French Baguette with poolish

What is Poolish (Biga)?

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.

Biga and poolish are terms used in Italian and French baking, respectively, for sponges made with domestic baker's yeast. Poolish is a fairly wet sponge (typically made with a one-part-flour-to-one-part-water ratio by weight), while biga is usually drier. Bigas can be held longer at their peak than wetter sponges, while poolish is one known technique to increase dough's extensibility.

Poolish
Poolish was one of the first pre-ferments elaborated with commercial yeast. Polish bakers, where the name originated, are credited with inventing this pre-ferment in Poland at the end of the 19th century. The process was then adapted in Austria and later in France. Bread made with a poolish was lighter and less acidic than the sourdough bread commonly baked during that time, and it started to gain poularity. With the availability of commercial yeast, more bakers began using the poolish process, and the sourdough process declined. Technically, we could classify the poolish as a transitional pre-ferment between baking using sourdough and baking with commercial yeast using a straight process. Even in Paris today, some windows of older bakeries display two signs. One reads "pain Viennois" -bread from Vienna (made with commercial yeast), and the other reads "pain Francais" -bread from France (made with sourdough).
Traditionally, the size of the poolish is calculated based on the water involved in the total formula. Use from 20% to 80% of the water to prepare the poolish. Then, elaborate the poolish using the same amount of flour as water ( this 100% hydration, provides a liquid consistency); no salt is usually incorporated in the poolish. It is important to note that the poolish is allowed to ferment at room temperature. Therefore, the quantity of yeast is calculated depending on the fermentation time of the poolish. Although it is difficult to give precise numbers, the recipe below provides some guidelines to calculate the quantity of yeast to use in the poolish.

Baguette with poolish (biga)

Poolish:

1 Kg white bread flour
10 g wet (fresh compressed) yeast
1 Lt water
Method:
Mix all ingredients together, transfer into a container, cover and leave at room temperature overnight.
P.S. if you are living in an area where the ambient temperature is hot, leave in fridge overnight.

Dough:

1.2 kg white bread flour
50 g salt
80 g wet yeast
Method:
Put the dough ingredients and the poolish together and mix on slow speed for 2 minutes and fast speed for 6 minutes with a dough hook.
Rest dough for 20 minutes before scaling at 400g each.
Rest another 10 minutes. Shape into long thin cigars and place on baking tray.
Cover with plastic and rest for 45 minutes to rise.
Remove plastic. Spray the dough with water ( use a spray gun), and bake at 240 degrees C, for 10 minutes.
Reduce heat to 210 degrees C and bake for another 15 minutes.
Cool on rack, (if you can wait that long)!