Impact of fortificants on the powder properties of a gluten-free porous starch matrix of puffed rice flour

Iron and zinc fortified pulverized expanded porous starch matrix of puffed rice (EPSMPR) flours of different particle sizes (50-150, 150-300, 300-425, 425-500, and 500-710 mu m) were analyzed for powder properties and compared with un-fortified EPSMPR flours. Both fortified and control EPSMPR flour samples showed flow stability values close to 1, signifying the integrity of the flour matrix to various flow conditions. At higher rotor speed (up to 100 mm/s), no significant increase in the compaction coefficient was observed for both fortified and control EPSMPR flour of varying particle size, indicating flow speed independency. Increase in caking strength (up to 61%), water absorption capacity (up to 16%), and swelling capacity (up to 20%) of EPSMPR flour was observed with particle size. PCA analysis revealed a negative correlation between tapped and untapped densities and water absorption index: the angle between them was approximately 180 degrees. Similarly, the angle of repose correlated negatively with the caking index.