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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

Effects of Processing and Packaging Modifications on the Quality and Shelf Life in Meats

Khan, Abdulla 01 May 2014 (has links)
Shelf life of meat and meat products depends on the quality of meat and packaging stability. Meat color change, lipid oxidation, pH, and microbial contamination are the main causes that affect the nutritional, sensory, and physical characteristics by forming toxic compounds, off flavors, off odors, and undesirable color. The first objective of this study was to examine the effect of newly developed CO2 generating absorbent pads on beef, tuna and chicken meats. The second objective was to compare the effect of Type I (radical quenching) antioxidants eugenol and rosmarinic acid (RA) to that of Type II (metal chelating) antioxidants milk mineral (MM), phytate, and sodium tri-polyphosphate (STPP) in raw ground chicken patties. In the first study samples of beef semitendinosus muscle, boneless and skinless chicken breast, and yellowfin tuna loins were chosen and packaged with four different pad types. Red meats and chicken exhibited trends as would normally be expected during storage. Specifically, color became less appealing (beef and tuna color changed from red to brown, and chicken changed from yellow–pink to grey); pH increased, microbial counts increased, and lipid oxidation (rancidity) increased. Lightness (L*) values for chicken were within 46 – 54, for tuna L* value range was 21-26. Redness/greenness (a*) is an indicator of freshness in red meats, and for beef steaks an average value of 12.32 was noted on day 8, indicative of fresh red color. Recorded average lipid oxidation (TBA values in mg/kg of meat) for chicken (< 0.19 mg/kg) and tuna were low (< 0.16 mg/kg) and for beef (1.06 mg/kg). Even though there was a significant effect of storage time (P < 0.05) as expected, no significant (P >0.05) differences were observed between the four tested pad types over the 8-day testing period. In study 2, (Chapter 4) a significant antioxidant effect (P < 0.05) was observed in L* values of ground chicken color between treatments. Milk mineral effectively preserved fresh color and slowed lipid oxidation in chicken patties by day 10. Inverse correlations (P < 0.001) were observed between pH (increasing), and lightness, redness values (decreasing) from day 1 through 10. Increased pH levels from slightly acidic to basic or physiological pH resulted in high numbers for total aerobic plate-counts. There was a significant antioxidant effect on lipid oxidation values by day 10; eugenol and MM were more effective (P < 0.05) than STPP in controlling lipid oxidation measured as thiobarbituric acid reactive substances (0.198 mg/kg, 0.198 mg/kg, and 0.268 mg/kg, respectively). In conclusion, CO2 generating absorbent pads did not have a positive effect on meat quality, while the antioxidant milk mineral efficiently maintained color, and pH, and controlled lipid oxidation and limited the growth of aerobic bacteria when compared to other antioxidants.
242

Produção e qualidade de batata sob influência de fertilização, massa de tubérculos sementes e regimes hídricos /

Viana, Jonathan dos Santos January 2019 (has links)
Orientador: Rogério Teixeira de Faria / Resumo: Os efeitos do manejo da irrigação, dos tubérculos sementes e fertilização na produção e qualidade da batata são discutidos como relevantes para o desenvolvimento do crescimento da cultura. A cultura da batata apresenta ótimas respostas a irrigação localizada, porém para que se obtenha sucesso se fazem necessários mais estudos. Dada a importância que essa cultura tem na mesa dos consumidores objetivou-se com essa pesquisa avaliar a produção e qualidade de batata sob influência de fertilização, massa de tubérculos sementes e regimes hídricos. O estudo foi realizado com batata cultivar Orchestra, em delineamento experimental de blocos aos acaso com seis repetições com parcelas subdivididas em fertilizações na parcela e massa de tubérculos sementes na subparcela, no qual incluiu 3 níveis de formas de fertilização: F1 – adubação convencional, F2 – fertirrigação de acordo com a marcha de absorção da cultura, F3 – fertirrigação parcelada em três vezes; 2 níveis de massas de tubérculos sementes: TS1 < 50g e TS2 > 50g. Maior produtividade (48,18 Mg ha-1) e batata graúda (43,67 Mg ha-1) foram obtidas no tratamento fertirrigação (marcha de absorção) e massas de tubérculos sementes > 50 g (48,61 Mg ha-1 e 42,78 Mg ha-1) no regime hídrico (RH) 100%ETc. Porém para as plantas submetidas ao RH 50%ETc para a variável produtividade de tubérculos não foi verificado diferença (P>0,05) nos fatores fertilização e massa de tubérculos sementes. Maior eficiência do uso da água é atribuída ao RH 50%ET... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The results of nutrient analysis and fertilization in potato production and quality are discussed as relevant to the development of crop growth. The potato crop presents excellent responses to localized irrigation, but to be successful. Given the opportunity that culture in the table of customers was aimed at that survey the production and quality of potato under influence of fertilization, mass of tubers, seeds and water regimes. The study was conducted with potato to crop Orchestra. The experimental design was a randomized block design with six replications in subdivided plots with fertilizations in the plot and mass of seed tubers in the subplot, which included 3 levels of fertilization: F1 - conventional fertilization, F2 - fertigation according to uptake of the crop, F3 - fertigation in three times; 2 levels of tuber seed masses: TS1 <50g and TS2> 50g. Higher productivity (48.18 Mg ha-1) and large potato (43.67 Mg ha-1) were obtained in the fertigation treatment and mass of tubers seeds> 50 g (48.61 Mg ha-1 and 42.78 Mg ha-1) in the water regime (RH) 100% ETc. However, for the plants submitted to RH 50% ETc for the variable yield of tubers, no difference (P> 0.05) was observed in the factors of fertilization and mass of seed tubers. Greater efficiency of water use is attributed to RH 50% ETc for tubers seeds greater than 50 g of 39.82 kg m-3 of water. The highest coverage ratio is attributed to tubers under 100% ETc regime with 89 days of cycle length. There was variatio... (Complete abstract click electronic access below) / Mestre
243

