Thesis (Ph.D.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 209-231) Also available in print.

Thesis (Ph. D.)--University of Minnesota, 1922. / Biographical. Bibliography: p. 75-84.

Thesis (Ph. D.)--University of Minnesota, 1928. / Biography. "Literature cited": p. 77-78.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1972. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (doctoral)--Universität Jena. / Includes bibliographical references.

Kishk is a very popular dried fermented milk/cereal mixture consumed in many countries of the world. The manufacture of Kishk is based on traditional methods, and may differ from one region to another. In the present study, the following aspects were investigated: First, standardising the production of laboratory-made Kishk; after using different ratios of wheat Burghol and yoghurt, a ratio of 1:4 was found to be suitable. Second, evaluating the compositional quality of Burghol made from different varieties of oats and barley, and the effect of these cereals on the overall characteristics of Kishk. Third, assessing the quality of Kishk using different cereals (porridge oats, oats flour, wheat flour, Burghol and Burghol flour), yoghurt, acidulant and/or 'milk'. Burghols from different varieties of barley and oats were prepared in a similar manner to that for the production of wheat Burghol. The traditional cracking process was successful for barley and oats, but difficulties were experienced in the separation of husk from the oats product. The chemical composition of the parboiled 'cracked' cereals were compared with that of the original grains, and with wheat Burghol. In all, the proximate composition (i.e. fat, protein and ash) of the parboiled 'cracked' products were reduced compared to the original cereals. Sensory evaluation of these Kishks could be summarised as follows: First, Kishks made with different cereal Burghols (oats, barley or wheat) were differentiated by the type of cereal used. Second, the flavour of Kishk made with different cereals (oats and wheat), yoghurt, GDL and 'milk' were different. Most of the odour, flavour, after-taste and mouth feel characters have differentiated the Kishk according to the type of 'dairy' base used. The perceived mouth feel characters (chalky, sticky, slimy) differentiated the Kishk according to the type and particle size of cereals (e.g. porridge oats, oats flour, wheat Burghol or wheat flour) used. Third, Kishk made with different wheat products (Burghol, Burghol flour or wheat flour) was also differentiated by the particle size. Fourth, wheat flour-based Kishk was perceived to have better mouth feel characters followed by Burghol flour- and Burghol-based Kishk. Yoghurt/Burghol or wheat flour mixtures were studied during the secondary fermentation period (0, 48, 96 and 144 h), and the influence of particle size of the cereal was evident on the β-amylase and proteolytic activities. Burghol-based mixture had the highest β-amylase content/activity and wheat flour the lowest, whilst the non-protein nitrogen compounds content was higher in wheat flour than the Burghol-based mixture after 144 h. The degradation of starch in all these mixtures was almost linear during the secondary fermentation period. This appeared to be influenced by the interactions between the starch and other components such as protein, lipids and polyphenols to make the starch resistant to enzymatic degradation. The release of enzyme inhibitors such as phytic acids during the secondary fermentation period may also have interfered in the recovery of the starch during analysis. The microstructure of cereal (Burghol or wheat flour)/yoghurt or whey from yoghurt mixture suggest that physical change in starch granules occurred rather than degradation.

A lengthy, and at times heated, debate on the regulation of animal numbers has proceeded in the literature for over half a century. A wide variety of causal agents - from sun spots to a shortage of trace elements - has been proposed to explain the observed densities, and a wide variety of mechanisms has also been proposed - from natural selection to chance. Only occasionally have any of these proposals been rigorously tested, and the survival of partially or totally conflicting hypotheses has been correspondingly high. I have attempted to test just one of these proposals: the polymorphism hypothesis of Chitty (Proc. Ecol. Soc. Australia 2:51-78, 1967.) According to this hypothesis, any natural population which lives in a highly favourable habitat can regulate its numbers through the action of two morphs, one characterized by a high fecundity and the other by a superior ability to hold its position in the environment. Population density is postulated to be a function of the relative frequency of the morphs and to change in a predictable way. I have conducted five experiments to investigate the existence of, and the mode of interaction between, these presumed morphs in Tribolium confusum, the questions asked being: 1) Is the density achieved by open populations (i.e. those from which emigration is allowed) different from that in closed populations (i.e. those from which emigration is prevented)? 2) Is the mechanism of regulation in open populations different from that in closed populations? 3) Is the tendency to migrate a constant property of individuals? 4) Is the density achieved by populations founded by migrants different from that of populations founded by non-migrants? 5) Is the density achieved by open populations (with migration by self-selection) different from that achieved by closed populations from which an equal number of animals are removed at random? I found the answers to all these questions to be 'yes', and the differences in each case to be in the direction predicted by the polymorphism hypothesis. I suggest that the polymorphism hypothesis is useful for predicting future densities of populations from which emigration is occurring, but is not useful for predicting densities in populations 1) from which animals cannot escape or 2) in which mortality caused by extrinsic factors is so great that, despite high fecundity, the populations are unable to produce a migrating surplus. I argue that 1) and 2) are rare in nature, or at least have been studied rather seldom. / Science, Faculty of / Zoology, Department of / Graduate

Similarities can be drawn between protein contents, solubility profile, remix loaf volume, and total sulfhydryl-disulfide contents of barley and wheat flours. However, the quantitative relat-ship between loaf volume and protein content or protein solubility distribution used for wheat flour did not apply to barley. Barley flour demonstrated very poor breadmaking ability and low loaf volume. Elution patterns from Sephadex G100 showed that the molecular weight of barley gluten was lower than wheat. Sephadex G150 elution profiles of barley and wheat glutelin gave two and three peaks respectively. The F₂ fraction of wheat glutenin, which differentiates the breadmaking potential of different wheat flours, was missing in barley. Turbidity studies on protein aggregation behavior revealed that barley proteins had a lower aggregation rate than wheat. Wheat gliadin gave the highest rate of aggregation, while hordein failed to aggregate. The alcohol soluble protein fraction of barley was capable of polymerization via disulfide bridges at low temperatures, which resulted in 'gluten' formation in vitro. Such a phenomenon was not observed in wheat. Addition of oxidizing agents did not improve the quality of barley dough. These suggested that the thiol and disulfide groups of barley are either very inaccessible, and/or different from wheat. Therefore, it is postulated that the Theologically effective sulfhydryl and disulfide groups in barley are inferior in quality and quantity than that of wheat. Amino acid analysis demonstrated that proteins of barley and wheat were different in structure and composition. The amount of glutamic acid in barley was only about 70fo that of wheat. Fluorescence quenching studies showed that hydrophobicity of wheat gluten was higher than barley. Barley is weak in the vital chemical forces which govern breadmaking potential, and furthermore there are numerous differences among functional proteins of these two cereals. These studies would provide some insights to their differences in physical properties and breadmaking potentials. / Land and Food Systems, Faculty of / Graduate

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