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  • Author or Editor: C. Wrigley x
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In Australia in the early 1890s, the wheat breeder William Farrer and chemist Frederick Guthrie shared a vision of selecting cross-bred wheats for enhanced grain quality. Guthrie was the newly appointed chemist of the Department of Agriculture of the Colony of New South Wales. Their goal to select lines with good milling quality was difficult because Farrer’s plots produced only ounces of grain for testing. In a day when there was no written background to the task, Guthrie set about devising small-scale milling equipment that could produce flour from the many small samples of grain coming from Farrer’s breeding program. Guthrie used two pairs of small rolls manufactured by the Ganz Company of Budapest. The testing procedure was extremely tedious, requiring 13 successive passes of milling and sieving. Guthrie’s test mill and the results have been described in several publications. In addition, his mill has been reconstructed as a one-quarter-scale model as a result of the efforts of Mr Colin Hopkins, a retired chemical engineer. In contrast to this 120-year-old technology, there is now more advanced technology for test milling very small grain samples (only 5 to 10 grams of grain) with the development of a novel laboratory micro-mill, the FQC-2000, manufactured by Inter-Labor, Hungary. These old and new developments have involved collaborations between Hungary and Australia.

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Two fundamental test systems were used to evaluate the visco-elastic properties of doughs from wheat samples of three varieties grown at four distinct sites. For comparison, tests were also performed with traditional equipment, namely the Mixograph, an extension tester and a Farinograph-type small-scale recording mixer. Uniaxial dough elongation (with an Instron) produced results similar to the conventional extension tester, except that results were provided in fundamental units (Pascals), the critical value recorded being the elongational stress at maximum strain. Stress relaxation measurements were performed following a small initial shear strain. With this method, it was possible to distinguish between the viscosity and the elastic components of dough visco-elasticity. In all the tests the extra dough-strength properties were evident for the variety (Guardian) that had the 5 + 10 glutenin subunits, in contrast to the other two with the 2 + 12 combination of subunits.

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