A Note On the Statistical Difference of Small Direct Products

We demonstrate that if two probability distributions D and E of sufficiently small min-entropy have statistical difference ε, then the direct-product distributions D^l and E^l have statistical difference at least roughly ε\s√l, provided that l is sufficiently small, smaller than roughly ε^{4/3}. Previously known bounds did not work for few repetitions l, requiring l>ε^2.

Processing of Synthetic Aperture Radar Images by a Multiscale Boundary Contour System and Feature Contour System

An improved Boundary Contour System (BCS) and Feature Contour System (FCS) neural network model of preattentive vision is applied to large images containing range data gathered by a synthetic aperture radar (SAR) sensor. The goal of processing is to make structures such as motor vehicles, roads, or buildings more salient and more interpretable to human observers than they are in the original imagery. Early processing by shunting center-surround networks compresses signal dynamic range and performs local contrast enhancement. Subsequent processing by filters sensitive to oriented contrast, including short-range competition and long-range cooperation, segments the image into regions. The segmentation is performed by three "copies" of the BCS and FCS, of small, medium, and large scales, wherein the "short-range" and "long-range" interactions within each scale occur over smaller or larger distances, corresponding to the size of the early filters of each scale. A diffusive filling-in operation within the segmented regions at each scale produces coherent surface representations. The combination of BCS and FCS helps to locate and enhance structure over regions of many pixels, without the resulting blur characteristic of approaches based on low spatial frequency filtering alone.

Processing of Synthetic Aperture Radar Images by the Boundary Contour System and Feature Contour System

An improved Boundary Contour System (BCS) and Feature Contour System (FCS) neural network model of preattentive vision is applied to two large images containing range data gathered by a synthetic aperture radar (SAR) sensor. The goal of processing is to make structures such as motor vehicles, roads, or buildings more salient and more interpretable to human observers than they are in the original imagery. Early processing by shunting center-surround networks compresses signal dynamic range and performs local contrast enhancement. Subsequent processing by filters sensitive to oriented contrast, including short-range competition and long-range cooperation, segments the image into regions. Finally, a diffusive filling-in operation within the segmented regions produces coherent visible structures. The combination of BCS and FCS helps to locate and enhance structure over regions of many pixels, without the resulting blur characteristic of approaches based on low spatial frequency filtering alone.

Mathematical modelling and optimisation of the formulation and manufacture of aggregate food products

In this PhD study, mathematical modelling and optimisation of granola production has been carried out. Granola is an aggregated food product used in breakfast cereals and cereal bars. It is a baked crispy food product typically incorporating oats, other cereals and nuts bound together with a binder, such as honey, water and oil, to form a structured unit aggregate. In this work, the design and operation of two parallel processes to produce aggregate granola products were incorporated: i) a high shear mixing granulation stage (in a designated granulator) followed by drying/toasting in an oven. ii) a continuous fluidised bed followed by drying/toasting in an oven. In addition, the particle breakage of granola during pneumatic conveying produced by both a high shear granulator (HSG) and fluidised bed granulator (FBG) process were examined. Products were pneumatically conveyed in a purpose built conveying rig designed to mimic product conveying and packaging. Three different conveying rig configurations were employed; a straight pipe, a rig consisting two 45° bends and one with 90° bend. It was observed that the least amount of breakage occurred in the straight pipe while the most breakage occurred at 90° bend pipe. Moreover, lower levels of breakage were observed in two 45° bend pipe than the 90° bend vi pipe configuration. In general, increasing the impact angle increases the degree of breakage. Additionally for the granules produced in the HSG, those produced at 300 rpm have the lowest breakage rates while the granules produced at 150 rpm have the highest breakage rates. This effect clearly the importance of shear history (during granule production) on breakage rates during subsequent processing. In terms of the FBG there was no single operating parameter that was deemed to have a significant effect on breakage during subsequent conveying. A population balance model was developed to analyse the particle breakage occurring during pneumatic conveying. The population balance equations that govern this breakage process are solved using discretization. The Markov chain method was used for the solution of PBEs for this process. This study found that increasing the air velocity (by increasing the air pressure to the rig), results in increased breakage among granola aggregates. Furthermore, the analysis carried out in this work provides that a greater degree of breakage of granola aggregates occur in line with an increase in bend angle.

