How Does Yeast Work?How Does Yeast Work?How Does Yeast Work?How Does Yeast Work?

By Ginny P7

August

What is yeast?What is yeast?What is yeast?What is yeast?

• Yeast is a “one celled plant“.

• It is so small you need a

microscope to see it.

• Yeast may by be one celled

but it grows in "colonies“.

• Yeast is the active agent that

makes bread rise.

• Yeast is a fungus. Saccharomyces cerevisiae

How yeast was discovered ?How yeast was discovered ?How yeast was discovered ?How yeast was discovered ?

• Many, many centuries ago the Egyptiansdiscovered 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 dough out to air for a while would provide them with lighter loaves. 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 & yeast on purpose to make it rise. We now know that the yeast eats the sugar & turns it into carbon dioxide & the carbon dioxide forms bubbles inside the loaf -leaving a dry, light loaf.

• Yeast comes in

many species.

• The one used for

baking and

brewing is

Saccharomyces

cerevisiae.

ProcessProcessProcessProcess !!!!

• Like many fungi types, yeast responds to warm water, which awakens the tiny cells.

• Then when exposed to the sugars in flour, it eats the sugar, digesting it. This eating process goes on for a few hours.

• As the yeast is feasting, it begins to release gas bubbles of carbon dioxide, and small amounts of ethanol alcohol.

• These bubbles, trapped in the bread dough, cause the bread to inflate. You’ve got to let the fungi work for a couple of hours in order to sufficiently rise dough.

Process 2!Process 2!Process 2!Process 2!

• Once dough has risen, not all of the cells are quite dead. When baked, however, the heat makes remaining cells go berserk, madly eating the sugars and releasing carbon dioxide prior to dying from the heat.

• There are a few things that can stop these fungi from their natural function. Too much salt can halt its rising action. Therefore bread recipes always contain a little salt & a little sugar for balance.

• Butter, oil & animal fats can also stop the fungi, you’ll see that breads that have butter in them, mostly salted butter may not have the same rise due to the butter’s presence.

References !References !References !References !

• http://www.associatedcontent.com/article/1968318/what_is_yeast_and_how_does_it_work.html

• http://thenewcook.com/2008/11/how-does-yeast-work/

• http://answers.ask.com/Food_and_Drinks/Food_and_Cooking/how_does_yeast_work

• http://thenewcook.com/2008/11/how-does-yeast-work/

• http://www.google.co.uk/imgres?imgurl=http://www.buzzle.com/img/articleImages/372993-27430-16.jpg&imgrefurl=

• http://www.google.co.uk/imgres?imgurl=http/

• http://www.google.co.uk/imgres?imgurl=http://

• http://www.google.co.uk/imgres?imgurl=http://