During a protein spray drying process, thermal and mechanical stresses are exerted on the proteins leading to degradation. We hypothesize that in situ measurements of the droplet size, temperature distribution inside droplets and UV fluorescence will prov

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Protein processing and formulating often involves the removal of excess water. Spray drying is one of the most widely used unit operations for the production of stable protein containing powders. In spray drying a stock solution is atomized while subsequent evaporation increases the protein concentration within the evaporating droplets. During this drying process, thermal and mechanical stresses are exerted on the proteins that can result into degradation. Depending on the polar groups of the proteins they will accumulate at the air-water interface, forming a surface layer of proteins oriented in such a way that their hydrophilic parts are exposed to water which can cause unfolding.A fundamental understanding of the mechanisms of protein degradation is important for designing a spray drying process. The kinetics and interactions of such thermal and mechanical stresses on proteins are, however, not well understood at the single droplet level. There is no study on the time resolved kinetics of the denaturation processes at the droplet level.Experiments with single droplets are a common technique to investigate the basics of spray drying. Single droplets experiments will be conducted using a piezoelectric droplet generator in a drying chamber. The droplet size will be monitored with a camera and Mie scattering imaging. This method also gives information on the formation of aggregates and precipitation within a droplet. Temperature and protein concentration profiles will be measured with the Rainbow technique. We will use fluorescence spectroscopy with specific fluoresce dyes to monitor the unfolding and denaturation of the proteins.Our objective is a relationship between spray drying process parameters such as, droplet size, protein concentration and protein functional groups, solution additives as well as gas composition and temperature and the degradation kinetics. We hypothesize that time resolved, in situ measurements of the droplet size, temperature distribution inside droplets and protein UV fluorescence will provide degradation kinetics.