Dissertations / Theses on the topic 'Lipid oxidation'
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Reid, Vanessa Claire. "Macrophage toxicity of lipid oxidation." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308384.
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Prado-Barragan, Lilia Arely. "Lipid oxidation in a meat fibre system." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294811.
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Walters, Louise. "Lipid oxidation in salt-dried pelagic fish." Thesis, University of Lincoln, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262195.
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Saeed, Suhur. "Lipid oxidation mechanisms and lipid-protein interactions in frozen mackerel (Scomber scombrus)." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/843251/.
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Atlantic mackerel (Scomber scombrus) is a pelagic fish widely distributed along the Northern coast of Great Britain. The lipid content of mackerel was found to be about 13% of the total body weight and 50% of total fatty acids were eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (fatty acids which are reported to reduce the concentration of plasma triglycerides, LDL (low density lipoproteins) and cholesterol in humans and animals). The proximate analysis also showed that mackerel is a good source of protein (20% w/w). The poly unsaturated fatty acids (PUFA) are prone to oxidation during frozen storage leading to rancidity and protein damage. Thus the objective of this project was to prolong the shelf-life of mackerel by controlling and understanding lipid oxidation mechanisms. HPLC, GCMS and 13C NMR spectroscopy were used for the first time to monitor the production of hydroperoxides and their secondary products in fish matched pairs of mackerel fillets were stored at either -20°C or -30°C. In addition fillets were also stored with or without different antioxidants at -20°C. The development of lipid oxidation products were recorded for up to 24 months. The oxidation products identified were mixtures of alcohol derivatives of hydroperoxides, namely: 13-hydroxy-9-trans, 11-cis-octadecadienoic, 13-hydroxy-9-trans, 11-trans-octadecadienoic, 9-hydroxy-10-cis, 12-transoctadecadienoic and 9-hydroxy-10-trans, 12-transoctadecadienoic acids. The amount of hydroxides produced were higher in fillets stored at -20°C compared with fillets stored at -30°C. Similarly, the hydroperoxides produced were considerably higher in samples stored without antioxidant than in fillets stored with vitamin E. In this study the transfer of radicals from lipid oxidation to proteins and subsequent formation of protein-cross-links has been reported for the first time. The interaction between lipids and proteins were examined by both ESR and fluoroscence spectroscopy. A central esr free radical (g )signal was observed in both simple systems (methyl linoleate and pure amino acids) and complex systems (fish lipid and pure proteins (lysozyme, ovalbumin) or fish protein (myosin)). The esr signal reached a maximum within a week and then started to decline and with a concomitant increase in a pinkish yellow chromogen. This chromogen which was soluble in organic solvent and fluoresced at an excitation wavelength 360 nm and emission wavelength 420 nm and indicated the formation of protein cross-links. Synthetic (BHT, BHA) and natural (vitamins E, C) antioxidants were capable of preventing both the radical transfer and protein cross-linking. In this study lipoxygenase was isolated from mackerel flesh and its involvement in lipid oxidation mechanism was established. The molecular weight of partially purified lipoxygenase was 119,000 Daltons. This enzyme was capable of oxidising arachidonic acid to 12-hydroeicosatetraenoic acid (12-HETE), which was identified by HPLC. This 12-HETE was absent in pure arachidonic acid and in samples to which boiled enzyme was added. Conventional inhibitors, synthetic and natural antioxidants also inhibited the formation of 12-HETE, indicating the importance of lipoxygenase in fish lipid oxidation. During frozen storage, protein solubility decreased and the texture deteriorated in Atlantic mackerel stored for 3, 6, 12 and 24 months at -20°C and -30°C. There was an increase in peroxide value and TBARS; decrease in myosin ATPase activity a decrease in myofibrillar protein solubility in high salt concentration as well as formation of high molecular weight aggregates which showed low thermal stability and high G' and G" modulus values. There were significant differences (P < 0.01) between samples stored at -20°C and -30°C, with greater deterioration evident in samples stored at -20°C. Similarly, there were significant differences (P < 0.01) between samples stored with and without antioxidants; the samples stored without antioxidants deteriorated faster than samples stored with antioxidants. This suggests the involvement of lipid oxidation products in protein deterioration during frozen storage.
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Noble, Ronald. "Sensory methods used in meat lipid oxidation studies." Kansas State University, 2018. http://hdl.handle.net/2097/38563.
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Master of ScienceFood Science Institute
Kadri Koppel
Oxidation of meat decreases consumer acceptance and reduces market value making it an important problem for the meat industry. Odor and flavor of meat are significantly affected by lipid oxidation and researchers continue to explore new ways to control meat oxidation. Natural antioxidants, irradiation and oxygen treatments are major areas of research in meat lipid oxidation. In recent studies researchers have been exploring ways to extend shelf life of meat and in many case rely on sensory results. This report deals with sensory methods used to measure changes associated with treatments and outlines how researchers are using these methods.
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Hoyland, David Vernon. "Chemical methods for assessing lipid oxidation in food." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254588.
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Smith, G. "Lipid oxidation in S.E. Asian salted-dried fish." Thesis, University of Lincoln, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380661.
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Jenkins, Benjamin John. "The role of alpha oxidation in lipid metabolism." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/278025.
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Recent findings have shown an inverse association between the circulating levels of pentadecanoic acid (C15:0) and heptadecanoic acid (C17:0) with the risk of pathological development in type 2 diabetes, cardio vascular disease and neurological disorders. From previously published research, it has been said that both these odd chain fatty acids are biomarkers of their dietary intake and are significantly correlated to dietary ruminant fat intake. However, there are profound studies that show the contrary where they do not display this biomarker correlation. Additionally, several astute studies have suggested or shown odd chain fatty acid endogenous biosynthesis, most often suggested via alpha oxidation; the cleavage of a single carbon unit from a fatty acid chain within the peroxisomes. To better understand the correlations and interactions between these two fatty acids with pathological development, the origin of these odd chain fatty acids needed to be determined, along with confirming their association with the disease aetiology. To minimise animal & human experimentation we made use of existing sample sets made available through institutional collaborations, which produced both animal and human interventional study samples suitable for odd chain fatty acid investigations. These sample collaborations allowed us to comprehensively investigate all plausible contributory sources of these odd chain fatty acids; including from the intestinal microbiota, from dietary contributions, and derived from novel endogenous biosynthesis. The investigations included two intestinal germ-free studies, two ruminant fat diet studies, two dietary fat studies and an ethanol intake study. Endogenous biosynthesis was assessed through: a stearic acid infusion, phytol supplementation, and an Hacl1 knockout mouse model. A human dietary intervention study was used to translate the results. Finally, a study comparing circulating baseline C15:0 and C17:0 levels with the development of glucose intolerance. We found that the circulating C15:0 and C17:0 levels were not significantly influenced by the presence or absence of intestinal microbiota. The circulating C15:0 levels were significantly and linearly increased when the C15:0 dietary composition increased; however, there was no significant correlation in the circulating C17:0 levels with intake. Circulating levels of C15:0 were affected by the dietary composition and factors affecting the dietary intake, e.g. total fat intake and ethanol, whereas circulating C17:0 levels were found to be independent of these variables. In our studies, the circulating C15:0 levels were not significantly affected by any expected variations in alpha oxidation caused by pathway substrate inhibition or gene knockout. However, C17:0 was significantly related, demonstrating it is substantially endogenously biosynthesised. Furthermore, we found that the circulating C15:0 levels, when independent of any dietary variations, did not correlate with the progression of glucose intolerance when induced, but the circulating C17:0 levels did significantly relate and linearly correlated with the development of glucose intolerance. To summarise, the circulating C15:0 and C17:0 levels were independently derived; the C15:0 levels substantially correlated with its dietary intake, whilst the C17:0 levels proved to be separately derived from its endogenous biosynthesis via alpha oxidation of stearic acid. C15:0 was found to be minimally endogenously biosynthesised via a single cycle of beta oxidation of C17:0 in the peroxisomes, however, this did not significantly contribute to the circulating levels of C15:0. Additionally, only the baseline levels of C17:0 significantly correlated with the development of glucose intolerance. These findings highlight the considerable differences between both of these odd chain fatty acids that were once thought to be homogeneous and similarly derived. On the contrary, they display profound dietary, metabolic, and pathological differences.
