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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.
151

Characterization of Lactose Monolaurate for its Antimicrobial and Emulsification Properties and its Effect on Crystallization Behavior of Anhydrous Milk Fat

Wagh, Ashwini 01 May 2013 (has links)
There is a constant need of new synthetic emulsifiers in the food industry. Sugar esters are widely used as food grade synthetic emulsifiers, amongst which sucrose esters are the most common. Although sucrose esters are used very frequently, little is known about the use of lactose esters in food. There is a need for characterization of lactose esters before they can be used in foods. The objective of this study was to characterize a lactose ester, lactose monolaurate (LML) as an antimicrobial agent on food pathogens, evaluate its effect on 20 % oil-in-water emulsions as an emulsifier, and to explore its effect on crystallization behavior of anhydrous milk fat. In the first study (Chapter 3), the effect of LML was evaluated on survival of some Gram-positive and Gram-negative bacteria. For Listeria monocytogenes, a concentration of 1 mg/ml showed some inhibition in growth media whereas the cells were completely killed at 5 mg/ml. For Mycobacteria, an LML concentration between 0.1-1mg/ml was lethal. Scanning electron microscopy was also conducted to examine any changes in the morphology of cells. Listeria exhibited a change in morphology and a wrinkling effect was shown in Mycobacteria. In the second study (Chapter 4), the effect of LML as an emulsifier was evaluated in 20 % oil-in-water emulsions. The use level of LML was comparable to commercially available emulsifier polysorbate 20, and produced comparable stabilization in the emulsions upon use. In this study, an attempt was also made to optimize the synthesis of LML with respect to the immobilized enzyme and solvent combination. It was concluded that for 20 % oil-in-water emulsions, LML is a promising emulsifier at 0.5%. In the third study (Chapter 5), the effect of LML was evaluated at two concentrations on the crystallization behavior of anhydrous milk fat at two temperatures with high and low supercooling. On application of high intensity ultrasound (HIU) to anhydrous milk fat (AMF) at 31°C and 0.05 % LML the effect on viscosity of sample and crystallization behavior was evaluated. It was concluded that the viscosity of AMF decreased with the addition of 0.05% LML. The lower viscosity of anhydrous milk fat on addition of LML could be restored with the application of HIU.
152

Kohlenhydratmalassimilation bei der Hashimotothyreoiditis / Evidence of impaired carbohydrate assimilation in euthyroid patients with Hashimoto's thyroiditis

