Modern mass spectrometric methodologies in monitoring milk quality

Structural modifications induced by industrial treatments on milk proteins have been investigated using a new analytical protocol based on mass spectr ometric procedures (electrospray and matrix assisted laser desorption ioniz ation mass spectrometry) providing a direct correlation between the severit y of the treatment and the damages observed. The application of this proced ure to the analysis of whey proteins from milli samples submitted to differ ent thermal processes cofirmed that under these conditions protein modifica tion is essentially due to the nonenzymatic glycation of amino groups by la ctose (Maillard reaction). A detailed structural investigation of the modif ication sites, carried out by the mass mapping strategy, revealed the occur rence of preferentially lactosylated sites in both alpha-lactalbumin and be ta-lactoglobulin.