Dissertations / Theses: 'Triacylglycerols'

1

Liu, Qintao. "Conversion of triacylglycerols into monoacylglycerols by penicillium roquefortii." Thesis, Sheffield Hallam University, 1998. http://shura.shu.ac.uk/3098/.

Full text

Abstract:

The synthesis and use of monoacylglycerols in food systems havc been reviewed. The use of monoacylglycerols alone or in combination with free fatty acids as food preservatives has been discussed. Model systems have been devised to produce monoacylglycerols (MAGs) from butter and Shea oils with two strains of Penicillium roquefortii, FRR 2456 (isolated from a spoilt melon) and Wisbey PJ (a commercial dairy strain) A semi-micro method was developed using Preparative Thin Layer Chromatography (PTLC) and Gas Chromatography - Mass Spectrometry (GC-MS) of the MAG trimethylsilyl ether derivatives to determine the identification, fatty acid composition and structural isomers of the individual MAG. The main monoacylglycerols produced by spores and emerging mycelium were 1(3)-monoacylsn-lycerols (in suspension culture). Monopalmitin was the major MAG from butter and Shea oils. Monoacylglycerols produced by fungal mycelium (in solid-state culture) were mainly the 1 (3 )-monoacyl-sn-glycerols although approximately 30% were present as 2-monoacyl-snglycerols. Again the main MAG was monopalmitin. It suggested that P. roquefortii produced two lipases, one during germination with specificity to the sn-2 position in the original triacylglycerols (TAGs) and one L3-specific during growth of the fungal mycelium. In addition, flavour compounds, methyl ketones and y-lactones, were found in solid-state culture. The composition of the MAGs formed by lipolysis using a commercial lipase (E.C.3.1.1.3) with 1,3- specificity gave the expected 2-isomers when butter oil was the substrate but gave 1 (3)monostearin rather than the expected 2-monoolein when Shea oil was the substrate. It suggested that acyl migration occurred due to the reactive nature of the original oleate group at the sn-2 position in the Shea oil TAGs. There were no significant differences with fungal strain or temperature of incubation (10 °C and 25°C) on the composition of the MAGs. The mechanism of formation of MAGs from butter and Shea oils has been discussed. It has been suggested that l(3)-MAGs together with free fatty acids may be part of a natural antimicrobial system in high pH foods such as blue mould-ripened cheese where growth of foodborne pathogens such as Listeria monoGytogcnes can be a problem from time to time

APA, Harvard, Vancouver, ISO, and other styles

2

Griffiths, David John. "The synthesis and physical properties of selected triacylglycerols." Thesis, University of St Andrews, 1985. http://hdl.handle.net/10023/14171.

Full text

Abstract:

The study of triacylglycerol interactions in the solid phase and their behaviour during crystallisation requires the availability of individual triacylglycerols of proven positional and structural purity. The aim of this work was to prepare some specific triacylglycerols and to examine their crystallisation behaviour as individual samples and in binary mixtures with each other. The first part of this thesis details the synthesis of glycerol 1-stearate 2-caprate 3-palmitate, glycerol 1-stearate 2-oleate 3-palmitate, glycerol 1-stearate 2-elaidate 3-palmitate, glycerol 1-stearate 2,3-dimyristate and glycerol 1,3-dipalmitate 2-laurate. The unsaturated acids used were isolated from olive oil and modified where required. Methods of analysis for quantitative purity determination are given. The second part of the thesis involves the examination of the selected triacylglycerols by methods of X-ray powder diffraction and differential scanning calorimetry. The triacylglycerols prepared as described were supplemented by lipid samples from other sources [glycerol 1-stearate 2-laurate 3-myristate, glycerol 1-stearate 2-myristate 3-laurate, glycerol 1-palmitate 2-stearate 3-oleate, glycerol 1-palmitate 2,3-dielaidate, glycerol 1,2,3-triarachidate, glycerol 1,2,3-triplamitate, glycerol 1, 2,3-tristearate and cocoa butter]. The polymorphic forms of samples prepared from solvent and from thermal conditioning were obtained. Five pairs of the triacylglycerols were chosen for examination as binary mixtures. The preparation methods and result detailed and summarised in temperature vs. composition (phase) diagrams.

APA, Harvard, Vancouver, ISO, and other styles

3

Hishamuddin, Elina. "Partitioning of triacylglycerols in the fractional crystallisation of palm oil." Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/14091.

Full text

Abstract:

Palm oil is industrially fractionated on a large scale to yield a liquid olein (OL) product composed primarily of low melting triacylglycerols (TAGs) and a solid stearin (ST) product primarily of high melting TAGs. The physical and chemical properties of these fractionated products differ greatly from the original oil, and have added value. The aim of the work presented in this thesis is to study the partitioning of TAGs during the fractional crystallisation of palm oil and how this relates to their theoretical thermodynamic driving forces for crystallisation. Palm oil was studied under isothermal, non-isothermal and postcrystallisation stepwise remelting conditions. Filtered OL and ST products from the experiments were analysed for their TAG compositions by High Performance Liquid Chromatography (HPLC). Raw composition results showed fully saturated TAGs partitioning significantly to the ST phase, but little difference was observed in the compositions of the more unsaturated TAGs between the OL and ST (it would be expected that these would naturally concentrate in the OL). These observations are attributed to high levels of entrained liquid in the filter retentate, which has also been previously reported in the literature. A correction method based on the assumption that no triunsaturated TAGs should be able to crystallise to any significant extent was proposed to recalculate "true" ST compositions. These calculations indicated very high levels of entrainment (with the retentate possessing more liquid than solid), with typically only about 10% of palm oil TAGs crystallising despite forming a thick slurry. Although this assumption has not been directly verified, the corrected compositions showed behaviour that was very consistent with that which would be expected from thermodynamic driving force considerations. In the isothermal and non-isothermal studies conducted, the corrected ST composition revealed that PPP and other saturated TAGs showed the fastest transformation into the ST phase, followed by POP and other monounsaturated TAGs which predominated only once the saturated TAGs had been depleted from the OL phase. Slightly higher concentrations of PPP were achieved at higher isothermal temperatures (in isothermal studies) and lower cooling rates (in non-isothermal studies). Remelting studies on palm oil revealed that the melting process was largely dominated by trisaturated TAGs. This work has also demonstrated that the Focused Beam Reflectance Measurement (FBRM) technique was capable of detecting particle size and population numbers within the crystallising palm oil system and is a useful probe for detecting multiple events occuring in the crystalliser such as nucleation, melting, agglomeration and deagglomeration.

APA, Harvard, Vancouver, ISO, and other styles

4

Lacey, Dominic Jamie. "Synthesis of triacylglycerols in developing seeds of Brassica napus L." Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338217.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Bayés-García, Laura. "Polymorphism and Solid State Miscibility of Triacylglycerols. Application to Food Authentication." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/129313.

Full text

Abstract:

Esta tesis se basa fundamentalmente en el estudio in situ del polimorfismo de triacilgliceroles (TAGs) mayoritarios de aceites y grasas alimentarios, la determinación del comportamiento de fases de algunas de sus mezclas binarias, y la aplicación del polimorfismo como herramienta para la autentificación de productos alimentarios. Se ha llevado a cabo la caracterización polimórfica de los TAGs POP, OPO, POO, POL, SOO, OOO y OOL, básicamente utilizando una combinación de calorimetría diferencial de barrido y difracción de rayos X con radiación sincrotrón (SAXD y WAXD). Así, se han podido monitorizar los procesos dinámicos de cristalización y las transiciones polimórficas cuando las muestras se sometían a diferentes velocidades de enfriamiento y calentamiento. Los resultados obtenidos son directamente aplicables a procesos de cristalización de aceites y grasas alimentarios, con la finalidad de obtener las propiedades deseadas del producto final, utilizando los tratamientos térmicos más eficientes. Para comprender las interacciones intermoleculares que tienen lugar entre TAGs, se ha determinado los diagramas de fases de las mezclas PPO-OPO, PPO-POO y POO-OPO. Se ha observado un comportamiento eutéctico para el sistema PPO-OPO, mientras que en los sistemas PPO-POO y POO-OPO se formaba un compuesto molecular (co-cristal) metaestable, que tendía a separarse en los componentes de origen. Mediante el uso de difracción de rayos X con micro-haz de radiación sincrotrón, se han analizado las microestructuras heterogenias de mezclas de POP-OPO. El estudio de estos agregados cristalinos esferulíticos es directamente aplicable a procesos de fraccionamiento del aceite de palma. Con la finalidad de comprender muestras grasas más complejas, se ha caracterizado el complejo comportamiento polimórfico de mezclas multi-componente de 3 a 6 TAGs. Para el caso particular del aceite de oliva, el comportamiento polimórfico viene básicamente determinado por los TAGs mayoritarios, mientras que los componentes minoritarios parecen desarrollar un papel menos crucial. Finalmente, se ha aplicado el comportamiento polimórfico como herramienta para la autentificación y detección de fraudes en productos alimentarios. Ha sido posible determinar adiciones fraudulentas de aceite de avellana en aceite de oliva virgen extra en concentraciones inferiores al 5%, y se han podido establecer diferencias muy significativas en grasas de jamones Ibéricos de las categorías cebo y bellota.
Lipids, together with proteins and carbohydrates are major nutrients and also employed as lipophilic materials in food, cosmetic and pharmaceutical industries. Alimentary and industrial fats and oils (such as vegetable oils, margarine, chocolate, and confectionery fats) mainly consist of triacylglycerols (TAGs), whose molecules involve different types of fatty acid moieties. TAGs show a complicated crystallization behavior. The physicochemical properties of a TAG molecule are determined by the nature and compositions of the three fatty acid moieties. These properties must be studied not only in their pure systems but also in mixed systems. In particular, studies on binary mixture systems provide valuable information about molecular interactions among different lipid materials. This PhD thesis is based on the study of the in situ polymorphic characterization of the main TAGs of some vegetable and animal fats and oils, some of their mixtures and the use of the polymorphic behavior of edible fats and oils as a tool to determine their authentication. The polymorphic study of the triacylglycerols POP, OPO, POO, POL, SOO, OOO and OOL was in situ characterized by mainly using differential scanning calorimetry (DSC) and synchrotron radiation X-ray diffraction (SR-XRD) with SAXD and WAXD simultaneous measurement. The combined usage of DSC and SR-XRD or laboratory-scale X-ray diffraction enabled us to monitor the occurrence and transformation behavior at different rates of cooling and heating. The results obtained are closely related to actual crystallization processes of edible fats and oils, in which most functional polymorphic forms can be obtained by applying the most efficient thermal treatments. We also determined the phase behavior of binary mixtures of mixed-acid TAGs containing palmitic and oleic fatty acids (i.e. PPO-OPO, PPO-POO and POO-OPO). PPO-OPO system revealed an eutectic behavior, whereas PPO-POO and POO-OPO were molecular compound-forming. Long incubation periods were needed in order to thermodynamically stabilize the binary mixtures, and the results demonstrated that molecular compounds of PPO-POO and POO-OPO were metastable and tended to separate into the pure TAG components. On the other hand, microstructures of spherulites of POP-OPO binary mixtures were analyzed in neat liquid and solution (n-dodecane) systems by using synchrotron radiation microbeam X-ray diffraction (SR-mu-XRD). Due to a molecular compound formation at the 50:50 concentration ratio, 75POP:25OPO and 25POP:75OPO compositions were characterized to study how the microstructures of spherulites of the TAGs mixtures are determined when the molecular compound crystals and POP or OPO component crystals can be formed competitively. Studies of these heterogeneous microstructures in neat liquid and solution are applicable to palm oil fractionation processes by dry and solvent methods. In an attempt to make an approach to complex natural fatty samples, such as olive oil, the polymorphism of multicomponent mixtures (from 3 to 6 TAG components) was analyzed and discussed. Thus, we observed that the polymorphic behavior of an extra virgin olive oil from the Arbequina olive variety was mainly influenced by its main TAGs, whereas apparently minor components did not develop a crucial role. Furthermore, we also used the polymorphic behavior of natural fat and oils (virgin and extra virgin olive oil, and Iberian ham fat) as a tool to determine authenticity (different ham categories depending on the fattening system used) and detection of adulterations (fraudulent additions of hazelnut oil in olive oil). The combined use of DSC and preliminary chemometric calculations permitted determining fraudulent additions of raw hazelnut oil in an extra virgin olive oil (Arbequina) at concentrations below 5%. On the other hand, highly significant differences were detected in the polymorphic behavior of Iberian ham fat from the bellota and cebo categories.

APA, Harvard, Vancouver, ISO, and other styles

6

Dudd, Stephanie Noelle. "Molecular and isotopic characterisation of animal fats in archaeological pottery." Thesis, University of Bristol, 1999. http://hdl.handle.net/1983/2253912b-90e0-4d49-b045-959a53719dc8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Dziubajlo, Maria. "Factors affecting the composition and physical properties of pig adipose tissue triacylglycerols." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46754.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Acheampong, Akwasi. "Development of lc-ms method to identify triacylglycerols in resinous seed oils." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112083.

Full text

Abstract:

Cette thèse a consisté à développer une nouvelle stratégie analytique en utilisant le couplage chromatographie liquide - spectrométrie de masse (LC-MSn) afin d’identifier dans les huiles et corps gras, les triglycérides (TAGs) et leur régio-spécificité. Cette méthodologie analytique générale a été appliquée à 8 huiles de graine de résineux en particulier, à l’huile de pignon de Pinus Koraiensis car ses TAGs sont constitués d’acides gras, possédant une double liaison en position Δ5, non-méthylène alternée, susceptibles de jouer un rôle anti-cholestérol chez l’homme.La thèse se décompose en quatre chapitres: les deux premiers, bibliographiques, traitent respectivement de la taxonomie des 8 résineux étudiés, de la composition en acide gras (AG) de leur graine et des techniques analytiques déjà décrites pour caractériser les TAGs. Le troisième chapitre, expérimental, est dédié au développement de nouvelles stratégies analytiques NARP-LC-MSn mises en place pour identifier les TAGs présents dans les huiles et plus particulièrement à l’huile de pignon de Pinus Koraiensis. Grâce à l’ajout post colonne de sel d’argent, il a été possible de déterminer de manière non ambigüe la structure de tous les TAGs d’un lipide, même ceux présents en faible quantité, par Ag+-NARP-LC-MS mais aussi de déterminer la structure de chaque AG constitutif d’un TAG par fragmentation de l’adduit moléculaire par Ag+-NARP-LC-MS2. Le problème de la distinction des TAGs ayant la même masse moléculaire, les mêmes longueurs de chaine mais des positions de double liaisons différentes, a été résolu en développant une méthode d’identification des TAGs à partir des lois de rétention chromatographiques qui relient linéairement le logarithme du facteur de rétention de chaque TAG soit au nombre total de carbone soit au nombre total de double liaisons. Cette étude a permis d’identifier 22 nouveaux TAGs parmi un nombre total de 58 TAGs caractérisés. Elle a amené la preuve que le résidu AG saturé à 17 atomes de carbone est ramifié et non linéaire. Elle a mis en évidence la présence de trois AGs constitutifs qui n’ont jamais été décrit: 19:1, 19:2 et 24:0 dans l’huile de pignon de Pinus Koraiensis. Le quatrième chapitre porte sur le développement de trois méthodes de détermination de la régiospécificité des TAGs, grâce à la seule SM: (1) une méthode Ag+-NARP-LC-ESI-MS2 utilisant les rapports des ions diglycériques des TAGs. Il en ressort que cette méthode n’est pas assez fiable pour déterminer la structure des TAGs. (2) la seconde méthode fait appel à des expériences MS4/ MS5 sur les adduits argent des TAGs. Elle s’avère pertinente à condition d’avoir à disposition les couples de TAGs standards. (3) enfin une troisième méthode, utilisant la MS2, s’appuie sur le principe de la méthode de dissociation compétitive d’une paire [TAGref – Li -TAG]+. En utilisant la méthode des ajouts dosés il est montré qu’elle ne nécessite que de la disponibilité d’un seul des deux TAGs stéréoisomères comme standard.Ces méthodes originales ont permis, malgré leurs limites respectives de caractériser la régiospécificité d’un certain nombre de TAGs présents dans l’huile de graine de Pinus Koraiensis
This thesis consisted of developing a new analytical strategy using liquid chromatography coupled with mass spectrometry (LC-MSn) to identify in oils and fats, triglycerides (TAGs) and their regio-specificity. The general analytical methodology was applied to 8 conifers seed oils, in particular, the seed oil of Pinus koraiensis. These conifer seed oils differ from common edible vegetable oils by having a series of unusual polyunsaturated fatty acids (UPIFA) with a polymethylene-interrupted (PMI) double bond system and a double bond at the 5 position which may have anti-cholesterol properties. This thesis is composed of four chapters: the two first chapters, literature review, are devoted respectively to TAGs of the 8 resinous seed oils studied and analytical techniques already used. The third chapter is dedicated to the development of a new analytical strategy combining HPLC with mass spectrometry method to identify TAGs in Pinus Koraiensis seed oil. Thanks to post column addition of silver salt, it was possible to determine the TAGs present by Ag+-NARP-LC-MS and also the fatty acids composition of the TAGs by Ag+-NARP-LC-MS2. Concerning the distinction between TAGs with the same mass, same chain length but differing positions of double bond on fatty acid chain, it was determined by chromatographic retention rules which link linearly the logarithm of retention factor of each TAG to the total carbon number or the total number of double bonds. This study has identified 22 new TAGs from a total of 58 TAGs characterized. It confirmed the knowledge that the saturated fatty acid with 17 carbon atoms is branched, not linear. It highlighted the presence of three constituent fatty acids that have never been described: 19:1, 19:2 and 24:0 in the seed oil of Pinus koraiensis. The last experimental part is devoted to the regiospecificity determination of TAGs. Three methodologies were developed. The first one used the ratios of diacylglycerol ions of TAGs but was not reliable enough. The second method used the LC-MS4 experiments (It is relevant if they have available couples of TAG standards). Finally, a third method, using MS2, based on the principle of the method of competitive dissociation of a pair [TAGref - Li-TAG] +. Using the method of standard additions it has been shown that it requires the availability of one of the two stereoisomers TAGs as a standard.These methods provide a significantly different approach to regioisomer characterization of TAGs and overcome most of the shortcomings of existing methodologies

APA, Harvard, Vancouver, ISO, and other styles

9

Lopez, Christelle. "Contribution à l'étude de la cristallisation des triacylglycerols : application aux émulsions laitières." Paris 6, 2001. http://www.theses.fr/2001PA066453.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Filippou, Androulla. "The acute and chronic effects of palmitic acid-rich triacylglycerols on cardiovascular risk." Thesis, King's College London (University of London), 2012. https://kclpure.kcl.ac.uk/portal/en/theses/the-acute-and-chronic-effects-of-palmitic-acidrich-triacylglycerols-on-cardiovascular-risk(34c8ae7a-5aea-47df-88a4-0c77a566db15).html.

