A Biga is an Italian preferment, which is very stiff. It ferments in the fridge for at least 16 hours and develops during this time a hint of acidity and a complex, nutty flavour. The week acidity helps to improve the gluten network as well.

It is a good replacement for the sweet starter in recipes, which use a combination of starter and bakers yeast, e.g. this Sunday braid with sweet starter.