Master of Science / Food Science / John Unruh / A factorial arrangement of treatments was used to evaluate the effects of two subprimal types (chuck roll and knuckle), two quality grades (Premium Choice and Select), and three vacuum storage aging times before processing (7, 21, and 42 d) on ground beef patty display color stability and sensory attributes. At the end of each aging time, four knuckles or two chuck rolls representing their respective quality grade categories were combined and ground to form a sample batch. After a final grind, patties were formed using a patty machine, packaged in overwrapped trays, and displayed in a coffin-type retail case under continuous fluorescent lighting. Ground beef patties from chuck roll and Premium Choice subprimals had brighter red visual color scores, less discoloration, and higher (P<0.05) L*, a*, b*, and chroma values than those from knuckle and Select subprimals, respectfully. With increased display time, patties became (P<0.05) darker red and more discolored and had decreased L*, a*, b*, a/b ratio, and chroma values and increased hue angle values. Ground beef patties from Select knuckle subprimals had greater (P<0.05) oxygen consumption rate (OCR) than those from Premium Choice chuck roll, Select chuck roll and Premium Choice knuckle subprimals. Patties from subprimals aged 42 d had a lower metmyoglobin reducing ability (MRA) than those from subprimals aged 7 and 21 d. Greater aging and display times had higher (P<0.05) aerobic and lactic acid plate counts. In addition, thiobarbituric acid reactive substances values increased (P<0.05) from 7 to 21 d of aging and from 0 to 24 h of display. Ground beef patties from Premium Choice subprimals had a higher MUFA:SFA ratio (P<0.05) than those from Select subprimals. All treatments had acceptable sensory panel results with minimal differences due to treatment. Lower (P<0.05) peak force values for slice shear force and Lee-Kramer were recorded for patties from chuck roll, Premium Choice, and 42 d aged subprimals than those from knuckle, Select, and 7 d aged subprimals, respectfully. Overall, Premium Choice chuck rolls aged for fewer days would result in the most color stability and extended display life.

Master of Agribusiness / Department of Agricultural Economics / Jason Bergtold / ABSTRACT Grands Moulins d'Abidjan (GMA) is a flour milling company operating in Côte d'Ivoire. It wishes to determine the optimal blend of wheat and additives that minimizes its costs of production while meeting its quality specifications. Currently, the chief miller selects the mix of ingredients. The management of the company would like to dispose of a scientific tool that challenges the decisions of the chief miller. The thesis is about building and testing this tool, an optimization model. GMA blends up to six ingredients into flour: soft wheat, hard wheat, gluten, ascorbic acid and two types of enzyme mixes. Quality specifications are summarized into four flour characteristics: protein content, falling number, Alveograph W and specific volume of a baguette after four hours of fermentation. GMA blending problem is transformed into a set of equations. The relationships between ingredients and quality parameters are determined with reference to grains science and with the help of linear regression. The optimization model is implemented in Microsoft Office Excel 2010, in two versions. In the first one (LP for Linear Programming model), it is assumed that weights of additives can take any value. In the second one (ILP for Integer Linear Programming model), some technical constraints restrain the set of values that weights of additives can take. The two models are tested with Premium Solver V11.5 from Frontline Systems Inc., against four situations that actually occurred at GMA in 2011 and 2012,. The solutions provided by the model are sensible. They challenge the ones that were actually implemented. They may have helped GMA save money. The optimization model can nevertheless be improved. The choice of relevant quality parameters can be questioned. Equations that link ingredients and quality parameters, and particularly those determined with the help of linear regression, should be further researched. The optimization model should also take into account some hidden constraints such as logistics that actually influence the decision of GMA chief miller. Finally, sensitivity analyses may also be used to provide alternative solutions.

