Advancement of milk protein analysis: From determination of total proteins to their identification and quantification by proteomic approaches

Milk proteins are important components that confer several nutritional and functional properties to milk and dairy products. As these proteins have complex nature and wide variability, their analysis is not trivial and requires several methods to be used individually or in combination. In this article, we provide a comprehensive review of conventional and more advanced methods used in the analysis of milk protein content, composition, and structural properties. Different traditional methods (mainly titration and spectrophotometric) are still used for the determination of total protein content, while chromatographic and electrophoretic techniques, enzymelinked immunosorbent assays, and infra-red spectroscopy are used to separate, identify, and quantify individual proteins. For advanced structural identification of separated proteins, nuclear magnetic resonance, X-ray diffraction, and mass spectroscopic techniques can be used. Of these methods, the analyst may select those relevant to different applications in milk and dairy products research.