Made available in DSpace on 2014-10-09T12:36:44Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:05Z (GMT). No. of bitstreams: 1 04245.pdf: 2667747 bytes, checksum: 0d0a973c2b8011a3f767e65572ac2262 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:45:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:31Z (GMT). No. of bitstreams: 1 07017.pdf: 4719502 bytes, checksum: 28a724854a3b5a54707b7678f9280cb2 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:47:12Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:28Z (GMT). No. of bitstreams: 1 07968.pdf: 6619312 bytes, checksum: eb2580302affd3cba9bfe5fd6bcf62ef (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:00/03079-7

O yacon (Smallanthus sonchifolius) é uma raiz de origem andina, considerada como um alimento funcional por apresentar em sua composição frutoligossacarídeos (FOS) e compostos fenólicos. Os FOS são polímeros de frutose com grau de polimerização de 3-10 e têm sido designados como prebióticos e fibras alimentares por sua não digestibilidade pelas enzimas do trato digestivo humano e por estimulando seletivamente o crescimento e a atividade de bactérias intestinais promotoras de saúde. Além da ação prebiótica, as raízes de yacon são ricas em compostos fenólicos com propriedades antioxidantes, que protegem o corpo humano dos processos oxidativos. Entretanto, a presença desses compostos torna as raízes suscetíveis à reação de escurecimento enzimático causado pela peroxidase e polifenoloxidase. Diante disso, inicialmente, foi estudada a cinética da inativação térmica e parâmetros termodinâmicos durante o branqueamento dessas enzimas e da enzima inulinase no suco de yacon. O suco de yacon, previamente acidificado com 1% de ácido cítrico foi branqueado com diferentes combinações de tempo-temperatura na faixa de 0-10minutos e 80-100 ºC. O comportamento cinético das três enzimas indicou a presença de duas isoenzimas com diferentes estabilidades térmicas, seguindo o modelo bifásico. A análise cinética demonstrou ainda, a alta resistência térmica das enzimas avaliadas, sendo que a inulinase foi a mais resistente ao calor. A análise termodinâmica indicou que a adição do ácido cítrico ao suco de yacon, provavelmente, causou a desnaturação da maior parte das enzimas que posteriormente foram agregadas durante o branqueamento. Posteriormente, o suco de yacon foi microencapsulado por atomização a fim de avaliar o uso da polidextrose como material de parede através da comparação com a goma arábica que é um dos encapsulantes mais utilizados em alimentos. Os efeitos da concentração dos agentes encapsulantes e da temperatura de secagem no teor de compostos fenólicos totais, atividade antioxidante, frutoligossacarídeos, umidade, atividade de água, solubilidade, higroscopicidade, cor e morfologia foram investigados. Os resultados indicaram que a polidextrose apresentou bom desempenho no microencapsulamento de componentes bioativos do suco de yacon, apresentando alta retenção dos compostos fenólicos e da atividade antioxidante. Em todos os tratamentos avaliados teve comportamento muito similar à goma arábica apresentando boas características, tais como baixa umidade, atividade de água e higroscopicidade e elevada solubilidade. Posteriormente, a cinética e termodinâmica de degradação dos compostos fenólicos e a cinética da degradação da diferença total de cor dessas microcápsulas foram avaliadas sob condições de cinética acelerada de armazenamento, com umidade relativa de 75 e 90% e temperaturas de 35 e 45 ºC. As microcápsulas foram atomizadas na temperatura de 140 ºC com goma arábica e polidextrose na proporção de 10% e armazenadas nessas condições por 35 dias. A degradação dos compostos fenólicos e da diferença total de cor das microcápsulas exibiram cinética de primeira ordem. Em relação à degradação dos compostos fenólicos, para todas as condições de umidade e temperatura, as microcápsulas com goma arábica foram mais estáveis do que as encapsuladas com polidextrose, apresentando maiores tempos de meia vida. Entretanto, os valores dos parâmetros termodinâmicos tiveram valores similares, indicando que a degradação dos fenóis ocorreu de forma similar nas microcápsulas independente do material de parede utilizado. As constantes de velocidades da degradação da diferença total de cor das microcápsulas não apresentaram diferença significativa com o aumento da temperatura e/ou da umidade relativa. Paralelamente, foi avaliada a estabilidade do bagaço de yacon desidratado através das isotermas de sorção e análise termodinâmica. O bagaço é o subproduto do processo de extração do suco, tem baixa atividade de