Very high fermentation temperature

[GrizzlyBier]

I brewed 10 gal of blueberry wheat yesterday. I used 2 packs of Safale US-05 rehydrated. Wort was 68F when I pitched. Then, like a dummy, I put a space heater near it and covered it (my conical) with a blanket. To my chagrin, I woke up this morning and the temp was 93F!! It wasn't fermenting and I assumed I killed the yeasties. At lunch I went to LHBS and grabbed another couple of packets of US-05, went home to re-pitch and it had cooled to 85F and was bubbling away pretty vigorously.

So how bad will this screw up my beer? I don't mind esters but fusel alcohol? What does fusel alcohol taste like?

 

[stickyfinger]

I brewed 10 gal of blueberry wheat yesterday. I used 2 packs of Safale US-05 rehydrated. Wort was 68F when I pitched. Then, like a dummy, I put a space heater near it and covered it (my conical) with a blanket. To my chagrin, I woke up this morning and the temp was 93F!! It wasn't fermenting and I assumed I killed the yeasties. At lunch I went to LHBS and grabbed another couple of packets of US-05, went home to re-pitch and it had cooled to 85F and was bubbling away pretty vigorously.

So how bad will this screw up my beer? I don't mind esters but fusel alcohol? What does fusel alcohol taste like?

fusels smell sort of like acetone or isopropanol, like a solventy aroma. I would think the batch is ruined, but you never know. see what happens when it's done. if you have space, you could try letting the beer age a LONG time and it might come around some. interested to hear if it is ruined after that deviation!

 

[Gameface]

Fusels taste like rubbing alcohol.

If they are there they are also likely to give you a headache if you decide to drink it.

 

[Northern_Brewer]

I assumed I killed the yeasties.

What does fusel alcohol taste like?

The optimal temperature for yeast growth is around 85-90F, and ale yeast can survive over 100F - think of them surviving on tree bark etc in the wild. We only ferment at lower temperatures in order to avoid off-flavours.

Fusels are solventy, they do condition out to some extent. See how it goes, it may not be fatal.

Incidentally, these days Fermentis recommend you don't rehydrate, just sprinkle directly.

 

[GrizzlyBier]

Update on the 93F starting fermentation temp wheat ale:

It's actually quite good. Definitely not a dumper. I may have smelled a strong-ish alcohol smell right before kegging but I've made worse beer. No off flavors, pretty easy drinking.
So maybe I got the temp down fast enough? It seems like the yeast population was pretty healthy and produced an effective fermentation.