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Heat-induced changes in myofibrillar protein structures and myowater of two pork qualities. A combined FT-IR spectroscopy and low-field NMR relaxometry study.

Bertram HC, Kohler A, Böcker U, Ofstad R, Andersen HJ

Department of Food Science, Danish Institute of Agricultural Sciences, Research Centre Foulum, P.O. Box 50, DK-8830 Tjele, Denmark. HanneC.Bertram@agrsci.dk

Low-field NMR T(2) and Fourier transform infrared (FT-IR) measurements were performed on meat samples of two qualities (normal and high ultimate pH) during cooking from 28 degrees C to 81 degrees C. Pronounced changes in both T(2) relaxation data and FT-IR spectroscopic data were observed during cooking, revealing severe changes in the water properties and structural organization of proteins. The FT-IR data revealed major changes in bands in the amide I region (1700-1600 cm(-)(1)), and a tentative assignment of these is discussed. Distributed NMR T(2) relaxation data and FT-IR spectra were compared by partial least-squares regression. This revealed a correlation between the FT-IR peaks reflecting beta-sheet and alpha-helix structures and the NMR relaxation populations reflecting hydration water (T(2B) approximately 0-10 ms), myofibrillar water (T(21) approximately 35-50 ms), and also expelled "bulk" water (T(2) relaxation times >1000 ms). Accordingly, the present study demonstrates that definite structural changes in proteins during cooking of meat are associated with simultaneous alterations in the chemical-physical properties of the water within the meat.

Published 1 March 2006 in J Agric Food Chem, 54(5): 1740-6.
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