This thesis is based on observations of the physical properties of wheat flour dough using ultrasonic measurements. Three frequency ranges were used in the study, low frequencies (near 40 kHz), intermediate frequencies (1 to 5 MHz, where bubble resonance effects are apparent), and high frequencies (near 20 MHz). Doughs mixed under different head space air pressures, from vacuum to atmospheric pressure, as well as under nitrogen, were studied at low frequency to investigate their relaxation behavior. Subsamples from ambient dough and vacuum dough displayed differences in the dependence of velocity and attenuation on time after compression, but no post mixing relaxation effect was apparent. A critical headspace pressure of approximately 0.16 atmospheres determined whether vacuum-like or ambient-like relaxation was observed. A peak in attenuation and changes in ultrasonic velocity were observed around the bubble resonance frequency, and these ultrasonic parameters changed substantially as a function of time. A bubble resonance model was used to interpret the results around the bubble resonance frequency, and bubble size distributions were estimated for ambient and vacuum dough from the ultrasonic data. For the high frequency range, a molecular relaxation model was used to interpret the results. Different fast relaxation times were observed for ambient dough (5 ns) and vacuum dough (1 ns). This relaxation time may be associated with conformational rearrangements in glutenin inside the dough matrix. These experiments have enabled dough relaxation to be probed over a very wide range of time scales (from ns to hours), and will lead to a better understanding of the role of dough matrix and gas cell effects on the physical properties of wheat flour doughs. / October 2007

This thesis is based on observations of the physical properties of wheat flour dough using ultrasonic measurements. Three frequency ranges were used in the study, low frequencies (near 40 kHz), intermediate frequencies (1 to 5 MHz, where bubble resonance effects are apparent), and high frequencies (near 20 MHz). Doughs mixed under different head space air pressures, from vacuum to atmospheric pressure, as well as under nitrogen, were studied at low frequency to investigate their relaxation behavior. Subsamples from ambient dough and vacuum dough displayed differences in the dependence of velocity and attenuation on time after compression, but no post mixing relaxation effect was apparent. A critical headspace pressure of approximately 0.16 atmospheres determined whether vacuum-like or ambient-like relaxation was observed. A peak in attenuation and changes in ultrasonic velocity were observed around the bubble resonance frequency, and these ultrasonic parameters changed substantially as a function of time. A bubble resonance model was used to interpret the results around the bubble resonance frequency, and bubble size distributions were estimated for ambient and vacuum dough from the ultrasonic data. For the high frequency range, a molecular relaxation model was used to interpret the results. Different fast relaxation times were observed for ambient dough (5 ns) and vacuum dough (1 ns). This relaxation time may be associated with conformational rearrangements in glutenin inside the dough matrix. These experiments have enabled dough relaxation to be probed over a very wide range of time scales (from ns to hours), and will lead to a better understanding of the role of dough matrix and gas cell effects on the physical properties of wheat flour doughs.

This thesis is based on observations of the physical properties of wheat flour dough using ultrasonic measurements. Three frequency ranges were used in the study, low frequencies (near 40 kHz), intermediate frequencies (1 to 5 MHz, where bubble resonance effects are apparent), and high frequencies (near 20 MHz). Doughs mixed under different head space air pressures, from vacuum to atmospheric pressure, as well as under nitrogen, were studied at low frequency to investigate their relaxation behavior. Subsamples from ambient dough and vacuum dough displayed differences in the dependence of velocity and attenuation on time after compression, but no post mixing relaxation effect was apparent. A critical headspace pressure of approximately 0.16 atmospheres determined whether vacuum-like or ambient-like relaxation was observed. A peak in attenuation and changes in ultrasonic velocity were observed around the bubble resonance frequency, and these ultrasonic parameters changed substantially as a function of time. A bubble resonance model was used to interpret the results around the bubble resonance frequency, and bubble size distributions were estimated for ambient and vacuum dough from the ultrasonic data. For the high frequency range, a molecular relaxation model was used to interpret the results. Different fast relaxation times were observed for ambient dough (5 ns) and vacuum dough (1 ns). This relaxation time may be associated with conformational rearrangements in glutenin inside the dough matrix. These experiments have enabled dough relaxation to be probed over a very wide range of time scales (from ns to hours), and will lead to a better understanding of the role of dough matrix and gas cell effects on the physical properties of wheat flour doughs.

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

Master of Science / Department of Grain Science and Industry / Yong-Cheng Shi / Jon Faubion / The rheological properties of two waxy and two normal wheat flours were investigated and the observed differences between them were explained by biochemical analysis. Protein analysis showed that waxy flour had lower polymeric to monomeric ratio (0.70 and 0.58 for waxy flour compared to 0.75 and 0.76 for normal flour) and higher gliadin content in waxy wheat dough (43.9 and 47.3 for waxy wheat dough compared to 41.0 and 41.7 for normal wheat dough). Waxy flour had high amounts of insoluble (IPP) and unextractable (UPP) polymeric protein despite the poor dough forming properties of the waxy flours, contrary to previous correlations made between IPP, UPP and dough strength. Gluten index determination showed a clear difference between waxy and normal flour; there was no gluten aggregation when the waxy samples were tested. The determination of gluten index done on a variety of water washed flour samples indicated that the water-extractable fraction may contain compounds that affect gluten aggregation. HPLC analysis coupled with arabinose/xylose ratio and viscosity determination of the water extractable portion of the flour indicated that water extractable arabinoxylans (WEAX) in waxy wheat flour were different in composition and conformation. Further research is needed to determine if they could be responsible for the lack of gluten aggregation in waxy flour.

