Rheological Characterization of Cereal Products

May 20/Journal of Technology & Science -- "In the manufacture of cereal products, such as milling of wheat, the mixing of the dough, and baking of cakes and breads, because direct end-product testing is expensive and time consuming, it is popular for industry to utilize appropriate surrogates (representative indirect measurements) to predict various end-product outcomes. For some specific properties, such as milling yield, dough viscoelasticity, or bread loaf volume, the identification and validation of possible surrogates is a major motivating goal in the R&D of cereal science," scientists in Canberra, Australia, explain in a new report.

"For example, because end-product quality of many foods made from wheat flour is known to depend principally on the structural and rheological properties of the high-molecular weight protein fraction in the flour, the rheology of doughs made from wheat flours is an appropriate and popular choice for the surrogate. Equally important is the end-product testing of the flour milled from a wheat. In this situation, an appropriate surrogate is some measure of the rheology of grain hardness; namely, the deformation and fracturing of the wheat during the milling as a function of the mechanical properties of the various botanical layers within wheat kernels. The current popular measures are particle size index and single kernel characterization system (SKCS) hardness index. However, they are quite indirect and only single-value summaries of the mechanical strengths of the botanical layers.

"An alternative strategy is the measurement (on an SKCS 4100 device) of a large number of individual crush response profiles which are averaged to produce a representative average crush response profile (aCRP), which can be viewed as an indirect measurement of the strengths of the internal botanical layers.

"To utilize the rheology of grain hardness as a predictor for the flour that can be milled from various wheats, there is a need to first characterize the information that can be recovered about the mechanical strengths of the internal botanical layers from the morphology of an aCRP. This is the goal and focus of this article. From this perspective, the SKCS 4100 device can be viewed as playing the role of a grain hardness rheometer. Independent motivation identifying a need for an explicit characterization of the rheology of grain hardness is the increasing list of publications exploring and exploiting various features of aCRPs as predictor of key aspects of end-product quality. The results of such publications are briefly reviewed to highlight the growing importance of grain hardness rheology in cereal science. In addition, illustrative examples arising from the current deliberations are included," wrote R.S. Anderssen and colleagues, Australian National University.

The researchers concluded, "The SKCS rheological characterization of the strengths of the botanical layers in wheat kernels, as explained in this article, will apply more generally to all cereal grains."

Anderssen and colleagues published their study in European Food Research and Technology ("Characterizing and Exploiting the Rheology of Wheat Hardness." European Food Research and Technology, 2009;229(1):159-174).

From the May 26, 2009, Prepared Foods E-dition