Kegged beer tastes great at first, but then more bitter half way through the keg?

[Richard-SSV]

So I made a 5 gallon batch of of an Irish Red and split it up into two 2/12 gallon kegs. The first keg tasted great until about 3/4 of the way through the keg. At that point it developed a bitter flavor that wasn't there before. The head retention had also dissipated, though the beer didn't seem under carbonated (carbonation set at 12psi).

At this point I switched over to the other 2 1/2 gallon keg from the same batch, which had been at the same carbonation setting as the first. The newly tapped keg tasted great and had great head retention. Now about a week later (and 10 pints or so), the beer has the same bitter taste with no head retention, just as the first keg had.

Any ideas what could be causing this?

 

[Bensiff]

Beer clearing out so you have pulled off some of the material that would aid in head retention while getting a cleaner profile so the off flavors of the trub material are not getting in the way which allows for the hops to be more pronounced and crisp...would be my guess based off what information you provided. Does it have off flavors?

 

[Richard-SSV]

Yeah, it's not a desirable bitter taste. It's more of an "off" flavor.

 

[thadius856]

Never had a keg get "worse" as it got lower. Only better. That's probably because I don't have patience to age them out enough before tapping.

Perhaps you just like the taste of the yeast? As you continue to it off going down the keg, it'll get thinner and thinner.

Edit: Did you burp the headspace 5-6 times to rid all oxygen from the system? Simply pressurizing them up isn't enough. Perhaps you left some amount of oxygen in there and you're just slowly oxidizing the batch over time.

 

[Bensiff]

can you be more specific?

 

[Richard-SSV]

Yes, I purged the head space in the keg with co2.

I would say that it tastes like a flat beer, yet I can still feel the carbonation on my tongue when drinking it. I went ahead and bumped up the psi on the manifold to about 15 to see if that will make any difference.

It's just off to me that the keg was perfectly carbonated before?

 

[tagz]

My hoppy beers tend to get more harsh with time. Wondering if I have bacteria or something in the keg/diptube that could cause this. Did you ever figure this out?

 

[thadius856]

Perhaps you're getting yeast settle out over time as your drink the keg, and towards the bottom you start drawing the yeast up again?

Is it a yeasty taste?

As for hoppy beers... this seems normal. Hop flavors diminish as hoppy beers age, leaving a more bitter overall taste from isomerized alpha acids that remain.

 

[tagz]

For me it happens within days of being kegged. The aroma and flavor hops turn to crap and the bitterness gets unpleasant. This last had a nice citra/ahtanum flavor after dry hop. Within days the aroma has been reduced to almost nothing and the bitterness is somewhat more harsh. It tastes like an ipa that's been on the shelf past it's date. I'm almost afraid to use hops at all these days because my low hop beers are great. But my hoppy beers all suffer the same fate.

 

[thadius856]

For me it happens within days of being kegged. The aroma and flavor hops turn to crap and the bitterness gets unpleasant. This last had a nice citra/ahtanum flavor after dry hop. Within days the aroma has been reduced to almost nothing and the bitterness is somewhat more harsh. It tastes like an ipa that's been on the shelf past it's date. I'm almost afraid to use hops at all these days because my low hop beers are great. But my hoppy beers all suffer the same fate.

I haven't noticed this. I've had a IIPA on tap for... BeerSmith says 27 now. Still tastes (almost exactly) as good as when I kegged it up. The dry hop bag is still in the keg, to boot. It's probably not touching liquid anymore, but still.

Some of the Centennial floralness has, unfortunately, gone. But, I attribute that to purging the headspace a couple times because of poor CO2 management on my part. Not the beer's fault.

I'm force carbing another 5 gallon keg of it from the same brew day, so once the first keg floats, I'll let you know if I can tell any difference between the two.

 

[smooth]

6 months ago I had something like this happen to my setup.

Baffled me.

In my case I think it was my CO2 system contaminating my kegs (3 keg cooler).
I pulled all gas lines, fitting, couplers, up to the regulator and cleaned the heck out of them, and then thoroughly sanitized them.
Re-assembled and I have not had any trouble since.
YMMV

 

[blueseamonkey]

The off-tastes you're describing sound to me similar to those from a poorly-kept cask ale. They tend to taste nasty (horribly bitter or sour,) are flat, have little or no head and if ordered in a decent British pub can be sent back for a new pint.

Although I have little experience with kegs I'd check to see whether you are getting any leaks (on the keg itself or in your CO2 system) that could lead to your keg behaving more like a cask - i.e. letting in air as you take the beer out.

 

[brewingmeister]

Beer clearing out so you have pulled off some of the material that would aid in head retention while getting a cleaner profile so the off flavors of the trub material are not getting in the way which allows for the hops to be more pronounced and crisp...would be my guess based off what information you provided. Does it have off flavors?

This^^ would have been my initial thought.

Do you prefer wheat beers? It seems you miss that characteristic.

What method of carbonation are you using?