Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, December 2006. / Includes bibliographical references (p. 89-94).

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 132-143). Also available on the World Wide Web.

Thesis (M.S.)--Virginia Polytechnic Institute, 1964. / Typewritten. Vita. Abstract at end. Bibliography: leaves 32-34. Also available via the Internet.

Ketonic rancidity is associated with the lauric acid oils and butterfat. It arises when short and intermediate carbon chain length fatty acids (C6 to C14) are converted into methyl ketones (C5 to C13) by certain fungi. Ketonicrancidity will not occur in fats and oils that do not contain these fatty acids. Fermentation experiments with whole oils and simple triglycerides confirmed that only short and intermediate carbon chain length fatty acids were converted into methyl ketones. Methyl ketones produced contained one carbon atom less than the parent fatty acid. Tetradecanoic acid was the longest fatty acid to undergo conversion into its corresponding methyl ketone. Experiments with free fatty acids established that short and intermediate carbon chain length fatty acids inhibited the growth of Penicillium crustosum, Evidence was presented to demonstrate that the mitochondrion was a site of antifungal activity. It was concluded that the conversion of fatty acids into methyl ketones was a detoxification mechanism for their removal from the environment. Extrinsic factors (temperature, pH, aw, preservatives and O2 removal) were used to control fungal growth and ketonic rancidity. Fungal homeostatic mechanisms often enabled P.crustosum to grow under unfavourable environmental conditions. It was suggested that acombination of preservation measures should be used to prevent ketonic rancidity in the lauric acid oils and their products.

Hypertension is a widespread condition which may cause cardiovascular events when left untreated. If high blood pressure (BP) is noticed at all, it is mostly only sub-optimally controlled making nutritional interventions a cost-effective and safe preventive measure and an alternative to medical treatment. Previous studies have shown that increased fibre consumption reduces BP which was particularly effective in hypertensive subjects. Fibres are indigestible and hence are available for fermentation by the colonic microbiota which produces the short chain fatty acids (SCFAs) acetate, propionate and butyrate. Intriguingly, recent studies carried out in mice showed that SCFAs can reduce BP. Therefore, we hypothesised that gut microbiota-derived SCFAs can (1) reduce BP in middle-aged male volunteers and (2) influence the protein expression of BP regulatory systems in a cellular model. As the development of a cellular angiotensin II-induced hypertension model was unsuccessful, the effects of SCFAs on a molecular level were assessed in unstimulated human aortic endothelial cells (HAECs). The expression of proteins involved in the BP regulating renin angiotensin system (RAS) was assessed by western blotting. Additionally, a human supplementation trial is being carried out looking at the acute consumption of a low (0.16 g) and high (2.35 g) propionate dose on BP and other cardiovascular markers in middle-aged male volunteers. In vitro work showed that SCFAs did not affect RAS expression in HAECs. However, acute propionate supplementation influenced BP and its regulation. Preliminary data show, that while a high propionate dose led to increases in plasma propionate by on average 4 µM and acetate levels with concurrent increases in BP, arterial stiffness and plasma renin concentration, a low propionate dose resulted in plasma propionate increases of about 0.5 µM with simultaneous reductions in systolic BP. Taken together, these results suggest that SCFAs play a regulatory role in the homoeostasis of BP.

Fish provides a major source of proteins and polyunsaturated fatty acids which are known to prevent coronary heart diseases. However, inherent characteristics such as colour and texture prevent the effective utilisation of some fish, especially fatty pelagics for human consumption. Instead, they are used for fish oil and fish meal production. For this reason and for enhancing the utilisation of valuable resources, the physico-chemical properties, which may be species specific, were investigated in relation to two Namibian species, namely, horse mackerel (Trachurus capensis) and snoek (Thyrsites atun). The results showed that horse mackerel (Trachurus capensis) and snoek (Thyrsites atun) contain high contents of palmitic acids (29%), oleic acids (25%), and the omega-3-polyunsaturated fatty acids, such as docosahexaenoic acids (DHA) (15%) and eicosapentaenoic acids (EPA) (9%). The studies also showed that optimum protein extractability was obtained with 5% NaCl at pH 7.2 and the highest gel strength at pH 6.5-7.0. CaCO3 had detrimental effect on the water-holding capacity when used above 50mg.l-1 in washing water. Agar and sodium alginate extracted from Namibian Gracilaria verrucosa (red seaweed) and Laminaria schinzii (brown seaweed) respectively, were also characterised for their physico-chemical properties. Both the nontreated and treated agars were observed by colorimetric method to contain low levels of sulphate, an observation also confirmed by NMR and Raman FTIR spectroscopy. Sodium alginate was found to contain high content of guluronic acid (75%) by NMR, a good index of strong gelling ability. The good functionalities obtained as a result of optimising the physicochemical properties of fish proteins and seaweed polysaccharides enabled an investigation of the interactions of the two components. Studies on the interactions of the both horse mackerel and snoek with either sodium alginate or agar were undertaken by rheology, differential scanning calorimetry and phase contrast microscopy. Large deformation and small deformation rheological studies showed a decrease in the gel strength of fish proteins with the addition of either polysaccharide at all combinations. The DSC results indicated a lowering of the denaturation temperature with the addition ratios of increasing amounts of sodium alginate to fish proteins. Although the mixture of fish proteins and agar resulted in the lowering of the denaturation temperature, the shift; was not as pronounced as that obtained with sodium alginate. The reason for the lowering of gel strength and G' values was attributed to phase separation of fish proteins and polysaccharides which was reflected by phase contrast microscopy studies. This investigation has resulted in the characterisation of valuable fish and seaweed polysaccharide resources from Namibia which could be used in combination for the development of new food products.

