Master of Science / Department of Grain Science and Industry / Jon M. Faubion / This work investigated the relationship between flour age (days post-milling), storage condition (temperature), and the bread baking quality of whole wheat flour. A laboratory scale milling method was designed to mimic the particle size distribution of commercially milled whole wheat flours and the 100 g ‘pup’ loaf baking method was adapted for use with whole wheat doughs. Laboratory milled whole wheat flour (Karl 92) was subjected to a 21 day storage study at two storage temperatures (72 & -15 F) with quality (baking) and chemical (lipids) analyses conducted every three days. Parameters for quality analysis included: loaf weight, volume & specific volume, as well as slice area, cell number, wall thickness, cell diameter, elongation, and non-uniformity. Three lipid classes (glycolipids, phospholipids, and neutral lipids) were extracted and analyzed by TLC with quantification by computerized analysis of spot size and density. Results were analyzed by ANOVA. Analysis of the loaf quality data revealed no trends in volume or specific volume as a function of storage time or temperature, although values for some specific days were significantly different. Likewise, analysis of crumb characteristics revealed no consistent trends for either time or storage temperature. Again, values for some, but not all, parameters (area, brightness, wall thickness, cell diameter, and non-uniformity) were significantly different for specific days of the study. Analysis of lipids revealed no consistent trends for either time or storage temperature. However, values for some lipid classes (total glycolipids, free phospholipids, and total phospholipids) were significantly different for storage temperature, and values for total neutral lipids were significantly different for specific days of the study. Suggested future research opportunities include: using new crop wheat, increasing storage duration, performing WW flour lipid exchange studies, and using lipid profiling to identify and more closely track changes in individual lipid species.

Doctor of Philosophy / Department of Grain Science and Industry / Jon M. Faubion / Charles E. Walker / Anthocyanins, a group of pink to purple water-soluble flavonoids, are well known as naturally occurring pigments credited with numerous potential health benefits. However, they are sensitive to degradation by pH, light, and temperature. Blue corn (maize) is known to be high in anthocyanins (mainly cyanidin 3-glucoside). Citric and lactic acids and glucono-delta-lactone (GDL) are weak organic acids used by the food industry. Reel, convection, and impingement ovens are all used in the baking industry and they use different baking times and temperatures because they have different heat transfer coefficients. Cookies are popular snacks and might serve as a vehicle to deliver antioxidants and fiber. Preliminary tests showed that acids significantly increase the total anthocyanin content (TAC) remaining in the cookies when used at the 1.5% level (flour weight basis, fwb), then plateau up to the 6 % level. The interaction of three acids with three oven types (impingement oven 355F/4min, reel oven 400F/10min, and convection oven 360F/4min) were conducted to investigate their effects on the TAC remaining in blue corn based cookies. Cookie formula was based on AACC method 10-50D. Whole grain blue corn flour to wheat pastry flour ratio (80/20), guar gum level (1%, fwb), and water level (21.5%, fwb) were determined based on RSM analysis. All three acids affected TAC in cookie dough and final cookies by lowering their pH in the dough system. Citric acid retained the most TAC in the cookies. Cookie made with either GDL or citric acid provided larger spread, diameter, area, eccentricity, and crack ratio compared to the lactic acid. All three oven types significantly affected TAC in the cookies. The cookies baked by the convection oven contained the highest level of TAC. Oven types affected cookie spread but not diameter, area, eccentricity, brightness, or crack ratio. Cookies made with citric acid by convection retained maximum TAC (227±3.4 mg/kg). Cookies made with GDL by convection oven provided the greatest spread, crack, and eccentricity.

Master of Science / Department of Grain Science and Industry / Hulya Dogan / Viscoelastic wheat flour doughs are renowned for their ability to produce high quality aerated bread products. Dough exhibits extremely complex rheological properties which makes it capable of occluding and retaining gas cells. The ability of these bubbles to resist failure and remain stable throughout the proofing and baking process is critical to final bread structure and volume. Understanding these factors is important when creating the distinct structural and textural characteristics that consumers desire in baked products. In this study, a method was established for using X-ray microtomography (XMT) to study the microstructure of proving dough as well as bread made from three very different wheat flours. Doughs were prepared according to AACC Method 10-10B optimized straight-dough bread-making method. Sections from unproofed (0 min), underproofed (20 min) and optimally proofed (40 min) doughs were carefully cut and frozen at –80°C. Baked loaves were also prepared following standard test bake procedures. Small specimens were cut from two locations of both the proofed and baked loaves prior to microstructural analysis. A total of 96 dough and bread samples were scanned using a high resolution desktop X-ray micro-CT system Skyscan1072 (Skyscan, Belgium) consisting of an X-ray tube, an X-ray detector and a CCD-camera. X-ray images were obtained from 137 rotation views through 180° of rotation. Hundreds of reconstructed cross sectional images were analyzed using CTAn (v.1.7) software. 3-D analysis of the bubbles indicated that average dough void fractions increased dramatically over proof time from 30.9% for the unproofed dough (0 min) to 62.0% and 74.5 % for the underproofed (20 min) and optimally proofed (40 min) doughs respectively. Oven spring caused further expansion in the baked loaves which increased average void fraction to 84.3%. Gas cell size distributions were largely skewed to the right and shifted in that same direction as processing time increased. Differences in gas cell size seen among flour varieties were largely due to variations in the size of the largest cells caused by coalescence.

