Book 9, Question 24
Why Does Yeast Need Sugar or Starch?
Yeast needs sugar or starch because yeast are tiny living things that eat it! They eat sugars and release carbon dioxide gas and flavor. The gas bubbles make dough rise.
More fun facts
- Yeasts feed on sugars and starches, which bread dough has lots of.
- When yeast eats sugar and turns it into energy, it gives off carbon dioxide gas.
- That gas makes bread rise, though more slowly than baking powder or baking soda.
- Enzymes already in flour break starch into sugars that yeast can eat.
- Wheat kernels contain an enzyme called amylase to turn starch into sugar when the seed starts to sprout.
Sources: Scientific American, Exploratorium, Scientific American
Questions kids ask
What happens to yeast with no sugar?
Without sugar to eat, yeast cannot make much carbon dioxide, so dough will not rise well.