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Effects of Free Fatty Acids, Mono- and Diacylglycerols on Oxidative Stability of Soybean Oil-In-Water EmulsionsWaraho, Thaddao 13 May 2011 (has links)
Even though edible oils undergo refining processes to remove undesirable components, commercial oils still contain small amounts of minor components that can contribute to either prooxidant and antioxidant pathways which ultimately affect the quality of the oils. The objective of this research was to determine the role of free fatty acids and mono- and diacylglycerols on the oxidative stability of oil-in-water emulsions.
Free fatty acids acted as a strong prooxidants in stripped soybean oil-in-water emulsions. Concentrations as low as 0.1% of the lipid accelerated lipid oxidation rate by both shortening the lag phase of lipid hydroperoxide and hexanal formation. The results showed that the most likely mechanisms for the prooxidant activity of free fatty acids is through their ability to increase the negatively charge on emulsion droplets that in turn could attract the cationic transition metals to the emulsion droplet surface where they can interact with lipid and thus promote oxidation. The prooxidant activity of free fatty acids was dependent on fatty acid type with lipid oxidation rates being in the order of linolenic < linoleic < oleic. Surprisingly, an increase in the degree of unsaturation of the free fatty viii acids lowered the ability of the free fatty acids to promote oxidation which may be due to their differences in geometric shape thus influencing their ability to access the emulsion droplet interface and increase the negative charge. Overall, free fatty acids are strong prooxidants in oil-in-water emulsions. This prooxidant activity is dependent not only on their concentration but also on the molecular structure of the fatty acid.
Addition of mono- and diacylglycerols in oil-in-water emulsions showed an antioxidative effect in both non-stripped and stripped soybean oil. Addition of 1-monooleoylglycerol only had a small impact on the oxidative stability of non-stripped soybean oil-in-water emulsions but did inhibit lipid oxidation in emulsions prepared with stripped soybean. Much stronger antioxidant activity was observed upon the addition of 1,2-dioleoyl-sn-glycerol to both non-stripped and stripped soybean oil-in-water emulsions. Both lipid hydroperoxide and hexanal formation decreased with increasing 1,2-dioleoyl-sn-glycerol concentrations with 2.5% 1,2-dioleoyl-sn-glycerol almost completely preventing hydroperoxide and hexanal production over the course of the study. Overall, these results suggest that diacylglycerols could be an effective antioxidant in oil-in-water emulsions which possibility due to their ability to form a liquid crystal phase which could form a physical barrier that decreases interactions between unsaturated fatty acids in the emulsion droplet core and prooxidants or oxygen in the aqueous phase of the emulsion. However, the antioxidant mechanism of diacylglycerols is not currently understood and needs further investigation.
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Rôle d’ABHD6 dans l’agressivité et la progression du cancer de la prostateLanglois, Patricia 04 1900 (has links)
Les cellules tumorales présentent des altérations de leur métabolisme, notamment le développement d'un phénotype lipogénique incluant l’augmentation de l’expression de protéines de la lipolyse. L'α/β-hydrolase domaine-6 (ABHD6), par son rôle dans l'hydrolyse des monoacylglycérols, semble être un acteur important dans le réseau lipidique de signalisation protumorigène. Des études ont révélé qu’ABHD6 est surexprimée dans l'ostéosarcome et la lignée cellulaire PC-3 du cancer de la prostate (CP), ainsi que dans les tumeurs d'Ewing. La suppression de l'expression d’ABHD6 a réduit la croissance du cancer du poumon et de ses métastases chez les souris. Ainsi, ABHD6 pourrait être un lien important entre la lipolyse et la progression du cancer. Nous émettons l'hypothèse que l'inhibition d'ABHD6 freinerait la prolifération, la migration et l’invasion des cellules du CP.
