Engineering: Recycling and the "Age" of Dough
L. Levine. Leon Levine & Associates, Albuquerque, NM. Cereal Foods World 52(6):328-329.
On a number of occasions I have observed that people do not correctly consider and/or analyze the recycling of dough and other products. For the purpose of illustration, consider a simple process that incorporates recycled dough. One of the things we are interested in understanding about this process is the "age" of the dough, meaning the number of times the average piece of dough has gone through the process. Why are we interested? In general, in processing a biological material, the material irreversibly changes every time it passes through the process. Normally, sheeting a product results in a "breakdown" of the viscoelastic structure of the dough. In the case of extrusion, every time the starchy material passes through the extruder, some dextrinization of the starch occurs, or, in the case of protein-based materials, cross-linking and reduction of solubility occurs. This column investigates how to measure the age of dough and how many cycles one has to run to achieve a steady state.