Heckl, Steffen January 2014 (has links) (PDF)
Die autoimmune Thyreoiditis nach Hashimoto stellt aktuell eine der häufigsten Autoimmunerkrankungen eines Organs und die häufigste Ursache der Hypothyreose dar. Die Hashimotothyreoiditis (HT) weist eine hohe Prävalenz und Inzidenz auf. Es existieren Hinweise, dass die Inzidenz der HT aus noch nicht geklärten Gründen gestiegen sein könnte. Die Kohlenhydrate Fruktose, Laktose und Sorbitol werden in der Lebensmittelproduktion umfassend eingesetzt. Insbesondere die industrielle Verwendung sowie der weltweite Konsum von Fruktose und Laktose unterlagen in den letzten Jahrzehnten einer rasanten Steigerung, obwohl ein hoher Prozentsatz der Bevölkerung zur Malassimilation jener Kohlenhydrate prädisponiert ist. In einer internistischen Praxis (Praxis Frau Dr. med. I. Heckl, Bad Homburg) zeigte sich, dass HT-Patienten trotz verifizierter Euthyreose vermehrt über gastrointestinale Symptome berichteten. Unter anderem wurden eine bakterielle Fehlbesiedelung des Dünndarmes und eine Zöliakie ausgeschlossen. In der weiteren Abklärung durch die Praxis Dr. I. Heckl wurde eine deutliche Häufung der Malassimilation der Kohlenhydrate Fruktose, Laktose oder Sorbitol unter euthyreoten HT-Patienten ersichtlich. In Abhängigkeit von einer konsequenten Nahrungsumstellung normalisierten sich regelmäßig das Befinden der Patienten sowie die sonographischen, die serologischen und die laborchemischen Marker der HT, sodass man einen ursächlichen Zusammenhang empirisch vermuten konnte. Im Rahmen einer prospektiven Studie sollte dieser neu beobachtete Zusammenhang zwischen der HT und der Kohlenhydratmalassimilation in der Klinik und Poliklinik für Nuklearmedizin der Universität Würzburg untersucht werden. In einem unizentrischen Fall-Kontroll-Studiendesign wurden 45 euthyreote HT-Patienten und 38 schilddrüsengesunde Kontrollpersonen auf das Vorliegen einer Kohlenhydratmalassimilation mittels des Wasserstoffatemtests (H2-Atemtest) untersucht. Alle Probanden erhielten einen Fruktose-H2-Atemtest sowie einen Laktose-H2-Atemtest inklusive einer kapillären Blutglukosemessung. Im Falle eines positiven Ergebnisses des Fruktose-H2-Atemtests wurde ein Glukose-H2-Atemtest zum Ausschluss einer bakteriellen Fehlbesiedelung des Dünndarmes durchgeführt. Lieferte der Fruktose-H2-Atemtest ein negatives Ergebnis, so folgte ein H2-Atemtest mit Sorbitol. Das Auftreten gastrointestinaler Symptome während der Testdurchführung wurde dokumentiert. Symptomfragebögen und semiquantitative Ernährungsfragebögen im retrospektiven Design dienten der Erfassung alltäglicher Symptome und Ernährungsgewohnheiten. Blutproben dienten der Messung von Schilddrüsenhormonen, Schilddrüsenautoantikörpern, Gewebstransglutaminase-Antikörpern und Antiparietalzell-Autoantikörpern. Unter den euthyreoten HT-Patienten konnte ein signifikant häufigeres Auftreten der Fruktose- sowie der Laktosemalassimilation im Vergleich zu den schilddrüsengesunden Kontrollpersonen demonstriert werden. Die Fruktosemalassimilation wurde bei den HT-Patienten mit 48,9% signifikant häufiger als in der Kontrollgruppe nachgewiesen (p=0,035). Im Kontrollgruppenkollektiv hatte eine Fruktosemalassimilation lediglich bei 26,3% der Probanden bestanden. Eine Laktosemalassimilation wurde bei den HT-Patienten mit 42,2% signifikant häufiger als im Kontrollkollektiv diagnostiziert, welches in 21,1% der Fälle eine Laktosemalassimilation aufwies (p=0,04). Insgesamt lag eine Fruktose- und / oder Laktosemalassimilation bei 73,3% der HT-Patienten und bei 42,1% der Kontrollgruppenprobanden vor. Somit vertrugen nur 26,7% der Fallgruppe, jedoch 57,9% der Kontrollgruppe beide Kohlenhydrate (p=0,004). Hinsichtlich der Prävalenz der Sorbitolmalassimilation oder eines positiven Glukose-H2-Atemtestes kam kein