An Investigation into the Flowability of Flours and Evaluation of testing methods of Powder Flow Tester

Abstract

Food processing industries encounter several problems regarding powder fowability, such as arching or no flow, inconsistent flow, segregation, flooding etc. due to the lack of fundamental understanding of the physical properties of the bulk solids to its flowability and the subsequent influence of the same on the selection of critical hopper parameters. In this study, the physical and flow properties of wheat and chickpea flour were studied. Flow properties were tested using powder flow tester (PFT) with standard and custom (with separate samples) test methods along with different options (geometric spacing, even spacing, doubling progression, tangent to Mohr circle). Results of instantaneous flow property tests showed that wheat flour falls in the cohesive region and chickpea flour in very cohesive region. There was no considerable effect of time consolidation on the flowability of wheat flour, whereas the flowability of chickpea flour decreased considerably to non-flowing state. A significant difference was observed between the “standard” and “custom” (with separate samples, geometric spacing and tangent to unconfined Mohr circle) instantaneous flow function test results at higher stresses for chickpea flour. The “custom” test method provided better flow function results than that of “standard” methods. The conical shape hopper was found to be more suitable for wheat flour with a hopper half angle of 32°. Wedge shaped hopper for chickpea flour with a hopper half angle of 20° was considered to be a more judicious choice.