Doctor of Philosophy / Department of Grain Science and Industry / Yong-Cheng Shi / Starch is the most important source of food energy. However, the information about the metabolic quality of starchy foods is scarce. It is well known that native starches with a B-type X-ray diffraction pattern are more resistant to alpha-amylase digestion than those starches with an A-type X-ray pattern, but the underlying mechanism is not well understood. It is not clear whether the enzyme resistance of B-type starch is due to its B-type crystalline structure or the other structural features in starch granules. The objective of this study was to compare the structure and enzyme digestibility of highly pure A- and B-type starch crystals, and understand the roles of crystalline types in starch digestibility. Highly pure A- and B-type starch crystals were prepared from short linear α-glucans (short-chain amylose) generated from completely debranched waxy starches by manipulating the processing conditions such as starch solids concentration, crystallization temperature and chain length. High concentration, high temperature and short chain length favored the formation of the A-type structure, whereas reverse conditions resulted in the B-type polymorph. Digestion results using a mixture of α-amylase and glucoamylase showed that A-type crystals were more resistant to enzyme digestion than B-type crystals. The A-type crystalline product obtained upon debranching 25% waxy maize starch at 50ºC for 24 h gave 16.6% digestion after 3 h, whereas B-type crystals produced by debranching 5% waxy maize starch at 50ºC for 24 h followed by holding at 25ºC for another 24 h had 38.9% digested after 3 h. The A-type crystals had a higher melting temperature than the B-type crystals as determined by differential scanning calorimetry. Annealing increased the peak melting temperature of the B-type crystals, making it similar to that of the A-type crystals, but did not improve the enzyme resistance. The possible reason for these results was due to more condense packing pattern of double helices in A-type crystallites. It seems that the crystalline types are not the key factor that controls the digestibility of native starch granules. The resistance of native starches with B-type X-ray diffraction pattern is probably attributed to the other structural features in starch granules.

Master of Science / Department of Food Science / Fadi Aramouni / Despite the expansion of the gluten-free (GF) food market, some GF food items are still characterized by an overall mediocre quality. The effects of different types of egg ingredients (fresh, whites, dried) and carob germ flour (CGF) as well as par-baking technology on the quality of dough-based gluten-free sorghum dinner rolls were evaluated. Gluten-free rolls containing 30% of fresh shell eggs or equivalent of egg products and 10% of CGF on a flour basis were evaluated against a control (no egg, no CGF). The feasibility of partial baking of rolls was studied on control as well as fresh eggs and carob germ flour formulas during 5 baking times (0, 8, 10, 12 and 18 minutes). Breads were evaluated for crumb and crust color, specific volume, cell profile, Texture Profile Analysis (TPA) and consumer acceptability. Results showed that rolls containing egg ingredients had higher specific volumes than control (p<0.05) with an increase from 1.45 cm[superscript]3/g to 1.96 cm[superscript]3/g. Carob germ flour did not have a significant effect on specific volume. Eggs also improved cell elongation and produced significantly darker crust (p<0.05). CGF did not appear to have an effect on cell elongation but increased average cell number when combined with egg ingredients, and greatly impacted rolls texture. The combination of fresh eggs or egg whites with CGF reduced significantly (p<0.05) crumb hardness from 2,074 to 1,404g and 1,468g of force respectively. Par-baked dinner rolls displayed similar color, volume, cell profile and texture trends to conventionally baked rolls. Sensory study revealed that acceptability, organoleptic characteristics and willingness to buy of par-baked dinner rolls could be similar to that of conventional wheat products. This research proved that the addition of eggs and CGF to a GF rolls formulation resulted in better overall quality of the product. Moreover, par-baking of the rolls showed great potential to provide safe, convenient and acceptable GF foods to celiac individuals.