signifikanter Unterschied zur Darstellung. Die Auswertung der Ernährungsfragebögen zeigte für beide Kollektive eine vergleichbare durchschnittliche Konsummenge der jeweiligen Kohlenhydrate auf. Gastrointestinale Symptome waren während des Laktose-H2-Atemtests sowie während des Fruktose-H2-Atemtests jeweils in der Fallgruppe signifikant häufiger anzutreffen als in der Kontrollgruppe. Auch im Hinblick auf das Alltagsleben beschrieben die euthyreoten HT-Patienten signifikant häufiger unter den folgenden Symptomen zu leiden: Weicher Stuhlgang, Oberbauchschmerzen, Meteorismus, laute Darmgeräusche, „Kugelbauch“, Sodbrennen, Schleimauflagerungen des Stuhlgangs, Obstipation, Müdigkeit, postprandiale Kraftlosigkeit, Depressionen, Heißhunger auf Süßes, Migräne, Konzentrationsmangel und eine vermehrte Infektanfälligkeit. Zur Kausalität des hier erstmals beschriebenen Zusammenhangs existieren mehrere Hypothesen. Die Einteilung der HT-Patienten gemäß ihrer Schilddrüsenautoantikörper-Titer in Subkollektive ergab keinen Hinweis auf einen Einfluss der Aktivität des Autoimmungeschehens auf die Häufigkeit der Kohlenhydratmalassimilation. Es steht zur Diskussion, ob die HT zur Entstehung einer Kohlenhydratmalassimilation führen, oder ob eine vorbestehende Kohlenhydratmalassimilation, im Sinne eines neu identifizierten Risikofaktors, zur Genese einer HT prädisponieren könnte. In der vorliegenden Studie konnte erstmalig eine signifikante Häufung der Kohlenhydratmalassimilation bei euthyreoten HT-Patienten aufgezeigt werden. Vor dem Hintergrund der weitreichenden lebensmittelindustriellen Verwendung und des hohen Konsums der Kohlenhydrate Fruktose, Laktose und Sorbitol sowie der hohen Prävalenz und Inzidenz der HT, ergibt sich eine hohe Relevanz des hier nachgewiesenen Zusammenhangs. In der differenzialdiagnostischen Abklärung gastrointestinaler Beschwerden bei euthyreoten HT-Patienten nimmt die hier beschriebene Assoziation zwischen der HT und der Kohlenhydratmalassimilation einen besonderen Stellenwert ein. Die Kohlenhydratmalassimilation verkörpert einen neuen, sowohl klinisch, als auch potentiell pathogenetisch relevanten Aspekt der Hashimotothyreoiditis. / Background/Objectives: Hashimoto’s thyroiditis (HT) represents a wide-spread autoimmune disease. In euthyroid patients with HT, an impaired assimilation of common carbohydrates has been observed. Our objectives were to compare the frequency of (1) fructose (FM), lactose (LM) and sorbitol malassimilation (SM), (2) gastrointestinal symptoms (GS) following carbohydrate ingestion and (3) recurrent GS relevant to the participants’ daily lives. Subjects/Methods: We conducted a prospective case–control study of 45 ambulatory patients with HT and 38 healthy volunteers, matched with regard to age, gender and area of origin. Hydrogen breath tests with fructose, lactose, sorbitol and glucose were performed, the lactose testing additionally comprising measurements of capillary blood glucose (cBG). GS during the tests and recurrent GS concerning the participants’ daily lives were assessed. A food-frequency questionnaire was administered. Results: FM was diagnosed in 48.9% of patients compared with 26.3% of the control group (P=0.035). In all, 42.2% of patients with HT and 21.1% of healthy controls showed LM (P=0.04). FM and/or LM was present in 73.3% of the patients and in 42.1% of healthy controls (P=0.004). GS after the ingestion of fructose (P=0.003) or lactose (P=0.025) and recurrent GS were significantly more prevalent in the case group. The consumption of free fructose, lactose or sorbitol did not differ. Conclusions: Carbohydrate malassimilation and gastrointestinal complaints are frequent in euthyroid patients with HT, leading to novel clinical and pathophysiological considerations and concepts.
153