água e potencial para uso em formulações alimentícias devido ao teor de FOS que permanece mesmo após a secagem. Os dados de umidade de equilíbrio de bagaço de yacon desidratado em pó foram determinados nas temperaturas de 20, 30, 40 e 50 ºC e o modelo de Halsey ajustou adequadamente os dados de sorção. As isotermas obtidas foram do tipo III, características de produtos contendo açúcares. / Yacon (Smallanthus sonchifolius) is a root of Andean origin, considered to be a functional food as it presents fructooligosaccharides (FOS) and phenolic compounds in its composition. FOS are fructose polymers with a polymerization degree of 3–10 units and have been referred to as prebiotics and dietary fibers because they are not digestible by the enzymes of the human digestive tract and they selectively stimulate the growth and activity of of health promoting bacteria. Other than their prebiotic action, yacon roots are rich on phenolic compounds with antioxidant properties, which protect the human body from oxidative processes. However, the presence of such compounds makes the roots susceptible to enzymatic browning reaction caused by peroxidase and polyphenoloxidase. Thereby, initially, a study was conducted on the kinetics of thermal inactivation and thermodynamic parameters during blanching of these enzymes as well as inulinase enzyme on yacon juice. The yacon juice, previously acidified with 1% citric acid was blanched with different time-temperature combinations in the ranges of 0-10 minutes and 80-100 °C. The kinetic behavior of the three enzymes indicated the presence of two isoenzymes with different thermal stabilities, following the biphasic model. Furthermore, the kinetic analysis showed high thermal resistance for the evaluated enzymes, where in inulinase was the most heat resistant. Thermodynamic analysis indicated that the adding of citric acid to the yacon juice, probably, caused the denaturation of the most of the enzymes that were subsequently aggregated during blanching. Afterwards, yacon juice was microencapsulated by spray drying with the aim of evaluating the use of polydextrose as wall material through in comparison to gum arabic, which is one of the more often used encapsulants in food. The effects of the concentration of the encapsulating agents and drying temperature in the content of total phenolic compounds, antioxidant activity, fructooligosaccharides, moisture, water activity, solubility, hygroscopicity, color, and morphology were investigated. The results indicated that polydextrose presented a good performance in the encapsulation of yacon juice, presenting high retention of phenolic compounds and antioxidant activity. On all the evaluated treatments, a behavior similar to arabic gum was observed, presenting good characteristics, such as low moisture content, water activity and hygroscopicity and high solubility. Hereafter, the kinetics and thermodynamics of the degradation of phenolic compounds and the kinetics of the degradation of the total color difference of these microcapsules were evaluated under accelerated storage kinetics conditions, with relative humidity of 75 and 90% and temperatures between 35 and 45 °C. The spray drying process was performed under a temperature of 140°C with arabic gum and polydextrose in a 10% concentration and stored under such conditions for 35 days. Degradation of phenolic compounds and total color of microcapsules showed first order kinetics. As of phenolic compound degradation, for all the conditions of relative humidity and temperature the microcapsules with arabic gum were more stable than the ones encapsulated with polydextrose, presenting longer half-lives. Nevertheless, values for the thermodynamic parameters were similar, indicating that the degradation of the phenols occurred in a similar way in the microcapsules, regardless of the wall material used. The kinetic analysis for total color difference of the microcapsules showed that the increase in temperature and/or relative humidity caused no significant difference on the the rate constants. Meantime, the stability of dehydrated yacon bagasse was evaluated by use of sorption isotherms and thermodynamic analysis. The bagasse is a byproduct of the juice extraction process, with low water activity and potential for usage in food formulations due to residual FOS content, even after drying. Equilibrium moisture data for powdered dehydrated yacon bagasse was determined under temperatures of 20, 30, 40, and 50°C and the Halsey model suitably adjusted to the sorption data. The isotherms thus obtained were class III isotherms, typical of sugar rich products.