Part I. Synthetic studies. cis-Hydroxylation of Long-chain Olefins. The Woodward cis-hydroxylation procedure, involving the use of iodine and silver acetate in wet acetic acid, has been adapted and applied to the cis-hydroxylation of long-chain olefins. It is a satisfactory method for oxidising these compounds and has some advantages over other methods of cis-hydroxylation. A further cis-hydroxylation procedure, Involving the use of iodine and silver nitrate in acetonitrile has also been developed. Part II. Degradative Studies. The EPOXY Acid in Cameline Oil. A hydroxy acid, isolated from Camelina sativa seed oil, has been shown to be threo-15:16-dihydroxyoctadec-cis-9cis-12-dienolc acid. Infra-red studies indicate that this acid, is present in the oil as glycerides of cis-l5:16-epoxylinolele acid and Is thus closely related to the only other naturally occurring long-chain epoxy acid viz. cis-12:13-epoxyolelc acid. Part III. Analytical Studies. The Occurrence of 9-hydroxy-octadec-cis-12-enoic Acid in Various Strophanthns Oils. 9-Hydroxyoctadec-12-enoic acid has been identified, qualitatively and quantitatively, in ten Strophanthus oils. In two oils a small amount of optically active erythro-9:10-dihydroxystearic acid accompanies the monohydroxy acid and may occur throughout the genus. The oils have been analysed by throe methods and these are discussed comparatively. The analytical results lead to some generalisations and correlations. Part IV. Configurational Studies. 9-Hydroxyoetadec-cis-12-enoic acid has been isolated and three of the four isomeric 9:12:13-trihydroxystearic acids prepared from it. The rotations of these and other hydroxy acids have been measured. It is tentatively suggested that the 9-hydroxy acid has the D-configuration, thus being in the same series as natural riclnoleic acid. Unsuccessful attempts to synthesise long-chain dihydroxy acids, of known configuration, by extension of the chain of optically active tartaric acid are reported and a more suitable synthetic route is suggested. Part I. Synthetic studies. cis-Hydroxylation of Long-chain Olefins. The Woodward cis-hydroxylation procedure, involving the use of iodine and silver acetate in wet acetic acid, has been adapted and applied to the cis-hydroxylation of long-chain olefins. It is a satisfactory method for oxidising these compounds and has some advantages over other methods of cis-hydroxylation. A further cis-hydroxylation procedure, Involving the use of iodine and silver nitrate in acetonitrile has also been developed. Part II. Degradative Studies. The EPOXY Acid in Cameline Oil. A hydroxy acid, isolated from Camelina sativa seed oil, has been shown to be threo-15:16-dihydroxyoctadec-cis-9cis-12-dienolc acid. Infra-red studies indicate that this acid, is present in the oil as glycerides of cis-l5:16-epoxylinolele acid and Is thus closely related to the only other naturally occurring long-chain epoxy acid viz. cis-12:13-epoxyolelc acid. Part III. Analytical Studies. The Occurrence of 9-hydroxy-octadec-cis-12-enoic Acid in Various Strophanthns Oils. 9-Hydroxyoctadec-12-enoic acid has been identified, qualitatively and quantitatively, in ten Strophanthus oils. In two oils a small amount of optically active erythro-9:10-dihydroxystearic acid accompanies the monohydroxy acid and may occur throughout the genus. The oils have been analysed by throe methods and these are discussed comparatively. The analytical results lead to some generalisations and correlations. Part IV. Configurational Studies. 9-Hydroxyoetadec-cis-12-enoic acid has been isolated and three of the four isomeric 9:12:13-trihydroxystearic acids prepared from it. The rotations of these and other hydroxy acids have been measured. It is tentatively suggested that the 9-hydroxy acid has the D-configuration, thus being in the same series as natural riclnoleic acid. Unsuccessful attempts to synthesise long-chain dihydroxy acids, of known configuration, by extension of the chain of optically active tartaric acid are reported and a more suitable synthetic route is suggested.

The commercial hydrogenation of oils and fats results in the formation of, among other components, geometrical and positional isomers of monounsaturated fatty acids. The view that there may be hazards associated with such oils have occasionally been expressed. Prior to an investigation of the levels of such acids in human tissue and UK dietary fats, the synthesis of a series of these acids, as standards, and their characterisation, was necessary. For the synthetic programme, the general scheme provided a convenient route for the synthesis of geometrical and positional isomers from common precursors. When condensation of the 1-alkyne and a-chloro-w-iodoalkane was performed via sodamide in liquid ammonia, the scheme was limited but was extended somewhat when performed via methyllithium in dioxan. Generally, yields decreased with the increasing chain length, and migration of the unsaturated bond to the extremities of the resulting molecule. Chromatographic separation, both capillary column GLC and reversephase HPLC, was readily achieved on the basis of chain length and configuration of the double bond. Furthermore, the partial separation of positional isomers was achieved. NMR spectroscopy unambiguously determined the configuration and position of unsaturation in virtually every fatty acid. Assignment is based on the fact that functional groups within an acid alter the chemical shift of neighbouring carbons in a characteristic manner. No one of these techniques alone is applicable to the determination of positional isomerism in a complex lipid mixture and must be used in combination. Whereas NMR is undoubtedly invaluable in the quantification of positional isomers on an individual basis, or in profiling simple mixtures, it is not as applicable to the direct analysis of complex lipid samples. Emphasis on the continuing development of capillary column GLC holds the most promise for the direct quantification of positional isomerism.

No description available.