Master of Science / Department of Mechanical and Nuclear Engineering / Xiao J. Xin / Energy consumption due to dairy production constitutes 10% of all energy usage in the U.S. Food Industry. Improving energy efficiency in food refrigeration and freezing plays an important role in meeting the energy challenges of today. Freezing and hardening are important but energy-intensive steps in ice cream manufacturing. This thesis presents a series of models to address these issues. The first step taken to model energy consumption was to create a temperature-dependent ice cream material using empirical properties available in the literature. The homogeneous ice cream material is validated using finite element analysis (FEA) and previously published experimental findings. The validated model is then used to study the efficiency of various package configurations in the ice cream hardening process. The next step taken is to consider product quality by modeling the ice crystal size distribution (CSD) throughout the hardening process. This is achieved through the use of population balance equations (PBE). Crystal size and corresponding hardened ice cream coarseness can be predicted through the PBE model presented in this thesis. The crystallization results are validated through previous experimental study. After the hardening studies are presented, the topic of continuous freezing is discussed. The actual ice cream continuous freezing process is inherently complex, and therefore simplifying assumptions are utilized in this work. Simulation is achieved through combined computational fluid dynamics (CFD) and PBE modeling of a sucrose solution. By assuming constant fluid viscosity, a two-dimensional cross section is able to be employed by the model. The results from this thesis provide a practical advancement of previous ice cream simulations and lay the groundwork for future studies.

Doctor of Philosophy / Department of Animal Sciences and Industry / Michael E. Dikeman / Sixty cull cows were utilized to investigate the effects of feeding a single or sequence of β-adrenergic agonists (β-AA) on performance, mRNA expression, carcass traits, economics, meat palatability, and ground beef color. Treatments included: 1) concentrate fed for 74 d (C); 2) concentrate fed for 49 d then supplemented with ractopamine-HCl for 25 d (RH); 3) concentrate fed for 51 d then supplemented with zilpaterol-HCl for 20 d (ZH); 4), concentrate fed for 26 d then supplemented with RH for 25 d followed by ZH for 20 d (RH + ZH). No differences existed among treatments for performance or carcass characteristics. However, cows supplemented with ZH (ZH and RH + ZH treatments) had increased LM areas (P = 0.18) compared to control and RH cows. Sequential feeding of RH followed by ZH had no influence on β2-adrenergic receptor (AR) mRNA expression. However, β2-AR mRNA was increased (P < 0.05) in the RH and ZH treatments when RH or ZH was supplemented during the last 20 to 25 d of feeding. Myosin heavy chain (MHC) Type IIa mRNA decreased (P < 0.05) from d 24 to 51 in all cows, while MHC-IIx increased (P < 0.05) in the ZH and RH + ZH treatments during ZH supplementation. No differences were observed in ground beef color shelf-life among treatments. Effects of β-AA supplementation on meat palatability varied among muscles. Infraspinatus steaks had improved (P < 0.05) WBSF values with β-AA supplementation. Psoas major steaks from the RH + ZH treatment were rated as more tender than steaks from all other treatments. Non-enhanced LM steaks from ZH supplemented cows had higher (P = 0.12) WBSF values along with decreased (P < 0.0001) percentages of degraded desmin compared to control and RH cows. Collagen solubility of the LM was increased with ZH supplementation compared to RH and control cows. Enhancement of steaks with 0.1 M calcium lactate improved LM tenderness of β-AA supplemented cows. Implanting and feeding cull cows for 74 d, regardless of β-AA supplementation, added value by transiting cows from a “cull” cow to “white” cow market.