Full text

Abstract:

The thesis investigated the hypothesis that differences in the triacylglycerol structure of palmitic acid-rich fats influence lipid metabolism and glucose/insulin homeostasis. A review of the literature and acute test meal and chronic feeding studies were conducted in human subjects. Postprandial changes in plasma lipids, apolipoprotein-B48, glucose, C-peptide, insulin, and glucose dependent insulinotropic polypeptide (GIP) were compared in healthy men (n=25) and women (n=25) following meals providing 50g fat as high-oleic sunflower oil (HOS; control), palm olein (PO), interesterified palm olein (IPO), and lard (0.6, 9.2, 39.1, and 70.5 mol% 16:0 respectively at sn-2) using a randomized crossover design. The sn-2-rich meals elicited lower triacylglycerol concentrations up to 3 h and a lower incremental area under the curve after lard vs. HOS and PO meals. GIP concentrations were lower following the lard and IPO meals vs. HOS and IPO but there were no significant changes in insulin, C-peptide and glucose. The effects of consuming PO (control) vs. IPO vs. HOS on insulin release (measured as increases in C-peptide in response to a test meal) were investigated in healthy Malaysian men (n=10) and women (n=31). Test fats (45g/d) were incorporated into daily meals, and following a 2-week run-in period on the PO diet (30% energy fat; 20% energy PO), participants were randomly allocated to the PO or IPO or HOS diets for three consecutive 6-week periods. No differences between diets in C-peptide secretion, insulin sensitivity or postprandial glucose were observed. The HOS diet lowered total- and LDL-cholesterol, and apolipoprotein-B100 compared with the IPO and PO diets. The work described does not support the assertion that palmitic acid in the sn-2 position has adverse effects on lipid metabolism or glucose/insulin homeostasis compared to that in the sn-1 and sn-3 position. The implications of these findings are discussed in relation to the food industry.

APA, Harvard, Vancouver, ISO, and other styles

11

Gallart, Sirvent Pau. "Non-edible triacylglycerols as feedstock to prepare phase change materials and pressure-sensitive adhesives." Doctoral thesis, Universitat de Lleida, 2017. http://hdl.handle.net/10803/405959.

Full text

Abstract:

Aquest programa de recerca està enfocat en l'aprofitament de triacilglicèrids vegetals i animals d'origen no comestible per preparar productes de valor afegit. Els triacilglicèrids són una font excel•lent per substituir el petroli ja que provenen de diferents fonts renovables i tenen propietats químiques i físiques interessants. No obstant, tot i que són renovables, el seu ús s’ha de discutir. D'una banda, a causa del origen dels triglicèrids, ja que els comestibles competeixen directament amb l'alimentació. Per tant, s'han fet servir dues fonts diferents com són el greix animal no comestible dels escorxadors municipals i un oli vegetal no comestible provinent d'un arbre de cultiu Xinès (Vernicia fordii) anomenat oli de tung. D’altra banda, part de la química involucrada en la preparació de productes "bio-based" té efectes negatius per al medi ambient ja que genera grans quantitats de residus i normalment es fan servir altes temperatures i reactius perillosos. Per superar aquest problema, aquest treball aprofita les condicions suaus i la reusabilitat dels biocatalitzadors com les lipases imobilitzades i les "resting cells". A més, van ser una prioritat els reactius químics no perillosos, les practiques generadores de pocs residus i els reactius barats per tal de completar la transformació del greix animal no comestible i l'oli de tung.
Este programa de investigación está enfocado en el aprovechamiento de triacilgliceridos vegetales y animales de origen no comestible para preparar productos con valor añadido. Los triacilgliceridos son una fuente excelente para substituir el petróleo ya que provienen de distintas fuentes renovables y tienen propiedades químicas y físicas interesantes. No obstante, aunque son renovables, su uso tiene que discutirse. Por un lado, debido al origen de los trigliceridos, ya que los comestibles compiten directamente con la alimentación. Por lo tanto, se han usado dos fuentes distintas como son la grasa animal no comestible de los mataderos municipales y un aceite vegetal no comestible proveniente de un árbol de cultivo Chino (Vernicia fordii) llamado aceite de tung. Por el otro lado, parte de la química involucrada en la preparación de productos “bio-based” tiene efectos negativos para el medio ambiente ya que genera grandes cantidades de residuos y normalmente se usan altas temperaturas y reactivos peligrosos. Para superar este problema, este trabajo aprovecha las condiciones suaves y la reusabilidad de los biocatalizadores como las lipasas inmovilizadas y las “resting cells”. Además, fueron una prioridad los reactivos químicos no peligrosos, practicas generadoras de pocos residuos y reactivos baratos para completar la transformación de la grasa animal no comestible y el aceite de tung.
The research described in this document is focused on the utilization of vegetable and animal non-edible triacylglycerols to prepare value added products. Triacylglycerols appeared to be an excellent source to substitute petroleum since they come from distinct renewable sources and have various interesting chemical and physical properties. Nevertheless, although they are renewable, their utilization as starting materials to produce chemicals can cause some concerns. On the one hand, edible triacylglycerols compete directly with food and feed. To overpass these concerns, two distinct sources of non-edible triacylglycerols were used such as non-edible animal fat from slaughterhouses and vegetable oil from a Chinese three crop (Vernicia fordii) known as tung oil. On the other hand, some of the chemistal procedures involved in the preparation of bio-based products have negative effects on the environment since high amount of wastes are generated and high temperatures and hazardous reagents are commonly employed. To overcome these issues, the present work takes advantage of the milder conditions and reusability of biocatalyst such as immobilized lipases and resting cells. Additionally, non-hazardous chemicals, low generating waste practices and cheap reagents were a priority to complete the transformation of non-edible animal fat and tung oil.

APA, Harvard, Vancouver, ISO, and other styles

12

Lam, Chi-chung, and 林子聰. "Nuclear magnetic resonance spectroscopy as an analytical tool in the structural analysis of triacylglycerols." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31233636.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Miller, Neidi. "Process design and modeling for the production of triacylglycerols (TAGs) in Rhodococcus opacus PD630." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70461.

Full text

Abstract:

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2012.
"February 2012." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 32-34).
The oleaginous microorganism Rhodococcus opacus PD630 was used to study the characteristics and kinetics of the accumulation of triacylglycerols (TAGs) in cells. In this process, accumulation of TAG is stimulated when a carbon source is present in the medium in excess and the nitrogen source is limiting growth. Under controlled fermentation conditions the organism Rhodococcus opacus PD630 has been shown to grow to high cell density, producing high yields of TAGs (above 50% of cell dry weight) in a relatively short period of time. In this study, the reaction stoichiometry was established and the carbon balance for the process has been effectively closed, accounting for approximately 91% of the total carbon in the system. Several fed-batch strategies were explored at the IL benchtop bioreactor scale. Feeding both carbon and ammonium sulfate as the nitrogen source can sustain cell growth but was found to significantly obstruct the accumulation of TAGs. While these fed-batch strategies did not lead to titer improvements, they did highlight the significance of TAG degradation for growth. To aid in future process design strategy optimization an unstructured kinetic model was developed to describe the dynamics of the fermentation of Rhodococcus opacus PD630 and its triacylglycerol (TAG) production. The kinetic parameters for this model were either measured from experimental data or estimated by fitting the experimental data using least-squares non-linear regression. Global minimum of the sum of squared errors (SSE) between the model prediction and various experimental data sets was found by an iterative process of parameter space exploration. The minimum SSE obtained was 91.229. The proposed model is the first step towards understanding and optimizing the process of lipid production and accumulation in oleaginous organisms.
by Neidi Miller.
S.M.

APA, Harvard, Vancouver, ISO, and other styles

14

Lam, Chi-chung. "Nuclear magnetic resonance spectroscopy as an analytical tool in the structural analysis of triacylglycerols /." [Hong Kong : University of Hong Kong], 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13787056.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

鄭家樑 and Ka-leung Cheng. "A study of the 13C-NMR properties of some fatty acid derivatives and their triacylglycerols." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31212931.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Cheng, Ka-leung. "A study of the 13C-NMR properties of some fatty acid derivatives and their triacylglycerols /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B17537307.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Mottram, Hazel Rosemary. "The application of HPLC-APCI MS to the regiospecific analysis of triacylglycerols in edible oils and fats." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285582.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Swaim, Zachary Taylor. "Lipid metabolism by right whales using fecal samples to assess assimilation of copepod triacylglycerols and wax esters /." View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-1/swaimz/zacharyswaim.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Hmida, Dorra. "Recherche de conditions alternatives à l’utilisation de solvants chlorés en Chromatographie Liquide Non-Aqueuse à Polarité Inversée de Phases. Application à l’analyse des lipides présents dans les milieux complexes." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS189/document.

Full text

Abstract:

Déterminer la composition en triacylglycérols des huiles végétales est un défi important à relever aussi bien en biologie végétale que dans le domaine médical ou celui de l’industrie agro-alimentaire. La chromatographie en phase liquide à polarité inversée de phases en milieu non aqueux (NARP-LC) est la méthode la plus utilisée, avec cependant une utilisation récurrente de solvants chlorés. Le premier objectif de ce travail a été de proposer des conditions analytiques alternatives n’utilisant pas de solvants chlorés. Pour ce faire, nous avons établi le diagramme de force éluante sur phases stationnaires en C18 des phases mobiles binaires constituées d’acétonitrile comme solvant faible et de divers solvants forts (acétone, iso-propanol, acétate d’éthyle, butanol) à quatre températures différentes (25, 43, 63 et 85°C). La comparaison dans des conditions iso-éluantes de l’analyse de 9 huiles de graines contenant une large gamme de TAG nous a permis de montrer que le mélange MeCN/BuOH 74/26 à 25°C est le meilleur choix, en terme de sélectivité pour l’analyse des TAG. Ce qui répond à notre premier objectif. Dans un second temps, nous avons comparé le potentiel séparatif des phases stationnaires de nouvelle génération à petit diamètre de particules, partiellement ou totalement poreuses. L’optimisation des conditions chromatographiques nous a permis de décrire deux systèmes chromatographiques, très performants, en termes d’efficacité et de rapidité. Le premier permet la séparation de TAG contenant des acides gras polyinsaturés isomères de position en C18 : 3 et C18 : 2. L’identification de ces isomères particuliers a été réalisée grâce à la synthèse d’informations complémentaires, obtenues en GC/MS, LC/MS ainsi que l’utilisation de lois de rétention chromatographiques. En outre, ce travail nous a permis de proposer un tableau récapitulatif regroupant un très grand nombre de TAG, qui n’ont jamais été décrits à notre connaissance. Le second permet une analyse rapide de l’huile d’olive, en moins de 5 min, tout en respectant les consignes qualitatives imposées par l’organisme «Conseil Oléique International (COI)». Comparée aux méthodes officielles couramment utilisées, elle mérite d’être proposée comme méthode de référence pour le contrôle de qualité de l’appellation de ces huiles
The determination of triacylglycerols in vegetable oils is an important challenge in plant biology, in the medical field, and in food industry. Nowadays, non-Aqueous Reversed Phase Liquid Chromatography (NARP-LC) using chlorinated solvents is commonly used for this purpose. The first objective of this work was to develop alternative analytical conditions that can avoid using chlorinated solvents. In a first step, by using C18 stationary phases, we have established the eluotropic solvent strength scale as a function of temperature of several binary mobile phases consisting of acetonitrile as weak solvent and various strong solvents including acetone, isopropanol, ethyl acetate, and butanol. The comparison of the results obtained under iso-eluotropic conditions for nine seed oils containing a wide range of TAG enabled us to show that the MeCN/BuOH (74/26, v/V) mixture operating at 25 °C are the best mobile phase conditions for TAG analysis, in terms of selectivity, thus avoiding the use of chlorinated solvents. In a second step, we compared the separation of TAGs on new generation of fully or partially porous stationary phase particles of small diameter. After optimizing the separating conditions, the obtained data allowed us to propose two highly efficient chromatographic systems. The first system enables the efficient separation of C18:3 and C18:2 positional isomers of C18 polyunsaturated fatty acids containing TAG. For the identification of these TAG isomers, it was necessary to combine the data obtained by GC-MS and LC -MS as well as the data obtained by the application of some chromatographic retention laws. Taken together, these results allowed us to provide a list containing a large number of TAG unknown to date. The second system allows rapid analysis of olive oil in less than 5 min. This system obeying the guidelines of the International Olive Council can be proposed as a candidate reference method for rapid quality control of olive oils

APA, Harvard, Vancouver, ISO, and other styles

20

Coffill, Cynthia Rose. "The effects of di- and triacylglycerols on the charge, stability and conformation of HDL and on hepatic lipase activity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq36675.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Buck, Vinodini. "Rheological Properties of Peanut Paste and Characterization of Fat Bloom Formation in Peanut-Chocolate Confectionery." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/26881.

Full text

Abstract:

Fat bloom in chocolates is the gray-white discoloration and dullness that can occur on the surface of the confectionery. Fat bloom is a common quality defect that can result from temperature fluctuations during storage. Chocolates candies with peanuts or other nut fillings are more prone to fat bloom compared to plain chocolates, due to a release of incompatible nut oils into the chocolate matrix. The overall goal of this study was to determine if differences in triacylglycerol (TAG) composition and rheological properties of high, medium, and normal oleic peanuts influence fat bloom formation. All three peanut varieties showed high concentrations of triolein. Normal oleic peanuts had a slightly higher trilinolein than high and medium oleic peanuts, which contained trilinolein in trace amounts. Peanut pastes from the three peanut varieties all had a minimum apparent yield stress, and all pastes showed varying degrees of shear thinning. The apparent yield stress of high and normal oleic pastes was higher than the apparent yield stress of medium oleic paste. The absolute value of the flow index behavior was 1 for the high oleic peanut paste, suggesting friction in the experimental apparatus, even with use of Teflon plates. The peanut chocolate candies took around 45 days for significant dulling of the chocolates with temperature cycling between 26-29 Â°C approximately every 26 hours. Optical microscopy scans showed differences in glossiness and surface textural attributes of the unbloomed and bloomed peanut chocolate confectionery. Consumer evaluation showed some differences in the glossiness and significant differences in surface texture of unbloomed and bloomed chocolates. A majority (62%) of the survey respondents had seen whitish discoloration in chocolates and 40% of the respondents thought this is because the chocolate had grown old.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

22

Newman, Ronald Edward. "Modulation of avian metabolism by dietary fatty acids." Thesis, The University of Sydney, 2000. http://hdl.handle.net/2123/799.

