Yeast is used in various products and the fermentation process occurs between 70 and 115 degrees Fahrenheit. There are some products in which yeast begins to ferment at both higher and lower temperatures.
Yeast is a fungus that requires the presence of certain sugars or starches and a moist environment in which to grow. It is a primary ingredient in a number of food and beverage items, including bread, wine and beer.
Yeast growth is an exothermic process, meaning it generates heat itself. However, yeast requires a warm environment in which to thrive and the temperature varies, depending on the product. Yeast grows well between 110 F to 115 F but between 80 F and 95 F is ideal for bread. Red wine yeast grows best between 77 F and 86 F while certain beer yeasts begin to ferment at 70 F.