O yacon (Smallanthus sonchifolius) é uma raiz de origem andina, considerada como um alimento funcional por apresentar em sua composição frutoligossacarídeos (FOS) e compostos fenólicos. Os FOS são polímeros de frutose com grau de polimerização de 3-10 e têm sido designados como prebióticos e fibras alimentares por sua não digestibilidade pelas enzimas do trato digestivo humano e por estimulando seletivamente o crescimento e a atividade de bactérias intestinais promotoras de saúde. Além da ação prebiótica, as raízes de yacon são ricas em compostos fenólicos com propriedades antioxidantes, que protegem o corpo humano dos processos oxidativos. Entretanto, a presença desses compostos torna as raízes suscetíveis à reação de escurecimento enzimático causado pela peroxidase e polifenoloxidase. Diante disso, inicialmente, foi estudada a cinética da inativação térmica e parâmetros termodinâmicos durante o branqueamento dessas enzimas e da enzima inulinase no suco de yacon. O suco de yacon, previamente acidificado com 1% de ácido cítrico foi branqueado com diferentes combinações de tempo-temperatura na faixa de 0-10minutos e 80-100 ºC. O comportamento cinético das três enzimas indicou a presença de duas isoenzimas com diferentes estabilidades térmicas, seguindo o modelo bifásico. A análise cinética demonstrou ainda, a alta resistência térmica das enzimas avaliadas, sendo que a inulinase foi a mais resistente ao calor. A análise termodinâmica indicou que a adição do ácido cítrico ao suco de yacon, provavelmente, causou a desnaturação da maior parte das enzimas que posteriormente foram agregadas durante o branqueamento. Posteriormente, o suco de yacon foi microencapsulado por atomização a fim de avaliar o uso da polidextrose como material de parede através da comparação com a goma arábica que é um dos encapsulantes mais utilizados em alimentos. Os efeitos da concentração dos agentes encapsulantes e da temperatura de secagem no teor de compostos fenólicos totais, atividade antioxidante, frutoligossacarídeos, umidade, atividade de água, solubilidade, higroscopicidade, cor e morfologia foram investigados. Os resultados indicaram que a polidextrose apresentou bom desempenho no microencapsulamento de componentes bioativos do suco de yacon, apresentando alta retenção dos compostos fenólicos e da atividade antioxidante. Em todos os tratamentos avaliados teve comportamento muito similar à goma arábica apresentando boas características, tais como baixa umidade, atividade de água e higroscopicidade e elevada solubilidade. Posteriormente, a cinética e termodinâmica de degradação dos compostos fenólicos e a cinética da degradação da diferença total de cor dessas microcápsulas foram avaliadas sob condições de cinética acelerada de armazenamento, com umidade relativa de 75 e 90% e temperaturas de 35 e 45 ºC. As microcápsulas foram atomizadas na temperatura de 140 ºC com goma arábica e polidextrose na proporção de 10% e armazenadas nessas condições por 35 dias. A degradação dos compostos fenólicos e da diferença total de cor das microcápsulas exibiram cinética de primeira ordem. Em relação à degradação dos compostos fenólicos, para todas as condições de umidade e temperatura, as microcápsulas com goma arábica foram mais estáveis do que as encapsuladas com polidextrose, apresentando maiores tempos de meia vida. Entretanto, os valores dos parâmetros termodinâmicos tiveram valores similares, indicando que a degradação dos fenóis ocorreu de forma similar nas microcápsulas independente do material de parede utilizado. As constantes de velocidades da degradação da diferença total de cor das microcápsulas não apresentaram diferença significativa com o aumento da temperatura e/ou da umidade relativa. Paralelamente, foi avaliada a estabilidade do bagaço de yacon desidratado através das isotermas de sorção e análise termodinâmica. O bagaço é o subproduto do processo de extração do suco, tem baixa atividade de água e potencial para uso em formulações alimentícias devido ao teor de FOS que permanece mesmo após a secagem. Os dados de umidade de equilíbrio de bagaço de yacon desidratado em pó foram determinados nas temperaturas de 20, 30, 40 e 50 ºC e o modelo de Halsey ajustou adequadamente os dados de sorção. As isotermas obtidas foram do tipo