Why does rehydrating warm & pitching cool not temp-shock yeast?

Well... I guess my whole question is in the title.

We rehydrate around 100*F, and then pitch shortly after near or below fermentation temps (mid to low 60's, for example). Is this just not a large enough temp difference to harm the yeast? Or does it cause any ill effects?

Thank you!

 

After 30 minutes I would bet that the rehydrated yeast is pretty close to room temperature. I've never worried about it.

 

Yeast are more robust then we give them credit.

 

Over the 15-30 minutes of rehydration period it cools down. Another way to do it is to temper the yeast by spooning in some wort. This is more an issue for lagers where you hopefully chill the wort down to 50F before pitching.

 

I do what Bobby_M mentioned and temper my yeast if I have re hydrated it. From what I have read, a 10° C temp difference can shock the yeast. Not sure what happens to them when they get temp shocked, but it is easy to temper. I use a wine thief and add 4 or so ounces of wort at a time to the yeast slurry, give it a stir, and then give it 5 to 10 minutes to adjust to the new temp. I repeat that until it is within 10° F (or less) of the wort temp. Yes, I do 10° F as opposed to 10° C just because it is a smaller temp difference.

 

AFAIK, there is no such thing as yeast temp shock.

 

This is what is said in the instructions for Nottingham ale yeast:

 

Thanks all for the input!