Upper temp limit for Yeast Starter?

[WissahickonBrew]

Hello all<

I recently acquired a stir plate WITH a heat plate combo. The heat plate can get VERY hot and I have a hard time controlling the heat setting so the solution is below 100 degrees F. I barely move the dial to the on position and the best I can hold a steady temp is at about 84 - 90. (this is in a basement with ambient temp of about 64 F).

Can most ale yeasts tolerate up to 100 F? Is it actually beneficial?

Thanks all!

 

[sandyeggoxj]

Just bring the starter upstairs. You want your starter at 70-75. The fermented beer will be decanted prior to serving.

Making a starter at 100 will stress the yeast, or kill it.

 

[WissahickonBrew]

That's what I was afraid of!

 

[WoodlandBrew]

Yeast can tolerate temperatures as high as 105°F and they do propagate quite rapidly. However bacteria also thrives at higher temperatures. It's better to keep the temperature lower.

Some details here:
http://www.jstor.org/discover/10.23...628855903&uid=3739696&uid=2&uid=3739256&uid=4


This paper suggests that 30°C (86°F) ideal to maintain viability:
http://link.springer.com/article/10.1007/s00253-009-1885-z#page-1

 

[WissahickonBrew]

I thought originally that yeast had a tolerance for higher than expected temperatures. I was concerned if the hot plate creeped up before I checked would it kill my yeast!

Thanks for the links but the scientific text was a little beyond me.

Yeast can tolerate temperatures as high as 105°F and they do propagate quite rapidly. However bacteria also thrives at higher temperatures. It's better to keep the temperature lower.

Some details here:
http://www.jstor.org/discover/10.23...628855903&uid=3739696&uid=2&uid=3739256&uid=4


This paper suggests that 30°C (86°F) ideal to maintain viability:
http://link.springer.com/article/10.1007/s00253-009-1885-z#page-1

 

[WoodlandBrew]

In a nut shell 30°C (86°F) is good for propagation. You don't want it to get above 40°C (104°F) for healthy yeast.

15°C to 30°C is fine for propagation as well. It's just slower at lower temperatures.

 

[trentm]

While 86F is the standard and optimum for lab propagation and increase growth, it may, according to "Yeast" be high enough to "...negatively affect the viability and stability of the resulting yeast. Another problem with very rapid growth or excessive growth is that it can result in weaker cell membranes due to lower un-saturated fatty acid concentrations." The book goes on to say 65 to 75F is a good rule thumb, perhaps a little warmer for ales and a little cooler for lagars.

I think a stir plate heater is not really designed for culturing, instead for heating liquids where a suspension needs to be maintained. That said, I wonder if it could be used as such by connecting it to a temperature controller with the probe in the liquid. Keeping in mind that temp fluctuations are not ideal for yeast.

 

[WissahickonBrew]

The thought crossed my mind if I was confident enough to remove the heat/stir plate bottom and intercept the wires from the heat control knob to a thermocouple contoller. I might try it at some point.

While 86F is the standard and optimum for lab propagation and increase growth, it may, according to "Yeast" be high enough to "...negatively affect the viability and stability of the resulting yeast. Another problem with very rapid growth or excessive growth is that it can result in weaker cell membranes due to lower un-saturated fatty acid concentrations." The book goes on to say 65 to 75F is a good rule thumb, perhaps a little warmer for ales and a little cooler for lagars.

I think a stir plate heater is not really designed for culturing, instead for heating liquids where a suspension needs to be maintained. That said, I wonder if it could be used as such by connecting it to a temperature controller with the probe in the liquid. Keeping in mind that temp fluctuations are not ideal for yeast.

 

[72hw]

How did this turn out - were you able to retire the hot plate? My problem today was an unexpected heat spike in my home. Ambient temp shot up to 84 F so the starter I had going was around 91-ish when I got home. Additionally I had not realized the remarkable amount oh heat my ancient stir plate was producing! I am seriously thinking about trying to rig a thermo couple with some kind of Peltier cooling jacket on my 3L flask to avoid this going forward... After replacing the stir plate that is!

Has anyone here done something similar?