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Vereb, Heather A. "Biomarkers of Lipid Oxidation in the Oral Cavity." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76887.
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Measuring lipid oxidation is useful as a means of monitoring oxidative stress, such as that induced by clinical conditions or environmental exposure. Characteristic volatile compounds, often with low threshold odors, are secondary products of lipid oxidation reactions. Metallic flavor in food and beverages has been linked with oxidation of lipids in the oral cavity. Breath, an emerging medium for analysis of internal condition, is one means of measuring the metal-induced lipid oxidation responsible for this flavor. This project analyzes the breath of human subjects, as well as lipid oxidation of in vitro samples to identify compounds responsible for producing metallic flavor, which result from the oxidation of lipids in the oral cavity. Because these analytes are found at extremely low (picomolar to nanomolar) concentrations, preconcentration of samples prior to gas chromatography-mass spectrometry analysis is crucial. This study utilizes both solid phase microextraction (SPME) and micromachined silicon micropreconcentrators to concentrate compounds in breath to optimize analysis.Master of Science
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Turner, Rufus. "Lipid oxidation by denatured haemproteins in heat-processed vegetables." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365990.
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Arnold, Andrew Richard. "Lipid oxidation in a model system and in meat." Thesis, University of St Andrews, 1989. http://hdl.handle.net/10023/14168.
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Lipid oxidation is the main factor which limits the shelf-life of meat when held under frozen storage. Research undertaken used pork phospholipid liposomes as a model for studying lipid oxidation in meat. Oxidation was followed by monitoring the decrease in the phospholipid unsaturated fatty acyl chains. It was found that the greater the level of unsaturation of the phospholipid fatty acyl chain the greater was their susceptibility to peroxidation. However, the results were not consistent and several reasons for the variation in rate are provided. At ambient temperatures copper (II) was found to be pro-oxidant in the peroxidation of liposomes. At temperatures below 0°C the prooxidant activity of copper (II) was significantly reduced. However copper again became highly pro-oxidant if sodium chloride was present. It is suggested that salt controls the copper ion concentration at sub-zero temperatures as the pro-oxidant activity of copper (II) is reduced on increasing the copper (II) concentration from 0.9 to 90 ppm. Other experiments found sodium nitrite and pholyphosphate to act as antioxidant and that liposome structure was an important factor in the rate of peroxidation. Four storage trials on pork burgers were undertaken to determine whether salt was also pro-oxidant in the stability of pork when held under frozen storage. The oxidative deterioration of the meat was followed by the following methods of analysis:- 1. The decrease in the unsaturated acyl chains of both total lipid and phospholipid. 2. The change in the colour parameters of the meat using reflectance spectroscopy. 3. The analysis of neutral lipid oxidation products by HPLC. 4. The organoleptic qualities of the pork using a trained panel of food assessors. The results from these storage trails showed that the deterioration of pork was minimised by storing the burgers at lower temperatures within the range 0 to -30°C. Salt was found to accelerate the oxidative deterioration of both uncooked and cooked pork when stored at -20°C. Nitrite was found to exhibit some antioxidant behaviour and reduce the pro-oxidant effect of salt.
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Sickler, Marsha Lynn. "Inhibition of Lipid Oxidation with Phosphates in Muscle Foods." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/9866.
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Lipid oxidation degrades the quality and decreases the shelf-stability of muscle foods. The depletion of phosphates prior to cooking may be a major factor in this undesirable reaction. Thus, the effects on lipid oxidation with the use of an encapsulate to protect the phosphates during raw storage was investigated.
Unencapsulated and encapsulated sodium tripolyphosphate (STP) and sodium acid pyrophosphate (SAPP), at a level of 0.5%, were compared to control samples in cooked, ground beef patties at 0 and 6 days. The unencapsulated and encapsulated treated samples were different (P<0.05) from the controls with an 81.1% to 89.7% improvement in the reduction of lipid oxidation. However, encapsulated phosphates did not decrease the level of oxidation beyond the unencapsulated treatment. This observation was attributable to the lack of a storage time prior to evaluating rancidity. Therefore, with an increase of precooked storage time, the 0.10% active encapsulated STP was essentially as effective as 0.20% unencapsulated STP for both 3 and 11 days.
Unencapsulated STP (0.3% or 0.5%), encapsulated STP (0.3% or 0.5% active), a blend of unencapsulated (0.3%) and encapsulated (0.2% active) STP, and a control treatment was incorporated in ground turkey breast and stored at 3°C for 0, 5, and 10 days. The treated samples were cooked to two different endpoint temperatures (74°C and 79°C) and stored at 3°C (4 and 24 hr) before cooking. An improvement of 77% and 80% was found in the reduction of Thiobarbituric Acid Reactive Substances (TBARS) with the 0.3% and 0.5% encapsulated STP, respectively, in comparison to the unencapsulated STP. The best results were seen with a shorter storage time (4 hr) prior to cooking and a higher endpoint temperature (79°C). The unencapsulated and encapsulated STP were compared to commercial antioxidant blends, Lemo-fos and Freez-Gard FP 15, at a level of 0.5%, to determine differences in their capabilities of lipid oxidation reduction. The encapsulated phosphate was lower (P<0.05) in TBARS (3.5 mg/kg) in comparison to the treatments which ranged from 15.6 to 20.4 mg/kg. However, the CIE a* values were higher in the encapsulated samples due to the decrease in lipid oxidation.
The effect of liquid nitrogen on TBARS values was investigated to identify a means of analyzing a large quantity of samples. The use of cryogenic freezing was not significantly different in TBARS in comparison with a fresh, unfrozen control. Raw and cooked ground turkey samples were submerged into liquid nitrogen and stored intact or immediately reduced in particle size to compare particle reduction effects on TBARS. The different particle reduction methods were not significantly different, although, the immediately reduced sample was more efficient in TBARS determination. The samples stored in an ultralow freezer (-80°C) for 14 and 33 days were not different (P>0.05).
Overall, when encapsulated STP is used with sufficient pre-cook storage time, lipid oxidation can be more effectively reduced than with the use of unencapsulated phosphates. The use of cryogenic freezing and ultralow temperature storage can also aid in the determination of lipid oxidation in large sample quantities due to the stability of TBARS values.Master of Science
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Narciso-Gaytan, Carlos. "Dietary lipid source and vitamin e influence on chicken meat quality and lipid oxidation stability." Thesis, [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2746.
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Škrabalová, Lada. "Hemoglobin-mediated oxidation of marine liposomes." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-216833.
