An investigation on the dissolution qualities of foam granulated products

The worldwide home care industry makes widespread use of granulated laundry powders which must be highly soluble and dissolve rapidly to induce an effective wash cycle. The morphology of these powders influences their dissolution rate. Binder addition methods affect the properties of granulated products. Foam granulation is a method of granulation where a foamed binder is used. This may provide added advantages like: increasing wetted area per liquid mass, reducing saturation, and enhancing dissolution rate through enhanced granule structures or narrower particle size distribution. Here, three separate binder addition methods (spray addition, drop addition and foam addition) were trialled using a lactose and microcrystalline cellulose (MCC) based formulation to assess the effect of foam granulation on size, granule structure, and dissolution behaviour. Foam granulation produced smaller granules at the same liquid level, with a different morphology. However, the dissolution kinetics of the foam granules appeared unaffected by foam. Dissolution tests showed that under stagnant conditions, there was no significant difference between dissolution rate or extent between droplet-fed and foam granulation, though spray granulation achieves a much slower dissolution rate than either process. Foam granulation has been proposed to be dependent on formulation properties and further investigation of alternative formulations with different wetting behaviours is required to confirm the effects of foam granulation on structure.