Isolation and characterization of components from whey

Xu, Yue, University of Western Sydney, Hawkesbury, Faculty of Science, Technology and Agriculture, School of Food Science January 1996 (has links)
The structure, functionality, isolation methods and applications of whey components, particularly the proteins and lactose, have been extensively studied. These studies have had a great impact on the food industry where whey components are increasingly being used as food ingredients. Two generations of whey protein product, namely Lactalbumin, produced by heat-induced precipitation, and Whey Protein Concentration/ Isloate, produced by ultrafiltration/ ion exchange chromatography, have been commercialised. Crystalline lactose in the food and pharmaceutical grades is also being produced. Recently, research activities in whey fractionation have shifted to the isolation of the minor components. This thesis is aimed at developing a Total Whey Utilization strategy by which the several components of the whey stream would be completely recovered by fractionation, resulting in little or no residue to be disposed of in the wastewater stream. Therefore, this study was initially dedicated to the development of novel separation methods which would be suitable for the Total Whey Utilization process. The development of those techniques revealed some previously unknown feature of whey components. The mechanisms of the separation methods have been also investigated. Although crystallization is an efficient method for fractionation or purification, its disadvantage is that the mother liquor is a wastewater containing high salt and BOD (Biological Oxygen Demand). The chromatographic method has been investigated in this work to separate the mother liquor or permeate into lactose and mineral fractions such that a goal of this thesis, namely a 'clean' water stream after processing whey, can be finally achieved. These studies have focused on the effect of resin type, salt form of the resin and the operating conditions on the separation of the lactose and mineral fraction. / Doctor of Philosophy (PhD)
154

Bioconversion and separation of milk carbohydrates on nanomembranes

Pikus, Wojciech 06 1900 (has links)
Cost-effective processing of dairy whey permeates is important to the environment and economics of the agriculture industry in Canada. Bioconversion of whey permeates is an attractive means of obtaining value-added adjuncts with improved nutritional and functional properties. In the past, cost-effective technologies to recover additional value from whey permeates at a low cost were lacking. Currently, such a technological platform is now feasible with the introduction of new modern bioconversion technologies that incorporate batch or continuous bioreactors, and use ultra- and nano-filtration membranes for the separation of whey permeate components. In this dissertation, a novel processing methodology is described. This methodology, which is a desirable configuration for food manufacturers includes a stirred batch nanomembrane bioreactor equipped with a crossflow nanomembrane and offers lactose bioconversion with an immobilized biocatalyst, product separation, and biocatalyst recovery in a batch operation. The major focus of this research was on: a) the development of a new analytical methodology for carbohydrate measurement during the lactose bioconversion process, b) the selection, testing and integration of highly selective nanomembranes to separate the desired substrates, whey permeate carbohydrates, from the reaction mixture, and c) the production of a stable and highly active and specific immobilized biocatalyst. Noticeably, this methodology was designed, developed and tested for the bioconversion of lactose, but could also be used for the bioconversion of other carbohydrate feedstocks. The food industry in Canada needs an integrated approach to achieve complete lactose reclamation and use. This research project offers such a solution. The research described in this dissertation presents an integrated model of a stirred batch bioreactor that may support not only current, but also future research, and may economically impact the development and bioconversion of whey permeates containing lactose. This may lead to the development of a continuous processing methodology for low cost recovery of lactose from whey permeates and simultaneous conversion to value-added products. / Bioresource and Food Engineering
155

Characterization of Lactose Monolaurate for its Antimicrobial and Emulsification Properties and its Effect on Crystallization Behavior of Anhydrous Milk Fat

