In an attempt to further our understanding of the relationship between the calpain system and postmortem tenderization, three muscles [biceps femoris (BF), infraspinatus (IS), and longissimus (LD)] from normal (N = 6) and callipyge (N = 6) sheep were studied. Callipyge is a genetic phenomenon where carriers of the callipyge gene present a hypertrophy of pelvic and torso muscles, such that BF and LD are affected while IS is not. It has been observed characteristically that calpastatin and m-calpain activities are increased in muscles of animals affected by the callipyge phenotype. Soluble calpain and calpastatin, and myofibril-bound μ-calpain activities, and myofibrillar fragmentation index (MFI) were determined at death, 1d, 3d and 10d postmortem. Sarcomere length was determined at 1d and 10d postmortem. Shear force of the longissimus muscle was determined at 1d, 3d and 10d postmortem. Western blots for calpastatin, μ-calpain, desmin, nebulin, titin, troponin-T and α-actinin were performed to follow the degradation pattern of those proteins. The calpastatin and m-calpain activities were more than two-fold greater in BF and LD muscles from callipyge than in the same muscles from normal animals. Calpastatin activities in infraspinatus muscle from normal animals were higher than in the other two muscles of this phenotype. Soluble μ-calpain activities were higher at death for normal phenotype in BF and IS muscles and it decreased rapidly during postmortem storage. However, the rate of this decrease in that activity was faster in normal than in callipyge phenotype. Myofibrils contained calcium dependent protease activity and this activity was inhibited by cysteine proteases inhibitors and by calpastatin to some degree. There was no difference in the myofibril-calcium dependent protease activity between phenotypes at any time postmortem, presenting lower activity at death. The magnitude of protein degradation and tenderization were assessed by MFI and shear force, respectively. Neither the MFI nor shear force changed appreciably during storage of the callipyge affected muscles. Calpastatin level seems to determine the rate of postmortem tenderization.

<p> The western corn rootworm, or WCR, (<i>Diabrotica virgifera virgifera </i> LeConte) is the most significant pest of field corn (<i>Zea mays</i>) in the United States, and has recently expanded its range into Europe. Since 2004, hybrid corn containing Bt toxins targeting the corn rootworm complex have been heavily adopted and are now the primary control measure for this pest in North American corn production. </p><p> The evolution of resistance is an ongoing concern, and to ensure Bt products will retain their usefulness, insect resistance management (IRM) tactics using various refuge structures have been adopted. One of the key tenets of the refuge strategy is that males and females emerging from Bt and refuge plantings mate randomly. A violation of this largely untested assumption would lead to acceleration of resistance development. </p><p> To generate empirical field data on mating rates between beetles emerging from Bt and refuge plants, field cage studies using field populations of WCR in Indiana were utilized. Various refuge configurations were tested; all refuge plants were labeled using the stable isotope N15. This mark persists in the adult beetles after eclosion, allowing for collection and analysis of isotopic ratios of beetles in mating pairs. This approach was used to test the random mating assumption in Bt and refuge beetles collected from field cages. Other data collected include emergence rates, timing and sex ratios for each of the treatments. </p><p> Results indicate that mating based on natal host may not be as important of a factor as initially thought. Mixed mating occurs at a high rate when there are higher numbers of susceptible rootworms even though the measured fitness parameters between <i>Cry3Bb1</i> and refuge adults were significantly different (p&lt; 0.05). The main indication from this study is that not enough susceptible individuals are produced from a 5% refuge-in-a-bag strategy which is the dominant form of refuge planting in the United States. </p>

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3516. Adviser: Carl M. Parsons. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6121. Adviser: Peter James Garlick. Includes bibliographical references (leaves 72-89) Available on microfilm from Pro Quest Information and Learning.

