Pulsed gradient spin-echo studies of water in foods

Pulsed gradient spin-echo (PGSE) studies of water in foods 

The theoretical form of S(q, A, r) is particularly simple for water diffusion in spatially uniform solutions or gels. For these 

Here T2 is the transverse relaxation time and D is the effective water-diffusion coefficient. In protein or polysaccharide solutions or gels there is fast exchange between water molecules in the bulk with those interacting with the macromolecule surface. There is also fast proton exchange between water and macromolecule protons. Both effects imply that D = /WZ)W + fsDs, where/w and/s are the water proton fractions in the bulk phase and surface respectively (/s +fw— 1) and Ds is the macromolecule diffusion coefficient. Since Ds Z)w, the second term is negligible so that D = (1 -/S)Z)W. This predicts 

Most recently these ideas have been combined with a numerical cell model to relate S(q, A, r) to cell structure in plant parenchyma tissue.143 Using PGSE data for apple tissue a value for the plasmalemma membrane permeability was estimated. The application of this numerical cell model to mammalian tissue might enable quantitative interpretation of diffusion weighted contrast in clinical MRI. Table 6 lists a number of other applications of the PGSE method to food-related materials, although few of these studies have attempted to explore systematically the whole of the three-dimensional q—A—r space. 

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See also in sourсe #XX -- [ ]

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