yeast plants
Yeast plants are growing in the dough this baker is mixing. The small
photo shows how growing yeast cells look under a microscope.
The baker’s plant
If it weren’t for a plant called yeast, we couldn’t have the kind of
bread we eat.
Yeast plants don’t look like plants. They look like round drops of
jelly. And they’re so tiny you can see them only with a microscope. They
float in the air everywhere. They don’t do anything until they find a
warm, wet place where there’s just the right kind of food. And bread
dough is just such a place.
Bread dough is made by mixing flour and water into a warm, wet paste. To
this is added sugar, which is the yeast plants’ favorite food. So when
the yeast plants get into bread dough, things start happening!
Here’s what happens. When a yeast plant takes in
food, it swells up and splits into two new plants! Then, each new plant
takes in food, swells up, and splits in two! Soon, there are millions of
new yeast plants!
As all these tiny plants take in sugar, they change part of it to a gas.
This gas causes many little bubbles to form inside the dough. This makes
the dough swell up. When the dough is baked, all the bubbles fill with
air. Then the bread is light and airy. But without yeast to change the
sugar into gas, the dough won’t swell up.
Long ago, people let the dough sit in a warm place so that yeast plants
would get into it. Today, bakers don’t have to wait for this to happen.
They buy yeast in packages and mix it into the dough.
When the dough is baked, the bread is light and airy.
Grow a jar of yeast
You will need:
1 packet of yeast
1 tablespoon of sugar about 3/4 cup of warm water a glass jar
Dissolve the sugar in the water. Sprinkle the yeast on top. Leave the
jar in a warm place.
As the yeast plants begin to use the sugar for food, the jar will fill
with foam.
The yeast plants cause the foam by changing part of the sugar into
carbon dioxide.
