Originally Posted by Gear101
What if a home brewer got an infection and put the wart/beer back into a kettle and boiled it again. The brewer would boil it at 220 for 10-15 mins, hoping to kill off all the contaminates and the yeast would properly get killed off too. Then re-set it back into the fermenter and pitch new yeast, then continuing the process from there. Would that produces any off favors and other undesirable taste things or reduce the ABV?
It depends on how far along the beer was. If it had an OG of 1.054 and is now at 1.052 then the alcohol and body wouldn't be affected much. But if its now at 1.030 then you're going to end up with a very different beer than planned if you boil.
The old yeast cells would actually act as nutrients for the new yeast.
As far as off flavors go, that depends on how much if them the infection produced before you boiled it again. Some might be volatile and boil off while someone would likely stay. I vote you try it if your beer isn't too far along and then taste the wort afterwards. If it tastes terrible then you're out of luck. If it tastes ok then go ahead and pitch new yeast.