

I cant give you a definitive answer, but the description of green apple always points me back to Acetaldehyde.  Acetaldehyde is caused by under pitching, under oxygenating, or removing the beer from the yeast cake too early.

Seems strange that the flavor would not develop until a couple weeks in the bottle.  I guess it may have already been present, but was not noticeable until the Mango had mellowed some.

[Jimmy K]

Acetaldehyde can also be formed after packaging by the oxidation of alcohol. With a beer gun its less likely, but not impossible, that you introduced oxygen during bottling.
 
Acetaldehyde can also be caused by bacterial contamination - It's a step on the formation of acetic acid from alcohol. Although acetobacter also requires oxygen.
 
It could also be ethyl acetate, which is similarly fruity and leaves a sweet impression - especially the aroma. Ethyl acetate is also caused by bacterial contamination.
 
Is it present in the beer that's still in the keg?

[john.flanagin]

When I bottled off the keg I bottled all of it.

[cascadesrunner]

That is a monster of a beer.

[john.flanagin]

Yes. It came in at around 9%. My thoughts were that I didn't have enough hop additions at the beginning of the boil to combat the robust malty profile of this beer.

[Jimmy K]

Perhaps, but sweetness due to lack of hops should have been noticed when you bottled and should not have changed in the bottle. It also would have been a malty sweetness, not a fruity sweetness. It's too bad we can't taste it ourselves. And I was hoping you had some left in the keg to compare.

[john.flanagin]

I plan to make it again. However I think I might leave the Mangos out this time.

[sprider1]

Hard to say  without tasting the beer. That being said I vote  contamination  from the fruit.I  would send a few bottles in to  next contest and  let a  developed palate  taste  it  ,and see on  the score sheet  what  the   problem  was.

[curtism1234]

I put cherries on my beer one time...never again.

How many bottles did you taste? If only 1 or 2, perhaps they could be dirty bottles?