III, características de produtos contendo açúcares. / Yacon (Smallanthus sonchifolius) is a root of Andean origin, considered to be a functional food as it presents fructooligosaccharides (FOS) and phenolic compounds in its composition. FOS are fructose polymers with a polymerization degree of 3–10 units and have been referred to as prebiotics and dietary fibers because they are not digestible by the enzymes of the human digestive tract and they selectively stimulate the growth and activity of of health promoting bacteria. Other than their prebiotic action, yacon roots are rich on phenolic compounds with antioxidant properties, which protect the human body from oxidative processes. However, the presence of such compounds makes the roots susceptible to enzymatic browning reaction caused by peroxidase and polyphenoloxidase. Thereby, initially, a study was conducted on the kinetics of thermal inactivation and thermodynamic parameters during blanching of these enzymes as well as inulinase enzyme on yacon juice. The yacon juice, previously acidified with 1% citric acid was blanched with different time-temperature combinations in the ranges of 0-10 minutes and 80-100 °C. The kinetic behavior of the three enzymes indicated the presence of two isoenzymes with different thermal stabilities, following the biphasic model. Furthermore, the kinetic analysis showed high thermal resistance for the evaluated enzymes, where in inulinase was the most heat resistant. Thermodynamic analysis indicated that the adding of citric acid to the yacon juice, probably, caused the denaturation of the most of the enzymes that were subsequently aggregated during blanching. Afterwards, yacon juice was microencapsulated by spray drying with the aim of evaluating the use of polydextrose as wall material through in comparison to gum arabic, which is one of the more often used encapsulants in food. The effects of the concentration of the encapsulating agents and drying temperature in the content of total phenolic compounds, antioxidant activity, fructooligosaccharides, moisture, water activity, solubility, hygroscopicity, color, and morphology were investigated. The results indicated that polydextrose presented a good performance in the encapsulation of yacon juice, presenting high retention of phenolic compounds and antioxidant activity. On all the evaluated treatments, a behavior similar to arabic gum was observed, presenting good characteristics, such as low moisture content, water activity and hygroscopicity and high solubility. Hereafter, the kinetics and thermodynamics of the degradation of phenolic compounds and the kinetics of the degradation of the total color difference of these microcapsules were evaluated under accelerated storage kinetics conditions, with relative humidity of 75 and 90% and temperatures between 35 and 45 °C. The spray drying process was performed under a temperature of 140°C with arabic gum and polydextrose in a 10% concentration and stored under such conditions for 35 days. Degradation of phenolic compounds and total color of microcapsules showed first order kinetics. As of phenolic compound degradation, for all the conditions of relative humidity and temperature the microcapsules with arabic gum were more stable than the ones encapsulated with polydextrose, presenting longer half-lives. Nevertheless, values for the thermodynamic parameters were similar, indicating that the degradation of the phenols occurred in a similar way in the microcapsules, regardless of the wall material used. The kinetic analysis for total color difference of the microcapsules showed that the increase in temperature and/or relative humidity caused no significant difference on the the rate constants. Meantime, the stability of dehydrated yacon bagasse was evaluated by use of sorption isotherms and thermodynamic analysis. The bagasse is a byproduct of the juice extraction process, with low water activity and potential for usage in food formulations due to residual FOS content, even after drying. Equilibrium moisture data for powdered dehydrated yacon bagasse was determined under temperatures of 20, 30, 40, and 50°C and the Halsey model suitably adjusted to the sorption data. The isotherms thus obtained were class III isotherms, typical of sugar rich products.

