The Danger's of pitching the heat

[MmmBeer]

What is the danger of pitching the yeast when the wort is too hot? Is there an acceptable range? I have pitched several times before at temps above 85 degrees and have not noticed a negative effect, or am I just not noticing it because I do it almost every time?

[Beerconnoisseur]

The big one is that high temperature can kill off the yeast, which may require repitching, and the associated headaches that can result.

You can also "shock" the yeast if the temperature swings are big enough, which will also produce off-flavors.

Finally, at higher temperatures, yeast can mutate, even producing more fusel alcohols/oils which are thought to contribute to severe hangovers.

[LorenzoJ]

Also keep in mind that the most vigorous part of the fermentation cycle can raise the temp another few degrees......... and some quite unpleasant fusil alcohols can most certainly result