Les résultats montrent que l'expression d’ABHD6 est plus élevée dans les lignées LNCaP et C4-2B que dans les lignées les plus agressives (DU145 et PC-3). L’inhibition d'ABHD6 par le KT203 a réduit la prolifération des cellules du CP avec une sensibilité plus marquée dans les LNCaP et PC-3. La perte d’expression d’ABHD6 via un pARNi affecte de façon prononcée la prolifération de l’ensemble des lignées. La migration et l'invasion des cellules PC-3 ont été notablement réduites de plus de 50 % en présence de KT203, mais cet inhibiteur n'a eu que peu d'impact sur les cellules 22Rv1 ou C4-2B. L'inhibition d'ABHD6 semble inverser l'expression des marqueurs EMT dans les cellules PC3. Ces résultats suggèrent que ABHD6 pourrait jouer un rôle dans la progression du CP. / Tumor cells alter their metabolism to adapt to increased proliferation and survival under restricted nutrient availability. These metabolic changes include accelerated glycerolipid/ fatty acid cycle that encompasses lipogenesis and lipolysis. The lipolytic enzyme a/b-hydrolase domain-6 (ABHD6), which hydrolyzes monoacylglycerols, could be a potential player in the pro- tumorigenic lipid signaling network that promotes migration, survival, and growth of cancer cells. ABHD6 is found to be elevated in several cancers including prostate cancer (PC) cell-lines. Suppression of ABHD6 expression was shown to reduce lung cancer growth and metastases in mice. The possibility that ABHD6 could be an important link between lipolysis and cancer progression is not investigated in detail. We hypothesize that ABHD6 inhibition would curtail PC cell proliferation, migration and invasion capabilities. ABHD6 expression was assessed in 22Rv1, LNCaP, C4-2B, DU145, and PC-3 PC cell-lines. The impact of ABHD6 suppression either by RNAi- knockdown or by a specific inhibitor, KT203, on PC cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) was examined.
Our results show that ABHD6 expression was relatively higher in LNCaP and C4-2B, as compared to the more aggressive PC cell-lines (DU145 and PC-3). ABHD6 inhibition by KT203 reduced PC cell proliferation, more markedly in LNCaP and PC-3. However, RNAi-knockdown of ABHD6 equally reduced the proliferation of all PC cell-lines. Migration and invasion of PC-3 cells was notably decreased by more than 50% by KT203 whereas there was less effect on 22Rv1 or C4-2B cells. ABHD6 inhibition appears to reverse the expression of EMT markers in the PC-3 cells. These findings suggest that ABHD6 inhibition may prevent progression of aggressive prostate cancer.
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Conversão enzimática de triacilgliceróis em mono e diacilgliceróis de interesse industrial / Enzymatic conversion of triacylglycerols to mono and diacilglycerols of industrial interestSylvio Jorge Hares Junior 27 October 2017 (has links)
Mono e diacilgliceróis são produtos empregados na indústria alimentícia, farmacêutica, cosmética e química como emulsificantes e melhoradores de viscosidade de produtos alimentícios, cosméticos e farmacêuticos. No entanto, a forma mais usual de obtê-los é por síntese química, o que acaba rendendo produtos finais caros e com atributos de qualidade, rendimento e de aplicabilidade tecnológica inferiores aos esperados. A busca por formas de obtenção mais racionais, eficientes e com melhor padrão de qualidade destes produtos foi o objetivo principal do trabalho, por meio de hidrólise parcial enzimática, que necessita de condições de reação mais brandas. Foram avaliadas a hidrólise enzimática descontína, empregando como substrato a trioleína técnica, e a hidrólise enzimática descontínua-alimentada, usando como substrato o óleo de girassol médio oléico. Foi utilizada, em ambos processsos, a lipase imobilizada sn-1,3 específica Lipozyme RM IM (de Rhizomucor miehei). A caracterização dos padrões e dos substrados, bem como o acompanhamento da formação dos produtos da hidrólise enzimática foram feitos por determinação da porcentagem de hidrólise, cromatografia em camada delgada (TLC), dos perfis das curvas de fusão e cristalização por calorimetria diferencial de varredura (DSC), cromatografia gasosa (CG) e cromatografia de exclusão de tamanho de alto desempenho (HPSEC). Os parâmetros de hidrólise descontínua foram o tempo de reação, a temperatura e a concentração inicial de substrato. Os parâmetros de hidrólise descontínua-alimentada foram tempo de enchimento e intervalo de alimentação de substrato. Para as respostas analíticas de porcentagem de hidrólise e de composição de frações lipídicas foi aplicado um modelo de regressão múltipla com base em metodologia de superfície de resposta. Os resultados experimentais observados nas reações de hidrólise enzimática descontínua de trioleína técnica mostraram de 24,7 a 34,2% de mono e diacilgliceróis (para 5% de óleo na emulsão) e de 21,4 a 33,6% de mono e diacilgliceróis (para 20% de óleo na emulsão). Os resultados