Master of Science / Department of Grain Science and Industry / Yong-Cheng Shi / Jon M. Faubion / One long-term goal of cereal science research is to increase the shelf life of baked products and one approach to that goal has been the use of emulsifiers. Emulsifiers are surface-active agents, some of which improve specific properties of baked products. Two emulsifiers, sodium stearoyl lactylate (SSL) and oleyl lactylic acid (OLA) are similar in structure, the difference being the acid moiety: stearic versus oleic acid. Widely researched, SSL has found many uses in baked products. However, how OLA interacts with starch/flour in baked products or how that interaction affects product quality is not well understood. The objective of this study was to understand the interactions between normal wheat starch and these emulsifiers, as well as the differences between SSL and OLA in those regards. The effects of the two emulsifiers on the pasting properties of wheat starch and wheat flour were determined using a MicroViscoAmylograph. Heating at 6oC/min with increased emulsifier concentration (0-2%) resulted in increased hot paste viscosity and apparent interaction of both emulsifiers with wheat starch. Solid content affected both maximum hot and final viscosity. OLA produced increased maximum hot and final viscosities with increased starch concentration and emulsifier concentrations. For wheat flour, higher concentrations of SSL reduced both maximum hot paste and final viscosities. OLA behaves differently with wheat flour. At lower flour concentrations, higher concentrations of OLA reduced maximum hot viscosity. The effects of SSL on starch were affected by an increased heating and cooling rate (10oC/min). Heating stage microscopic analysis revealed that the presence of emulsifiers inhibited granular swelling beyond the normal gelatinization temperature (65oC) in both starch and flour systems. OLA’s effect in this respect was greater than that of SSL. Complex formation between emulsifiers and wheat starch and wheat flour was determined using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). For isolated wheat starch and hard wheat flour, DSC and XRD indicated that OLA complexes to a greater extent than does SSL. For flour, XRD indicated no difference exhibited in the interaction of the emulsifiers with the flours. KEYWORDS: Emulsifiers, Starch, Wheat flour

LD2668 .T4 1949 P41 / Master of Science

Digitized by Kansas Correctional Industries

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Typescript (photocopy). / Digitized by Kansas Correctional Industries

Soy enhances the protein quality of wheat bread because of its lysine content which is deficient in wheat. The aim of this work was to use high levels of soy flour in wheat bread in order to maximise the potential of soy flour protein in an attempt to address Protein Energy Malnutrition in developing counties. Raw soy flour (RSF) and physically modified soy flours (PMSF1 and PMSF2) were used for the preparation of the composite dough with wheat flour. The two physically modified soy flours were prepared by steam flushing (PMSF2) and water boiling (PMSF1) of raw soy beans before flour preparation. Physical modification of soy flour was chosen over chemical modification because of its practical significance in developing countries. The Farinograph and Extensograph were used to study the effect of Lascorbic acid and physical modification of soy flour on the rheological properties of soy-wheat composite doughs at various ratios up to 50% soy flour. Soy-wheat composite doughs made from physically modified soy flour (PMSF) exhibited higher resistance to extension (Rm), greater tolerance to mixing, better mixing stability, higher water uptake rate and water absorption than the soy-wheat composite doughs made from raw soy flour (RSF).The physical modification process provides a relatively simple method for improving the baking quality of soy flour, in combination with wheat flour, for use at the village level in regions where soy can be grown and where wheat grain is imported. Using physically modified soy flour (PMSF2) to prepare soy-wheat dough, a mathematical model was developed from estimated regression coefficients of L-ascorbic acid and water percentages (30% w/w soy flour) on soy-wheat dough DSC water evaporation enthalpies. The model was successfully used for the prediction of loaf volumes and for the formulation of soy-wheat breads. A daily serving of 100 to 200 grams of this bread was calculated to provide 60 -100% of the lysine and protein requirements (FAO/WHO) of children and adults. The resultant breads developed in this project thus offer an attractive and sustainable food that is nutritionally superior. / Doctor of Philosophy (PhD)

This research provides a new insight on various properties, such as rheological, mechanical, and flame-retarding properties, as well as the foaming behaviors of wood flour /plastic composites (WPCs) through the addition of a small amount of nanosized clay particles. Although WPCs have replaced natural wood in many applications, their industrial usage has been limited because of their weak modulus, low impact strength, low screwing-ability/nailing-ability, high density compared to natural wood, as well as their flammability compared to plastics. In this context, the incorporation of nanoclay and foam structure into WPC has been studied to dramatically alleviate these drawbacks. The melt blending method was used to prepare different types of clay-filled wood flour composites such as intercalated and exfoliated clay nanocomposites. The effects of key processing variables such as the mixing time, mixing temperature and screw speed on clay dispersion were investigated from the thermodynamic and kinetic point of view. Their nanostructure was determined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Accordingly, effective strategies for controlling intercalation and exfoliation of polyolefin/clay nanocomposites were proposed and evaluated. Wood flour composites with high levels of clay dispersion were synthesized successfully using a general new route (i.e., maleated-polyolefin-based clay masterbatch and dilution). The effects of nanoclay particles on the rheological, thermal, and mechanical properties were identified. In addition, it was demonstrated that a small amount of well-dispersed nanoclay in WPC significantly improved flame retardancy of WPCs. The mechanism of improved flame-retarding effects on nanoparticles was elucidated as well. The relationship between the clay dispersion and the material properties were also clarified. Furthermore, the foaming behaviors of HDPE-based and PP-based wood flour/nanoclay composites were investigated using N2 as the blowing agent in an extrusion process. The cell nucleation and growth behaviors of wood flour/polyolefin/clay composite foams were elucidated while varying the temperature, pressure, wood flour content, clay content and dispersion degrees.