Synthetic and mechanistic aspects of the reactions of α-diazosulfoxides

The research described in this thesis focuses, principally, on synthesis of stable α-diazosulfoxides and investigation of their reactivity under various reaction conditions (transition-metal catalysed, photochemical, thermal and microwave) with a particular emphasis on the reactive intermediates and mechanistic aspects of the reaction pathways involved. In agreement with previous studies carried out on these compounds, the key reaction pathway of α-diazosulfoxides was found to be hetero-Wolff rearrangement to give α-oxosulfine intermediates. However, a competing reaction pathway involving oxygen migration from sulfur to oxygen was also observed. Critically, isomerisation of α-oxosulfine stereoisomers was observed directly by 1H NMR spectroscopy in this work and this observation accounts for the stereochemical outcomes of the various cycloaddition reactions, whether carried out with in situ trapping or with preformed solutions of sulfines. Furthermore, matrix isolation experiments have shown that electrocyclisation of α-oxosulfines to oxathiiranes takes place and this verifies the proposed mechanisms for enol and disulfide formation. The introductory chapter includes a brief literature review of the synthesis and reactivity of α-diazosulfoxides prior to the commencement of research in this field by the Maguire group. The Wolff rearrangement is also discussed and the characteristic reactions of a number of reactive intermediates (sulfines, sulfenes and oxathiiranes) are outlined. The use of microwave-assisted organic synthesis is also examined, specifically, in the context of α-diazocarbonyl compounds as substrates. The second chapter describes the synthesis of stable monocyclic and bicyclic lactone derivatives of α-diazosulfoxides from sulfide precursors according to established experimental procedures. Approaches to precursors of ketone and sulfimide derivatives of α-diazosulfoxides are also described. The third chapter examines the reactivity of α-diazosulfoxides under thermal, microwave, rhodium(II)-catalysed and photochemical conditions. Comparison of the results obtained under thermal and microwave conditions indicates that there was no evidence for any effect, other than thermal, induced by microwave irradiation. The results of catalyst studies involving several rhodium(II) carboxylate and rhodium(II) carboxamidate catalysts are outlined. Under photochemical conditions, sulfur extrusion is a significant reaction pathway while under thermal or transition metal catalysed conditions, oxygen extrusion is observed. One of the most important observations in this work was the direct spectroscopic observation (by 1H NMR) of interconversion of the E and Z-oxosulfines. Trapping of the α-oxosulfine intermediates as cycloadducts by reaction with 2,3-dimethyl-1,3-butadiene proved useful both synthetically and mechanistically. As the stereochemistry of the α-oxosulfine is retained in the cycloadducts, this provided an ideal method for characterisation of this key feature. In the case of one α-oxosulfine, a novel [2+2] cycloaddition was observed. Preliminary experiments to investigate the reactivity of an α-diazosulfone under rhodium(II) catalysis and microwave irradiation are also described. The fourth chapter describes matrix isolation experiments which were carried out in Rühr Universität, Bochum in collaboration with Prof. Wolfram Sander. These experiments provide direct spectroscopic evidence of an α-oxosulfine intermediate formed by hetero-Wolff rearrangement of an α-diazosulfoxide and subsequent cyclisation of the sulfine to an oxathiirane was also observed. Furthermore, it was possible to identify which stereoisomer of the α-oxosulfine was present in the matrix. A preliminary laser flash photolysis experiment is also discussed. The experimental details, including all spectral and analytical data, are reported at the end of each chapter. The structural interpretation of 1H NMR spectra of the cycloadducts, described in Chapter 3, is discussed in Appendix I.

