Chemical and Biomolecular Engineering - Theses
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ItemStructural instabilities in crystalline solids( 2014)Structural instabilities can be envisaged on various microstructural scales ranging from the “nano” (or atomic) to the “macro” (as one imagines for multi-phase materials). Thus the physical properties measured and techniques employed to research materials of interest for specific projects have been wide ranging. In the research summary section for each chapter, these properties and techniques have been briefly summarized. Separate thesis chapters deal with: various superconducting materials; materials exhibiting martensitic transformations; residual stresses in polycrystalline materials as studied by x-ray and neutron diffraction techniques; various dielectric materials, particularly ferro and piezoelectric materials; magnetic microstructures; and alloys developed for hollow cathodes for atomic absorption spectrometry.
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ItemSupramolecular polymers as building blocks for the formation of particles( 2014)Over the last two decades, there has been a growing interest in the development of supramolecular polymers, linear macromolecules whose monomeric components are held together by non-covalent interactions. Such supramolecular assemblies are commonly found in nature and are crucial for the function of living tissues and cells. The recent development of synthetic supramolecular polymers has shown promise for enhancing the properties of polymeric materials. Indeed, studies have shown that such materials have significant benefits when compared to conventional, covalently bound, polymers. These benefits are due to the ability of supramolecular assemblies to respond to stimulus, and to dynamically rearrange their structure in a manner unachievable using conventional, covalently bound polymers. Resemblances between the dynamics of synthetic supramolecular polymers and naturally occurring supramolecular polymers are suggestive of their potential for biomedical applications. In this trend, the most promising supramolecular polymer, cyclodextrin (CD) based polyrotaxanes (PRXs), is now emerging as a potential tool to synthetically form dynamic interfaces for applications in the biomedical field. The recent popularity of these polymers in this field is not only due to their inherent, non-covalent properties but also to the low cost, high engineerability and low toxicity of the components they are made of. In this work, CD-based PRXs have been used as building blocks to form particles that were designed for developments in drug delivery. Specifically, the properties specific to PRXs have been exploited to design particles with degradation or stimuli-based response. The unique characteristics of PRXs were found to translate into similarly unique characteristics of the assembled particles. Different approaches have been studied and their advantages and limitations are highlighted. Initial investigations were aimed at designing particles fitting the requirements in properties and specific characteristics highlighted by recent in vivo and in vitro studies. In this direction, we demonstrated controlled degradation of self-assembled PRX-based structures through stimuli triggered disassembly. Such control was also shown for PRX particles dynamically formed using a templated approach, for which disassembly through judicious selection of specific building blocks is highlighted. The use of the templated approach was shown to be more straightforward and versatile in its applications, laying out a framework to form and engineer particles using PRXs as a building block. Lastly, by using CD’s molecular mobility in the PRX as an additional handle for tuning; a “one block” polymer, able to reversibly segregate into multi-blocks leading to the formation of nanoparticles, was developed. This approach is particularly interesting as many responsive polymeric materials have their response due to a stretched-to-coiled transition of individual chain while we show here a transition between a mono-block like architecture to a multi-block like architecture. The preliminary results highlight the potential of PRXs as building blocks for applications in drug delivery systems.
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ItemSuccess factors for engineering students: learning strategy, interest, and intention( 2014)This thesis explores the success factors of engineering undergraduates at an institution in Australia and Malaysia. The main aim of this study is to investigate the relationships between learning strategy, interest, intention, and study success, and to test the causal pathways from the predictive factors to study success using the Structural Equation Modelling (SEM) procedure. The tested paths were guided by an established theory, the Theory of Reasoned Action (TRA). The multiple pathways to success and intentions were an outcome of this study which eventually produced two best-fit models of performance for each country. Another aspect of this study has been to qualitatively explore the similar learning factors based on their success story to provide detail explanations to the role of each learning factors to enable study success. This study further incorporates findings from the two studies to propose a conceptual framework for understanding the way engineering students’ approach learning towards achieving success. A newly proposed instrument was also designed based on elements suggested in the framework and using learning factors determined in the qualitative study. This study found that engineering students established very similar learning strategies regardless of study location, but were different in the way they develop interest and intention to learn. Findings of this research also provide evidence to supports the notion that integrating the intention (conative domain) with aspects of interest (affective domain) and strategy (cognitive domain) is useful to better understand ways student approaches learning and behaviours towards achieving success.