Temporal and Spatial Patterns in Optical Properties of Colored Dissolved Organic Matter on Florida’s Gulf Coast: Shelf to Stream to Aquifer

Conmy, Robyn Nicole 31 March 2008 (has links)
Characterization of Colored Dissolved Organic Matter (CDOM) in surface and ground waters in South Florida was conducted using fluorescence and absorption spectroscopy. Waters of the West Florida Shelf are heavily influenced by many river systems on Florida's Gulf Coast that, to the first order control CDOM distributions on the shelf. Seasonal surveys revealed that changes in the underwater light field as a result of major hurricanes and resuspension events are linked closely with a number of factors prior to a storm's passing such as the presence of persistant blooms, rainfall and discharge. Additionally, storm track and wind direction were found to play a significant role in CDOM signatures. A study of ten riversheds located between the Mississippi / Atchafalya River system and the Shark River in the Everglades revealed a wide range in CDOM seasonality. A regional dependence of CDOM was also found, where highest aromaticity and concentration of organic material was found for the southernmost watersheds. Basin characteristics, vegetation differences, land use and climatic patterns are implicated in the cause for regional differences. In addition to surface flow, organic material in groundwater was measured in deep and shallow aquifers surrounding the Tampa Bay Estuary. As a result of strong hydrologic links between shallow aquifers and the overlying surface waters, CDOM in both reservoirs were found to be quite similar. Deep aquifers (> 150 ft) however are less concentrated and have CDOM signatures more similar to marine waters. This suggests similar biogeochemical pathways of the material, including the influence of the aquatic microbial community. Furthermore, multi-spectral CDOM fluorescence measurements were shown to be a potential indicator of groundwater presence in Tampa Bay during times of low surficial discharge to the bay, and when some rivers are almost entirely spring-fed. Investigating CDOM distribution and signatures is vital to carbon budget and cycling questions. The amount and quality of organic material has significant implications for ecosystems, thereby affecting organisms that use CDOM as a food source, light availability for photosynthesis, UV shading provided to biota, satellite estimates of chlorophyll a, metal binding, materials transport and overall water quality.
244

Low frequency variations in the sea level and currents over the Oregon continental shelf

Cutchin, David L. 14 July 1971 (has links)
Sea level and current observations made over the Oregon continental shelf exhibit wavelike characteristics in a frequency band from approximately 0.15 to 0.45 cpd. In a narrow band around 0.22 cpd the current-sea level relationship is consistent with the predicted values for the first mode of Robinson's continental shelf waves. In addition, an interesting relationship exists between the form of the sea level-current coherency spectra and the arrangement of the maximum frequencies for the first three shelf wave modes. The currents were measured in 100 m of water about seven nautical miles off Depoe Bay, Oregon. Current meters were placed at 25, 50 and 75 m depth. The duration of the experiment was from 18 April 1968 until 11 September 1968. Due to some instrument failures a complete current data set for this period was not obtained. Simultaneous and continuous measurements of surface elevation and atmospheric pressure were also obtained at Newport, Oregon, a nearby coastal station. Shelf wave dispersion curves and eigenfunctions for the Oregon coastal profile are computed using a new numerical technique. These are compared with a low frequency (about 0.03 cpd to 0.75 cpd) spectral analysis of the current, sea level and atmospheric pressure records. The relative vertical uniformity of the currents, as a function of frequency, is examined. The longshore component of the current appears to be substantially more barotropic than the onshore-offshore component. / Graduation date: 1972
245

Consumers' attitudes regarding the link between frozen and fresh vegetables and health / Emdri Maria van der Walt

Van der Walt, Emdri Maria January 2003 (has links)
Thesis (M.Sc. (Dietetics))--North-West University, Potchefstroom Campus, 2004.
246

DEM generation and ocean tide modeling over Sulzberger Ice Shelf, West Antarctica, using synthetic aperture radar interferometry

Baek, Sang-Ho, January 2006 (has links)
Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 132-144).
247

Etude numérique et mathématique des transitions abruptes "fort frottement - faible frottement" : application aux transitions "calottes polaires - ice shelf"

