[Sca-cooks] bread chemistry article

Tue May 22 12:43:23 PDT 2001

   CAUSE OF DOUGH FORMATION DISCOVERED
    A Kansas State University scientist has solved a problem that has
confounded the baking industry for more than 50 years: when mixing flour and
water, what chemical reaction causes the elastic bread dough to form?
Katherine A. Tilley, a cereal chemist, shows experimentally that within the
wheat flour protein called gluten, tyrosine molecules react with other
tyrosine molecules either on the same protein chain or across separate
protein chains. This build up of a complex network of strong tyrosine
cross-links become the scaffolding of dough. Tilley's research, appearing in
the June print issue of the journal of the American Chemical Society, is
within the world of wheat, flour and baked goods an insight similar to that
of the basic structure of DNA. Gluten is the protein component of wheat
flour and it's what gives bread dough its viscous and elastic properties
when mixed and kneaded. Tyrosine is an amino acid or "building block" of
gluten protein structure. "The baking industry has thought for more than
half a century that dough forms because disulphide bonds are breaking and
reforming, breaking and reforming, but no scientist had ever actually shown
this to be the case," says Brendan Donnelly, head of Kansas State's
department of grain science. "Being able to measure and monitor tyrosine
cross-linking formation will be a tremendous saving to the baking industry
because it offers the potential ability to control the uniformity of flour
quality."