Full text

Abstract:

The role of dietary fatty acids and their subsequent effects on metabolism has received considerable attention in mammalian species. It is becoming increasingly clear that fatty acids have metabolic roles over and above their influence on energy density of the diet. Recent studies have linked changes in the fatty acyl composition of the plasma membrane, induced by the dietary fat profile, to alterations in both lipid and glucose metabolism. These dietary induced changes have profound effects on insulin action, glucose transport and enzyme activity that regulate triglyceride and fatty acid synthesis, factors that ultimately influence protein and lipid deposition of animals. Because of their high growth rate, broiler chickens have a high requirement for energy and the use of triglycerides as a major energy source has resulted in a fat carcass. A change in the glucose-insulin balance has been suggested as being the main reason for differences in adiposity between broilers selected for fatness or leanness. The hypotheses of this thesis is based on the finding that dietary polyunsaturated fatty acids (PUFA's) increase the sensitivity of muscle tissue to insulin and this would presumably augment insulin-stimulated glucose uptake into muscle cells. Therefore, increasing the capacity of broiler muscle tissue to utilise glucose as its principal energy substrate would reduce the bird's reliance on triglycerides and this inturn would result in a leaner carcass. The aims of this study are firstly to explore the role that dietary PUFA's from the n-3 and n-6 series have on the growth and body composition of broiler chickens and secondly to determine the relationships between dietary fatty acid profile, tissue insulin sensitivity and lipid deposition. Because dietary fatty acids have been implicated in the modulation of hormones important for the growth and development of animals, a third aim of this thesis is to determine the effects of dietary n-3 and n-6 polyunsaturated fatty acids on pituitary and adrenal sensitivity. Since the modulation of metabolism by dietary fatty acids has been attributed to changes in the fatty acyl composition of the plasma membrane, the final aim of this study will be to investigate and characterise the molecular species of the breast muscle choline and ethanolamine phospholipids. Feeding either fish oil a source of n-3 PUFA's or sunflower oil a source of n-6 PUFA's fatty acids to broiler chickens resulted in a significant (P<0.01) reduction in the abdominal fat pad mass and a modest increase in breast muscle mass when compared to broilers fed edible tallow. Associated with the changes in carcass composition was an alteration in energy substrate utilisation. This was reflected by lower respiratory quotients and reduced triglyceride and insulin concentrations for the chickens fed the two PUFA diets. Coupled to the shift in energy metabolism was a significant (P<0.05) increase in the proportion of PUFA's incorporated into the abdominal fat pad and breast muscle. The dietary fat supplements resulted in the incorporation of specific fatty acid subtypes. Feeding fish oil significantly increased the proportion of long-chain n-3 PUFA's whereas feeding sunflower oil significantly increased the proportion of long-chain n-6 PUFA's compared to tallow feeding whose tissues were dominated by a higher proportion of saturated fatty acids. It was further shown that dietary n-3 and n-6 PUFA's enhanced glucose /insulin action. Feeding either fish oil or sunflower oil to broiler chickens increased insulin action when examined by an intravenous glucose tolerance test. The maximal insulin release in response to the glucose infusion was higher in the tallow fed group compared to either the sunflower oil or fish oil groups. To estimate the disappearance rate of glucose from the plasma and its incorporation into tissues, 2-deoxy-D-3H glucose was infused into each chicken. There were no significant differences in the clearance rate of 2-deoxy-D-3H glucose from the plasma. However, when measured under steady state conditions, the labelled glucose incorporation into the breast muscle was greater in birds fed fish oil compared to either tallow or sunflower oil feeding. The dietary fatty acid induced increase in insulin action suggests that the sensitivity of muscle cells to insulin was enhanced. This modulation of tissue sensitivity by dietary fatty acids was also shown to occur at the level of the pituitary. To provide an estimate of pituitary sensitivity, bolus GnRH and GHRH infusions were given on different days to chickens fed the three dietary treatments. Feeding sunflower oil (n-6 PUFA's) increased the level of GH that was released in response to the GHRH infusion when compared to birds fed either tallow or fish oil (n-3 PUFA's). This dietary fatty acid modulation appears to be specific to certain pituitary cell types as there was no effect on LH secretion following the GnRH infusion. Dietary fatty acid modulation of endocrine gland sensitivity is particular to the gland type. Although the dietary treatments mediated a distinct pattern in pituitary sensitivity to GHRH infusion, these same three diets did not influence adrenal sensitivity, as there was no difference in the corticosterone profile following either ACTH or CRF infusion. The previously observed physiological changes for the three dietary groups was expected to be positively correlated to an alteration of the plasma membrane phospholipids induced by the dietary fatty acids. Supplementation with fish oil (n-3 PUFA's) significantly increased levels of both eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) into the choline (PC) and ethanolamine (PE) breast muscle phospholipids compared to either sunflower oil (n-6 PUFA's) or tallow supplementation. The increase in n-3 PUFA incorporation was associated with a corresponding decrease in the proportion of arachidonic acid (AA; 20:4n-6) an event that would presumably alter substrate availability for the 1- and 2-series eicosanoids. However, feeding sunflower oil or tallow gave a molecular species profile that was remarkably similar in both fatty acid subtype and proportion. This suggests that the plasma membrane dynamics would be similar for these two dietary groups. Therefore, it is appears that factors other than a change in the fatty acyl- composition of the plasma membrane may be responsible for modifying the physiology of the broiler.

APA, Harvard, Vancouver, ISO, and other styles

23

Newman, Ronald Edward. "Modulation of avian metabolism by dietary fatty acids." University of Sydney. Veterinary Science, 2000. http://hdl.handle.net/2123/799.

Full text

Abstract:

The role of dietary fatty acids and their subsequent effects on metabolism has received considerable attention in mammalian species. It is becoming increasingly clear that fatty acids have metabolic roles over and above their influence on energy density of the diet. Recent studies have linked changes in the fatty acyl composition of the plasma membrane, induced by the dietary fat profile, to alterations in both lipid and glucose metabolism. These dietary induced changes have profound effects on insulin action, glucose transport and enzyme activity that regulate triglyceride and fatty acid synthesis, factors that ultimately influence protein and lipid deposition of animals. Because of their high growth rate, broiler chickens have a high requirement for energy and the use of triglycerides as a major energy source has resulted in a fat carcass. A change in the glucose-insulin balance has been suggested as being the main reason for differences in adiposity between broilers selected for fatness or leanness. The hypotheses of this thesis is based on the finding that dietary polyunsaturated fatty acids (PUFA�s) increase the sensitivity of muscle tissue to insulin and this would presumably augment insulin-stimulated glucose uptake into muscle cells. Therefore, increasing the capacity of broiler muscle tissue to utilise glucose as its principal energy substrate would reduce the bird�s reliance on triglycerides and this inturn would result in a leaner carcass. The aims of this study are firstly to explore the role that dietary PUFA�s from the n-3 and n-6 series have on the growth and body composition of broiler chickens and secondly to determine the relationships between dietary fatty acid profile, tissue insulin sensitivity and lipid deposition. Because dietary fatty acids have been implicated in the modulation of hormones important for the growth and development of animals, a third aim of this thesis is to determine the effects of dietary n-3 and n-6 polyunsaturated fatty acids on pituitary and adrenal sensitivity. Since the modulation of metabolism by dietary fatty acids has been attributed to changes in the fatty acyl composition of the plasma membrane, the final aim of this study will be to investigate and characterise the molecular species of the breast muscle choline and ethanolamine phospholipids. Feeding either fish oil a source of n-3 PUFA�s or sunflower oil a source of n-6 PUFA�s fatty acids to broiler chickens resulted in a significant (P<0.01) reduction in the abdominal fat pad mass and a modest increase in breast muscle mass when compared to broilers fed edible tallow. Associated with the changes in carcass composition was an alteration in energy substrate utilisation. This was reflected by lower respiratory quotients and reduced triglyceride and insulin concentrations for the chickens fed the two PUFA diets. Coupled to the shift in energy metabolism was a significant (P<0.05) increase in the proportion of PUFA�s incorporated into the abdominal fat pad and breast muscle. The dietary fat supplements resulted in the incorporation of specific fatty acid subtypes. Feeding fish oil significantly increased the proportion of long-chain n-3 PUFA�s whereas feeding sunflower oil significantly increased the proportion of long-chain n-6 PUFA�s compared to tallow feeding whose tissues were dominated by a higher proportion of saturated fatty acids. It was further shown that dietary n-3 and n-6 PUFA�s enhanced glucose /insulin action. Feeding either fish oil or sunflower oil to broiler chickens increased insulin action when examined by an intravenous glucose tolerance test. The maximal insulin release in response to the glucose infusion was higher in the tallow fed group compared to either the sunflower oil or fish oil groups. To estimate the disappearance rate of glucose from the plasma and its incorporation into tissues, 2-deoxy-D-3H glucose was infused into each chicken. There were no significant differences in the clearance rate of 2-deoxy-D-3H glucose from the plasma. However, when measured under steady state conditions, the labelled glucose incorporation into the breast muscle was greater in birds fed fish oil compared to either tallow or sunflower oil feeding. The dietary fatty acid induced increase in insulin action suggests that the sensitivity of muscle cells to insulin was enhanced. This modulation of tissue sensitivity by dietary fatty acids was also shown to occur at the level of the pituitary. To provide an estimate of pituitary sensitivity, bolus GnRH and GHRH infusions were given on different days to chickens fed the three dietary treatments. Feeding sunflower oil (n-6 PUFA�s) increased the level of GH that was released in response to the GHRH infusion when compared to birds fed either tallow or fish oil (n-3 PUFA�s). This dietary fatty acid modulation appears to be specific to certain pituitary cell types as there was no effect on LH secretion following the GnRH infusion. Dietary fatty acid modulation of endocrine gland sensitivity is particular to the gland type. Although the dietary treatments mediated a distinct pattern in pituitary sensitivity to GHRH infusion, these same three diets did not influence adrenal sensitivity, as there was no difference in the corticosterone profile following either ACTH or CRF infusion. The previously observed physiological changes for the three dietary groups was expected to be positively correlated to an alteration of the plasma membrane phospholipids induced by the dietary fatty acids. Supplementation with fish oil (n-3 PUFA�s) significantly increased levels of both eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) into the choline (PC) and ethanolamine (PE) breast muscle phospholipids compared to either sunflower oil (n-6 PUFA�s) or tallow supplementation. The increase in n-3 PUFA incorporation was associated with a corresponding decrease in the proportion of arachidonic acid (AA; 20:4n-6) an event that would presumably alter substrate availability for the 1- and 2-series eicosanoids. However, feeding sunflower oil or tallow gave a molecular species profile that was remarkably similar in both fatty acid subtype and proportion. This suggests that the plasma membrane dynamics would be similar for these two dietary groups. Therefore, it is appears that factors other than a change in the fatty acyl- composition of the plasma membrane may be responsible for modifying the physiology of the broiler.

APA, Harvard, Vancouver, ISO, and other styles

24

Jahaniaval, Firouz. "Effects of proteins and triacylglycerols on the physicochemical and functional properties of a double emulsion system (oil-in-water-in-oil emulsion)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ56283.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Müller, Stephanie [Verfasser], Ágnes [Gutachter] Fekete, Rosalia [Gutachter] Deeken, and Martin J. [Gutachter] Müller. "Plant thermotolerance: The role of heat stress-induced triacylglycerols in Arabidopsis thaliana / Stephanie Müller ; Gutachter: Agnes Fekete, Rosalia Deeken, Martin J. Müller." Würzburg : Universität Würzburg, 2017. http://d-nb.info/1138566659/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Helaine, Dominique. "Cinétique et modélisation de l'action conjuguée de lipases et de penicillium roquefortii dans un procédé de conversion de triacylglycerols en méthyl-cétones." Vandoeuvre-les-Nancy, INPL, 1992. http://www.theses.fr/1992INPL099N.

Full text

Abstract:

L'objectif de ce travail a été de contribuer à l'étude, d'une part, des mécanismes de lipolyse de la matière grasse laitière par différentes lipases, et d'autre part, de la conversion d'un mélange d'acides gras (ag) en méthyle-cétones par une souche de penicillium roquefortii. Dans une première partie, la cinétique d'hydrolyse des ag de 4 à 12 atomes de carbone et la spécificité d'action de 7 lipases différentes, appliquées à une émulsion reversé de matière grasse laitière sont déterminées. Deux groupes de lipases sont identifiés pour lesquels l'hydrolyse de ces ag représente respectivement, 15 et 40% de la totalité des ag libérés. L'étude cinétique de la libération du glycérol permet de caractériser la spécificité d'attaque des lipases. Une modélisation de l'évolution des espèces acylglycérols est proposée. La seconde partie traite de l'étude de l'influence de paramètres de culture et de mise en œuvre du procédé de bioconversion d'acides gras volatils en méthyl-cétones par penicillium roquefortii. L'évolution de la concentration d'acide butyrique joue un rôle clé en inhibant la croissance du champignon et sa capacité à métaboliser les différents substrats précurseurs des methyl-cétones. Enfin, deux approches simples et originales de modélisation, de la libération des ag et de la production de methyl-cétones respectivement, sont présentées et discutées. L'ensemble de ce travail intéresse directement l'industrie laitière, tant pour la fabrication de fromage à pate persillée, que pour la production de concentrés aromatiques de type fromage

APA, Harvard, Vancouver, ISO, and other styles

27

Rabelo, Juliana. "Viscosidade de compostos e misturas graxas : determinação experimental e desenvolvimento de uma metodologia de predição." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/254889.

Full text

Abstract:

Orientador: Antonio Jose de Almeida Meirelles
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-05T02:09:23Z (GMT). No. of bitstreams: 1 Rabelo_Juliana_M.pdf: 2293566 bytes, checksum: 7592ac89859a7882bd6ce62626eb622a (MD5) Previous issue date: 2005
Resumo: Com o objetivo de predizer e descrever a viscosidade de diferentes compostos graxos e suas misturas, este trabalho desenvolveu um procedimento de cálculo baseado em métodos de contribuição de grupos. Um novo modelo para predição da viscosidade de substâncias graxas puras foi desenvolvido, inspirado no modelo proposto por CERIANI e MEIRELLES (2004) para predição da pressão de vapor. O presente trabalho ajustou parâmetros de contribuição de grupos para o modelo proposto, tomando como base dados experimentais de compostos graxos (ácidos graxos, álcoois graxos, ésteres graxos e triacilgliceróis) presentes na literatura. Utilizando o método MARQUARD, o ajuste dos parâmetros envolveu a minimização de uma função objetivo que representava o somatório dos desvios relativos entre os valores experimentais e calculados de viscosidade dinâmica de compostos graxos puros. Tal processo foi realizado através de programas desenvolvidos no SAS ® e de planilhas eletrônicas em EXCEL, nas quais podiam ser feitas análises ponto a ponto dos ajustes. O trabalho envolveu ainda a determinação de um conjunto extenso de dados experimentais de viscosidade de misturas graxas, a caracterização química de óleos vegetais utilizados no teste da capacidade preditiva do modelo e teste dos modelos de estimativa de densidade e de viscosidade de misturas com parâmetros disponíveis na literatura. Confirmada a sua eficiência, este modelo será de interesse para o desenvolvimento de processos e projetos de equipamentos industriais, uma vez que dados de viscosidade de compostos graxos são escassos na literatura
Abstract: This work aims to describe and predict the viscosity of different fatty compounds and their mixtures by developing a predictive model based on the concept of group contribution. A new model developed in this work was based in the method suggested by CERIANI e MEIRELLES (2004) for vapor pressure prediction. All the group parameters have been adjusted based on experimental data for fatty acids, fatty alcohols, fatty esters and triacylglycerols. Using the method of MARQUARD, the adjustment of parameters have minimized an objective function which is based on the sum of the relative deviation between the experimental and calculated values of the dynamic viscosity of fatty compounds. The softwares used for this work was SAS ® and EXCEL. This work has also determined an extensive experimental data bank of viscosities of fatty compounds mixtures. Some models of densities and viscosities found in the literature have been tested. The method suggested in this work can be a valuable tool for the design of industrial equipments of the oil industry, since such experimental data are relatively scarce in the literature
Mestrado
Mestre em Engenharia de Alimentos

APA, Harvard, Vancouver, ISO, and other styles

28

Simas, Rosineide Costa. "Caracterização de óleos vegetais e petróleo por espectrometria de massas em condições ambiente e com alta exatidão e resolução." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248703.

