College of Agriculture & Natural Resources
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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item COMBINED EFFECTS OF SUNLIGHT AND TITANIUM DIOXIDE NANOPARTICLES ON DIETARY ANTIOXIDANTS AND FOOD COLORS(2014) Li, Meng; Lo, Yangming M; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The breakthroughs in material science have enabled industrialized fabrication and production of nanomaterials. To date, nanoscale materials have been shown to exhibit improved functionalities, providing numerous novel applications. Titanium dioxide (TiO2) nanomaterials have been widely utilized in the food industry due to their unique properties under light. Upon light irradiation, TiO2 nanoparticles (NPs) generate highly active reactive oxygen species (ROS) therefore can be potentially used as light tunable antibacterial packaging materials. Moreover, it has also been reported that a considerable amounts of TiO2 NPs is found as an ingredient in food, cosmetics, personal care, and pharmaceutical products. With improved photoactivity, nano TiO2 generates higher amounts of ROS upon light irradiation that can result in oxidative damage. The present study investigates the combined effect of sunlight irradiation and TiO2 nanoparticles (NPs) on sensitive antioxidants and food colors. Upon simulated sunlight irradiation, TiO2 NPs weakened the radical scavenging ability of antioxidants by photocatalytic decomposition or surface adsorption. The decomposition of a widely used food azo dye FD&C Yellow No. 5 (tartrazine) by sunlight activated TiO2 NPs was also investigated. The mechanism is pH dependent, involving the depletion of two main ROS species, hydroxyl radical and singlet oxygen. Compared with the photocatalyst TiO2 sample P25, food-grade TiO2 NPs also showed strong ROS promoting ability and resulted in the degradation of selected synthetic dyes, including tartrazine, allura red and sunset yellow, as well as the semi-synthetic food color chlorophyllin sodium copper salt. Thus, TiO2 NPs should be used with caution when added to or used in contact with food ingredients that depend solely on the existing antioxidants and colors in the system. The ability of TiO2 to generate ROS was found to be phase-dependent. The rutile phase TiO2 generated the least amount of ROS when compared to anatase phase and did not lead to noticeable color degradation in the studied light irradiation period. Thus, when possible, rutile phase TiO2 should be used in food as it provides a more stable system compared to anatase and mixed phases. The results in this study provide clear insights on setting up proper protocols for evaluating and administrating nanosized TiO2 in food uses.Item QUANTIFICATION OF IONOPHORE ANTIMICROBIALS ASSOCIATED WITH POULTRY LITTER AND THEIR DYNAMICS IN THE SOILS OF THE MID-ATLANTIC USA(2014) Biswas, Saptashati; McGrath, Joshua M; Sapkota, Amir; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Anticoccidants, biochemically known as ionophores are added to poultry feed for growth promotion, prophylactic and therapeutic purposes to better sorb nutrients and against coccidiosis caused by parasite Eimeria sp. Ionophores belong to the class of emerging contaminants, as they are not regularly monitored in the environment and not specifically treated in the effluents. Potentially, this can cause ionophores to enter into the environment freely. There is little information regarding the dynamics of ionophores in the environment. This has been related to the lack of reliable, sensitive and robust methods that can measure their trace levels from complex environmental matrices like soil, natural water and animal manure. Studies show ionophore toxicity exhibited in flora and fauna, even reported in humans above the dose of 1 mg kg-1. Hence accumulation of ionophores in the environmental can be detrimental. Our multi-scale investigation of ionophores involved, a) method development for trace analysis of ionophores in poultry manure using liquid chromatography triple quadrupole mass spectrometry (HPLC-–MS/MS), b) batch equilibrium studies of ionophores using soils from mid-Atlantic region of the USA and c) influence of soil physico-chemical parameters on dynamics of ionophores in soil-water systems. Our HPLC-–MS/MS method was successful in quantifying ionophores ranging from (19.19 ±± 6.6) µg kg-1 to (97.86 ±± 19.19) µg kg-1 with concentrations of monensin being the highest. This method was further used to investigate partitioning of monensin in soil-ndash;water systems relevant to the occurrence of ionophores in the natural environment. Sorption and desorption isotherms were developed and influence of soil physico-chemical parameters on the sorption-desorption processes were analyzed. C-–type linear isotherms were generated with partition coefficients ranging from (6.41±± 1.34) to (343.83 ±± 5.68) LKg-1. Soil parameters such as cation exchange capacities, pH, organic matter, sand and silt content were found to correlate with sorption in different