Identification of protein markers for the occurrence of defrosted material in milk through a MALDI-TOF-MS profiling approach.

A progressive diffusion of Mozzarella cheese products realized with frozen curd or frozen milk have been observed in the last years. In order to reveal adulterations in raw milk used for cheese manufacturing, we have developed a robust and rapid MALDI-TOF-MS profiling procedure of fresh and frozen buffalo milks. We finally identified 28 polypeptide markers of milk freezing storage.Abundance changes of polipeptide species following freezing treatment were confirmed by an independent approach. We observed the progressive formation in frozen buffalo milk of GLYCAM1-derived phosphopeptides. In addition to these species, ?-casein-derived phosphopeptides (1-68), ?-casein-derived ?2-, ?3- and ?4-fragments, ?-lactalbumin and ?-lactoglobulin showed the highest significant abundance changes in frozen milk in comparison with fresh milk.