Yeast in the mail - am I screwed?

[the-adjunct-hippie]

Apparently my 10 packets of Saffale US05 arrived in my mailbox yesterday. We have been out of town and will arrive back tonight. It was 85 and storming yesterday and today it's 90. Are my yeasties dead?

 

[brewbama]

Though not ideal, I’ll bet the yeast is alive and well.

 

[ancientmariner52]

Apparently my 10 packets of Saffale US05 arrived in my mailbox yesterday. We have been out of town and will arrive back tonight. It was 85 and storming yesterday and today it's 90. Are my yeasties dead?

Remember, these little guys lived in the wild for many millions of years before we started messing with them. Those would not be good fermenting temps, but for dormant dry yeast, I'll bet you'll be just fine. I suppose you could sacrifice a packet for a test, but personally I wouldn't bother.

 

[Hoppy2bmerry]

I agree they are likely okay, bread yeast generally sits on supermarket shelves now after sitting in hot warehouses and delivery trucks.

 

[Northern_Brewer]

~85F is actually about the optimal growth temperature for yeast, and even wet yeast should survive up to ~110F, never mind dry. At least for ale yeast, lager yeasts die below 100F. The only reason we ferment at lower temperatures is off flavours, not yeast survival. Think of wild yeasts living dried up on the bark of trees and vines in Mediterranean climates.

So your US-05 will be fine. It’s not ideal, viability will be affected by long term storage at those temperatures, but as a one-off it’s fine.

 

[mabrungard]

They should be fine. A few cells probably perished due to the heat, but not enough to really matter. While those packets might have been subject to warmer than ideal storage temperatures during their transport, I keep my packets in the refrigerator to improve their lifespan.

 

[the-adjunct-hippie]

Thanks everyone!