Might it be the heating process?
May I offer as a mere science and engineering student that the complicated organic molecules found in foods undergo change when heated?
uncooked mint sauce vs cooked?

Rub mustard into a joint of meat till it is stuck by the moisture and falls off dry, and cook it slowly, no mustard heat, just very tender with a slight tang on the outside
Horseradish does the same as it has a similar set of oils and enzymes that get broken by heat and time.
(tootired Is searching for a funny sig, nothing good so far, Tue 7 Sep 2010, 22:02, Reply)