I like this title. I wanted to call it "How Does Your Draft System Taste?", but all I could picture in my mind is a fat 40-year-old on his knees in the garage, head in the fridge, tongue running over the side of a 5 gallon corny keg. So I went with "Hidden Flavors".
The purpose of this post is not to inform, but simply to suggest an experiment to find out if it's possible to track down flavors in your beers that may not come from fermentation, or contamination, but from your draft system. Now, I realize that how clean your keg is will directly impact the flavor of your beer, but I'm talking about flavors that you might consider as your house flavor. Maybe you have tasted some dry, musty thing in your beer and chalked it up to wild yeast. Maybe some plastic, honey-like flavor and figured it was ingredient based.
I got thinking about this recently because I started to carbonate water in one of my2.5 gallon kegs. Not everyone digs on water with bubbles, especially if it has no booze in it. But I drink so much of it I figure I can just do it myself. So I cleaned a keg, dumped some filtered water in there, and hit it with gas for a couple of weeks. I had to go buy a new faucet assembly for it, because I didn't want my water to taste like beer.
When I took my first sip of my newly carbonated water, I tasted a flavor similar to my beers. I'm not sure why - could be the way I clean my kegs, could be the new faucet assembly. I was tasting a slight musty flavor, with a plastic note from what I imagine is the faucet assembly. Which kind of shocked me, because it was made from draft line that was not supposed to leach any flavors. My drinking water doesn't taste like this at all, so why does my kegged water? I think I clean my equipment well enough. My beer is good. But clearly I was getting a flavor in my beers that I couldn't place normally, until I took out all of the other ingredients except the water and the CO2.
So this is my challenge to you: clean your keg, filter your water, and put it on gas. See what flavors you get from that - do they show up in your beer? They did in mine. What am I going to do about it? I have no idea. But I'd like to hear from anyone who does this. It really sort of opened my eyes to really how much my draft system impacts my beer.