Wagh, Ashwini 01 May 2013 (has links)
There is a constant need of new synthetic emulsifiers in the food industry. Sugar esters are widely used as food grade synthetic emulsifiers, amongst which sucrose esters are the most common. Although sucrose esters are used very frequently, little is known about the use of lactose esters in food. There is a need for characterization of lactose esters before they can be used in foods. The objective of this study was to characterize a lactose ester, lactose monolaurate (LML) as an antimicrobial agent on food pathogens, evaluate its effect on 20 % oil-in-water emulsions as an emulsifier, and to explore its effect on crystallization behavior of anhydrous milk fat. In the first study (Chapter 3), the effect of LML was evaluated on survival of some Gram-positive and Gram-negative bacteria. For Listeria monocytogenes, a concentration of 1 mg/ml showed some inhibition in growth media whereas the cells were completely killed at 5 mg/ml. For Mycobacteria, an LML concentration between 0.1-1mg/ml was lethal. Scanning electron microscopy was also conducted to examine any changes in the morphology of cells. Listeria exhibited a change in morphology and a wrinkling effect was shown in Mycobacteria. In the second study (Chapter 4), the effect of LML as an emulsifier was evaluated in 20 % oil-in-water emulsions. The use level of LML was comparable to commercially available emulsifier polysorbate 20, and produced comparable stabilization in the emulsions upon use. In this study, an attempt was also made to optimize the synthesis of LML with respect to the immobilized enzyme and solvent combination. It was concluded that for 20 % oil-in-water emulsions, LML is a promising emulsifier at 0.5%. In the third study (Chapter 5), the effect of LML was evaluated at two concentrations on the crystallization behavior of anhydrous milk fat at two temperatures with high and low supercooling. On application of high intensity ultrasound (HIU) to anhydrous milk fat (AMF) at 31°C and 0.05 % LML the effect on viscosity of sample and crystallization behavior was evaluated. It was concluded that the viscosity of AMF decreased with the addition of 0.05% LML. The lower viscosity of anhydrous milk fat on addition of LML could be restored with the application of HIU.
156

Synthesis of oligo(lactose)-based thiols and their self-assembly onto gold surfaces

Fyrner, Timmy, Ederth, Thomas, Aili, Daniel, Liedberg, Bo, Konradsson, Peter January 2013 (has links)
The ability to produce monomolecular coatings with well-defined structural and functional properties is of key importance in biosensing, drug delivery, and many recently developed applications of nanotechnology. Organic chemistry has proven to be a powerful tool to achieve this in many research areas. Herein, we present the synthesis of three oligo(lactosides) glycosylated in a (1 → 3) manner, and which are further functionalized with amide-linked short alkanethiol spacers. The oligosaccharides (di-, tetra-, and hexasaccharide) originate from the inexpensive and readily available lactose disaccharide. These thiolated derivatives were immobilized onto gold surfaces, and the thus formed self-assembled monolayers (SAMs) on planar gold were characterized by wettability, ellipsometry and infrared reflection–absorption spectroscopy. Further, the ability of these SAMs to stabilize gold nanoparticles in saline solutions was also demonstrated, indicating that the oligosaccharides may be used as stabilizing agents in gold nanoparticle-based assays.
157

Optimization and validation of the method lactose intolerance genotyping with real-time PCR

Stenberg, Jenny January 2011 (has links)
Abstract Primary lactose intolerance has been associated with a single nucleotide polymorphism located upstream of the lactase gene. The most common diagnostic tests for lactose intolerance are time-consuming and the patient is not allowed to eat and drink for 12 hours before the test is carried out. A method that can establish the genotype would be an easier way of diagnosing lactose intolerance compared to fenotypic lactose intolerance tests. Optimization and validation of a previously published method was performed with real-time polymerase chain reaction. We used whole blood from de-identified blood donors. During the optimization and validation we used a positive control, genotype C/T from Laboratoriemedicin Västernorrland, Sundsvall. The whole-blood was extracted using the MagNa Pure LC instrument. The reagent used was KAPA PROBE FAST qPCR Master Mix. The optimized program for real-time PCR was established to be 95°C 3min [95°C x 3sec, 55°C x 20sec, detection, 72°C x 15sec] x 50 cycles. Optimal probe concentration was found to be 0.2µM and primer concentration will be 0.5µM. This genotyping method is a good first-stage screening test for lactoseintolerance. Before it can be used as a routine method further validation will be necessary in order to ensure that the evaluation of the results can be done in an easy and secure way.
158

Evaluation of agricultural disinfectants and necrotic enteritis preventatives in broiler chickens