Master of Science / Department of Human Nutrition / Tonatiuh Melgarejo / It will be almost impossible to find a household or an informed consumer, completely oblivious to the health risks posed by foods. According to scientific estimates, 48 million cases of foodborne illness occur each year in the United States, causing 128,000 hospitalizations, 3,000 deaths, which costs $6.4-$77.7 billion in expenses by medical care and lost productivity. These illnesses pose a very big constant, perhaps growing, threat to a vast population. Salmonella is the most prevalent foodborne bacteria with more than 1.1 million cases annually in the United States. Increased international trade and distribution, rapid growth in antibiotic resistant bacteria, increase in the number of immunocompromised consumers and changes in agronomic and processing practices poses a very big challenge to monitor, contain and avoid foodborne outbreaks. This can result in contaminated food causing rapid, geographically widespread outbreak. In the wake of numerous recent foodborne illness outbreaks, this report focuses on current safety practices established by research and available to all the consumers. It studies a significant foodborne bacterium (Salmonella), its nature, significance, prevalence, mechanism of action, health risks and preventive safety measures. General food safety practices, to reduce or eliminate the risk, common to all the foodborne bacteria and specially Salmonella, include avoiding cross-contamination, thoroughly cooking foods to right lengths of time and temperature, washing fresh produce and fruits prior to consumption and storing foods at the right temperatures. Strict regulations in safe production, safe processing and consumer awareness is highly recommended. People participation is a must.

Master of Science / Department of Grain Science and Industry / Rebecca Miller / Wheat flour tortillas are the second most consumed bread product after white pan bread. Commercial tortillas are formulated with highly viscoelastic hard wheat flours selected and grown for breadmaking. However, the inherent properties of bread flours require costly formula adjustments to enhance dough extensibility necessary for tortilla production. The objective of this study was to identify the biochemical and physical factors in wheat affecting wheat tortilla quality. Six popular hard winter wheat cultivars (1863, Armour, Clara CL, Denali, Everest, Tiger) were grown in five locations in Kansas. Wheat and flour properties were characterized using approved AACCI methods. Protein composition was determined using size-exclusion high performance liquid chromatography. Flour particle size and starch granule size were measured with laser diffraction. Tortillas were made with a laboratory hot press method. Tortilla shelf-stability over 14 days, opacity, appearance, dough machinability and specific volume were measured. Data collected from flour and tortilla tests were analyzed using ANOVA and means were compared with Tukey-Kramer HSD. In general, the flours did not differ significantly in flour or tortilla properties. Regression analysis (Pearson) showed flour protein content was highly and significantly correlated with tortilla opacity (r=-0.81), L color value (r=-0.79), a color value (r=0.80), and day 14 shelf-stability (r=0.76). Flour water absorption showed highly significant correlations with tortilla opacity (r=-0.81), L color value (r=-0.79), a color value (r=0.77) and day 14 shelf-stability (r=0.73). Tortilla opacity was highly correlated with B-type starch granules (r=-0.83). This study showed that starch granule size, flour protein content and flour water absorption appeared to influence tortilla appearance. However, repeating the study with a larger and more diverse sample set is recommended.

Master of Science / Department of Food Science / Karen A. Schmidt / People who suffer from swallowing disorders are diagnosed with dyphasgia. The beverage for the dyphagia patients should have the apparent viscosity in the range of nectar-like (51 to 350 mPa•s) or honey-like (351 to 1750 mPa•s). Due to the swallowing problems, dysphagia patients usually consume beverages slowly. Thus, the apparent viscosity of beverage for such patients should be high enough to be in the suitable range during the entire time of consumption. Three ratios of α-lactalbumin (α-la)/β-lactoglobulin (β-lg) (3:8, 1:1 and 8:3) were used to prepare the milk systems. These ratio adjusted milk systems were either processed at 70, 80, and 90ºC for 30 min or at 25ºC, and cooled to 25 ± 1ºC. After the process was completed, the milk systems were set quiescently 120 min at 25 ±1ºC. Physical and chemical properties were assessed at various time. For the milk systems at 0 min, the apparent viscosity increased in all 90°C processed-samples, and the increase was in the order of 8:3 (15.96%), 1:1 (6.38%) and 3:8 (2.11%) compared with the 25ºC samples at each ratio. When the milk systems set for 120 min, apparent viscosity increased slightly by 3.7%. The maximum apparent viscosity was 2.18 mPa•s, which was less than nectar-like. Therefore, xanthan gum was added at 0.15 w/w % to enhance rheological properties of the milk systems. α-La/β-lg ratio adjusted milk systems either with or without xanthan gum were prepared, and processed at 90ºC or 25ºC, and cooled to 25 ± 1ºC. Apparent viscosity increased by 48.61 and 89.61% in 3:8 and 8:3 milk systems, respectively for those at 0.15% xanthan gum concentration and processed at 90ºC compared with at 25ºC. Apparent viscosity of 8:3 milk systems at xanthan gum concentration of 0.15% processed at 90°C was 58.7 ± 2.12 mPa•s which was within the nectar-like range. When the samples were set for 120 min, no changes were found in the apparent viscosity of the milk systems. If the rheological properties of the milk systems can be controlled by ingredients interactions, this can be used to develop nutritious products with different forms for dysphagia patients.

