Characterisation of food powder flowability

This paper presents a characterisation of the flow properties of four food powders (flour, skim-milk, tea and whey-permeate). Physical property measurements, including particle size, bulk and particle densities, water sorption isotherms and DSC thermograms, are presented. Powder flowability was measured using an annular shear cell. The flowability of the 4 food powders are compared and discussed with reference to their physical properties and the relative humidity of the surrounding atmosphere. One application of powder flowability data is in the design of hoppers. Different failure properties from shear tests are calculated for each of the food powders. They are then applied to estimating and comparing the critical hopper dimensions for mass flow for each powder. (C) 1999 Elsevier Science Ltd. All rights reserved.