experimentais observados nas reações de hidrólise enzimática descontínua-alimentada de óleo de girassol médio oléico (para 15% de óleo na emulsão), mostraram de 7,9 a 31,8% de mono e diacilgliceróis. Os modelos de superfície de resposta foram considerados significativos e preditivos. As hidrólises obtidas no formato descontínuo e descontínuo-alimentado permitiram efetivamente a obtenção de frações de mono/ diacilgliceróis com vários graus de eficiência de conversão e com corretas identificação e quantificação das frações de lipídios procuradas. As correlações feitas entre porcentagem de hidrólise e entalpias de cristalização e fusão, corroboradas com os resultados qualitativos e/ou quantitativos diretos obtidos na cromatografia de camada delgada (TLC) e de HPSEC, demonstraram que estes atributos podem positivamente indicar a ocorrência efetiva de reação de hidrólise, além de auferir uma escala de desempenho de reação alinhada com o previsto na literatura, à medida que são aumentadas a temperatura, o tempo de hidrólise e a porcentagem inicial de substrato oleoso, sob regime descontínuo, e que puderam ser melhoradas, de forma inovadora, sob parâmetros de tempo total de alimentação e de intervalo de alimentação, sob regime descontínuo-alimentado. A hidrólise parcial enzimática de triacilgliceróis utilizando lipase imobilizada sn-1,3 específica pode ser considerada uma alternativa às vias químicas para a produção de misturas de mono e diacilgliceróis para utilização como aditivos químicos. / Mono and diacylglycerols are products used in the food, pharmaceutical, cosmetic and chemical industries as emulsifiers and viscosity improvers for food products, cosmetics and pharmaceuticals. However, the most usual forms of obtaining them are by chemical synthesis, which ends up yielding expensive final products with attributes of quality, yield and technological applicability lower than expected. The search for more rational, efficient and better quality standards of these products was the aim of the work, through partial enzymatic hydrolysis, which requires milder reaction conditions. Discontinuous enzymatic hydrolysis was evaluated using technical triolein as substrate and discontinuous-fed enzymatic hydrolysis using as the substrate the mid oleic sunflower oil. In both processes, immobilized lipase sn-1,3 specific Lipozyme RM IM (from Rhizomucor miehei) was used. The characterization of the patterns and substrates, as well as the monitoring of the formation of the products from the enzymatic hydrolysis were made by determining the percentage of hydrolysis, thin layer chromatography (TLC), profiles of the melting and crystallization curves by differential scanning calorimetry ( DSC), gas chromatography (GC) and high performance size exclusion chromatography (HPSEC). The parameters of discontinuous hydrolysis were the reaction time, the temperature and the initial substrate concentration. The parameters of discontinuous-fed hydrolysis were filling time and substrate feed interval. For the analytical responses of hydrolysis percentage and composition of lipid fractions a multiple regression model was applied based on response surface methodology. The experimental results observed in the reactions of discontinuous enzymatic hydrolysis of technical triolein indicated amounts of mono- and diacylglycerols from 24.7 to 34.2% (for 5% of oil in the emulsion) and from 21.4 to 33.6% for mono and diacylglycerols with 20% oil in the emulsion. The experimental results observed in the reactions of discontinuous-fed enzymatic hydrolysis of mid oleic sunflower oil (for 15% oil in the emulsion), showed from 7.9 to 31.8% of mono and diacylglycerols. Response surface models were considered significant and viii predictive. The hydrolysis obtained in the discontinuous and discontinuous-fed form allowed to obtain fractions of mono / diacylglycerols with various degrees of conversion efficiency and with correct identification and quantification of the lipid fractions sought. The correlations between the percentage of hydrolysis and enthalpies of crystallization and fusion, corroborated with the qualitative and / or quantitative direct results obtained in thin layer chromatography (TLC) and HPSEC, showed that these attributes can positively indicate the effective occurrence of reaction of Hydrolysis, in addition to achieving a reaction performance scale in line with the literature, as the temperature rate, the hydrolysis time and the initial percentage of oily substrate are increased under a discontinuous regime and can be improved, in a innovative form, under parameters of total filling time and feeding interval, under a fed-batch regime. The partial enzymatic hydrolysis of triacylglycerols using specific sn-1,3-specific immobilized lipase may be considered an alternative to the chemical pathways for the production of mono- and diacylglycerol blends for use as chemical additives.
