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dc.contributor.supervisor Page, John (Physics and Astronomy) en
dc.contributor.author Fan, Yuanzhong
dc.date.accessioned 2007-09-14T17:54:00Z
dc.date.available 2007-09-14T17:54:00Z
dc.date.issued 2007-09-14T17:54:00Z
dc.identifier.uri http://hdl.handle.net/1993/2831
dc.description.abstract This thesis is based on observations of the physical properties of wheat flour dough using ultrasonic measurements. Three frequency ranges were used in the study, low frequencies (near 40 kHz), intermediate frequencies (1 to 5 MHz, where bubble resonance effects are apparent), and high frequencies (near 20 MHz). Doughs mixed under different head space air pressures, from vacuum to atmospheric pressure, as well as under nitrogen, were studied at low frequency to investigate their relaxation behavior. Subsamples from ambient dough and vacuum dough displayed differences in the dependence of velocity and attenuation on time after compression, but no post mixing relaxation effect was apparent. A critical headspace pressure of approximately 0.16 atmospheres determined whether vacuum-like or ambient-like relaxation was observed. A peak in attenuation and changes in ultrasonic velocity were observed around the bubble resonance frequency, and these ultrasonic parameters changed substantially as a function of time. A bubble resonance model was used to interpret the results around the bubble resonance frequency, and bubble size distributions were estimated for ambient and vacuum dough from the ultrasonic data. For the high frequency range, a molecular relaxation model was used to interpret the results. Different fast relaxation times were observed for ambient dough (5 ns) and vacuum dough (1 ns). This relaxation time may be associated with conformational rearrangements in glutenin inside the dough matrix. These experiments have enabled dough relaxation to be probed over a very wide range of time scales (from ns to hours), and will lead to a better understanding of the role of dough matrix and gas cell effects on the physical properties of wheat flour doughs. en
dc.format.extent 2725324 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US
dc.subject ultrasound en
dc.subject dough en
dc.subject bubble size distribution en
dc.subject relaxation en
dc.title Using ultrasound to investigate relaxation and resonance phenomena in wheat flour dough en
dc.degree.discipline Physics and Astronomy en
dc.contributor.examiningcommittee Scanlon, Martin G. (Food Science) Frederiksen, Andrew (Geological Science) en
dc.degree.level Master of Science (M.Sc.) en
dc.description.note October 2007 en


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