This second kneading step also helps distribute the yeast cells evenly throughout the dough.
After this second kneading step, the dough is again left to rest to allow further yeast respiration.
Because the yeast cells have been distributed evenly, the CO2 produced will be distributed more
evenly throughout the dough.
This complex preparation step of kneading and fermenting thus produces a light and airy dough where
the even distribution of gases produces a more evenly risen final product after baking.
Once the dough has risen sufficiently, it is placed in a hot oven.
During the initial stages of baking (ie the first 10 minutes), the dough will expand greatly in volume –
this is known as “oven spring”. This is due to a number of contributing factors:–
· As dough temperature increases up to about 60 C, both amylase activity as well as yeast activity
increase. Increased amylase activity results in the more rapid conversion of starch to maltose,
which further increases the yeasts food supply. Increased yeast activity means that more CO2 will
be produced, further increasing the quantity of gas incorporated in the dough. When temperatures
greater than 60 °C are reached, the enzymes are deactivated and yeast cells die. The yeast stops
· As temperature increases, all the gases – ie the CO2 produced by the yeast as well as the air
introduced during kneading, expand.
· Also, some of the free water in the dough, as well as the ethanol produced by the yeast, will
evaporate, further expanding the dough.
So the first ten minutes of baking are associated with a high level of gas production and expansion.
Due to the relatively elasticity nature of the protein network in the dough, these gases will expand
without breaking the protein network. However, before cooking, several cuts are normally made on the
top surface of the dough with a knife, to further increase the ability of the dough to expand, so that it
can expand further as the gases expand, without forming unattractive cracks.