A pre-ferment is a fermentation starter used in bread making, and is referred to as an indirect method. It may also be called mother dough.
A pre-ferment and a longer fermentation in the bread-making process have several benefits: there is more time for yeast, enzyme and, if sourdough, bacterial actions on the starch and proteins in the dough; this in turn improves the keeping time of the baked bread, and it creates greater complexities of flavor. Though pre-ferments have declined in popularity as direct additions of yeast in bread recipes have streamlined the process on a commercial level, pre-ferments of various forms are widely used in artisanal bread recipes and formulas.
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... A pre-ferment is easy to make and usually consists of a simple mixture of wheat flour, water, and a leavening agent (typically yeast) ... the amounts of each ingredient, and when they are added, depend on pre-ferment and final-dough formulas ... is 100% hydration, and results in a relatively fluid pre-ferment ...