Computer model cereal processing.

Dough processing is moving to a new era of automation. It's necessary to maintain dough mechanical properties within narrow ranges for proper control. Dough processing operations, such as mixing, transport and metering, place stresses and deformations of different types and magnitudes on the material.

These unit operations apply mechanical energy to the dough, contributing to its development. They have a large influence on its rheological properties and the quality of the final product. Thus, in order to solve engineering problems associated with dough processing, researchers should have an understanding and a quantitative description of how dough rheological properties change because of the way it is processed. There is a need to track dough deformation and stress as dough travels through various processing equipment--augers, dough developers, metering pumps, forming dies and the like.

Dough is a viscoelastic material with properties that depend on the ingredients used for its manufacture, notably flour and water, and operating conditions, such as temperature, mixing and shear. Considerable efforts have been made to understand dough rheological properties, and how they are related to the flour and ingredients used in its manufacture. Researchers have tried to improve their knowledge of processing conditions and the properties of the final product.

Most of the research, however, has been conducted using laboratory-scale equipment and has focused on characterizing dough systems, rather than on their interaction with processing equipment and processes. This approach, however, has several drawbacks and could lead to very lengthy and expensive research with little chance of success in the short term.

Computer simulation and modeling is an alternative that could be used for understanding, describing and analyzing dough processing. It has already been used in other industries and has led to significant savings in research and manufacturing costs by making it possible to test the performance of a product or process without the construction of a prototype.

The ability to model a food process involving rheologically complex materials is still at an early stage, and application of rheological data collected on dough has not found widespread utility in the development and design of equipment. Scientists at Purdue University (Whistler Center for Carbohydrate Research, Department of Food Science, 1160 Food Science Building, West Lafayette, IN 47907) are characterizing the geometry of major equipment involved in the dough processing operation: the auger, dough developer, metering pumps, manifold and forming die. They're incorporating rheological models that describe the behavior of dough. A liquid model is being used.

Models, including those covering viscoelastic effects, will be tested. Researchers intend to determine strain and stress profiles of the current process and other potential processes involving more complex geometries, notably extrusion.

Further information. O.H. Campanella; phone: [phone]; fax: [phone]; email: [e-mail].