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Cílem této práce bylo studium mechanismu oxidace lipidů katalyzované hovězím methemoglobinem a zhodnocení účinků různých experimentálních podmínek a antioxidantů (EDTA, askorbová kyselina, kávová kyselina, a-tokoferol, d-tokoferol, astaxanthin a L-askorbyl-6-palmitát) na methemoglobinem zprostředkovanou oxidaci lipidů v modelovém systému liposomů připravených z fosfolipidů. K monitorování oxidace lipidů při pH 5,5 a teplotě 30 °C bylo použito spotřeby kyslíku. Pro zhodnocení antioxidační aktivity v modelovém systému liposomů se ukázaly být důležitými faktory typ prooxidantu a koncentrace prooxidantu a antioxidantu. Dalšími důležitými faktory jsou struktura molekuly antioxidantu, jeho hydrofilita/lipofilita a umístění v systému. Všechny testované antioxidanty ve všech koncentracích (kromě koncentrace 0.1 % astaxanthinu and 0.1 % askorbyl palmitátu) inhibovaly oxidaci vyvolanou methemoglobinem. Účinnost antioxidantu stoupala s jeho zvyšující se koncentrací. Koncentrace 0.1 % astaxanthinu neměla žádný vliv na oxidaci liposomů. Koncentrace 0.1 % askorbyl palmitátu měla prooxidační efekt, který lze vysvětlit prooxidačním působením radikálu askorbylu, který může urychlit štěpení hydroperoxidů. Volné železo uvolněné z methemoglobinu se podílelo jen velmi málo na oxidaci liposomů, zatímco část prooxidační aktivity methemoglobinu byla přisouzena tvorbě singletového kyslíku (methemoglobin jako fotosenzitizátor). Antioxidační aktivita astaxanthinu, askorbyl palmitátu a tokoferolu byla z části přisouzena schopnosti zhášet singletový kyslík. Ovšem hlavním prooxidačním mechanismem methemoglobinu se ukázal být rozklad lipidových hydroperoxidů, tvorba volných radikálů a hypervalentních forem hemoglobinu. EDTA utlumila oxidaci liposomů díky chelataci přechodných kovů obsažených v liposomech a chelataci volného železa přítomného v methemoglobinovém roztoku. Velmi důležitým antioxidačním mechanismem (který vykazují askorbyl palmitát, askorbová a kávová kyselina) se ukázala být redukce hypervalentních forem hemoglobinu. Askorbová kyselina, kávová kyselina, tokoferoly a astaxanthin inhibovaly methemoglobinem zprostředkovanou oxidaci lipidů odstraňováním volných radikálů. Při použití peroxidu vodíku nebyl pozorován žádný vliv na oxidaci liposomů vyvolanou methemoglobinem. Působení vysoké teploty (tepelná denaturace) mírně utlumilo oxidaci. Významná inhibice oxidace byla pozorována u liposomů obsahujících TPP (triphenylphosphin), což značí, že je methemoglobinem vyvolaná oxidace liposomů závislá na přítomnosti již vzniklých lipidových peroxidů. Výsledky této práce přispívají k hlubšímu pochopení prooxidačních a antioxidačních mechanismů a faktorů, které ovlivňují oxidaci liposomálních roztoků, buněčných membrán a emulzí typu olej ve vodě stabilizovaných fosfolipidy.
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Pradhan, Arati S. "Diffusion of zinc through oxidized lipid bilayers." Virtual Press, 2000. http://liblink.bsu.edu/uhtbin/catkey/1166400.
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Egg phosphatidylcholine was oxidized by atmospheric oxygen under UV light for 16 hours, and the oxidized products formed were fractionated with high-pressure liquid chromatography in reverse phase. Three fractions that appeared at retention times of 19 minutes, 21 minutes and 24 minutes respectively (fraction 19, fraction 21 and fraction 24) were isolated and stabilized by reduction with triphenylphosphine. Zinc diffusion across 1-palmitoyl-2 oleoyl-sn-glycero-3-phosphocholine (POPC) liposome bilayers mixed with the isolated oxidized fractions was measured. The rate constant for zinc diffusion through the POPC liposome was highest in fraction 19 followed by fraction 21 and fraction 24.NMR data suggests that all oxidized fractions were derived from the major egg polyunsaturated PC, 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine. The primary oxidized product, fraction 24 contains a mixture of isomers in which the linoleoyl group has formed the 9-hydroxy-10,12-trans-cis diene and trans-trans diene or the 13-hydroxy12,10-trans-cis diene and trans-trans diene. The primary oxidized products on further oxidation, result in secondary oxidized products, contained in fraction 21 and fraction 19.Experimental data indicates that the major components of fraction 21 are the 9-hydroxy12,13-epoxy-l0-trans-monoene (and 13-hydroxy-9,10-epoxy-11-trans-monoene) and the major components of fraction 19 are the 9,12,13-trihydroxy-l0-trans-monoene (and 9,10,13-trihydroxy-1 l-trans-monoene).Department of Chemistry
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Shehadeh, Sandra C. "The Effects of Soy Protein and Isoflavones on Lipid Oxidation and Blood Lipid Profile on Humans Participating in Moderate Physical Activity." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/36112.
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The purpose of our study was to compare the effects of dietary soy protein and animal protein (casein) on plasma lipoprotein concentrations, and exercise induced oxidation in human subjects. Sixteen normocholesterolemic young men participated in 30 min of cycling at 70% VO2pk to induce plasma oxidation. Each subject then followed a 4wk dietary treatment replacing 33g animal protein in a self-selected solid food diet with either soy protein or casein. The exercise was then repeated and plasma lipoproteins and oxidation were compared. Soy protein and casein dietary treatments did not affect plasma concentrations. Our study therefore, suggests that in healthy normocholesterolemic individuals, 33g of soy protein does not effectively reduce plasma lipoprotein concentrations or exercise induced oxidation.Master of Science
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Ares, Mikko. "Effects of lipid oxidation on transcriptional regulation and cell death /." Stockholm, 1998. http://diss.kib.ki.se/search/diss.se.cfm?19980513ares.
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McMoneagle, Andrew. "Antioxidant behaviour in photo-oxidation studies of model lipid compounds." Thesis, University of the West of Scotland, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311777.
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Baek, Naerin. "Effects of Natural Antioxidants on Lipid Oxidation of Menhaden Oil." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/19214.
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Preventing oxidative deterioration of fish oil is a significant challenge for the food industry. Natural antioxidants are widely incorporated into foods and oils to prevent oxidation and extend shelf life. The goal of the study is to investigate the activity of novel antioxidants in menhaden oil and to develop optimum formulations containing mixed tocopherols to control oxidation of menhaden oil. Alpha tocopherol, gamma tocopherol, and delta tocopherol in menhaden oil were found at 0.18mg/g, 0.37mg/g, and 0.14mg/g, respectively, using HPLC analysis. Teng Cha extract effectively delayed oxidation of menhaden oil (MO) when stored at 40°C for eight days by measuring primary oxidation products and secondary oxidation products. The combinations of Teng Cha extract and rosemary extract and combinations of ascorbyl palmitate, citric acid, Teng Cha extract and rosemary extract more effectively improved stability of MO containing mixed tocopherols than Teng Cha extract alone at 40°C storage for eight days by measuring primary oxidation products and secondary oxidation products. From this study, Teng Cha extract can be used as a potential natural antioxidant in food industry, especially in combinations with rosemary extract and tocopherols, extending shelf life of menhaden oil.Master of Science in Life Sciences
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Zopyrus, Nadia. "On the Origin of Secosterols Upon Oxidation of Cholesterol." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35885.
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Cholesterol is one of the most abundant lipids in the body, and like all unsaturated lipids, it can be oxidized by a variety of reactive oxygen species (ROS). Lipid peroxidation is one of the main pathways by which ROS induce oxidative damage, and has been linked to neurodegenerative and cardiovascular diseases. In 2003, Wentworth et al. detected both 3β-hydroxy-5-oxo-5,6-secocholestan-6-al (secosterol-A) and its intramolecular aldolization product 3β-hydroxy-5β-hydroxy-B-norcholestane-6β-carboxaldehyde (secosterol-B) in human atherosclerotic plaques – compounds which, at the time, were only known to be formed by cholesterol ozonolysis.
However, our group has shown that cholesterol 5α-hydroperoxide, which is the product of the reaction of cholesterol with singlet oxygen, can undergo acid-catalyzed Hock fragmentation to generate secosterol-A and -B as well. Nevertheless, cholesterol 5α-hydroperoxide readily rearranges to a more thermodynamically stable cholesterol 7-hydroperoxide. Herein we show that cholesterol 7-hydroperoxide, the main product of cholesterol autoxidation, can also undergo acid-catalyzed Hock fragmentation that gives rise to electrophilic species with similar chromatographic characteristics to those that were allegedly identified as secosterol-A and -B.
