Yeast fermentation
Also searched as: proving, proofing, rising, dough rises, fermentation
In short: Yeast eats sugar from the flour and gives off gas and aromas. The gas puffs up the dough, the aromas make the flavour.
Like millions of tiny air pumps that only work when they are warm enough and have something to eat.
Simplified model
Temperature thresholds
4
- 4 °Cfridge: works very slowly
- 24 °Croom: a relaxed prove
- 27 °Cmost active (27–32 °C)
- 55 °Cyeast starts to die
Below 4 °C none of this happens yet. From 4 °C: fridge: works very slowly.
What happens
are living fungi. They turn sugar into carbon dioxide and alcohol and form aroma compounds along the way. They are most active between about 27 and 32 °C; in the fridge they work only very slowly. From about 55–60 °C they die, which is why the rise ends in the oven.
Why it matters
Temperature controls how fast the dough rises. Slow and cool gives more flavour, fast and warm gives more volume in a short time.
Rules of thumb
- A cool, long prove for flavour; a warm, short one when it has to be quick.
- Never put salt directly onto the yeast.
- Fully proved: a finger dent fills back slowly, not immediately and not at all.
Levers
4
Common mistakes
1
- Proving too warm for too long: the network tears and the dough collapses.
In practice
2
Bread
Prove overnight in the fridge: more aroma, a better crust, a more flexible schedule.
Cakes and baking
Braided loaves and enriched yeast cakes rise more slowly, because sugar and butter slow the yeast down.
Sources · 2
- Exploratorium: Yeast and temperature
- Harold McGee: On Food and Cooking (2004), Kapitel Brot, Getreide