title: Effects of casein and fat content on water self-diffusion coefficients in casein systems: a pulsed field gradient nuclear magnetic resonance study.
abstract: The water self-diffusion coefficients in casein matrixes were measured using a pulsed field gradient spin-echo nuclear magnetic resonance technique (PFG-SE NMR). The dependence of the water self-diffusion coefficient on the casein concentration and the aqueous phase composition is reported in both a rehydrated native phosphocaseinate dispersion and a concentrated casein retentate. A model has been proposed to explain the different behavior of the water self-diffusion coefficient in the two casein systems. This model demonstrates that the water self-diffusion cannot be simply explained by the water content only. So, taking into account the specific effect of each constituent of the aqueous dispersing phase, the water self-diffusion reduction induced by the casein micelle can be modeled. The effect of fat on the water self-diffusion coefficients was investigated. Anhydrous milk fat-reconstituted retentate samples were used in order to estimate the obstruction effect of fat globules in the modeling process. The dependence of the self-diffusion coefficient of water on the fat and casein content is reported. A general model included the effect of the aqueous phase composition, and the obstruction effects of casein micelles and fat globules were proposed. This model was validated for water self-diffusion coefficients in industrial fatty retentates.
authors.affiliation: CEMAGREF, UR Technologie des Equipements Agro-alimentaires, CS 64426, 17 Avenue de Cucillé, 35044 Rennes, France.
authors.forename: Angélique
authors.initials: A
authors.lastname: Métais
authors.forename: Mireille
authors.initials: M
authors.lastname: Cambert
authors.forename: Alain
authors.initials: A
authors.lastname: Riaublanc
authors.forename: François
authors.initials: F
authors.lastname: Mariette
mesh_terms: D002364:Caseins / Q000032:analysis*; D003611:Dairy Products; D004058:Diffusion; D005223:Fats / Q000032:analysis*; D005524:Food Technology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008433:Mathematics; D014867:Water / Q000737:chemistry*
chemical_list: D002364:Caseins; D005223:Fats; D014867:Water