Yeast

From Lunchplatter.com WIki

What is yeast?

Yeast is a fungus, a member of the plant family. Yeast exists on plants, in the air, in soil, and in and on humans and animals. Yeast metabolize simple sugars and produce alcohol and carbon dioxide through the process of fermentation. Different strains of yeast are used for different processes, such as brewing, baking, oenology and distillation.

During fermentation the production of carbon dioxide is what gives beers and champagnes their effervescent style, and what makes dough rise to its fluffy goodness.

Yeast for bakers

Yeast In the 1860's Louis Pasteur discovered how bread is leavened and how yeast "works". A particular strain of yeast named Saccharomyces cerevisiae was found to be an excellent leavener for bread and one that could be easily manufactured. Whether you use fresh (compressed) or dry yeast (either regular active dry yeast or instant dry yeast), you are using strains of S. cerevisiae that have been engineered, manufactured and packaged for commercial and home use to be predictable, reliable and fast-acting.

Yeast in the wild

Yeast that is freely floating about in the air or on the surface of grains, fruit or vegetables or in soil. As opposed to commercial bakers yeast wild yeast are strains of Saccharomyces exigus including some varieties of Candida such as C. krusei and C. milleri.