Master of Science / Food Science Institute / Elizabeth Boyle / Intrinsic factors impact Listeria monocytogenes growth in ready-to-eat poultry products. Sliced deli turkey was formulated with in-going concentrations of 1.5% NaCl or 0.75% NaCl/0.75% KCl, 0 ppm or 200 ppm NaNO[subscript]2, and using 10% or 45% pump for a total of 8 treatments. Turkey roasts were sliced and inoculated with a 5-strain L. monocytogenes cocktail or peptone water (control), vacuum packaged, and stored at 4[degree]C. Treatments were sampled on days 0, 7, 14, 21, 28, 42, 63, and 91 of storage to determine L. monocytogenes mean log growth and aerobic plate count (APC). The pH, water activity, residual nitrite concentration, and percent fat, moisture, protein, and sodium were measured using control treatments on each sampling day. There was a nitrite by day and a percent pump by day interaction (P<0.05) for L. monocytogenes and APC populations. Listeria monocytogenes populations in treatments containing 200 ppm NaNO[subscript]2 were 0.70 to 2.39 log CFU/cm[superscript]2 lower compared with products formulated with 0 ppm NaNO[subscript]2. Using 10% pump reduced L. monocytogenes populations by 0.62 to 1.50 log CFU/cm[superscript]2 on days 7 to 28 and at day 63 compared with 45% pump treatments. Incorporating 1.5% NaCl or 0.75% NaCl/0.75% KCl into formulations did not affect (P>0.05) L. monocytogenes populations during storage. On days 7 through 91, APC populations were 0.76 to 2.96 log CFU/cm[superscript]2 lower with inclusion of 200 ppm NaNO[subscript]2 compared to 0 ppm NaNO[subscript]2. There was a treatment by day interaction (P<0.05) for L. monocytogenes populations and APC. The initial inoculum level of L. monocytogenes averaged 2.21 log CFU/cm[superscript]2 and was similar (P>0.05) for all treatments on day 0. Listeria monocytogenes populations increased (P<0.05) from day 0 to 14 by 1.30 to 5.04 log CFU/cm[superscript]2. Overall, L. monocytogenes populations increased during storage and by day 91 L. monocytogenes populations were similar regardless of NaNO[subscript]2 level used except for treatments formulated with 0.75% NaCl/0.75% KCl and 10% pump. Listeria monocytogenes and APC populations were influenced by nitrite concentration and percent pump, while inclusion of NaCl or NaCl/KCl did not affect L. monocytogenes growth during refrigerated storage in vacuum packed sliced deli turkey.

