On Food and Cooking

Starters A general method for incorporating
yeast into bread dough that maximizes the
effective fermentation time and flavor
production is the use of pre-ferments or
starters, portions of already fermenting dough
or batter that are added to the new mass of
flour and water. The starter may be a piece of
dough saved from the previous batch, or a
stiff dough or runny batter made up with a
small amount of fresh yeast and allowed to
ferment for some hours, or a culture of “wild”
yeasts and bacteria obtained without any
commercial yeast at all. This last is called a
“sourdough” starter because it includes large
numbers of acid-forming bacteria. Starters go
by many names — French poolish, Italian
biga, Belgian desem, English sponge — and
develop different qualities that depend on
ingredient proportions, fermentation times
and temperatures, and other details of their
making. Sourdough breads are described on p.
544.