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ItemPeripheral nerve stimulation for the treatment of chronic neuropathic pain( 2014)Neuropathic pain is a chronic health condition with a severe impact on the quality of life of affected patients. The condition is often difficult to manage and refractory to traditional pain treatment strategies such as pharmacological management, physiotherapy and psychological therapy. Peripheral nerve stimulation has been proposed as an alternative treatment with numerous successful clinical reports. Nevertheless, the systematic understanding of the underlying mechanism of action is still limited. Efficacy studies in the form of randomised controlled trials have predominantly been conducted for occipital nerve stimulation to treat various headache conditions. Without trials of a wide range of neuropathic conditions, the commercial availability of approved medical devices is limited. The overall objective of this thesis was to advance towards the development of a peripheral nerve stimulation system for a small-scale clinical trial that will be used to gain a deeper understanding of the underlying mechanisms of pain modulation. Design features of electrode arrays and new stimulation strategies were tested in order to facilitate the development of advanced clinical peripheral nerve stimulation systems. The first part of the work consisted of the development of a small, wearable neural stimulator for the use in clinical trials. Chapter 2 presents the design and characterisation of the stimulator. It was shown that safe and efficacious neural activation could be achieved and the system will be suitable for use during a short-term clinical trial of electrode arrays with a percutaneous leadwire system. In the second part, a model electrode setup was used to investigate a bipolar stimulation strategy. Chapter 3 documents an electrophysiological study on the maximisation of the therapeutic window available for stimulation. An electrode screening strategy was developed in order to increase the efficiency of intra- and post-operative testing of stimulation arrays with a large number of electrode combinations. The third part of the work focussed on the development of single-source multipolar stimulation as a novel method to perform current focussing for increased selectivity of the neural activation. Chapter 4 presents the in vitro investigation that showed that a successful reduction of voltages at electrode sites other than the centre electrode was achieved when compared to monopolar stimulation. Furthermore, a significant improvement of the voltage reduction was also found compared to tripolar and common ground stimulation. The promising results from the in vitro tests were followed by an in vivo evaluation as presented in Chapter 5. However, the focussing effects found in vitro did not translate to functional benefits in vivo for the investigated setup. Rather, increased neural activation thresholds were found resulting in potentially higher power requirements for a clinical system. Monopolar stimulation was identified as the favourable mode under the tested conditions. In conclusion, the results of this thesis suggest that a safe and reliable, tailored electrode array in combination with a monopolar stimulation strategy forms a promising system in order to progress towards the overall objective, a short-term clinical trial. This will help to gain a deeper understanding of the underlying mechanism of action of peripheral nerve stimulation for the treatment of chronic neuropathic pain.
