Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 176-182). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 176-182). Also available on the Internet.

No description available.

Variable-temperature Fourier transform infrared spectroscopy can be employed to monitor the denaturation and aggregation of proteins during heat treatment. Information on the changes that occur in protein secondary structure upon heating is provided by detailed examination of the amide I band, as different protein conformations have characteristic amide I frequencies. The objectives of the present study were: (i) to study the changes in protein structure that occur during gelation of whey protein isolate (WPI) and (ii) to correlate the changes in protein structure observed under different physico-chemical conditions to rheological properties of WPI gels prepared under the same conditions. / The FTIR spectra of D2O solutions of WPI at different pHs, ranging from 3 to 10, were recorded as the temperature of the solution was increased from room temperature to 95°C in 5°C increments. In all the solutions studied, the formation of two new bands at 1618--1623 cm -1 and 1678--1684 cm-1 was observed upon heating; these bands are characteristic of aggregate formation and have been previously assigned to antiparallel beta-sheet structure. As the pH increased from 3 to 10, the aggregation temperature of WPI decreased from 85°C to 65°C. / The rheological properties of WPI gels were studied by employing an Instron Universal Testing Machine. The Instron measurements demonstrated that protein concentration, heating temperature, and heating and cooling time are directly related to gel strength. The changes in gel strength as a function of cooling time (for gels prepared by heating at 75°C for 45 min) were correlated to FTIR spectral data for WPI solutions subjected to the same treatment.

No description available.

Call number: LD2668 .T4 1984 M33 / Master of Science

Hyperbaric pressure has been shown to affect the secondary structure of whey proteins such as beta-lactoglobulin (beta-lg). There is limited research, however, regarding the optimal conditions by which pressurization of whey proteins could lead to irreversible changes in secondary structure including the reduction of intramolecular disulfide bonds. Irreversible changes in protein conformation and breakage of disulfide bonds of whey proteins induced by high pressure might result in an increase in their digestibility and a reduction of allergenicity. Hence, the overall objective was to explore the capability of hyperbaric pressure to alter irreversibly the secondary structure of whey proteins and thereby alter their allergenic and nutritional properties. The behaviour of different genetic variants of beta-lg was studied employing variable-pressure Fourier transform infrared (FTIR) spectroscopy to establish the optimum pressures needed for their denaturation. The results showed reversible effects of pressures up to 12.0 kbar on the secondary structure of three main genetic variants of beta-lg. The individual response of the genetic variants to pressure was distinguishable despite their subtle structural differences. Pressure-induced conformational changes were studied separately in bovine serum albumin, Ca++-saturated alpha-lactalbumin and Ca ++-free alpha-lactalbumin by FTIR spectroscopy. The studies revealed that the presence of Ca++ ion and the number of disulfide bonds protects the protein molecules against pressure. As whey proteins appeared to be resistant to denaturation upon single applications of high pressure up to 1200 MPa, we developed a novel pressure processing using a combination of pulse and continuous modes at lower pressures of 400 MPa which led to irreversible denaturation of whey protein structure and disulphide bond breakage. Weanling rats fed with whey protein isolates treated by this novel low pressure processing technique showed enhanced grow

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 151-159). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 151-159). Also available on the Internet.

No description available.