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D. Z. ICOZ and J. L. Kokini. Dept. of Food Science, Rutgers, The State Univ. of New Jersey, Center for Advanced Food Technology, 65 Dudley Rd., New Brunswick, NJ 08901-8520 Understanding the rules that govern compatibility and miscibility of food biopolymers is critical to control their phase behavior, which in turn affects their processability, texture, functionality and stability. Our recent studies have shown that immiscibility occurs even in chemically like systems and miscibility depends not only on chemical compatibility, but also on sample preparation techniques. There are still intriguing questions, such as where the limits of miscibility are in terms of chemical structure and compatibility coupled with the thermodynamic barriers needed for miscibility to take place. The objectives of this study were to investigate the influence of chemical modifications on miscibility of dextrans with similar molecular weights and to study the phase behavior of the pure, standard dextran systems by analyzing their crystallization behavior. Standard dextrans were mixed separately with two chemical derivatives of dextran (dextran sulphate and diethylaminoethyl dextran) with similar molecular weights in different ratios. Molecular miscibility was assessed through glass transition temperature analysis using Differential Scanning Calorimetry (DSC). X-ray scattering patterns of seven pure, standard dextrans with weight-average molecular weights (Mw) ranging from 970 to 2,000,000 and that were stored at aw=0.75 and aw=0.93 were obtained. In the mixed systems, when electrostatic interactions became significant, miscibility at molecular level was no longer possible and phase separation occurred. For pure, standard dextrans, the degree of crystallinity decreased as Mw increased for samples stored at aw=0.75 and aw=0.93, since it was easier for small Mw dextrans to organize themselves macroscopically as compared to the higher Mw dextrans. The generated knowledge can benefit the food industry by controlling the design of new foods of desired structure and texture, as well as the quality improvement of existing foods.
Session 93, Carbohydrate: General
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