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ItemSimplified computational models for adsorbent screening and cycle design for cyclic adsorption cycles for post-combustion CO2 capture applications( 2014)Cyclic adsorption processes are a promising technology for CO2 capture from large emissions point sources. Thousands of adsorption materials have been developed for CO2 capture, but there is no accepted method of determining which adsorbents are truly promising for use in an industrial process. Detailed adsorption simulation software is available, but it requires significant computational time and expert users. Therefore, most researchers resort to crude isotherm analysis when evaluating materials, which can be misleading in many cases. In order to rapidly screen adsorbent materials, we have developed a novel simple pressure/vacuum swing adsorption (PSA/VSA) model which can be solved in less than one second using MATLAB while still approximating experimental data. We have used this model to rapidly screen different classes of adsorbents for post-combustion CO2 capture, determine the ideal operating conditions, and identify optimal adsorbent properties. Our study suggests that zeolite 13X is still the best material available for post-combustion CO2 capture from dry flue gas. However, purity, recovery, and specific power results can be much improved if materials are developed with ideal, yet reasonably achievable, properties. Our results also showed that thermal effects and selectivity are much more important to VSA performance than is CO2 adsorption capacity and that the ideal CO2 heat of adsorption for this process is between 35KJ/mol and 45KJ/mol. Temperature swing adsorption (TSA) has also gained much attention recently as a CO2 capture technology because of its low energy penalty. The main drawback of TSA is long cycle times which can take several hours to complete. In order the overcome this challenge, we have developed a hot product purge TSA cycle using structured supported amine adsorbents which can be used to capture CO2 at high throughput with purities and recoveries over 90%. We analyzed several configurations of this cycle in attempt to reduce the associated thermal energy requirement. We also found the ideal adsorbent isotherm parameters for this process from a range of feasible adsorbent capacities, heats of adsorption, and entropies of adsorption. Using these ideal isotherms, we were able to simulate a process with a thermal energy requirement as low as 2.9 GJ/ton CO2 for a 90°C feed and 2.3 GJ/ton CO2 for a 30°C feed. We also performed a case study on the integration of our process into a Victorian brown coal-fired power station based on thermal efficiency data from the Loy Yang B power station. Our calculations suggest that for this process, the parasitic energy can be as low as .5GJ/ton CO2 which is much lower than that which can be achieved using VSA. We also estimated the bed size factor for this process to be approximately 500 kg/TPD CO2 which is on the same order of magnitude as VSA.
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ItemMembrane processes for water recovery from brown coal flue gases( 2014)Victorian brown coal has a significantly higher moisture content compared to black coal. Hence, it is possible that significant quantities of water can be recovered from high temperature brown coal flue gases and recycled in the process given that it is a high enough purity. The presence of CO2 and SOx will result in acidic water that may cause corrosion issues. The use of membranes to selectively permeate water over other flue gas components such as N2 and CO2 has the potential to provide a water stream of high purity. While N2 is the major component in flue gas, in this instance the presence of CO2 also needs to be investigated because of its high acidity. This work considered the separation performance of Nafion 115, Sulphonated Poly (Ether Ether) Ketone (SPEEK) and 6FDA – TMPD (2, 2 – bis (3, 4 – dicarboxyphenyl) hexafluoropropane dianhydride – 2, 3, 5, 6 – tetramethyl – 1, 4 – phenylenediamine) at elevated temperatures. Water, CO2 and N2 permeation properties of these membranes were investigated on a novel high temperature mixed gas rig that utilized mechanical agitation to eliminate concentration polarization. The permeation of water, CO2 and N2 through Nafion 115 was investigated as a function of water activity at 70 – 150 °C. It was found that all permeances increased with increasing water activity but reduced with increasing temperature. This data was supplemented by sorption analysis at lower temperature which conversely showed decreasing solubility as temperature increased. The sorption results were modelled using a modified Dual Mode Sorption Model where Arrhenius expressions were used to