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Monitoring changes in feta cheese during brining by magnetic resonance imaging and NMR relaxometry

2011-12-01
ALTAN, Aylin
Öztop, Halil Mecit
MCCARTHY, Kathryn L.
MCCARTHY, Michael J.
Magnetic resonance imaging (MRI) and NMR relaxometry were used to monitor changes in feta cheese during 169 h of brining at 4.8%, 13.0% and 23.0% salt solutions. Image and relaxation data were acquired to study salt uptake and water loss due to dehydration of cheese during brining. Saturation recovery and Carr-Purcell-Meiboom-Gill (CPMG) sequences were used to determine the longitudinal relaxation (T-1) and the transverse relaxation (T-2) times, respectively. Signal intensities of T-2 weighted images decreased during 169 h of brining. An excellent linear correlation between the average signal intensity and the water content was obtained (R-2 = 0.984). The T-1 values of cheese brined at 4.8% were almost constant but T-1 values decreased for both 13.0% and 23.0% salt brined cheeses. Analysis of the CPMG decays gave relaxation spectra containing two components which decreased during brining. The short component T-2a was highly correlated with salt content (R-2 = 0.974). Results showed that NMR and MRI can be used to follow salt uptake and changes in water content in cheese during brining. (C) 2011 Elsevier Ltd. All rights reserved.