Full text

Abstract:

Orientador: Marcos Nogueira Eberlin
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
Made available in DSpace on 2018-08-17T04:42:07Z (GMT). No. of bitstreams: 1 Simas_RosineideCosta_D.pdf: 5859215 bytes, checksum: bfba079c3f7e2a4ec510da69e7858d40 (MD5) Previous issue date: 2010
Resumo: A caracterização química de óleos de forma rápida, eficiente e com mínimo preparo de amostras é um desafio para a química analítica moderna. Este estudo abrangeu a caracterização química de 15 amostras de óleos vegetais e 6 amostras de petróleo, e demonstrou a versatilidade da técnica de espectrometria de massas (MS) nesta área. A caracterização de óleos vegetais foi feita por uma técnica de ionização ambiente desenvolvida no Brasil, denominada Easy Ambient Sonic-Spray Ionization (EASI) e utilizando como analisador de massas um equipamento monoquadrupolar, que possui resolução unitária. Foi obtido, para os óleos vegetais, a sua composição de triacilglicerídeos (TAG), ácidos graxos livres e hidroperóxidos utilizando apenas uma gota de óleo e nenhum preparo de amostra. A análise direta de óleos vegetais possibilitou ainda propor um método quantitativo por EASI-MS para determinação do teor de triacilglicerídeos, que demonstrou concordância com os métodos de referência. Já a caracterização do petróleo empregou a altíssima exatidão e resolução da espectrometria de massas por ressonância ciclotrônica de íons com transformada de Fourier, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) com as técnicas de ionização EASI e Electrospray (ESI). O presente trabalho representou ainda a primeira tese de doutorado no Brasil em petroleômica, descrevendo um método de análise que dispensa uma série de procedimentos analíticos dispendiosos e demorados, de maneira a conferir um alto grau de refinamento e desempenho à análise de petróleo. Foram estudados os compostos polares do petróleo que contêm os heteroátomos nitrogênio (N), enxofre (S) e oxigênio (O) na sua composição, sendo possível caracterizá-los por distribuição em porcentagem de classes de heteroátomos, número de carbonos e insaturações por double bond equivalents (DBE). Foi apresentada uma proposta de estudo de precisão para a metodologia de petroleômica-MS por meio da estimativa de repetitividade e reprodutibilidade, além do estudo comparativo de eficiência das técnicas de ionização ESI e EASI
Abstract: The chemical characterization of oils in a fast way and with minimal sample preparation is a challenge for modern analytical chemistry. The present study comprised the chemistry characterization of 15 vegetal oil samples and 6 samples of petroleum, demonstrating the versatility of the mass spectrometry (MS) technique in this area. Vegetal oils characterization was performed by an ambient ionization technique developed in Brazil, named Easy Ambient Sonic-Spray Ionization (EASI), and using a monoquadrupole mass analyzer with unitary resolution. EASI-MS detected for vegetable oils the composition of triacylglycerols (TAG), free fat acids and hydroperoxides using only one drop of oil and without sample preparation. The direct analysis provided by EASI-MS allowed us to propose also a quantitative method based on EASI MS data to determine the level of triacylglycerols of the vegetal oils. This method was in agreement with reference methods. For petroleum characterization, we used ultra-high accuracy and resolution of the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with EASI and electrospray (ESI) ionization. The present work describes results from the first doctorate thesis in Brazil dealing with petroleomic MS, a method of analysis that precludes a series of expensive and time-consuming analytical procedures and that can confer a high degree of refinement and performance to petroleum analysis. We have studied polar components of the petroleum containing nitrogen (N), sulphur (S) and oxygen (O) as heteroatoms in their composition. These components were classified according to the percentage distribution of heteroatoms, carbon number and unsaturations, as well as double bond equivalent (DBE). The study also evaluated precision for petroleomic MS via estimations of repeatability and reproducibility. The efficiencies of ESI and EASI for the petroleum analysis were also compared
Doutorado
Quimica Analitica
Doutor em Ciências

APA, Harvard, Vancouver, ISO, and other styles

29

Cabrita, Patrícia Alexandra Reis Nunes. "Produção de triacilgliceróis estruturados catalisada por lipases imobilizadas." Doctoral thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5214.

Full text

Abstract:

Doutoramento em Engenharia Alimentar - Instituto Superior de Agronomia
The aim of this study was the production of structured lipids (SL) containing medium-chain fatty acids (M) in positions sn-1,3 and long-chain fatty acids (L) in the sn-2 position(MLM type). These SL were obtained by acidolysis of virgin olive oil with caprylic or capric acid in n-hexane or in solvent-free media. Acidolysis reactions were catalysed by commercial lipase preparations from Thermomyces lanuginosa, Rhizomucor miehei and Candida antarctica (“Lipozyme TL IM”, “Lipozyme RM IM” and “Novozym 435”, respectively). The higest incorporation values of M were obtained in solvent-free media (19.9-30.4 mol%) than in the presence of n-hexane (13.6- 21.9 mol%). “Lipozyme RM IM” presented the best operational stability in consecutive batches (half-life time, t1/2, of 299h). The sn-1,3 selective recombinant Rhizopus oryzae lipase (r-ROL), produced by the methylotrophic yeast Pichia pastoris, was tested as alternative for the commercial lipases. The r-ROL was immobilized in Eupergit® C, in modified sepiolite or in Lewatit® VP OC 1600. Lewatit® VP OC 1600 showed to be the best support for r-ROL immobilization, since higher operational stability was observed when this lipase preparation was reused in consecutive batches with rehydration between batches (t1/2 =234h). r-ROL is a feasible biocatalyst for the production of MLM by acidolysis.

APA, Harvard, Vancouver, ISO, and other styles

30

Manuel, Chica Costa Ernesto. "Lipólise de triacilgliceróis no rúmen." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária. Instituto Superior de Agronomia, 2019. http://hdl.handle.net/10400.5/18980.

Full text

Abstract:

Dissertação de Mestrado em Engenharia Zootécnica/Produção Animal
A inclusão de suplementos lipídicos, geralmente compostos por triacilgliceróis, na dieta de ruminantes permite aumentar o seu desempenho produtivo e alterar a composição lipídica dos seus produtos. Sabe-se que os triacilgliceróis ingeridos são extensivamente hidrolisados no rúmen (i.e., lipólise), mas pouco se conhece sobre o comportamento cinético da lipólise de diferentes tipos de triacilgliceróis. O objetivo geral deste trabalho consistiu na avaliação da lipólise de diferentes triacilgliceróis (TGL-16:0/16:0/16:0, TGL- 18:0/18:0/18:0, TGL-18:1/18:1/18:1, TGL-18:2/18:2/18:2 e TGL-18:3/18:3/18:3) através de estudos in vitro com inóculo ruminal durante 0, 0,5, 2, 4 e 6 horas de incubação. Especificamente pretendeu-se avaliar na lipólise o efeito do comprimento da cadeia e grau de insaturação dos AG no triacilglicerol. Adicionalmente analisaram-se os produtos provenientes da bioidrogenação e síntese microbiana. Através dos resultados obtidos constatou-se que o desaparecimento dos triacilgliceróis testados aumentou significativamente (P<0,05) ao longo do tempo de incubação com os TGL-16:0, TGL- 18:1c9 e TGL-18:2n-6 e não se verificaram diferenças significativas (P=0,726) a partir das 0,5 horas no desaparecimento do TGL-18:3n-3 até às 6 horas de incubação. O TGL- 18:0 foi o que apresentou um menor grau de lipólise após 6 horas e o TGL-16:0 foi o que apresentou numericamente um maior grau de lipólise. Nas incubações com os TGL- 16:0 e TGL-18:0 ao longo das 6 horas não se verificou grandes diferenças na composição em ácidos gordos na fração dos ácidos gordos livres. Nas incubações com os TGL-18:1, TGL-18:2 e TGL-18:3, a fração dos ácidos gordos livres mostrou um padrão de ácidos gordos coerentes com os gerados durante as vias de bioidrogenação ruminal conhecidas do 18:1c9, 18:2n-6 e 18:3n-3, respetivamente. O desaparecimento de matéria seca assim como as variações na concentração de plasmalogénios, analisados na forma de dimetil acetais, e também dos ácidos gordos ramificados sugere-se que não houve inibição do crescimento microbiano. Conclui-se que a composição dos triacilgliceróis influencia pouco a sua suscetibilidade à lipólise no rúmen, no entanto em trabalhos futuros dever-se-ia aumentar o tempo de incubação in vitro, assim como testar outros lípidos, com diferentes composições em ácidos gordos.
ABSTRACT - Lipolysis of triacylglicerols in the rumen - The inclusion of lipid supplements, mostly comprised by triacylglycerols, in ruminant diets have been used to improve productive performance and to modify the lipid composition of their products in order to improve their nutrition value. It is well known that triacylglycerols are extensively hydrolyzed (i.e. lipolysis) in the rumen but it is not known if the lipolysis kinetics differ with different triacylglycerols. The main objective of this work was to evaluate the lipolysis of five triacylglycerols (TGL- 16:0/16:0/16:0, TGL-18:0/18:0/18:0, TGL-18:1/18:1/18:1, TGL-18:2/18:0/18:2 e TGL- 18:3/18:3/18:3) using in vitro incubations with rumen inoculum during 0, 0.5, 2, 4 and 6 hours. The specific aim was to evaluate the effect of the fatty acid length and level of unsaturation in the lipolysis. Additionally, the products from biohydrogenation and microbial synthesis were also analyzed. According to the results, we observed that the triacylglycerols disappearance increased significantly (P<0.05) with increasing incubation time when the TGL-16:0, TGL-18:1c9 e TGL-18:2n-6 were tested, but no significant differences (P=0,726) were observed between the 0.5 and 6 hours of incubation when TGL-18:3 was used. The TGL-18:0 showed the lowest level of lipolysis at 6 hours of incubation whereas the TGL-16:0 showed the numerically highest level. There was no great differences in the fatty acid composition of free fatty acid fraction during the 6 hours of incubation with TGL-16:0 and TGL-18:0. In incubations with TGL- 18:1, TGL-18:2 and TGL-18:3, the free fatty acid fraction showed a fatty acid profile consistent with the fatty acids formed during the ruminal biohydrogenation pathways of 18:1c9, 18:2n-6 and 18:3n-3, respectively. The dry matter disappearance as well as changes in the concentration of plasmalogens, analyzed as dimethyl acetals, and also the branched chain fatty acids concentration, suggest that there was no inhibition of growth or activity of the microbial population. Concluding, the composition of triacylglycerols little affected its susceptibility to lipolysis in the rumen, however in future work the incubation time should be increased beyond the 6 hours, and other lipids, with different fatty acid compositions, should be tested.
N/A

APA, Harvard, Vancouver, ISO, and other styles

31

Hasan, Haslina. "Development of an LC-MS/MS method for the analysis of triacylglycerols from meat and application in the discrimination of cooked meat products." Thesis, University of York, 2010. http://etheses.whiterose.ac.uk/1079/.

Full text

Abstract:

A single stage reversed phase high performance liquid chromatography (RP HPLC) separation of animal fat triacylglycerols (TAGs) has been developed for coupling with atmospheric pressure chemical ionization tandem mass spectrometry using an ion trap mass spectrometer. The method developed offers significant improvements on existing methods for TAG analysis, giving better resolution of TAGs with similar equivalent carbon number (ECN), and good separation of TAGs with odd ECN and TAG regioisomers of animal fats. Although the analysis times for chromatographic analysis of these TAGs are long, this is compensated by better separation of highly unsaturated TAGs. Development of an ultra high performance liquid chromatography method has reduced the run time by half, while maintaining separation and resolution. The TAG profiles of fats reflect their fatty acid (FA) compositions, showing a high proportion of unsaturated FAs for chicken and pork, whereas, saturated FAs are dominant in the major TAGs detected in beef and lamb. The improved RP HPLC separation of TAGs developed in this study has been shown to give more reliable discrimination of different animal species than previous methods including analysis of FAs as the methyl esters and RP HPLC separations of intact TAGs. All animal species separated well in the principal component analysis (PCA) plot of TAG profiles, whereas in the PCA plot of FA, chicken plots very close to pork fat, particularly ham. The profiles of TAGs in animal species highlight a number of components that are important for species discrimination. The meat products of different species (beef, pork, chicken and lamb) cooked by microwave, roasting and currying are separated well in the PCA scores plot. This work shows that the discrimination of meat from different animal species is possible for both raw and cooked meat products, and reveals that the differences produced by the various cooking methods were less than the variations observed between species. The loadings values for the scores plot of TAGs for raw and cooked meat products are similar to the raw meat in different animal species and have the same important descriptors for discrimination. Hence, analysis of intact TAGs in cooked food products has considerable potential for detection of adulteration of cooked meat-based food products.

APA, Harvard, Vancouver, ISO, and other styles

32

Fernandes, Gabriel Deschamps 1988. "Caracterização de lecitinas comerciais por espectrometria de massas ambiente com ionização sonic-spray." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256072.

Full text

Abstract:

Orientador: Daniel Barrera Arellano
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-19T21:15:47Z (GMT). No. of bitstreams: 1 Fernandes_GabrielDeschamps_M.pdf: 1854677 bytes, checksum: e57833484e8f9ad4a136187bed59d8d2 (MD5) Previous issue date: 2012
Resumo: Os fosfolipídios são definidos como o grupo de moléculas que contém um grupamento fosfato. Por apresentarem características anfipáticas, este grupo de moléculas se organiza naturalmente em bicamadas, originando as membranas dos seres vivos. Industrialmente são capazes de estabelecer interfaces óleo/água, possibilitando a formação e estabilização de emulsões. Este grupo de moléculas é bastante diverso quimicamente, sendo os principais componentes a fosfatidilcolina, fosfatidiletanolamina, fosfatidilserina, fosfatidilinositol, ácido fosfatídico e esfingomielina. A determinação e quantificação desses compostos é bastante laboriosa tanto nos meios industriais como acadêmicos, envolvendo, entre outras, etapas de digestão ácida e incineração. A espectrometria de massas desponta como uma técnica bastante favorável à análise de lipídios, englobando desde estudos clínicos até de biocombustíveis. Mais recentemente, as técnicas de espectrometria de massas com ionização ambiente facilitaram o acesso a este tipo de tecnologia, diminuindo os custos de implantação e principalmente de operação. A ionização ambiente por sonic-spray (EASI, easy ambient sonic-spray ionization) denota-se como uma técnica adequada à análise de lipídios, uma vez que não aplica alta voltagem e alta temperatura, prevenindo, portanto possíveis degradações destas moléculas. Este trabalho teve como objetivo, estudar a ionização de fosfolipídios (PL) e triacilgliceróis (TAG) frente à técnica EASI-MS, bem como, estudar a viabilidade técnica da caracterização de lecitinas comerciais por meio da técnica EASI-MS. Quanto à ionização dos lipídios, foi possível observar, nas condições de estudo, que dentro de uma mesma classe (PL ou TAG) a intensidade de ionização diminui com o aumento da cadeia dos ácidos graxos e aumenta com o aumento das insaturações. Para o estudo de caracterização foram utilizadas seis amostras de lecitina de soja comercial, obtidas por diferentes processos. As amostras foram diluídas em clorofórmio e submetidas à análise de EASI-MS, nos modos positivo e negativo. Nos espectros de EASI(+)-MS, os íons mais representativos foram os íons correspondentes à fosfatidilcolina e aos triacilgliceróis, enquanto que, nos espectros de EASI(-)-MS os íons mais representativos corresponderam à fosfatidiletanolamina, aos ácidos graxos livres e aos glicofosfolipídios. A técnica EASI-MS mostrou-se eficiente na caracterização das lecitinas comerciais. Sendo uma técnica rápida e que não exige preparo de amostra
Abstract: Phospholipids are defined as the group of molecules containing a phosphate grouping. As they have amphipathic characteristics, this group of molecules naturally organizes bilayer, origin the membranes of living organism and are able to establish an industrial oil / water interface, allowing the formation and stabilization of emulsions. This group of molecules is very chemically different; the main components are phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, phosphatidic acid and sphingomyelin. The determination and quantification of these compounds is very laborious for the academic and industrial circles, involving, among others, several steps, like acid digestion and incineration. Mass spectrometry is emerging as a very favorable tool of lipids analysis, since clinical and biofuel studies. Recently, the techniques of ambient mass spectrometry have facilitated the access to this type of technology, reducing deployment costs and especially the operation. Easy ambient sonic-spray ionization (EASI) denotes as a suitable technique to analyze the lipids, since it does not apply high voltage and high temperature, and thereby prevent possible degradation of these molecules. This work aimed to study the ionization of phospholipids (PL) and triacylglycerols (TAG) in EASIMS technique, as well as studying the technical feasibility of the characterization of commercial lecithins by EASI-MS. On the lipid ionization, it was observed, under the conditions of the study, that within the same class (TAG or PL) the ionization intensity decreases with increasing of fatty acids chains and increases with increasing of unsaturation. For characterization studies were used six samples of commercial soy lecithin, obtained by different processes. Samples were diluted in chloroform and analyzed for EASI-MS in positive and negative ion modes. In the spectra of EASI (+)- MS, the most representing ions are corresponding to triglycerides and phosphatidylcholine, whereas in the spectra of EASI (-)-MS the most representative ions correspond to the phosphatidylethanolamine, the free fatty acids and glicophospholipidios. The EASI-MS technique was efficient in the characterization of commercial lecithins. As a fast technique and does not require sample preparation
Mestrado
Tecnologia de Alimentos
Mestre em Tecnologia de Alimentos

APA, Harvard, Vancouver, ISO, and other styles

33

Bourque, Christine. "Evaluation of a functional oil composed of medium chain triacylglycerols, phytosterols and n-3 fatty acids on the cardiovascular risk profile of overweight women." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32765.