Mammalian cell cultures as a model system for the determination of cytotoxicity induced by cholesterol oxidation products

Oxysterols are products of cholesterol oxidation, which may be produced endogenously or may be absorbed from the diet where they are commonly found in foods of animal origin. Oxysterols are known to be cyctotoxic to cells in culture and mode of toxicity has been identified as apoptosis in certain cell lines. The cytotoxicity of the oxysterols 25-hydroxycholesterol (25-OH) and 7β-hydroxycholesterol (7β-OH) was examined in two human cell lines, HepG2, a hepatoma cell line, and U937, a monocytic cell line. Both 25-OH and 7β-OH were cytotoxic to the HepG2 cell line but apoptotic cells were not detected and it was concluded that cells underwent necrosis. 25-OH was not cytotoxic to the U937 cell line but it was found to have a cytostatic effect. 7β-OH was shown to induce apoptosis in the U937 line. The mechanism of oxysterol-induced apoptosis has not yet been fully elucidated, however the generation of an oxidative stress and the depletion of glutathione have been associated with the initial stages of the apoptotic process. The concentration of cellular antioxidant enzyme, superoxide dismutase (SOD) was increased in association with 7β-OH induced apoptosis in the U937 cell line. There was no change in the glutathione concentration or the SOD activity of HepG2 cells, which underwent necrosis in the presence of 7β-OH. Many apoptotic pathways center on the activation of caspase-3, which is the key executioner protease of apoptosis. Caspase-3 activity was also shown to increase in association with 7β-OH-induced apoptosis in U937 cells but there was no significant increase in caspase-3 activity in HepG2 cells. DNA fragmentation is regarded as the biochemical hallmark of apoptosis, therefore the comet assay as a measure of DNA fragmentation was assessed as a measure of apoptosis. The level of DNA fragmentation induced by 7β-OH, as measured using the comet assay, was similar for both cell lines. Therefore, it was concluded that the comet assay could not be used to distinguish between 7β-OH-induced apoptosis in U937 cells and 7β-OH-induced necrosis in HepG2 cells. The cytotoxicity and apoptotic potency of oxysterols 25-OH, 7β-OH, cholesterol- 5a,6a-epoxide (a-epoxide), cholesterol-5β,6β-epoxide (β-epoxide), 19-hydroxy-cholesterol (19-OH), and 7-ketocholesterol (7-keto) was compared in the U937 cell line. 7 β-OH, β-epoxide and 7-keto were found to induce apoptosis in U937 cells. 7β-OH-induced apoptosis was associated with a decrease in the cellular glutathione concentration and an increase in SOD activity, 7-keto and β-epoxide did not affect the glutathione concentration or the SOD activity of the cells.a-Epoxide, 19-OH and 25-OH were not cytotoxic to the U937 cell line.

Chemistry of B1- and B10- boranes containing halogen or pseudohalogen groups

The research described in this thesis involved the chemistry of borane-species which contain one or more halide or pseudohalide groups. Both monoboron species e.g. [BH3X]- and "cluster" borane species e.g. [B10H9X]2- and I-Se B11H10 were studied. The first chapter is a review of the syntheses, properties and reactions of halide and pseudohalide species containing from one to ten boron atoms. Chapter Two is a theoretical investigation of' the electronic and molecular structures of two series of boranes i. e. [BH3X]- and [B10H9X]2- where X = H, CI, CN, NCS, SCN and N3. The calculational method used was the Modified Neglect of Differential Overlap (MNDO) method of Dewar et al. The results were compared where possible with experimental results such as the X-ray crystallographically determined structures of [BH3CI]- and [B10H10]2-. Chapter Three concerns halogenated selenaborane clusters and reports an improved synthesis of 12-Br-SeB11H10 and the first structural data for a simple non-metal containing selenaborane cage with the X-ray crystallographically determined structure of 12-1-SeB11H10. Finally, an indepth n.m.r. study of Se2B9H9 is also reported together with attempts to halogenate this compound. The last two chapters are based on single boron systems. Chapter Four concerns the synthetic routes to amine-boranes and -cyanoboranes from [BH4]- and [BH3CN]- substrates. This chapter discusses some difficulties encountered when polyamines were used in these reactions. The characterisation of an unusual ketone isolated from some of these reactions, the X-ray crystallographically determined structure of 4-dimethylamino-pyridine-cyanoborane and a new route to pyrazabole dimeric species are also discussed. The final chapter reports on work carried out at producing BH2X (X = H, CN) adducts of aminophosphines. Three routes were attempted to generate P-B and N-B bonded species with varying degrees of success. Some unusual products of these reactions are discussed including [Ph2(O) PPPh2 ] [Ph2NH]2, the structure of which was determined by X-ray crystallography.