Gas cells make up a significant proportion of bread’s volume and are responsible for a number of bread’s characteristics, making their size distribution throughout bread an important quality parameter. The number and size of cells affect the texture and volume of bread, the quantity of sauce mopped up, and how bright the bread appears. Gas cells are incorporated into bread dough during mixing and manipulated throughout the breadmaking process to obtain the desired cellular structure. Due to the fragile nature of bread dough, obtaining accurate quantitative data on its cellular structure is challenging. This thesis investigates the cellular structure of bread, as well as assessing the effect of sugar during breadmaking. Magnetic resonance imaging (MRI), microscopy and X-ray computerised tomography (X-ray CT) have been used throughout research in bread dough to visualise dough’s cellular structure. A non-destructive and non-invasive method giving a high resolution is X-ray CT, in particular when using a synchrotron light source. However, time on a synchrotron beamline is highly competitive, and can require applications more than two years in advance. Running costs of experiments from a synchrotron beamline are also high. This thesis details an alternative X-ray set-up to accurately visualise dough’s cellular structure using a conventional and therefore more easily accessible X-ray source. Three X-ray CT experiments were conducted to investigate dough’s cellular structure throughout mixing, during proving and in different sugar content doughs. The resolution of the scans varied from 7-11 µm. Industrial bread dough mixing is often conducted at a high pressure initially to improve oxygen availability, followed by a period of partial vacuum to favourably manipulate the cell size distribution. Using X-ray CT, dough cell size distribution was measured at different points throughout pressure-vacuum and constant pressure mixing. A simplified population balance model was fitted to the measured cell size distributions and the validity of the assumptions within the simplified model explored. It was shown that the dynamic changes in the cell size distribution within bread dough could be accurately measured during pressure step change mixing with a non-synchrotron X-ray source. Pressure-vacuum mixing was shown to give a finer cell distribution than constant pressure mixing and the observed decrease in cell number density was found to be much more short lived than the decrease in cell size. The model was found to provide a reasonably accurate characterisation of pressure-vacuum mixing. X-ray CT was also used to monitor dough’s changing cellular structure during proving by taking scans every 5 minutes over 145 minutes. Dough voidage increased from 3% to 66%, resulting in a volume increase from 544 mm3 to 1293 mm3. Cell growth was quickest between 40 and 140 minutes, where a steady increase in volume and significant changes in the cell structure occurred. A change in voidage distribution was observed, with greater proportions of gas located in larger cells over time. In addition, over the course of proving cell numbers dropped, a 156-fold increase in mean cell volume occurred, and mean cell Feret shape increased from 1.59 to 1.91. This in-situ method of X-ray imaging of bread dough provides higher resolution images than comparable data from conventional X-ray sources. In addition, the method has proved to be effective in obtaining high resolution and high contrast 3D images of the cellular structure of dough. This technique will help those wanting to investigate cellular changes in the dough dynamically, but without the waiting time and applications that are required with synchrotron X-rays. On investigating the effect of sugar during breadmaking, sugar was found to increase the gas free dough density and dough voidage, change the dough’s rheology, increase its proving time and produce denser bread. Application of a population balance model on the experimental results indicate that the decrease in steady state voidage as the sugar content increases is a result of an increase in disentrainment. This was reflected in the X-ray CT of sugared vs. non-sugared doughs through fewer and smaller cells present in sugared doughs. This is likely to be a result of a weaker dough structure, making cell rupture more likely. The Chorleywood Bread Process (CBP) is used industrially worldwide for the production of bread in less time and using inferior ingredients compared to the traditional bulk fermentation process, making it more cost effective. These results show that simply extending the pressure vacuum mixing used for the production of standard bread loaves in the CBP to sugared doughs should be avoided as aeration of sugared doughs differs to non-sugared doughs. The results suggest that to do so would be detrimental to the product quality.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The present work proposes a solution for the conditioning of bakery dough with the purpose of reducing costs by replacing manual work with a mechanized system that will be a piston extruder. In the process, the mass will be contained within a 304 stainless steel prismatic matrix with multiple outlet openings for optimization of the production line. The mechanical properties of bread dough were studied for the design of the platform and the estimation of the necessary compression force. A linear actuator was used, which exerts a compression force of 6 kN, which maximum linear speed is 5 mm/s. Validation of results will be carried out through simulated tests with a density mass of 1452.9 kg/m3. The system is composed of a linear actuator that performs the function of an extruder, followed by a pneumatic wire cutter. The process continues with a conveyor belt and ends with the injection of sesame seeds.The fundamental contribution is in the design of the extrusion chamber, since it allows the flow of the mass leaving minimal residue.

