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Polymorphic Transformation (polymorphic + transformation)
Selected AbstractsContribution of the Starch, Protein, and Lipid Fractions to the Physical, Thermal, and Structural Properties of Amaranth (Amaranthus caudatus) Flour FilmsJOURNAL OF FOOD SCIENCE, Issue 5 2007D. Tapia-Blácido ABSTRACT:, Amaranth protein,lipid (PL) and protein (P) films were elaborated and compared with amaranth flour films in order to determine the contribution of the interactions between the biopolymer (starch and protein) and the lipids to the film properties. The films were made by the casting method, using the same glycerol concentration (0.9 g glycerol/100 g solution). A separation of the lipid fraction in the PL films and a polymorphic transformation of the corresponding fatty acids were observed by differential scanning calorimetry (DSC) and verified by an analysis of the microstructure by scanning electron microscopy (SEM). The flour films showed no separation of the lipid fraction, evidence that the lipids were strongly associated with the proteins and homogenously distributed throughout the starch network, contributing to the good mechanical properties when compared to the PL films and to the excellent barrier properties when compared to both the PL and P films. The protein-protein interactions also contributed to the mechanical properties of the flour films. The presence of proteins and lipids in the flour films had an important effect on film solubility, and also on the color and opacity of the films. This study showed that the flour film properties depended on the interactions formed by their polymers (starches and proteins) and by the lipid, on the distribution of these interactions within the film matrix and on the concentrations of each component in the film. [source] Nonlinear model predictive control for the polymorphic transformation of L -glutamic acid crystalsAICHE JOURNAL, Issue 10 2009Martin Wijaya Hermanto Abstract Polymorphism, a phenomenon where a substance can have more than one crystal forms, has recently become a major interest to the food, speciality chemical, and pharmaceutical industries. The different physical properties for polymorphs such as solubility, morphology, and dissolution rate may jeopardize operability or product quality, resulting in significant effort in controlling crystallization processes to ensure consistent production of the desired polymorph. Here, a nonlinear model predictive control (NMPC) strategy is developed for the polymorphic transformation of L -glutamic acid from the metastable ,-form to the stable ,-form crystals. The robustness of the proposed NMPC strategy to parameter perturbations is compared with temperature control (T-control), concentration control (C-control), and quadratic matrix control with successive linearization (SL-QDMC). Simulation studies show that T-control is the least robust, whereas C-control performs very robustly but long batch times may be required. SL-QDMC performs rather poorly even when there is no plant-model mismatch due to the high process nonlinearity, rendering successive linearization inaccurate. The NMPC strategy shows good overall robustness for two different control objectives, which were both within 7% of their optimal values, while satisfying all constraints on manipulated and state variables within the specified batch time. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Physicochemical, textural and viscoelastic properties of palm diacylglycerol bakery shortening during storageJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2010Ling-Zhi Cheong Abstract BACKGROUND: Diacylglycerol (DAG), which has health-enhancing properties, is sometimes added to bakery shortening to produce baked products with enhanced physical functionality. Nevertheless, the quantity present is often too little to exert any positive healthful effects. This research aimed to produce bakery shortenings containing significant amounts of palm diacyglycerol (PDG). Physicochemical, textural and viscoelastic properties of the PDG bakery shortenings during 3 months storage were evaluated and compared with those of commercial bakery shortening (CS). RESULTS: PDG bakery shortenings (DS55, DS64 and DS73) had less significant increments in slip melting point (SMP), solid fat content (SFC) and hardness during storage as compared to CS. Unlike CS, melting behaviour and viscoelastic properties of PDG bakery shortenings remained unchanged during storage. As for polymorphic transformation, CS contained only , crystals after 8 weeks of storage. PDG bakery shortenings managed to retard polymorphic transformation for up to 10 weeks of storage in DS55 and 12 weeks of storage in DS64 and DS73. CONCLUSION: PDG bakery shortenings had similar if not better storage stability as compared to CS. This is mainly due to the ability of DAG to retard polymorphic transformation from ,, to , crystals. Thus, incorporation of DAG improved physical functionality of bakery shortening. Copyright © 2010 Society of Chemical Industry [source] Raman tensor analysis of baddeleyite single-crystal and its application to define crystallographic domains in polycrystalline zirconiaPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2010Kyoju Fukatsu Abstract The angular dependence of polarized Raman intensity for the Ag and Bg modes was investigated and the full set of Raman tensor elements defined for a baddeleyite single-crystal, namely the monoclinic polymorph of zirconia (ZrO2). Based on the quantitative knowledge of the tensor elements, a method has been proposed for the determination of unknown crystallographic textures in monoclinic zirconia. An application of this method is also shown, which consists of a Raman analysis of crystal orientation on the microscopic scale in polycrystalline ZrO2 after its tetragonal-to-monoclinic (t,m) polymorphic transformation (i.e., occurred under an externally applied stress field). This working example not only confirms the well-known phenomenon of stress-induced phase transformation in polycrystalline zirconia, but also proves the existence of textured domain patterns in the monoclinic phase on a scale larger than that of individual grains. This finding might suggest that the structural and functional properties of polycrystalline zirconia after partial phase transformation should be reinterpreted with taking into account a crystallographic reorientation effect. [source] | ||||||||||