Probing protein hydration and aging of food materials by the magnetic field dependence of proton spin-lattice relaxation times.
Most cheeses can be considered as solid emulsions of milk fat in a matrix of water and proteins. Regions of each of the phases can be liquid during processing and maturation. Identifying these regions and monitoring changes in them is important as a prelude to controlling the structure of the final cheese. We concentrate on the behavior of water in the vicinity of proteins as a function of cheese aging. Our method utilizes nuclear magnetic relaxation dispersion (NMRD) associated with the frequency dependence of water spin-lattice relaxation rates using the field cycling NMR technique. This method provides insight into the dynamical behavior of water molecules on a very large time scale. Moreover, we can distinguish between molecular motion in bulk and motion in the vicinity of a source of relaxation, such as proteins. A fit of our dispersion data using a theory developed by J.-P. Korb and R.G. Bryant (J. Chem. Phys. 115 (2001) 23) allowed us to determine the degree of hydration of proteins as a function of aging. In particular, we find that protein hydration increases with ripening.
Godefroy
Sophie
S
MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand.
Korb
Jean-Pierre
JP
Creamer
Lawrence K
LK
Watkinson
Philip J
PJ
Callaghan
Paul T
PT
D002611:Cheese / Q000032:analysis*; D005223:Fats / Q000032:analysis*; D005524:Food Technology; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D011506:Proteins / Q000737:chemistry*; D011522:Protons; D014867:Water / Q000032:analysis*
D005223:Fats; D011506:Proteins; D011522:Protons; D014867:Water