Proteomic Characterisation and Digestibility Score of Milk Powders Obtained Through Pulse Spray Drying and Traditional Spray Drying

Powdered milk is a food ingredient valued for its long-term shelf life and space-saving qualities. However, the process of concentrating and drying milk, usually through spray drying, can lead to chemical modifications in proteins. This study aims to evaluate how two drying technologies, spray drying (SD) and pulse spray drying (PSD), affect protein modifications in skim milk powders (SMP). Batches of SMP were produced using both SD and PSD technologies, with drying outlet temperatures set at 70 °C and 100 °C. Electrophoresis, chromatography, and mass spectrometry were exploited to assess protein modifications induced by the drying processes. In vitro digestion models were applied to evaluate the digestibility scores of the SMP. The treatment temperature was the major factor for protein modifications in both PSD and SD processes, as evidenced by electrophoresis and chromatography analysis. As indicated by chromatography, PSD technology resulted in lower whey protein modifications compared to SD. Interestingly, the digestibility scores were higher than 95 and no significant differences were observed between the two technologies. In conclusion, proteomic methods effectively identified and semi-quantified thermal-induced modifications in SMP produced using an alternative drying technology as compared to the conventional SD. PSD is a convenient powdering process that preserves protein quality and functionality.