Fermentation Temp

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npenno

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Hi All,

At what temperature will yeast be killed? I accidentally pitched US05 last night at 35 degrees. It was down to 23 within 12 hours.

Will this cause any major change in the beer? The brew was DrSmurto's Golden Ale.

Thanks,

Nick
 

Jace89

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Any signs of fermentation? If it hasn't killed them it could produce alot of off/undesired flavors. I'd say taste it and check the gravity might turn out drinkable still.
 

Lecterfan

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Fermentis 'tips and tricks' type .pdf that was posted on here somewhere ages ago advises rehydrating ale yeasts in water up to 29c. From memory Danstar Windsor says to use 30-35c???

Regardless, you will not have killed all the yeast...did you rehydrate or not (rehydrating theoretically should reduce the number of shocked/dead cells)? As Jace said, they may well produce some undesirable flavours while madly reproducing in the warm, sugary wort.

I'd certainly still see the brew out to the end and see what it tastes like once kegged/bottled.
 

Diesel80

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My last beer the yeast was inadvertantly pitched into wort that was 34 degress, but cooled to 23 in about 8 hours, no off flavours detected fermentation was off and going in 5 hours.

I used Notto yeast. Have no experience with US05.

Still early days yet.
Was the yeast rehydrated or just sprinkled in?

Cheers,
D80
 

hughman666

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assuming it was cooling from 35c down to 23c at an even rate over 12 the hours, your first 6 hours are realistically where your lag time would be happening.

after the first 6 hours your ferment should have started to kick in as you would be going from 29c down to 23c.

let us know how it turns out!
 

npenno

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D80,

I just sprinkled the yeast over the top

Nick
 

QldKev

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I think it will be OK from the initial temps, and be surprised if it threw that much off flavors. Most my cubes are pitched at room temp and thrown into the fridge to get to the correct fermenting temps. Not the perfect world for it, but it helps reduce lag time. You will get away with it in beers like the Golden Ale, but don't do it on really light flavored beers.

I'm more worried are you siting US-05 at 23c for the main ferment?

QldKev
 

npenno

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Hi Kev,

The 23 was still on the way down. The fridge is set at 18 degrees for fermentation.

Regards,

Nick
 

Lurks

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This yeast temperature thing is pretty wide spread...

Dr Cone, the bloke from Danstar Yeast, is on record as saying most yeast strain optimum rehydration temperature is closer to 40C. You can Google that easily enough.

Course one might choose not to believe the lead scientist of a yeast lab with a phd in microbiology... but I can tell you, I rehydrated S-04 at 40C and got a very thin layer of dead cells (high viability), thing went off like a rocket in the fermenter.

You are in zero danger of killing yeast with these temperatures. The thing that kills yeast is pitching it directly onto wort. Not all of it, but a lot of it. Fortunately they put a lot of cells in those dried packets...

I deliberately pitch into wort a bit warmer than then desired fermentation temp - purely because it'll get going faster, which is safer obviously. 99% of the fermentation will occur at the desired temperature so any funny flavours should not, by my inexpert reckoning, be much of a problem.
 

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