Randomized complete block designs with three replications were utilized to evaluate the effects of fumigation with sulfuryl fluoride (SF) (0, 12, 24, 36 and 72 mg/L), phosphine (PH3) (0, 200 and 1000 ppm at 48 hr), methyl bromide (MB) (0, 4, 8, 16, and 32 mg/L for 48 hr), carbon dioxide (CO2) (0, 60% at 48 hr and 60% at 96 hr) and ozone (O3) (0 ppm and 175 ppm for 48 hr) on the volatile flavor compound concentrations in dry cured ham. Fluoride and SF concentrations increased (P < 0.05) in dry cured hams as SF fumigation concentration increased, but all samples contained fluoride and SF concentrations below the legal limits of 20 and 0.01 ppm, respectively. Also, as phosphine fumigation concentration increased, the residual concentration of phosphine also increased in the hams (P < 0.05), but all samples contained levels that were lower than the legal limit of phosphine in stored food products (0.01 ppm). Minimal differences existed in the presence and concentration of aroma active compounds in fumigated hams when compared to the control. Triangle tests indicated that consumers could not discern (P > 0.75) between the control hams and the fumigated hams. This study revealed that there were minimal aroma/flavor differences among control hams and hams that were fumigated with SF, PH3, MB, CO2 or O3 and that fumigation of dry cured ham with SF and PH3 were safe and met legal requirements for consumption. This reveals that SF, PH3, CO2 and O3 could be tested at the industrial level to determine their efficacy as potential alternatives to methyl bromide to treat dry cured hams for insect pests.

No description available.

Flue-cured tobacco (Nicotiana tabacum L.) is an intensively cultivated crop that typically receives four to eight primary tillage passes before being transplanted on a raised row-ridge. Strip-tillage, a conservation tillage system that only requires tilling a small strip before transplanting, has been shown to be effective for tobacco producers in southside Virginia. The cost of fertilizer in recent years and the loss of applied nutrients has brought new attention to the impact of cover crops used in conservation tillage on the nitrogen fertilization of tobacco. A two-year study conducted at the Southern Piedmont Agricultural Research and Extension Center evaluated a strip-tillage production system on agronomic performance of flue-cured tobacco and evaluated the impact of cover crop management on soil nitrogen cycling and nitrogen uptake by plants. Treatments evaluated whether a wheat cover crop was broadcast or strip killed, topdressing a wheat cover crop with 0, 22, or 45 kg ha-1, and tobacco fertilization rates. Additional treatments included a soybean residue treatment, and a conventional tillage control. Topdressing wheat with nitrogen resulted in nitrogen being released late in the growing season. Whether a wheat cover crop was strip or broadcast killed had no effect on yield or cured leaf quality. Soybean residue did not provide adequate soil cover, but was shown to be a suitable ground cover option for tobacco production. Wheat not topdressed with nitrogen and tobacco receiving normal fertilization had adequate soil surface residue cover, good cured leaf quality, and yields that were comparable to those of conventional tillage. / Master of Science