Master of Science / Food Science Program / Thomas J. Herald / For the last decade in the U.S., consumers have demanded fresh, healthier convenience-type foods namely, fresh-cut vegetables. Globalization has played a major role in rapid growth of the fresh-cut industry sector. Thus, consumers may purchase their favorite seasonal vegetables in local grocery stores year-round. However, the convenience of year-round produce availability brings the potential of foodborne outbreaks. Thirty-two states reported 190 produce-associated outbreaks, 16,058 reported illnesses, 598 hospitalizations, and eight deaths from 1973 to 1997. Pathogenic bacteria contaminate raw agricultural commodities through various pathways such as irrigation with untreated water, use of noncomposted animal manure as fertilizer, and wash water systems. The increasing number of produce-related outbreaks has raised awareness to interventions that remove human pathogens on fresh produce. Washing solely with tap water cannot be relied upon to completely remove pathogens. Chlorinated water is the most frequently used sanitizer, however, reductions are less than 2.63-log CFU/g on leafy and salad vegetables. Such reductions, although significant, are not sufficient to assure the microbial safety of minimally processed vegetables. The efficacy of several other chemical agents such as chlorine dioxide, ozone, electrolyzed water, hydrogen peroxide, organic acids, and other commercial products have been evaluated as potential alternatives to chlorine.

Doctor of Philosophy / Department of Animal Sciences and Industry / J. Scott Smith / The effect of fat level and antioxidant Origanox on the formation of 2-dodecylcylobutanone (2-DCB) was investigated in fresh irradiated ground beef patties. Patties containing 15% and 25% fat were irradiated by electron beam at 1, 2, 3, and 4.5 kGy. Ground beef patties with 0.08% Origanox were gamma irradiated at 3.0 kGy. Commercially available irradiated ground beef with different fat levels was analyzed in order to estimate dose absorbed by these samples. The 2-DCB was extracted by Supercritical fluid extraction (SFE) and analyzed by gas chromatography-mass spectrometry (GC-MS). The concentration of 2-DCB increased linearly with dose with no significant difference in 2-DCB concentrations between the two fat levels. The estimated doses applied to the commercial samples ranged between 1.38 kGy and 1.55 kGy. Origanox did not affect the concentration of 2-DCB. Mutagenicity of 2-DCB was evaluated by the Ames assay using five standard Salmonella tester strains with S9 enzyme activation. The Ames assay did not show a mutagenic effect of 2-DCB, including samples incubated with S9. Acute toxicity of 2-DCB was evaluated by the Microtox acute toxicity system and compared with cyclohexanone and 2-nonenal (both GRAS additives). The toxicity of 2-DCB was between that of cyclohexanone and 2-nonenal while the maximum toxic effect elicited by 2-DCB was the least of the three compounds. Metabolism of 2-DCB was investigated in Female Sprague-Dawley rats. Hexane extracts of feces and fat were analyzed by GC-MS. Urine with and without added β-glucuronidase, was monitored for glucuronide complexes by hexane extraction GC-MS. The total amount of 2-DCB recovered in feces was 1.78 ± 0.63 mg over five days, about 3-11% of the total 2-DCB administered. The total amount recovered in fat was 0.08 ± 0.01 mg which was approximately 0.33% of the total 2-DCB administered. No metabolites were recovered in any of the urine extracts.