conditions. A major focus of this dissertation was to develop novel methodologies and design experiments to execute our research objectives.Item HEXAVALENT CHROMIUM QUANTIFICATION AND REMEDIATION IN SOILS AND WASTE MATERIALS(2014) DeSarle, Catherine Rose; James, Bruce R; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Hexavalent chromium (Cr(VI)) is a carcinogen and a pollutant of soils and natural waters. The standard method to extract and quantify total Cr(VI) in soils and waste materials was modified to prevent method-induced reduction of Cr(VI) by not heating (95°C) but shaking (100 cycles/min) at 23°C, followed by quantification using the 1,5-diphenylcarbazide method or ion chromatography. Forms of carbon and Cr(VI) (mineralogical vs. soluble) significantly influenced method-induced reduction. The proposed method should be used with samples containing ≥ 10 g/kg organic C. The new method was used to study the reduction of Cr(VI) in soils with Fe(II), Fe(III), and organic carbon, and the Cr in remediated soils was fractionated. Fe(II) in combination with Fe(III) was the most effective at reducing Cr(VI) and immobilizing newly-reduced Cr(III). The extraction and quantification refinements are relevant to accurate and precise metrics for Cr(VI) and its remediation in soils.Item CHROMIUM OXIDATION-REDUCTION CHEMISTRY CONTROLLED BY IRON AND MANGANESE (HYDR)OXIDE SURFACES AND SOILS: COLUMN LEACHING AND SPECTROSCOPIC STUDIES(2014) Miller, Christina Langlois; James, Bruce R; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Soil interfaces, including those defined by horizons and iron (Fe(III)) and manganese (Mn(III,IV)) (hydr)oxide mineral surfaces, are a largely unstudied area in soils research, especially in terms of their oxidation-reduction properties. This study attempted to address two questions related to this research deficiency. The first: how chromium (Cr) redox changes throughout mineralogically different soil horizons, and the second: how Cr redox structurally alters Fe(III) and Mn(III,IV) (hydr)oxides in synthetic, soil, and microbial systems. Both parts of the study used column leaching experiments along with Cr speciation techniques to study simulated soil horizon interfaces and Fe/Cr and Mn/Cr redox systems. X-ray absorption spectroscopic techniques were also utilized to analyze the mineral structure of Fe(III) and Mn(III,IV) (hydr)oxides. The results of the study indicate that there are significant interfacial properties affecting Cr(VI) reduction and that Cr(III) oxidation does change the mineral structures of synthetic, soil, and fungal Mn(III,IV)(hydr)oxides to varying degrees.Item Promotion of Value-Added Uses of Soybeans(2011) Slavin, Margaret; Yu, Liangli; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Soybeans contain a wealth of health-promoting phytochemicals, the amounts of which are known to vary considerably across genotypes and growing conditions. The present work is dedicated to better understand these variations and to improve the methods for investigating soy phytochemicals. To address the first of these concerns, low-linolenic soybeans and colored seed coat soybeans were investigated for their health beneficial components, as well as their chemical and biological properties. A study of low-linolenic soybeans showed their similar antioxidant activity, total phenolics, and isoflavones to normal fatty acid soybeans. The potential for a different trend in tocopherols and lutein was observed between low-linolenic and regular fatty acid soybeans, but the limited study size prevented a definitive conclusion. This work was the basis for further studies on low-linolenic soybeans not included in this report. Subsequently, a study of eighteen soybeans of brown, green, yellow and black seed coat colors concluded that black seed coat soybeans had significantly higher scavenging activity against hydroxyl, peroxyl, and ABTS+ radicals. Black seed coat soybeans also contained higher total phenolic contents and isoflavones than the other colored soybeans, and were the only color to contain the anthocyanin cyanidin-3-glucoside. However, when soybean extracts were tested for their ability to prevent colon cancer cell proliferation, seed coat color and chemical composition were not necessarily predictive of an extracts' bioactivity. Lastly, a new analytical method was developed and validated for quantification of phytosterols, tocopherols and carotenoids, three separate classes of soy lipophilic phytochemicals, in a single extraction and HPLC run. A ternary, isocratic solvent system of acetonitrile, methanol and water (48:22.5:29.5, v/v/v) was used to achieve separation on a phenyl column. Evaporative light scattering detection (ELSD) was used to quantify beta-sitosterol, stigmasterol, campesterol, alpha-, delta- and gamma- tocopherols, while lutein was quantified with visible light absorption at 450 nm. This method offers a more efficient alternative to separate, individual methods for quantifying lutein, tocopherols and sterols in soybeans.