Magnetic resonance imaging in food science

Part 1. Macroscopic Distance Scale ................................ 1 1. Résumé of MRI Methodology ................................................ 3 1.1 Introduction ........................................................... 3 1.2 Phase Coherence and Fourier Conjugate Variables in NMR .................................................. 3 1.3 Higher-Order Combinations of Fourier Conjugates ............................................................ 10 1.4 Modulus and Phase Images .................................. 14 1.5 Statistical Aspects of MRI ...................................... 15 1.6 Fourier Transformation of the Radio- Frequency Waveform: Slice Selection ................... 17 1.7 Fourier Transformation of the Gradient Modulation: Motional Spectra and FD-MG-NMR ......................................................... 20 1.8 Spin and Gradient Echoes: Contrast in k- Space Imaging ...................................................... 22 1.9 Fast Imaging Methods ........................................... 26 1.10 Chemical Shift Imaging .......................................... 31 2. MRI and Food Processing: Mapping Mass Transport and Phase Behavior .............................................................. 35 2.1 Introduction ........................................................... 35 2.2 MRI and Process Optimization .............................. 36 2.3 Drying .................................................................... 38 2.4 Rehydration ........................................................... 55 2.5 Freezing and Freeze-Thawing ............................... 60 iv Contents This page has been reformatted by Knovel to provide easier navigation. 2.6 Freeze-Drying ....................................................... 68 2.7 MRI and Miscellaneous Processing Operations ............................................................. 73 2.8 MRI and New Processing Technologies ................ 74 3. MRI and Food Processing: Mapping Temperature and Quality .................................................................................... 76 3.1 MRI and Temperature Mapping ............................. 76 3.2 MRI and Food Quality Factors ............................... 87 4. Flow Imaging and Food Rheology ........................................ 102 4.1 Introduction ........................................................... 102 4.2 Principles of Flow Imaging ..................................... 103 4.3 Basic Rheology ..................................................... 105 4.4 MRI and Tube Viscometers ................................... 108 4.5 MRI and Rotational Viscometers ........................... 111 4.6 Solid Suspensions ................................................. 114 4.7 MRI and Computational Fluid Dynamics ................ 116 4.8 Flow and Quality Assurance .................................. 117 4.9 Extrusion ............................................................... 118 4.10 Flow in Bioreactors ................................................ 121 4.11 Mixing and Turbulence .......................................... 123 4.12 Velocity Distributions ............................................. 127 4.13 Displacement Imaging of Complex Flows .............. 128 5. Solid-Imaging Techniques ..................................................... 134 5.1 Solid Linewidths .................................................... 134 5.2 Solid Imaging and Food Science ........................... 135 5.3 Stray-Field Imaging ............................................... 137 5.4 Phase-Encoding Solid Imaging .............................. 143 5.5 Sinusoidal Gradient-Echo Imaging ........................ 148 6. On-Line MRI for Process Control and Quality Assurance .............................................................................. 152 6.1 Introduction ........................................................... 152 6.2 Constraints Imposed by Spin Physics .................... 153 Contents v This page has been reformatted by Knovel to provide easier navigation. 6.3 Nonspatially Resolved On-Line NMR .................... 156 6.4 Spatially Resolved On-Line NMR .......................... 157 7. Whole-Plant Functional Imaging ........................................... 160 7.1 Introduction ........................................................... 160 7.2 Functional Root Imaging ........................................ 162 7.3 Transport in Intact Plants ...................................... 162 7.4 Functional Brain Imaging and Consumer Science ................................................................. 164 8. Unconventional MRI Techniques .......................................... 166 8.1 Introduction ........................................................... 166 8.2 Rotating-Frame Imaging ........................................ 166 8.3 Multinuclear Imaging ............................................. 170 8.4 NMR Force Microscopy ......................................... 173 Part 2. Microscopic Distance Scale ................................. 177 9. Microimaging and NMR Microscopy ..................................... 179 9.1 Introduction ........................................................... 179 9.2 Applications of NMR Microimaging to Cellular Tissue ................................................................... 179 9.3 Microimaging Processing Effects in Tissue ............ 188 9.4 Intracellular Microimaging ...................................... 196 9.5 Microscopic Transport Models for Cellular Tissue ................................................................... 202 10. Microstructure and Relaxometry ........................................... 205 10.1 Introduction ........................................................... 205 10.2 Water Proton Relaxation in Microscopically Heterogeneous Systems ....................................... 205 10.3 Relaxation Effects of Internal Field Gradients ........ 234 10.4 Microstructure and the Microbial Safety of Foods .................................................................... 239 11. Probing Microstructure with Diffusion .................................... 242 11.1 Introduction ........................................................... 242 11.2 Diffusion-Weighted Pulse Sequences .................... 242 vi Contents This page has been reformatted by Knovel to provide easier navigation. 11.3 Diffusion Propagator and Microstructure ............... 244 11.4 Susceptibility Effects on Diffusion Measurements ....................................................... 251 11.5 Coupled Relaxation and Diffusion ......................... 252 11.6 Diffusion in Multicompartment Systems ................. 253 11.7 Anomalous Diffusion ............................................. 254 11.8 Microstructure-Weighted k-Space Imaging ............ 255 11.9 Constant-Gradient CPMG and Stimulated- Echo Studies ......................................................... 256 11.10 Microstructural Determination in Food Matrices ................................................................ 259 Part 3. Molecular Distance Scale ..................................... 265 12. Molecular Origins of Relaxation Contrast .............................. 267 12.1 Introduction ........................................................... 267 12.2 Relaxation in a Single Proton Pool ........................ 267 12.3 Water Proton Transverse Relaxation ..................... 270 12.4 Water Proton Longitudinal Relaxation ................... 284 12.5 Water Proton Rotating-Frame Relaxation .............. 288 12.6 Low-Water-Content Homogeneous Systems ......... 290 Appendix A ...................................................................... 298 Appendix B ...................................................................... 299 13. Molecular Factors Influencing the Diffusion and Transfer of Water Magnetization ........................................... 301 13.1 Introduction ........................................................... 301 13.2 Molecular Factors Influencing Diffusion Contrast ................................................................ 301 13.3 Magnetization Transfer .......................................... 305 13.4 Multistate Theory of Water Relations in Foods .................................................................... 308 References ................................................................................... 316