Fermentation is sometimes performed in a warm place, or a humidity- and temperature-controlled environment. Cooler-than-room or refrigeration temperatures decelerate growth and increase the time interval, while slightly warmer temperatures accelerate growth and decrease the time interval. Too warm a temperature slows growth, while even higher temperatures will kill the yeast. Death of the yeast cells occur in the range of . When cooling a levain or sourdough pre-ferment, if the dough temperature drops below it affects the culture and leads to the loss of a particular aroma in the baked bread.