The curing of flue-cured tobacco (Nicotiana tabacum L.) is an energy intensive process and represents a significant portion of the overall cost of production. Given the goal of the industry to reduce the environmental footprint of tobacco production and the energy demand of curing, attention has been directed to explore options for the use of renewable fuels for heating tobacco barns. A two-year study conducted at the Virginia Tech Southern Piedmont Center evaluated the effectiveness and cost of curing flue-cured tobacco with a wood pellet burner. Additionally, field studies were conducted to evaluate the feasibility of on-farm production of biomass fuel crops as well as on-farm manufacture of biomass fuel pellets. The first time use of a wood pellet burner with an air-to-air heat exchanger in a bulk curing barn proved to be a viable alternative to a conventional propane fueled burner. Curing cost averaged $0.05 with the pellet burner compared to $0.04 per kilogram of tobacco with the propane burner. The increase in cost was offset by a 90 percent reduction of CO2 emissions with the use of wood pellets. The use of low lignin grass varieties did have an impact on biomass pellet properties. Pellet testing revealed high ash and chloride levels which could be problematic using a high efficiency wood pellet burner. Full maturity harvest of annual grasses fertilized with 112 kg per ha N resulted in higher yields. However, fertilizing for maximum yield would increase the CO2 footprint for biomass fuel pellet production. / Master of Science / Curing flue-cured tobacco (Nicotiana tabacum L.) is an energy intensive process consuming large quantities of both propane and electricity and represents the second highest overall production cost. The tobacco as a whole has a goal to reduce the environmental footprint of tobacco production and the energy demand of curing. In order to produce the crop more sustainably, attention has been directed to explore options for the use of renewable fuels for heating tobacco barns. Currently utilizing renewable fuels is limited to a small number of wood-fired hot water boiler systems. A two-year study conducted at the Virginia Tech Southern Piedmont Center evaluated the effectiveness and cost of curing flue-cured tobacco with a wood pellet burner. Additionally, field studies were conducted to evaluate the feasibility of on-farm production of biomass fuel crops as well as on-farm manufacture of biomass fuel pellets. The first time use of a wood pellet burner with an air-to-air heat exchanger in a bulk curing barn proved to be a viable alternative to a conventional propane fueled burner. The wood pellet burner with air-to-air heat exchanger was compared to a high efficiency prototype propane burner. Curing cost averaged $0.05 with the pellet burner compared to $0.04 per kilogram of tobacco with the propane burner. The increase in cost was offset by a 90 percent reduction of CO₂ emissions with the use of wood pellets. Curing cost with the wood pellet burner is expected to be lower than that of a more traditional propane burner and curing barn. The use of low lignin grass varieties did have an impact on biomass pellet properties, however more replications testing on-farm produced pellets is necessary in order strengthen the validity of these results. Pellet testing revealed high ash and chloride levels in on-farm produced biomass pellets which could be problematic using a high efficiency wood pellet burner, but may be less precarious if paired with a more rudimentary burner. Full maturity harvest of summer annual grasses fertilized with 112 kg per ha N resulted in higher yields. However, fertilizing for maximum yield would increase the CO₂ footprint for biomass fuel pellet production. Based on these results, purchasing commercially made, readily available wood pellets is the best alternative to using a renewable fuel to cure flue-cured tobacco. This practice would allow growers to incrementally adopt the use of a renewable fuel while providing comparable operation ease as traditional propane burners.

