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Small scale dough testing as a research tool to investigate structure/function relationships. F. BÉKÉS
(1) and P. Gras (1). (1) CSIRO Plant Industry, North Ryde, NSW, Australia.
A unique feature of wheat flour is that when it is mixed with water it
forms dough, a material with complex rheological properties. The viscoelastic properties and gas holding
capacity of wheat flour dough is the basis for the production of a wide range of products (bread, noodles,
pasta, etc.), among some of the most important classes of food around the world. An important objective of
the research presented is to define the role of the chemical constituents of wheat flour in determining the
functional properties of dough and applying this knowledge to establishing quality trait targets for
improving wheat cultivars through breeding. In addition, the research provides a basis for monitoring
manufacturing technologies and target end-product quality more economically. Both of these areas rely on
an accurate description of the phenotype (processing quality) of a sample of grain. The technology to deal
with this issue includes newly developed small-scale dough-testing equipment and protocols to determine
the mixing, stretching and end-product (baking and noodle-making) properties of as little as two grams of
flour. Small-scale testing equipment (micro-mill, 2 g-Mixograph, z-arm micro-mixer,
micro-extension-tester, 2 g-baking, and 10 g-noodle-making machines) are used to develop methodologies for early selection
for quality attributes and to investigate the structure/function relationships of flour components. The
complexity of gluten composition complicates the task of in vivo investigation of the role of
individual flour components. This problem is largely solved by the introduction of in vitro methods
using model systems to study these structure-function relationships, thus to predict the results of in
vivo experiments. Products of genetically modified genes are produced by bacterial expression and the
effects of these proteins on quality attributes are investigated using in vitro chemical and small-scale
dough-testing methodology. The results of these in vitro tests serve to select genes of interest for
quality-improvement-related wheat transformation.
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