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A macadâmia (Macadamia integrifolia) é considerada comercialmente uma das nozes mais importantes do mundo por seus atributos sensoriais e nutricionais. Dentre as etapas do beneficiamento desta noz, destacam-se a secagem e a torra como processos térmicos diretamente ligados a sua qualidade. Contudo, eles têm sido relacionados à diminuição da estabilidade oxidativa e da capacidade antioxidante de compostos bioativos, como os ácidos fenólicos. Sendo assim, o objetivo deste trabalho foi caracterizar e comparar a noz macadâmia submetida às etapas de secagem (crua) e de torra, quanto a composição química e sua atividade antioxidante in vitro. Os ensaios realizados para a composição centesimal demonstraram que não houve diferença (p<0,05) entre as amostras crua e torrada, exceto pela umidade e cinzas. Observou-se que macadâmia, cura ou torrada, é uma grande fonte de lipídeos (~77g/100g amostra). Não se verificou diferença no perfil dos ácidos graxos entre as amostras analisadas, prevalecendo monoinsaturados (~58g/100g amostra). Para a avaliação da atividade antioxidante, foram obtidos, das amostras cruas e torradas, os extratos etéreo (EE), alcoólico (EAlc) e aquoso (EAq) e as frações de ácidos fenólicos livre (AFL), esterificados solúveis (AFS) e insolúveis-ligados (AFI). Quanto ao teor de fenólicos totais, através do método com o reagente de Folin-Ciocalteau, o extrato que se destacou foi o EAq, tanto para macadâmia crua quanto para torrada, com os maiores valores em relação aos outros extratos, mas ainda foram menores que as frações. A macadâmia torrada obteve os maiores teores de fenólicos totais com AFL e AFS. A atividade antioxidante foi testada através dos métodos de redução do radical DPPH, de co-oxidação do sistema &#946;-caroteno/ácido linoleico e de oxidação lipídica acelerada em Rancimat. No teste de redução do DPPH, a macadâmia crua foi mais eficiente que a torrada apenas no EE e na AFI. Já para o EAq, o EAlc, a AFL e a AFS, a macadâmia torrada apresentou as melhores porcentagens de redução. No sistema &#946;-caroteno/ácido linoleico, os EAqs tiveram maiores porcentagens de inibição da oxidação que os demais extratos; todas as frações apresentaram porcentagens de inibição muito superiores às dos extratos, mesmo em concentrações menores. Notou-se também que houve queda na capacidade de inibição da oxidação do EE e das três frações (AFL, AFS e AFI), quando se comparam a amostra crua em relação à torrada. No ensaio em Rancimat, o EAlc foi o único, entre extratos e frações de ambas as amostras, a diferir significativamente do controle-negativo em sua ação protetora, entretanto não foi mais eficiente que o TBHQ, utilizado como controle-positivo. Neste estudo, a diferença de atividade entre os métodos ficou clara, contudo também se evidenciou que o tratamento térmico da torra é capaz de alterar a capacidade antioxidante dos compostos fenólicos presentes na macadâmia. / Macadamia (Macadamia integrifolia) is considered one of the most important nuts in the world for their nutritional and sensory attributes. In the macadâmia nut processing, drying and roasting steps stand out because they are thermal processes directly related with its quality. However, they have been associated to the decrease of oxidative stability and antioxidant activity of bioactive compounds such as phenolic acids. Therefore, the aim of this study was to characterize and compare the dried (raw) and roasted macadamia nuts, their chemical composition and in vitro antioxidant activity. The composition assays shown that there was no difference between raw and roasted samples of macadamia (p<0,05), except for moisture and ash. It was also observed that both samples are source of oil (~77g/100g macadamia). There was no difference (p<0,05) in the fatty acids profile of the samples, with the predominance of monounsaturated fatty acids (~58g/100g macadamia). For the evaluation of antioxidant activity, the ether (EE), alcoholic (EAlc) and aqueous (EAq) extracts and the free phenolic acids (AFL), soluble esterified acids (AFS) and insoluble-bound acids (AFI) fractions were obtained from raw and roasted samples. In the total phenolic content, by Folin-Ciocalteau method, the EAq stood out for raw and roasted macadamia nuts with a high content, compared with the other extracts, but it was lower than the acid phenolic fractions. The roasted macadamias showed the highest levels of total phenolics in AFL and AFS. The antioxidant activity was obtained by the methods of DPPH radical reduction, of &#946;-carotene/linoleic acid co-oxidation system and accelerated lipid oxidation in Rancimat. In the DPPH test, raw macadamia reduced more efficiently than roasted only in EE and AFI. For the EAq, EAlc, AFL and AFS, the roasted macadamia nuts showed the best percentages of reduction. In &#946;-carotene/linoleic acid system, EAqs of both samples showed similar results and had the highest percentage of oxidation inhibition than the other extracts. All of fractions showed much higher percentages of inhibition than extracts, even at lower concentrations. A decrease in the ability to inhibit oxidation of EE and the three fractions (AFL, AFS and AFI) was also noticed, when comparing the raw samples with the roasted. In Rancimat test, the EAlc was the only, of the extracts and fractions of both samples, witch differed significantly from negative control in its protective activity; however it was not more effective than TBHQ, used as positive control. In this study, the differences between the methods were noticeable, but it was also showed that the thermal treatment of the roasting was able to modify the antioxidant capacity of phenolic compounds in macadamia nuts.