We also proposed to prepare authentic products of the Hock fragmentation of cholesterol 7-hydroperoxide by subjecting Δ⁶’⁷-cholesterol to ozonolysis. Herein, we explore the limitations and complications of Δ⁶’⁷-cholesterol ozonolysis as well as cholesterol 7-OOH Hock fragmentation which both resulted in unexpected (unprecedented) products.
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Gaggini, Paul. "Anti-oxidants and peroxidation of model lipid compounds." Thesis, University of the West of Scotland, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360232.
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Aaneby, Jorunn. "Iron Catalyzed Lipid Oxidation in Emulsions and the Influence of Antioxidants." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bioteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19014.
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Lipids from marine sources contain high amounts of omega-3 fatty acids which are known to have several beneficial effects on human health. Their use as food ingredients is however limited due to their high susceptibility to lipid oxidation resulting in development of rancidity. Liposomes prepared from marine phospholipids have previously been used as a model system to study lipid oxidation by measurement of oxygen consumption. It was of interest to study lipid oxidation by this method in oil-in-water emulsions which can be considered to be more similar to foods. Incorporation of antioxidants in foods is an approach to increase the stability of foods containing omega-3 fatty acids. Emulsions were used as a model system to study the influence of EDTA, citric acid, caffeic acid, propyl gallate, α-tocopherol, ascorbic acid, β-carotene and astaxanthin on iron catalyzed lipid oxidation. Crude herring oil was washed with water to remove impurities. Analyses showed that impurities including carbonyl compounds and carotenoids were removed by the washing, while the oxidation level of the oil slightly increased. The herring oil was used for preparation of emulsions with herring phospholipids as emulsifier by the use of a dispersing tool where increased dispersing time resulted in larger oil droplets with a wider size distribution.Iron catalyzed oxidation of lipids in the emulsions occurred at a lower rate than what has previously been measured in liposomes, but the initial reaction between lipid hydroperoxides and Fe2+ occurred at the same rate in the two systems. The use of soy lecithin as emulsifier inhibited oxidation of lipids in the emulsions. Interactions between iron and antioxidants had a major impact on oxidation in the emulsions. EDTA and citric acid completely inhibited the oxidation when they were added in twice the ratio to iron. Citric acid was not able to inhibit the initial reaction between lipid hydroperoxides and Fe2+ which was thought to be due to its inability to bind Fe2+. Caffeic acid and α-tocopherol enhanced the oxidation rates by reducing Fe3+ to the more catalytically active Fe2+. The prooxidative activity of caffeic acid was significantly greater than that of α-tocopherol. Caffeic acid, α-tocopherol and propyl gallate inhibited the initial reaction between lipid hydroperoxides and Fe2+ to a similar degree which was thought to be related to their free radical scavenging and metal chelating activities. Propyl gallate was also able to reduce the oxidation rates. Ascorbic acid was itself oxidized by Fe2+ and Fe3+ which resulted in increased initial consumption of oxygen, but not increased oxidation of the lipids. Ascorbic acid was able to decrease the prooxidative activity of α-tocopherol by regeneration of α-tocopherol from the α-tocopheroxyl radical. β-Carotene and astaxanthin showed only minor influences on lipid oxidation in the emulsions.
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Bowen, Sarah Elizabeth. "Lipid oxidation in biopolymer matrices in their glassy and rubbery states." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428925.
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Sarkardei, Samiramis. "Mechanisms of lipid oxidation and safety assessment in underutilised fish species." Thesis, University of Surrey, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418255.
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Eriksson, Louise. "Method development and optimization for determination of lipid oxidation in emulsions." Thesis, Uppsala universitet, Analytisk kemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-296263.
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Lipid emulsions in parenteral nutrition’s consist of two immiscible liquids described as oil in water phase. The oils in the emulsions can start to oxidize and make it become rancid. The oxidation can be measured for peroxide value, anisidine value and for free fatty acids (FFAs) as primary- and secondary oxidation products. This master thesis presents an analytical method used for analysis of oxidation products. The aim of this project was to come up with a method to separate the oil from the water-phase, to a sufficient yield and as pure as possible for analysis in a spectrophotometer called FoodLab fat. During the way experiments regarding stability of oils and finally a stability study on emulsions were done. Starting the separation experiments with ethanol to break the emulsion, this turned out to be the best way to go. Further investigation through extractions with 2- propanol/isooctane and ethanol/heptane were tested. The method needed to be simple, easy to use and not too time-consuming but still be repeatable and reliable. To optimize the separation, different centrifugation volumes, forces and times were tested. The results showed that in order to get the best separation the centrifugation volume and force cannot be too large or too small. The final method proved to be successful for the use as research method and to be able to see trends of oxidation for the products. Further research and validation of the instrument and the method needs to be done before it can be used as a quality control method.
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Tabee, Elham. "Lipid and phytosterol oxidation in vegetable oils and fried potato products /." Uppsala : Department of Food Science, Swedish University of Agricultural Sciences, 2008. http://epsilon.slu.se/200892.pdf.
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Ng, Su Chuen. "Effects of accelerated aging on lipid oxidation in quinoa (Chenopodium quinoa)." Online version, 2003. http://www.uwstout.edu/lib/thesis/2003/2003ngs.pdf.
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MARTINEZ, FERNANDEZ ALMA ESTEFANIA. "ANALYSIS OF LIPID AND PROTEIN OXIDATION STATUS IN HEART FAILURE PATIENTS." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/700135.