This research provides a new insight on various properties, such as rheological, mechanical, and flame-retarding properties, as well as the foaming behaviors of wood flour /plastic composites (WPCs) through the addition of a small amount of nanosized clay particles. Although WPCs have replaced natural wood in many applications, their industrial usage has been limited because of their weak modulus, low impact strength, low screwing-ability/nailing-ability, high density compared to natural wood, as well as their flammability compared to plastics. In this context, the incorporation of nanoclay and foam structure into WPC has been studied to dramatically alleviate these drawbacks. The melt blending method was used to prepare different types of clay-filled wood flour composites such as intercalated and exfoliated clay nanocomposites. The effects of key processing variables such as the mixing time, mixing temperature and screw speed on clay dispersion were investigated from the thermodynamic and kinetic point of view. Their nanostructure was determined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Accordingly, effective strategies for controlling intercalation and exfoliation of polyolefin/clay nanocomposites were proposed and evaluated. Wood flour composites with high levels of clay dispersion were synthesized successfully using a general new route (i.e., maleated-polyolefin-based clay masterbatch and dilution). The effects of nanoclay particles on the rheological, thermal, and mechanical properties were identified. In addition, it was demonstrated that a small amount of well-dispersed nanoclay in WPC significantly improved flame retardancy of WPCs. The mechanism of improved flame-retarding effects on nanoparticles was elucidated as well. The relationship between the clay dispersion and the material properties were also clarified. Furthermore, the foaming behaviors of HDPE-based and PP-based wood flour/nanoclay composites were investigated using N2 as the blowing agent in an extrusion process. The cell nucleation and growth behaviors of wood flour/polyolefin/clay composite foams were elucidated while varying the temperature, pressure, wood flour content, clay content and dispersion degrees.

A study was conducted to quantify the relationships between growing season weather conditions and end-use quality of Canada Western Red Spring (CWRS) wheat (Triticum aestivum) grown in producer fields across western Canada (Alberta, Saskatchewan and Manitoba). Grain samples received an official grade at the Canadian Grain Commission and were milled into flour using a Buhler flour. Flour samples underwent an extensive analysis of flour, dough, and breadmaking quality. Daily precipitation amounts and maximum/minimum temperatures were accumulated for each field and then compared to quality data. In this study we also investigated the effectiveness of the Canadian grain grading system’s ability to segregate wheat samples into levels of increasing quality performance and uniformity. We found that for several flour and dough quality analysis, this was often achieved for either quality performance or uniformity, but there was not an improvement in both with an improvement in grade except in bread quality. / October 2006

A cost-effective, faster and efficient way of screening wheat samples suitable for tortilla production is needed. Hence, we developed prediction models for tortilla quality (diameter, specific volume, color and texture parameters) using grain, flour and dough properties of 16 wheat flours. The prediction models were developed using stepwise multiple regression. Dough rheological tests had higher correlations with tortilla quality than grain and flour chemical tests. Dough resistance to extension was correlated best with tortilla quality, particularly tortilla diameter (r= -0.87, P<0.01). Gluten index was significantly correlated with tortilla diameter (r = -0.67, P less than 0.01) and specific volume (r = -0.73, P less than 0.01). Tortilla diameter was the parameter best predicted. An r2 of 0.87 was obtained when mix-time and dough resistance to extension were entered into the model. This model was validated using another sample set, and an r^2 of 0.91 was obtained. Refined and whole wheat flours, dough and tortillas were compared using five wheat samples. Refined flour doughs were more extensible and softer than whole wheat flour doughs. Whole wheat flour tortillas were larger, thinner and less opaque than refined flour tortillas. Refined wheat flour had much smaller particle size and less fiber than whole wheat flour. These are the major factors that contributed to the observed differences. In general, refined wheat tortillas were more shelf-stable than whole wheat tortillas. However, whole wheat tortillas from strong flours had excellent shelf-stability which must be considered when whole wheat tortillas are processed. . Different objective rheological techniques were used to characterize the texture of refined and whole flour tortillas during storage. Differences in texture between 0, 1 and 4 day-old tortillas were detected by rupture distance from one and two-dimension extensibility techniques. In general, the deformation modulus was not a good parameter to differentiate tortilla texture at the beginning of storage. It detected textural changes of 8 and 14 day-old tortillas. The subjective rollability method detected textural changes after 4 days storage.