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-   -   What temperature kills yeast? (http://www.homebrewtalk.com/f13/what-temperature-kills-yeast-67272/)

daholl01 05-27-2008 11:17 PM

What temperature kills yeast?
 
I am just curious, I pitched my yeast into my starter a little early because I was in a hurry to leave and I would estimate the wort was about 90-95 deg. F. and the yeast was about room temp. I initially thought that was fine but there is no sign of airlock activity although it is early (only been about 6 hours). I am just curious, about what temperature wort would kill the yeast all together?

Soulive 05-27-2008 11:19 PM

I'm not sure what temp officially kills the yeast, but at the temps you mentioned - you're just shocking them. They'll take longer to get going, but they're not dead. Six hours isn't much time and you won't always see much activity with some starters...

Nurmey 05-28-2008 12:11 AM

Water above 120 will critically injure your yeast. 95 isn't going to damage the yeast but it might put off some less the favorable flavors.

daholl01 05-28-2008 12:37 AM

The off flavors would just be in the starter wort, correct? If I decant most of it before pitching it wouldn't continue to impact the yeast as it ferments my beer.

Soulive 05-28-2008 01:02 AM

Quote:

Originally Posted by daholl01 (Post 692160)
The off flavors would just be in the starter wort, correct? If I decant most of it before pitching it wouldn't continue to impact the yeast as it ferments my beer.

Yeah if you decant you should be good. Even if you don't its not too much liquid to ruin the batch...

BigKahuna 05-28-2008 03:03 AM

Quote:

Originally Posted by Nurmey (Post 692125)
Water above 120 will critically injure your yeast. 95 isn't going to damage the yeast but it might put off some less the favorable flavors.

+1....120 is the killer

I rehydrate yeast in 90+ degree watter all the time...maybe I just expect the flavor?

Nurmey 05-28-2008 03:12 AM

Quote:

Originally Posted by BigKahuna (Post 692317)
+1....120 is the killer

I rehydrate yeast in 90+ degree watter all the time...maybe I just expect the flavor?

BK, I was talking about 95 wort when I mentioned flavor, not rehydrating in water. I always wake my yeast up in a nice warm 90 bath of water.

Tonedef131 05-28-2008 03:26 PM

I have racked 130F wort onto a yeast cake accidentally and thought for sure I killed off the yeast. I stuck the whole lot into the fridge and it was into the 70s within two hours and bubbling away happily. I am actually drinking that batch presently and it is fantastic.

DISCLAIMER: I do not condone this nor do I think it is a good idea, I told this story simply to show that yeast is quite a bit more resilient than we give it credit for.

Nurmey 05-28-2008 03:38 PM

Quote:

Originally Posted by Tonedef131 (Post 692717)
I have racked 130F wort onto a yeast cake accidentally and thought for sure I killed off the yeast. I stuck the whole lot into the fridge and it was into the 70s within two hours and bubbling away happily. I am actually drinking that batch presently and it is fantastic.

DISCLAIMER: I do not condone this nor do I think it is a good idea, I told this story simply to show that yeast is quite a bit more resilient than we give it credit for.

According to the Master Baker at LeSaffre yeast 140 is the death toll for yeast, however, 120 is the injury point. I'm not too surprised that your yeast survived at 130 but it was not a kind thing to do to it. :p

Franzi 05-28-2008 07:20 PM

What about on the opposite end of the spectrum? How cold is too cold?


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