Characterization of Agglomeration Process as a Function of Moisture Content Using a Model Food Powder

A model food‐powder system using rice flour of different moisture contents (11 to 22%) was used to study rheological behavior by employing a powder rheometer to obtain maximum force, energy for compression and decompression. The latter parameters were sensitive at moisture contents of ≥ 18%. The compacted mass, obtained using a rotary punch‐tableting machine, was subjected to compression testing to determine the maximum force and firmness of the compressed tablets. These two parameters increased markedly above the 17% moisture content. A significant ( P ≤ 0.01) relationship between energy for compression for powder and firmness of compacted mass indicated that an adequate integrity of the product could be achieved when a powder requires high energy for compression but low energy for decompression. A modified version of the Hausner ratio, often used to characterize the extent of compactness, was proposed that included a correction factor for loss of moisture during compaction.