Master of Science / Department of Animal Sciences and Industry / Terry A. Houser / Two experiments were completed as a part of this study. The objective of the first experiment was to determine the differences in chemical characteristics of trimmings from hot processed and traditionally processed cull meat goats. Crossbred cull doe goats (n=18) were assigned to one of 3 kills days with 6 replications per day. The sides of each goat were randomly assigned to hot processed (HP) or traditionally processed (TP). HP sides were fabricated within 2 h of slaughter, ground with 2% salt and dry ice and then held at 2oC for 24h. TP sides were chilled at 2oC for 24 h prior to fabrication and grinding. After sampling, 2% salt was added to remaining trim yielding 2 treatments: traditionally processed with no salt added (TPNS) and traditionally processed with salt added (TPS). As expected, the HP treatment had a higher (P<0.0001) ultimate pH than TP and a higher water holding capacity (WHC) than TPS (P<0.002) and TPNS (P<0.001) treatments. HP and TPNS had significantly higher (P<0.0007 and P<0.0003, respectively) percent moisture than TPS. Percent fat was similar (P>0.19) for all treatments. However, TPNS had more protein (P<0.0001) than either the HP or TPS treatments. HP and TPS had decreasing L* values until d 6 when values increased significantly while TPNS decreased steadily by day. HP and TPS differed significantly from TPNS until d 6 when no significant differences were seen. For all treatments, a* values showed decreasing values until d 6. For all treatments, b* values increased until d 5. The objective of the second experiment was to investigate the viability of composting as a means for disposing of goat tissues resulting from the slaughter and fabrication process. By-products from the slaughter of cull meat goats (n=18) were assigned to 3 treatment piles: bones, offal + head (OH), and whole (bones, skull, and offal). Bones and OH piles increased in temperature, with peaks at wk 7 and wk 9, while whole piles had elevated temperatures from wk 5 to wk 9. Bone piles had statistically lower temperatures through wk 3, but were not statistically different than other treatments through the duration of the study. Whole piles had higher (P<0.0001) temperatures over the 8 wk composting period than OH and bone piles. Bone decomposition progressed over 90 d; at d 60, bones in whole piles had greater (P<0.05) decomposition than in bone piles. Similarly, skulls decomposition increased over the 90 d period. At d 60 and 90, skulls in whole piles had greater (P<0.05) decomposition than skulls in OH piles.

Master of Science / Department of Grain Science and Industry / Keith C. Behnke / The effect of tracer particle size on the accuracy of measuring retention time inside the conditioner of a pellet mill was studied. Three experiments were conducted using tracers with different particle sizes. The control retention time was calculated using the hold-up capacity method, while retention times for treatments were calculated using the pulse-input method. In addition to the previously prepared tracers, crystalline salt and powder color dye were used as tracers in this study to represent small particle tracers. In experiment one, large, medium, and small tracers were used. The treatment with large particle size was closer to the control with differences around 1.5%. Conversely, using the tracer with small particle size resulted in larger differences, approximately 18%. Two tracers were used in experiment two, resulted in 33% difference between treatment and control using a small particle size tracer, and a 10% difference using a tracer with similar particle size to the main materials. A tracer similar in particle size to the materials flowing inside the conditioner was used in the third experiment in addition to the salt and dye. Statistical analyses for this experiment indicated that particle size affects the accuracy of retention time measurements. There was a significant difference (P<0.05) in the comparison between salt and red color dye in treatment two, while there was no significant difference (P>0.05) between them in treatment one (same particle size). Moreover, in another comparison of the differences between treatments and their related controls, there was significant difference (P<0.05). However, the P-value for the red dye comparison (0.0126) was higher than that of salt (0.0026), which adds density as another influential factor that affects retention time measurement.

