Inimical effects of compaction speed on microorganisms in powder systems with dissimilar compaction mechanisms

Tablets were prepared from powders that were consolidated by plastic deformation and fragmentation mechanisms. Cells of Staphylococcus aureus and spores of Bacillus subtilis were incorporated in the tablets by compaction at various pressures and compression speeds. The extent of inactivation of organisms was dependent on the compression behavior of the powders, on the speed of compaction, and on the degree of densification of compacts. Scanning electron micrographs of fractured compacts revealed that particle rearrangement, fragmentation, and deformation significantly influence the "survivor". The "pressure-survivor plots" showed a linear relationship with greater inactivation in brittle material, while the extent in inactivation was reduced, and followed a nonlinear pattern in those powders exhibiting plastic deformation.