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High Fermentation Temps

bobo1898

Grandmaster Brewer
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Brewed an all grain batch with a 1.057 OG. Wort cooled to 68/70. I rehydrated two safale 04 packets and pitched. One day later, vigorous fermentation (expected) but the temp shot up to 79!! Fermentation is known to warm up a bit but 9-11 degrees? It's in a cool basement that is a steady 66.

How concerned should I be? I imagine there may be a lot of off favors.
 
That's a little warm. Depending on the strain, the resulting flavors could be fruity/estery to spicy/phenolic. Whatever the expected flavors of the yeast are, you can expect them to be amplified from warmer fermentation.

The first 48 hours of fermentation are the most vigorous and produce the most heat. I think the yeast's thermal energy is around 170 btus per gallon of wort, per degree plato. A glass or plastic fermenter is a pretty good insulator, as it yeast, itself. Some years ago, a good friend at a large brewery showed me a temperature graph on an 800 barrel fermenter that had a coolant pump go out at night. It was (probably still is) an outdoor fermenter and the ambient temperature that night was about 50F. The fermentation went from 66F to 90F in about 4 hours.
 
Interesting. The yeast already settled out and the kraeusen dropped (also expected from safale 04). Temp has gone down as well (to 70 degrees). Hopefully all is well, but I imagine that it might pretty estery.
 
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