Doctor of Philosophy / Department of Human Nutrition / Delores H. Chambers / A green tea descriptive sensory lexicon was developed by a highly trained panel, which identified, defined, and referenced 31 flavor attributes of green tea. The attributes were categorized as “green” (asparagus, beany, Brussels sprout, celery, parsley, spinach, green beans, and green herb-like), “brown” (ashy/sooty, brown spice, burnt/scorched, nutty, and tobacco), “fruity/floral” (fruity, floral/perfumy, citrus, and fermented), “mouthfeel” (astringent and tooth-etching), “basic tastes” (overall sweet and bitter), and other attributes (almond, animalic, grain, musty/new leather, mint, seaweed, and straw-like). Using the green tea lexicon, the flavor differences that exist among a wide range of green teas (n=138) produced in various countries were determined. Roast-processed teas were mostly responsible for brown-related flavors and steam-processed teas were mostly responsible for green-related flavors. Aroma analyses of green tea showed that the concentration of volatile compounds were much lower than stated in the literature. Brown, brown-related attributes, bitterness, and astringency became stronger and green and green-related attributes become weaker as the brewing time lengthened (1, 2, 5, and 20 min) and the water temperature increased (50, 70, 95°C). The flavor characteristics of roast-processed, steam processed, or roast-steam-processed Korean green teas differed only in their characterizing green flavors. The flavor and aroma of green teas change after sequential brewings. Green teas in leaf form can be brewed four times: the first two brews providing stronger flavor and aroma characteristics whereas the third and fourth brews will provide milder flavor and aroma characteristics. The flavor and aroma change in green teas that are stored over two years were observed at 3, 6, 12, 18, and 24 months after their original packaging dates. Green tea changes minimally during the first year of storage and only slightly more during the first two years of storage. Consumer studies and descriptive evaluations were conducted to understand what green tea flavor characteristics influence US consumers' liking. Twelve green tea samples were evaluated by three consumer groups from Korea, Thailand, and the United States. The current research suggests that familiarity plays a role in tea acceptance. However, various flavor profiles may be acceptable to consumers who are familiar with other flavors of green tea.

Master of Science / Department of Animal Sciences and Industry / Melvin C. Hunt / The objective of this study was to determine the effects of Zilmax® feeding duration (7.56 g/ton Zilmax for 0, 20, 30, or 40 d) on color development and stability of crossbred beef (B) and Holstein (H) semimembranosus (SM) steaks packaged in polyvinyl chloride overwrap (PVC), high-oxygen (80% O2, 20% CO2, HiOx) modified atmosphere packaging (MAP), and low-oxygen (0.4% CO, 30% CO2, 69.6% N2, LoOx) MAP. A 7.62-cm thick portion from beef and Holstein SM muscles (n = 120 total, 30 from each feeding duration) was removed, vacuum packaged, and stored until d 21 when two, 2.54-cm thick steaks were cut, overwrapped with PVC, and placed into retail display for 0 or 3 d. On d 10, the remaining muscle of the SM was enhanced, and five, 2.54-cm thick steaks were cut and assigned to 0, 3, or 5 d (HiOx) and 0 or 9 d (LoOx) of display. Measurements taken on the deep (DSM) and superficial (SSM) portions were: pH, L*, a*, b*, hue angle, and saturation indices, initial color, display color, and discoloration. No Diet × Display Day (P > 0.05) interaction occurred for display color or discoloration scores of B steaks in PVC. On d 1, PVC 30 d H steaks were brighter (P < 0.05) than 40 d H steaks in PVC; no differences (P > 0.05) in H PVC display color due to diet occurred on d 0, 2, and 3. For steaks in HiOx, the DSM of 20 and 30 d B steaks on d 4 and the DSM of 20 d B steaks on d 5 was brighter (P < 0.05) red than 40 d Zilmax B DSM. HiOx 20 d H steaks were darker red (P < 0.05) on d 5 of display and more discolored (P < 0.05) on d 3 to 5 than HiOx H steaks from all other diet regimens. For LoOx, 30 d B steaks were brighter (P < 0.05) red than 0 or 40 d steaks on d 0 and 9 of display. The DSM and SSM of LoOx H steaks from cattle fed Zilmax tended (P > 0.05) to be brighter red than control H steaks through 9 d of display. In conclusion, both HiOx and LoOx minimized color differences due to SM muscle areas. Feeding B cattle Zilmax for 20 or 30 d yields steaks equal to or better in color traits than cattle fed 0 or 40 d when packaged in PVC, HiOx, or LoOx. H steaks in LoOx had slight benefits in color stability when cattle were fed Zilmax for any duration, whereas H steaks in PVC had color advantages with only the 20 and 30 d durations. Packaging 20 d H steaks in HiOx resulted in less desirable color characteristics than all other feeding treatments. Keywords: zilpaterol, beef, Holstein, display color, modified atmosphere packaging, semimembranosus

