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The gelling characteristics of whey proteins is governed by factors which affect the structural properties of the protein. To understand this structure gelling relationship, the following factors were investigated; protein concentration, heating temperature and time, pH, NaCl and sugars. The effect of these factors on the molecular structure and gelatin properties of whey protein concentrate (WPC), $ beta$-lactoglobulin ($ beta$-lg), $ alpha$-lactalbumin ($ alpha$-lac) and bovine serum albumin (BSA) were studied using polyacrylamide gel electrophoresis, HPLC, mass spectrometry, differential scanning calorimetry and Fourier transform infrared spectroscopy. The results showed that protein concentration affected textural properties without affecting the molecular structure of the whey proteins while heating temperature, pH and NaCl affected both molecular structure and the textural characteristics. NaCl and sugars increased the stability of whey proteins to thermal denaturation but decreased gel formation. $ beta$-lg formed an opaque gel at pH 3 and a translucent gel at pH 9; the peak temperature of denaturation was 84$ sp circ$C at pH 3 and 70$ sp circ$C at pH 9. At both acid and alkaline pH, denaturation of $ beta$-lg resulted in the formation of intermolecular $ beta$-sheet structures associated with aggregation. These $ beta$-sheet aggregate structures were also observed when $ alpha$-lac was heated at pH 3 and 5 but not at pH 7 and 9. At pH 7, heating $ alpha$-lac resulted in a loss of $ alpha$-helix, $3 sb{10}$-helix and $ beta$-sheet and an increase in turns. DSC showed two reversible transitions at 39.6$ sp circ$C (A) and 64.8$ sp circ$C (B). At pH 3, transition A was partially reversible (14%) while transition B was completely reversible. At pH 9, transitions A and B were completely irreversible and a translucent gel was formed. Bovine serum albumin (BSA) showed maximum stability to thermal denaturation at pH 5. Denaturation of BSA resulted in the loss of $

Lower critical solubility temperatures (LCST) have been measured for polyethylene (PE), polypropylene, ethylene-propylene copolymers, polybutene-1, polypentene-1 and poly 4-methylpentene-1 (P4MP1) in twenty-five isomeric alkanes. The LCST for PE are much lower than for branched polyolefins, especially in branched alkanes. The results are not predicted by the Prigogine-Flory-Patterson theory but are understood in terms of correlations of molecular orientations in the PE melt. / Fusion thermodynamics of P4MP1 confirm the existence of ordered conformations in the melt. The thermoreversible gelation of P4MP1 solutions depends on solvent and thermal history. It is studied by calorimetry, viscosimetry and wide angle X-ray diffraction. The gel crosslinks are presumably of a fringed-micellar nature and their formation is tentatively associated with the existence of helical conformations of P4MP1 in solution. The latter is also responsible for the obtaining of four different crystalline structures of P4MP1 from solutions and gels. Preliminary measurements of dynamic mechanical properties of P4MP1 gels are reported.

Thesis (PhDAppliedScience)--University of South Australia, 2003.

Thesis (doctoral)--Helsinki University of Technology, 2002. / Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Drexel University, 2006. / Includes abstract and vita. Includes bibliographical references (leaves 162-170).

No description available.

No description available.

Call number: LD2668 .T4 1985 M86 / Master of Science