Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Variation in quantity and quality of gluten proteins is largely responsible for the genotypic differences associated with the dough rheological parameters, maximum resistance (R[subscript]max) and extensibility (Ext.). In the context of bread making, doughs characteristic of good quality have moderate to high extensograph maximum resistance (R[subscript]max) and high extensibility (Ext.). The term usually applied to describe the balance between these two parameters is dough strength. Generally, weak doughs perform poorly in baking tests and as dough strength increases, bread making quality also increases. Important proteins that constitute the 'gluten complex' include high molecular weight glutenin subunits (HMW-GSs) and low molecular weight glutenin subunits (LMW-GSs). These proteins, which interact to produce large polymeric proteins, are coded at the Glu-1 and Glu-3 loci on group 1 chromosomes, respectively. Extensive allelic variation exists a1 each of the G/u-1 and Glu-3 loci. Field trials (4 years) and physical dough quality tests on harvested grain from a set of near-isogenic lines, differing in glutenin composition, were used to investigate the effect of numerous glutenin alleles on dough rheological parameters. Glutenin allele main effects were ranked as follows: Glu-A1 a = p = b > c for R[subscript]max and Glu-A1 a = b = p > C for Ext.; Glu-B1 i ≥ b = c > d = a for R[subscript]max and Glu-B1 a = i = c ≥ b ≥ d for Ext.; Glu-D1d > Glu-D1a = Glu-D1b ≥ Glu-D1f for R[subscript]max and Glu-D1 a = b = f ≥ d for Ext.; Glu-A3 d = b ≥ c = f ≥ a > e for R[subscript]max and Glu-A3 b = a = d = c = f ≥ e for Ext.; Glu-B3 g ≥ b = m ≥ d = i = h = f≥ a ≥ c for R[subscript]max and Glu-B3 i = d ≥ g = f = m ≥ b = c = h = a for Ext.; Glu-D3 a-Gli-D1 = f ≥ c = d = a ≥ b for R[subscript]max and Glu-D3 d ≥ a-Gli-D1 ≥ a ≥ b = c = f for Ext. The influence of protein content and two-way glutenin allele interactions are also discussed. Another aspect of this work investigated the relationship between HMW-GS expression levels and quality. RP-HPLC was used to quantify the proportion (% area) of individual HMW-GSs relative to total HMW-GSs. Except for Glu-BId (6+8*), the B-genome contributed the highest percentage of HMW-GSs and was significantly higher (P<O.OO1) in cultivars that contained the Glu-BIal allele. A high proportion of IBx subunits compared to IDx subunits (= 2.3, Glu-B1al) correlated with varieties reported to have extra strong dough properties, while a 1Bx:1Dx ratio of = 1.3 (Glu-B1 i, f, c, u and ak) was typical of varieties with moderate to high dough strength characteristics. In varieties which contain Glu-B1 alleles reported to produce weak: doughs the 1Bx:I1Dx value was = 1.0 (Glu-B1e) and = 0.6 (Gfu-B1). This suggests that the overall proportion of Glu-B1 subunits has a major influence on dough strength and that the proportion of 1Bx relative to 1Dx subunits, as determined by RP-HPLC, could be used to predict dough quality. RP-HPLC analysis also enabled the identification of varieties that contained the Glu-B1al allele and overexpressed subunit Glu-B1 7x, including the most likely source of this allele in bread wheat cultivars. Novel HMW-GS alleles in related wheat species with good quality potential were also identified. A simple small-scale screening assay was developed to efficiently assess the protein quality attributes associated with accessions of synthetic hexaploids, T tauschii and T dicoccoides. Development of the Turbidity assay is described and was used in conjunction with SE-HPLC and SDS-PAGE to conflrm and characterise previously undescribed HMW-GSs. The HMW-GS composition of T dicoccoides is discussed in detail where there were 49 HMW-GSs which combined to produce 54 different HMW-GS banding patterns. Accordingly, allelic designations were tentatively assigned to either individual or subunit pairs and these are also Teported in this manuscript. