Originally Posted by abenz419
first off i'd like to point out that as one guy said before.... you might have bacteria cause you pitched so high....... that is completely false... if anything pitching at such a high temp would decrease the likelyhood of bacteria seeing as how high temps kill bacteria.... and secondly a little known fact is that beer yeast ferments best at 90* F and dies at over 100*F, the reason we don't ferment beer at 90*F is because at that high of temperature beer yeast produces so much acetaldehyde that it makes the beer undrinkable... to get the desired aromas and flavors from your yeast it needs to at around 68*F (at least for ales)
I'm not wanting to argue with anyone- so take this FWIW. Bacteria grows best between 90-140 degrees. That's why when you go to a picnic you only leave food out for 2 hours, then cool it, or heat it up. That's the main danger zone.
That's why we chill our wort to 60 degrees as soon as possible, and pitching the yeast is desirable under 70 degrees.
You're definitely right about the off-flavors at high temperatures- but that is because of stressed (dying) yeast.