Master of Science / Food Science Institute, Animal Science and Industry / Daniel Y.C. Fung / Within the United States, it has been estimated that 60 deaths and 73,000 illnesses are caused by Escherichia coli O157:H7 infection annually (Gavin et al., 2004). Multiple effects have been known to occur with the onset of infection from E. coli O157:H7 in which some of these can become life-threatening. Escherichia coli O157:H7 is defined as a Shiga-toxin-producing E. coli strain (STEC). This microbial pathogen is a gram-negative bacillus organism that is motile, non-sorbitol fermenting, and β-glucuronidase negative. The infectious dose of E. coli O157:H7 can be as low as ten cells (Food and Drug Administration, 2009). Consumption of contaminated food, mainly undercooked ground beef and non or incorrectly pasteurized milk, are the primary sources of E. coli O157:H7 infection in human. Cattle, in particular, are considered chief asymptomatic reservoirs for this pathogen. Carried in their gut, feces, and milk, cattle carry this Shiga toxin-producing E. coli in ranges from 10[superscript]2 to 10[superscript]5 CFU/g. Although colonized with E. coli O157:H7, cattle and other ruminants show no adverse side effects from the pathogenic bacteria. There is also a difference in the prevalence of this pathogen between human and cattle. There has been a low incidence of illness caused by E. coli O157:H7 in humans when compared to the high prevalence of E. coli 057:H7 found in cattle and their environment. It has been discovered, through population genetic analysis, that E. coli O157:H7 and other O157:H- isolates make up a clone complex. In spite of the clonal nature of E. coli O157:H7 and other O157:H[superscript]- isolates, there are significant characteristics showing variability between the clone complex. These variability aspects can possibly account for the rapid divergence of E. coli strains including the recently discovered divergence of E. coli O157:H7 in to two separate lineages. Other possible reasons for a non-linear relationship between cattle prevalence and human infection include diversity of the Shiga Toxin-Encoding bacteriophage and receptors in cattle verses human, and finally the difference between the production of Locus of Enterocyte Effacement (LEE) in both human and cattle lineages.

Doctor of Philosophy / Food Science Institute / Edgar Chambers, IV / Three independent panels evaluated a total of 22 scents. Two panels were highly trained in sensory analysis techniques and performed descriptive analysis of the fragrances. In the third panel, 318 untrained respondents completed demographic questionnaires, personality tests, and surveys on fragrance attitudes and behaviors. They also evaluated the 22 scents: their perceptions of the fragrances’ sensory qualities and hedonic value were recorded, as well as the images and personalities they associated with these particular fragrances. Some methodological issues were tested, emphasizing the need for standardized procedures and consistency in fragrance evaluation. The use of consistent methodology in the preparation of fragrance samples is critical to accurately assess fragrance sensory properties. Additionally, consistent use of validated questionnaires constitutes an important strength for the fragrance industry: to better understand consumers, develop marketing strategies, and improve customers’ guidance and education. The interplay of individual differences with fragrance perception, whether from an attitudinal, sensorial, hedonic, or associative standpoint, appears complex. From a perceptual standpoint, sensory profiles generated by trained panels were representative of consumers’ perceptions, yet trained panelists discriminated better among fragrances and provided more detailed and actionable profiles. From an attitudinal and behavioral standpoint, demographic and psychological differences explained independent aspects of motivations and attitudes toward fragrances, but were not sufficient to fully account for the variability in attitudinal and behavioral patterns. Lastly, in terms of fragrance perception and image and personality associations, the combination of both intrinsic sensory characteristics and fragrance hedonic value was necessary to understand patterns of image and personality traits associated with fragrances. Interestingly, most findings were consistent even when individual differences in liking patterns for fragrances were taken into account. However, some specific dimensions, such as mood associations were preferred by clusters of respondents and depended upon individual differences. Although more research is needed to better understand the interrelationships among individual differences and all aspects of fragrance perception in real-life settings, this research provided valuable insights into these phenomena – insights that have direct implications, including understanding consumer perceptual processes, assessing potential influences of fragrances on social interactions, and providing strategic planning for marketing and advertising of personal fragrances.

