Author Topic: rehydrated dry yeast temperature shock  (Read 1219 times)

Offline Steve Ruch

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rehydrated dry yeast temperature shock
« on: January 16, 2015, 10:17:41 PM »
You're supposed to rehydrate dry yeast at around 100f. Doesn't that get quite a shock when added to 65f wort? Doesn't that increase lag time while the yeast adjusts to the much lower temperature.?
I normally just chuck the yeast in and that works fine for me, but I have a couple of bigger beers (1.080-90) planned and thought it would be a good idea to rehydrate for these beers.
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Offline a10t2

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Re: rehydrated dry yeast temperature shock
« Reply #1 on: January 16, 2015, 10:43:42 PM »
By the time the yeast sits for 15-30 min or whatever the directions call for, it should have cooled to pretty much room temperature.

I'd consider pitching two packs for that Gravity, though, assuming it's a 5-6 gal batch.
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Offline garyg

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Re: rehydrated dry yeast temperature shock
« Reply #2 on: January 16, 2015, 11:22:36 PM »
I've heard a wine kit rep argue that the loss of yeast to temperature sheer is so great that they recommend not rehydrating dried yeast at all.  I think that's a bit extreme and really assuming that most homebrewers/winemakers can't follow good yeast handling practices.  I'd think your best results would be from rehydrating with a rehydration nutrient like Go-Ferm and letting it cool to your wort temp before pitching.  With such a small volume, it shouldn't take that long to cool.
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Offline Steve Ruch

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Re: rehydrated dry yeast temperature shock
« Reply #3 on: January 17, 2015, 04:53:35 PM »
By the time the yeast sits for 15-30 min or whatever the directions call for, it should have cooled to pretty much room temperature.

I'd consider pitching two packs for that Gravity, though, assuming it's a 5-6 gal batch.

That makes sense. It'll be three gallons so one pack should do the job, I just thought it might be a good idea to give the yeast a bit of a head start.
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Offline denny

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Re: rehydrated dry yeast temperature shock
« Reply #4 on: January 17, 2015, 05:21:44 PM »
I've heard a wine kit rep argue that the loss of yeast to temperature sheer is so great that they recommend not rehydrating dried yeast at all.  I think that's a bit extreme and really assuming that most homebrewers/winemakers can't follow good yeast handling practices.  I'd think your best results would be from rehydrating with a rehydration nutrient like Go-Ferm and letting it cool to your wort temp before pitching.  With such a small volume, it shouldn't take that long to cool.

Dan Listermann discovered the same issue with the customers at his store many years ago...15 at least.  So many people were having bad experiences after rehydrating that he started recommending they don't do it.  Apparently that produced much better results.
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Re: rehydrated dry yeast temperature shock
« Reply #5 on: January 17, 2015, 05:53:56 PM »
I'm surprised to hear a recommendation to rehydrate at 100F. While I do boil my rehydration water to help sanitize it, I do let it cool to room-temperature before adding the dry yeast.

I've done unscientific trials on hydrating and not hydrating and have come to the conclusion that I get significantly better performance when I hydrate the yeast. I can understand that you could easily screw up the rehydration process by not properly working with the water, but I still think that we are better off with rehydration. The reduced osmotic stress placed on the yeast due to rehydrating with plain water just makes sense to me. Sugar-filled wort places more osmotic stress on the yeast, and I can imagine, does reduce the overall viability and numbers for the yeast pitch.
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Offline narcout

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Re: rehydrated dry yeast temperature shock
« Reply #6 on: January 17, 2015, 06:08:47 PM »
I'm surprised to hear a recommendation to rehydrate at 100F. While I do boil my rehydration water to help sanitize it, I do let it cool to room-temperature before adding the dry yeast.

They recommend 105 degrees in Yeast, though I think some manufacturers recommend closer to 95 degrees. 

This is interesting though: http://seanterrill.com/2011/04/01/dry-yeast-viability/
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Offline Stevie

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Re: rehydrated dry yeast temperature shock
« Reply #7 on: January 17, 2015, 06:15:59 PM »
I microwave some water for a few minutes covered with plastic wrap on top. I do this while mashing and leave it be until I am ready to pitch.

Offline denny

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Re: rehydrated dry yeast temperature shock
« Reply #8 on: January 17, 2015, 06:40:45 PM »
I've done unscientific trials on hydrating and not hydrating and have come to the conclusion that I get significantly better performance when I hydrate the yeast.

Likewise here, but with the opposite conclusion.  Interesting....
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Re: rehydrated dry yeast temperature shock
« Reply #9 on: January 17, 2015, 08:05:18 PM »

They recommend 105 degrees in Yeast, though I think some manufacturers recommend closer to 95 degrees. 

This is interesting though: http://seanterrill.com/2011/04/01/dry-yeast-viability/

The thing that could easily catch many, is for the water temperature to be too hot and the cells being killed on contact. Without a thermometer, it could be difficult to say the water was cool enough if you aiming for 100 or 105F. You just know its warmer than body temperature. However with certainty, I can tell when water is colder than body temperature. It just seems like an appropriate safety precaution.

I had not seen Sean's work on this subject. Just what I expect from the orange-hatted one. That work points to exactly what I contend, plain cool water is a better method.
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Offline JT

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Re: rehydrated dry yeast temperature shock
« Reply #10 on: January 17, 2015, 08:17:50 PM »
I've heard a wine kit rep argue that the loss of yeast to temperature sheer is so great that they recommend not rehydrating dried yeast at all.  I think that's a bit extreme and really assuming that most homebrewers/winemakers can't follow good yeast handling practices.  I'd think your best results would be from rehydrating with a rehydration nutrient like Go-Ferm and letting it cool to your wort temp before pitching.  With such a small volume, it shouldn't take that long to cool.

Dan Listermann discovered the same issue with the customers at his store many years ago...15 at least.  So many people were having bad experiences after rehydrating that he started recommending they don't do it.  Apparently that produced much better results.
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Re: rehydrated dry yeast temperature shock
« Reply #11 on: January 17, 2015, 09:12:10 PM »
He started out by selling home brew equipment he had engineered and manufactured. He has quite the reputation in the home brew world. And we get to buy from him regularly and drink his Chickow! !!!
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Offline denny

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Re: rehydrated dry yeast temperature shock
« Reply #12 on: January 17, 2015, 09:18:16 PM »
You know Dan all the way on the west coast?!

I've known Dan online for 17 tears and we met in person when NHC was there.
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Re: rehydrated dry yeast temperature shock
« Reply #13 on: January 18, 2015, 12:16:40 AM »
You know Dan all the way on the west coast?!

Anyone who is been brewing for a long time knows Dan.  The home brewing community used to be lot smaller than it is today.  I used one of Dan's false bottoms for years.

« Last Edit: January 18, 2015, 06:52:15 AM by S. cerevisiae »

Offline klickitat jim

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Re: rehydrated dry yeast temperature shock
« Reply #14 on: January 18, 2015, 12:16:47 PM »
My dad made his first batch of beer back in the 50s but I'm pretty sure he doesn't know him.