model the effect of temperature on the water concentration absorbed into the polymer. The changes in solubility and permeance with water activity were attributed to membrane swelling as water activity increased. A comparison with a thinner perfluorosulphonic acid polymer (Fumapem F - 920) from an alternate supplier suggested that permeance did not scale linearly with membrane thickness, reflecting non – linear water activity gradients within the membrane and thus inhomogeneity in membrane swelling. The effect of temperature on water vapour and CO2 permeation properties of Sulphonated Poly (Ether Ether) Ketone (SPEEK) with two different ion exchange capacities (IEC) were investigated. These were Fumapem E - 630 and Fumapem E - 540 - GF with IEC 1.6 meq/g and IEC 1.9 meq/g, respectively. It was found that both permeabilities increased with increasing water activity due to increased water solubility as water concentration increased. This was supported by FTIR spectra that measured peaks for water sorbed into the SPEEK polymer and confirmed the presence of the water as clusters. Both water vapour and CO2 permeabilities increased as temperature increased up to 50 °C. This was due to the increase in diffusion of the penetrating molecules. However as temperature increased further, increased water uptake appeared to result in significant formation of water clusters that hindered the diffusion of isolated molecules. This decrease in diffusion coupled with a reduction in solubility with increasing temperature resulted in a significant drop in water permeability above 50 – 70 °C. Similar results have been obtained by other researchers and were attributed to the reduction in solubility overcoming the increase in diffusivity with increasing temperature. The permeabilities at 70 – 150 °C were modelled using Arrhenius expressions. Activation energies of permeation of ~ -46 kJ/mol for IEC 1.6 meq/g and ~ -43 kJ/mol for IEC 1.9 meq/g were obtained for this temperature range. SPEEK with IEC 1.9 meq/g exhibited higher permeation and selectivity than IEC 1.6 meq/g. This is due to the increased presence of the sulphonic acid groups that are known to improve the performance of any membrane. Water vapour and gas permeation properties of 6FDA – TMPD from 25 – 150 °C were investigated. The water sorption properties from 25 – 35 °C were also investigated and resulting sorption parameters used to model water permeability at the same temperature range. It was found that the infinitely dilute Fickian diffusion constant is temperature – dependant probably due to water sorbed in the polymer plasticizing the membrane and forming clusters at higher water activities and temperatures. A similar permeability trend to SPEEK was obtained where water vapour, CO2 and N2 permeability increased with temperature up to 50 °C but decreased above this. This was likely due to a significant reduction in solubility as temperature increases. It might also be influenced by the formation of clusters that hinder diffusion. Similar results for this polymer were reported by others with “anti – plasticization” or clustering behaviour observed in other polymers. It is also well known that the presence of water reduces the glass transition temperature. It appears that 6FDA – TMPD transitions from a glassy to a rubber state at a Tg of ~ 55 °C. Furthermore, CO2 and N2 permeabilities decrease with increasing feed water activity which suggests the competitive sorption of water. These competitive sorption and plasticization effects were investigated further at high temperatures by comparing water permeability data from a H2O/CO2 feed mixture to that from a H2O/N2 feed mixture. It was found that at low temperatures, the competitive sorption of water reduces sorption of both CO2 and N2. This results in similar water permeabilities through the membrane for both gas mixtures. However as temperature increases the sorption of water is reduced, resulting in increased water permeability for H2O/CO2 feed mixture. This is due to the increased sorption of CO2 and consequently increased CO2 plasticization effects. The permeance data for water and CO2 at 150 °C were compared for all five polymers. The highest H2O/CO2 selectivity was for Nafion 115 followed by Fumapem F - 920, Fumapem E - 540 - GF and Fumapem E - 630 with 6FDA – TMPD having the lowest selectivity. The permeance data was modelled within Aspen HYSYS and it was found that a permeate stream with pH 5.67 is achievable with Nafion 115 at 150 °C. However, the membrane areas required for this are very large indicating that there exists a trade – off between permeate purity and membrane area. A high purity product is required for reuse in the process therefore pH adjustment of the recovered stream would be needed regardless of the membrane material used.