Doctor of Philosophy / Food Science Program / Daniel Y.C. Fung / Curtis L. Kastner / This dissertation was designed to evaluate antimicrobial, quality, and shelf life effects of controlled phase carbon dioxide (CPCO2) on beef trimmings destined for ground beef. Critical parameters included pressure, temperature, exposure times, modified atmosphere conditions, and days of simulated retail display. 1500 psi CPCO2 for 15 min achieved 0.83, 0.96, 1.00, and 1.06 log reductions for Total Plate Count (TPC), Generic E. coli (GEC), E. coli O157:H7 (O157), and Salmonella spp. (SS), respectively. Bacterial reductions in ground beef and beef trimmings were similar (P≥0.05). CIE L*, a*, and b* values in raw patties showed no differences (P≥0.05) immediately after CPCO2 application on beef trimmings. Nevertheless, significant (P<0.05) interactions were found in pressure by packaging for L*, in pressure by packaging by days of simulated retail display for a*, and in packaging by days of simulated retail display for b* scores. Nevertheless, after 5 days of simulated retail display, L*, a*, and reflectance (630/580nm) ratios were similar for all treatments (P≥0.05), and b* scores were most acceptable with 1500 CPCO2 (P≥0.05), regardless of the packaging conditions. After 5 days of display, cooked patties showed similar (P≥0.05) values for crude protein (%CP) and crude fat (%CF), the extent of lipid oxidation (TBARS), was higher (P0.05) in aerobic trays than flushed packages with 100% CO2. Ground beef patties manufactured from beef trimmings treated with CPCO2scored higher values for tenderness (P0.05) than other treatments. In addition, no differences (P0.05) for juiciness, beef flavor intensity, or off flavor intensity were found between non-treated and the 1500 psi CPCO2 treated patties. Microbial control of spoilage organisms and foodborne pathogens in ground beef patties with CPCO2 application in beef trimmings was effective (0.6 to 1.2 logs). Lethality levels are comparable to other intervention strategies. Discoloration of beef trimmings after CPCO2 application may not be a concern for grinding purposes. Further packaging with 100% CO2 is viable for controlling spoilage and pathogenic microorganisms after packaging and during refrigerated storage, although discoloration of raw ground beef patties packaged with 100% CO2 may be a concern for product marketing.

Doctor of Philosophy / Department of Human Nutrition / Weiqun Wang / Wheat lignans are phenylpropane dimers linked by β-β bonds with a 1, 4-diarylbutane structure. They are biosynthesized in the cell cytoplasm through action of enzymes of the phenylpropanoid pathway. Pinoresinol lariciresinol reductase (PLR) catalyzes the final steps of biosynthesis of wheat lignans. In epidemiological and clinical investigations, studies show that high plasma lignan amounts correlate with reduced risks of breast, colon, and prostate cancers. However, in some of the studies, the results are not consistent. More consistent results are observed when animal and cell culture models are used. Our previous studies in the Wang lab demonstrated that treatment of human colon cancer cells, SW480 with lignans results in a dose and time dependent inhibition of cancer cell growth. In the first paper, we investigated direct experimental cancer preventative characteristics of a wheat lignan, secoisolariciresinol diglucoside (SDG) vs. its metabolite enterolactone in human colon cancer SW480 cells. Treatment of cancer cells with 0-40 µM SDG or enterolactone resulted into inhibition of cancer cell growth as observed by reduction of cell numbers. The reduction appeared related to induction of S-phase cell cycle arrest rather than cytotoxic effect. Further analysis revealed that SDG was more stable in cell culture medium than enterolactone. HPLC-MS/ESI showed that enterolactone is the principle metabolite in cancer cells but undetectable SDG or its metabolites were in the cells treated with SDG. In the second paper, we investigated over expression of the PLR gene and enhancement of lignan levels in transgenic wheat. We transformed wheat cultivars (‘Bobwhite’, ‘Madison’, and ‘Fielder’ respectively) with the Forsythia intermedia PLR gene under the regulatory control of the maize ubiquitin promoter. Of the total 217 transgenic wheat lines, we successfully obtained 7 transformants with the inserted ubiquitin PLR gene as screened by PCR. Real-time PCR further indicated 109-117% PLR over expression over the transgenic control in 3 transformants of the 7 at T0 generation. In addition, the levels of SDG, as determined by HPLC was found to be significantly elevated in one of the 3 positive transgenic plants. To the best of our knowledge, this is the first study reported that genetically engineered wheat with over expressed PLR enzyme enhancing phytochemical lignan has been successfully achieved.