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1277743 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Variation in quantity and quality of gluten proteins is largely responsible for the genotypic differences associated with the dough rheological parameters, maximum resistance (R[subscript]max) and extensibility (Ext.). In the context of bread making, doughs characteristic of good quality have moderate to high extensograph maximum resistance (R[subscript]max) and high extensibility (Ext.). The term usually applied to describe the balance between these two parameters is dough strength. Generally, weak doughs perform poorly in baking tests and as dough strength increases, bread making quality also increases. Important proteins that constitute the 'gluten complex' include high molecular weight glutenin subunits (HMW-GSs) and low molecular weight glutenin subunits (LMW-GSs). These proteins, which interact to produce large polymeric proteins, are coded at the Glu-1 and Glu-3 loci on group 1 chromosomes, respectively. Extensive allelic variation exists a1 each of the G/u-1 and Glu-3 loci. Field trials (4 years) and physical dough quality tests on harvested grain from a set of near-isogenic lines, differing in glutenin composition, were used to investigate the effect of numerous glutenin alleles on dough rheological parameters. Glutenin allele main effects were ranked as follows: Glu-A1 a = p = b > c for R[subscript]max and Glu-A1 a = b = p > C for Ext.; Glu-B1 i ≥ b = c > d = a for R[subscript]max and Glu-B1 a = i = c ≥ b ≥ d for Ext.; Glu-D1d > Glu-D1a = Glu-D1b ≥ Glu-D1f for R[subscript]max and Glu-D1 a = b = f ≥ d for Ext.; Glu-A3 d = b ≥ c = f ≥ a > e for R[subscript]max and Glu-A3 b = a = d = c = f ≥ e for Ext.; Glu-B3 g ≥ b = m ≥ d = i = h = f≥ a ≥ c for R[subscript]max and Glu-B3 i = d ≥ g = f = m ≥ b = c = h = a for Ext.; Glu-D3 a-Gli-D1 = f ≥ c = d = a ≥ b for R[subscript]max and Glu-D3 d ≥ a-Gli-D1 ≥ a ≥ b = c = f for Ext. The influence of protein content and two-way glutenin allele interactions are also discussed. Another aspect of this work investigated the relationship between HMW-GS expression levels and quality. RP-HPLC was used to quantify the proportion (% area) of individual HMW-GSs relative to total HMW-GSs. Except for Glu-BId (6+8*), the B-genome contributed the highest percentage of HMW-GSs and was significantly higher (P<O.OO1) in cultivars that contained the Glu-BIal allele. A high proportion of IBx subunits compared to IDx subunits (= 2.3, Glu-B1al) correlated with varieties reported to have extra strong dough properties, while a 1Bx:1Dx ratio of = 1.3 (Glu-B1 i, f, c, u and ak) was typical of varieties with moderate to high dough strength characteristics. In varieties which contain Glu-B1 alleles reported to produce weak: doughs the 1Bx:I1Dx value was = 1.0 (Glu-B1e) and = 0.6 (Gfu-B1). This suggests that the overall proportion of Glu-B1 subunits has a major influence on dough strength and that the proportion of 1Bx relative to 1Dx subunits, as determined by RP-HPLC, could be used to predict dough quality. RP-HPLC analysis also enabled the identification of varieties that contained the Glu-B1al allele and overexpressed subunit Glu-B1 7x, including the most likely source of this allele in bread wheat cultivars. Novel HMW-GS alleles in related wheat species with good quality potential were also identified. A simple small-scale screening assay was developed to efficiently assess the protein quality attributes associated with accessions of synthetic hexaploids, T tauschii and T dicoccoides. Development of the Turbidity assay is described and was used in conjunction with SE-HPLC and SDS-PAGE to conflrm and characterise previously undescribed HMW-GSs. The HMW-GS composition of T dicoccoides is discussed in detail where there were 49 HMW-GSs which combined to produce 54 different HMW-GS banding patterns. Accordingly, allelic designations were tentatively assigned to either individual or subunit pairs and these are also Teported in this manuscript. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1277743 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007

