What is Yeast and How Does it Work?

 

Everyone loves delicious bread, but many people do not realize how important yeast is in the process of making bread. If we didn't have yeast we wouldn't have a lot of the things we enjoy today such as rising bread, wine, whisky, or beer. Although yeast is so integral to the food culture of our world many people do not know much about yeast. This article will describe what yeast is and how it works.

Yeast is a "one celled plant" that is so small when alone you need a microscope to see it (Leokum, 1986, p.184). I know yeast is small, but I can see it every time I use it to bake bread; how is this possible? Yeast may be one celled, but it grows in "colonies" (Leokum, 1986, p.184). Yeast is a valuable part of everyday life. Yeast is almost "colorless," and it is considered a "fungus" because it ddoes not produce chlorophyll or any other means of feeding itself (Leokum, 1986, p.184).

As yeast grows it turns into two substances, and these substances help cause the changes in the foods we use them for. The two sunstances yeast forms are "enzymes" known as "invertase and zymase," and these enzymes "convert starch to sugar and sugar to alcohol, carbon dioxide, and energy" (Leokum, 1986, p.184). This process is known as fermentation and this is what causes bread to rise and juice to turn into wine. Yeast may be tiny, but it has a powerful ability to change things.

Many years ago the Egyptians discovered yeast, and they used it in their bread making, but not everyone else knew about yeast. Bread makers of the past realized that leaving their bread out to rest for a while would provide them with lighter fluffier loaves. They did not know it at the time, but this process worked because yeast strands from the air would get in the bread and cause it to rise. These days bread makers add sugar and yeast on purpose to make rise. We now know that the yeast eats the sugar and turns it into carbon dioxide, and the carbon dioxide forms bubbles inside the loaf. The oven's heat "drives off the carbon dioxide and leaves a dry light loaf" (Leokum, 1986, p.184).

Yeast is an amazing fungus that helps us to enjoy the foods and drinks that we love so every time you sip a beer or eat a sandwich remember the one celled yeast plant and enjoy!

Reference:

Leokum, A. (1986). The Big book of tell me why. New York, NY: Grosset and Dunlap.