Stringfellow, Kendre Duaron 15 May 2009 (has links)
The objective of this study was to determine the effect of time, temperature and organic matter on disinfectant efficacy. Staphylococcus aureus (SA) and Salmonella Typhimurium (ST) were used as organisms to represent Gram positive and Gram negative bacteria, respectively, commonly found in poultry housing. Three independent experiments evaluated the effect of temperature, time, and organic matter on the efficacy of working concentrations of disinfectants against representative organisms found in commercial poultry housing. Quaternary ammonium, chlorhexidine, phenolic and binary ammonium based solutions represented disinfectants commonly used within the poultry industry. Results from these experiments indicated that long term storage of disinfectants will reduce their efficacy against SA. However, a reduction (p ≤ 0.05) in efficacy was observed with the phenolic compound against ST at elevated temperatures. Following the inclusion of organic matter (OM), reduced (p ≤ 0.05) efficacy of all disinfectants was observed in a dose dependent manner against both organisms, with the exception of the phenolic compound against SA. Fresh disinfectant performed better (p ≤ 0.05) in the presence of OM than 30 wk old disinfectant. These results emphasize the need to use fresh disinfectants and that OM should be removed prior to disinfection. We also evaluated the effect of bismuth citrate, lactose and citric acids on the development of necrotic enteritis in broilers. Clostridium perfringens’ associated necrotic enteritis in poultry causes significant loss and increased morbidity in the industry. Due to the reduced usage of antibiotic growth promoters, the incidence of necrotic enteritis has increased. These experiments evaluated different levels of bismuth citrate and bismuth citrate with lactose or citric acid added, on lesion development, bacterial intestinal colonization of C. perfringens and pH levels in the gut of broilers orally challenged with C.perfringens. Results from this investigation indicate that bismuth citrate at 100 ppm and 200 ppm caused a reduction (p ≤ 0.05) in C. perfringens colonization and intestinal lesion development. The addition of dietary lactose to bismuth citrate enhanced the effect of bismuth citrate on intestinal lesion development. These data suggest that bismuth citrate alone or in combination with dietary lactose will reduce intestinal lesion development in broilers with necrotic enteritis.
159

Lactose-utilization and gluconic acid production by genetically modified strains of Gluconobacter oxydans /

El-Sayed, Mohamed Mostafa Hesham. January 2000 (has links)
Thesis (doctoral)--Universität Kiel, 2000.
160

Influence of carrier particle size and surface roughness on the aerosol performance of DPI formulations

Donovan, Martin Joseph 16 March 2015 (has links)
The influence of the size and morphology of carrier particles on drug dispersion performance from passive dry powder inhalers has been extensively studied topic, and a consensus has been reached regarding the adverse effect that larger carrier particle diameters impart to aerosol performance. However, previous studies have generally employed only a few carrier particle size fractions, generally possessing similar surface characteristics. Accordingly, theories developed to explain the influence of the physical characteristics of carrier particles on performance relied heavily on both extrapolation and interpolation. To fill in the gaps from the literature and simultaneously evaluate the influence of carrier particle size and morphology, a comprehensive study was undertaken using 4 lactose grades, each sieved into 13 contiguous sizes, to prepare 52 formulations incorporating a unique lactose grade-size population. The aerosol performance results indicated that large carrier particles possessing extensive surface roughness can improve drug dispersion, in contrast to what has been previously reported. It is proposed that this may be attributed to mechanical detachment forces arising from collisions between the carrier particle and inhaler during actuation. Based on these observations, a novel dry powder inhaler platform was developed, employing carrier particles much larger (> 1 mm) than previously explored in both the scientific and patent literature. Optimization of this technology required the judicious selection of a carrier material, and following an extensive screening process, low-density polystyrene was selected as a model candidate. Given its low mass, diameters in excess of 5-mm could be employed as carriers while still generating high detachment forces. To minimize drug particle aggregation, a novel drug-coating method employing piezo-assisted particle dispersion was developed to compensate for the reduced surface area of the novel carrier particles. In addition, the selection of a suitable inhalation device prototype was instrumental to the overall performance of the technology. In vitro testing of the novel large carrier particles yielded emitted fractions in excess of 85%, and overall drug delivery of up to 69% of the nominal dose. / text

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