Powder Technology, Vol.357, 269-280, 2019
A surface characterization platform approach to study Flowability of food powders
The surface properties of powders used in beverages have been investigated using IGC (Inverse Gas Chromatography) to assess surface energy and interactions, and X-Ray Photoelectron Spectroscopy (XPS) to evaluate elemental surface composition. The influence of surface properties on powder flowability was studied. The physical attributes of the powders were also determined in the study, and flow properties were determined using a powder rheometer and a rotating drum with image analysis. Five coffee powder samples, generated by three different processes (spray-drying, freeze-drying and milling) and three cocoa beverage powders (agglomerated and simple mixed) were used for this study. The data showed that the differences observed at the surface are detectable by both techniques, IGC and XPS. The results suggest that flow may be inhibited in powders with higher levels of hydrophobic functional groups exposed at the surface. The results also indicate that while powder flow is influenced by physical attributes such as particle size distribution, a major factor is that of the chemical composition at the surface, which in turn has a direct effect on interparticle cohesiveness. We present an assessment platform, geared toward understanding bulk powder behavior, based on the surface techniques, from a thermodynamic (IGC), spectroscopy/structural (XPS) and visualization (SEM) approaches to optimize process and product development. (C) 2019 Published by Elsevier B.V.