Le coproduit de fabrication de jambon sec est issu de l'opération de désossage de la cuisse de porc parée, salée, séchée et affinée. Il est constitué à plus de 85 % d'os et de tissus associés (cartilages, ligaments, tendons). Le concassage au broyeur à marteau permet d'homogénéiser le coproduit en morceaux de taille inférieure à 8 cm (> 90 % compris entre 40 et 80 mm). La composition chimique de la matière sèche du mélange (77 ± 3 % de MS) est de 33 ± 5 % en protéines (89 % de collagène, 14 % de protéines hydrosolubles, 6 % d'acide aminés libres), 31 ± 3 % en lipides (triglycérides : 70 % ; diglycérides : 3,5 % ; acides gras libres : 11 % ; saturé/insaturé : 0,87 ; 24 % C16 :0 ; 13 % C18 :0 ; 2 % C16 :1 ; 38 % C18 :1 ; 4 % C18 :2) et 26 ± 4 % de matière minérale (phosphate de calcium 88 % ; NaCl 9 %). L'extraction aqueuse des lipides et des protéines du coproduit est étudiée en contacteur agité. Le raffinat solide est séparé par filtration à chaud sous forme de granulat et la matière grasse entraînée est séparée par décantation à froid. L'étude de l'influence des principaux facteurs de l'extraction liquide/solide (temps de contact : 30 à 90 min, température : 40 à 90°C ; ratio eau/coproduit : 4 à 10) grâce à la réalisation d'un plan d'expérience met en évidence les effets de la solubilisation et la coagulation des protéines sur l'entraînement des lipides et leur décantation sous forme de matière grasse. Mis en oeuvre à l'échelle pilote (64 kg de coproduit de jambon sec concassé, 207 kg d'eau, 30 min à 90°C en contacteur agité), le procédé de fractionnement aqueux conduit par filtration centrifuge et séchage à un granulat stable (rendement : 59 % ; matière minérale : 41 % ; protéines : 43 % ; lipides : 16 %), source de phosphate de calcium (95 % de la matière minérale) et de gélatine ou de colle d'os (88 % de protéines de nature collagénique). La fraction matière grasse décantée (rendement : 24 % ; lipides : 93 % ; triglycérides : 75 % ; diglycérides : 4 % ; acides gras libres : 7 % ; saturé/insaturé : 0,82 % ; 37 % C16 :0 ; 15 % C18 :0 ; 2 % C16 :1 ; 44 % C18 :1 ; 8 % C18 :2) présente les mêmes caractéristiques physicochimiques que le saindoux, avec une odeur proche de celle du jambon sec (19 COV aromatiques identifiés présents dans les arômes majoritaires de jambon). La fraction protéines solubilisées, obtenue sous forme de lyophilisat après concentration de la phase aqueuse (rendement : 8 % ; protéines : 52 % dont 29 % d'acides aminés libres ; matière minérale : 29 % dont 90 % NaCl, lipides : 3 %), contient aussi des glucosaminoglycanes sulfatés (GAGs : 3,4 %). Ces caractéristiques de composition, associées à ses propriétés épaississantes et gélifiantes, adhésives et stabilisantes d'émulsion, font de cette fraction minoritaire du procédé de fractionnement aqueux du coproduit de jambon sec, un extrait aux multiples applications à forte valeur ajoutée (source de peptones pour la culture de champignons et de levures, adhésif et liant naturel, ingrédient de formulation alimentaire nutracétique et cosmétique). / The ham production by-product comes from the deboning of dressed, salted, dried and refined pork leg. It consists of more than 85% of bone and associated tissues (cartilage, ligaments, tendons). Hammer mill crushing allows homogenizing the by-product into pieces smaller than 8 cm (> 90% between 40 and 80 mm).Dry matter chemical composition of the blend; (77 ± 3% DM) is 33 ± 5% protein (89% collagen, 14% of watersoluble proteins, 6% free amino acid), 31 ± 3% lipids (triglycerides: 70% diglycerides: 3.5%; free fatty acids: 11%; saturated / unsaturated: 0.87; 24% C16: 0; 13% C18: 0; 2% C16: 1; 38% C18: 1; 4% C18: 2) and 26 ± 4% mineral matter (calcium phosphate 88%, 9% NaCl). Lipids and proteins aqueous extraction of the by-product is studied in an agitated contactor reactor. The solid raffinate was separated by hot filtration to an aggregate and the fat is separated by cold decantation.The study of the influence of main factors of the liquid / solid extraction (contact time: 30 to 90 min, temperature: 40 to 90 °C; ratio water / by-product: 4 to 10) through the implementation of an experimental design, highlights the effects of proteins dissolution and coagulation on lipid output and decantation as fat matter.By pilot scale implementation (64 kg of crushed by-product of dry-cured ham, 207 kg of water, 30 min at 90 ° C in agitated contactor), the aqueous fractionation process leads, by centrifugal filtration and drying, to a stable aggregate (yield: 59%; mineral matter: 41%; protein 43%; lipids: 16%), source of calcium phosphate (95% of the mineral) and gelatin or bone glue (88% collagenous protein).The decanted fat fraction (yield: 24%; lipids: 93%; triglycerides: 75%; diglycerides: 4% free fatty acids: 7%; saturated / unsaturated: 0.82%; 37% C16: 0; 15% C18: 0; 2% C16: 1; 44% C18: 1; 8% C18: 2) has the same physicochemical characteristics as lard, with an odor similar to that of dry-cured ham (19 identified aromatic VOC part of ham main flavors). The solubilized protein fraction, obtained as a lyophilized extract after concentration of the aqueous phase (yield: 8%; protein: 52% with 29% of free amino acids; mineral matter: 29%, with 90% NaCl, lipids: 3%), also contains sulfated glycosaminoglycans (GAGs: 3.4%). These composition characteristics, associated with its thickening and gelling properties, adhesive and stabilizing for emulsion, transforms this minor fraction of the aqueous fractionation process of the dry-cured ham byproduct, in an high added value multiple applications extract (source of peptones for culture for fungi and yeasts, a natural and binding adhesive, ingredient for food nutraceutic and cosmetic formulation).