Synthetic and stereochemical aspects of intramolecular reactions of α-diazoketones catalysed by rhodium(II) carboxylates

Chapter 1 of this thesis is a brief introduction to the preparation and reactions of α-diazocarbonyl compounds, with particular emphasis on the areas relating to the research undertaken: C-H insertion, addition to aromatics, and oxonium ylide generation and rearrangement. A short summary of catalyst development illustrates the importance of rhodium(II)carboxylates for α-diazocarbonyl decomposition. Chapter 2 describes intramolecular C-H insertion reactions of α-diazo-β-keto sulphones to form substituted cyclopentanones. Rhodium(II) carboxylates derived from homochiral carboxylic acids were used as catalysts in these reactions and enantioselection achieved through their use is discussed. Chapter 3 describes intramolecular Buchner cyclisation of aryl diazoketones with emphasis on the stereochemical aspects of the cyclisation and subsequent reaction of the bicyclo[5.3.0]decatrienones produced. The partial asymmetric synthesis achieved through use of chiral rhodium(II) carboxylates as catalysts is discussed. The application of the intramolecular Buchner reaction to the synthesis of hydroazulene lactones is illustrated. Chapter 4 demonstrates oxonium ylide formation and rearrangement in the decomposition of an α-diazoketone. The consequences of the use of chiral rhodium(II) carboxylates as catalysts are described. Particularly significant was the discovery that rhodium(II) (S)-mandelate acts as a very efficient catalyst for α-diazoketone decompositions, in general. Moderate asymmetric induction was possible in the decomposition of α-diazoketones with chiral rhodium(II) carboxylates, with rhodium(II) (S)-mandelate being one of the more enantioselective catalysts investigated. However, the asymmetric induction obtained was very dependent on the exact structure of the α-diazoketone, the catalyst, and the nature of the reaction. Chapter 5 contains the experimental details, and the spectral and analytical data for all new compounds reported.

Biodiscovery of natural products from microbes associated with Irish coastal sponges

Marine sponges have been an abundant source of new metabolites in recent years. The symbiotic association between the bacteria and the sponge has enabled scientists to access the bacterial diversity present within the bacterial/sponge ecosystem. This study has focussed on accessing the bacterial diversity in two Irish coastal marine sponges, namely Amphilectus fucorum and Eurypon major. A novel species from the genus Aquimarina has been isolated from the sponge Amphilectus fucorum. The study has also resulted in the identification of an α–Proteobacteria, Pseudovibrio sp. as a potential producer of antibiotics. Thus a targeted based approach to specifically cultivate Pseudovibrio sp. may prove useful for the development of new metabolites from this particular genus. Bacterial isolates from the marine sponge Haliclona simulans were screened for anti–fungal activity and one isolate namely Streptomyces sp. SM8 displayed activity against all five fungal strains tested. The strain was also tested for anti–bacterial activity and it showed activity against both against B. subtilis and P. aeruginosa. Hence a combinatorial approach involving both biochemical and genomic approaches were employed in an attempt to identify the bioactive compounds with these activities which were being produced by this strain. Culture broths from Streptomyces sp. SM8 were extracted and purified by various techniques such as reverse–phase HPLC, MPLC and ash chromatography. Anti–bacterial activity was observed in a fraction which contained a hydroxylated saturated fatty acid and also another compound with a m/z 227 but further structural elucidation of these compounds proved unsuccessful. The anti–fungal fractions from SM8 were shown to contain antimycin–like compounds, with some of these compounds having different retention times from that of an antimycin standard. A high–throughput assay was developed to screen for novel calcineurin inhibitors using yeast as a model system and three putative bacterial extracts were found to be positive using this screen. One of these extracts from SM8 was subsequently analysed using NMR and the calcineurin inhibition activity was con rmed to belong to a butenolide type compound. A H. simulans metagenomic library was also screened using the novel calcineurin inhibitor high–throughput assay system and eight clones displaying putative calcineurin inhibitory activity were detected. The clone which displayed the best inhibitory activity was subsequently sequenced and following the use of other genetic based approaches it became clear that the inhibition was being caused by a hypothetical protein with similarity to a hypothetical Na+/Ca2+ exchanger protein. The Streptomyces sp. SM8 genome was sequenced from a fragment library using Roche 454 pyrosequencing technology to identify potential secondary metabolism clusters. The draft genome was annotated by IMG/ER using the Prodigal pipeline. The Whole Genome Shotgun project has been deposited at DDBJ/EMBL/GenBank under the accession AMPN00000000. The genome contains genes which appear to encode for several polyketide synthases (PKS), non–ribosomal peptide synthetases (NRPS), terpene and siderophore biosynthesis and ribosomal peptides. Transcriptional analyses led to the identification of three hybrid clusters of which one is predicted to be involved in the synthesis of antimycin, while the functions of the others are as yet unknown. Two NRPS clusters were also identified, of which one may be involved in gramicidin biosynthesis and the function of the other is unknown. A Streptomyces sp. SM8 NRPS antC gene knockout was constructed and extracts from the strain were shown to possess a mild anti–fungal activity when compared to the SM8 wild–type. Subsequent LCMS analysis of antC mutant extracts confirmed the absence of the antimycin in the extract proving that the observed anti–fungal activity may involve metabolite(s) other than antimycin. Anti–bacterial activity in the antC gene knockout strain against P. aeruginosa was reduced when compared to the SM8 wild–type indicating that antimycin may be contributing to the observed anti–bacterial activity in addition to the metabolite(s) already identified during the chemical analyses. This is the first report of antimycins exhibiting anti–bacterial activity against P. aeruginosa. One of the hybrid clusters potentially involved in secondary metabolism in SM8 that displayed high and consistent levels of gene–expression in RNA studies was analysed in an attempt to identify the metabolite being produced by the pathway. A number of unusual features were observed following bioinformatics analysis of the gene sequence of the cluster, including a formylation domain within the NRPS cluster which may add a formyl group to the growing chain. Another unusual feature is the lack of AT domains on two of the PKS modules. Other unusual features observed in this cluster is the lack of a KR domain in module 3 of the cluster and an aminotransferase domain in module 4 for which no clear role has been hypothesised.

