The Effect of Operating and Formulation Variables on the Morphology of Spray-Dried Protein Particles

Abstract

The purpose of this research was to investigate the shape and morphology of various spray-dried protein powders as a function of spray-drying conditions and protein formulations. A benchtop spray dryer was used to spray dry three model proteins in formulation with a sugar or a surfactant. Physical characterizations of the powder included morphology (scanning electron microscopy), particle size, residual moisture, and X-ray powder diffraction analyses. A significant change in particle shape from irregular (e.g., "donut") to spherical was observed as the outlet temperature of the dryer was decreased. The drying air outlet temperature was shown to depend on various operating parameters and was found to correlate with the drying rate of atomized droplets in the drying chamber. The morphology of spray-dried protein particles was also affected by formulation. In protein:sugar formulations, spray-dried particles exhibited a smooth surface regardless of the protein-to-lactose ratio, whereas roughness was observed when mannitol was present at > 30% of total solids, due to recrystallization. Protein particles containing trehalose at concentrations > 50% were highly agglomerated. The presence of surfactant resulted in noticeably smoother, more spherical particles. The shape and the morphology of spray-dried powders are affected by spray drying conditions and protein formulation. This study provides information useful for development of dry proteins for fine powder (e.g., aerosol) applications.

Statistical Modeling of protein spray drying at the lab scale

“…Specifically, the outlet temperature increased with increasing inlet temperature and decreased with increasing liquid feed rate and atomizing nitrogen flow rate. These trends are consistent with the findings of others [10]. The model was reasonably accurate in predicting the experimental data ( Figure 3) with an R 2 = 0.86.…”

“…Also, when the atomizing nitrogen flow rate is high, the drop exiting the nozzle tends to be smaller, so the resulting dried particle will be smaller. These trends are expected on the basis of established spray-drying theory [1,10].…”

Dry Powders for Pulmonary Delivery of Peptides and Proteins

“…The inlet temperature is usually several tens of degrees higher than the outlet temperature. Determining the temperature variation within a drying chamber revealed that the temperature at 5 cm below the nozzle was much closer to the outlet temperature than the inlet temperature, and that the temperature at 17 cm below the nozzle, midway between the nozzle and outlet, was approximately the same as the outlet temperature (43). This means that during spray drying, droplets in the drying chamber were exposed to the temperature swayed by the outlet temperature.…”

“…The independent variables of spray drying processes are liquid feed rate, atomizing air flow rate, drying air f low rate, and inlet air temperature. Outlet temperature linearly depends on each of these variables (43), suggesting that it can be estimated if the regression lines between outlet temperature and the independent variables are available for a spray drier. The inlet temperature is usually several tens of degrees higher than the outlet temperature.…”

Encapsulation of Red Ginger Oleoresin (Zingiber Officinale Var Rubrum) With Chitosan as Wall Material

“…At the inlet temperatures were 180 °C and 190 °C have produced microcapsules rough surface and wrinkled. This happens because, at low temperatures, the drying rate would decrease so that the solidification process of microcapsules would take longer [44,45]. Wrinkles microcapsules could be caused by the diffusion of oleoresin from the microcapsules because of slow drying rate.…”