Final answer:
The five basic categories of yeast bread are Lean Dough, Rich Dough, Sweet Dough, Laminated Dough, and Hearth Dough. Artisanal breads historically used wild yeasts that were unreliable, often leading to discarded batches. 'Saccharomyces cerevisiae', or baker's yeast, is now used for fermentation, aiding in bread rising and serving as a vital research model.
Step-by-step explanation:
The five basic categories of yeast bread are Lean Dough, Rich Dough, Sweet Dough, Laminated Dough, and Hearth Dough. Lean Dough has low fat and sugar, Rich Dough contains higher amounts of fat, eggs, and sugar, Sweet Dough is known for additions like fruits and spices, Laminated Dough includes layers of butter, and Hearth Dough is baked without pans resulting in a crispy crust.
Historically, artisanal breads were produced by capturing wild yeasts from the air. This process could be long and laborious because it involved a great deal of unpredictability. Many batches had to be discarded due to the unreliable nature of the wild yeasts, which might not always ferment properly, leading to spoiled or unsatisfactory bread.
Yeast plays a crucial role in the quality of the bread. Saccharomyces cerevisiae, a single-celled fungus also referred to as brewer's or baker's yeast, is central to the bread-making process. Yeast ferments the sugars in the dough, producing carbon dioxide gas, which causes the dough to expand and become light and fluffy upon baking.
Aside from their beneficial use in food production, some yeasts can also cause food spoilage and even diseases such as vaginal yeast infections and oral thrush. However, yeasts such as baker's yeast are invaluable for their roles in fermentation and in biological research, functioning as a model organism in a variety of studies.