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Tiruvoor G. Nagaraja / Escherichia coli O157 is a major foodborne pathogen. The bovine gut is the primary reservoir and the organism is shed in the feces, which serves as the major source of contamination. The objectives of our research on E. coli O157 were to 1) determine prevalence and characterize presence in the rectoanal mucosa of cattle, 2) rationalize preferential prevalence in the hindgut, 3) evaluate fecal prevalence and concentration in relation to carcass contamination 4) determine the efficacy of preharvest intervention strategies to reduce fecal prevalence and/or concentration in cattle. We determined that E. coli O157 isolated from the rectoanal mucosa were similar to fecal isolates. We evaluated methods of enumeration in cattle feces to identify fecal samples with > 10[superscript3] and 10[superscript4] CFU of E. coli O157/g. We observed that prevalence of E. coli O157 on carcasses was correlated with high-shedders. We identified gluconic acid as a substrate which stimulates growth of E. coli O157 in fermentations with ruminal microbial or fecal microbial inocula from cattle. This may explain the preference to persist or colonize the hindgut because gluconic acid is a component of colonic mucin. Additionally, we evaluated the effects of cattle diets (two grain types and two grain processing methods), which present different amounts of fermentable starch to the hindgut, on prevalence of E. coli O157. Dry-rolled grain-based diets reduced prevalence of E. coli O157, possibly because of increased flow of starch to the hindgut. Competitive exclusion cultures of E. coli in in vitro fermentations reduced E. coli O157 in ruminal microbial inoculum, but in fecal microbial inoculum cultures were only efficacious when gluconic acid also was added. Lastly, we evaluated a vaccine which targeted the siderophore receptor/porin proteins of E. coli O157. The vaccine reduced prevalence, the total number of days cattle tested positive, and the total number of days cattle were identified as high-shedders of E. coli O157. In summary, our research adds further knowledge to the literature about E. coli O157 in the hindgut, provides methods to identify high-shedding animals, demonstrates the importance of high-shedding animals, and offers information about potential preharvest interventions.

Master of Science / Department of Grain Science and Industry / David L. Wetzel / During germination, biochemical changes occur in the wheat kernel by stimulation of enzymes and hormones, and the seed reserves are mobilized. Infrared microspectroscopy and imaging enables a localized chemical inventory, upon germination, to study the process. Frozen sections of germinated wheat mounted onto BaF[subscript]2 were mapped to produce functional group images for comparison with corresponding sections of ungerminated kernels. Relative functional group populations in the scutellum and embryonic axis were assessed before and after germination. An average 23% reduction in lipid to protein ratio was observed in the scutellum based on the comparison of 53,733 spectra. As a result of the early germination process, lipid in the scutellum was depleted to provide energy for the growing embryo. Germination of the kernels while in the field before harvest due to high humidity is known as preharvest sprouting. Preharvest sprouting has detrimental effects on the end use quality of the wheat (sprout damage) and cause economic loses. Tolerance to preharvest sprouting is highly desirable. To assist breeding program, a nondestructive near-IR chemical imaging method has been developed to test new lines for resistance to preharvest sprouting. The higher sensitivity of subsurface chemical imaging, compared with visual detection, alpha amylase determination, or viscosity testing, permits germination detection at early stages. A near-IR chemical imaging system with an InGaAs focal plane array (FPA) detector in the 1100 nm-1700 nm range was used. Kernels from six different cultivars, including HRW and HWW wheat, were exposed to moist conditions for 6, 12, 24, 36, and 48 hours. Images of each 90 kernel group were examined; kernels exposed to moisture for 36 hours were compared with kernels treated for 3 hours as a control. Each kernel was classified as sprouted or not sprouted with the criteria of log 1/R intensity at select wavelengths or select factors of principle component analysis (PCA) treatment of reflectance intensity data. Imaging wavelength range was expanded beyond 1700 nm to 2400 nm with the use of InSb FPA. Study for the potential for unsupervised determination in nondestructive near-IR imaging with detection wavelengths 1200-2400 is ongoing. Some preliminary results presented are encouraging.