Master of Science / Food Science Institute, Human Nutrition / Delores H. Chambers / Fresh mangoes are highly perishable, and therefore, they are often processed to extend shelf-life and facilitate exportation. Studying the transformation that mango cultivars undergo throughout processing can aid in selecting appropriate varieties for products. In the 1st part of this study, the flavor and texture properties of 4 mango cultivars available in the United States (U.S.) were analyzed. Highly trained descriptive panelists in the U.S. evaluated fresh, purée, and sorbet samples prepared from each cultivar. Purées were made by pulverizing mango flesh, passing it through a china cap, and heating it to 85 °C for 15 s. For the sorbets, purées were diluted with water (1:1), sucrose was added, and the bases were frozen in a batch ice cream freezer. Much of the texture variation among cultivars was lost after fresh samples were transformed into purées, whereas much of the flavor and texture variation among cultivars was lost once fresh mangoes and mango purées were transformed into sorbets. Compared to the other cultivars, Haden and Tommy Atkins underwent greater transformations in flavor throughout sorbet preparation, and processing reduced the intensities of some unpleasant flavors in these cultivars. Tommy Atkins was the only cultivar that had flavor differences from other cultivars when it was in sorbet. Results suggest that cultivar variation is generally not detectable in mango sorbet unless the cultivar has a distinct initial flavor. In the 2nd part of this study, descriptive panelists in Thailand evaluated the flavor and texture properties of fresh samples and purées prepared from 6 cultivars grown in Thailand. Thermal processing had unique effects on the flavor of each cultivar, especially Nam Dok Mai and Chok Anun; Nam Dok Mai significantly decreased in mango identity and peach flavors after processing, whereas Chok Anun significantly increased in sweet, mango identity, and pineapple flavors. Although a slight amount of flavor variation among cultivars was lost because of thermal processing, most of the texture variation was eliminated. Because of significant changes in flavor and texture after heat treatment of mango cultivars, manufacturers should select cultivars for mango purées based on their properties after thermal processing.

Master of Science / Department of Animal Sciences and Industry / Elizabeth A. E. Boyle / Light emitting diode (LED) and fluorescent (FLS) lighting effects on enhanced pork loin chops, beef longissimus dorsi and semimembranosus steaks, ground beef, and ground turkey displayed in two retail display cases set up with similar operational temperatures were evaluated using visual and instrumental color, Enterobacteriaceae (EB) and aerobic plate counts (APC), internal product and case temperatures, and thiobarbituric acid reactive substances (TBARS). Visual discoloration of the five meat products increased (P<0.05) as display time increased. Beef longissimus dorsi steaks, ground beef, and the superficial portion of beef semimembranosus steaks had less (P<0.05) visual discoloration under LED lighting than FLS. Compared to FLS, pork loin chops under LED lighting had higher (P<0.05) L* values and a lower (P<0.05) a/b ratio. The deep portion semimembranosus steak under LED was redder (P<0.05) and the superficial portion had a lower (P<0.05) a/b ratio; LED deep and superficial portion semimembranosus steaks had higher (P<0.05) saturation index values at 5.18 and 4.47, respectively, on d 0 than FLS. Pork chops under LED lighting had lower (P<0.05) APC populations than FLS by the end of display. Enterobacteriaceae populations fluctuated throughout display on ground turkey under FLS lighting while populations remained stable under LED. APC populations increased as display time increased for pork loin chops, ground beef and ground turkey, but not beef longissimus dorsi steaks possibly due to initial case-ready postmortem age. As display time increased, EB populations increased (P<0.05) for pork loin chops, ground beef and ground turkey. The internal temperature of all products, except beef longissimus dorsi steaks, was lower (P<0.05) in the LED case. FLS case temperatures were higher (P<0.05) by 0.56 to 1.11°C than LED over the duration of the study. Pork loin chops, ground turkey, and beef semimembranosus steaks had higher (P<0.05) TBARS values by 0.06 to 0.24 mg malonaldehyde/kg under LED lighting, but lighting type did not affect (P>0.05) lipid oxidation of beef longissimus dorsi steaks or ground beef. LED lighting results in lower display case temperatures, lower internal product temperatures, and extended color life; however, lipid oxidation was increased in some cuts under LED lighting.