Neste trabalho, o forno de microondas focalizadas (CEM, Star System 2) e o forno de microondas doméstico adaptado (CCE, MW - 850) foram utilizados para o processo térmico descontínuo e contínuo, respectivamente para reduzir a atividade da POD e PFO presentes na água de coco. No processo descontínuo um sensor de fibra óptica permaneceu em contato direto com as amostras, o que permitiu a obtenção de perfis precisos da temperatura em função do tempo e a determinação dos parâmetros cinéticos D e z para as enzimas, no intervalo de temperatura entre 50 e 100 °C. No processo contínuo, a aquisição dos dados de temperatura foi realizada por termopar tipo T localizado na saída da cavidade do forno e alcançou temperatura máxima entre 66 e 91 °C. Para avaliar a influência dos principais constituintes químicos da água de coco na atividade enzimática soluções simuladas (água; água/açúcares; água/sais; água/sais/açúcares) e água de coco estéril com adição de POD e PFO comerciais foram submetidas ao processo descontínuo por microondas. Os parâmetros cinéticos determinados para as enzimas come rciais nas soluções simuladas obedeceram à cinética de 1ª ordem e os valores D e z foram respectivamente: PFO/água (D93°C = 16 s, z = 35,5 °C), PFO/açúcares (D91°C = 18 s, z = 33,0 °C), POD/água (D92°C = 44 s, z = 24,0 °C), POD/açúcares (D92°C = 21 s, z = 19,5 °C), PFO/água de coco estéril (D84,45ºC = 43 s, z = 39,5 °C) e POD/água de coco estéril (D86,54ºC = 20 s, z = 19,3ºC). Nas soluções simuladas com sais, as atividades iniciais das enzimas foram significativamente menores. Na água de coco as enzimas apresentaram resistência térmica maior quando comparadas aos resultados das soluções simuladas apresentando D92,20°C = 52 s e z = 17,6 °C para a PFO e D92,92°C = 16 s e z = 11,5 °C para a POD. Nos ensaios em processo contínuo a redução da atividade da PFO obedeceu à cinética de 1a ordem e os resultados corroboraram àqueles determinados para o sistema descontínuo. A POD não apresentou atividade residual detectável para temperaturas de saída acima de 88 °C, mas abaixo de 77 ºC a atividade residual foi próxima dos resultados para a POD na água de coco obtidos pelo processo descontínuo. É importante mencionar que para todos os ensaios com água de coco processada, seja no sistema descontínuo ou contínuo, não foi observada a coloração rósea, normalmente atribuída à ação enzimática. Somado a isso, o estudo mostrou que o tratamento térmico por microondas foi mais efetivo na redução da atividade da POD e PFO presentes em água de coco quando comparado com a pasteurização convencional o que torna o uso das microondas uma boa alternativa de processamento para a conservação desse alimento. / In this work a focused microwave oven (CEM, Star System 2) and an adapted domestic microwave oven (CCE, MW - 850) were employed to reduce POD and PPO activity using batch and continuous processing. In a batch processing an optic fiber sensor was kept in direct contact with the samples, thus precise temperature as a function of time profiles were obtained as well as the kinetic parameters (D and z) in the range between 50 and 100°C. In the continuous processing temperature data were obtained by type T thermocouples in the entrance and exit of the microwave oven cavity in the range between 66 and 90°C. Simulated solutions (water; water/sugars; water/salts; water/sugars/salts) and sterile coconut water were formulated with addition of commercial POD and PPO and were exposed to batch processing by microwaves to evaluate the influence of the main chemical substances present in coconut water on the enzymatic activity. Commercial enzymes in the simulated solutions followed a first order order kinetic model. D and z values were: PPO/water (D93°C = 16 s, z = 35.5 °C), PPO/sugars (D91°C = 18 s, z = 33.0 °C), POD/water (D91,5°C = 44 s, z = 24.0 °C), POD/sugars (D92°C = 21 s, z = 19.5 °C), PPO/sterile coconut water (D84,45ºC = 43 s, z = 39.5 °C) and POD/ sterile coconut water (D86,54ºC = 20 s, z = 19.3 ºC). Added salts influenced commercial PPO and POD stability and significantly reduced their activity. In coconut water the enzymes were more thermally resistant when compared to the simulated solution presenting D92,9°C = 52 s and z = 17.6 °C for PPO and D92,9°C = 16 s and z = 11.5 °C for POD. In continuous processing PPO inactivation followed a first order kinetic model and the results were similar to those obtained in the batch processing. POD didn´t present residual activity at exit temperatures above 88 ºC. Below 77 ºC residual activity was close to that of the POD/coconut water treated by batch processing. An important fact is that for all assays with coconut water, wether batch or continuous process was employed, no pink color (that is attributed to enzyme activity) was observed. Besides this study has shown that thermal treatment by microwaves was more efficient than conventional thermal treatment in reducing PPO and POD activity in coconut water, therefore microwaves are an interesting alternative for conservation of this food.

De nos jours la protection de l’environnement et des personnes nécessite le recours à des capteurs permettant de suivre le déplacement de phénomènes mobiles pour prédire et agir sur leur évolution (ex : nuages polluants, incendies,nappe d’hydrocarbures). Ces phénomènes physiques sont souvent modélisables par des équations aux dérivées partielles (EDP) éventuellement non linéaires. La mise au point d'un outil prédictif pour l'aide à la décision nécessite l'évaluation de certains paramètres d'entrée. Dans ces domaines, les capteurs sont en général coûteux et en nombre limité. Toutefois, avec les récentes avancées technologiques il devient envisageable de concevoir des systèmes mobiles peu coûteux et de déployer un groupe de véhicules en réseau dans un certain nombre d'environnements à risque.Le sujet de recherche étudié et présenté dans ce rapport concerne le développement et la validation de stratégies optimales de déplacement d'un ensemble de capteurs pour l'identification paramétrique en ligne des systèmes d' EDP caractérisés par une ou plusieurs sources mobiles. Le travail présenté est destiné à développer une méthodologie complète(théorie, méthodes numériques, plate-forme expérimentale)en vue de réaliser une conception optimale d'expériences dans le cadre de problèmes mal posés non-linéaires associés à l'évaluation de paramètres dans des systèmes décrits par des EDP en génie thermique. / Nowadays the environment and people protection requires the use of sensors in order to monitor the movement of mobile phenomena and to predict and act on their evolution (ex: polluting cloud, fires, oil spill). These physical phenomena are often modelled by nonlinear partial differential equations (PDE). Development of a predictive tool for the decision support requires the assessment of some input parameters. In such a context, sensors were generally expensive. However, recent technological advances have reduced manufacturing costs and it becomes possible to develop low-cost mobile systems and to deploy a group of networked vehicles in potentially risky environments.Research topic studied and presented in this thesis concerns the development and validation of optimal strategies for moving a set of sensors for the parametric identification of PDE systems characterized by one or more mobile heating sources. This work is intended to develop a comprehensive methodology (theory, numerical methods, and experimentation) in order to achieve an optimal design of experiments in the context of nonlinear ill-posed problems related to the evaluation of parameters in systems described by PDE in thermal engineering.