Doctor of Philosophy / Food Science Program / Fadi M. Aramouni / Thomas J. Herald / Dynamic viscoelastic and intrinsic viscosity properties of native xanthan, deacetylated xanthan, guar, and their mixtures in dilute solutions were investigated by using an oscillating capillary rheometer. Influence of mixing temperature, deacetylation, and salt concentration on xanthan conformation and interaction with guar were studied in order to provide additional evidence that can be used to elucidate the mechanism of the intermolecular interaction between the two biopolymers, and build up a more detailed rheological understanding of molecular interactions between xanthan and guar gum in dilute solutions. Synergistic interaction was found at mixing temperatures of 25 and 80 °C, but a stronger synergistic interaction was observed at mixing temperature of 80 °C. The differences in viscosity and elasticity measurements between the two mixing temperatures could be attributed to the degree of disordering of xanthan. For both mixing temperatures, the relative viscosity and elasticity of xanthan and guar blends were higher than the relative viscosity and elasticity calculated for blends assuming no interaction, indicating that intermolecular binding occurred between galactomannans backbone and disordered segments of xanthan. Deacetylated xanthan exhibited a stronger synergistic interaction with guar than native xanthan. The intrinsic viscosities of deacetylated xanthan-guar mixtures were higher than those calculated from the weight averages of the two individually, whereas the intrinsic viscosities of native xanthan-guar mixtures were lower than those calculated from weight averages of the two individually, demonstrating that intermolecular binding occurred between xanthan and guar gum. Synergistic interaction for both native xanthan-guar mixtures and deacetylated xanthan-guar mixtures in the dilute regime was observed in water and 2 mM NaCl but not in 40 mM NaCl. The results suggest that intermolecular interaction has occurred between xanthan and guar mixtures in water and 2 mM NaCl, but may not occur in 40 mM NaCl and mutual incompatibility may take place. These results also suggest that degree of disordering of xanthan played a critical role in xanthan-guar interaction and may explain the differences in viscosity, elasticity, and intrinsic viscosity measurements between 2 and 40 mM NaCl, and hence, the intermolecular interaction occurred between the backbone of guar gum and the disordered segments of xanthan.

Doctor of Philosophy / Food Science Program / Edgar Chambers IV / Three studies, using descriptive sensory analysis with highly trained panelists, were conducted to better understand the sensory characteristics of fresh and processed tomatoes. A “green” note often has been described as part of tomato flavor and is noted in many fruits, vegetables, grains and processed products. Thus, the first study developed a sensory lexicon for green characteristics in foods. The lexicon, consisting of 17 sensory attributes, was used to characterize sensory properties of 22 chemicals potentially associated with green odor. Green characteristics can be differentiated as green-unripe, green-peapod, green-grassy/leafy, green-viney and green-fruity. Additional attributes that are important in various green characteristics included musty/earthy, pungent, bitter, sweet and floral. Various chemicals were described as green at different concentrations. Green-grassy/leafy was the most common characterizing green attribute of many of the chemicals studied. Changing the concentrations of the chemicals resulted not only in changing the intensity of the attributes, but it also altered the sensory profile of many of the chemicals. A sensory lexicon for describing tomatoes also was developed. A variety of fresh tomatoes, processed tomatoes, and tomato-based products such as ketchup and pasta sauce were used to create the lexicon. The characteristics of tomatoes can be described using 33 aroma, flavor and texture attributes. Some characteristics were common across all or most fresh and processed tomatoes. However, reducing the number of attributes may be possible for certain studies because some attributes were appropriate only for fresh or processed tomatoes, not both. A third study determined the sensory characteristics of five tomato types, including newer and older cultivars that varied in their physical traits and primary use. The impacts of processing on the sensory quality of tomato products were investigated, with juice (minimal processing) and paste (higher level of processing) being made from the cultivars. Fresh tomatoes differed significantly because of cultivar and ripening stage differences. Fresh tomatoes differed considerably from processed tomatoes. A low processing level intensified some key aroma and flavor attributes, but differences in flavor attributed to cultivar became minimal after a higher degree of processing. Textural differences among cultivars after processing were more pronounced than flavor differences.