Doctor of Philosophy / Department of Entomology / Thomas W. Phillips / Robert "Jeff" J. Whitworth / Dry-cured ham is protected from infestations of Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) with the fumigant methyl bromide. Developing feasible alternatives to methyl bromide is necessary due to the phase out of methyl bromide. The effectiveness of food-safe compounds for preventing infestations of T. putrescentiae on dry-cured hams was evaluated by dipping ham pieces in solutions of various food additives. Propylene glycol (1, 2-propanediol), lard, ethoxyquin and butylated hydroxytoluene prevented or significantly reduced mite population growth. A combination of carrageenan + propylene glycol alginate + 40% propylene glycol was effective in reducing mite numbers on treated whole-aged hams compared with untreated hams. Dose/response tests with twelve registered residual insecticides were conducted to assess contact toxicity to T. putrescentiae. Three of these insecticides were evaluated for persistence over a 2-month period on different surfaces. Commercial formulations of deltamethrin plus chlorpyrifos-methyl, chlorfenapyr, and malathion showed promising results for contact toxicity against T. putriscentiae. Chlorfenapyr applied to metal, concrete, and wood resulted in 100% mortality of treated ham mites for up to 8 weeks. The effect of high and low temperatures on mortality of T. putrescentiae was studied in the laboratory. Groups of 10 eggs and groups of a mixture of 40 adults and nymphs were separately exposed to several high and low temperatures, ranging from +35 to 45°C and from −20 to +5°C, for several time periods. Eggs were found to be more tolerant to both high and low temperatures compared with adults and nymphs. Results showed that high temperatures from 40-45°C killed all T. putrescentiae eggs, adults, and nymphs within 4-1 d, while −10°C or lower killed all the same stages in less than 1 d. Combinations of the fumigant sulfuryl fluoride (SF) applied under high temperatures ranging from 25-40ºC, were studied to determine the highest temperature, shortest exposure time, and the lowest value of a concentration-by-time product (CTP) of SF against T. putrescentiae. Results showed that complete control of all life stages of T. putrescentiae was achieved at 40ºC with SF. More than one day of exposure was required to kill adults and nymphs and eggs at 40ºC at a CTP close to the EPA labeled rate of 1500 gh.m⁻³. Results indicated that adults and nymphs were more susceptible to SF compared to eggs. This study focused on investigating different control methods for T. putrescentiae in dry-cured ham facilities and most of examined techniques are preventive, although some of them can be applied as remedial methods after mite infestations are noticed.

Nitric oxide (NO) and carbon monoxide (CO) gases, alone or with oxalate, phytate, or ethylenediaminetetraacetate (EDTA) were tested for antibotulinal activity as substitutes for sodium nitrite in ground pork inoculated with spores of Clostridium botulinum, then abused by storage at 277°C. Nitric oxide with 250 ppm oxalate or phytate was most inhibitory, while NO alone was as effective as 156 ppm sodium nitrite for inhibition of gas and botulinal toxin production in the meat system. All swollen samples contained very low levels of residual nitrite, but nitroso heme and soluble iron content did not change compared with unswollen samples of the same treatment while total heme content decreased slightly. Binding iron in the meat system did not appear to be sufficient for botulinal inhibition. Apparently, residual nitrite must be present to react directly with the botulinal cell, inhibiting growth. NO gas would not be a practical subsitute for sodium nitrite in curing, since nitrite itself is formed when meat is blended in the presence of this gas. Neither could CO be used in meat curing, since the pink color of raw, CO-treated meat disappeared after cooking. More importantly, all samples treated with CO swelled rapidly and contained botulinal toxin.