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ItemRheological behavior of alkali-activated slag( 2014)Portland cement based concretes are the most used construction materials worldwide. However, in recent years some new systems have been developed to reduce the cement content of concrete by replacement of cement with other materials, or even introduction of cement-free concretes. This has been motivated by the high energy consumption of Portland cement production, landscape alteration, and high greenhouse gas emissions. Any cement-replacement material must provide satisfactory mechanical properties, durability, and rheological properties. One such option is alkali-activated slag (AAS), which has shown comparable performance while offering major reductions in CO2 emissions compared to Portland cement. However, AAS provides some processing challenges regarding its rheological properties, and the workability is considerably lower at the same water to solids mass ratio compared to Portland cement. Also, water reducing admixtures which are normally used in Portland cement appear to have little or no plasticizing performance in AAS. This investigation focuses primarily on the interrelationship between rheological behavior and AAS chemistry. High pH and electrolyte concentration due to addition of alkali activators affect reaction rate and particle surface charges, which increase interparticle forces, causing yield stress and apparent viscosity changes. Understanding of this chemical environment has resulted in the design of effective polycarboxylate ethers (PCE) as plasticizers for AAS. This was achieved by manipulation of molecular structure of different PCEs and analysis of the plasticizing performance of each synthesized polymer in AAS paste yield stress reduction. In addition to chemistry, the physical properties of precursors are also able to affect rheological behavior. For example, particle size distribution (PSD) has been shown to have a considerable impact on yield stress. A broader particle size distribution provides a higher packing density of particles which reduces the water volume required to fill the voids. The excess water is then used to disperse particles and reduces inter-particle forces, hence yield stress. A very low yield stress can be approached if the PSD is broad enough, in the absence of any rheology-modifying admixtures. Here, a model is proposed to predict the yield stress of blended cement systems with slag and fly ash from particle size distribution data. Although the time-resolved yield stress measurement of a reacting AAS system is of great practical importance, current rheometry methods have limitations in continuous yield stress measurement of an evolving binder because of the conflict between structural network bond formation at rest and disruption of structure formation by shear. Here, an effective method of measuring time-resolved yield stress is developed based on a creeping sphere geometry by minimizing any effects due to residual shear forces. The force required to pull a solid sphere at a very low velocity is used to calculate yield stress using analytical solutions for local flow of a creeping sphere in yield stress materials. The method presented here is capable of measuring time-dependent yield stress changes in reacting or evolving materials for a long time period in a single run, without interfering with ongoing structural network bond formation.
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ItemAn all-diamond hermetic encapsulation for a high-acuity retinal prosthesis( 2014)Bionic vision through electrical stimulation of the retina is fast becoming a reality. To date, clinical trials have allowed blind patients to see a lover’s smile and navigate night scenes. (K Stingl et al, 2013) This kind of data has encouraged an abundance of research activity. Bionic Vision Australia, among others, is developing a retinal prosthesis to restore high visual acuity. One of its flagship technologies is a diamond electrode array, which will form part of the encapsulation for the implanted electronics. The remainder of the encapsulation also needs to be constructed from leak-proof, or hermetic, materials. The aim of this work was to design and test feasibility of a hermetic encapsulation that incorporated the diamond electrode array. An all-diamond hermetic encapsulation design was proposed, in which a diamond box-shaped capsule was bonded to the diamond array, with the electronics contained inside. Diamond capsules were made from polycrystalline diamond. Laser micromachining was found to be the optimal fabrication method. Hermetic joints were made in diamond using vacuum brazing with precious metal braze alloys. Several brazes were investigated for their ability to wet and form strong bonds with diamond. Bond interfaces were studied for morphology, chemical composition and hermeticity. Brazed diamond capsules were sealed at room temperature using laser microwelding. Welds were optimised for smooth surface morphology and hermeticity. The results demonstrated a hermetic all-diamond encapsulation. Combining the hermetic capsule, the brazing technique, and the welding technique with the diamond electrode array formed a retinal prosthesis technology that can protect against degradation for the lifetime of the patient.