The objective of this study was to evaluate the impact of maturity at harvest and dietary inclusion rate of triticale silage on the production performance and nutrient utilization of lactating dairy cows. The hypothesis was that the production performance of lactating dairy cows would increase when consuming triticale harvested and ensiled at the boot stage of maturity (BS), as compared to consuming triticale harvested and ensiled at the soft-dough stage of maturity (SDS), and that the difference would be greater in high-forage diets. A single field of triticale was planted, and harvested at the BS or SDS of maturity, and the harvested forage was ensiled in separate bunker silos. Eight primiparous and 16 multiparous Holstein cows were assigned to 1 of 4 diets in a replicated 4 × 4 Latin square design with 21-d periods. Cows were fed once daily (10:00 a.m.) using a Calan gate system (American Calan Inc., Northwood, NH). Diets included BS or SDS triticale silage with dietary forage inclusion of 54% (high-forage; HF) or 36% (low-forage; LF). Cows consuming diets containing BS silage produced more milk per day than cows consuming diets containing SDS silage. This response was observed when feeding both LF and HF diets. The maturity of the forage (BS vs. SDS) did not affect the apparent total tract digestibility of neutral detergent fiber (NDF) or the yield of energy-corrected milk. Cows consuming diets containing BS silage yielded more milk protein and lactose per day than cows consuming diets containing SDS silage, and we also observed this response when feeding both LF and HF diets. When fed the LF diets, cows had a higher apparent total-tract digestibility on CP and NDF, whereas apparent total-tract starch digestibility was higher in cows fed HF diets. Cows consuming LF diets exhibited higher levels of de novo fatty acid synthesis compared to those on HF diets. Feeding LF diets yielded more C14:1, C18:1 trans-9, and unknown fatty acids, while C16:0, C18:1 trans-10, CLA cis-9, trans-11, and CLA trans-10, cis-12 fatty acids yielded more in cows fed with SDS diets. Notably, CLA cis-9, trans-11, and CLA trans-10, cis-12 fatty acids were highest in SDS diets. Additionally, stearic fatty acid (C18:0) concentrations increased in HF diets and SDS silage. In conclusion, the study found that triticale maturity at harvest minimally affects dairy cow performance, with consistent milk production across harvest stages. While nutrient variations were observed, the conclusion emphasizes the importance of considering not only forage quality but also agronomic management and planting schedules for subsequent crops when deciding on harvest timing. / Master of Science / Cool-season or winter annual grasses, also known as small grain grasses, can be cultivated as cover crops to protect or improve the quality of the soil when the warm-season primary crop (e.g., corn) is not growing. These crops are grown during intervals between regular crop production periods. In the context of cover cropping in the United States, small grains are planted during the fall and winter seasons. One of these small grain crops is triticale, a hybrid resulting from the crossbreeding of wheat and rye. Whole plant triticale is ideal for preservation by ensiling due to its high level of water-soluble carbohydrates, low buffering capacity, and easily controllable moisture content. The objectives of this study were to evaluate the impact of harvesting maturity and dietary inclusion rate of whole plant triticale silage on milk production performance and nutrient utilization of lactating dairy cows. The hypothesis was that the production performance of lactating dairy cows would increase when consuming triticale harvested and ensiled at the boot stage of maturity (BS), as compared to consuming triticale harvested and ensiled at the soft-dough stage of maturity (SDS), which is more advanced in maturity. A single field of triticale was planted, harvested at either BS or SDS and ensiled in separate bunker silos. Twenty-four Holstein cows were grouped by days in milk and daily milk production in groups of 4 cows each, and each group was assigned to one of four experimental diets. Regardless of inclusion rate, cows consuming BS diets yielded more milk, milk protein, and lactose than did cows on SDS diets and for milk yield, we observed this response when feeding both LF and HF diets. The maturity at harvest did not affect dry matter, crude protein, neutral detergent fiber, or starch digestibility of the diets. Crude protein and neutral detergent fiber digestibility were higher in cows consuming low-forage diets than in cows consuming high-forage diets, whereas starch apparent total-tract digestibility was higher in cows fed HF diets. In conclusion, the study found that triticale maturity at harvest minimally affects dairy cow performance, with consistent milk production across harvest stages. While nutrient variations were observed, the conclusion emphasizes the importance of considering not only forage quality but also agronomic management and planting schedules for subsequent crops when deciding on harvest timing.

Viscosity of 30 and 48% soy isolate (Promine-D) dough is determined using an Instron capillary rheometer at 298K, 333K and 363K. Thermal transitions of 10 to 100% soy isolate dough are measured using a Perkin-Elmer Differential Scanning Calorimeter (DSC-2) over 310 to 350K. The observed behavior of the soy isolate doughs is explained in terms of a network based on temporary crosslinks, possibly hydrogen bonds. Additionally, factors which complicate viscosity measurement of these doughs are discussed including yield stresses, melt fracture and sample reservoir pressure losses. / Master of Science