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Collection of the author's previous publications. Includes bibliographies.

Bibliography: leaves 174-192. This research aims to obtain detailed knowledge on the effects of a period of high temperature on the accumulation of grain dry matter and endosperm starch, protein and B-glucan in the developing grain of the malting barley variety Schooner. Bbarley plants are exposed to high temperatures during mid grain filling for 5 days. Grain growth characteristics are measured prior to, during and following the high temperature period, with the aim of characterising the high temperature response in developing grain. The activities of several enzymes and metabolities of the pathway of starch synthesis are monitored and compared to those in grains maintained at a lower temperature. In addition, grain structure is also compared between control and heat treated grain during development, at maturity and following malting.

Thesis (M.Sc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2009.

Starch and microbial exo-polysaccharides produced by prokaryotes (i.e. Eubacteria and Archaebacteria) and eukaryotes (i.e. phytoplankton, fungi, and algae) are recognized as a permanent source of biopolymers for the packaging industry. However, the unsuitable mechanical properties for thermoplastic applications and/or high cost of production have restricted their generalized use. Fungal isolates of the genus Ophiostoma are able to produce exo-polysaccharides or protein-like compounds in a medium containing starch as the substrate. Various analytical techniques were used as an approach to investigate the interaction between starch and the fungal extracellular metabolites and the effect of the molecular-structural modifications on the functional properties of the materials. Native starches were used as control in all experiments. Analyses performed by dynamic mechanical thermal analysis (DMTA), which provides information related to the viscoelastic properties, showed that the storage modulus (E') increased substantially after the modification of the starch showing a process of chain stiffness. The determination of the glass transition temperature (Tg) by tan  and loss modulus (E'') peaks showed various thermal transitions indicating a complex molecular aggregation due to the potential presence of dissimilar amorphous polymers. Experiments performed in DSC confirmed the presence of the various thermal transitions associated to the Tg of these materials. The first derivative of mass loss with respect to temperature during the thermogravimetric (TG) analysis was slightly lower compared with native starches (at ~630 and 650°C). However, modified starches can withstand high temperatures showing residues up to 20% at 1000°C. Studies on the characterization of the flow properties of the polymers by capillary rheology showed in both samples a shear thinning behavior. The double logarithmic plot of the shear rate vs. shear viscosity produced a straight line and in consequence a power law equation was used to describe the rheological behavior ( = K'n). The results showed that in order to achieve the same shear rate (') in both samples (modified and native starches) it is necessary to apply a higher shear stress () in the fungal treated materials. As a result, the consistency power law index (n) decreased and the consistency value increased (K). The practical consequence is that the melting point of these polysaccharides shifted to higher temperatures. By using various analytical techniques (including chromatography, spectroscopy, spectrometry) it was found that these phenomena may be due to the interaction of starch with protein-like or exo-polysaccharides or both which may influence the viscosity, bind adjacent molecules (i.e. network-like) and restrict the molecular motion. Evidences of the presence of pendant groups attached to high molecular weight compounds were also found. This information will give guidance to further structural studies and it is intended to pave the way for a variety of industrial applications.

Starch and microbial exo-polysaccharides produced by prokaryotes (i.e. Eubacteria and Archaebacteria) and eukaryotes (i.e. phytoplankton, fungi, and algae) are recognized as a permanent source of biopolymers for the packaging industry. However, the unsuitable mechanical properties for thermoplastic applications and/or high cost of production have restricted their generalized use. Fungal isolates of the genus Ophiostoma are able to produce exo-polysaccharides or protein-like compounds in a medium containing starch as the substrate. Various analytical techniques were used as an approach to investigate the interaction between starch and the fungal extracellular metabolites and the effect of the molecular-structural modifications on the functional properties of the materials. Native starches were used as control in all experiments. Analyses performed by dynamic mechanical thermal analysis (DMTA), which provides information related to the viscoelastic properties, showed that the storage modulus (E') increased substantially after the modification of the starch showing a process of chain stiffness. The determination of the glass transition temperature (Tg) by tan  and loss modulus (E'') peaks showed various thermal transitions indicating a complex molecular aggregation due to the potential presence of dissimilar amorphous polymers. Experiments performed in DSC confirmed the presence of the various thermal transitions associated to the Tg of these materials. The first derivative of mass loss with respect to temperature during the thermogravimetric (TG) analysis was slightly lower compared with native starches (at ~630 and 650°C). However, modified starches can withstand high temperatures showing residues up to 20% at 1000°C. Studies on the characterization of the flow properties of the polymers by capillary rheology showed in both samples a shear thinning behavior. The double logarithmic plot of the shear rate vs. shear viscosity produced a straight line and in consequence a power law equation was used to describe the rheological behavior ( = K'n). The results showed that in order to achieve the same shear rate (') in both samples (modified and native starches) it is necessary to apply a higher shear stress () in the fungal treated materials. As a result, the consistency power law index (n) decreased and the consistency value increased (K). The practical consequence is that the melting point of these polysaccharides shifted to higher temperatures. By using various analytical techniques (including chromatography, spectroscopy, spectrometry) it was found that these phenomena may be due to the interaction of starch with protein-like or exo-polysaccharides or both which may influence the viscosity, bind adjacent molecules (i.e. network-like) and restrict the molecular motion. Evidences of the presence of pendant groups attached to high molecular weight compounds were also found. This information will give guidance to further structural studies and it is intended to pave the way for a variety of industrial applications.

