(58f) A Surface Characterization Platform Approach to Study Food Powder Flowability

The surface properties of powders used in beverages have been investigated using IGC (Inverse Gas Chromatography) to assess surface energy/interactions and X-Ray Photoelectron Spectroscopy (XPS) to assess chemical 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. Five coffee powder samples, generated by three different processes (spray-drying, freeze-drying and milling) and three cocoa powders were used for this study. The data show that for both types of powders – coffee and cocoa, differences in chemical composition at the surface are detectable by XPS. The results suggest that flow is inhibited in powders with higher levels of fat deposited at the surface. The results also indicate that while powder flow is influenced by physical attributes such as particle size distribution, which influence the flowability of powders, 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 use of vapor sorption techniques, such as IGC and water sorption, in combination with surface structural characterization analytical tools (XPS) to optimize process and product development.