Off flavors only while cold?

[veritas524]

I'm approaching day 14 on my hef that I made and took a SG reading to check against in a couple of days. After taking my sample of course I had to taste it! To my surprise this has been the best tasting sample I've ever pulled out of a carboy. I was so excited I tossed the rest of the test jar into a glass and decided to stick it in the freezer to taste it cold. After about 20 minutes I pulled it out and took a big swig. It tasted like a got smacked in the mouth with a bag of green apples. I understand that this is caused by acetaldehyde (SP?) because the beer needs to condition and what not, but why wasn't this flavor prominent when it was warm? I couldn't taste it at all, and then when it was chilled it was very intense.

 

[pericles]

Aromatics volitalize at warmer temperatures. That's why English ales with complex malt profiles are served warm, and lagers, which are subtler and prone to sulfur flavors, are served cold.

My bet is that the green-apple flavor was present when the beer was warm, but it was masked by the stronger aromatics. When the beer was cold, the aromatics were gone, and the acetaldehyde was all that was left.