Full textAbstract:
Increasing body of evidence supports that oxidative stress is involved systolic and diastolic myocardial dysfunction in HF. Indeed, it has been well established an association between cardiac remodeling (hypertrophy, apoptosis or contractile dysfunction) and oxidative stress. Hence, the identification, quantification and fully characterization of oxidized biomolecules present in the plasma of HF patients can contribute to understand the mechanisms responsible for disease development but also as biological markers. However, the classic biomarkers of oxidative stress identified in HF do not provide thorough information but report about a general oxidative stress status. For a better understanding of the pathology of HF it is needed to unveil not only protein and lipid targets of oxidative damage but also the residues undergoing the modification within the protein and the structure of the oxidation products. Analysis of all of these oxPTMs and lipid peroxidation products by mass spectrometry is extremely challenging. Indeed, oxPTMs tend to occur randomly on a number of susceptible residues and proteins, making it extremely difficult to define all protein species. Along this project, plasma samples from HF patients belonging to different NYHA groups (from class I to class IV) have been employed to identify oxidized biomolecules as potential biomarkers of HF, and eventually subjected to several plasma prefractionation strategies combined with high-throughput untargeted and targeted mass spectrometry techniques. Consequently, part of this project has been focused on the study of oxidative modifications in human serum albumin (HSA), the most abundant protein in the circulatory system, associated with HF. HSA is involved in a wide range of biological functions and, due to its long half-life and high concentration in plasma, HSA is highly sensitive to undergo oxPTMs that may lead to its functional loss, thus contributing to the progression of HF. Taking advantage of the high abundance of HSA, we relatively quantified for the first time plasma levels of cysteinylated HSA (cys-HSA) and also levels of early glycated HSA (GA), and we observed a significant increase in HF patients with respect to the healthy subjects. A positive correlation between the levels of both isoforms and HF severity was highlighted whereas the abundance of total HSA showed a tendency to decrease when raising the severity degree of HF. For a deeper characterization of GA, we elucidated for the first time the early glycation pattern of HSA associated to HF by means of the newest generation of Tribrid MS instruments. Lys233 and lys525 were observed as the two most abundant glycated amino acids (79% and 13% respectively). Considering that further modifications of GA, such as rearrangement, oxidation, polymerization, and cleavage give rise to irreversible conjugates, called advanced glycation end products (AGEs), we also aimed to unveil the plasma advanced glycation pattern associated to HF. In this case, lys20, arg98, and lys402 emerged as the three most abundant carboxymethylated residues. Therefore, the results suggested that on one hand lys233 and lys525, and on the other lys20, arg98 and lys402, might represent the main potential therapeutic targets to reduce GA and AGE-HSA levels in HF patients, respectively. Besides the study of oxidized isoforms of HSA, we also tried to identify other less abundant advanced glycation and lipoxidation end products (AGEs and ALEs) in plasma by means of an enrichment strategy based on the ability of RAGE receptor to bind AGEs and ALEs. Due to the relevance of HSA in circulation, we have also evaluated the potential causal role of GA in the etiopathogenesis of HF. Hence, we pursued to evaluate the biological effects of GA on cardiac myocytes. Results highlighted that GA modulates in vitro the cardiomyocyte expression of inflammatory cytokines such as IL-6 or TNF-α. Furthermore, we reported that GA induces oxidative stress and oxidative modifications of a multitude of cellular proteins within cardiac myocytes. In addition, GA modulates the secretion of several cardiac proteins involved in response to stress biological processes. On the other hand, lipids play a crucial role in physiological processes and phospholipid disruption may participate in cardiovascular disease events, therefore the phospholipidome profiling has emerged as a powerful tool to explore novel biomarkers and mechanisms in several pathologies. Hence, we have also studied for the first time the plasma phospholipidome of HF patients. In this pilot study, we have applied both untargeted and targeted (MRM) strategies together with fractionating methods to separate the phospholipid content from the rest of plasma components, in order to decrease the heterogeneity and complexity of this biological matrix. The results suggested that HF plasma phospholipid signatures were gender-specific. In the case of females, several PE species were more abundant in HF than in the control group. On the contrary, male HF patients mainly showed a higher abundance of LPC species when compared to the male control group. Additionally, lipidomic approaches (LC-MS/MS and PRM) have been carried out to define for the first time a circulating oxidative lipid pattern associated with HF. In this case, we have focused on long- and short-chain products of lipid peroxidation since their identification and characterization in the pathology of HF were still lacking. Promising results have been pinpointed so far: we have detected 9 lipid peroxidation products (full-chain oxidized lipids together with fragmented species). In conclusion, the results gathered along this Ph.D. project provide evidence at the molecular level of the mechanisms associated to oxidative stress and oxidative damage underlying the development and progression of HF, thus contributing to a better understanding of the pathology. Indeed, the elucidation of specific modified residues within key circulating proteins such as HSA, or the characterization of long- and fragmented-chain lipid peroxidation products present in HF plasma samples reported in this thesis may pave the way to new therapies to reduce and treat HF. We have also contributed to expand the awareness of the biological effects of GA in the cardiac context. Additionally, this project has pointed out a gender-dependent adaptation of the plasma phospholipidome occurring in the pathology of HF, highlighting that gender is a major and often underestimated factor that should be carefully considered when screening lipidomes or proteomes of pathological processes. Finally, we have demonstrated that either proteomic or lipidomic technologies can provide deep biological insight into human health and disease.
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Bothma, Karien. "The involvement of lipid and protein oxidation in hypertension : the SABPA study / Karien Bothma." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8652.
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Oxidative stress, caused by increased levels of reactive oxygen species (ROS)and reactive nitrogen species (RNS) and/or a decrease in antioxidant capacity, can result in the oxidation of various bio-molecules, such as proteins, lipids and deoxyribonucleic acid (DNA). These oxidized bio-molecules may contribute to pathologies such as cardiovascular diseases, neurodegenerative disorders and cancer. The Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study was initiated in 2008 to investigate the coping styles and catecholamine metabolic markers of Africans, contributing to their higher sympathetic output and poorer psychosocial wellbeing. This study forms part of the SABPA study, but with a specific aim to investigated lipid and protein oxidation markers in hypertensive Africans versus their normotensive counterparts.
Analytical methods for the quantification of specific lipid and protein oxidation markers were optimized and validated. Urine samples from 172 urbanized black South Africans were collected and 3-nitrotyrosine (3NT) and thiobarbituric acid reactive substances (TBARS) were quantified in these samples, using the optimized spectrophotometric and LC-MS/MS methods. Statistical analyses showed that in both males and females, TBARS and 3NTcorrelated with each other. In males, 3NT also correlated with physical activity level (PAL) and C-reactive protein (CRP), while TBARS also correlated with body mass index (BMI). In females 3NT correlated with BMI, while TBARS correlates with PAL. These correlations meant that they could influence the calculations of the true effect of 3NT and TBARS levels between normotensive and hypertensive subjects. After analyses of covariance (ANCOVA) analyses it was determined that the hypertensive male subjects had higher TBARS values than the normotensive male subjects did (p-value = 0.03) and the normotensive female subjects had higher 3NT levels compared to the hypertensive female subjects (p-value = 0.04).
These results partially supported the hypothesis that that elevated concentrations of specific urinary lipid and protein oxidation markers will be observed in the
hypertensive test subjects compared to their normotensive counterparts. The results also indicated that there were indeed a difference in lipid and protein oxidation between hypertensive and normotensive subject.Thesis (MSc (Biochemistry))--North-West University, Potchefstroom Campus, 2013
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Jenschke, Blaine Edward. "Chemical, color, and sensory attributes of sorghum bran-enhanced beef patties in a high oxygen environment." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3348.
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Bottom rounds were shipped to the Rosenthal Meat Science and Technology Center, ground and enhanced with one of the following predetermined treatments: control; 0.4% sodium phosphates and 0.3% salt; 0.25% sorghum bran; 2.0% sorghum bran; 0.25% sorghum bran, 0.4% sodium phosphates and 0.3% salt; and 2.0% sorghum bran, 0.4% sodium phosphates, and 0.3% salt. The ground beef was formed into 226 g ground beef patties, packaged in an 80% O2 and 20% CO2 gaseous environment, and stored under retail display at 4 degrees for 0, 3, 6, or 9d. Measurements to determine rate and extent of oxidation, rate of discoloration, and sensory characteristics were taken to evaluate the effectiveness of sorghum bran.
Patties containing the highest amount of sorghum bran had the lowest TBARS values over 9 days of storage, lower a* values, greater amounts of discoloration, darker lean color, and less cook loss (P<0.05) than control patties. Patties enhanced with the highest level of sorghum bran had lower beefy/brothy and bloody flavor aromatics, higher sorghum flavor, more bitter and burnt aftertaste, and more sandy/gritty textures (P<0.05) when compared to control patties. Patties containing the low amount of sorghum had lower TBARS values (P<0.05), but similar amounts of cook loss as the control patties. Patties containing a low sorghum level, 0.4% sodium phosphates (SP) and 0.3% salt (S) had lower (P<0.05) amounts of cook loss when compared to control patties. Patties containing low amounts of sorghum were similar to control patties in terms of redness while the addition of low sorghum, SP, and S decreased (P<0.05) the degree of redness. Patties containing low amounts of sorghum bran had similar amounts of discoloration compared to control (CONT) patties. Also, these had less bloody flavor aromatics (P<0.05), but were similar in sorghum flavor aromatics and bitter taste when compared to control patties.
The addition of sorghum bran at low levels can retard oxidative rancidity in ground beef patties without causing detrimental color changes and negatively affecting sensory attributes, while patties enhanced with 2% sorghum bran have extensive discoloration and undesirable sensory attributes.
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Prima-Hartley, Valerie Georgette Bernadette. "Lipoxygenase activity in model food emulsion systems." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267669.
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Chae, Sung Hee. "Conjugated linoleic acid reduces lipid oxidation in irradiated, cooked ground beef patties." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/5983.
