Drying is a powerful process for the dairy industry in conceiving innovative products with longer shelf life, that are adapted to the varied customer demands and easier to store and transport. Nowadays, dairy powders, and notably infant milk formulas (IMFs), represent an increasing share of the global market due to several economic and social factors, such as globalization and population growth. However, the drying of dairy products has still considerable limitations despite this growing interest, mainly related to the lack of knowledge concerning the physics of the phenomena taking place in industrial facilities. In particular, a full understanding of the mechanisms leading to the interfacial sol–gel transition in droplets of dairy mixes is far from being achieved. To address this scientific shortcoming, two main approaches have been adopted, i.e. the design of innovative model spray dryers, and investigation at the laboratory scale combining different techniques for the study of suspensions/emulsions. These strategies have allowed exploring of the paradigm linking the physico-chemical properties of milk components to the development of the drying-induced droplet skin that affects the final functional powder properties, as highlighted in this chapter.