Full text

Abstract:

We examined the effect of a functional oil (FctO), with potential weight-controlling and blood lipid-lowering attributes, vs beef tallow as control (C), on the cardiovascular risk profile of overweight women. The FctO comprised energy expenditure-enhancing medium chain triacylglycerols, cholesterol-lowering phytosterols and triacylglycerol-suppressing n-3 fatty acids. In a randomized, single-blind, crossover design, inpatient trial, 17 women consumed each oil as part of a controlled, supervised, energy-adjusted diet for 27 days. Body weight decreased similarly during both dietary periods. Plasma total and LDL cholesterol levels decreased by 4.8% and 10.4% following FctO, and were lower by 9.0% and 16.4% respectively, after FctO vs C. HDL cholesterol and circulating triacylglycerol levels were unaffected by treatment, though HDL:LDL and HDL:total cholesterol ratios increased by 19.5% and 9.4% on FctO. Plasma total homocysteine levels were higher on FctO vs C. Plasma glutathione increased with FctO supplementation.
We conclude that consumption of FctO improves the overall cardiovascular risk profile of overweight women.

APA, Harvard, Vancouver, ISO, and other styles

34

Lima, Antonio Jefferson dos Passos. "Extração, caracterização e confirmação das estruturas dos ácidos graxos majoritários presentes no óleo da terminalia catappa linn (castanhola) através de técnicas espectroscópicas." Universidade Federal da Paraíba, 2016. http://tede.biblioteca.ufpb.br:8080/handle/tede/9011.

Full text

Abstract:

Submitted by Maike Costa (maiksebas@gmail.com) on 2017-06-21T12:55:32Z No. of bitstreams: 1 arquivototal.pdf: 4313605 bytes, checksum: edb0f819c041917885291efd9ed6923a (MD5)
Made available in DSpace on 2017-06-21T12:55:32Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4313605 bytes, checksum: edb0f819c041917885291efd9ed6923a (MD5) Previous issue date: 2016-02-02
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Terminalia catappa linn also known as castanets is belonging to the family of combretaceae and is found throughout the Brazilian coast. Although it is not a native species, it has ease germination and high resistance to salinity that lead it to become invasive. The fruits of castanets collected around UFPB campus showed almonds rich in oil with yield around 26% obtained by mechanical extraction. The triacylglycerides in the oil have showed a direct influence in the physical and chemical properties as acid value, iodine, peroxide, specific gravity and viscosity rheological factor. The results of these analyzes proved that the samples were in good condition of conservation. Furthermore, the results obtained from analytical thermogravimetry technics showed good thermooxidative stability to decomposition of the samples. The gas chromatography analysis coupled with mass spectrometer suggested that the palmitate, elaidate, linoleate and stearate as major methyl esters constituents of the triacylglycerides responsible for the evaluated properties.These esters were confirmed by the most important spectroscopic techniques to discuss structural elucidation of organic molecules such as FTIR, 1H and 13C NMR, COSY and HSQC.
A Terminália catappa linn também conhecida como castanhola, pertencente à família das combretaceae, é encontrada em todo litoral brasileiro. Apesar de não ser uma espécie nativa, sua facilidade em germinar e alta resistência à salinidade, tornou-a invasiva. Os frutos coletados desta espécie nas imediações da UFPB, apresentam amêndoas ricas em óleo e o rendimento obtido por extração mecânica foi em torno de 26 %. Os triacilglicerídeos que o compõe influenciam diretamente nos parâmetros físico e químicos avaliados como índice de acidez, iodo, peróxido, massa especifica e o fator reológico viscosidade. Estas análises comprovam que a amostra estudada apresentou bom estado de conservação. Este resultado foi corroborado com as técnicas analíticas de termogravimetria e através da oxidação acelerada por fluxo de calor, evidenciando que a amostra em estudo apresenta boa estabilidade em relação à decomposição termo-oxidativas. A análise em cromatografia gasosa acoplada ao espectrômetro de massas sugere os ésteres metílicos majoritários palmitato, elaidato, linoleato e estearato como constituintes dos triacilglicerídeos responsáveis pelas propriedades avaliadas. Estes foram confirmados por técnicas espectroscópicas como infravermelho, RMN 1H, RMN 13C, COSY e HSQC que são as mais importantes quando se discute sobre elucidação estruturais de moléculas orgânicas.

APA, Harvard, Vancouver, ISO, and other styles

35

Cagnon, Caroline. "Une approche de génétique classique pour l' isolement et la caractérisation de mutants affectés dans la remobilisation des lipides chez Chlamydomonas reinhardtii." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4012.

Full text

Abstract:

Les microalgues accumulent de grandes quantités d’huile, et sont de bons candidats pour la production de biocarburants. Mais des verrous techniques et biologiques doivent être levés pour une production rentable. Augmenter la teneur en huile par cellule et découvrir des protéine clés du métabolisme des triglycérides sont des objectifs importants. Nous avons mis en place une approche de génétique classique ciblée sur l’isolement de mutants d’insertion affectés dans la remobilisation des lipides de réserves suite à la re-supplémentation en azote après carence. Nous avons mis au point un protocole de criblage à haut débit basé sur la semi-quantification de ces lipides qui nous a permis d’isoler plus de 30 mutants. Nous avons identifié les loci d’insertion pour certains en utilisant la méthode Genome Walker. Le marqueur de résistance à l’antibiotique a été trouvéé dans des gènes codant pour des kinases, une protéine de type polycystine avec répétitions d’un domaine homologue de type lipoxygénase, des protéines du métabolisme de l’amidon, ou encore une méthyltransférase. Ces mutants forment un set de candidats devant être validés par complémentation pour une meilleure compréhension du métabolisme des lipides. Nous avons vu que la plupart des mutants défectueux dans la remobilisation des lipides de réserve sont aussi affectés dans celle de l’amidon. Ce lien potentiel entre les 2 processus est renforcé par le fait que dans 2 mutants connus de synthèse de l’amidon nous avons pu mettre en évidence un défaut de remobilisation des triglycérides. Ainsi, nous avons montré un lien d’interdépendance entre les dégradations des 2 formes majoritaires de réserves carbonées des microalgues
Microalgae are able to accumulate high amounts of oil reserves, which make them promising candidates for biofuel production. Nevertheless, some technical and biological bottlenecks have to be overcome before a profitable industrial production. Increasing oil content per cell and discovering key proteins of oil metabolism is a major goal. We took a forward genetic approach and focused on isolating insertional mutants affected in oil remobilization following nitrogen resupply after a starvation phase. We setup and developed a medium- to highthroughput semi-quantitative oil content screening protocol, which has enabled isolation of >30 mutants. We identified the insertion loci in some of these mutants through the “genome walker” PCR-based method. The antibiotic marker was found to be inserted in genes encoding various proteins including serine-threonine kinases, a polycystin-related protein containing repetitions of a lipoxygenase homology domain, an E3 ubiquitin ligase, a starch metabolism protein and a methyltransferase. Mutants isolated provide a first set of candidate genes that remain to be validated by complementation and should contribute to a better understanding of lipid homeostasis in green microalgae. During the course of this work, we observed that most mutants defected in oil remobilization were also impaired in starch degradation. The occurrence of a link between the degradation of starch and oil was further strengthened by the fact that in two known starch-less mutants the oil remobilization process was found to be defected. This is the first evidence of an interdependency between the degradation processes of the major types of carbon reserves in microalgae

APA, Harvard, Vancouver, ISO, and other styles

36

Nguyen, Thi hoa mai. "Etude du métabolisme lipidique chez Clamydomonas reinhardtii : Approches de protéomique et de génétique." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4006.

Full text

Abstract:

La capacité des microalgues à accumuler des quantités importantes de lipides de réserve font de ces organismes de bons candidats pour envisager une production durable de biocarburants (biodiesel). Cependant, des verrous d’ordre technologique et biologique persistent avant d’atteindre une production économiquement viable. Dans le but de mieux comprendre les mécanismes et biosynthèse et d’accumulation des lipides chez les microalgues et de proposer des voies d’amélioration biotechnologiques, nous avons développé deux approches expérimentales complémentaires en utilisant la microalgue Chlamydomonas reinhardtii comme modèle. La première a été de caractériser par des techniques de protéomique et de lipidomique la composition des gouttelettes lipidiques s’accumulant en réponse à une carence en azote. Les données de protéomique nous ont permis de montrer que les gouttelettes lipidiques étaient des structures cellulaires dynamiques impliquées non seulement dans le stockage, mais aussi dans la biosynthèse, la remobilisation et le « trafficking » des lipides. Les protéines identifiées au cours de cette étude nous fournissent des gènes cibles d’intérêt pour mieux comprendre les voies de biosynthèse des triacylglycérols et accroître l’accumulation d’huile. La seconde approche, de génétique formelle, a consisté à rechercher puis à caractériser des mutants isolés à partir d’une banque de mutants d’insertion de C. reinhardtii. Deux mutants d’intérêt, l’un affecté dans la composition en acides gras (crfad7) et l’autre capable d’accumuler des lipides en l’absence de stress (coa1, pour constitutive oil accumulator 1), ont été isolés
The ability of microalgae to accumulate high amounts of reserve lipids makes these organisms good candidates for the production of sustainable biofuel (biodiesel). However, both technological and biological bottlenecks remain to be overcome before profitable production is reached. With the aim to better understand lipid metabolic pathways in microalgae and further propose new strategies for biotechnological improvement, we have developed two complementary experimental approaches in the model microalga Chlamydomonas reinhardtii. As a first approach, we performed a proteomic and lipidomic characterization of oil bodies isolated from nitrogen-deprived cells. Based on proteomic data, we have concluded that oil bodies are dynamic structures involved not only in the storage, but also in oil biosynthesis, degradation and lipid homeostasis. The proteins identified in this study should provide useful targets for genetic studies aiming at increasing our understanding of triacylglycerol synthesis and further improve intracellular oil accumulation. The second approach, based on the development of a forward genetic screen, aimed at searching and further characterizing mutants isolated from a C. reinhardtii insertion library. Two mutants of interest, one affected in the fatty acid composition (crfad7), the other (coa1, for constitutive oil accumulator 1) able to accumulate reserve lipids in the absence of stress, have been isolated. The crfad7 mutant, affected in the expression of the unique ω3 fatty acid desaturase present in the C. reinhardtii genome, has been complemented and subjected to extensive phenotypical characterization

APA, Harvard, Vancouver, ISO, and other styles

37

Ming, Chiu Chih. "Síntese de lipídios estruturados por interesterificação de gordura de frango e triacilgliceróis de cadeia média." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/9/9133/tde-17072006-181750/.

Full text

Abstract:

Os lipídios estruturados (LEs) constituem uma classe lipídica caracterizada pela presença de triacilgliceróis (TAGs) projetados de modo a apresentarem em sua estrutura química ácidos graxos (AGs) com características desejáveis. Na atualidade, estes compostos representam um desafio tecnológico e uma nova fronteira no desenvolvimento de produtos nutricionalmente superiores. Estes TAGs reestruturados são sintetizados através da mistura de óleos e gorduras e de posterior interesterificação química ou enzimática. O rearranjo de AGs nestas moléculas resulta em produtos com características físicas, químicas e nutricionais diferentes das dos lipídios originais. Devido à capacidade potencial para a redução do risco de doenças, também podem ser considerados alimentos funcionais por apresentarem vantagens clínicas que se encontram associadas aos seus AGs e à estrutura peculiar de sua molécula lipídica formada pela interesterificação. A incorporação de ácidos graxos de cadeia média (AGCM) aos TAGs, como o caprílico e cáprico, e de ácidos graxos monoinsaturados (AGMI) como o oléico (w-9), tem sido considerada de grande importância na elaboração de alimentos funcionais de origem lipídica, uma vez que proporcionam rápida fonte de energia e reduzem o risco de enfermidades cardiovasculares. Os objetivos do projeto foram analisar as interações produzidas em misturas binárias e ternárias de triacilgliceróis de cadeia média e longa pela análise das propriedades físicas e químicas das misturas e realizar a modificação das misturas por interesterificação química, visando a obtenção de LEs, com posterior análise química e física de suas propriedades. Foram utilizadas gordura abdominal de frango, sua estearina e triacilgliceróis de cadeia média. Foi empregado um planejamento de dez experimentos. Para as respostas analíticas foi aplicado um modelo de regressão múltipla, do tipo cúbico especial. Os resultados foram representados em diagramas triangulares. Os LEs obtidos apresentaram 14,8 a 58,4% de AGCM, 15,7 a 37,2% de ácidos graxos saturados, 19,2 a 47,5% de AGMI e 6,7 a 15,2% de ácidos graxos essenciais. A estearina de frango teve influência sobre as propriedades de pontos de amolecimento e fusão, consistência e conteúdo de gordura sólida. Após a reação houve formação de grupos de TAGs não existentes nas amostras originais. A técnica de DSC possibilitou distinguir entre misturas de gorduras e LEs, além de permitir a visualização de modificações nas misturas decorrentes da interesterificação. A composição triacilglicerídica foi fundamental para compreender o comportamento das misturas interesterificadas, mesmo diante da dificuldade na identificação dos TAGs individuais.
Structured triacylglycerols are generally any fats that are modified or restructured from natural oils and fats, or fatty acids therefrom, having special functionality or nutritional properties for edible or pharmaceutical purposes. These restructured triacylglycerols are synthesized by blending and chemical or enzymatic interesterification reaction of oils and fats. The fatty acids rearrangement in these molecules results in products with physical, chemical and nutritional characteristics that are different from the original lipids. These compounds can be considered functional foods when they are able to reduce the risk of diseases. Their clinical advantages are associated with the peculiar structure of the lipid molecule formed by interesterification. The incorporation of medium chain and monounsaturated, is considered of great importance in the lipidic functional foods formulation. These kinds of lipids are a quick energy source and could prevent cardiovascular diseases. The purposes of this study were to analyze the interactions that occur in binary and ternary fat blends between medium and long chain triacylglycerols and their structured triacylglycerols obtained by chemical interesterification through the analysis of their physico-chemical properties. The raw material utilized in this research was abdominal chicken fat, its stearin and medium chain triacylglycerols. The experimental design presented 10 samples corresponding to 10 different blend proportions. A mathematical model of multiple regression of the special cubic type was used to obtain the analytical responses. The results were represented in triangular diagrams. The synthesized structured triacylglycerols presented from 14.8 to 58.4% of medium chain fatty acids, from 15.7 to 37.2% of saturated fatty acids, from 19.2 to 47.5% of monounsaturated fatty acids, and from 6.7 to 15.2% of essential fatty acids. The addition of stearin influenced the softening and melting points, consistency, and solid fat content of chicken fat. After interesterification new types of triacylglycerols groups were formed. The DSC method allowed distinguishing natural fat mixtures from structured triacylglycerols. The triacylglycerols composition had a great importance in understanding the interesterified blends behavior, even with the difficulty in the individuals triacylglycerols identification.

APA, Harvard, Vancouver, ISO, and other styles

38

Melo, Ingrid Sofia Vieira de. "Perfil em ácidos graxos do tecido hepático de ratos submetidos a dieta cetogênica rica em trienatina." Universidade Federal de Alagoas, 2011. http://repositorio.ufal.br/handle/riufal/660.