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This study was conducted to examine the antioxidative effect of conjugated linoleic acid (CLA) in irradiated, cooked ground beef patties. The hypothesis was that CLA would be retained during irradiation and would reduce lipid oxidation that is caused by irradiation. The objective was to evaluate the effects of CLA alone and in combination with irradiation on lipid oxidation, fatty acid composition, cooking loss, moisture and fat content, and trained panel sensory evaluations of beef patties. CLA was added at 0, 1, 2, or 4% level during the grinding process. Addition of CLA during the grinding process increased CLA cis-9,trans-11 and CLA trans-10,cis-12 isomers in both irradiated and non-irradiated cooked ground beef patties (irradiated at 1.6 kGy) (P = 0.0001). Weight loss during cooking was greater in irradiated beef patties than in non-irradiated patties (P = 0.004). Irradiation reduced the serumy/bloody aromatic attribute and increased browned aromatic attribute, browned aftertaste, and wet dog/hairy aromatic attribute (P < 0.05). There was no significant main effect of irradiation on the basic tastes. The linoleic acid, CLA cis-9,trans-11, and CLA trans-10,cis-12 were decreased by irradiation (P < 0.05). Although irradiation decreased the CLA isomers, higher percentages of CLA isomers were retained in irradiated patties containing a 4% free fatty acid preparation of CLA (FFA-CLA), reflecting the ability of the FFA preparation to reduce lipid oxidation that is caused by irradiation. The thiobarbituric acid reactive substances (TBARS) values were significantly higher in irradiated, cooked ground beef patties than in non-irradiated ground beef patties (P = 0.004). Although the FFA-CLA was effective in reducing lipid oxidation that is caused by irradiation, it increased painty aromatic attribute, bitter taste, and astringent aftertaste due to the soapy flavor of the free fatty acid (all P < 0.05). The FFA-CLA decreased cooked beef/brothy and serumy/bloody aromatic attribute and browned aftertaste (all P < 0.05). The 1% triacylglycerol (TAG) preparation of CLA reduced TBARS in irradiated, cooked patties to levels seen in control, non-irradiated patties. The 1% TAG concentration also provided good retention of CLA in the cooked ground beef.
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Jayasingh, Preetha. "Prevention of Pigment Deterioration and Lipid Oxidation in Ground Beef and Pork." DigitalCommons@USU, 2004. https://digitalcommons.usu.edu/etd/5506.
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Fresh beef was modified-atmosphere packaged in carbon monoxide or oxygen to prolong red surface color. After comparison of several packaging method using carbon monoxide, steaks pretreated with 5% carbon monoxide for 24 hours and then vacuum packaged had the best combination of color and microbial stability (5 weeks), with the least potential for carbon monoxide inhalation.
In the evaluation of ground beef in high-oxygen, modified-atmosphere-packaging, thiobarbituric-acid numbers increased over time, and the flavor was disliked slightly after 6 or 10 days of storage at 2° Celsius.
The antioxidant effect of milk-mineral was tested in raw and cooked ground pork stored refrigerated or frozen. Thiobarbituric-acid numbers were low for all raw treatments. For cooked ground pork, thiobarbituric-acid numbers were lower for samples with milk-mineral or sodium-tripolyphosphate, compared to control or samples with butylated-hydroxytoluene. Sodium-tripolyphosphate, a type 2 antioxidant (iron chelator), was also very effective in preventing heme degradation during refrigerated storage.
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Jose-Cunilleras, Eduardo. "Effect of exercise and of meals of differing starch content on glucose kinetics and muscle glycogen utilization and replenishment in horses." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1091482764.
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Thesis (Ph. D.)--Ohio State University, 2004.Document formatted into pages; contains 181 p. Includes bibliographical references. Abstract available online via OhioLINK's ETD Center; full text release delayed at author's request until 2005 Aug. 6.
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Mannon, Adria G. "Preventing Oxidation of Dairy Powders Using Oxygen Removal Packaging." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/35970.
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Three types of dried milk (whole, nonfat, and buttermilk) were packaged in a modified atmosphere with a novel palladium-based oxygen removing catalyst and stored for eight weeks at 50°C. Powders stored in air with no catalyst and powders stored with the catalyst in an atmosphere modified to contain 5.7% hydrogen in nitrogen were evaluated by instrumental, chemical, and sensory methods.
Hexanal concentrations were measured weekly using solid phase microextraction (SPME) and gas chromatography (GC) to compare the degrees of oxidation in the powders stored with the catalyst to those stored without it. Color changes were also monitored weekly using Hunterâ s L-, a-, and b-values. At the end of the eight-week period, a paired comparison sensory test was used to ascertain if the catalyst had an effect on odor. Anisidine values were also measured at this point to determine levels of oxidation in the powders.
No significant difference was found in levels of oxidation between samples packaged with and without the catalyst in the modified atmosphere. At the end of eight weeks, the average hexanal concentration in the whole milk powder stored with the oxygen scavenger was 1.19 ± 0.20 ppm, while the average hexanal concentration in the air-packed whole milk powder was 1.06 ± 0.08 ppm. The average hexanal concentrations for the buttermilk stored with the catalyst and without were 0.84 ± 0.18 and 0.79 ± 0.15 ppm, respectively. In the nonfat milk powder, the sample stored with the catalyst had an average hexanal concentration of 0.91 ± 0.14 ppm and the sample stored in air without the catalyst had an average hexanal concentration of 0.83 ±0.20 ppm. Difference testing by volunteer sensory panelists also revealed no significant differences.
It was expected that the milk powders stored with the catalyst in the modified atmosphere would have lower levels of oxidation and off-odors at the end of the eight weeks. However, the treatment ultimately resulted in no chemical or sensory differences. Thus, the catalyst proved ineffective in the given conditions. This could be due to a loss of the hydrogen required for the catalyst to function as time progressed or a lack of significant oxidation under the conditions employed.Master of Science in Life Sciences
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Osborn, Anna. "Measurements of Human Plasma Oxidation." Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1426.
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The oxidation of lipids and antioxidants has been extensively studied in human plasma but little attention has been given to how plasma proteins are oxidised. Proteins make up the majority of biomolecules in cells and plasma and therefore are the most likely reactants with oxidants and free radicals. Previous studies in the laboratory had shown that peroxyl radicals generated by the thermolytic decay of 2-azobis (2-amdinopropane) dihydrochloride (AAPH) generated significant amounts of protein hydroperoxides, but only after a six hour lag period. In this study the existence of the six hour lag period was confirmed and shown by dialysis of the plasma to be due to the presence of low molecular weight antioxidants. The addition of both uric acid and ascorbic acid to the dialysed plasma restored the lag phase suggesting that in vivo these antioxidants act to prevent protein hydroperoxide formation. Lipid oxidation was also observed in the plasma but only after a two hour lag phase. This was the first time lipid oxidation has been observed in the absence of protein oxidation. The lipid lag phase was also abolished by dialysis of the plasma and restored by the addition of ascorbic acid and uric acid. The kinetics of tocopherol loss suggests that the tocopherol radicals act to inhibit lipid oxidation by transferring the electrons to the water-soluble ascorbate. The loss of ascorbate appears to cause the formation of a tocopherol radical mediate the lipid peroxidation process. Overall the data shows ascorbic acid scavenging the peroxyl radicals while uric acid acts to reduce the overall AAPH generated radical flux. In a separate investigation, the production of protein-bound DOPA (PB-DOPA) on albumin during X-ray radiolysis and copper mediate Fenton oxidation was investigated using a fluorescence based derivatisation method (ED-DOPA), which was compared with the more specific acid hydrolysis and HPLC analysis method. The ED-DOPA method consistently gave a much higher reading that the HPLC based methods, suggesting that the ED-DOPA method was measuring DOPA plus DOPA oxidation products. This was confirmed by oxidising X-ray radiolysis generated PB-DOPA with Cu++ to cause DOPA oxidation. The Cu++ treatment drastically increased the level of signal given by the ED-DOPA assay while HPLC analysis showed all the DOPA had been oxidised.
