The Exploratorium is more than a museum. Explore our online resources for learning at home.

The Accidental Scientist: Science of Cooking
Yeast is Fussy About Temperature

From The Inquisitive Cook, by Anne Gardiner and Sue Wilson with the Exploratorium (Henry Holt and Co., 1998).

300° F–400° F (150° C–205° C)
Surface temperature of a browning crust.

200° F (100° C)
Interior temperature of a loaf of just-baked bread.

130° F–140° F (55° C–60° C)
Yeast cells die (thermal death point).

120° F–130° F (49° C–55° C)
Water temperature for activating yeast designed to be mixed with the dry ingredients in a recipe.

105° F–115° F (41° C–46° C)
Temperature of water for dry yeast reconstituted with water and sugar.

100° F (38° C)
or lower When yeast is mixed with water at too low a temperature, an amino acid called glutathione leaks from the cell walls, making doughs sticky and hard to handle.

95° F (35° C)

Temperature for liquids used to dissolve compressed yeasts.

80° F–90° F (27° C–32° C)
Optimum temperature range for yeast to grow and reproduce at dough fermentation stage.

70° F–80° F (21° C–27°C)
Recommended water temperature for bread machines.

40° F (4° C)
Recommended refrigerator temperature. Used directly from the fridge, yeast is too cold to work properly.

close this window