Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2009. / Includes bibliographical references (leaves 179-194). Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 299-304). Available also in a digital version from Dissertation Abstracts.

We investigated the depletion interactions of colloids and hindrance behavior of hard and soft colloidal particles near neighboring walls. We first used numerical modeling to compute depletion interaction strengths for simple geometries which eventually guided our experiments to make interactions highly selective. The model helped us in identifying the important parameters to finetune these interactions and shed light on geometric design rules to optimize desirable shape-selective interactions on a variety of complex geometries. We further reported experimental studies that highlight the differences in the dynamics of hard and soft colloids under confinement using video microscopy and particle tracking. It was found that both soft sphere systems that we investigated (swollen polymer particles, core/shell microgels) behave differently from hard sphere systems under all degrees of confinement that were measured. Our findings suggest that soft sphere systems have lesser hindrance compared to hard sphere counterparts and the hindrance varies as a function of softness. In order to understand the soft sphere confinement dynamics more clearly, implications for future research are discussed.

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The current research was designed to determine the effects of different compositions of a pectin-based emulsion coating on the quality indices and shelf life extension of mango and cucumber. The fruits were treated with pectin-based coating (coated) or kept as such (control), and stored under different temperatures and relative humidities. Samples of fruits were then tested periodically to note the changes in quality as determined by visual observation, weight loss, respiration rate, color, firmness, pH, titrable acidity (TA), total soluble solids (TSS), chlorophyll content, and decay. Coated fruits displayed retarded color development, higher TA, higher chlorophyll content, greater firmness, lower pH, and lower TSS. Loss in weight and CO 2 evolution were also reduced significantly. The results of this research suggested that pectin-based coating increased the shelf life of mango and cucumber more than 100% without perceptible losses in quality.

An in-depth study of the biodeterioration of the Hulett Aluminium hot roll mill emulsion, Prosol, was conducted. Samples of the emulsion in use at the hot roll mill were taken from various areas of the emulsion reticulation system in order to identify regions of highest microbial contamination. Standard plate count techniques and diagnostic procedures were employed to quantify and identify the microorganisms in these samples. In some of the highly contaminated areas of the emulsion reticulation system, microorganisms exceeded lxlO'CFUml'1 emulsion. A range of bacteria was identified which included members of the genera: Bacillus; Pseudomonas; Escherichia; Enterobacter; Sporosarcina; Micrococcus; Aeromonas; Chromobacterium and Desulfovibrio. Various fungi, including several yeasts, were also isolated and some of the filamentous spore-forming types were identified zsAspergillus spp.; Penicillium spp. and a Cladosporium sp. A visual scale was developed to assess the growth rate of the isolated microorganisms on a range of specific media containing various emulsion components as carbon and energy source. Although the results obtained by using this scale were not conclusive, a few biodegradable components were nonetheless identified. It was found that mixed cultures of the above microorganisms had a greater biodeteriorative effect on the emulsion than did any of the pure cultures when applied separately. This suggested complex microbial interactions were involved in the breakdown of the emulsion. A laboratory-scale model system representative of the Hulett Aluminium hot roll mill was designed and constructed to carry out a series of tests on unprotected and biocide-treated emulsions. A range of biocide concentrations were tested from which the minimum biocide inhibitory concentration was calculated. It was shown that microorganisms exposed to sublethal doses of the biocide Busan (active component glutaraldehyde) over a prolonged period of time, exhibited greater levels of tolerance and resistance to the biocide than did those microorganisms not previously exposed. It was deduced that less frequent, shock doses of biocide are more effective in the control and eradication of emulsion degrading microorganisms than are frequent, low level doses of the same biocide. In addition to the biocide studies, three imported so-called 'biostable' emulsions were evaluated as possible replacements for the susceptible Prosol. Of these three imported emulsions, two viz. HRF3 and Houghton Biostable were shown to be more resistant than Prosol to biodeterioration. After assessing the current hot roll mill management practices, a number of recommendations were made, including: the improvement of plant hygiene; education of the mill workers; improvement of emulsion monitoring; improvement of down-time management and improvement of biocide dosing regimes. Recommendations are also made for minimizing potential microbial growth in the new hot roll mill currently under construction at the Hulett Aluminium processing plant at Pietermaritzburg, South Africa. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

The physical properties and the stability of alcohol containing emulsions made with sodium caseinate using two types of oil, canola oil and coconut oil, were investigated. The region of emulsion stability was presented on ternary phase diagrams. Emulsion stability was limited to emulsion compositions in the range of sodium caseinate solutions between 32-68 %wt, oil contents between 10-53 %wt and ethanol concentrations from 8 to 32 %wt. The type of oil had a minor effect on emulsion stability, but stability was sensitive to ethanol content and casein/oil ratio. Emulsions were classified as Newtonian fluids, with high ethanol content (> 20 %wt) being low viscosity and those of low ethanol content (< 20 %wt) being of high viscosity. Analysis of emulsion droplet sizes showed that the presence of ethanol affected the average droplet size. From lipid oxidation determinations, there was no clear correlation between casein/oil ratio and concentration of lipid hydroperoxides

The physical properties and the stability of alcohol containing emulsions made with sodium caseinate using two types of oil, canola oil and coconut oil, were investigated. The region of emulsion stability was presented on ternary phase diagrams. Emulsion stability was limited to emulsion compositions in the range of sodium caseinate solutions between 32-68 %wt, oil contents between 10-53 %wt and ethanol concentrations from 8 to 32 %wt. The type of oil had a minor effect on emulsion stability, but stability was sensitive to ethanol content and casein/oil ratio. Emulsions were classified as Newtonian fluids, with high ethanol content (> 20 %wt) being low viscosity and those of low ethanol content (< 20 %wt) being of high viscosity. Analysis of emulsion droplet sizes showed that the presence of ethanol affected the average droplet size. From lipid oxidation determinations, there was no clear correlation between casein/oil ratio and concentration of lipid hydroperoxides