Fresh, active dry or instant yeast?
How fresh, active dry and instant yeast compare, how to convert between them, and why biga recipes use such small amounts.
Biga recipes, especially Italian ones, usually give fresh yeast. You can use any of the three common types. Only the amount changes.
Converting
| Yeast | Amount for 1 g of fresh yeast |
|---|---|
| Fresh (compressed, cake) | 1 g |
| Active dry | about 0.4 g |
| Instant dry | about 0.33 g |
Gabriel Reboul’s recipes match this: 3 g of fresh yeast becomes 1.3 g of dry yeast in one recipe, and 3–4 g becomes 1.5 g in another.
The calculator works in fresh yeast internally and converts to the type you choose.
Small amounts, so weigh carefully
A biga uses very little yeast: around 3–4 g of fresh yeast per kg of flour, and around 1 g in the final dough. With instant yeast that’s about 1 g and 0.3 g. A kitchen scale that reads to 0.01 g (a jewellery scale) is a cheap, worthwhile tool. A 1 g mistake can be a 30% mistake.
Using each type
- Fresh yeast is soft and crumbly. Dissolve it in some of the water. It keeps for about two weeks in the fridge; it should smell pleasant, not sour, and crumble rather than turn sticky.
- Active dry yeast is usually dissolved in some of the water first. Check the packet.
- Instant dry yeast can go straight in with the flour or water.
Seasons
Gabriel adjusts the yeast with the weather: a little more when it’s cold, a little less in summer. That’s the same thing the calculator does when you change the temperature. Warmer means faster, so less yeast for the same time.