Identifying dough development peaks

When testing flour for properties like dough development time and water absorption, correct identification of the peak resistance is both critical and tricky. The doughLAB uses advanced algorithms to do this, protecting millers and bakers from costly mistakes.

While it should go without saying that accurate and reproducible test results are needed to correctly specify commodities like flour, the fact is that relatively inaccurate and subjective methods are still widely used to specify functional performance like dough mixing properties. These specifications are then used in trade to indicate the suitability and mixing requirements of flours for many different products including flat and leavened breads, noodles, pasta, pastries, cakes, cookies and more.

One important example of this is how users measure peak torque when mixing flour with water. The true development peak indicates that the flour's gluten has optimally formed a viscoelastic network and evenly bound air during the mixing process. This enables products like bread to subsequently rise, hold shape in the oven, and provide an even crumb structure in the final product. As well as knowing the right amount of water to use, the baker must also ensure the dough is neither undermixed nor overmixed to get the best performance from his or her flour.

So peak resistance is a critical dough mixing parameter to get it right. It is used to optimise the amount of water to add (Water Absorption), the amount of mechanical energy needed (Dough Development Time) and the tolerance of the dough to overmixing (Stability or Softening). These three specifications are commonly reported for flour.

But surely picking a peak is easy? Not always. In fact, the problem of picking the wrong peak has become increasingly common with stronger wheats often milled to high extraction rates which then produce multiple or indistinct peaks. Blending flour streams and adding dough improvers further impact the curve shape.

Dough mixing in conventional equipment like the doughLAB or the Farinograph® creates a relatively broad toque curve as shown below.

Dough mixing curve. The three lines represent the minimum, average and maximum mixing torques throughout the test.

In this example the absolute maximum torque was followed by a lower 'knee' in the curve that occurred at around 3 minutes into the test. Many, but not all, schools of bakers would pick the second inflexion as the true development peak. Selecting the first peak could lead the baker to seriously undermix this flour.

Where older test equipment is still in use, the dough development peak is still judged subjectively from a paper chart. Even with later electronic recording versions, operators still frequently manually adjust the peak chosen by the software's basic maximum torque selection function. The problem here of course is that there is no traceability, no objective umpire, for businesses to agree upon what is a correct specification and when an error has occurred.

Subsequently we were approached by the flour industry to see if we could improve on this and worked with them to do so. Our goal was to emulate human curve evaluation while maintaining the objectivity of computer-based evaluation.

After several iterations we finally derived a method that detected curvature rather than convexity, emulating the skilled bakers' evaluations much better than simple derivatives or inflexions could. It also became obvious during this process that not all schools of bakers agree on when to select a knee rather than an absolute peak. So we also added 'rules' to let them tune the system to conform to their local practices yet remain objective in the specification.

This function has been added to our DLW software and is available to all doughLAB users. Ultimately the value here is provision of more reliable flour specifications to the benefit of both producer and consumer.

Read more about the doughLAB.