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R. D. LUDESCHER, Dept. of Food Science, Rutgers, The State Univ. of New Jersey, 65 Dudley Rd., New Brunswick, NJ 08901-8520 Foods and food ingredients are heterogeneous over distance scales ranging from nanometers to centimeters; structural heterogeneities include, for example, the surfaces of proteins, regions of triple helix in gelatin, adsorbed polymer layers on emulsion droplets, crystal nuclei, fat droplets, starch granules, ice crystals, and surface films within foams. Structural features at any distance scale may in principle affect the macroscopic quality and stability of the finished food by modulating viscoelastic properties, the rates of chemical reactions, the extent of physical processes, nutritional availability, or sensory appeal. Any rational, as opposed to empirical, attempt to lower the caloric content of foods while maintaining appropriate quality must be based on a detailed understanding of how food structure is generated and maintained by interactions among processing operations and food components. Luckily, recent advances in both theory and technology have generated a variety of novel and extremely powerful techniques for collecting physical and chemical information on biomaterials at distance scales below one micron. This talk will review those novel imaging techniques that can provide information not only about the structural features of foods on distance scales from 1-1000 nm, but also can provide specific information about the biophysical properties of food materials on these distance scales. These techniques include confocal and near field optical scanning fluorescence microscopy, which have reached the analytical limit of the detection and characterization of single molecules, and scanning probe techniques that can provide detailed information about how the structural, rheological, or electrical properties of a surface vary on the nanometer scale as well as providing specific details about chemical interactions between individual molecules.
Session 8, Physics and chemistry of modifying food for caloric reduction
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