This thesis describes an investigation of the mechanistic differences of hard and soft wheat varieties in the course of dough formation. These two classes of wheat exhibit dissimilar end-use, as hard wheat flour is known for its bread making attributes, whereas soft wheat flour is suitable for cake and cookie production. This difference is related to the grain hardness, protein content and property of gluten, in addition to chemical interactions that are occurring during dough making. Covalent and hydrophobic interactions, as well as hydrogen bond formation, are the main interactions that take place during dough mixing. However, the contribution of each interaction in dough formation of hard and soft wheat is not known. One variety of hard and one variety of soft wheat flour were mixed to their optimum hydration level (500 BU), as determined by farinograph. The extent of covalent interactions of gluten proteins during dough mixing was examined by monitoring changes in the solubility of flour proteins in a 2% Sodium Dodecyl Sulfate (SDS) media. Moreover, the contribution of thiol groups to covalent bond was examined by measuring the changes in the accessible thiols throughout the mixing. Lower extractability of proteins and accessible thiols of hard wheat dough, compared to soft wheat dough, indicated the predominant role of covalent interactions in hard wheat dough. The complementary results from Size Exclusion High Performance Liquid Chromatography (SE-HPLC) indicated that covalent interaction of hard wheat dough primarily occurs between Low Molecular Weight (LMW) and High Molecular Weight (HMW) gluten proteins, whereas this interaction mainly occurs among LMW proteins in soft wheat doughs. Fewer hydrophobic interactions in hard wheat dough in compare with soft wheat measured by Front-face fluorescence spectroscopy indicated that this interaction is more dominant in soft wheat dough. Study of the conformational change in secondary structure of protein (indirect approach to monitor hydrogen bond) by fourier transform infrared (FTIR) spectroscopy showed that β-sheets are formed in both varieties at their optimum dough strength. In hard wheat dough this structure resulted mainly from disulfide linkages, whereas in soft wheat dough this structure is more likely the result of hydrophobic interactions.

By-products of fruit, cereal and vegetable processing are often regarded as waste while they contain significant amounts of dietary fibre and phytochemicals that can positively contribute to the human diet when reused as food ingredient. The application of fibre from by-products in baked goods could increase the sustainability of the processing chain but is usually associated with changes in product characteristics, such as lower volume, denser structure and increased hardness. In the current study, the interactions of fibres from by-products and wheat macromolecules were analysed in muffins, starch slurries and wheat doughs. The three selected fibres differed significantly in their chemical composition and technofunctional properties. In muffins wheat flour replacement by apple fibre was assessed by rheological measurements of batter and determination of product characteristics. Water proportion adaption based on batter viscosity to create isoviscosity was evaluated as a promising method