title: Cyclone selection influences protein damage during drying in a mini spray-dryer.
abstract: The use of a small-dimensioned cyclone separator to spray-dry an aqueous solution of lysozyme on a mini spray-dryer produces consistently higher protein inactivation at all drying-air outlet temperatures examined between 50°C and 105°C. Differences in drying air flow rate through the machines will influence droplet/particle residence times within the drying chamber, but these are considered too small to explain the result. It appears more likely that a higher separation and retention of fines within the small cyclone causes higher measured protein inactivation. By virtue of their small size the fines have a greater specific surface area and suffer therefore a greater degree of protein damage when passing through the spray dryer from nozzle to collecting vessel. Although the dry powder yield is higher with the small-dimensioned cyclone than that obtained with the standard cyclone, the profile of residual moisture versus T(outlet) is irregular in shape. A possible lack of equilibrium between the attributes of the protein particles and the exhaust air needs therefore to be considered.
authors.affiliation: Division of Pharmaceutics, Friedrich-Alexander-University, Cauerstr 4, 91058 Erlangen, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bögelein
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Lee
mesh_terms: D003890:Desiccation / Q000295:instrumentation; D004867:Equipment Design; D009113:Muramidase / Q000737:chemistry*; D010316:Particle Size; D011208:Powders; D055550:Protein Stability; D013499:Surface Properties; D013678:Technology, Pharmaceutical / Q000295:instrumentation; D013696:Temperature; D013816:Thermodynamics
chemical_list: D011208:Powders; D009113:Muramidase