The water holding ability of powder masses: Characterization and influence on the preparation of pellets via extrusion/spheronization

Abstract

The water holding ability of powder masses greatly influences their extrusion/spheronization performance during pellets preparation. To quantify this ability and explore its influence on pellets preparation, two characterized parameters were proposed. One was the maximum water content that could be retained by the mass (WHAmax), the other was the remaining water content in the mass subjected to certain extrusion force (WHAextrusion). The methods to determine WHA were established by centrifugation. MCC, κ-carrageenan, mannitol were employed to investigate the relationship between WHA and their extrusion/spheronization performance. The results showed that the WHAmax and WHAextrusion of MCC were 1.0g/g and 0.85g/g, which were less than that of κ-carrageenan (WHAmax>6.0g/g, WHAextrusion=3.0g/g), accordingly. Since mannitol had the lowest parameter values (WHAmax=0.3g/g, WHAextrusion=0.25g/g), it was hard to be extruded. Therefore, κ-carrageenan (≥10%) or mannitol (≥30%) were added to prepare satisfactory pellets by increasing the WHA values (≥0.53g/g) of the mixed masses. In addition, the WHA of mixed masses could be predicted based on WHA of each mass. To obtain enough extrudates and non-agglomerated pellets, the water content added in the mass should be equal with WHAmax. In conclusion, the established two parameters were useful to predict the extrusion/spheronization performance of masses, therefore, selecting the potential pelletization aids and determining the optimal water content.