Master of Science / Food Science Institute, Human Nutrition / Koushik Adhikari / Oxidative deterioration is a significant contributing factor to the limited shelf life of foods containing lipids. The lipids in meats and dairy products make them susceptible to oxidation, limiting the amount of time that such products can be stored before a change in the sensory properties is evident. The use of rosemary oleoresin in meat products and fried foods has been extensively researched and used in commercialized foods. Since dry cheese and dairy products also contain lipids that are highly susceptible to oxidation, the use of a natural rosemary oleoresin may be beneficial in increasing the shelf life and sensory acceptability of these products as well. The overall objective of this report was to review the uses of a natural antioxidant, rosemary oleoresin, to inhibit oxidation and sensory changes in dairy and meat products and determine which areas need further study.

Master of Science / Food Science Institute, Grain Science and Industry / Jeffrey A. Gwirtz / There is a limited market of gluten-free beer for the 1% of the US population that is diagnosed with an autoimmune response to gluten protein known as celiac disease. Sorghum can be malted and used in the brewing process to replace malted barley, a grain toxic to celiac patients. The objective of the study was to develop an optimum brewing procedure for a gluten-free ale-style beer. Four different sorghum hybrids (82G63, 83G66, RN315, and X303) were malted and used in brewing gluten-free ale and evaluated for physical and chemical property differences. The four sorghum hybrids were characterized first as grain and then as malt using proximate analysis, single kernel characterization system (SKCS), amylose, α-amylase, and β-amylase contents. Isolated starch from unmalted and malted samples was evaluated with differential scanning calorimetry (DSC). Malt was evaluated throughout the malting process and percent nitrogen, percent moisture, 72 hr germinative energy, steep out moisture, germination-end, and malting loss were measured. Malted sorghum hybrid samples were milled into grist, and employed in a double mash, double decoction brewing process. Following the brewing process the wort was evaluated for specific gravity, Brix, pH, color and free α-amino nitrogen (FAN). Wort was also analyzed using HPLC for ethanol and glucose content. The fermented beer was analyzed for specific gravity, Brix, pH, alcohol by volume, and color. HPLC was also used to measure ethanol and glucose content. Results of analysis found that a significant difference (p=0.05) was found for the DSC data onset temperature, which ranged from 61.75 to 65.51, illustrating the difference in starch gelatinization temperature compared to other cereals. A significant difference was found in α-amylase content (p=0.05) which ranged from 0.16 to 058 in unmalted sorghum and 71.63 to 96.44 in malted sorghum. In addition, α-amylase and β-amylase contents increased during malting. HPLC analysis of wort indicated a significant difference was found in percent maltose which ranged from 1.27 to 2.81. FAN content of wort was also significantly different and ranged from 65.15 to 151.37. HPLC of beer showed a significant difference in percent ethanol and percent glucose. Percent ethanol in the final beer ranged from 3.28 to 4.17 and percent glucose range from 0.16 to 0.31. Process development evaluation indicated a gluten-free ale style beer could be successfully produced with 100% sorghum malt.

