Bread Basics

Leavened vs. Unleavened Bread

• Leavened bread contains a fermenting agent such as yeast, sourdough, or baking soda, which produce gases during the making of bread that cause it to rise. Leavened bread is widely believed to have been invented by the Egyptians, and then spread by the Greeks and Romans. Most bread eaten in the West is leavened.
• Unleavened bread does not contain a fermenting agent. As a result, the bread does not rise and instead remains flat. Examples of unleavened bread include the Middle Eastern pita, the Indian chapati, and the tortilla.
   
  

Leavening Agents

• Sourdough: When Egyptians first began to make leavened bread, they relied on spontaneous fermentation of bread dough by the wild yeast spores and bacteria present in the air. Over time, people learned to leave some of the dough fermented in this way unbaked. This preserved fermented dough, called sourdough, is then used to prepare new dough for baking. If cared for correctly, sourdough can be kept for years, even centuries. Today, many people still keep sourdough for bread-making purposes. As its name suggests, bread made from sourdough has a slightly sour taste.
• Baking soda: The use of baking soda as a leavening agent began in the late 18th century in the United States. Unlike yeast, which leavens bread through the biological process of fermentation, baking soda leavens through a chemical process and is activated by the heat of the oven.
• Yeast: Modern technology allows for the industrial production of yeast, which is dried or compressed and then packaged. Yeast allows bakers to produce bread far more quickly than sourdough does and also produces a higher rise in the bread. Yeast can be bought in nearly any supermarket and is the leavening agent used most often by bread bakers.

Types of Bread