Cereal products for specific dietary requirements. Evaluation and improvement of technological and nutritional properties of gluten free raw materials and end products

Coeliac disease is one of the most common food intolerances worldwide and at present the gluten free diet remains the only suitable treatment. A market overview conducted as part of this thesis on nutritional and sensory quality of commercially available gluten free breads and pasta showed that improvements are necessary. Many products show strong off-flavors, poor mouthfeel and reduced shelf-life. Since the life-long avoidance of the cereal protein gluten means a major change to the diet, it is important to also consider the nutritional value of products intending to replace staple foods such as bread or pasta. This thesis addresses this issue by characterising available gluten free cereal and pseudocereal flours to facilitate a better raw material choice. It was observed that especially quinoa, buckwheat and teff are high in essential nutrients, such as protein, minerals and folate. In addition the potential of functional ingredients such as inulin, β-glucan, HPMC and xanthan to improve loaf quality were evaluated. Results show that these ingredients can increase loaf volume and reduce crumb hardness as well as rate of staling but that the effect diverges strongly depending on the bread formulation used. Furthermore, fresh egg pasta formulations based on teff and oat flour were developed. The resulting products were characterised regarding sensory and textural properties as well as in vitro digestibility. Scanning electron and confocal laser scanning microscopy was used throughout the thesis to visualise structural changes occurring during baking and pasta making

Synthesis and reactivity of α-diazo-β-keto sulfoxides: scope and synthetic potential