to develop muffins with satisfying characteristics, where a wheat flour replacement of 30 % is suggested. The addition of apple fibre influenced starch gelatinisation in muffins during baking as indicated by the results of pasting experiments and in vitro starch digestion. Starch slurries with apple and wheat fibre were analysed in pasting experiments. Soluble dietary fibre, mainly pectin, strongly influenced the pasting profile of wheat starch, in comparison to insoluble dietary fibre, that acted as an inert filler and did not interact with the starch. Wheat doughs with fibre from by-products were analysed for rheology, texture and microstructure. The gluten development was negatively influenced by the fibres, which resulted in less extensible doughs. Soluble dietary fibre resulted in increased dough stickiness and limited dough handling at high application levels. It can be reasoned that dough with 10% fibre from by-products would produce products with satisfying characteristics, whereas higher application levels cannot be recommended without using additives to increase the gluten strength. Fibres from by-products are suitable wheat flour replacers in bakery products, where the negative effects of the high water binding capacity of the fibre, can be partly balanced by water proportion adaption, especially in products were gluten development is not that dominating for product structure, like in muffins or cakes. / Nebenprodukte der Obst-, Getreide- und Gemüseverarbeitung werden oft als Abfall betrachtet, wobei sie signifikante Gehalte an Ballaststoffen und sekundären Pflanzeninhaltsstoffen aufweisen, und bei der Verwendung als Lebensmittelzutat positiv zur menschlichen Ernährung beitragen können. Die Anwendung von Fasern aus Nebenprodukten in Backwaren könnte die Nachhaltigkeit der Verarbeitungskette erhöhen, ist jedoch mit Änderungen der Produkteigenschaften verbunden, wie verringertes Volumen, dichtere Struktur und erhöhte Härte. In der vorliegenden Studie wurden die Wechselwirkungen von Fasern und Weizenmakromolekülen in Muffins, Stärkesuspensionen und Weizenteigen analysiert, wobei sich die drei ausgewählten Fasern in ihrer chemischen Zusammensetzung und ihren technofunktionellen Eigenschaften unterschieden. In Muffins wurde die Mehlsubstitution durch Apfelfaser anhand von Teigrheologie und Produkteigenschaften analysiert. Die Anpassung des Wassergehaltes basierend auf der Teigviskosität wurde als vielversprechende Methode zur Entwicklung von Muffins mit akzeptablen Eigenschaften bewertet, wodurch ein Mehlersatz von 30% möglich war. Die Zugabe von Apfelfasern beeinflusste die Stärkeverkleisterung in Muffins, wie durch die Ergebnisse von Verkleisterungsexperimenten und In vitro-Stärkeverdauung gezeigt wurde. Stärkesuspensionen mit Apfel- und Weizenfasern wurden auf ihr Verkleisterungsverhalten analysiert. Lösliche Ballaststoffe beeinflussten das Verkleisterungsprofil von Weizenstärke im Vergleich zu unlöslichen Ballaststoffen, die als inerter Füllstoff fungierten und nicht mit der Stärke in Wechselwirkung traten. Weizenteige mit Fasern wurden auf Rheologie, Textur und Mikrostruktur untersucht. Die Glutenentwicklung wurde durch die Fasern negativ beeinflusst, was zu weniger dehnbaren Teigen führte. Lösliche Ballaststoffe führten zu einer erhöhten Teigklebrigkeit. Weizenteig mit 10% Faser besitzt zufriedenstellenden Eigenschaften, während höhere Fasermengen nicht zu empfehlen sind, ohne Zusatzstoffe, um die Glutenfestigkeit zu erhöhen. Fasern aus Nebenprodukten sind geeignet als Mehlersatz in Backwaren, wobei die negativen Auswirkungen der hohen Wasserbindekapazität der Faser teilweise durch Wasseranpassung ausgeglichen werden können, insbesondere in Produkten, bei denen die Glutenentwicklung nicht die Produktstruktur dominiert, wie in Muffins oder Kuchen.

