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Rapid extensigraph protocol for measuring dough viscoelasticity and mixing requirement
B. DUPUIS (1), K. Wang (1), R. Cuthbert (2), B. Fu (1) (1) Canadian Grain Commission, Winnipeg, MB, Canada; (2) Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, Swift Current, SK, Canada.

The extensigraph is particularly useful in characterizing the viscoelastic balance between dough strength and extensibility, which are directly related to the dough handling properties in the baking process. The standard method requires milling to prepare large amounts of flour and testing throughput is minimal due to the prerequisite for farinograph water absorption and long dough resting time. This limits the use of the extensigraph in the milling and baking industry, as well as for the screening of breeding populations which are usually large in sample number but very limited in sample size. Therefore, a rapid extensigraph method was developed that reduced sample size (as low as 165 g wheat) for milling, and more than tripled sample throughput by using a pin mixer for dough preparation and reducing the dough resting time. Flour (100g) prepared with a Quadrumat Junior mill was mixed with a Swanson type pin mixer to develop dough at constant water absorption of 67.5%. The dough was subsequently stretched by an extensigraph after 15 min of floor time and 30 min resting. Strong correlations were found for both R<i>max</i> (<i>r</i> > 0.93, <i>p</i> < 0.001) and extensibility (<i>r</i> > 0.64, <i>p</i> < 0.001) for the proposed rapid extensigraph method with the standard extensigraph method and a modified version currently used in the evaluation of dough properties of breeder lines in Canadian wheat registration trials. Additionally, the mixing parameters (time and energy) obtained during dough preparation provided further information about dough strength and mixing requirement. By significantly reducing sample size requirement and dramatically increasing testing throughput, this rapid extensigraph method can be widely adopted in the flour industry and meets the need for a fast evaluation of dough strength in breeding trials.