Expert: Chris Bushman - 9/5/2010

Question
Hello, I'm very new to home brewing and made my very 1st batch just a couple of hours ago.

There where no clear instruction with my kit stating the temperature to pitch the yeast, it basically said boil 3 litres of water, dissolve the extract and then top the fermentor up to the 23 litre mark.

I took a temperature reading and it was 38 degrees C (100.4f), since making my batch I have read about pitching the yeast at around 21 degrees C.

Have I killed my yeast stone dead?

Hope not! but have to start somewhere :)

Regards

Mark Thompson

Answer
By the time you read this, your question will already have been answered. Chances are, your brew is happily bubbling away.

Pitching at lower temps is often a good idea, but 38C should not be a problem with killing yeast. I have several packets of dry yeast out in my fridge and one of them suggests rehydrating the yeast in water that is 38C-41C and another suggests 30C-35C.

High fermentation temps produce more fruity esters than lower fermentation temps. That's one reason why ales are more fruity than lagers. If you pitch high, and then bring the temp down slowly, it can skew the flavor profile toward the fruity side.  If you pitch at the desired fermentation temp (like 21C) the ester production is more controllable and predictable.

Since you mentioned 21C, you are probably brewing an ale and a few hours at the higher temp would probably go unnoticed. If you were brewing a lager, you would probably be fermenting at 10-12C, and a few hours at the higher temp could have a bigger effect on the flavor.

I'm sure your first brew will be great. Good luck on your new hobby, Mark!

Chris Bushman
Colfax, California, USA