I always use a Cuisinart with metal blade to knead my dough.  I’ve been reading a lot of articles that state that this is a bad idea as the dough will get too hot and kill the yeast.  So I decided to do a little experimenting to see if this could be true.  Personally, I really never had a problem with that happening in practice, or not that I could tell. From what I researched, it seems that yeast cells begin to die off at 120 degrees and are completely dead at 140 degrees.

 I used my regular 66% hydration with 15 oz of bread flour in the Cuisinart bowl and 2 tsp of yeast.  While it was running I added 10 oz of water through the feed tube.  The water had been heated to 92 degrees as I like to “wake up” the yeast.  After just a few seconds of processing, just enough to mix the water and flour, I shut off the machine and let the dough rest for a 20 minute autolyse.  After the autolyse I checked and the temperature of the dough was 89 degrees. 

 I then sprinkled a rounded tsp of salt all over the dough and turned on the machine for one minute of kneading. After one minute I shut it off and immediately took a reading of the dough in the Cuisinart bowl.  My thermometer was the Thermapen and was very accurate.  The readings in different parts of the dough were from 89 degrees to 100 degrees, an increase of about 10 degrees and certainly nowhere near the temperature needed to start killing yeast cells. 

 So if you use the Cuisinart, have no fear. Unless you start with really hot water, above 110 degrees, there will be no killing of yeast.