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Conversão enzimática de triacilgliceróis em mono e diacilgliceróis de interesse industrial / Enzymatic conversion of triacylglycerols to mono and diacilglycerols of industrial interestHares Junior, Sylvio Jorge 27 October 2017 (has links)
Mono e diacilgliceróis são produtos empregados na indústria alimentícia, farmacêutica, cosmética e química como emulsificantes e melhoradores de viscosidade de produtos alimentícios, cosméticos e farmacêuticos. No entanto, a forma mais usual de obtê-los é por síntese química, o que acaba rendendo produtos finais caros e com atributos de qualidade, rendimento e de aplicabilidade tecnológica inferiores aos esperados. A busca por formas de obtenção mais racionais, eficientes e com melhor padrão de qualidade destes produtos foi o objetivo principal do trabalho, por meio de hidrólise parcial enzimática, que necessita de condições de reação mais brandas. Foram avaliadas a hidrólise enzimática descontína, empregando como substrato a trioleína técnica, e a hidrólise enzimática descontínua-alimentada, usando como substrato o óleo de girassol médio oléico. Foi utilizada, em ambos processsos, a lipase imobilizada sn-1,3 específica Lipozyme RM IM (de Rhizomucor miehei). A caracterização dos padrões e dos substrados, bem como o acompanhamento da formação dos produtos da hidrólise enzimática foram feitos por determinação da porcentagem de hidrólise, cromatografia em camada delgada (TLC), dos perfis das curvas de fusão e cristalização por calorimetria diferencial de varredura (DSC), cromatografia gasosa (CG) e cromatografia de exclusão de tamanho de alto desempenho (HPSEC). Os parâmetros de hidrólise descontínua foram o tempo de reação, a temperatura e a concentração inicial de substrato. Os parâmetros de hidrólise descontínua-alimentada foram tempo de enchimento e intervalo de alimentação de substrato. Para as respostas analíticas de porcentagem de hidrólise e de composição de frações lipídicas foi aplicado um modelo de regressão múltipla com base em metodologia de superfície de resposta. Os resultados experimentais observados nas reações de hidrólise enzimática descontínua de trioleína técnica mostraram de 24,7 a 34,2% de mono e diacilgliceróis (para 5% de óleo na emulsão) e de 21,4 a 33,6% de mono e diacilgliceróis (para 20% de óleo na emulsão). Os resultados experimentais observados nas reações de hidrólise enzimática descontínua-alimentada de óleo de girassol médio oléico (para 15% de óleo na emulsão), mostraram de 7,9 a 31,8% de mono e diacilgliceróis. Os modelos de superfície de resposta foram considerados significativos e preditivos. As hidrólises obtidas no formato descontínuo e descontínuo-alimentado permitiram efetivamente a obtenção de frações de mono/ diacilgliceróis com vários graus de eficiência de conversão e com corretas identificação e quantificação das frações de lipídios procuradas. As correlações feitas entre porcentagem de hidrólise e entalpias de cristalização e fusão, corroboradas com os resultados qualitativos e/ou quantitativos diretos obtidos na cromatografia de camada delgada (TLC) e de HPSEC, demonstraram que estes atributos podem positivamente indicar a ocorrência efetiva de reação de hidrólise, além de auferir uma escala de desempenho de reação alinhada com o previsto na literatura, à medida que são aumentadas a temperatura, o tempo de hidrólise e a porcentagem inicial de substrato oleoso, sob regime descontínuo, e que puderam ser melhoradas, de forma inovadora, sob parâmetros de tempo total de alimentação e de intervalo de alimentação, sob regime descontínuo-alimentado. A hidrólise parcial