Commercial pregelatinized starches: ability to settle and rheological evaluation.

The ability to settle and the tribological properties of three samples of pregelatinized starch widely available commercially were investigated with reference to their technological implications. In particular, we evaluated the influence of storage conditions, storage time, moisture content, equipment, handling, and mechanical treatment on the apparent volume, poured density and tapped density, as well as on tests of flow parameters such as basic flowability energy. The results obtained highlight the fact that the technologically relevant behaviour of pregelatinized starches in terms of apparent volume and tribological properties may be influenced not only by relative humidity (RH%) conditions, but also by common pharmaceutical operating practices. In particular, previous mechanical treatment can lead to statistically different behaviour in tests of ability to settle according to pharmacopoeial specifications, depending on both RH% conditioning and the amount of powder, although the materials under investigation all conform to the respective monograph in the Pharmacopoeia. All these aspects are of special interest with regard to the various pharmaceutical formulations which include pregelatinized starch, both on an industrial scale and in small-scale production.