title: Quantitative characterization of food products by two-dimensional D-T2 and T1-T2 distribution functions in a static gradient.
abstract: We present new NMR techniques to characterize food products that are based on the measurement of two-dimensional diffusion-T2 relaxation and T1-T2 relaxation distribution functions. These measurements can be performed in magnets of modest strength and low homogeneity and do not require pulsed gradients. As an illustration, we present measurements on a range of dairy products that include milks, yogurt, cream, and cheeses. The two-dimensional distribution functions generally exhibit two distinct components that correspond to the aqueous phase and the liquid fat content. The aqueous phase exhibits a relatively sharp peak, characterized by a large T1/T2 ratio of around 4. The diffusion coefficient and relaxation times are reduced from the values for bulk water by an amount that is sample specific. The fat signal has a similar signature in all samples. It is characterized by a wide T2 distribution and a diffusion coefficient of 10(-11) m2/s for a diffusion time of 40 ms, determined by bounded diffusion in the fat globules of 3 microm diameter.
authors.affiliation: Schlumberger-Doll Research, 36 Old Quarry Road, Ridgefield, CT 06877, USA. hurlimann@slb.com
authors.forename: Martin D
authors.initials: MD
authors.lastname: Hürlimann
authors.forename: Lauren
authors.initials: L
authors.lastname: Burcaw
authors.forename: Yi-Qiao
authors.initials: YQ
authors.lastname: Song
mesh_terms: D003611:Dairy Products / Q000032:analysis; D004041:Dietary Fats / Q000032:analysis; D005504:Food Analysis; D006207:Half-Life; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D014867:Water / Q000032:analysis
chemical_list: D004041:Dietary Fats; D014867:Water