enzimática de triacilgliceróis utilizando lipase imobilizada sn-1,3 específica pode ser considerada uma alternativa às vias químicas para a produção de misturas de mono e diacilgliceróis para utilização como aditivos químicos. / Mono and diacylglycerols are products used in the food, pharmaceutical, cosmetic and chemical industries as emulsifiers and viscosity improvers for food products, cosmetics and pharmaceuticals. However, the most usual forms of obtaining them are by chemical synthesis, which ends up yielding expensive final products with attributes of quality, yield and technological applicability lower than expected. The search for more rational, efficient and better quality standards of these products was the aim of the work, through partial enzymatic hydrolysis, which requires milder reaction conditions. Discontinuous enzymatic hydrolysis was evaluated using technical triolein as substrate and discontinuous-fed enzymatic hydrolysis using as the substrate the mid oleic sunflower oil. In both processes, immobilized lipase sn-1,3 specific Lipozyme RM IM (from Rhizomucor miehei) was used. The characterization of the patterns and substrates, as well as the monitoring of the formation of the products from the enzymatic hydrolysis were made by determining the percentage of hydrolysis, thin layer chromatography (TLC), profiles of the melting and crystallization curves by differential scanning calorimetry ( DSC), gas chromatography (GC) and high performance size exclusion chromatography (HPSEC). The parameters of discontinuous hydrolysis were the reaction time, the temperature and the initial substrate concentration. The parameters of discontinuous-fed hydrolysis were filling time and substrate feed interval. For the analytical responses of hydrolysis percentage and composition of lipid fractions a multiple regression model was applied based on response surface methodology. The experimental results observed in the reactions of discontinuous enzymatic hydrolysis of technical triolein indicated amounts of mono- and diacylglycerols from 24.7 to 34.2% (for 5% of oil in the emulsion) and from 21.4 to 33.6% for mono and diacylglycerols with 20% oil in the emulsion. The experimental results observed in the reactions of discontinuous-fed enzymatic hydrolysis of mid oleic sunflower oil (for 15% oil in the emulsion), showed from 7.9 to 31.8% of mono and diacylglycerols. Response surface models were considered significant and viii predictive. The hydrolysis obtained in the discontinuous and discontinuous-fed form allowed to obtain fractions of mono / diacylglycerols with various degrees of conversion efficiency and with correct identification and quantification of the lipid fractions sought. The correlations between the percentage of hydrolysis and enthalpies of crystallization and fusion, corroborated with the qualitative and / or quantitative direct results obtained in thin layer chromatography (TLC) and HPSEC, showed that these attributes can positively indicate the effective occurrence of reaction of Hydrolysis, in addition to achieving a reaction performance scale in line with the literature, as the temperature rate, the hydrolysis time and the initial percentage of oily substrate are increased under a discontinuous regime and can be improved, in a innovative form, under parameters of total filling time and feeding interval, under a fed-batch regime. The partial enzymatic hydrolysis of triacylglycerols using specific sn-1,3-specific immobilized lipase may be considered an alternative to the chemical pathways for the production of mono- and diacylglycerol blends for use as chemical additives.
