extensograf

Extensograf, also known as extensograph, is a laboratory instrument used to characterize the rheological properties of dough by measuring its resistance to extension and its extensibility. It is commonly employed in flour quality assessment and bread making to relate dough behavior to loaf characteristics such as volume and crumb structure.

The principle of the device involves placing a standardized dough sample between two clamps or rollers and extending it at a controlled rate while recording the resistance over time. The test simulates the stretching and gas expansion that dough experiences during fermentation and baking, producing a curve that reflects how the gluten network holds and yields under stress.

A typical test yields several key parameters. Resistance to extension is reported as R (often interpreted as the dough’s strength or firmness at a given time). Extensibility, E, indicates how far the dough can be stretched before rupture. The area under the curve corresponds to the energy required to extend the dough. The shape of the curve and the R/E values together provide information about dough handling, strength, and potential tolerance to processing.

Applications of Extensograf testing include quality control in flour mills, formulation optimization for bakeries, and research on dough formulations or additives. It aids in predicting loaf volume, crumb texture, and overall bake performance, helping producers select flours and adjust hydration, mixing, and fermentation parameters.

Historically, the instrument was popularized by Brabender and remains a standard tool in many rheology laboratories. Today, digital variants and standardized protocols continue to support its use alongside related devices such as farinographs and mixographs.