• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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.
1

Control of <em>Listeria monocytogenes</em> in Ready-to-Eat Meat Containing Levulinate, Lactate, or Lactate and Diacetate

Thompson, Rebecca L. 01 May 2007 (has links)
Control of the pathogen Listeria monocytogenes in ready-to-eat (RTE) meats is a major concern in the food industry. The objective of this study was to compare the growth of L. monocytogenes on refrigerated RTE meats containing sodium levulinate (4-oxopentanoic acid, a five carbon organic acid with GRAS status), sodium lactate, or a combination of sodium lactate and sodium diacetate. Turkey roll and bologna were prepared to contain (wt/wt) sodium lactate (2%); sodium lactate in combination with sodium diacetate (1.875% sodium lactate, 0.125% sodium diacetate); sodium levulinate (1, 2, or 3%); or no antilisterial additive. Samples were sliced, inoculated with a 5-strain cocktail (102 to 103 CFU/cm2) of L. monocytogenes, vacuum packaged, and stored at 2°C for 0-12 weeks. Triplicate packages of each treatment were analyzed bi-weekly for growth of the pathogen. Bacterial counts exceeded 105 CFU/cm2 in controls after 4 weeks in turkey and over 106 CFU/cm2 after 8 weeks in bologna. In turkey, L. monocytogenes showed significant growth in samples containing sodium lactate after 6 weeks(>104 CFU/cm2) and after 8 weeks when used in combination with diacetate. Further, samples containing 1% sodium Jevulinate did not show significant growth of the pathogen for 10 weeks (~104 CFU/cm2), while those containing 2% and 3% levulinate inhibited growth for 12 weeks. In bologna, adding any antimicrobial inhibited growth for 12 weeks. Finally, Listeria-free samples of turkey roll and bologna, containing the various organic acid salts, were evaluated by members of consumer taste panels. Statistical analysis (ANOV A) showed that there were no differences in overall liking of samples of turkey roll (p = 0.19) or bologna (p = 0.42). In turkey, sodium levulinate was more effective at preventing growth of L. monocytogenes, while in bologna it was as effective as the current industry standards lactate and diacetate. Addition of levulinate did not alter the sensory acceptability of either product
2

The degree of phosphorus saturation of agricultural soils in Brazil and Germany: New approaches for risk assessment of diffuse phosphorus losses and soil phosphorus management

Fischer, Peter 30 November 2018 (has links)
Diffuse Phosphor (P)-Austräge aus der Landwirtschaft tragen zur Gewässereutrophierung bei. Der Phosphorsättigungsgrad (DPS) ist ein etablierter Parameter, um das P-Austragsrisiko aus Böden zu erfassen. Ein bodentypunabhängiger Ansatz, der die Abschätzung des DPS durch eine einfache Standardmethode wasserlöslichen P (WSP) ermöglicht (WSP-DPS-Ansatz), wurde an europäischen Böden entwickelt. In der Dissertation wurde dieser Ansatz erstmalig: i) an tropischen Böden getestet und ii) dazu verwendet P-Austragsrisiken von Boden-P-Monitoringdaten und von landwirtschaftlichen Institutionen empfohlenen P-Gehalten abzuleiten. Neben dem DPS wurde der Einfluss der in Brasilien gängigen anorganischen Oberflächendüngung auf das Austragsrisiko mittels Laboranalysen und Feldstudien erfasst. Die Bodentypunabhängigkeit des WSP-DPS-Ansatzes wurde für Böden Brasiliens bestätigt. Infrarotspektroskopische Analysen lieferten eine Erklärung für relativ niedrige gelöste P-Konzentrationen im Oberflächenabfluss von Oxisols. Pedotransferfunktionen zwischen WSP und Methoden, die in Brasilien und Deutschland zur Abschätzung pflanzenverfügbaren P verwendet werden, ermöglichten die Berechnung von DPS-Werten aus Monitoringdaten. Erste DPS-Karten zeigten relative geringe Austragsrisiken für das Untersuchungsgebiet in Brasilien und hohe Risiken für Deutschland, die teilweise durch unterschiedliche empfohlene Boden-P-Gehalte erklärbar waren. Um mit einer einfachen und kosteneffizienten Methode sowohl die landwirtschaftliche Produktion als auch den Gewässerschutz zu berücksichtigen, wurden die Wasser- und CaCl2-Methode zur Abschätzung von pflanzenverfügbarem P mit dem WSP-DPS-Ansatz kombiniert. Dieser Ansatz könnte helfen die Herausforderungen zu lösen mit denen die Menschheit in den nächsten Jahrzehnten bezüglich P in der Landwirtschaft konfrontiert sein wird: Einer effizienten Nutzung der limitierten Ressource P und dem Schutz der Gewässer vor diffusen P-Einträgen. / Diffuse phosphorus (P) losses from agriculture contribute to the eutrophication of surface waters. The degree of P saturation (DPS) is an established parameter for assessing the risk of P loss from agricultural soils. A soil type-independent approach for estimating the DPS by a simple standard method of water-soluble phosphorus (WSP; the WSP-DPS approach) was developed on European soils. In the thesis, the WSP-DPS approach was for the first time: i) tested on tropical soils and ii) used to derive P loss risks from soil P monitoring data and from recommended soil P levels by agricultural institutions. In addition to DPS, laboratory analyses and field studies were combined to assess the risk of P loss associated with the superficial application of inorganic fertilizer, which is commonly used in Brazil. The soil type-independency of the WSP-DPS approach was confirmed for soils of Brazil. Infrared spectroscopic analyses provided an explanation for the relatively low dissolved P concentrations in the surface runoff of Oxisols. Pedotransfer functions were determined between WSP and methods used to estimate plant-available P in Brazil and Germany and allowed for the transformation of soil P monitoring data into DPS values. The first DPS maps revealed relatively low P loss risks for the investigation area in Brazil and high risks for Germany. This difference was partly explainable by the recommended soil P levels in the two countries. To consider both agricultural production and the protection of surface waters in soil P management with a simple and cost-effective method, the soil test methods of using water and CaCl2 to estimate plant-available P and the WSP-DPS approach were combined. This approach could help to solve the challenges humanity faces regarding P in agriculture in the coming decades: An efficient use of the limited resource P and the protection of surface waters from diffuse P losses.

Page generated in 0.021 seconds