Studying the influence of milk processing on two relaxation components of aged cheeses through benchtop FFC-NMR analysis

Hard PDO (Protected designation of origin) cheeses such as Parmigiano Reggiano or Fiore Sardo are traditionally made with raw milk, as this allows them to develop their characteristic texture, taste, and smell. Guidelines for the Fiore Sardo production mandate that it should be made from raw milk, but industrial products have been long suspected of being produced using pasteurized or thermized milk. Concerning quality control of the non-bovine milk dairy products, there is no official, reliable, and fast method to differentiate between raw milk and pasteurized milk cheeses. In this work, we present benchtop Fast Field Cycling-Nuclear Magnetic Resonance (FFC-NMR) relaxometry as a possible method for such discrimination. Beyond being the yes or no technique, it allows a deep characterization of the molecular dynamic of cheese components, describing the state of the water, fat, and protein matrix. In this work, we demonstrate that using a new FFC-NMR approach, the protons within Fiore Sardo cheeses can be grouped into two populations, characterized by short and long NMR relaxation times, respectively. With this result, we demonstrate that the artisanal and industrial cheeses can be uniquely identified and that the component with short relaxation time is a good indicator to discriminate them. As far as we know, this innovative approach has never been used to study food products.