Full text

Abstract:

Dietary lipids determine the incorporation and fatty acid composition of the organism, especially in organs most susceptible to its modulating action on membrane phospholipids esterified fatty acids, such as the liver. Ketogenic diets, widely used to treat various disorders, often use long-chain triacylglycerols, however, medium chain triglycerides are considered an alternative source, since they are digested, absorbed, oxidized and removed from circulation more rapidly than long chain triacylglycerols. In addition, it lead to the formation of ketone bodies quickly, without the influence of hormonal or nutritional factors. To contribute to the discussion, this paper presents a review chapter, entitled Mitochondrial dysfunction in nonalcoholic fatty liver disease, which gathers information on oxidative stress and consequent mitochondrial dysfunction in the context of liver disease. It also presents an original article, entitled Fatty acid profile in liver tissue of rats subjected to ketogenic diet rich in trienantin, which discusses the effects of a ketogenic diet based on trienantin, a homogeneous triacylglycerol composed of enantic (heptanoic) acid, or based on soybean oil on this profile. The livers of animals fed the ketogenic diet showed a significant reduction in the concentration of monounsaturated fatty acids, 9-hexadecenoic and 9-octadecenoic compared to control group, suggesting a potential reduction in the activity of the enzyme Stearoil-CoA Desaturase 1. Additionally, the group fed trienantin showed increased levels of octadecanoic acid compared to control group, which corroborated the hypothesis of decreased enzyme activity in this group. Thus trienantin in ketogenic proportions exerted modulatory effects similar to soybean oil, widely used conventional oil, despite the differences in fatty acid composition between these two fat sources. The study showed that rats fed a ketogenic diet experienced modulation of fatty acid profile of hepatic lipids and that in the conditions set forth herein, this modulation was due especially to the nature of the ketogenic diet itself and not to the type of oil used in their preparation.
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Os lipídios dietéticos determinam a incorporação e a composição em ácidos graxos do organismo, especialmente em órgãos mais susceptíveis a sua ação moduladora sobre os ácidos graxos esterificados a fosfolipídios de membrana, como, por exemplo, o fígado. Dietas cetogênicas, amplamente utilizadas para o tratamento de diversas desordens, normalmente utilizam triacilgliceróis de cadeia longa, porém, triacilgliceróis de cadeia média são considerados uma fonte alternativa, visto que são digeridos, absorvidos, oxidados e removidos da circulação mais rapidamente que os de cadeia longa. Além disso, levam à formação de corpos cetônicos de forma acelerada, não sofrendo a influência de fatores hormonais ou nutricionais. Visando contribuir com a discussão, a presente dissertação apresenta um capítulo de revisão, intitulado Disfunção mitocondrial na doença do fígado gorduroso não alcoólica, que reúne informações sobre o estresse oxidativo e a conseqüente disfunção mitocondrial, no contexto desta doença hepática. E, um artigo original, intitulado Perfil em ácidos graxos do tecido hepático de ratos submetidos à dieta cetogênica rica em trienantina, que discute os efeitos de dieta cetogênica à base de trienantina, um triacilglicerol homogêneo do ácido enântico (heptanóico), ou de óleo de soja, sobre tal perfil. Os fígados dos animais alimentados com as dietas cetogênicas apresentaram redução significativa na concentração de ácidos graxos monoinsaturados, 9-hexadecenóico e 9-octadecenóico, quando comparados ao grupo Controle, sugerindo uma possível redução na atividade da enzima Estearoil-CoA Dessaturase 1. Adicionalmente, o grupo alimentado com trienantina apresentou aumento dos níveis de ácido octadecanóico, quando comparado ao grupo Controle. Assim, a trienantina, em proporções cetogênicas, exerceu efeito modulador similar ao do óleo de soja, um óleo convencional largamente utilizado, apesar das diferenças na composição em ácidos graxos entre essas duas fontes lipídicas. Neste estudo constatou-se que os ratos alimentados com dieta cetogênica sofreram modulação do perfil em ácidos graxos dos lipídios hepáticos e que, nas condições aqui estabelecidas, tal modulação se deveu especialmente à natureza cetogênica da dieta per si e não ao tipo de óleo empregado em sua elaboração.

APA, Harvard, Vancouver, ISO, and other styles

39

ARRUDA, Andréa Leão de Lima. "Separação de ácidos graxos livres e triacilgliceróis por destilação a vácuo." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/17855.

Full text

Abstract:

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-09-16T14:17:18Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Andréa Leão_Ver_Final.pdf: 2849890 bytes, checksum: cd4d0770cfce99861e2cf216c67ed0fb (MD5)
Made available in DSpace on 2016-09-16T14:17:18Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Andréa Leão_Ver_Final.pdf: 2849890 bytes, checksum: cd4d0770cfce99861e2cf216c67ed0fb (MD5) Previous issue date: 2016-02-23
ANP
O presente estudo propõe a separação entre os triacilgliceróis (TAGs), principais constituintes dos óleos vegetais, e ácidos graxos livres (AGLs) através do processo de destilação a vácuo. A possibilidade dessa separação consiste na considerável diferença de volatilidade entre os AGLs e os TAGs. Foram preparadas misturas modelo aos óleos residuais, ou seja, combinações em diferentes proporções em massa de óleo de soja refinado (OS) e o reagente ácido oleico p.a (AO). As misturas foram destiladas nas pressões reduzidas de 0,13; 0,40; 0,67 e 1,33 kPa, sendo o processo realizado em batelada em um único estágio, sem refluxo. As amostras foram caracterizadas antes e após o processo de destilação a vácuo quanto: à massa específica, ao teor de água, ao teor de AGL (%) e à composição de ácidos graxos por cromatografia gasosa. Posteriormente, foram definidos os componentes modelo de TAG e AO e a estimativa dos parâmetros termofísicos das misturas para a simulação do processo de destilação a vácuo no software Aspen Plus V8.8, utilizando tanques flash não adiabáticos em série. O modelo termodinâmico usado foi o Non-Random Two-Liquid (NRTL). As curvas de destilação experimentais da mistura de 89,45% de OS e 10,55% de AO em massa foram melhor representadas pelas curvas de destilação simuladas, apresentando o percentual de desvios médios quadráticos de 2,5; 2,2; 2,4 e 2,5% para operações realizadas em pressões reduzidas de 0,13; 0,40; 0,67 e 1,33 kPa, respectivamente. Os dados de massa específica a 20°C dos produtos das destilações, resíduos e destilados, foram semelhantes aos do OS e AO, respectivamente. Os teores de água dos destilados (0,024% a 0,059%) e dos resíduos (0,001% a 0,014%) estão em níveis adequados para o emprego das reações de esterificação e transesterificação para a produção de biodiesel. Os teores de ácidos graxos livres dos resíduos obtidos após as destilações ficaram dentro da faixa de 0,4% a 1,2%, indicando processo de separação por destilação a vácuo efetivo.
This study proposes the separation of triacylglycerols (TAG), main constituent of vegetable oils, and free fatty acids (FFA) through the vacuum distillation process. The possibility of this separation is the considerable difference in volatility between the FFA and the TAG. Mixtures were prepared with model waste oil, or combinations of different mass ratios of refined soybean oil (SO) and the reagent oleic acid (OA). The mixtures were distilled at reduced pressures of 0.13; 0.40; 0.67 and 1.33 kPa, the process being carried out in batches in a single stage, without reflux. The samples were characterized before and after the vacuum distillation process as: the specific gravity, the water content, the FFA content (%) and the fatty acid composition by gas chromatography. Subsequently, the components were defined template TAG and OA and the estimation of parameters of mixtures thermophysical to simulate the vacuum distillation process in Aspen Plus v8.8 software using non-adiabatic flash tanks in series. The thermodynamic model used was the Non-Random Two-Liquid (NRTL). Experimental distillation curves of mixing 89.45% of SO and 10.55% of mass OA were best represented by simulated distillation curves, showing the percentage of mean deviation squared of 2.5; 2.2; 2.4 and 2.5% for operations in reduced pressures of 0.13; 0.40; 0.67 and 1.33 kPa, respectively. The specific mass of data at 20°C the distillation of the products, residues and distillates were similar to SO and OA, respectively. The content of distilled water (0.024% to 0.059%) and waste (0.001% to 0.014%) were at adequate levels for the use of esterification and transesterification reactions for biodiesel production. The contents of free fatty acids from residues obtained after distillations were within the range of 0.4% to 1.2%, indicating a separation process by distillation under vacuum effective.

APA, Harvard, Vancouver, ISO, and other styles

40

Oliveira, Etienne Sampaio. "Desenvolvimento de biossensor amperométrico em interface água/óleo utilizando de eletrodos de Au, PtPb/TiOx." reponame:Repositório Institucional da UFABC, 2017.

Find full text

Abstract:

Orientador: Prof. Dr. Hugo B. Suffredini
Tese (doutorado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciência e Tecnologia/Química, 2017.
Neste trabalho, foi abordado o desenvolvimento de um biossensor para estimar a concentração de triacilgliceróis derivados da síntese in loco de glicerol, produzido pela hidrólise de azeite de oliva catalisada por lipases, em um sistema do tipo interface líquido-líquido constituído por duas fases líquidas imiscíveis entre si.A técnica proposta neste trabalho consiste em uma inovação na área de eletroanalítica pois permite a detecção direta de compostos eletroativos em matrizes hidrofóbicas sem a necessidade de pré-tratamentos complexos. Eletrodos de Au, preparados a partir de CD-ROM¿s graváveis, apresentaram maiores valores de sensibilidade, na faixa de trabalho de 0,1 a 1,0 mmol L-1. A enzima foi imobilizada quimicamente sob o CDtrodo de ouro por meio de ligações cruzadas com glutaraldeído. Porcentagens de 5 a 75% de óleo de azeite foram adicionadas a 2,0 mL de Nujol® e, a temperatura de 30ºC foi observado o aumento da densidade de corrente. Um patamar se estabilizou após 10minutos de experimento cronoamperométrico no potencial de oxidação do glicerol em 0,3 V vs.SCE, tempo inferior com relação aos resultados obtidos por métodos colorimétricos. Também foi observada boa repetibilidade para um mesmo eletrodo com desvio de 4,44%pelo prazo de 5 dias consecutivos,armazenando o biossensor em solução tampão fosfato pH 7,5 e após prévia limpeza eletroquímica.Desta forma, conclui-se que o biossensor desenvolvido neste trabalho simples de ser fabricado, possuindo funcionamento adequado e boa resposta quanto à sensibilidade e especificidade para a molécula de glicerol, de modo que sua aplicação torna-se viável tanto para espécies em concentrações mínimas quanto em altas concentrações.
In this work, we discussed the development of a biosensor to estimate the concentration of triacylglicerol¿s in oil from the synthesis in loco of glycerol by hydrolysis of olive oil catalyzed by lipases in a liquid-liquid interface system consisting of two immiscible liquid. The use of interfaces in electrochemistry is not necessarily new study but represent an innovation in the field of electroanalytical, since it allows the direct detection of electroactive compounds in hydrophobic matrices without the need for complex pretreatment steps. Gold electrode presented a higher sensitivity value when compared to other electrodes in the concentration range of 0.1 to 1.0 mmol L-1. The enzyme was chemically immobilized in the gold electrode by crosslinking by glutaraldehyde 0.2%. Percentages of 5 to 75% of olive oil were added on 2.0 mL of Nujol ® and a temperature of 30 °C, increase of current densities was observed, with stabilization after 10 minutes of chronoamperometric experiment at an oxidation potential of glycerol in 0.3 V vs. Ag/AgCl, lower time in relation to the results obtained by colorimetric methods. Good repeatability of the experiments was also observed during 5 consecutive days, with a relative error of 4,44%, by storing the biosensor in phosphate buffer pH 7.5 and after previous electrochemical cleaning. Thus, it is possible to concluded that the biosensor developed in this work is easy to manufacture and simple to operate, presenting good sensitivity and specificity for the glycerol molecule. Its application in biological and organic matrices becomes viable as an alternative to the conventional methods of detection of TAG¿s.

APA, Harvard, Vancouver, ISO, and other styles

41

Le, moigne Damien. "Fonction de la protéine Seipin dans la biogénèse des gouttelettes lipidiques chez la diatomée Phaeodactylum tricornutum." Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALV110.

Full text

Abstract:

Les microalgues englobent des organismes photosynthétiques unicellulaires dont la diversité couvre une large partie de l’arbre du vivant. Elles colonisent une large variété d’environnements et sont régulièrement soumises à de nombreux stress biotiques et abiotiques. En réponse à ces stress, des gouttelettes lipidiques (LD) peuvent être produites. Les LD sont des organelles composés d’un cœur hydrophobe, contenant majoritairement des triacylglycerols (TAG), délimité par une monocouche de glycérolipides dans laquelle de nombreuses protéines sont enchâssées. Les LD sont présentes dans quasiment tous les organismes vivants et sont impliquées dans des fonctions variées comme le stockage de carbone et de molécules riches en énergie, le remodelage de lipides membranaires, la synthèse et le stockage de molécules hydrophobes, le stockage de carbone ou de molécules riches en énergie… De plus en plus de fonctions leur sont attribuées et les LD sont désormais considérées comme des organelles à part entière, extrêmement dynamiques et douées d’une grande plasticité autant dans leur composition en lipides que dans le cortège protéique dont elles sont équipées.La biogenèse des LD se fait à partir du système endomembranaire et sous contrôle de machineries moléculaires complexes. Dans ce processus, la protéine Seipin est un acteur majeur et a été caractérisée dans de nombreux organismes (plantes, animaux, levures). Cette protéine transmembranaire forme un oligomère inséré dans la membrane du réticulum endoplasmique et intervient au niveau fonctionnel sur différents aspects de la biogénèse de la LD. Elle est par exemple impliquée dans l’orientation du bourgeonnement de la LD, dans le contrôle de la taille des LD et dans le contrôle du flux de TAG dans la LD.Chez la diatomée oléagineuse Phaeodactylum tricornutum, un isoforme de Seipin (PtSeipin) a été préalablement identifié ; les travaux présentés ici ont eu pour but de la caractériser fonctionnellement. En combinant des approches de prédictions de structure, de phylogénie, de microscopie, de lipidomique et de protéomique, nous avons pu mettre en évidence plusieurs caractéristiques uniques de PtSeipin. Nous avons pu constater que les Seipin de diatomées et plus généralement de stramenopiles sont phylogénétiquement plus proches de celles des animaux et des champignons que des plantes et des algues vertes. Nous avons également pu établir que la perte de fonction de PtSeipin aboutissait à un phénotype fort, avec la formation de LD surdimensionnées comme cela est observé chez d’autres espèces. En revanche, de manière tout à fait unique, nous avons observé une accumulation spectaculaire de TAG, notamment en situations de stress, ce qui suggère que des mécanismes de régulation supplémentaires et spécifiques sont impliqués dans la formation de la LD chez P.tricornutum. Enfin, l’analyse des protéomes de LD purifiées chez des mutants PtSeipin ont révélé notamment que la protéine StLDP, décrite comme la protéine majeure des LD, n’y est plus recrutée. Ces résultats ouvrent de nouvelles perspectives de recherche fondamentale, notamment dans la recherche de protéines partenaires de la Seipin et dans l’étude fine de ses domaines fonctionnels. En outre, ces résultats apportent également des éléments nouveaux dans la recherche appliquée aux domaines des biocarburants de dernière génération
Microalgae encompass unicellular photosynthetic organisms whose diversity is represented throughout the tree of life. They colonize a variety of environments and are regularly subjected to numerous biotic and abiotic stresses. In response to these stresses, lipid droplets (LDs) can be produced. LDs are organelles composed of a hydrophobic core, predominantly containing triacylglycerols (TAGs), surrounded by a monolayer of glycerolipids embedded with numerous proteins. LDs are present in nearly all living organisms and are involved in various functions such as carbon and energy storage, remodeling of membrane lipids, synthesis and storage of hydrophobic molecules, and more. Increasingly, new functions are attributed to them, and LDs are now considered distinct organelles, highly dynamic and flexible, both in their lipid composition and protein complement.The biogenesis of LDs occurs within the endomembrane system and is under the control of complex molecular machineries. In this process, the protein Seipin plays a major role and has been characterized in numerous organisms (plants, animals, yeast). This transmembrane protein forms an oligomer inserted into the endoplasmic reticulum membrane and functionally influences various aspects of LD biogenesis. For example, it is involved in determining LD budding orientation, controlling LD size, and regulating the TAG flux within LDs.In the oleaginous diatom Phaeodactylum tricornutum, an isoform of Seipin (PtSeipin) has previously been identified, and the research presented here aimed to characterize its function. By combining structural prediction, phylogenetic, microscopy, lipidomic, and proteomic approaches, we have highlighted several unique features of PtSeipin. We observed that Seipin in diatoms and more broadly in stramenopiles are phylogenetically closer to those in animals and fungi than to photosynthetic organisms like plants and green algae. We also established that the loss of PtSeipin function leads to a pronounced phenotype, with the formation of oversized LDs, as observed in other species. However, uniquely, we observed a dramatic accumulation of TAGs, particularly under stress conditions, suggesting that additional specific regulatory mechanisms are involved in LD formation in P. tricornutum. Finally, the analysis of purified LD proteomes in PtSeipin mutants revealed that the protein StLDP, described as the major LD protein, is no longer recruited. These results open up new avenues for fundamental research, particularly in the search for Seipin partner proteins and the detailed study of its functional domains. Additionally, these findings also provide new insights for applied research in the field of next-generation biofuels

APA, Harvard, Vancouver, ISO, and other styles

42

Degraeve, Guilbault Charlotte. "Caractérisation des glycérolipides et de la dynamique de remodelage en chaines acyles chez Ostreococcus tauri." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0825/document.

