40: Yeast Fermentation Animation Video
Transcript:
Technique: Yeast Fermentation
Yeast is one type of leavening agent used in the bakeshop. It is typically used to make breads and rolls, whereas chemical leaveners, such as baking soda, are used for cakes, cookies, or pastries.
Yeast is a living microscopic plant that feeds on carbohydrates and produces a gas called carbon dioxide and an alcohol called ethanol.
Fermentation happens most quickly at temperatures between 90°F and 110°F (32°C and 43°C). When this process takes place in bread dough, the gas bubbles cause the dough to expand.
Temperatures of 130°F to 140°F (55°C to 60°C) will kill yeast. As the temperature of the dough increases during baking, the high temperatures kill the yeast and cause most of the alcohol to evaporate. As the yeast dies, the gas production ceases.
Continued baking causes the dough to become firm and promotes a beautiful brown crust.