Although nitrite is a known inhibitor of Clostridium botulinum in cured meats, the mechanism of inhibition is not understood. The observation has been made that iron is required for growth of C. botulinum and that the role of nitrite may be to alter the pathway of iron uptake by these organisms. Since the color change in cured meats is due to the binding of nitrite to the heme group of meat pigments, it was hypothesized that nitrite may also be tying up an essential iron source, heme. This experiment was an investigation of the possibility that myoglobin added to a meat system would stimulate growth and toxin production by C. botulinum much more than myoglobin that had been nitrosylated before inclusion in the product. Treatments were included to compare the effects of a heme iron source, myoglobin, with that of an ionic source, ferric chloride. To help understand the role of free iron in botulinal growth, several treatments contained a metal ion chlator, ethylenediaminetetraacetic acid (EDTA). Nitrite caused a definite delay of growth, as evidenced by gas bubbles, when compared with a non-nitrite system. Addition of ferric chloride resulted in an increase in the rate of of appearance of swollen samples, although growth was enhanced even more when myoglobin was added. When nitrosylated myoglobin was included, growth was inhibited more than in the treatment with nitrite alone. EDTA inhibited growth of C. botulinum but a conclusion should not be made with respect to the chelation of iron since EDTA chelates many other metals. Residual nitrite levels had declined to below 10 ppm by the time swelling occurred. Although swelling did not occur until nitrite had declined in the products, the absence of nitrite alone did not allow growth and toxin production. Since nitrosylated myoglobin and EDTA inhibited botulinal growth even after residual nitrite had declined, it is possible that the inhibitory action of nitrite is creating a nutritional deficiency for C. botulinum.

In this study structural design, analysis and composite manufacturing applications for a tactical UAV, which was designed and manufactured in Aerospace Engineering Department of Middle East Technical University (METU), is introduced. In order to make an accurate structural analysis, the material and loading is modeled properly. Computational fluid dynamics (CFD) was used to determine the 3D pressure distribution around the wing and then the nodal forces were exported into the finite element program by means of interpolation from CFD mesh to finite element mesh. Composite materials which are mainly used in METU TUAV are woven fabrics which are wetted with epoxy resin during manufacturing. In order to find the elastic constants of the woven fabric composites, a FORTRAN code is written which utilizes point-wise lamination theory. After the aerodynamic load calculation and material characterization steps, linear static and dynamic analysis of the METU TUAV&rsquo / s wing is performed and approximate torsional divergence speed is calculated based on a simplified approach. Lastly, co-cured composite manufacturing of a multi-cell box structure is explained and a co-cured multi-cell box beam is manufactured.

The purpose of this study was to determine the cementitious parameters and placement temperature that impact internal sulfate attack in concrete. Concrete structures make up a large percentage of the infrastructure and multifamily housing. Durability is very important. Cements can be formulated to reduce the impact of external environmental exposure such as high salinity from marine environments or high sulfate levels from soils or surface waters. Concrete is also subject to internal attack such as alkali aggregate reaction, (AAR), and delayed ettringite formation, (DEF). This study focused on some of the cement chemistry issues that determine susceptibility of cement to DEF. Expansion due to DEF can weaken the concrete matrix resulting in microcracks that in some cases may progress to severe matrix cracking. The end result is loss of load carrying capacity and costly repairs. In this study, mortar bars were made with the as received cement chemistry and using additions of sulfate, and alkalis. The bars were then heat cured at various temperatures and stored in a saturated lime solution at room temperature. Measurements were made at predetermined time intervals. The series of mixes were made to determine the effect of varying sulfate levels, heat curing temperature, and alkali content in order to isolate the effect of these constituents. The cements were selected on the basis of tricalcium aluminate, alkali content, sulfate levels, C3S levels and fineness. The results indicate that a relationship exists between the rate and level of expansion experienced by the mortar bars and cementitious parameters, namely, alkali content, sulfate content, C3S levels and heat curing temperature.