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Síntese promovida por irradiação de micro-ondas de novos adutos de Morita-Baylis-Hillman hidrossolúveis com potencial atividade antiparasitária : um propostapara o uso do glicerol / Microwave-promoted synthesis of new water soluble Morita-Baylis- Hillman adducts with potential biological activity: a proposal for the use of glycerol.Sousa, Suervy Canuto de Oliveira 30 March 2011 (has links)
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Previous issue date: 2011-03-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study was conducted in order to develop the synthesis of new
Morita-Baylis-Hillman adducts of (MBHA) water soluble (29-34) with
potential parasitic activity, using glycerol (1) as raw material. Two
synthetic routes were carried out producing twelve new MBHA (23 - 34),
six of which have hydrophilic characteristics 29-34 (main target of the
work) and six more hydrophobic 23 28 (as synthesis intermediates),
and these intermediaries are also important for comparative studies of
structure and biological activity (SAR). Starting from glycerol (1), we
synthesize the 2,2-dimethyl-1,3-dioxolan-4-yl)methyl acrylates (21, 94%)
and from this, two synthetic routes were investigated to produce the 29-
34 adducts. On Route 1, the adducts 29-34 were produced in one-step
(54 - 82%) from the Michael acceptor 2,3-dihydroxypropyl acrylate 22,
which was prepared in 100% yield from 21. In route 2, MBHA
intermediates 23 - 28 were prepared directly from 21 (90 - 100%) and
these adducts were subsequently processed in adducts 29-34 (70 - 90%).
In the synthesis of adduct 32 was observed the formation of the Michael
addition product 47 and Indolizines unprecedented 48 as co-products of
synthesis and characterized only by CGMS during the synthetic route 2. All
syntheses in this work were developed in industry standards convenient.
The activation reaction by microwave irradiation (MW) was widely used in
most steps of this synthetic work, leading to high chemical yields and
reduced reaction times. / Este trabalho foi realizado no intuito de desenvolver a síntese de
novos adutos de Morita-Baylis-Hillman (AMBH) hidrossolúveis (29-34)
com potenciais atividades antiparasitárias, usando o glicerol (1) como
matéria-prima. Duas rotas sintéticas foram desenvolvidas conduzindo a
doze AMBH inéditos (23 - 34), dos quais seis possuem as características
hidrofílicas 29-34 (alvo principal do trabalho) e as outras seis mais
hidrofóbicas 23 - 28 (como intermediários de síntese), sendo que estes
intermediários são também importantes para estudos comparativos entre
estrutura e atividades biológicas (SAR). Partindo do glicerol (1),
sintetizamos o acrilato de 2,2-dimetil-1,3-dioxalila (21, 94%) e a partir
deste, duas rotas sintéticas foram investigadas para os adutos-alvo 29-
34. Na rota 1, os adutos 29-34 foram produzidos em uma única etapa
sintética (54 - 82%) a partir do aceptor de Michael acrilato de 2,3-
dihidroxipropila 22, que foi preparado em 100% de rendimento a partir de
21. Na rota 2, os AMBH intermediários 23 28 foram preparados em 90 -
100% diretamente de 21 e estes adutos foram subseqüentemente
transformados nos adutos 29-34 (70 - 90%). Na síntese do aduto 32 foi
observado a formação do produto de adição de Michael 47 e da indolizina
inédita 48 como co-produtos de síntese e caracterizados apenas por
CGMS, durante a rota sintética 2. Todas as sínteses neste trabalho foram
desenvolvidas em padrões convenientes a indústria. A ativação reacional
por irradiação de microondas (MO) foi amplamente utilizada na maioria
das etapas sintéticas deste trabalho, conduzindo aos altos rendimentos
químicos e aos tempos reacionais reduzidos.