Master of Science / Food Science Institute, Diagnostic Medicine Pathobiology / Justin J. Kastner / The Department of Homeland Security recognizes the Agriculture and Food Sector as a Critical Infrastructure and Key Resource—critical to the health and wealth of the United States. When food safety (i.e., unintentional) or food defense (i.e., intentional) issues arise, those in the Agriculture and Food Sector must quickly and efficiently make decisions to ensure the safety of consumers. Decision-making is an essential element in critical infrastructure protection and response. Naturalistic decision-making (NDM) explores how people make decisions in real- world settings. Eight factors characterize the task and setting in naturalistic environments and include the following: ill-structured problems; uncertain, dynamic environments; shifting, ill-defined, or competing goals; action/feedback loops; time constraints; outcome with high stakes; multiple players; and organizational goals and norms. This thesis explores whether or not food safety and food defense educational programs incorporate methods that help professionals make good decisions. To that end, this thesis first examines the decision-making environment in responding to incidents involving food safety and food defense. Four cases involving food safety and food defense reveal the presence of all eight factors. As these factors complicate the decision-making process, this thesis then evaluates whether or not prevailing educational programs and tools aimed at preparing for food safety and food defense issues (i.e., HACCP and CARVER plus Shock) directly address the eight factors characterizing NDM settings. This is explored by “following” a hypothetical student in a food safety and food defense course. The information presented to the student was analyzed and this analysis indicates that the eight factors characterizing NDM settings were addressed albeit to varying degrees. HACCP addresses action/feedback loops, time constraints, outcome with high stakes, and multiple players. CARVER plus Shock addresses action/feedback loops, outcome with high stakes, and multiple players. While HACCP somewhat addresses ill-structured problems and organizational goals and norms, it fails to address uncertain, dynamic environments and shifting, ill-defined, or competing goals. CARVER plus Shock somewhat addresses ill-structured problems; uncertain, dynamic environments; shifting, ill-defined, or competing goals; time constraints; and organizational goals and norms. In light of this, new approaches to training are needed to fully incorporate all eight factors.

Doctor of Philosophy / Food Science Institute / Melvin C. Hunt / Several experiments were conducted to evaluate factors affecting myoglobin redox forms stability and detection of myoglobin redox forms using near infrared (NIR) spectroscopy. In experiment 1, we investigated the relationship between metmyoglobin (MMb) reduction and oxidation of malate to α-ketoglutarate with regeneration of reduced nicotinamide adenine dinucleotide (NADH) via malate dehydrogenase (MDH). Our specific objectives for this experiment were: (1) to examine the interaction of malate and MDH to reduce MMb in vitro, (2) to determine the influence of pH, temperature, NAD[superscript]+, and malate concentration on MDH enzyme activity and MMb reduction, and (3) to determine the effects of malate on NADH generation, metmyoglobin reducing activity, and color stability using beef muscles (Longissimus lumborum, Psoas major, and Semitendinosus) extracts. We observed that, nonenzymatic reduction of horse MMb in vitro in a malate-MDH-NADH system increased with increasing NAD[superscript]+ and L-malate concentrations. Our findings further confirmed that reduction of MMb in beef extract was NAD[superscript]+ and malate concentration dependent (p < 0.05). A model system was described for studying mechanisms of enzymatic reduction of metmyoglobin reduction as a means to improve meat color and the results support the hypothesis that malate can replenish NADH via MDH activity, ultimately resulting in stabilizing myoglobin redox chemistry.In experiment 2, we assessed the ability of mitochondrial and cytoplasmic malate dehydrogenase present in postrigor bovine skeletal muscle to utilize malate as fuel for NADH regeneration and MMb reduction via the malate-NAD-MMb system. Furthermore, addition of lactate to beef mitochondrial and cytoplasmic isolates was evaluated to determine if interactions between malate and lactate increased MMb reduction. Addition of malate to isolated beef mitochondrial and cytoplasmic isolates at pH 7.2 increased (p < 0.05) MMb reduction. MMb reduction resulting from the addition of malate and lactate was equal or greater than MMb reduction resulting from malate alone. The findings from this study provided evidence that mitochondria and cytoplasmic proteins isolated from beef skeletal muscles of different metabolic origin differ substantially in their enzymatic composition. Malate-MDH assisted-MMb reduction using Mitochondrial and cytoplasmic isolates from the three beef skeletal muscles exhibited substantial differences in enzymatic compositions and their ability to reduce MMb in vitro. Differences were also observed in the enzymatic characteristics of MDH-assisted-MMb among the three beef muscles. In experiment 3, we investigated the effects of three glycolytic and tricarboxylic acid cycle metabolites on myoglobin redox forms and their in influence on meat color stability. Eighteen combinations of malate (M), lactate (L), and pyruvate (P) were added to beef Longissimus lumborum, Psoas major, and Semitendinosus muscle homogenates to study their effects on metmyoglobin formation during incubation at 25 °C. Changes in surface color at 0, 2, 4, 8, and 12 hrs were evaluated using refecto-spectrophotometry [both L*a*b* and wavelengths specific for MMb]. Results from this study suggests that at 2% concentrations level of the individual metabolites (M, L, or P), the most effective metabolite at retarding MMb formation was L > M > P in the ST, and M > L > P in the PM and LL muscles. MMB was reduced most effectively with combination of metabolites where M+L > M+P > L+P. Enhancement of meat with these metabolites can effectively extend color life of postrigor meat apparently by providing more reducing conditions for myoglobin, thus increasing myoglobin redox form stability. Experiment 4 was conducted to determine how near-infrared (NIR) tissue oximeter measurements of post-rigor beef skeletal muscle relate with the more established methods of quantifying myoglobin redox states. Surface color differences were created by packaging steaks in vacuum (VAC), 80% O[subscript]2 and 20% CO[subscript]2 modified atmosphere packaging (HiOx MAP), polyvinyl chloride film overwrap (PVC), and HiOx MAP converted to PVC (HiOx-PVC) after 2 days. Changes in surface color and sub-surface pigments during display (0,2, 4, 10, and 15 days at 2 °C) were characterized by using a reflectance-spectrophotometer and a near-infrared tissue oximeter, respectively. Fiber orientation, storage, and packaging affected (p < 0.05) color, total pigment, deoxymyoglobin, and oxymyoglobin content. Tissue oximetry measurements appear to have potential for real-time monitoring of myoglobin redox forms and oxygen status of packaged meat, but fiber orientation needs to be controlled. In experiment 5, we investigated the response of frequency-domain multidistance (FDMD) NIR tissue oximetry for detecting absolute amounts of myoglobin (Mb) redox forms and their relationship to meat color stability. Four packaging formats were used to create different blends of Mb redox forms and meat colors during display. Changes in surface color and subsurface pigment forms during simulated display (0, 2, 4, and 10 d at 2 °C) were evaluated using surface reflecto-spectrophotometry (both L*a*b* and specific wavelengths) and FDMD NIR tissue oximetry. Data for both methods of direct measurement of oxymyoglobin and deoxymyoglobin were strongly related and accounted for 86 to 94% of the display variation in meat color. Indirect estimates of metmyoglobin ranged from r[superscript]2 = 59 to 85%. It appears that NIR tissue oximetry has potential as a noninvasive, rapid method for the assessment of meat color traits and may help improve our understanding of meat color chemistry in post-rigor skeletal muscle.

