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State Diagram (state + diagram)
Selected AbstractsExtending the Pressure,Temperature State Diagram of MyoglobinHELVETICA CHIMICA ACTA, Issue 3 2005Filip Meersman The pressure,temperature (P,T) diagram of proteins proposed by Hawley concerns the equilibrium between native and denatured forms. However, the importance of protein aggregation is increasingly recognized, and it has been suggested that certain aggregated states represent alternative folds of the polypeptide chain. Here, we present a P,T -diagram for myoglobin in which we include the aggregated state and suggest to call it a P,T -state diagram, as not all boundaries are true equilibrium transitions. We observe by Fourier transform infrared spectroscopy that increasing temperature causes the protein to aggregate, but that a subsequent further temperature increase results in the dissociation of this aggregate. Moreover, we observe that moderate pressures stabilize myoglobin against thermal denaturation. We hypothesize that this effect originates from the volume changes associated with the aggregation transition. [source] Phase Behavior of a Meat-Starch Extrudate Illustrated on a State DiagramJOURNAL OF FOOD SCIENCE, Issue 8 2002C.I. Moraru ABSTRACT: The phase behavior of a meat-starch extruded system was illustrated on a state diagram. A mixture of meat and potato granules (1.48:1) was extruded with a twin-screw extruder. The extrudates were equilibrated at relative humidities between 0 to 88% and their glass transitions were determined. Starch and proteins were phase separated at macromolecular level and retained their own phase transitions. The state diagram of the system showed that proteins dictated the texture of the mixed system, with starch contributing to the high value of the mechanical properties. Water had a plasticizing effect on both biopolymers. At room temperature, the extrudates with aw < 0.32 were glassy, while those with aw > 0.57 were rubbery. [source] Extending the Pressure,Temperature State Diagram of MyoglobinHELVETICA CHIMICA ACTA, Issue 3 2005Filip Meersman The pressure,temperature (P,T) diagram of proteins proposed by Hawley concerns the equilibrium between native and denatured forms. However, the importance of protein aggregation is increasingly recognized, and it has been suggested that certain aggregated states represent alternative folds of the polypeptide chain. Here, we present a P,T -diagram for myoglobin in which we include the aggregated state and suggest to call it a P,T -state diagram, as not all boundaries are true equilibrium transitions. We observe by Fourier transform infrared spectroscopy that increasing temperature causes the protein to aggregate, but that a subsequent further temperature increase results in the dissociation of this aggregate. Moreover, we observe that moderate pressures stabilize myoglobin against thermal denaturation. We hypothesize that this effect originates from the volume changes associated with the aggregation transition. [source] Phase Behavior of a Meat-Starch Extrudate Illustrated on a State DiagramJOURNAL OF FOOD SCIENCE, Issue 8 2002C.I. Moraru ABSTRACT: The phase behavior of a meat-starch extruded system was illustrated on a state diagram. A mixture of meat and potato granules (1.48:1) was extruded with a twin-screw extruder. The extrudates were equilibrated at relative humidities between 0 to 88% and their glass transitions were determined. Starch and proteins were phase separated at macromolecular level and retained their own phase transitions. The state diagram of the system showed that proteins dictated the texture of the mixed system, with starch contributing to the high value of the mechanical properties. Water had a plasticizing effect on both biopolymers. At room temperature, the extrudates with aw < 0.32 were glassy, while those with aw > 0.57 were rubbery. [source] Characterization of deep-fat frying in a wheat flour,water mixture model using a state diagramJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2007Pariya Thanatuksorn Abstract BACKGROUND: Crispness is an important characteristic to be controlled in deep-fat fried products. The physical state of food polymers influences the development of cellular structure and textural qualities of fried food. Glassy state is believed to play an important role in the mechanical properties of low-moisture food. Therefore, an understanding of the physicochemical phenomena in the development of fried food structure using a state diagram of the frying process is discussed. RESULTS: Wheat flour models containing 400 and 600 g kg,1 initial moisture content were fried in frying oil at 150 °C for 1,7 min. Thermal properties of wheat flour, structure alteration and textural properties of fried samples were evaluated. The porous structure continuously enlarged when the sample was in the rubbery state. As the frying time was prolonged, the state of the product became glassy due to a decrease in water content, resulting in the ceasing of porous enlargement. Conclusion: The results revealed that physicochemical changes during frying influence the alteration of microstructure and quality of fried food, and the state diagram could be applied to explain the formation of microstructure during the frying process and used as a decision-making tool to choose the proper conditions to provide desirable qualities in fried food. Copyright © 2007 Society of Chemical Industry [source] Modular Chiral Bidentate Phosphonites: Design, Synthesis, and Application in Catalytic Asymmetric Hydroformylation ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2008Baoguo Zhao Dr. Abstract A new class of C2 -symmetric chiral bidentate phosphonite ligands has been synthesized in moderate to good yields from readily available starting materials. Application of these air-stable chiral phosphonites in the RhI -catalyzed asymmetric hydroformylation of styrene derivatives, vinyl acetate, and allyl cyanide afforded the corresponding chiral aldehydes with high regio- and enantioselectivities under mild reaction conditions. The modular nature of the ligands allows fine-tuning of the selectivities through judicious modifications of the substituents on the ligand backbone. X-ray structural analysis of the catalyst precursor suggested that the steric hindrance caused by the protruding remote substituents of the ligands into the vicinity of the metal center might be an important factor for the enantio-control of the reaction, whereas the sense of asymmetric induction can be rationalized on the basis of a trigonal-bipyramidal transition state diagram. [source] Relationship between ice recrystallisation rates and the glass transition in frozen sugar solutionsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2002Steve Ablett Abstract The increase in ice crystal size that occurs through recrystallisation when many frozen products such as ice cream and frozen desserts are stored is one of the major factors contributing to the perceived deterioration of the product by the consumer. In order to reduce the rate of deterioration, a detailed understanding of the fundamental mechanism is needed. This study demonstrates that ice recrystallisation rates in a series of frozen sugar solutions are strongly correlated with the molecular mobilities of the water and solute molecules as measured by time domain nuclear magnetic resonance. The study also demonstrates that the proximity to the glass transition temperature as described by state diagrams correlates well with the measured ice recrystallisation rates. The temperature dependence in these systems is described by Williams, Landel and Ferry theory. © 2002 Society of Chemical Industry [source] | ||||||||||||||||||||||