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Haynie, Kimberly Rebekah. "The Role of Neuropeptide Y Y1R in Skeletal Muscle Lipid Metabolism." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/32270.
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The Hulver laboratory has recently found that the neuropeptide Y Y1 receptor (NPY Y1R) mRNA expression is elevated in skeletal muscle of obese humans (Hulver, unpublished). The goal of this research is to study the role of the NPY Y1R in skeletal muscle lipid metabolism. Rat L6, mouse C2C12, and human primary myotubes were incubated in 14C palmitate labeled fatty acid oxidation medium containing 80ng/mL, 250ng/mL, and 500ng/mL of NPY and for a three hour period. Experiments were repeated with the addition of 17mg/mL diprotin A to each NPY treatment. Fatty acid oxidation (FAO) and the percentage of lipids stored within the myotubes as diacylglyceride (DAG) and triaclyglyceride (TAG) were measured. Analyses were repeated in rat L6 and mouse C2C12 following a three hour incubation in 14C palmitate labeled fatty acid oxidation medium containing 1µg/mL, 10µg/mL, and 50µg/mL of the NPY Y1R ligand, [Leu31, Pro34] neuropeptide Y (Bachem, Torrance, CA).
Incubation of human primary myotubes in NPY treatments with the addition of diprotin A significantly increased TAG accumulation (p< 0.05). Mouse C2C12 mytoube incubation in 500ng/mL NPY with diprotin A increased FAO (p 0.05). All other NPY and NPY Y1R ligand treatments in had no significant effect on FAO or the accumulation of TAG and DAG.
Master of Science
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Ginsburg, Shoshana Rivka. "Extraction of Lipid Soluble Antioxidants from Rosemary Leaves Using Vegetable Oils." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563290049617458.
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Ayoub, Pierre. "Molecular dynamics study of pyrene excimer formation and oxidation in lipid bilayer models." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE038/document.
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Nous proposons une nouvelle approche pour déterminer le coefficient de diffusion dans des membranes lipidiques se basant sur la formation d'excimères. Alors que les autres modèles statistiques considèrent le système comme un ensemble de points sur un réseau, nous utilisons un modèle à gros grain afin d'étudier des bicouches lipidiques simulées à l'aide du champs de force Martini. Nous déterminons le taux de réaction dépendant du temps à partir des probabilités de survie obtenues a posteriori à l'aide des trajectoires numeriques des bicouches symétriques de DOPC (1,2-Dioleoyl-sn-glycero-3-phosphocholine) et POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) simulées à 283 K et 293 K respectivement. Les dynamiques de collision sont obtenues en distinguant virtuellement les molécules simulées. Les sondes fluorescentes sont supposées semblables aux lipides, et par conséquent, ne modifient pas la dynamique. Nous obtenons une expression générale pour la probabilité de survie en combinant approximation des paires indépendantes et propriétés d'échelle, mais aucune hypothèse n'est faite pour le taux de formation d'excimère. En superposant les intensités d'émission de fluorescence normalisées, déterminées numériquement, aux courbes de titrations expérimentales, nous obtenons deux ensembles de résultats pour le coefficient de diffusion latéral, selon que l'association entre feuillets est autorisée ou pas. Nous utilisons un rayon de capture de 0.5 nm, la distance à partir de laquelle les deux sondes réagissent pour former un excimère. En comparant la dynamique Martini aux expériences de fluorescence, il est possible d'estimer le facteur d'accélérationWe propose a novel approach to extract the lateral diffusion coefficient in lipid bilayers using excimer formation. In contrast to previous statistical models that modeled the system as points undergoing jumps from site to site on a lattice, we use coarse-grained molecular dynamics to study lipid bilayers simulated using the Martini force field. We derive time dependent reaction rates from survival probabilities obtained a posteriori from numerically generated trajectories of symmetric DOPC (1,2-Dioleoyl-sn-glycero-3-phosphocholine) and POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) bilayers at 283K and 293K respectively. Collision dynamics are determined by virtually relabeling the simulated molecules. The fluorescent probes are assumed to behave like ordinary membrane lipids and therefore the dynamics remain unaffected. We derive a generalized expression for the survival probability combining independent pairs and size scaling assumptions, but no assumption is made regarding the kinetic rate of the excimer formation process. By fitting the numerically determined normalized fluorescence emission intensities to experimental titration curves, we obtain two sets of results for the lateral diffusion coefficients depending whether interleaflet excimer association is allowed or not. We use a capture radius of 0.5 nm, the distance at which the probes react to form excimers. By relating Martini dynamics to real fluorescence experiments, we estimate the numerical Martini acceleration factor. We also study mixtures of oxidized-non oxidized DOPC and POPC bilayers using a hydroperoxidized model of these lipids for different concentrations of the oxidized component (3.1%, 25% and 50%). Using pair correlation functions, we extract structural information on the systems and determine whether the two components are prone to mixing or not. Finally, we calculate the thermodynamic mixing parameters within the framework of the virial expansion
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Bee, Cheah Poh. "High pressure effects on lipid oxidation in rendered pork fat and minced pork." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320189.
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Cheng, Yu-Shiuan. "POLYUNSATURATED LIPID OXIDATION PRODUCTS AND THEIR BIOLOGICAL ACTIVITIES: SYNTHESIS, GENERATION, EFFECTS AND PROTECTION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1553850446781064.
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Telles, Scott Gerard. "Change in zinc permeability of lipid bilayers as a function of fluidity and oxidation." Virtual Press, 1997. http://liblink.bsu.edu/uhtbin/catkey/1061869.
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The main goal in my project was find out if the rate of zinc crossing the bilayer was either due to the fluidity of vesicles or the level of oxidation of the vesicles.To measure the oxidation a simple procedure called the TBA Test was used to measure each PC tested. The fluidity measurement was a calculation using the temperature the vesicles went from gel to liquid crystalline phase and the experimental temperature.Measuring the rate at which zinc crossed the bilayer was done using spectral changes that occur as zinc binds with APIII, a metal chelator entrapped inside the vesicles. To measure these rates we used k', the rate constant at which zinc is crossing the bilayer at a certain concentration and k, the second order diffusion rate constant which is the slope of k' vs. [Zn].The rates at which zinc was crossing the bilayer for each PC was then compared to the fluidity and oxidation levels for each PC. There was no direct correlation between the rates and fluidity but there was a good linear correlation between the rates and oxidation.So it seemed as if oxidation was the main reason zinc was crossing the bilayer so we wanted to see if our measurements could be obtained by biological cells. The comparison showed that rates obtained by biological cells can only be matched by the vesicle models when there oxidation levels are found to be high.In conclusion we believe that the reason zinc is crossing the bilayer is due to oxidation that occurs to the vesicle and as oxidation increases so do the rates at which zinc crosses the bilayer.Department of Chemistry
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Keceli, Turkan. "Antioxidant and antimicrobial activity of olive oil phenolics." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325073.
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Amft, Jonas [Verfasser], Karin [Akademischer Betreuer] Schwarz, and Eckhard [Gutachter] Flöter. "Physico-chemical properties of extrudates and their relation to lipid incorporation and lipid oxidation / Jonas Amft ; Gutachter: Eckhard Flöter ; Betreuer: Karin Schwarz." Kiel : Universitätsbibliothek Kiel, 2020. http://d-nb.info/1215571526/34.
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Webster, Janet B. "Changes in Aromatic Chemistry and Sensory Quality of Milk Due to Light Wavelength." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/29715.
