Puzzling development (deals with oxidation/metallic taste)

[boomtown25]

I have a had a peach blonde ale on tap in my kegerator for a couple weeks now. Started out good, and with a week or two on carbonation, I felt it improved. However, lately I have picked up some metallic taste. I know this is a common characteristic of oxidation but how can that be? Am I being overly sensitive and looking for this (I have had serious trouble with oxidation during fermentation in the past) but this time it was clean and was good. Still 100% drinkable, but can beer which has been in the keg for over 2-3 weeks on the keg become oxidized?? (no known exposure so I can't figure it out....)

 

[schematix]

Can you describe your racking and carbonation techniques?

I spent years drinking beer with that metallic taste developing after a few weeks. Finally figured it out but it’s a lot of work.

 

[boomtown25]

Single fermentation vessel so no exposure to oxygen during transfer to secondary.
Proper sanitation of all racking equipment (star san) and cleaning of the keg.
fillled keg with CO2. Racked with minimal splashing with autosiphon from primary fermentor keeping maximum trub out (suspended siphon above, leaving decent amount of "spare" beer in fermentor after filling 5 gallon keg".
cold crashed and gelatinized beer. Purging headspace with co2 each every step of the way.
48 hours on 30 psi, purged headspace, dropped to 10 psi for week. On tap. only started developing metallic taste lately, maybe 2.5 weeks on tap.

 

[boomtown25]

May be non-issue but metallic taste is most noticeable in head of beer and not liquid

 

[schematix]

forced carbonation is your main point of failure. 99.9% pure CO2 still has a lot of O2 in it and your forcing it in.

look up spunding, or even naturally carbonating in the keg.

 

[boomtown25]

So........if I wanted to carb naturally, and as quickly as possible, could I rack into a keg for secondary before fermentation is done, set a spunding valve on the keg at 10 PSI and let it sit 1-2 weeks and then hook up to keg for dispensing or am I missing something? Or would I have to resort to the keg as tertiary to get it as clean as possible, add priming sugar to keg and then use the spunding valve?

 

[schematix]

I normally try to rack just barely above FG... usually about 2 points will nail it. Racking point too early is better than racking a point too late though. You'll probably find you reach desired carbonation (i.e. pressure) level within 1-2 days and then you can cold crash to stop the ales. Lagers you need to vent.

The other alternative, which isn't as good, but is better than just force carbing, is to let the beer get to FG, and within a day add priming sugar right to the primary, once it starts to bubble again, rack it. This will give you less sediment, but you will get more O2 pickup.

You should see dramatically improved shelf life from either technique.

 

[Beer-lord]

I went thru something similar a while back and tried everything. In the end it was my RO water filter. I had gotten a second unit and for some reason the manufacturer told me that some of their filters cause this and sent me 2 replacement filters. I made the change and was back in business.