The impact of cooking on meat microstructure studied by low field NMR and Neutron Tomography

We studied the impact of temperature of cooking on meat microstructure. The cooking temperature was verified by calorimetry, showing the disappearance of endothermic peaks when cooking temperature was increased. These observations correspond to the denaturation of different protein fractions at specific temperatures. H-1-low field NMR and neutron tomography were used to further understand the relationship between the observed protein denaturation and changes in meat microstructure after heating. Hahn's echo and solid echo NMR sequences were applied to observe fast relaxation time corresponding to rigid protons. These protons were found to be associated with pools of protons with a strong interaction with the meat matrix. Their relaxation times (T-2) are of order of 500-900 mu s (for Hahn's echo sequence) and 10 mu s (for solid echo's sequence). These protons become more rigid upon increasing the temperature. 3D neutron tomography analysis demonstrated the defects created by the contraction of meat fibers and allowed measurement of their volume, which increase for the highest cooking degrees. This analysis allowed classification of the defects as a function of their position (surface or interior) and size (threshold 0.075 % v/v). Our results demonstrate that large defects increase increasing cooking temperature and are located at the surface of the meat slice.