Physical and flow properties of pseudocereal-based protein-rich ingredient powders

Knowledge of bulk handling properties of food powders is essential in the design of industrial equipment and selection of appropriate powder handling operations. The objectives of this study were to determine the physical and flow properties of plant-based regular and protein-rich flours to establish relationships between powder physical and bulk handling properties as influenced by protein enrichment. A number of physical properties (bulk density, flowability, wall friction and compressibility) were assessed for 11 regular- and protein-rich flours from pseudocereals (amaranth, buckwheat, quinoa) and cereals (rice and maize). Relevant physicochemical properties such as particle size distribution, microstructure and water sorption behaviour were also studied. The protein-rich pseudocereal flours had irregular-shaped, rough surfaces with mean particle diameters ranging from 96.5 to 215 mm. The compressibility indices (42.6-51.4%) were higher for the former compared to the regular protein content powders and they displayed lesser tendency to uptake water with increasing relative humidity. Analysis of the flow behaviour showed the protein-rich flours to be more cohesive with higher wall friction angle values than the regular protein content powders. The new information obtained in this study is critical in optimising the processing, stability and applications of these value-added high-protein pseudocereal ingredient powders.