Effects of Freezing on Water Diffusion Properties in Poultry Meat: a µDTI Preliminary Study

In this preliminary work fresh and frozen-thawed chicken breast samples were investigated by means of Diffusion Tensor Micro Imaging (µDTI) with the aim of looking for changes in the anisotropic diffusion properties of water upon freezing and storage at low temperature. Four groups of samples were evaluated (G1-G4), namely fresh samples (G1), samples frozen in liquid N2 and stored at -30 °C for 1 day (G2), samples frozen in liquid N2 and stored at -30 °C for 11 days (G3) and samples frozen at -30°C and stored for 11 days (G4). Non parametric LDA of the most important rotationally invariant parameters obtained from the µDTI data reveals a significant difference (P < 0.001) between fresh and frozen samples. Analysis of the LDA biplot of our data (below) suggests that, contrary to what could be expected, water anisotropy increases upon freezing, probably because of a lateral shrinkage of the meat fibers produced by ice crystals growth in the extracellular spaces. http://www.biopolymersolutions.co.uk/nmr/PDF/posters/Venturi.pdf