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ItemRapid, facile and automated polymer assembly techniques for the preparation of layer-by-layer capsules( 2014)Layer-by-layer (LbL) assembled films and capsules have shown potential application in diverse fields such as energy and drug delivery, because they can be prepared from various polymers and loaded with numerous materials. Although film deposition on planar substrates can be rapid and facile using techniques such as spray-coating or spin-coating, the layering of particles generally requires longer and more involved protocols. LbL assembly on particles typically uses random diffusion as the adsorption driving force, which can lead to the risk of aggregation during layering and washing. To overcome the inherent challenges surrounding polymer deposition on particulate matter, immobilization techniques for suspending the template particles were developed. Immobilizing the template particles has allowed for rapid, facile, and automated layering methods to be applied to particles of varying sizes and compositions. Large particles were suspended in a liquid-based fluidized bed for layering, while smaller particles required immobilization in a porous hydrogel before facile layering was possible. The use of a fluidized bed allowed for the large scale production of polymer microcapsules at a rate roughly ten times faster than conventional methods. However, this technique was generally limited to particles above 5 micrometers. For the hydrogel immobilized particles, a naturally derived polysaccharide, agarose, was used as an immobilizing agent. Electrophoresis, convection and diffusion were then used to deposit polymers on immobilized particles and form capsules ranging from below 100 nanometers to above 1 micrometer. These driving forces allow for the use of different polymer combinations, can be used to load various types of cargo, and can be used to form polymer replica particles. Each driving force has unique benefits, and all three driving forces are either already automated, or potentially automatable. The speed, ease, scope and scale with which these capsules can now be produced should benefit research and development directed towards the application of LbL capsules.
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ItemCharacterisation of buffalo milk, yoghurt and cheese( 2014)Buffalo provide the second largest source of milk in the world after bovine animals. Knowledge and past research on buffalo milk and its product properties, however, is limited, particularly research relevant to Australian manufacturing conditions. This thesis asked four key questions: whether the chemical composition and physicochemical properties of buffalo milk, particularly the microstructure and proteomics of the milk fat globule membrane, significantly differ to bovine milk; whether these differences in milk are translated into the differences in the properties of the resulting yoghurt and cheese products; how to improve the quality of buffalo products; and how the properties of the buffalo cheese change over storage time and vary when produced by different producers. Techniques employed in this thesis included: confocal laser scanning microscopy (CLSM) and cryo-scanning electron microscopy (cryo-SEM) for microstructural investigation, controlled-strain and controlled-stress rheometers for rheological examination, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) for mass and protein identification. Other techniques such as the inductively coupled plasma atomic emission spectroscopy (ICP-OES), high performance liquid chromatography (HPLC), light scattering and colorimetric methods were also used for the characterisation of chemical composition and physicochemical properties of buffalo milk and buffalo milk products under conditions relevant to an Australian manufacturing setting. This work showed that Australian buffalo milk had a richer composition than Australian bovine milk, including a higher concentration of fat, protein, total solids and calcium, consistent with other international studies. High performance liquid chromatography analysis showed that the organic acid profile was significantly different between the two milk types, with a lower concentration of orotic and uric acids in buffalo milk of particular note. Buffalo milk had larger fat globules with a broader size distribution. Confocal laser scanning microscopy observation showed a heterogeneous distribution of phospholipids with the occurrence of non-fluorescent domains that were hypothesized to be rich in sphingomyelin. These domains had various sizes and shapes at room temperature. The domains became larger and more irregular at 4oC and were smaller and more circular at 40oC or 60oC. Using a combination of both in gel digestion and in solution digestion methods, followed by liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) analysis, 184 proteins were identified within the buffalo milk fat globule membrane. This is the largest profile of buffalo milk fat globule membrane proteomics to date. Further quantitative comparisons revealed that the buffalo milk fat globule membrane contained more xanthine dehydrogenase, platelet glycoprotein 4, heat shock cognate and cacineurin B homologous protein but less lactadherin and polymeric immunoglobulin receptor than the bovine counterpart. These