New onset of mettalic taste?

I'm down to the last 12-pack of my very first homebrew attempt - an Amber Ale extract-based batch with some speciality grains steeped up front. I brewed & bottled towards the end of November, and I was very happy with how it tasted!

But over the last week, every bottle I've tasted has had a coppery, metallic taste to it. It's not overwhelming, but definitely noticeable and definitely was NOT there before.

Could it be oxidation from poor bottling technique? From what I read that should taste like "wet cardboard" but that's not really what I am tasting now...

I don't think these last bottles happened to be the first or last ones to be bottled. The beer _did_ have a fair bit of chill haze that I assume was due to my poor cold-crashing (don't have a cooler, just an ice bath and wasn't as agressive with the ice as I should have been), but from what I've heard that's more of a cosmetic problem.

It certainly seems to me that this taste only developed after 2-3 months in the bottle.

Does anyone have any ideas on what this taste might be?

TIA

Metallic off-flavors are usually from your water or your equipment. That doesn't really make sense here since it took awhile for the flavor to develop. If it was the water or equipment, you would have picked it up earlier.

My best guess, and it is a guess, is that you have some low-level infection that has taken some time to produce off flavors. If that is the case, just make sure your cleaning and sanitizing procedures are solid. Otherwise, these folks have some ideas:

https://www.homebrewtalk.com/f13/metallic-taste-63393/

Sorry I can't be more helpful.

Sometimes, I get a metallic like taste from the foam in a beer, espcially when dark roasted, malts are used. I think it's just a combination of the somewhat acrid flavor that dark malts can have with a bit of carbonic bite from the foam. This typically disipates quickly.

It's possible this is a mild infection of sorts that just began to manifest. Would you say the flavor is also somewhat sour? Perhaps its the quality of your bottle caps. Maybe its some type of yeast derived flavor, although odd that is only appearing now.

Oxidation takes many forms. The standard cardboard description is likely based off of the work done by BMC on their light lagers. Oxidation can cause dullness to a beer, or give the beer sherry, caramelly, old, dusty, vegetable, or paper like flavors.

Did you boil your caps? What kind are you using? Is there rust around the rim of the cap when you remove it? Sometimes a simple wipe of the bottle lip before pouring will fix that.

In a beer with darker grains, oxidation in early stages can indeed present as a metallic flavor, especially on the sides of the tongue. If that's what you taste now, and it wasn't there earlier, it points to an aging beer suffering from early oxidation symptoms.

Thanks to all for the replies -

BeerGryllis - I did not boil my caps, but I did soak them in StarSan prior to bottling...

I had some splashing problems when I was racking from the fermenter into my bottling bucket, so Yooper's confirmation makes sense... and of course, with any newbie brewer, a low-level contamination is a problem, although I have a pretty good background in biology and I thought I did a better job with the sanitation than that

Thanks again