Doctor of Philosophy / Department of Grain Science and Industry / Sajid Alavi / Material formulation and extrusion process parameters affect the foaming process in terms of expansion, cell nucleation, and resultant foam microstructure, which, in turn, control mechanical properties. This study utilizes non-invasive x-ray microtomography (XMT), in combination with mechanical testing and novel phase transition analysis techniques, to understand these complex relationships. The first part of this study provided significant insight into the deformation mechanism of extruded cornstarch foams. Microstructure features, including average cell diameter (2.07-6.32 mm), wall thickness (0.13-0.25 mm) and number density (18-146 cm-3), were measured. Microstructure had moderate to high correlations (|r| = 0.48 - 0.81) with mechanical properties, including compression modulus (2.2-7.8 MPa), crushing stress (42-240 kPa), number of spatial ruptures (2.6-3.6 mm-1), average crushing force (22-67 N) and crispness work (6.4-22 N-mm). The second part of this study investigated the effects of formulation, using model systems comprising of cornstarch, whey protein isolate (WPI) and sucrose, on phase transition behavior, and physical, microstructure and mechanical properties of extrudates. Increase in WPI led to greater specific mechanical energy (SME) and higher extrudate expansion. WPI had a foaming effect, which increased the cell number density accompanied by decrease in average cell diameter. Increase in sucrose led to lesser SME and lower expansion of extrudates. Contrary to expectations, phase transition properties (softening temperature, Ts, and flow temperature, Tf) were not good indicators of SME. The concluding part of this study investigated glass transition and rheological properties of cornstarch at different moisture contents (18-30% wet basis) using differential scanning calorimetry (DSC), phase transition analysis (PTA) and on-line slit-die rheometry. Glass transition temperature (Tg) (31.20 - 57.55 C) of extrudates decreased as moisture content increased. Ts (42.5 - 85.6C) and Tf (109 - 136C) also followed the same trend, and exhibited high correlations (r = 0.89 and 0.86, respectively) with Tg. These parameters were good estimates of phase transition properties of the complex and heterogeneous formulations. As expected, on-line rheological parameters, including flow behavior index, n (0.0438 - 0.304) and consistency coefficient, K (10,500 - 45,700 Pa-sn-1), were functions of in-barrel moisture, and were related to phase transition properties using WLF kinetics.

Doctor of Philosophy / Department of Animal Sciences and Industry / Michael E. Dikeman / The objectives were to determine the effects of packaging and injection-enhancement on beef sensory attributes, postmortem proteolysis, and color. Muscles from USDA Select, A-maturity carcasses were fabricated into 2.54-cm steaks on d 7 postmortem. In Experiment 1, longissimus lumborum (n=14 pairs) muscles were used. Packaging treatments were: vacuum packaging (VP); 80% O2/20% CO2 (HiO2); 0.4% CO/35% CO2/64.6%N2 (ULO2CO); 0.4% CO/99.6% CO2; 0.4% CO/99.6% N2; or 0.4% CO/99.6% Ar. In Experiment 2, longissimus lumborum (n=12 pairs); semitendinosus (n=12 pairs); and triceps brachii (n=24 pairs) muscles from one carcass side were injection-enhanced or non-enhanced. Steaks were packaged into VP, HiO2, or ULO2CO MAP. Steaks packaged in HiO2 MAP were in dark storage (2°C) for 4 d and all other steaks for 14 d. Steaks were displayed under fluorescent lighting for 7 d. Trained color panelists assigned color scores. Steaks for tenderness, cooked color, and sensory were cooked to 70°C. Steaks packaged in VP or ULO2 with CO MAP had little or no discoloration. Steaks packaged in HiO2 MAP discolored faster (P < 0.05) and more (P < 0.05) than steaks in other packaging treatments. Steaks packaged in HiO2 MAP were less tender (P < 0.05) than other treatments at the end of display, but had 10 d less aging due to shorter dark storage. Steaks packaged in HiO2 had the lowest (P < 0.05) a* values for internal cooked color of all treatments and exhibited premature browning. Enhanced steaks were more tender (P < 0.05) than non-enhanced steaks. Sensory panelists found that non-enhanced steaks packaged in ULO2CO MAP or VP were more tender (P < 0.05), had more (P < 0.05) beef flavor, and had less (P < 0.05) off-flavors than steaks packaged in HiO2 MAP. Off-flavors for steaks packaged in HiO2 MAP often were described as oxidative and rancid. Enhanced steaks had more (P < 0.05) off-flavors than non-enhanced steaks. Postmortem proteolysis measured by desmin degradation was not affected (P > 0.05) by packaging. Steaks packaged in ULO2 plus CO MAP had superior color stability, tenderness, and sensory attributes compared to steaks in HiO2 MAP.