In the case of the alveograph, a dough extensibility test is carried out. For this, a piece of dough is extended into a bubble and the change in pressure within the bubble recorded. The changes in pressure describe the extensibility resistance and the extensibility of the dough.
With the help of the integrated mixing chamber system, a wheat dough is made from 250 g flour (15 % water content) and 125 ml water addition. A 0.025 % sodium chloride solution is used as the liquid addition. Following the completion of the mixing process, the dough is led out via an opening as a sheet of dough. Five round pieces are cut out of the sheet of dough and, 28 minutes after the mixing time has come to an end, are placed one after the other in the measuring device and measured.
Evaluation
The P value is the height of the curve in millimetres multiplied by 1.1 and describes the extensibility resistance of the dough. High values of extensibility resistance are a sign of very elastic doughs. Very low P values are typical for weak flours with a low stability.
The L value is the length of the curve in millimetres and describes the extensibility of the dough. Very high values are typical for plastic and unstable doughs.
The W value (deformation energy) is the mechanical work in the dough which has to be applied to blow up the dough bubble. High W values are characteristic for strong flours with a high fermentation stability.
The P/L value is the ratio between the P value and the L value and describes the ratio between the elastic (extensibility resistance) and the plastic (extensibility) properties of a dough. The P/L value and the W value should always be assessed in conjunction, as flour qualities are also found which have a high W value, but, at the same time, an unfavourable P/L ratio.