Full text

Abstract:

La picoalgue verte marine Ostreococcus tauri est un eucaryote minimal développé en système modèle et qui a servi de ressource de gènes en biologie des lipides. Des informations détaillées sur ces caractéristiques lipidiques étaient cependant manquantes. Lors de ma thèse j’ai caractérisé le glycérolipidome d’O. tauri et ai cherché à déterminer quelles sont les cibles enzymatiques responsables de la dynamique des acides gras (FA) et de la régulation du métabolisme lipidique en réponse à des modifications de l’environnement (carences nutritives et refroidissement). O. tauri présente des caractéristiques uniques de composition en lipides et en FA mixtes entre les algues vertes et les Chromalveolates, et a été validé comme espèce modèle pour la classe des Mamiellophyceae. L’acide docosahexaénoïque (DHA) est confiné dans les lipides présumés extraplastidiaux : le phosphatidyldimethylpropanethiol (PDPT) et le bétaïne-lipide diacylglyceryl-hydroxymethyl-trimethyl-β-alanine (DGTA), tous deux marqueurs lipidiques des Chromalveolates. Les lipides plastidiaux de type procaryotique sont caractérisés par une prépondérance de FA polyinsaturés (PUFA) en C18 n-3, le 18:5 n-3 étant restreint aux galactolipides. Le 16:4 n-3, PUFA typique des galactolipides des microalgues vertes, est également un composant majoritaire des lipides extraplastidiaux chez O. tauri. Les triacylglycérols (TAG) présentent tout le panel d’acides gras d’O. tauri et leurs combinaisons moléculaires indiquent une origine plastidiale majoritaire. La carence azote provoque une forte accumulation de TAG, notamment des espèces présentant des combinaisons sn-1/sn-2 en 18:X/16:X et s'accompagne d'un transfert de carbone du phosphatidylglycérol (PG) et du monogalactosyldiacylglycérol (MGDG) aux TAG ce qui indique une contribution croissante de la voie plastidiale à la synthèse des TAG. Des expériences préliminaires de RT-qPCR sur des gènes du métabolisme des TAG révèlent une forte activation transcriptionnelle de certaines diacylglycérol acyltransférases (DAGT). Les carences nutritives répriment sévèrement l’activité Δ6 désaturase, générant une inversion du ratio 18:3/18:4 dans les lipides plastidiaux qui se répercute dans les TAG. La régulation fine et dynamique de ce ratio suggère un rôle important du 18:3 et du 18:4 dans les membranes plastidiales. Le refroidissement engendre une augmentation spécifique du 18:5 des galactolipides. La recherche active de la désaturase responsable de ce phénotype par une approche d'expression de gènes candidats en systèmes homologue et hétérologues (S. cerevisiae, N. Benthamiana) a conduit à l’indentification de deux Δ6 désaturases plastidiales jamais caractérisées dans d'autres systèmes. Celles-ci possèdent des spécificités non redondantes et originales entre elles et par rapport à l'acyl-CoA-Δ6 d'O. tauri
The marine green picoalga Ostreococcus tauri is a minimal eukaryote implemented as model system that has been used as gene resource for lipid biology. Detailed information about its lipidic features was however missing. During my PhD, I characterized O. tauri glycerolipidome and associated dynamics under environmental stresses such as nutrient starvations and chilling and investigated transcriptional variations of putative target enzymes responsible for these changes. O. tauri which could be validated as model for related species of the class Mamiellophyceae, was found to display unique lipidic features related to both green and Chromalveolates microalgae. Docosahexaenoic acid (DHA) is confined to presumed extraplastidial lipids i.e. phosphatidyldimethylpropanethiol (PDPT) and the betaine lipid diacylglyceryl-hydroxymethyl-trimethyl-β-alanine (DGTA); all of these compounds are hallmarks of Chromalveolates. Plastidial lipids found to be of prokaryotic type are characterized by the overwhelming presence of C18 n-3 polyunsaturated FA (PUFA), 18:5 n-3 being restricted to galactolipids. C16:4 n-3, an FA typical of green microalgae galactolipids, also was a major component of O. tauri extraplastidial lipids. Triacylglycerols (TAGs) display the complete panel of FAs, and their molecular combinations designate a major plastidial origin of DAG precursors. Nitrate starvation greatly increases TAG content, in particular 18:X/16:X (sn-1/sn-2) combinations, and was associated with the transfer of carbon from phosphatidylglycerol (PG) and monogalactosyldiacylglycerol (MGDG) to TAG indicating an increased contribution of the plastidial pathway to the TAG synthesis. Preliminary RT-qPCR experiments on TAG metabolism genes revealed an important transcriptional activation of some diacylglycerol acyltransferases (DGAT). Nutrient starvations severely repress Δ6 desaturase activity and result in the inversion of the 18:3/18:4 ratio in plastidial lipids that was feedback into TAG. The fine-tuning and dynamic regulation of the 18:3/18:4 ratio suggests an important physiological role of these FAs in photosynthetic membranes. Chilling generates an increase of 18:5 in galactolipids. The active quest for the desaturases responsible for this phenotype was achieved by expressing candidate genes in homologuous and heterologous (S. cerevisiae, N. Benthamiana) systems and led to the identification of two yet uncharacterized plastidial Δ6 desaturases. These desaturases display original and non-redundant specificity between each other and with the previously characterized in O. tauri Δ6 acyl-CoA desaturase

APA, Harvard, Vancouver, ISO, and other styles

43

Lucena, Ana Luiza de Melo. "Avaliação toxicológica subcrônica de dieta cetogênica à base de trienantina em ratos jovens." Universidade Federal de Alagoas, 2007. http://repositorio.ufal.br/handle/riufal/621.

Full text

Abstract:

The classic ketogenic diet, rich in long chain triacylglycerols (LCT), is characterised by a high concentration of lipids and a low concentation of carbohydrates and proteins, promoting ketonemia and ketonuria, a property used in the treatment of disorders that affect cerebral metabolism and function, for example epilepsy resistant to medication. Medium chain triacylglycerols (MCT) are considered alternative substrates to LCT in the production of this diet, to promote a more rapid increase in the levels of the body´s blood ketones. Trienantin, a medium chain triacyglycerol from enantic fatty acid (7:0), has been used with success with children suffering hereditary metabolic syndromes, but has had few studies about its toxicological effects. The objective of this dissertation was to evaluate the toxicity of a subchronic consumption of a ketogenic diet with a trienantin base on young rats, and is submitted in the form of two articles. The first, under the name of: Substitution of LCT with MCT in nutritional therapy: an emphasis on ketogenic therapy presents a revision of the ketogenic diet, comparing the data of LCT and MCT in animal and clinical studies. The more rapid ketonemia promoted by MCT allows a lower quantity of lipids and a greater proportion of proteins and carbohydrates, enhancing the palatability of the diet. The effect of replacing LCT with MCT on physiological parameters, such as serum lipid profile, remains controversial and requires additional studies to comprehend the repercussions of this class of lipids on human health. The second article entitled: Toxicological evaluation of a subchronic ketogenic diet based upon trienantin in young rats deals with an experimental study of male Wistar rats in which 3 groups (n=10), named according to their received diet: Control (diet pattern AIN-93) KetoTAGC7 (ketogenic based upon AIN-93G: modified to contain 4% soy oil, 25.79% trienantin and 40% margarine) and Keto TAGsoy (ketogenic based upon soya: AIN-93G modified to contain 29.79% soya oil and 40% margarine). The proportion of lipid:carbohydrate+protein in the ketogenic diets was 3.5:1 (control diet, 1:11.8) and the experimental duration was 6 weeks. Triacylglycerols, total cholesterol, HDLc, VLDLc and LDLc, in addition tests for hepatic and renal function and injury, were performed from serum obtained, and samples of liver,stomach, kidney and small intestine were collected for histological analysis. It was verified that the energy value of the portions of rations ingested did not differ amongst the three groups during the experimental period, however the animals submitted to the ketogenic diets had ingested a similar quantity of rations within the group, but less than (p=0.005) the control group. The ketogenic diet promoted similar weight gain amongst the group and only the animals in group KetoTAGC7 exhibited weight gain less than that of the control group (p=0.004) between the second and fifth weeks of the experiment. At the end of the study, all groups presented equivalent weights. There were no significant viii differences between the three groups as to the lipid profile, serum glucose and of the markers for hepatic function and injury. Histological analysis of samples from the small intestine, stomach and kidney did not show any significant morphological alteration and the presence of lipid infiltration within hepatocytes was detected in the same manner amongst the three groups. A ketogenic diet with a trienantin base did not promote toxic effects, under the conditions of this study, indicating the possibility that MCT could be administered to patients suffering neurological and metabolic defects, as part of ketogenic diet.
Fundação de Amparo a Pesquisa do Estado de Alagoas
A dieta cetogênica clássica, rica em triacilgliceróis de cadeia longa (TCL), é caracterizada por uma alta concentração de lipídeos e, ao mesmo tempo, por uma baixa concentração de carboidratos e proteínas para promover cetonemia/cetonúria, propriedade utilizada no tratamento de várias desordens que afetam o metabolismo e a função cerebral, a exemplo da epilepsia resistente ao uso de medicamentos. Os triacilgliceróis de cadeia média (TCM) são considerados um substrato alternativo aos TCL na elaboração desta dieta, por promoverem um aumento mais rápido nos níveis dos corpos cetônicos sanguíneos. A trienantina é um triacilglicerol de cadeia média do ácido graxo enântico (7:0), utilizada com sucesso em crianças portadoras de síndromes metabólicas herdadas, havendo poucos estudos sobre seus efeitos toxicológicos. A presente dissertação teve como objetivo avaliar a toxicidade do consumo subcrônico da dieta cetogênica à base de trienantina em ratos jovens, sendo desenvolvida na forma de dois artigos. No primeiro, denominado Substituição de TCL por TCM na terapia nutricional: uma ênfase no tratamento cetogênico, apresenta-se uma revisão sobre a dieta cetogênica, confrontando-se dados sobre os efeitos dos TCL e dos TCM, em experimentos animais e ensaios clínicos. A mais rápida cetonemia promovida pelos TCM permite utilizar uma menor quantidade de lipídios e maior de proteínas e de carboidratos, aumentando a palatabilidade da dieta. O efeito da substituição de TCL por TCM sobre parâmetros fisiológicos, como o perfil lipídico sérico, é controverso, necessitando-se de pesquisas adicionais para entendimento da repercussão dessa classe de lipídios sobre a saúde humana. O segundo artigo, intitulado Avaliação toxicológica subcrônica de dieta cetogênica à base de trienantina em ratos jovens, trata do estudo experimental realizado em ratos Wistar, em que foram estabelecidos 3 grupos (n=10), denominados, segundo a dieta recebida, em Controle (dieta padrão AIN-93G), CetoTAGC7 (cetogênico à base de trienantina; AIN-93G modificada para conter 4% de óleo de soja, 25,79% de trienantina e 40% de margarina) e CetoTAGsoja (cetogênico à base de soja; AIN-93G modificada para conter 29,79% de óleo de soja e 40% de margarina). A proporção lipídeos:carboidratos+proteína das dietas cetogênicas foi de 3,5:1 (dieta controle, 1:11,8) e o período experimental totalizou 6 semanas. Triacilgliceróis, colesterol total, HDLc, VLDLc e LDLc, além de provas de função e lesão hepática e renal, foram medidos nas amostras de soro obtidas e fragmentos de fígado, estômago, rim e intestino delgado foram coletados para a análise histológica. Verificou-se que o valor energético da cota de ração ingerida pelos três grupos, no período experimental, não foi diferente, embora os animais submetidos às dietas cetogênicas tenham ingerido uma quantidade de ração semelhante entre si, mas inferior (P<0,005) aos do grupo controle. As dietas cetogênicas promoveram ganho de peso vi semelhante entre si e apenas os animais do grupo CetoTAGC7 exibiram ganho de peso inferior (P=0,004) em relação aos do grupo controle, entre a 2ª e a 5ª semana de experimento. Ao final do estudo, todos os grupos apresentaram pesos equivalentes. Não houve diferenças significativas entre os três grupos quanto ao perfil lipídico e glicose séricos e aos marcadores de função e lesão hepática e renal. A análise histológica dos fragmentos de intestino delgado, estômago e rim não evidenciou qualquer alteração morfológica importante e a presença de infiltração lipídica nos hepatócitos foi detectada de maneira semelhante para os três grupos. A dieta cetogênica à base de trienantina não promoveu efeitos tóxicos, nas condições do presente estudo, indicando a possibilidade deste TCM ser administrado em pacientes portadores de desordens neurológicas e defeitos metabólicos, inclusive, em concentrações cetogênicas.

APA, Harvard, Vancouver, ISO, and other styles

44

Rêgo, Elisabete da Silva Mendonça. "Efeito de dieta cetogênica à base de óleo de coco sobre as crises convulsivas de ratos portadores de epilepsia induzida por pilocarpina." Universidade Federal de Alagoas, 2011. http://repositorio.ufal.br/handle/riufal/654.