Made available in DSpace on 2014-10-09T12:36:44Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:05Z (GMT). No. of bitstreams: 1 04245.pdf: 2667747 bytes, checksum: 0d0a973c2b8011a3f767e65572ac2262 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:45:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:31Z (GMT). No. of bitstreams: 1 07017.pdf: 4719502 bytes, checksum: 28a724854a3b5a54707b7678f9280cb2 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:47:12Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:28Z (GMT). No. of bitstreams: 1 07968.pdf: 6619312 bytes, checksum: eb2580302affd3cba9bfe5fd6bcf62ef (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:00/03079-7

To shift from a petroleum-based to a biomass-based economy will require the development not only of biofuels, but also of biorenewable replacements for petroleum-derived chemicals. In this regard, environmentally friendly biomass-derived esters may serve as alternatives to fossil-derived chemicals such as toxic halogenated solvents and glycol ethers. Therefore, esterification of various carboxylic acids that find significant applications in the chemical, pharmaceutical, petrochemical, food, and cosmetic industries has been initiated by the chemical industry. At atmospheric condition, esterification is a reversible reaction limited by the low equilibrium conversion and slow reaction rate, and has recently been performed with excess alcohol to shift the equilibrium conversion. Heterogeneous or homogeneous acid catalysts are used to achieve acceptable reaction rates. The conventional acid-catalyzed process has been extensively developed; but it suffers from problems associated with the generation of side reactions, corrosion of equipment, expensive purification procedures, long reaction times and discharge of acidic wastes. Various attempts on esterification of carboxylic acids with ethanol have previously addressed important issues concerning product distribution, catalyst activity, and kinetics of acid-catalyzed esterification at lower reaction temperatures, but kinetics of uncatalyzed esterification at elevated reaction temperatures are still very limited. It is thus of great interest from a practical viewpoint that more information such as kinetic and thermodynamic parameters are required to develop a possible esterification process without using any catalyst. In this work, therefore, a fundamental study on the uncatalyzed esterification of different aliphatic carboxylic acids with stoichiometric amounts of ethanol was undertaken to examine the possibility of converting the biomass-derived carboxylic acids to ethyl esters and to determine the kinetic and thermodynamic parameters for the uncatalyzed esterification. Experiments were conducted with isothermal batch reactors at temperatures ranging from 298 K to 623 K. A 2nd-order reversible kinetics rate expression was used to fit the experimental data. The thermodynamic and kinetic values estimated were found to vary for different esterification systems studied. The dependence of Keq on temperature for esterification of short-chain and long-chain carboxylic acids varied. Despite the nonlinearity of the Van't Hoff plot for esterification of linoleic acid, the Arrhenius and Eyring plots were linear. Two thermodynamic paths were developed for estimating the equilibrium conversions, and the theoretical values compared well with the experimental results reported in this study. Additional experiments performed to assess the corrosive and catalytic influences of metallic materials on esterification reaction indicated Inconel 625 alloy, nickel wire and stainless steel materials have potential corrosion problems on the uncatalyzed esterification reaction at elevated reaction. However, tantalum and grade 5 titanium materials showed acceptable level of compatibility for similar reaction conditions, and this can encourage the design of a flow reactor system.

This master thesis is dealing with application of an artificial neural network for calculating specific volume of steam. There is described type and construction of the needed neural network. The main outcome of this work is an executable programme, which calculates specific volume of steam for given pressure and temperature, using neural nets.