Identification and quantification of phosphorus in cheeses - methodological investigations by solid-state 31P NMR spectroscopy
International audience; NMR has been shown to be an interesting tool for investigating dairy foods, in particular cheese products, for which the method is non-destructive and well suited for investigating their compounds showing different structure and mobility during ripening. Solid-state magic angle spinning 31P NMR spectroscopy was used to characterize the structure and composition of semi-hard cheeses. Assignment including overlapping resonances from mobile/immobile phosphorylated serine residues and inorganic calcium phosphates, has been realised using different NMR techniques (spin echo, cross polarisation and single pulse excitation) and by comparison with spectra of literature. Stud…
Distribution and mobility of phosphates and sodium ions in cheese by solid-state 31 P and double-quantum filtered 23 Na NMR spectroscopy
The feasibility of solid-state magic angle spinning (MAS) (31)P nuclear magnetic resonance (NMR) spectroscopy and (23)Na NMR spectroscopy to investigate both phosphates and Na(+) ions distribution in semi-hard cheeses in a non-destructive way was studied. Two semi-hard cheeses of known composition were made with two different salt contents. (31)P Single-pulse excitation and cross-polarization MAS experiments allowed, for the first time, the identification and quantification of soluble and insoluble phosphates in the cheeses. The presence of a relatively 'mobile' fraction of colloidal phosphates was evidenced. The detection by (23)Na single-quantum NMR experiments of all the sodium ions in t…