The research described in this thesis focuses on the design and synthesis of stable α-diazosulfoxides and investigation of their reactivity under a variety of conditions (transition-metal catalysis, thermal, photochemical and microwave) with a particular emphasis on the synthesis of novel heterocyclic compounds with potential biological activity. The exclusive reaction pathway for these α-diazosulfoxides was found to be hetero-Wolff rearrangement to give α-oxosulfine intermediates. In the first chapter, a literature review of sulfines is presented, including a discussion of naturally occurring sulfines, and an overview of the synthesis and reactivity of sulfines. The potential of sulfines in organic synthesis and recent developments in particular are highlighted. The second chapter discusses the synthesis and reactivity of α-diazosulfoxides, building on earlier results in this research group. The synthesis of lactone-based α-diazosulfoxides and, for the first time, ketone-based benzofused and monocyclic α-diazosulfoxides is described. The reactivity of these α-diazosulfoxides is then explored under a variety of conditions, such as transition-metal catalysis, photochemical and microwave, generating labile α-oxosulfine intermediates, which are trapped using amines and dienes, in addition to the spontaneous reaction pathways which occur with α-oxosulfines in the absence of a trap. A new reaction pathway was explored with the lactone based α-oxosulfines, involving reaction with amines to generate novel 3-aminofuran-2(5H)-ones via carbophilic attack, in very good yields. The reactivity of ketone-based α-diazosulfoxides was explored for the first time, and once again, pseudo-Wolff rearrangement to the α-oxosulfines was the exclusive reaction pathway observed. The intermediacy of the α-oxosulfines was confirmed by trapping as cycloadducts, with the stereochemical features dependant on the reaction conditions. In the absence of a diene trap, a number of reaction fates from the α-oxosulfines were observed, including complete sulfinyl extrusion to give indanones, sulfur extrusion to give indanediones, and, to a lesser extent, dimerisation. The indanediones were characterised by trapping as quinoxalines, to enable full characterisation. One of the overriding outcomes of this thesis was the provision of new insights into the behaviour of α-oxosulfines with different transition metal catalysts, and under thermal, microwave and photolysis conditions. A series of 3-aminofuran-2(5H)-ones and benzofused dihydro-2H-thiopyran S-oxides were submitted for anticancer screening at the U.S. National Cancer Institute. A number of these derivatives were identified as hit compounds, with excellent cell growth inhibition. One 3-aminofuran-2(5H)-one derivative has been chosen for further screening. The third chapter details the full experimental procedures, including spectroscopic and analytical data for the compounds prepared during this research. The data for the crystal structures are contained in the attached CD.

Novel ingredients from brewers' spent grain - bioactivity in cell culture model systems and bioactivity retention in fortified food products

Functional food ingredients, with scientifically proven and validated bioactive effects, present an effective means of inferring physiological health benefits to consumers to reduce the risk of certain diseases. The search for novel bioactive compounds for incorporation into functional foods is particularly active, with brewers’ spent grain (BSG, a brewing industry co-product) representing a unique source of potentially bioactive compounds. The DNA protective, antioxidant and immunomodulatory effects of phenolic extracts from both pale (P1 - P4) and black (B1 – B4) BSG were examined. Black BSG extracts significantly (P < 0.05) protected against DNA damage induced by hydrogen peroxide (H2O2) and extracts with the highest total phenolic content (TPC) protected against 3-morpholinosydnonimine hydrochloride (SIN-1)-induced oxidative DNA damage, measured by the comet assay. Cellular antioxidant activity assays were used to measured antioxidant potential in the U937 cell line. Extracts P1 – P3 and B2 - B4 demonstrated significant (P < 0.05) antioxidant activity, measured by the superoxide dismutase (SOD) activity, catalase (CAT) activity and gluatathione (GSH) content assays. Phenolic extracts P2 and P3 from pale BSG possess anti-inflammatory activity measured in concanavalin-A (conA) stimulated Jurkat T cells by an enzyme-linked immunosorbent assay (ELISA); significantly (P < 0.05) reducing production of interleukin-2 (IL-2), interleukin-4 (IL-4, P2 only), interleukin-10 (IL-10) and interferon-γ (IFN-γ). Black BSG phenolic extracts did not exhibit anti-inflammatory effects in vitro. Hydroxycinnamic acids (HA) have previously been shown to be the phenolic acids present at highest concentration in BSG; therefore the HA profile of the phenolic extracts used in this research, the original barley (before brewing) and whole BSG was characterised and quantified using high performance liquid chromatography (HPLC). The concentration of HA present in the samples was in the order of ferulic acid (FA) > p-coumaric acid (p-CA) derivatives > FA derivatives > p-CA > caffeic acid (CA) > CA derivatives. Results suggested that brewing and roasting decreased the HA content. Protein hydrolysates from BSG were also screened for their antioxidant and anti-inflammatory potential. A total of 34 BSG protein samples were tested. Initial analyses of samples A – J found the protein samples did not exert DNA protective effects (except hydrolysate H) or antioxidant effects by the comet and SOD assays, respectively. Samples D, E, F and J selectively reduced IFN-γ production (P < 0.05) in Jurkat T cells, measured using enzyme linked immunosorbent assay (ELISA). Further testing of hydrolysates K – W, including fractionated hydrolysates with molecular weight < 3, < 5 and > 5 kDa, found that higher molecular weight (> 5 kDa) and unfractionated hydrolysates demonstrate greatest anti-inflammatory effects, while fractionated hydrolysates were also shown to have antioxidant activity, by the SOD activity assay. A commercially available yogurt drink (Actimel) and snack-bar and chocolate-drink formulations were fortified with the most bioactive phenolic and protein samples – P2, B2, W, W < 3 kDa, W < 5 kDa, W > 5 kDa. All fortified foods were subjected to a simulated gastrointestinal in vitro digestion procedure and bioactivity retention in the digestates was determined using the comet and ELISA assays. Yogurt fortified with B2 digestate significantly (P < 0.05) protected against H2O2-induced DNA damage in Caco-2 cells. Greatest immunomodulatory activity was demonstrated by the snack-bar formulation, significantly (P < 0.05) reducing IFN-γ production in con-A stimulated Jurkat T cells. Hydrolysate W significantly (P < 0.05) increased the IFN-γ reducing capacity of the snack-bar. Addition of fractionated hydrolysate W < 3 kDa and W < 5 kDa to yogurt also reduced IL-2 production to a greater extent than the unfortified yogurt (P < 0.05).

