any types of biological ingredients are formulated into solid products by spraying the concentrate onto inactive filler cores in a fluidised bed. The desired product consists thereby of unagglomerated individual carrier particles each coated homogeneously with a layer of the active ingredient. If formulation or process conditions are incorrectly chosen, either excessive agglomeration or excessive spray drying of the feed may happen (van Ee et al., 1997). In both cases a poor product quality is achieved, and in any case, control of agglomeration is essential during scale-up.