Protein aggregation mechanism in UHT milk: supramolecular evidences

The protein aggregation mechanism in UHT milk samples stored at ambient temperature for 1, 3 and 5 months was assessed in this study. Three phases of the UHT milks were studied: supernatants, dispersed phase and sediments. The supernatants showed a great variability, suggesting the presence of a dynamic arrangement within the protein system of UHT milk, which moves towards the formation of the sediment. The application of 2D-electrophoresis (AU-PAGE-SDS-PAGE) and mass spectrometry analyses were carried out to study the main heat-induced supramolecular protein aggregates. These aggregates were found mainly in the supernatant and their composition changed along the storage, as a consequence of the medium chemical changes, which are temperature- and pH-depended, whereas the composition of the dispersed phase and sediment denoted a hierarchical mechanism of assembling.