extensograph

Extensograph is a rheological instrument used to measure the resistance of dough to extension and its extensibility under standardized conditions. It was developed as part of the Brabender Instruments line in Germany in the mid-20th century and has become a conventional tool in cereal science, flour milling, and baking industry laboratories. The Extensograph provides insights into gluten strength and dough handling properties, aiding flour characterization and bread quality prediction.

In a typical test, a dough sample is prepared at specified hydration and allowed to rest and relax for a defined period. The dough strip is then placed between two clamps and stretched under a controlled mechanism, either by a constant rate of extension or by applying prescribed weights. A force-measuring device records the resistance required as the dough is extended, and a recorder traces a curve over time. The resulting data reflect both the dough’s resistance to deformation (strength) and its ability to extend without breaking (extensibility).

Key outputs from an Extensograph include measurements such as resistance to extension (R), extensibility (E), and often their ratio or related derived indices, along with the area under the curve in some protocols. Higher R indicates a stronger dough, higher E indicates more extensibility, and the R/E relationship helps characterize dough behavior during fermentation and baking.

Applications include evaluating flour quality, comparing bread-making performance of different wheat varieties, guiding formulation and hydration adjustments, and quality control in bakeries. Results are influenced by dough preparation, temperature, and aging, so standardized procedures are essential for meaningful comparisons.