Over-carbonation -> Off flavour?

[dazsnow]

I tasted the beer when it came out of the fermenter and it was great. I cooled it to 4 degrees then I racked it into the keg and force carbonated - about 1 minute at 300kPa, a good few minutes of vigorous shaking later it dropped to 140kPa so left it for an hour. I then tapped the keg and it was all foam - very overcarbonated... my regulator is a bit dodgy so will go for less CO2 next time.

The thing is, when I tried the beer after the foam settled the flavour was completely different - very astringent, almost plastic-like, flavour :smack:. This is the first time I've use the lines and the CO2 cannister - all brand new.

What could the off-flavour be caused by? Could it be bad gas (I'm in China where nothing is very reliable... I asked for food-grade CO2 but...)? Or bad lines (heat-resistant PVC, only about 30cm long)? Would chlorine in the water be doing something bad with the CO2? Or just the fact that it's over-carbonated so there's excess carbonic acid?

Also, is there any way to resolve the situation? I guess just periodically release the CO2 from the head space to solve the over-carbonation issue, but is that also likely to resolve the flavour issue?

 

[raysmithtx]

I have never had the problem but I did read that you can put water in a keg and carbonate the water. If the taste is there, it's the CO2 causing the problem.

 

[ram5ey]

It could be a number of things like the lines. But co2 does change the flavor when it's over carbed making beer a little drier and more acidic.

 

[Arty76]

I had this problem too, everyone but me tasted it ( I was in denial, I brewed it after all, ha ha) anyway after that I switched to the set and forget method of carbing, about 12-14 psi for a few days, periodically checking it, then reducing the psi to about 6-8 psi for serving , been fine since