Probing protein hydration and aging of food materials by the magnetic field dependence of proton spin-lattice relaxation times

• Published in: Journal of colloid and interface science Vol. 267; no. 2; pp. 337 - 342
• Main Authors: Godefroy, Sophie, Korb, Jean-Pierre, Creamer, Lawrence K, Watkinson, Philip J, Callaghan, Paul T
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 15.11.2003; Elsevier
• Subjects: Aging food materials; Biological and medical sciences; Cheese; Cheese - analysis; Dynamics; Fats - analysis; Field cycling NMR; Food industries; Food Technology; Fundamental and applied biological sciences. Psychology; Magnetic Resonance Spectroscopy; Milk and cheese industries. Ice creams; Models, Biological; Oil; Protein hydration; Proteins - chemistry; Protons; Spin-lattice relaxation time; Water; Water - analysis; Water; Oil; Dynamics; Protein hydration; Spin-lattice relaxation time; Field cycling NMR; Aging food materials; Cheese; Cheese ripening; Hydration; Oil water emulsion; Dairy product; NMR spectrometry; Protein
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/S0021-9797(03)00589-7

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.