Have I accidentally killed the yeast?

[Bayern1987]

I was bottling my beer the other night which was my own version of my beloved Weihenstephaner Hefeweizen using the infamous wyeast 3068 strain and naturally I wanted to harvest this yeast to use in the future. As I was quite drunk at the time as I usually am when carrying out anything to do with homebrew, I was clumsy and careless. After bottling my brew, it was time to harvest my yeast from the fermenter. Whilst following the carefully laid out steps, I boiled my water to be added to the fermenter and mix in with the yeast cake and the trub. Unfortunately, not realising this to the next day I poured the water in whilst it was still boiling hot. My question is has this definitely 100% destroyed all of my yeast or can it still be reused? The yeast settled to the bottom as normal and is sitting in a Mason jar in the fridge... however is it merely inactive or just full of dead cells?

Thanks in advance to you all

 

[myndflyte]

Maybe but maybe not. You could always make a starter and see if becomes active. Then just wash and save that yeast and you'll get a couple more jars out of it.

 

[Bayern1987]

Nice one. Good to know there's a bit of hope. Thanks for your help it is much appreciated

 

[IslandLizard]

Do you have any idea how hot that yeast mixture was after adding the hot water?
How much water did you add, and how much slurry was in there?

 

[Vale71]

If you added boiling water to the yeast cake all that yeast is good for is as a nutritional supplement, sorry.

 

[IslandLizard]

To give you some perspective, dry yeast gets rehydrated at around 90-95F, and many beer yeasts can withstand 100-110F for a long time without any problems.

 

[myndflyte]

Yeah my thought was that maybe there was enough yeast cake there to cool the water down fast enough to not kill all the yeast. You definitely killed some though. Using a starter would confirm you still have live yeast and give you a new healthy culture.

 

[Bayern1987]

The water had been boiled about two minutes prior and there was roughly 1 litre of water going on top of 1 - 2 litres of trub room temperature of around 20 degrees Celsius. I was thinking maybe the change in temperature would balance itself out... will definitely try making a starter to see if it works! Thanks

 

[IslandLizard]

So after adding a liter of 200F water, that slurry ended up somewhere between 110F and 135F depending on having between 1 to 2 liters of trub/yeast cake.
Now some yeast undoubtedly got cooked, while the rest got heated, perhaps overheated. Some of it must have survived the hot bath. Maybe half, maybe a quarter?

Yeast typically multiplies 4-5 times in a batch. So if you killed a quarter to half, you'd have enough to pitch a batch right on top. With a risk of somewhat of an overpitch if as much as half survived.

Yeah, I'd decant (pour off) most of the supernatant (the liquid above the slurry), mix up it up well, get 2 tablespoons (~1 oz) out and make a 1 liter starter with it. That will tell you if it's still viable at all.

 

[Dave Sarber]

THEY CALL ME THE YEASTKILLER.
Havent tried boiling water yet. I have used chlorinated tap water. Once, I added salt instead of sugar. Neither practice is recommended.

 

[hottpeper13]

Maybe it's like the Buffalo Theory and only the weak ones were taken out. Great you tube video BTW.

 

[Bayern1987]

So after adding a liter of 200F water, that slurry ended up somewhere between 110F and 135F depending on having between 1 to 2 liters of trub/yeast cake.
Now some yeast undoubtedly got cooked, while the rest got heated, perhaps overheated. Some of it must have survived the hot bath. Maybe half, maybe a quarter?

Yeast typically multiplies 4-5 times in a batch. So if you killed a quarter to half, you'd have enough to pitch a batch right on top. With a risk of somewhat of an overpitch if as much as half survived.

Yeah, I'd decant (pour off) most of the supernatant (the liquid above the slurry), mix up it up well, get 2 tablespoons (~1 oz) out and make a 1 liter starter with it. That will tell you if it's still viable at all.

Gentleman. I'm going to test it out tomorrow
Thanks for advice

 

[bracconiere]

don't people use dead yeast as nutrients? if 25-50% survived.....? lol

 

[BruceH]

don't people use dead yeast as nutrients? if 25-50% survived.....? lol

Exactly what I was thinking.

 

[Jayjay1976]

Just buy a fresh pack of yeast. Why risk your next batch over a few bucks? I used to drink while brewing and make silly mistakes, now I wait until the wort chiller is running to have a celebratory shot and a beer. No more stupid mistakes. YMMV.