hydrogen and disulfide bonds) that usually hold individual proteins together to break, and the proteins
will unwind, although some of their intra-molecular loops may be preserved in the unwound protein.
These unwound proteins line up as the dough is kneaded further and will tend to line up in roughly the
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same direction. Once they have all lined up, new hydrogen bonds and disulphide bridges are formed
between neighbouring proteins, and a protein network is formed. Once the bonds have formed, the
proteins will tend to stay in these positions, and the dough becomes rigid and harder to handle. This
gives it its strength. However, the intra-molecular loops that have been preserved in the structures of
the unwound proteins will act as springs to ensure elasticity.
Overkneading: Overkneading can destroy the texture of dough. Over-kneading can break up both the
disulphide bonds in the intra-molecular loops, reducing elasticity, and the disulphide bonds holding the
network together, reducing strength.
However, it is very difficult to over-knead by hand.
Flour age: Dough consistence may also be affected by the age of the flour. In new flour, the sulphur
atoms involved in forming disulphide bridges may be attached to groups known as “thiol groups”.
These thiol groups defavour the formation of these disulphide bridges (both in the protein network and
the inter-molecular loops). Therefore, both the strength and elasticity of the dough will be reduced. As
flour ages, these thiol groups oxidise, and are no longer able to prevent disulphide bond formation, so
disulphide bonds form both in the protein network and within protein loops, producing a stronger and
more elastic dough.
Types of flour: Some flours contain a higher protein content than others. These flours tend to be used
for used for making pasta and bread, where the high protein content is required. These flours are
usually extracted from what are known as “hard wheats”, such as durum wheats. Flour extracted from
“softer” grains will have higher starch content, but a lower protein content, so are used more often for