Role of yeast in bread?
Reveal answer
Ferments sugar → CO₂ → dough rises.
Key words: CO₂
6(a) FOOD PRODUCTION · RECALL
6.5 Yeast and bread
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What happens to ethanol in bread?
Reveal answer
Evaporates during baking.
Key words: evaporates
Why leave dough somewhere warm?
Reveal answer
Yeast enzymes work faster.
Key words: enzymes
Why add sugar to dough?
Reveal answer
Food for yeast respiration.
Key words: food
What is meant by the term yeast?
Reveal answer
A single-celled fungus used in baking and brewing.
Key words: yeast
What is meant by the term proving?
Reveal answer
Leaving dough in a warm place to rise.
Key words: proving
Stages of bread making, Mixing and kneading. What happens? Role of yeast?
Reveal answer
What happens: Ingredients combined; gluten network forms. Role of yeast: Yeast mixed through dough.
Key words: Mixing and kneading
Stages of bread making, Proving (warm). What happens? Role of yeast?
Reveal answer
What happens: Dough rises. Role of yeast: Anaerobic respiration releases CO₂ bubbles.
Key words: Proving (warm)
Stages of bread making, Baking. What happens? Role of yeast?
Reveal answer
What happens: Bread sets; ethanol evaporates. Role of yeast: Yeast killed; respiration stops.
Key words: Baking
True or false, and why? “Bread rises because yeast produces oxygen.”
Reveal answer
False. It produces carbon dioxide.
True or false, and why? “Bread contains a lot of alcohol.”
Reveal answer
False. The ethanol evaporates during baking.
True or false, and why? “The hotter the proving temperature, the faster the rise.”
Reveal answer
False. Above the optimum, yeast enzymes denature and the yeast may be killed.
Which type of respiration does yeast carry out in rising dough?
Reveal answer
Anaerobic respiration (fermentation).
Key words: anaerobic
Give the word equation for anaerobic respiration in yeast.
Reveal answer
Glucose → ethanol + carbon dioxide.
Key words: ethanol
Why does dough rise less when it is made with very hot water?
Reveal answer
Heat denatures the yeast enzymes or kills the yeast → less CO₂ released.
Key words: denatures