Lestringant, Renaud 23 February 1994 (has links) (PDF)
La jonction "calotte -ice shelf" est le siège du transfert de masses glaciaires entre la calotte et l'ice shelf. Cette définition est déjà en soi une modélisation partielle de la masse de glace. On peut en effet considérer qu'elle est une combinaison de trois types de sous-systèmes: la calotte, l'ice stream, et l'ice shelf. Il est possible de discriminer chacun d'eux par le type de contrainte qui domine l'écoulement. La calotte constitue la plus grande partie en volume de la masse de glace et sa caractéristique essentielle -du moins en ce qui concerne sa dynamique réside dans le fait qu'elle repose sur un socle rocheux. L'ice shelf quant à lui repose entièrement sur l'océan: il flotte. La troisième composante, l'ice stream, peut être considérée comme un cas intermédiaire entre les deux autres. On est donc amené à distinguer deux types de régimes d'écoulement: - dans la calotte, un écoulement par cisaillement dû à l'interaction glace-socle rocheux. - dans l'ice shelf, un écoulement dominé par les contraintes déviatoriques longitudinales; on obtient alors un écoulement par extension.
248

Effect Of High Hydrostatic Pressure Treatment On Some Quality Properties, Squeezing Pressure Effect And Shelf Life Of Pomegranate (punica Granatum) Juice Against Thermal Treatment

Gultekin, Necmiye Busra 01 September 2012 (has links) (PDF)
The aim of this study was to investigate the effect of high hydrostatic pressure (HHP) treatment (200, 300, 400 MPa / 5
249

Benthic Function and Structure in the Northern Gulf of Mexico Hypoxic Zone: Sediment Biogeochemistry and Macrobenthic Community Dynamics in the Dead Zone

Nunnally, Clifton 2012 May 1900 (has links)
Coastal low oxygen areas are expanding globally and are predicted to increase in size and duration due to climatic changes associated with a warming ocean. The Gulf of Mexico Hypoxic Zone (GoMHZ) is the second largest regularly occurring hypoxic habitat in the world and has increased in size since it was first mapped in the 1980s. The Mississippi Atchafalaya River System (MARS) floods the Louisiana continental shelf with fresh water high in nitrogenous compounds enhancing primary production which sinks to the sea floor. Stratification that occurs as a result of density differences and coastal currents creates a strong pycnocline that prevents bottom waters from being aerated causing seasonally hypoxic bottom waters (< 2.0 mg L^-1). The Mechanisms Controlling Hypoxia (MCH) project (hypoxia.tamu.edu) made regular cruises during 2004-2005 and 2007-2009 to the GoMHZ performing shelf wide hydrographic surveys and occupying central mooring sites within theoretical zones of differing hypoxic potential. Sediment cores were collected for incubation experiments using Batch Microincubation Chambers (BMICs) to measure rates of sediment community oxygen consumption and nutrient regeneration. Results of incubation experiments characterized sediments as net sources of dissolved inorganic nitrogen, mostly ammonium, and silicate and a net sink of phosphate. Modeling simulations of benthic-pelagic coupling focused in the western study zones related field measurements of benthic nutrient regeneration and primary production to important processes that maintain summertime hypoxia when surface waters are nitrogen limited. After incubations were completed macrofaunal individuals were removed from the cores enumerated and identified to the lowest possible taxon. Macrofauna communities in 2004-2005 were dominated by a hypoxia tolerant community dominated by polychaetes. Hurricanes Katrina and Rita in August and September of 2005 drastically reorganized macrobenthic communities decreasing abundances and negatively impacting diversity. These new communities collapsed under hypoxic stresses potentially impacting the ability of demersal foragers to utilize an important food resource. Large variations in biogeochemical fluxes and patchy distribution of fauna impeded the delineation of significant zones in benthic function and structure.
250

Deep structure and sub-basalt exploration of the mid-Norwegian margin with emphasis on the Møre margin

Reynisson, Reynir Fjalar January 2010 (has links)
This thesis addresses the use of potential field data in two main topics: sub-basalt exploration and structure of the deeper crust. Synthetic models and forward models of the Møre margin were constructed to test the sensitivity of the various potential field methods. The synthetic models demonstrate that forward modelling of the gravity and magnetic data is a valuable tool in basement recognition in sub-basaltic settings and the use of gravity gradients further limits the modelling ambiguity and improves the basement mapping. Deep sills, as observed in the Møre Basin, cannot be identified from the gravity and magnetic data alone but the lava flows have a clear effect on the gravity and magnetic signature if thicker than ~1 km. Experiments with Euler Deconvolution reveal the limitations of the method in sub-basaltic settings. A 3D regional gravity and magnetic model of the Møre margin integrated with seismic and well data gives a novel view on the architecture of the continental crust, the distribution of high density lower crust, and the Moho topography. The isostatic response of the water and sediment loading reflected by the Moho provides further insight in the evolution of the margin. The results from the Møre margin model merged with results from a 3D model of the Vøring and Lofoten margins give a regional view on the deep structures on the mid-Norwegian margin. Combination of the modelling results and isostatic considerations provide means to address the origin of the lower crustal body on the margin and the evolution of the whole mid-Norwegian margin.

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