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Gas chromatography (GC) and gas chromatography olfactometry (GCO) was used to determine the effect of specific light wavelengths on light oxidation in milk. The most damaging wavelengths to milk quality appear to be the UV (200-400 and 395 nm) and short visible (463 nm) wavelengths. However, exposure to 610 nm also appears to be damaging.
GC and GCO were also used to look at the efficacy of film over-wraps made from iridescent films. Single-layer over-wraps were not as effective in reducing light oxidation as multi-layer film over-wraps. Single-layer over-wrap treatments had higher numbers of odor-active compounds than multi-layer over-wrap treatments with a number of odor-active compounds detected consistently in single-layer over-wrap treatments but not in the multi-layer over-wrap treatments. Concentrations of volatile compounds were slightly lower in the multilayer treatments.
Multi-layer film over-wrap treatments were tested for light oxidation flavor intensity with a balanced incomplete block multi-sample difference test using a ranking system and a trained panel. Packaging over-wraps limited the production of light oxidation flavor in milk over time but not to the same degree as the complete light block. Blocking all visible riboflavin excitation wavelengths was better at reducing light oxidation flavor than blocking only a single visible excitation wavelength.
A method to determine light oxidation in oil using Fourier Transform Infrared (FTIR) spectroscopy was established and preliminary data is presented.Ph. D.
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Nanthirudjanar, Tharnath. "Studies on the Ameliorating Effects of Oxygenated Fatty Acids on Lipid Metabolism." Kyoto University, 2013. http://hdl.handle.net/2433/180513.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第17896号
農博第2019号
新制||農||1017(附属図書館)
学位論文||H25||N4792(農学部図書室)
30716
京都大学大学院農学研究科応用生物科学専攻
(主査)教授 菅原 達也, 教授 左子 芳彦, 教授 澤山 茂樹
学位規則第4条第1項該当
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Chido, Chakanya. "Fatty acid composition, colour stability and lipid oxidation of mince produced from fresh and frozen/thawed fallow deer meat." Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/2479.
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The aim of the study was to determine the fatty acid composition, colour stability and lipid oxidation of fresh mince produced from fallow deer and to evaluate the effect of frozen storage duration on the retail display shelf life of the mince. A total of 31 fallow deer carcasses were used in the study. After cooling for 24hrs, the carcasses were deboned, external fat from the fore and hindquarter muscles removed and individually vacuum packed. For the first trial, seven fallow deer carcasses were used. Meat from the hind and fore-quarters of each carcass was divided into two equal batches per animal. One batch was minced (through a 5 mm die) and packed into oxygen permeable overwraps and refrigerated at 4°C for a period of eight days under retail display conditions. The second batch was vacuum packed and frozen at -20°C for 2 months at the end of which mince was also produced and monitored over an eight-day period under the same conditions that were used for the fresh mince. Colour, pH, lipid and myoglobin stability was determined. Proximate and fatty acid composition was also determined. No differences (P>0.05) were noted between proximate composition of fresh and frozen/thawed minced meat. The lipid content of fallow deer was 2.4 percent (±0.04). Total n3 fatty acids differed (P<0.05) between treatments and decreased with increased storage and display day. There were significant (P<0.05) treatment and time interactions on all measured colour parameters, TBARS and myoglobin forms. Fresh mince was lighter and had higher redness (a*) and yellowness (b*) values than mince from two months frozen stored meat. Hue angle for fresh mince remained stable throughout display whereas it increased for frozen/thawed mince. Fresh mince had lower TBARS values than frozen/thawed mince. Minced meat produced from frozen/thawed deer meat had higher surface met-myoglobin and total met-myoglobin percentages. Surface and total oxy-myoglobin percentage was higher in fresh mince. The first trial clearly showed colour and lipid stability differences between fresh mince and mince from frozen/thawed meat. It also showed that fresh mince has a longer retail display life than mince produced from frozen/thawed meat (six days and four days, respectively). In the second trial, the effects of frozen storage duration on colour and lipid stability were investigated. Twenty-four fallow deer were used. Twelve were harvested in June (6male 6female) and the other twelve in August (6 male 6female) of the same year.Twenty four hours after harvesting, the fore and hindquarter muscles of the carcasses were deboned, vacuum packed and kept at -20°C until October (i.e. 2months and 4months frozen storage period). Upon thawing, the meat was processed into mince following the same procedure used for the first trialand displayed for a fiveday period under retail display conditions. Frozen duration and gender had no effect (P>0.05) on the proximate composition of fallow deer meat. The total amount of saturated fatty acids (SFA) increased and total amount of poly unsaturated fatty acids (PUFA) decreased as frozen duration and display day increased (P<0.05). Frozen duration affected (P<0.01) lipid oxidation and percentage oxy-myoglobin. Mince pH and all colour parameters (L*, a*, b*,hue and chroma) differed (P<0.05) between treatments on day zero and three. Display day was a significant factor (P<0.05) on all measured parameters. By day three all parameters except pH showed signs of extended oxidation and discolouration as evidenced by reduced redness, decreased colour intensity and high TBARS values. This study showed that prolonged frozen storage negatively affects the colour and lipid stability of meat and increases oxidation of PUFAs during frozen storage. However, the study also suggests that although frozen/thawed meat has a shorter retail display shelf life; the proximate composition of the meat remains unchanged.
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Buzzard, Kathleen Gabriel. "Effects of Different Lowbush Blueberry Purees on Lipid Oxidation in Pre-cooked Ground Turkey Patties." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/BuzzardKG2002.pdf.
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Fernström, Maria. "Effects of endurance exercise on mitochondrial efficiency, uncoupling and lipid oxidation in human skeletal muscle /." Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-059-6/.
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Fortier, Chanel. "Preparation, Characterization, And Application of Liposomes in the Study of Lipid Oxidation Targeting Hydroxyl Radicals." ScholarWorks@UNO, 2008. http://scholarworks.uno.edu/td/889.
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In the onset of many chronic illnesses including Parkinson’s, Alzheimer’s, and cardiovascular diseases, there is evidence to support the delicate balance between prooxidant and antioxidant species is shifted in favor of the former. Under these conditions, many reactive oxygen species (ROS) including hydroxyl radicals, are generated. Hydroxyl radicals formed in close proximity to DNA, nucleotides, proteins, and lipids rapidly oxidize these biological molecules in a nonspecific way. However, their toxicity is limited by their short lifetimes. Currently, the mechanism by which hydroxyl radicals are involved in the onset of many illnesses, particularly with regard to lipid peroxidation, has yielded some controversy in the literature. Conventional studies which generate hydroxyl radicals with Fenton chemistry through bolus additions of iron and hydrogen peroxide do not mimic conditions found physiologically because there is a steady-state concentration of hydrogen peroxide concentration found in normal cellular systems. Also, former reports that used fluorescent fatty acids or free probes intercalated within liposomal membranes did not have the probes covalently attached to the phospholipids making up the liposomes. Thus, the actual placement of the probes over the analysis time may vary with experimental conditions. The objective of this research project was to prepare, characterize, and employ liposomes as models for cell membranes during free radical oxidation. Also, compared to the popularly-used technique of electron spin resonance, (ESR), our aim was to use a fluorescence-based approach which yielded the advantages of high sensitivity, fast analysis time, and less expensive equipment requirements. Degradation of fluorescently-tagged liposomes with probes covalently bound to the phospholipids was correlated with the ability of hydroxyl radicals and other possible reactive oxygen species to penetrate into the liposomes to deeper into the lipophilic layer. However, alone this experimental setup may not fully define the mechanistic role of hydroxyl radicals in lipid oxidation. Thus, a complementary approach embracing the use of MALDI-TOF mass spectrometry, lipophilic scavenger studies, and the effects of cholesterol and temperature allow a deeper understanding of the radically-driven oxidation of lipids. It was determined that hydroxyl radicals were generated and reacted with three fluorescent probes.