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Caracteriza??o de res?duo s?lido formado em biodiesel de sebo bovinoPivesso, Paulo Roberto 28 June 2011 (has links)
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Previous issue date: 2011-06-28 / Biodiesel production has increased over the last decade because of the benefits
associated with this fuel, including renewability, domestic feedstock, lower toxicity,
and biodegradability. From 2008, the use of beef tallow as a feedstock for biodiesel
production in Brazil has increased in significance, representing the second largest
source of biodiesel, after soybeans. However, the performance of biodiesel in cold
weather conditions is worse than diesel because of deposition of insoluble at low
temperatures, accelerating the plugging of fuel filters and injectors of the vehicle
engine. Studies have been conducted on beef tallow biodiesel, mostly related to the
properties of thermal and oxidative stability. However, few studies have described the
nature of the precipitate formed and its influence on product quality. Research
suggests that the cause of deposition is related to the nature of saturated esters and
monoacylglycerols as inducing agents. This study monitored the levels of mono-, diand
triacylglycerols, the oxidation stability and the cold filter plugging point (CFPP) in
beef tallow biodiesel samples from two commercial producers in Brazil for a period of
twelve months. Filtered precipitates were analyzed by comparative techniques of GCFID,
HPLC-UV/VIS, HPLC-MS-IT-TOF and TG to verify the nature, using
monopalmitin and monostearin as reference standards. The formation of precipitate
reduced the levels of monoacylglycerols in the beef tallow biodiesel. GC-FID and LCMS-
IT-TOF results confirmed the nature of the deposit as saturated
monoacylglycerols, predominantly monostearin and monopalmitin as the second
major component. Moreover the TG analysis of the residue indicated similar thermal
decomposition of the reference standards. The precipitate did not affect the oxidation
stability of beef tallow biodiesel and the CFPP characteristic of blends up B60.
However, the presence of iron reduced significantly the oxidation stability of
biodiesel / A produ??o de biodiesel aumentou na ?ltima d?cada em fun??o dos benef?cios
associados a este combust?vel, incluindo renovabilidade, mat?rias-primas nacionais,
menor toxicidade e biodegradabilidade. Desde 2008, o uso do sebo bovino como
mat?ria-prima na produ??o de biodiesel no Brasil tem aumentado em import?ncia,
representando a segunda fonte de produ??o, depois da soja No entanto, o
desempenho do biodiesel em condi??es de clima frio ? pior que do ?leo diesel
devido ? ocorr?ncia de materiais insol?veis a baixas temperaturas, acelerando o
entupimento de filtros e injetores de motores de ve?culos. Estudos t?m sido
realizados acerca do biodiesel de sebo bovino, em sua maioria relacionados ?s
propriedades de estabilidade t?rmica e oxidativa; no entanto, poucos abordam a
natureza do precipitado formado e sua influ?ncia na qualidade do biodiesel.
Pesquisas sugerem que a causa da deposi??o esteja relacionada ? natureza de
?steres saturados, sendo os monoacilglicer?is prov?veis agentes indutores. Este
trabalho apresenta os n?veis de mono-, di- e triacilglicer?is, a estabilidade ? oxida??o
e o ponto de entupimento de filtro a frio (PEFF) de amostras de biodiesel de sebo
bovino de dois produtores comerciais, avaliados por um per?odo de 12 meses.
Amostras de precipitados filtrados foram analisadas pelas t?cnicas comparativas de
CG-DIC, CLAE-UV/VIS, CLAE-MS-IT-TOF e TG para verificar a composi??o,
utilizando monopalmitina e monoestearina como padr?es de refer?ncia. Verificou-se
que a forma??o de precipitado reduziu os n?veis de monoacilglicer?is no biodiesel de
sebo bovino. Os resultados cromatogr?ficos confirmaram a natureza do precipitado
como monoacilglicer?is saturados, com predomin?ncia de monoestearina e
monopalmitina como segundo componente majorit?rio. Al?m disso, a an?lise de TG
do precipitado resultou perfil de decomposi??o t?rmica semelhante ao dos padr?es
de refer?ncia. O dep?sito formado n?o afetou a estabilidade ? oxida??o do biodiesel
de sebo bovino e a caracter?stica de PEFF em misturas at? B60. No entanto, a
presen?a de ferro reduziu significativamente a estabilidade ? oxida??o do biodiesel