Full text

Abstract:

Epilepsy is a chronic disturbance of brain function characterized by the presence of recurrent and spontaneous seizures, making one of the most frequent and severe neurological diseases, affecting approximately 50 million people worldwide, mainly children. Among these, 40% had antiepileptic drug refractory seizures. Non-drug options as surgery, vagus nerve stimulation and the ketogenic diet are timely. This diet, used since 1921 in treatment of drug-resistant epilepsy is characterized by a high concentration of lipids and often by low concentration of carbohydrates and proteins. Traditionally, the ketogenic diet use long chain triacylglycerols (LCT), however, the medium chain triacylglycerols (MCT) are considered an alternative substrate for promoting faster ketonemia-ketonuria. The oil from coconut (Cocos nucifera L.) is a natural source of MCT, and is used for several purposes, including therapeutic. This dissertation aims to investigate the effects of the ketogenic diet based on coconut oil and soybean oil on epileptic seizures in rats, consists of a review chapter, entitled Drug-resistant epilepsies: an emphasis on treatment ketogenic, and an article from the results, entitled Effects of ketogenic diet based on coconut oil on the seizures of rats with epilepsy induced by pilocarpine. The article deals an experimental study conducted in Wistar rats, divided into three groups (n=10), named according to the diet received, in Control (standard diet AIN-93G), CetoTAGcoco (ketogenic diet based in coconut oil; AIN-93G diet modified to contain 7% soybean oil, 22.79% of extra virgin coconut oil and 40% margarine) and CetoTAGsoja (ketogenic diet based in soybean oil; AIN-93G diet modified to contain 29.79% of soybean oil and 40% margarine). The ratio lipid:carbohydrate+protein of ketogenic diets was 3.5:1 (control diet, 1:11.8). The experimental period lasted 19 days. The animals fed ketogenic diets showed food intake (g) below, however, dispend energetic and weight gain similar to Control group. The behavioral analysis showed that the experimental groups did not differ in frequency and duration of seizures, however, the animals in group CetoTAGcoco had shorter duration of seizures in the 19th day, that the Control group (0.00±0.00 against 22.78±2.95, respectively, P<0.05). Additionally, the CetoTAGcoco group presented lower variation of frequency and duration of seizures between the 19th and 1st day of treatment than the Control group (9.00±1.73 against 11.00±1.00, for frequency, and 20.80±12.61 against 49.14±21.15, for duration, respectively, P<0.05). The results of this study suggest a possible protective effect of ketogenic diet based on extra virgin coconut oil on seizures. That result, coupled with studies attesting to confidence and tolerance of the coconut oil, particularly in ketogenic ratios, indicating a potential benefit of this oil for control the seizures, especially for individuals with medically refractory epilepsy.
Fundação de Amparo a Pesquisa do Estado de Alagoas
A epilepsia é um disturbio crônico da função cerebral, caracterizado pela presença de crises convulsivas recorrentes e espontâneas. Trata-se de uma das mais frequentes e graves doenças neurológicas, que afeta cerca de 50 milhões de pessoas no mundo, principalmente crianças. Dentre estas, 40% apresentam crises refratárias às drogas antiepilépticas existentes. Opções não farmacológicas, como cirurgia, estimulação do nervo vago e dieta cetogênica, são oportunas. Esta dieta, utilizada desde 1921 no tratamento da epilepsia fármaco-resistente, caracteriza-se por alta concentração de lipídeos e, frequentemente, por baixa concentração de carboidratos e proteínas. Tradicionalmente, a dieta cetogênica utiliza como fonte lipídica os triacilgliceróis de cadeia longa (TCL); porém, os triacilgliceróis de cadeia média (TCM) são considerados um substrato alternativo, por promoverem cetonemia/cetonúria de forma mais rápida. O óleo proveniente do coco (Cocos nucifera L.) representa uma fonte natural de TCM, sendo utilizado para diversos fins, inclusive terapêuticos. A presente dissertação visa investigar os efeitos de dieta cetogênica à base de óleo de coco e óleo de soja sobre as crises convulsivas de ratos epilépticos. É constituída por um capítulo de revisão, intitulado Epilepsias fármaco-resistentes: uma ênfase no tratamento cetogênico, e um artigo de resultados, intitulado Efeito de dieta cetogênica à base de óleo de coco sobre as crises convulsivas de ratos portadores de epilepsia induzida por pilocarpina. O artigo trata de um estudo experimental realizado com ratos Wistar, alocados em três grupos (n=10), denominados, segundo a dieta recebida, em Controle (dieta padrão AIN-93G), CetoTAGcoco (dieta cetogênica à base de óleo de coco; AIN-93G modificada, com 7% de óleo de soja, 22,79% de óleo de coco extra-virgem e 40% de margarina) e CetoTAGsoja (dieta cetogênica à base de óleo de soja; AIN-93G modificada, com 29,79% de óleo de soja e 40% de margarina). A proporção lipídeos: carboidratos+proteína das dietas cetogênicas foi de 3,5:1 (dieta controle, 1:11,8). O período experimental totalizou 19 dias. Os animais submetidos aos tratamentos cetogênicos apresentaram consumo alimentar (g) inferior, porém, consumo energético (Kcal) e ganho de peso corporal (g) semelhantes ao grupo Controle. As análises comportamentais demonstraram que os animais dos grupos experimentais não diferiram entre si quanto à freqüência e à duração total das crises; entretanto, os animais do grupo CetoTAGCcoco tiveram menor duração média de crises no 19º dia, que o grupo Controle (0,00±0,00 contra 22,78±12,95, respectivamente; p<0,05). Adicionalmente, o grupo CetoTAGcoco apresentou valores inferiores de variação de frequência e de duração das crises entre o 19° e o 1° dia de tratamento, que o grupo Controle (9,00±1,73 contra 11,00±1,00, para freqüência, e 20,80±12,61 contra 49,14±21,15, para duração, respectivamente; p<0,05). Os resultados do presente estudo apontam para um possível efeito protetor da dieta cetogênica à base de óleo de coco extra-virgem sobre as crises convulsivas. Tais resultados, associados a estudos que atestem a confiabilidade e a tolerância do consumo de óleo de coco, particularmente em proporções cetogênicas, poderiam indicar um benefício potencial deste óleo no controle das crises convulsivas, especialmente para indivíduos portadores de epilepsia refratária a medicamentos.

APA, Harvard, Vancouver, ISO, and other styles

45

Mason, Susan Leigh. "Metabolism of triacylglycerol-rich lipoproteins in sheep." Lincoln University, 1991. http://hdl.handle.net/10182/1756.

Full text

Abstract:

This thesis describes two approaches for studying of lipoprotein metabolism in sheep. The first approach involves the assay of lipoprotein lipase (LPL) activity to determine the role of lipoprotein-triacylglycerol fatty acids in fat deposition in sheep. This enzyme is the rate limiting enzyme in the hydrolysis of fatty acids from lipoprotein-triacylglycerol. The second approach was to characterize and quantify in vivo lipoprotein metabolism using iodinated very low density lipoprotein (¹²⁵I-VLDL) and low density lipoprotein (¹³¹I-LDL). Cross-bred lambs were divided into two treatment groups and either weaned early at 5 weeks of age or remained suckling. Lambs were slaughtered at 12 or 23 weeks at which time the body composition and adipose tissue LPL activity were determined. The differences in rearing led to differences in body composition. The suckled lambs were larger and fatter than weaned lambs. The increased fatness in the suckled lambs was associated with increased LPL activity (U/mg protein) in subcutaneous adipose tissue and was reflected in higher LPL activity in post-heparin plasma (PHP) taken 2 days prior to slaughter. The role of insulin in the regulation of LPL activity was investigated by either infusing a subset of the weaned and suckled lambs with insulin for 7 or 18 weeks or using the euglycemic clamp technique to study the effect of short insulin infusions. The long term infusion of insulin had no significant effect on PHP LPL or on adipose tissue LPL (U/g tissue). However, after infusing insulin for 6h at 6.3 mU.kg⁻·⁷⁵.h⁻¹ during the euglycemic clamps, a two fold increase in LPL activity in biopsied subcutaneous adipose tissue was observed. In the second approach, in vivo lipoprotein metabolism was investigated in 4 lambs using apolipoprotein B as a marker. Following the simultaneous injection of ¹²⁵I VLDL and ¹³¹I VLDL, the specific activities of apoB in VLDL, IDL and LDL fractions were determined. ApoB specific activity curves demonstrated that VLDL is metabolised to IDL and subsequently to LDL. The turnover of VLDL-B (3.45mg.d⁻¹.kg⁻¹) and LDL-B (4.8mg.d⁻¹.kg⁻¹) was calculated by fitting the VLDL-¹²⁵I-B and LDL-¹³¹I-B specific activity data to a mono-exponential equation. The metabolism of lipoproteins, inferred from the study of apoB, was shown to be similar in sheep to that reported in other animals although the amount of lipoprotein synthesised was low. A model to describe the kinetics of apoB metabolism in sheep was developed using SAAM. The proposed model features a three pool delipidation chain for VLDL, and subsystems containing two pools for IDL and LDL. IDL may be catabolised to LDL or cleared directly from the plasma. The developed model can now be used to compare the metabolism of lipoproteins in different physiological states and to design new experiments to study lipoprotein metabolism further.

APA, Harvard, Vancouver, ISO, and other styles

46

Santiago, Heber Peleg Cornelio. "Medida da solubilidade de óleo de café verde (Coffea arabica L.) em dióxido de carbono supercrítico e modelagem termodinâmica." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/74/74132/tde-05102015-101828/.

Full text

Abstract:

O objetivo do presente estudo foi medir experimentalmente a solubilidade do óleo de café verde em dióxido de carbono supercrítico em condições preestabelecidas de pressão (P) e temperatura (T), e a partir dos dados experimentais estabelecer ajustes em modelos termodinâmicos que empregam a equação de estado (EDE) de Peng-Robinson com a regra de mistura clássica de van der Waals para predição do equilíbrio de fases. Foi obtido óleo a partir de grãos de café verde (Coffea arabica), cultivar (cv.) Catuaí Amarelo moído (dm de 0,8409 mm) usando CO2 supercrítico, nas condições de 40, 50, 60, 70, 80 °C e nas pressões de 300 e 350 bar. A solubilidade foi medida pelos métodos dinâmico e estático nas mesmas condições. Foi determinado o perfil de ácidos graxos por cromatografia gasosa acoplada à espectrometria de massas (CG/EM) e, a partir destes resultados, a composição em triacilgliceróis (TAGs) foi estimada. Foram determinadas as propriedades físico-químicas dos TAGs pelo método de contribuição de grupos. Nas condições de P e T estudadas, os maiores rendimentos do óleo de grãos de café verde, 7,58% e 7,60%, foram obtidos nas condições de 70 °C e 300 bar e 80 °C e 350 bar, respectivamente. Normalmente o rendimento do óleo aumentou com o aumento da temperatura, com exceção das condições de 80 °C e 300 bar e 70 °C e 350 bar. O aumento do rendimento com a temperatura reflete nos dados experimentais da solubilidade (0,0099 a 0,026 g/gCO2) que aumentou com a temperatura a 300 e 350 bar para o método estático e para o método dinâmico a 350 bar (0,0058 a 0,0065 g/gCO2). Um comportamento distinto ocorreu com a medida de solubilidade pelo método dinâmico a 300 bar. Neste caso a solubilidade diminuiu com o aumento da temperatura. Para a maioria das condições de P e T estudadas, o comportamento da solubilidade foi semelhante em função destas variáveis, o mesmo para os métodos estático e dinâmico, no entanto com ordens de grandezas distintas. As condições de extração não influenciaram na composição dos ácidos graxos no óleo nem na predição dos TAGs presentes. Os TAGs apresentaram variações entre número de carbonos (C50 a C58). As propriedades físico-químicas dos seis principais TAGs presentes no óleo de grãos de café verde (PSL, PLL, PLP, PLO, PLA e POP), temperatura do ponto de ebulição normal (Tb), temperatura crítica (Tc), pressão crítica (Pc) e fator acêntrico (ω) foram estimadas por métodos de contribuição de grupos. Estas variáveis são dados de entrada para a predição do equilíbrio de fases entre o óleo de grãos de café verde, representado pela mistura dos seis TAGs em maior concentração neste óleo, e o CO2 supercrítico. Os valores de Tb dos TAGs variaram de 821,52 a 844,50 K, os valores de Tc de 909,12 a 930,02 K, os valores de Pc de 5,0115 a 4,7221 bar e o ω de 1,5704 a 1,7452. Os dados de propriedades físicas e da solubilidade convertida em fração molar foram usados para predizer os parâmetros de interação binária da regra de mistura clássica de van der Waals entre cada TAG e o CO2 supercrítico, já que estes parâmetros também são dados de entrada para a modelagem termodinâmica que emprega a EDE de Peng-Robinson. No entanto, o programa não rodou, não sendo possível este cálculo, nem tão pouco a predição do equilíbrio de fases. Os dados experimentais da solubilidade do óleo de grãos de café verde em CO2 supercrítico determinados pelos métodos estático e dinâmico indicou que àqueles determinados pelo método estático são mais precisos e confiáveis.
The objective of this study was to experimentally measure the solubility of green coffee oil in supercritical carbon dioxide under predetermined pressure (P) and temperature (T) conditions and, from the experimental data, establish thermodynamic models that use the Peng-Robinson equation of state (EOS) and the classic mixing rule of van der Waals to predict phase equilibrium. The oil was obtained from ground green coffee beans (Coffea arabica L.) cultivar (cv.) Yellow Catuaí (dm of 0.8409 mm) using supercritical CO2 under temperatures of 40, 50, 60, 70 and 80 °C and pressures of 300 and 350 bar. The solubility was measured by dynamic and static methods under the same conditions. The fatty acid profile was determined by gas chromatography-mass spectrometry (GC/MS) and, from these results, the composition of triacylglycerols (TAGs) was estimated. Physicochemical properties of TAGs were determined by the group contribution method. In the studied conditions of P and T, higher yields of green coffee beans oil, 7.58% and 7.60%, were obtained at 70 °C and 300 bar and 80 °C and 350 bar, respectively. Normally, the oil yield increased with increasing temperatures, except for the conditions of 80 °C and 300 bar and 70 °C and 350 bar. The increase of yield with temperature reflects in the experimental solubility data (from 0.0099 to 0.026 g/g CO2), which, also increased with T at 300 and 350 bar for the static method and, for the dynamic method, at 350 bar (from 0.0058 to 0.0065 g/g CO2). A different behavior occurred with the solubility measured by dynamic method at 300 bar. In this case, the solubility decreased with increasing temperature. For most of the P and T conditions studied, the solubility behavior was similar in function of these variables, the same for static and dynamic methods, but with different magnitude orders. The extraction conditions did not affect the composition of fatty acids in the oil and nor the TAGs prediction. The TAGs showed variations between carbon numbers (from C50 to C58). The physicochemical properties of the six major TAGs present in green coffee bean oil (PSL, PLL, PLP, PLO, PLA and POP), boiling temperature (Tb), critical temperature (Tc), critical pressure (Pc) and acentric factor (ω) were estimated by group contribution methods. These are input variables for the prediction for the phase equilibrium between the green coffee oil, represented by the mixture of the six TAGs in higher concentration in this oil, and supercritical CO2. The Tb values of TAG ranged from 821.52 to 844.50 K, Tc values from 909.12 to 930.02 K, Pc values from 5.0115 to 4.7221 bar and ω from 1, 5704 to 1.7452. The data of physical properties and solubility converted to mole fraction were used to predict the binary interaction parameters of the classic mixing rule of van der Waals between each TAG and supercritical CO2, since these are also input parameters for the thermodynamic modeling that use Peng-Robinson EOS. However, the program did not run and this calculation was not possible, nor the prediction for the phase equilibrium. The experimental data on the solubility of the green coffee beans oil in supercritical CO2 determined by static and dynamic methods indicated that those determined by the static method are more accurate and reliable.

APA, Harvard, Vancouver, ISO, and other styles

47

Diaz, Salazar Albelda Carlos. "Redundancy in the biosynthesis of triacylglycerol by Rhodococcus." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58982.

Full text

Abstract:

Many mycolic acid-containing actinobacteria are oleaginous, accumulating high amounts of triacylglycerols (TAGs) under conditions of nutrient stress. These bacteria contain multiple copies of the genes involved in TAG biosynthesis: glycerol-phosphate acyltransferase (GPAT), acylglycerol-phosphate acyltransferase (AGPAT), phosphatidic acid phosphatase (PAP) and diglyceride acyltransferases (WS/DGAT), encoded by plsB, plsC, pap, and atf, respectively. Analysis of Rhodococcus jostii RHA1’s genome revealed that it carries 1 plsB, 8 plsC, 7 pap, and 16 atf. Quantitative, time-dependent data of six of these atf genes, selected based on previous transcriptomics data, revealed distinct expression patterns under nitrogen-limiting (N-) and carbon-limiting (C-) conditions. For example, the levels of atf10, atf3 and atf8 transcripts dropped ~10-fold upon growth substrate depletion, while the levels of atf4, atf6 and atf9 transcripts rose. Under N- conditions, RHA1 cells continued to accumulate TAGs for five days after ammonia depletion, during which time atf10 and atf8 transcripts remained abundant. Targeted deletion of any one of atf3, atf4, atf6, atf9 and atf10 did not significantly affect TAG accumulation under N- conditions, consistent with the redundancy of putative acyltransferases in the RHA1 genome. However, deletion of both atf8 and atf10 resulted in a 50% decrease in TAG accumulation. Furthermore, the fatty acid profile of the ∆atf8∆atf10 mutant was significantly perturbed, and was restored by complementation with either atf8 or atf10. RT-qPCR data analysis also revealed that the expression patterns of plsC (RS27555) and plsB were the same as that of atf9, consistent with their occurrence in an operon. Unexpectedly, deletion of plsB did not affect TAG accumulation, suggesting an alternative pathway for TAG and phospholipids biosynthesis. Finally, I identified three genes encoding HAD-type hydrolases as being putatively involved in TAG biosynthesis, including one that occurs as a fusion with plsC. The available data suggest that they act as PAPs. Overall, the results establish that there is a certain degree of functional redundancy in TAG biosynthesis, and that Atf8 and Atf10 play a major role in TAG accumulation. At the same time, the results also highlight important gaps in our knowledge of TAG biosynthesis in mycolic acid-containing oleaginous actinobacteria.
Science, Faculty of
Graduate

APA, Harvard, Vancouver, ISO, and other styles

48

Wilfling, Florian. "The spatial organization and regulation of triacylglycerol synthesis." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-170796.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Griffiths, G. "Aspects of triacylglycerol biosynthesis in developing oil-seeds." Thesis, University of Bristol, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372041.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Dabbs, Parker, Carlee Haas, and Aruna Kilaru. "Transcriptional Regulators of Triacylglycerol Biosynthesis in Nonseed Tissues." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/4859.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Triacylglycerols'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles