Surface composition and microstructure of spray-dried microparticles: A review about their effect on functional properties

Many functional properties of spray-dried microparticles are affected by the presence and composition of the materials used in the matrix and on the surface. The characteristics of these materials are an essential factor because any damage or alteration on the microparticle surface can affect the protection and retention of the bioactive-loaded delivery system and influence its interaction with the environment. There is a real gap between scientific concerns from the field and accessible reviews on the subject. This review presents a detailed description of the surface modification of spray-dried powders for improving the powder quality, efficiency of the microencapsulation, and microencapsulation process design in food industries. Additionally, the theoretical foundation, mechanisms, and methods used to understand the surface modification of spray-dried food powders are highlighted. Therefore, for a better understanding of the mechanisms involved in the particle surface formation, the application of advanced microscopy techniques and x-ray photoelectron spectroscopy (XPS) used together have offered very precise and detailed results under different conditions at the molecular level. These findings will contribute to further research improvement about the surface composition of spray-dried microparticles and how they influence on their functional properties.