Ingredient

Yeast

Yeast is a living organism that eats sugars and produces carbon dioxide and alcohol. Almost everything that goes wrong with it comes down to temperature or to salt, and almost everything that makes bread better comes down to using less of it and waiting longer.

The three kinds

Fresh (compressed)

A moist block. Crumble straight into the flour or dissolve in liquid. Keeps about two weeks in the fridge and freezes. Use roughly twice the weight of dried.

Active dried

Granules that need rehydrating in warm liquid for ten minutes before use. The step is not optional.

Instant (fast-action, easy-bake)

Fine granules that go straight into the flour with no rehydrating. The most convenient and what most modern recipes assume.

Rough conversion

1 part instant : 1.25 parts active dried : 3 parts fresh, by weight.

Sourdough starter

Wild yeast and bacteria rather than commercial yeast. A different thing — see sourdough.

What kills or slows it

• Hot liquid. Above roughly 50°C yeast dies. Water should feel warm to the wrist, never hot. This is the commonest way to kill a batch.
• Direct contact with salt. Salt draws water out of yeast cells. Add them to opposite sides of the flour and mix the dry ingredients before the liquid.
• Too much salt. Around 2% of the flour weight is normal; much more slows fermentation badly.
• Too much sugar. Enriched doughs ferment slowly because sugar draws water away from the yeast. They need more yeast and more time.
• Cold. Does not kill it — it slows it, which is often exactly what you want.
• Age. Dried yeast loses potency on the shelf, especially once opened. Keep an opened packet in the fridge or freezer.

Why less yeast makes better bread

Yeast produces gas, which raises the loaf, and it also produces a wide range of aromatic compounds — as do the bacteria that come along with any long fermentation. Those compounds are what makes bread taste of bread rather than of flour.

A lot of yeast produces the gas quickly and the flavour barely at all. A small amount, given many hours, produces the same gas and a great deal more flavour, because the fermentation has had time to develop.

So the single cheapest improvement to home bread is to cut the yeast substantially and let the dough rise overnight, ideally in the fridge. A quarter of a teaspoon in a standard loaf, risen for twelve hours, makes noticeably better bread than a full sachet risen for one.

Testing whether yeast is alive

1. Put a teaspoon of yeast in a small bowl.
2. Add a few tablespoons of warm — not hot — water and a pinch of sugar.
3. Stir and leave it somewhere warm for ten minutes.
4. It should foam up visibly and smell yeasty.
5. If nothing happens, it is dead and no amount of extra time will fix a dough made with it.
6. This takes ten minutes and saves the four hours you would otherwise spend waiting for a dough that was never going to rise.

Common questions