differences in the properties of the two milk types affect the processing required during manufacturing and properties of the resulting products. The production of buffalo yoghurt does not require the addition of milk powder or thickener, as occurs for bovine yoghurt, due to the initial higher total solids content of buffalo milk. Yoghurt produced from buffalo milk, however, exhibited a significantly higher level of syneresis (17-20% w/w vs. 1-3% w/w) and poorer rheological properties compared to bovine yoghurt. Buffalo yoghurt was more susceptible to deformation and less able to recover the original network structure after deformation. These properties could be linked to the porous microstructure consisting of large fat globules that tended to disrupt the protein network. An optimisation of the process parameters was therefore performed to improve the quality of buffalo yoghurt, especially to reduce the syneresis. This optimisation initially considered the effect of varying fermentation temperature. Buffalo yoghurt was fermented at three different temperatures: 37oC, 40oC and 43oC. Buffalo yoghurt fermented at 37oC or 40oC required a longer fermentation and gelation time than at 43oC but exhibited a less porous microstructure with reduced syneresis (from 17-20% w/w to 14-16% w/w). The storage modulus was higher at lower temperatures but other rheological properties including the thixotropy, flow behaviour index and consistent coefficient were not improved by decreasing the fermentation temperature. The limited improvement in syneresis and rheological properties of buffalo yoghurt at different fermentation temperatures indicated that further optimisation of buffalo yoghurt production was required. Homogenisation has been reported to improve the quality of bovine yoghurt, including syneresis, texture and rheological properties. The effect of homogenisation on the properties of buffalo yoghurt, however, has not been explored systematically, despite the significantly higher fat content and larger fat globules in buffalo milk. In this experiment, buffalo yoghurt was produced from either milk homogenised at 80 bar or 160 bar. It was shown that homogenised buffalo yoghurt exhibited an improved microstructure consisting of a highly interconnected protein network with thick protein strands and small embedded fat globules. These structural changes resulted in a significant decrease in syneresis and thixotropy and led to a considerable increase in the storage modulus, gel firmness and flow behavior index. While both homogenisation pressures were effective, a higher homogenisation pressure of 160 bar resulted in a lower gel firmness and storage modulus, possibly due to the presence of bigger fat-protein clusters within the milk. These results suggest that a homogenisation pressure of 80 bar could be optimal for improving the quality of buffalo yoghurt and reducing syneresis. Traditional or high moisture buffalo Mozzarella cheese has long been produced but most of the studies in the literature to date have focused on low moisture bovine Mozzarella cheese. In this project, the microstructure and functional properties of laboratory prepared and commercially purchased high moisture buffalo Mozzarella cheeses were studied and compared to commercially purchased high moisture bovine Mozzarella cheeses. Laboratory cheeses were produced at an average yield of approximately 19% and the quality was stable during seven days at cold storage. The whey collected during buffalo cheese production was rich in calcium, lactose and contained an unidentified trisaccharide. Buffalo and bovine Mozzarella cheeses obtained from different producers were found to be significantly different in their chemical composition, organic acid profile and microstructure but had similar hardness and meltability. The buffalo cheeses exhibited a significantly higher ratio of fat/protein and larger fat patches with a less dense protein network within the microstructure compared to the bovine cheeses. These results reflect the effects of processing conditions and the milk types employed by different producers on the resulting cheese properties. They also demonstrate the potential application of buffalo cheese whey as a good source of prebiotics, sugars and minerals. These differences in the microstructure and chemical composition could also be used to identify the milk species of origin in commercial cheese products. In summary, buffalo milk exhibited significant differences from bovine milk, which in turn affected the properties of yoghurt and cheese. Buffalo yoghurt, prepared using the current industrial standard approach, exhibited a high degree of syneresis, a porous microstructure and poorer rheological properties than bovine yoghurt. Lowering the fermentation temperature and the utilisation of homogenisation lowered the syneresis and improved the microstructure and rheological properties of buffalo yoghurt. Buffalo Mozzarella cheese showed large variations and significant differences in microstructure and physicochemical properties compared to bovine Mozzarella cheeses. These results answer the four key questions posed in this thesis. The results presented are useful for buffalo farmers and manufacturers seeking to better understand and control buffalo milk quality and the properties of milk products, as well as the broader community of dairy researchers.