only a single cell, which lies “asleep” until it comes into contact with warm water. Once “woken up” with
heat and water, the yeast begins to feed on any sugar it can find, releasing CO2. As it feeds on the
sugar, it is provided with energy which allows it to grow. Yeast grows by dividing its cell membrane
and all its cell contents evenly in two to form two new cells.
When preparing bread, the flour is mixed with the water, salt and yeast to form a dough. The first
process of making bread involves kneading this dough until it becomes smooth and stretchy, due to
the gluten proteins present in the flour.
The gluten proteins:
This initial kneading step helps unwind the gliadin and glutenin proteins by breaking their hydrogen
bonds and disulphide bridges, which then line up to form and develop the strong gluten network.
Some intramolecular loops that are preserved in the proteins give the dough its elasticity. The strong
and elastic dough produced is able both to trap the air bubbles without breaking due to its strength
and to allow the bubbles to expand during cooking due to their elasticity. The addition of salt helps the
protein network by using its charged ions to favour the attraction of the proteins to each other and
therefore the formation of a protein-protein network.
The other proteins:
As well as the gluten forming proteins – flour also contains other proteins that play in important role
during the kneading step. These include the enzymes, and most specifically it is the amylases have a
particularly important role in bread making. These enzymes use the water present in the dough to
attack both the amylose and amylopectic molecules located in the starch granules in the flour at
random points in their structure to break them up into molecules of maltose (a simple sugar molecule
made of two glucose molecules chemically joined together). These molecules will later be used by the
yeast to respire, during a process called fermentation. It is for this reason that flour should always be
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