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I wasn't able to cool down the wort well enough and pitched WLP001 at 85 degF (I know, what a failure...) My home is 82 degrees indoors and the water comes out of the faucet at that temp too. Ran out of ice in the fridge and it was a bad day... Fortunately, I got the temperature down to 75 degrees within the first hour and a half.

Anyways, I was originally planning on washing the yeast to reuse after racking this beer to a secondary. If it was pitched too high, would I still be able to wash and reuse it?

Thanks for your help!

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Did you use a starter? – Matthew Moisen Sep 5 '13 at 7:14
up vote 0 down vote accepted

Whilst you can try to wash and reuse it the yeast will have suffered some heat stress as optimal temp range for that yeast is between 68-73F.

If a yeast did not have a textbook fermentation, I would not try to reuse it unless there was either no other way to get the yeast or unless it was very expensive to just get new yeast. The cost of a new batch of this yeast is nothing compared to the possible loss of a batch of beer.

The trouble is that you wont really know if this batch of beer comes out ok before you would need to re-pitch the yeast as it will only store well in a fridge for a week or 2 but if you do go ahead and harvest some of this yeast, make sure you go through with a starter before pitching it again to give the yeast the best chance.

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That temp range refers to fermentation, not yeast health. Temps over 90F for a long period of time might produce some mutations, but temps as the OP said for a short period if time will have no negative effects on yeast health. Reuse should be no problem. – Denny Conn Sep 5 '13 at 18:22
Reuse will not be a problem. As denny says, the temp range relates to the fermentation profile, not specifically yeast health. They'll be fine at 85°F, you just may get esters/hot alcohol/diacetyl. – mdma Sep 6 '13 at 12:08

You can reuse the yeast - the temperature range top of 73°F is for the recommended fermentation profile.

In the lab, researchers shock the yeast by raising the temperature from 25°C/77°F to 37°C/98°F and holding it there for several hours.

Your brief venture into 85°F was short - 1.5 hours - so if any shock has occurred, it will be a mild one.

But as with any re-use of yeast - always taste the beer you just racked off to look out for any potential problems before considering harvesting the yeast.

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