Yeast dough

Why

The yeast cells break down sugars from the flour into carbon dioxide and alcohol; the gas, trapped in the gluten network, inflates the dough, while the by-products give it flavour. They work best at roughly 25–35 °C, slow down in the cold without dying, and begin to die from about 50–55 °C, so milk that is too hot kills the yeast before the dough ever reaches the oven. Salt slows fermentation and strengthens the gluten; plenty of sugar draws water away from the yeast and plenty of fat coats it, so sweet, buttery yeast doughs take longer to rise. A longer, cooler rise, such as overnight in the fridge, gives the dough more flavour, whereas over-proofed dough runs out of strength, collapses and smells sour and boozy.

How to do it

• Warm the milk or water only until lukewarm, about body temperature – it mustn't feel hot on your wrist.
• Stir fresh yeast with a little lukewarm liquid, a teaspoon of sugar and some flour, and let the starter get going.
• Mix the salt into the flour, not straight into the starter.
• Leave the dough to rise covered in a warm, draught-free spot until it has roughly doubled in size.
• Give sweet doughs rich in butter and sugar more time to rise, or add a little more yeast.
• Check the rise with a finger: the dent should spring back slowly; if it stays, the dough is over-proofed.

If it goes wrong

If the starter didn't bubble, the yeast was old or scalded – make a new one with fresh yeast. Dough that won't rise should go somewhere warmer (not directly on a radiator) and be given time. Knock back over-proofed dough briefly, shape it and let it rise again for a short while; it will be a little denser, but it will still bake.