Yeast (levadura)

YEAST
Yeast is a microscopic fungus and very little that exist around us in the land, plants and even in the air. The use of this fungus is too old that it´s calledthe oldest plant cultivated by man.
* There are different types of yeast, but most of the yeast that are cultivated, belong to the genus “Saccharomyces”.
* Yeasts have been used sinceprehistoric times in the production of bread and wine.
* Archaeological investigations indicate that bread was born in ancient Egypt . They tought that because they found instruments for the processingof yeast to make bread.
* They also found drawings of more than 4 thousand years old of bakery and breweries.
* To make the bread, the Egyptians used wheat grains, but quickly, they beganto experiment with different ingredients such as honey, eggs, seeds and spices.
* They used to make their breads in different ways.
* Some of these breads were made for themselves, so thatthey could eat them, while others were specially cooked for celebrations or rituals.
* The application of scientific results to these processes only started in 1676, when Anton Leeuwenhoekdeveloped the first microscope. Only after this discovery was possible to investigate the action of yeast in bread making and other processes.
In 1859, Louis Pasteur first discovered how yeast works infermentation processes.
* Yeast has different uses: as a source of vitamin B, in production of antibiotics and steroid hormones, and as food for animals and humans.
* The most important type offermentation is alcoholic.
* Generally, the fermentation causes the decomposition of organic substances very complex to more simple. (This is called catabolic process).
* Since the 80´s,people have made great advances in instrumentation and they have also invented more techniques in the processes of fermentation of yeast, especially those working in the food industry, biotechnology and...