Bitter after Kegging

[tx_mke]

I’ve run into an issue with my last 3 batches (all ambers with low IBUs) where after kegging / carbing, the beer turns extremely bitter and doesn’t seem to mellow over time. For my last batch, I racked it to the keg about a week ago. I set the psi at 30 for 24 hours and then back to 10 for the remaining six days. The beer tasted great out of the carboy and was really smooth after 24 hours in the keg. I’ve had a few pints each night to test and thought I had eliminated the problem until two days ago. The flavor is overpowered with bitterness again. I tried the following on my last batch:
• Changed the beer lines
• Replaced gaskets on both the keg and the faucet
• Overnight PBW soak for the keg
• Found a small bit of rust inside the keg. Used BKF and eliminated the rust.
One theory that I do have is could this be oxidization? While working with the regulator last night (thinking possibly that I was overcarbbing even though the gauge showed 10PSI), I released pressure from the keg and noticed that the pressure release valve was pretty loose. Took a couple of turns to tighten it. Although I don’t seem to have a CO2 leak, could oxygen be getting into the keg as I pour beer out, combining with CO2 and oxidizing the beer while it’s still in the process of carbing up? Although the taste I’m getting doesn’t match with what I’ve read that oxidized beer tastes like, could this possibly be the culprit? My next step is to either bottle my next batch to possibly eliminate something I’m doing in the brewing process or to buy a new keg. Any ideas?

 

[Transamguy77]

I would bottle some of the next batch and keg some. How do you get your co2 tank filled? Do you get an exchange or go to the beer distributer and get it filled?

When you change the pressure of the keg are the lines connected? If so are you sure that beer hasn't accidentally been pushed back into the co2 lines? Maybe you have something in them causing the off flavor. Or even the tank if it ran out and beer was pushed into it. Not sure if it's possible but trying to think outside the box.

 

[Callacave]

I want to say it's carbonic acid bite from the 30 psi for 24 hours, but I would think it would fade after those 6 days at 10. I stopped doing that a while back and just do a slow carb at serving pressure, and I find my beers are much better. Maybe some people are more sensitive to tasting carbonic acid?

 

[tx_mke]

Thanks for the responses.

I get my CO2 tanks filled at the liquor / keg store. I'll check the CO2 lines today and might replace them as well. I do have two kegs currently connected to the same bottle, one is a commercial that tastes fine and the other is the bitter home-brew. I'll change my process on the next batch to the set and forget method and see if that helps.