Master of Science / Food Science Institute, Animal Science & Industry / Daniel Y.C. Fung / The objectives of these studies were to determine the antimicrobial effects of sodium lactate (SL) and acidified calcium sulfate (ACS) on frankfurters formulated with and without lactate in the frankfurter formulation. Two studies were performed, one which mimicked home storage, and the other evaluated the effectiveness of SL (12% v/v) and ACS (12% v/v) as antimicrobial dips when used prior to and after inoculation of Listeria monocytogenes on frankfurters formulated without lactate. In the first study, five peeled frankfurters with and without lactate in the formulation were either dipped in SL or in ACS, stabilized for 30 minutes, vacuum packaged and stored for 30 days at 4°C. Controls were also prepared by dipping in 0.1% peptone. After 30 days the packages were opened and frankfurters were dip inoculated, stabilized for 30 minutes, and one frankfurter from each treatment was sampled. All other frankfurters were then placed in storage at 7°C and sampled after an additional 7, 14, and 21 days. For the second study, treatments consisted of five frankfurters that were first inoculated with a five-strain cocktail of L. monocytogenes, stabilized for 30 minutes, then dipped in SL or acidified ACS; or were first dipped in SL or ACS, stabilized for 30 minutes then dip inoculated. Controls were prepared by dip inoculating frankfurters. One frankfurter from each treatment was sampled immediately. The remaining frankfurters were vacuum packaged, stored at 4°C and sampled after 30, 60, 90, and 120 days. For both studies, on sampling days one frankfurter from each treatment was pulsified and plated on Tryptic Soy Agar (TSA) for viable cell counts and Modified Oxford Medium (MOX) for L. monocytogenes counts. The results indicated that SL dipped frankfurters had lower total aerobic counts and L. monocytogenes counts compared with ACS treatments and the controls. Use of lactate formulation in frankfurters resulted in lower bacterial counts of both natural microflora and inoculated L. monocytogenes in frankfurters after prolonged storage at 4 °C. This research indicates that sodium lactate (12% v/v) may be effective as an antimicrobial dip on frankfurters for the reduction of natural microflora and L. monocytogenes.