Characterisation and application of fruit by-products as novel ingredients in gluten-free products

The physicochemical and nutritional properties of two fruit by-products were initially studied. Apple pomace (AP) contained a high level of fibre and pectin. The isolated AP pectin had a high level of methylation which developed viscous pastes. Orange pomace also had high levels of fibre and pectin, and it was an abundant source of minerals such as potassium and magnesium. Due to the fibrous properties of orange pomace flour, proofing and water addition were studied in a bread formulation. When added at levels greater than 6%, the loaf volume decreased. An optimised formulation and proofing time was derived using the optimisation tool; these consisted of 5.5% orange pomace, 94.6% water inclusion and with 49 minutes proofing. These optimised parameters doubled the total dietary fibre content of the bread compared to the original control. Pasting results showed how orange pomace inclusions reduced the final viscosity of the batter, reducing the occurrence of starch gelatinisation. Rheological properties i.e. the storage modulus (G') and complex modulus (G*) increased in the orange pomace batter compared to the control batter. This demonstrates how the orange pomace as an ingredient improved the robustness of the formulation. Sensory panellists scored the orange pomace bread comparably to the control bread. Milled apple pomace was studied as a potential novel ingredient in an extruded snack. Parameters studied included apple pomace addition, die head temperature and screw speed. As screw speed increased the favourable extrudate characteristics such as radical expansion ratio, porosity and specific volume decreased. The inclusion of apple pomace had a negative effect on extrudate characteristics at levels greater than 8% addition. Including apple pomace reduced the hardness and increased the crispiness of the snack. The optimised and validated formulation and extrusion process contained the following parameters: 7.7% apple pomace, 150°C die head temperature and a screw speed of 69 rpm.

Use of oxygen sensors for the non destructive measurement of oxygen in packaged food and beverage products and its impact on product quality and shelf life

