Yeast Pitch Vs. Fermentation Temperatures

[geoffny25]

A few hypothetical questions,

If ale yeast is pitched at temperatures between 90-100F, but the fermenting vessel is cooled to 65 degrees using a damp t-shirt and an ice bath over the next few hours, what off flavors will this cause?

At what temperatures do yeast start to die?

While not wanting to actually conduct this experiment for fear of ruining a beer, it would be interesting to hear the response.

Thanks,

Geoff

 

[gtpro]

providing the yeast all survive, it shouldnt cause any off flavors as long as its at a good temp for the actual fermentation stage.

EDIT: I guess if that much heat stresses the yeast out, which it may then you could have off flavors.

 

[permo]

I wouldn't chance it, I almost always pitch between 70 and 75 degress and stick the fermenter in 60 ambient until fermentation starts and then adjust temperature from there. I think 100 degrees might be putting the yeast in jeapordy, no sure though.

 

[jkarp]

It's an interesting question worthy of some discussion. Dr. Chris White (White Labs) said here the following:

The lag phase can be carried out at a higher temperature than the rest of fermentation because very little flavor compounds are produced. Ethanol production is also very limited, therefore ester formation is not a concern. Some brewers begin the lag phase for ales at 72-75F, and complete the fermentation at 68F. This can be done with success for lagers too, with starting the lag phase at 72-75F and lowering the fermentation temperature to 50-55F.

This is quite contrary to the opinion of many homebrewers, including award winning ones like Jamil...

 

[milwaukee]

That's super interesting about the possibility of a slighty higher (not yeast-lethal) temp during the lag phase. I guess it makes sense since the yeast are just getting their metabolic processes fired up.

My question would be whether or not introducing the yeast at a higher temp than the fermentation temp would create a longer lag time... which is obviously not a huge deal, but not desired.

 

[scorchingice]

A few hypothetical questions,

If ale yeast is pitched at temperatures between 90-100F, but the fermenting vessel is cooled to 65 degrees using a damp t-shirt and an ice bath over the next few hours, what off flavors will this cause?

At what temperatures do yeast start to die?

While not wanting to actually conduct this experiment for fear of ruining a beer, it would be interesting to hear the response.

Thanks,

Geoff

If you pitch the yeast at 90-100 degrees the yeast will not die immediately upon pitching.

If you pitch the yeast at 90-100 degrees and maintain that temperature for a period of time, the yeast are going to die. The reasoning behind this is simple. Yeast produce a lot of heat while fermenting.

I believe the reason the pitch temperature is so low is because it is a "Safe Zone" It is a confirmed tested temperature that the yeast can be pitched with no worry of losing any to heat temperatures.

If you pitch at 90-100 degrees you would be fine in theory as long as the temperature was reduced within an hour.

For a nice yeast / temperature reading on with a lot of information try THIS LINK.

 

[geoffny25]

fascinating, thank you