By-products of fruit, cereal and vegetable processing are often regarded as waste while they contain significant amounts of dietary fibre and phytochemicals that can positively contribute to the human diet when reused as food ingredient. The application of fibre from by-products in baked goods could increase the sustainability of the processing chain but is usually associated with changes in product characteristics, such as lower volume, denser structure and increased hardness. In the current study, the interactions of fibres from by-products and wheat macromolecules were analysed in muffins, starch slurries and wheat doughs. The three selected fibres differed significantly in their chemical composition and technofunctional properties. In muffins wheat flour replacement by apple fibre was assessed by rheological measurements of batter and determination of product characteristics. Water proportion adaption based on batter viscosity to create isoviscosity was evaluated as a promising method to develop muffins with satisfying characteristics, where a wheat flour replacement of 30 % is suggested. The addition of apple fibre influenced starch gelatinisation in muffins during baking as indicated by the results of pasting experiments and in vitro starch digestion. Starch slurries with apple and wheat fibre were analysed in pasting experiments. Soluble dietary fibre, mainly pectin, strongly influenced the pasting profile of wheat starch, in comparison to insoluble dietary fibre, that acted as an inert filler and did not interact with the starch. Wheat doughs with fibre from by-products were analysed for rheology, texture and microstructure. The gluten development was negatively influenced by the fibres, which resulted in less extensible doughs. Soluble dietary fibre resulted in increased dough stickiness and limited dough handling at high application levels. It can be reasoned that dough with 10% fibre from by-products would produce products with satisfying characteristics, whereas higher application levels cannot be recommended without using additives to increase the gluten strength. Fibres from by-products are suitable wheat flour replacers in bakery products, where the negative effects of the high water binding capacity of the fibre, can be partly balanced by water proportion adaption, especially in products were gluten development is not that dominating for product structure, like in muffins or cakes. / Nebenprodukte der Obst-, Getreide- und Gemüseverarbeitung werden oft als Abfall betrachtet, wobei sie signifikante Gehalte an Ballaststoffen und sekundären Pflanzeninhaltsstoffen aufweisen, und bei der Verwendung als Lebensmittelzutat positiv zur menschlichen Ernährung beitragen können. Die Anwendung von Fasern aus Nebenprodukten in Backwaren könnte die Nachhaltigkeit der Verarbeitungskette erhöhen, ist jedoch mit Änderungen der Produkteigenschaften verbunden, wie verringertes Volumen, dichtere Struktur und erhöhte Härte. In der vorliegenden Studie wurden die Wechselwirkungen von Fasern und Weizenmakromolekülen in Muffins, Stärkesuspensionen und Weizenteigen analysiert, wobei sich die drei ausgewählten Fasern in ihrer chemischen Zusammensetzung und ihren technofunktionellen Eigenschaften unterschieden. In Muffins wurde die Mehlsubstitution durch Apfelfaser anhand von Teigrheologie und Produkteigenschaften analysiert. Die Anpassung des Wassergehaltes basierend auf der Teigviskosität wurde als vielversprechende Methode zur Entwicklung von Muffins mit akzeptablen Eigenschaften bewertet, wodurch ein Mehlersatz von 30% möglich war. Die Zugabe von Apfelfasern beeinflusste die Stärkeverkleisterung in Muffins, wie durch die Ergebnisse von Verkleisterungsexperimenten und In vitro-Stärkeverdauung gezeigt wurde. Stärkesuspensionen mit Apfel- und Weizenfasern wurden auf ihr Verkleisterungsverhalten analysiert. Lösliche Ballaststoffe beeinflussten das Verkleisterungsprofil von Weizenstärke im Vergleich zu unlöslichen Ballaststoffen, die als inerter Füllstoff fungierten und nicht mit der Stärke in Wechselwirkung traten. Weizenteige mit Fasern wurden auf Rheologie, Textur und Mikrostruktur untersucht. Die Glutenentwicklung wurde durch die Fasern negativ beeinflusst, was zu weniger dehnbaren Teigen führte. Lösliche Ballaststoffe führten zu einer erhöhten Teigklebrigkeit. Weizenteig mit 10% Faser besitzt zufriedenstellenden Eigenschaften, während höhere Fasermengen nicht zu empfehlen sind, ohne Zusatzstoffe, um die Glutenfestigkeit zu erhöhen. Fasern aus Nebenprodukten sind geeignet als Mehlersatz in Backwaren, wobei die negativen Auswirkungen der hohen Wasserbindekapazität der Faser teilweise durch Wasseranpassung ausgeglichen werden können, insbesondere in Produkten, bei denen die Glutenentwicklung nicht die Produktstruktur dominiert, wie in Muffins oder Kuchen.