The principal objective of this thesis was to investigate the ability of reversible optical O2 sensors to be incorporated into food/beverage packaging systems to continuously monitor O2 levels in a non-destructive manner immediately postpackaging and over time. Residual levels of O2 present in packs can negatively affect product quality and subsequently, product shelf-life, especially for O2-sensitive foods/beverages. Therefore, the ability of O2 sensors to continuously monitor O2 levels present within food/beverage packages was considered commercially relevant in terms of identifying the consequences of residual O2 on product safety and quality over time. Research commenced with the development of a novel range of O2 sensors based on phosphorescent platinum and palladium octaethylporphyrin-ketones (OEPk) in nano-porous high density polyethylene (HDPE), polypropylene (PP) polytetrafluoroethylene (PTFE) polymer supports. Sensors were calibrated over a temperature range of -10°C to +40°C and deemed suitable for food and beverage packaging applications. This sensor technology was used and demonstrated itself effective in determining failures in packaging containment. This was clearly demonstrated in the packaging of cheese string products. The sensor technology was also assessed across a wide range of packaged products; beer, ready-to-eat salad products, bread and convenience-style, muscle-based processed food products. The O2 sensor technology performed extremely well within all packaging systems. The sensor technology adequately detected O2 levels in; beer bottles prior to and following pasteurisation, modified atmosphere (MA) packs of ready-to-eat salad packs as respiration progressed during product storage and MA packs of bread and convenience-style muscle-based products as mycological growth occurred in food packs over time in the presence and absence of ethanol emitters. The use of the technology, in conjunction with standard food quality assessment techniques, showed remarkable usefulness in determining the impact of actual levels of O2 on specific quality attributes. The O2 sensing probe was modified, miniaturised and automated to screen for the determination of total aerobic viable counts (TVC) in several fish species samples. The test showed good correlation with conventional TVC test (ISO:4833:2003), analytical performance and ruggedness with respect to variation of key assay parameters (probe concentration and pipetting volume). Overall, the respirometric fish TVC test was simple to use, possessed a dynamic microbial range (104-107 cfu/g sample), had an accuracy of +/- one log(cfu/g sample) and was rapid. Its ability to assess highly perishable products such as fish for total microbial growth in <12 hr demonstrates commercial potential.

Synthesis and reactivity of pyridine substituted α-diazocarbonyl compounds and exploration of rhodium carboxylates as asymmetric catalysts

The primary objective of this thesis was the preparation of a series of pyridine-containing α-diazocarbonyl compounds and subsequent investigation of the reactivity of these compounds on exposure to transition metal catalysts. In particular, the reactivity of the pyridyl α-diazocarbonyls was compared to that of the analogous phenyl α-diazocarbonyl compounds to ascertain the impact of replacement of the phenyl ring with pyridine. The first chapter initially provides a brief introduction into α-diazocarbonyl chemistry, comprising a compendium of well-established and recently developed methods in the preparation of these compounds, as well as an outline of the reactivity of these versatile substrates. The substantive element of this introductory chapter comprises a detailed review focused on transition metal-catalysed transformations of heterocyclic α-diazocarbonyl compounds, highlighting the extraordinary diversity of reaction products which can be accessed. This review is undertaken to set the work of this thesis in context. The results of this research are discussed in the second and third chapters together with the associated experimental details, including spectroscopic and analytical data obtained in the synthesis of all compounds during this research. The second chapter describes the preparation of a range of novel pyridine-containing α-diazocarbonyl compounds via a number of synthetic strategies including both acylation and diazo transfer methodologies. In contrast to the phenyl analogues, the generation of the pyridine α-diazocarbonyl substrates was complicated by a number of factors including the inherent basicity of the pyridine ring, tautomerism and existence of rotamers. Rhodium- and copper-mediated transformations of the pyridine-containing α-diazocarbonyl compounds is discussed in detail displaying very different reactivity patterns to those seen with the phenyl analogues; oxidation to 2,3- diketones, 1,2-hydride shift to form enones and oxonium and sulfonium ylide formation/rearrangement are prominent in the pyridyl series, with no evidence of aromatic addition to the pyridine ring. The third chapter focuses on exploration of novel chiral rhodium(II) catalysts, developed in the Maguire team, in both intermolecular cyclopropanations and intramolecular C–H insertion reactions. In this chapter, the studies are focused on standard α-diazocarbonyl compounds without heteroaryl substituents. The most notable outcome was the achievement of high enantiopurities for intramolecular C–H insertions, which were competitive with, and even surpassed, established catalyst systems in some cases. This work has provided insight into solvent and temperature effects on yields as well as enantio- and diastereoselectivity, thereby providing guidance for future development and design of chiral rhodium carboxylate catalysts. While this is a preliminary study, the significance of the results lie in the fact that these are the first reactions to give substantial asymmetric induction with these novel rhodium carboxylates. While the majority of the α-diazocarbonyl compounds explored in this work were α-diazoketones, a number of α-diazoesters are also described. Details of chiral stationary phase HPLC analysis, single crystal analysis and 2D NMR experiments are included in the Appendix (Appendix III-V).