29 December 2012

#35 Using yeast to make bread and beer

Yeast is a single celled, microscopic fungus which uses sugar as food. It is widely used in food industries such as baking and brewing.


  • Mix yeast with flour, sugar and H2O to make dough.
  • Kept dough warm: Yeast respires sugar to produce CO2This make dough rise.
  • When the bread is baked, the yeast is killed.



  • Yeast respires sugar (from juice, grain) to form ethanol and CO2.
  • The ethanol makes the drink alcoholic, carbon dioxide gives the drink its fizz.
  • The process is called fermentation.

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