Engineering: On the Compaction of Particulate Materials, Like Granola, Etc.
L. Levine. Leon Levine & Associates, Albuquerque, NM, U.S.A. Cereal Foods World 56(4):177-178.
In this column, Levine discusses the similarities and differences between rolling granola bars and rolling dough. The question is, “What kind of forces do particulate materials, like granola, experience as they are compressed by the process?” These forces result in the compaction and shearing of the material but also may result in breakage of friable components and in an altered texture or smearing of softer components. This is not a problem of fluid flow, but rather a problem related to the physics of moving and transferring a particulate mixture. To solve the problem, we must use principles related to the actions of friction and pressure on the motion of solids. Unfortunately, no information is available on the constants in the “angle of wall friction.” However, we can obtain a qualitative idea of how the equipment works by using “guesses” for some of the unknown constants and looking at relative effects.