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Caracteriza??o de res?duo s?lido formado em biodiesel de sebo bovinoPivesso, Paulo Roberto 28 June 2011 (has links)
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Previous issue date: 2011-06-28 / Biodiesel production has increased over the last decade because of the benefits
associated with this fuel, including renewability, domestic feedstock, lower toxicity,
and biodegradability. From 2008, the use of beef tallow as a feedstock for biodiesel
production in Brazil has increased in significance, representing the second largest
source of biodiesel, after soybeans. However, the performance of biodiesel in cold
weather conditions is worse than diesel because of deposition of insoluble at low
temperatures, accelerating the plugging of fuel filters and injectors of the vehicle
engine. Studies have been conducted on beef tallow biodiesel, mostly related to the
properties of thermal and oxidative stability. However, few studies have described the
nature of the precipitate formed and its influence on product quality. Research
suggests that the cause of deposition is related to the nature of saturated esters and
monoacylglycerols as inducing agents. This study monitored the levels of mono-, diand
triacylglycerols, the oxidation stability and the cold filter plugging point (CFPP) in
beef tallow biodiesel samples from two commercial producers in Brazil for a period of
twelve months. Filtered precipitates were analyzed by comparative techniques of GCFID,
HPLC-UV/VIS, HPLC-MS-IT-TOF and TG to verify the nature, using
monopalmitin and monostearin as reference standards. The formation of precipitate
reduced the levels of monoacylglycerols in the beef tallow biodiesel. GC-FID and LCMS-
IT-TOF results confirmed the nature of the deposit as saturated
monoacylglycerols, predominantly monostearin and monopalmitin as the second
major component. Moreover the TG analysis of the residue indicated similar thermal
decomposition of the reference standards. The precipitate did not affect the oxidation
stability of beef tallow biodiesel and the CFPP characteristic of blends up B60.
However, the presence of iron reduced significantly the oxidation stability of
biodiesel / A produ??o de biodiesel aumentou na ?ltima d?cada em fun??o dos benef?cios
associados a este combust?vel, incluindo renovabilidade, mat?rias-primas nacionais,
menor toxicidade e biodegradabilidade. Desde 2008, o uso do sebo bovino como
mat?ria-prima na produ??o de biodiesel no Brasil tem aumentado em import?ncia,
representando a segunda fonte de produ??o, depois da soja No entanto, o
desempenho do biodiesel em condi??es de clima frio ? pior que do ?leo diesel
devido ? ocorr?ncia de materiais insol?veis a baixas temperaturas, acelerando o
entupimento de filtros e injetores de motores de ve?culos. Estudos t?m sido
realizados acerca do biodiesel de sebo bovino, em sua maioria relacionados ?s
propriedades de estabilidade t?rmica e oxidativa; no entanto, poucos abordam a
natureza do precipitado formado e sua influ?ncia na qualidade do biodiesel.
Pesquisas sugerem que a causa da deposi??o esteja relacionada ? natureza de
?steres saturados, sendo os monoacilglicer?is prov?veis agentes indutores. Este
trabalho apresenta os n?veis de mono-, di- e triacilglicer?is, a estabilidade ? oxida??o
e o ponto de entupimento de filtro a frio (PEFF) de amostras de biodiesel de sebo
bovino de dois produtores comerciais, avaliados por um per?odo de 12 meses.
Amostras de precipitados filtrados foram analisadas pelas t?cnicas comparativas de
CG-DIC, CLAE-UV/VIS, CLAE-MS-IT-TOF e TG para verificar a composi??o,
utilizando monopalmitina e monoestearina como padr?es de refer?ncia. Verificou-se
que a forma??o de precipitado reduziu os n?veis de monoacilglicer?is no biodiesel de
sebo bovino. Os resultados cromatogr?ficos confirmaram a natureza do precipitado
como monoacilglicer?is saturados, com predomin?ncia de monoestearina e
monopalmitina como segundo componente majorit?rio. Al?m disso, a an?lise de TG
do precipitado resultou perfil de decomposi??o t?rmica semelhante ao dos padr?es
de refer?ncia. O dep?sito formado n?o afetou a estabilidade ? oxida??o do biodiesel
de sebo bovino e a caracter?stica de PEFF em misturas at? B60. No entanto, a
presen?a de ferro reduziu significativamente a estabilidade ? oxida??o do biodiesel
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