The nearly unlimited applications and uses of starch for food industry make this natural polymer a unique component; no other constituent can provide consistence and storage stability to such a large variety of foods. Starch can be extracted from agricultural produce through either chemical processes or physical separation. The latter involves the application of centrifugal forces by means of hydrocyclones. A hydrocylcone is a device which separates, through physical methods, two phases of different densities. There are three flows involved: the feed (mixture introduced in the hydrocyclone), the overflow (the least dense part) and the underflow (the densest part). Normally, the underflow part, or commonly known as "heavies", is the desirable part that companies keep, this is, the starch. Despite hydrocyclones are not very expensive devices, current-based hydrocyclones demand high energy rates. This work describes the design and testing of energy-saving hydrocyclones for extracting starch from wheat. Eight prototypes were built and tested at Larsson Mekaniska Verkstad AB (Bromölla, Sweden). This company makes process equipment for the starch industry and was the one with which the author collaborated during the ellaboration of the Degree Project. Six of the eight hydrocyclones were built by Larsson; another was a commercial hydrocyclone and the last one was the one figured out after reading some literature and updates in the hydrocyclones field. The experiments consist of trying the eight hydrocyclones under different conditions, combining concentrations (153 g/L and 237 g/L) and pressures (500 Pa and 700 Pa). The experimental results proved the importance of geometry on hydrocyclone design, and showed the effect of geometrical parameters on the energy-saving properties of cyclones. Four of the eight new models behaved satisfactorily for low energy and high efficiency conditions, obtained with inlet pressures of 500 kPa and starch concentrations of 237 g/L.

<p>The nearly unlimited applications and uses of starch for food industry make this natural polymer a unique component; no other constituent can provide consistence and storage stability to such a large variety of foods. Starch can be extracted from agricultural produce through either chemical processes or physical separation. The latter involves the application of centrifugal forces by means of hydrocyclones. A hydrocylcone is a device which separates, through physical methods, two phases of different densities. There are three flows involved: the feed (mixture introduced in the hydrocyclone), the overflow (the least dense part) and the underflow (the densest part). Normally, the underflow part, or commonly known as "heavies", is the desirable part that companies keep, this is, the starch. Despite hydrocyclones are not very expensive devices, current-based hydrocyclones demand high energy rates. This work describes the design and testing of energy-saving hydrocyclones for extracting starch from wheat. Eight prototypes were built and tested at Larsson Mekaniska Verkstad AB (Bromölla, Sweden). This company makes process equipment for the starch industry and was the one with which the author collaborated during the ellaboration of the Degree Project. Six of the eight hydrocyclones were built by Larsson; another was a commercial hydrocyclone and the last one was the one figured out after reading some literature and updates in the hydrocyclones field. The experiments consist of trying the eight hydrocyclones under different conditions, combining concentrations (153 g/L and 237 g/L) and pressures (500 Pa and 700 Pa). The experimental results proved the importance of geometry on hydrocyclone design, and showed the effect of geometrical parameters on the energy-saving properties of cyclones. Four of the eight new models behaved satisfactorily for low energy and high efficiency conditions, obtained with inlet pressures of 500 kPa and starch concentrations of 237 g/L.</p>

Thesis (Ph. D.)--Institute of Paper Chemistry, 1939. / Bibliography: leaves 75-78.

Starch is an important component of a wheat grain, comprising 50-70% of its dry weight. Its biosynthesis involves a complex pathway mediated by several enzymes, each of which is encoded by genes that have more than one family member. To better understand starch synthesis in wheat grains, this study characterized the sucrose-starch metabolic pathway using physiological, molecular, biochemical and metabolic approaches. These analyses led to the identification of genes that appear to have predominant expression during grain development in wheat including, TaSUT1, TaSuSy2, AGPL1, SSI, SSIIIa and SBEIIa, suggesting that these genes play a regulatory role in starch accumulation. This was further confirmed by comparative analyses of starch synthesis between cultivars with contrasting thousand kernel weights, which revealed a closer association of the expression of the same set of genes with starch accumulation in developing wheat grains. The effect on starch yield of one of the candidate genes identified, AGPase, was examined through a transgenic approach, which involved expression of a gene encoding modified version of maize AGPase large subunit, designated as Sh2r6hs, in wheat under the control of maize’s constitutive Ubiquitin1 promoter. This manipulation of the wheat AGPase activity produced wheat lines with increased AGPase activity, grain weight and grain starch level, suggesting that the wheat grain size can be enhanced through increasing the capacity of starch synthesis both in the source and sink tissues. The study also identified and characterized a partial fragment of wheat rbcS promoter, and indicated that the promoter fragment can potentially be used as a tool for targeting the expression of genes of interest in photosynthetic source tissues. / October 2014