Originally Posted by Tech211
I never warm my chilled starters. I figure that the slurry will reach the proper temp quickly when it hits the wort. I'm not even certain that the yeast would become active if you simply warmed it with nothing for them to eat.
The yeast will be active when you put it in wort, but putting cold yeast slurry in warm wort is pretty shocking for the yeast. If you don't want to stress the yeast, you can pitch slightly cooler yeast into the wort. When I make a lager, for example, I'll pitch a 48 degree starter into 50 degree wort and the yeast like that!
But to take it out of the fridge and throw it into 70 degree wort is not a great idea. That would be stressful to the yeast.