How to rehydrate dried yeast properly
Posted by     08/20/2014 08:38:00    0 Comments

How to rehydrate dried yeast properly

Yeast rehydration is the process whereby dry yeast is rehydrated and “brought to life” from its dormant passive state.

The “standard” method of rehydration is as follows:

Image from Lallemand

  • Heat water (10 times the weight of the yeast) to a temperature of between 35 and 40 °C
  • If the yeast is coming from a fridge, allow it to slowly heat up to room temperature before rehydration.
  • Add and dissolve yeast activator in water (only use activator on very strong sugar solutions i.e. Bx > 26 to be fermented)
  • Sprinkle the yeast on top of the water and stir slightly to wet all yeast.
  • Let it stand for 16-20 minutes. (The yeast will now "bloom")
  • Gently stir to break up any clumps.
  • Pitch the yeast (add to the mash) at a mash temperature not less than 10 degrees colder than the rehydration water (otherwise the yeast goes into shock).

Don't wait longer than the 16-20 minutes before pitching the yeast as the yeast will slowly start dying off as it wants to start feeding but there are no nutrients to feed on.

Also, don't add any nutrients or other additives (like di-ammonium phosphate - DAP) to the rehydration water as it is toxic in high quantitiies to the yeast. The yeast requires only clean water to rehydrate (or actvator when doing strong sugar washes).

When making a yeast starter do not allow the Brixx value to be higher than 26 (when NOT using yeast activator) or higher than 34 (when using yeast activator)

Also read the article on "How to store yeast and nutrients"

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