Microstructural characterization of dairy products: structure–function relationships, processing effects, and industrial significance

Microstructure is a fundamental determinant of the quality, functionality, and stability of dairy products, governing critical attributes such as texture, rheology, meltability, and shelf-life. Conventional compositional analyses are not sufficient to fully explain processing-induced changes and product defects, necessitating microscopic approaches. This review examines the role of microstructural analysis as a quality assessment and process optimization tool for several dairy products, including fluid milk, fermented products, cheese, ice cream, butter, traditional dairy products, and milk powders. Emphasis is placed on the application of complementary microscopy techniques, light microscopy, confocal laser scanning microscopy, scanning and transmission electron microscopy, and cryogenic imaging methods, to elucidate the spatial organization and interactions of casein networks, fat globules, aqueous phases, air cells, and crystalline components. The review discusses evidence linking microstructural features with macroscopic product properties, demonstrating influence of processing variables such as homogenization, heat treatment, fermentation, freezing, and ripening on the changes in structural organization and, consequently, product characteristics. Furthermore, it illustrate the utility of microscopy in defect and critical control point identification, and industrial troubleshooting, including syneresis in yoghurt, textural defects in cheese, recrystallization in ice cream, and poor rehydration of milk powders and establishes microscopy as an indispensable tool for dairy product design, and quality control, providing considerable potential for enhancing consistency, functionality, and processing efficiency for dairy industry.