Quantitative characterization of food products by two-dimensional D-T2 and T1-T2 distribution functions in a static gradient

We present new NMR techniques to characterize food products that are based oil the measurement of two-dimensional diffusion-T-2 relaxation and T-1-T-2 relaxation distribution functions. These Measurements call 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 T-1/T-2 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 T-2 distribution and a diffusion coefficient of 10(-11) m(2)/s for a diffusion time of 40 ms, determined by bounded diffusion in the fat globules of 3 mu m diameter. (c) 2005 Elsevier Inc. All rights reserved.