The development and advancement of microelectronics technology have been dramatically. The time and cost, for research and optimization of process and equipment, can be saved by using flow simulation. The governing equations of flow field, inside chemical vapor deposition (CVD) reactor, are constructed, dispersed, and solved by grid mesh and numerical method. At present, rapid thermal process (RTP) is becoming more important and popular for thin-film depositing technology. In this thesis, vertical type single wafer RTCVD reactor in poly-silicon thin-film depositing process is analyzed by numerical method. Several operating process parameters, such as: (a) the gap between shower head and wafer surface, (b) gas inlet velocity in shower head, and (c) operating pressure inside chamber of reactor, are considered for discussion and analysis of steady or unsteady phenomenon in three steps of thin-film depositing process, including (¢¹) heating for wafer, (¢º) deposition in steady state, (¢») cooling after deposition etc.. As shown in the results, each operating parameters performs different relations and phenomenon in these steady and unsteady steps: Operating pressure can affect the activity of chemical reaction strongly in unsteady or steady region. Larger gap between wafer and shower head causes less influence by flow effects or buoyancy. And also, radiation heat transfer, which is adopted by RTCVD process, can decrease the influence of some parameters on flow field.

Title from PDF of title page. / Document formatted into pages; contains 73 pages. / Thesis (M.S.E.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The goals of this research project were the design and construction of a carbon nanotube (CNT) reactor based on the plasma enhanced chemical vapor deposition (PECVD) principle and the development of a method for directed assembly of CNTs by catalyst patterning. PECVD was selected as the growth method due to the requirement of a catalyst for the growth process, thereby facilitating directed assembly and controlled diameter CNT growth at well-defined locations. The reactor was built in accord with horizontal flow design using standard ultra high vacuum components. The controllable parameters of the reactor include sample temperature, DC plasma intensity, chamber pressure, gas flow ratios, and total gas flow. The most favorable parameters for growing CNTs of well defined length, diameter, and separation were obtained by initially using parameter values obtained from literature, then optimized by changing a parameter and noting the effect on CNT growth. / ABSTRACT: Catalyst patterns for the directed assembly of CNTs were prepared by electron-beam lithography (EBL). Experiments were performed that demonstrated the feasibility of using lithographic methods to achieve directed assembly of carbon nanotubes for the manufacture of CNT devices. Experiments focusing on growth interruption and regrowth of CNTs were conducted to investigate methods of introducing tailored branching points into carbon nanotubes during the growth process. These experiments clearly demonstrate that growth interruption increases the occurrence of CNT branching. An analysis of the relationships between CNT diameter, branching points, and the number of growth steps was conducted. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

La biomasse lignocellulosique est considérée comme une ressource de carbone renouvelable possédant un grand potentiel pour la une valorisation énergétique et chimique. La torréfaction de la biomasse sèche (de type bois) est un procédé de transformation thermique s’effectuant à des températures comprises entre 200°C et 300°C, et un temps de séjour compris entre quelques minutes et plusieurs heures, opérant sous pression atmosphérique et en défaut d’air. Le produit principal de la torréfaction est un combustible solide hydrophobe et stable. Cette opération génère des coproduits gazeux à haute température qui sont habituellement considérés comme des effluents pénalisants, apportant au mieux un appoint d’énergie pour le procédé. Pourtant, de nombreux constituants présents dans les condensats – récupérés par condensation des coproduits de torréfaction – pourraient être valorisés comme produits chimiques bio-sourcés. L'objectif de la thèse est de proposer un procédé de séparation-purification pour les composés condensables présents dans ces effluents gazeux. Ces condensats constituent une phase majoritairement aqueuse, contenant plus de 150 espèces organiques identifiées. Les espèces minoritaires sont présentes dans des proportions variables suivant le bois torréfié. Enfin il s’agit d’un mélange réactif et thermiquement instable, où différents équilibres chimiques sont présents. Une analyse des caractéristiques physico-chimiques des condensats a permis de proposer un milieu modèle limité à une dizaine de composés. Un modèle représentatif du comportement thermodynamique de ce mélange réactif à large spectre de masse moléculaire a été sélectionné et les paramètres d’interaction binaire identifiés. Des données expérimentales d’équilibres liquide-vapeur ont été acquises pour valider en partie ce modèle. Les composés cibles et les objectifs du procédé de valorisation ont été choisis et plusieurs stratégies de valorisation ont été élaborées et simulées sous Prosim+ sur la base de la modélisation thermodynamique. Cette étude a permis d’évaluer ces différentes stratégies en termes d’efficacité énergétique et de pureté des produits finaux pour une potentielle mise en place à l’échelle industrielle de cette filière. / Lignocellulosic biomass is considered as a renewable carbon resource with great potential for the energy and chemical recovery. Torrefaction is a thermal process carried out at temperatures below 300°C, under inert atmosphere, at atmospheric pressure, and with residence times for the solid biomass ranging from few minutes to several hours. Torrefied wood is a solid product constituted by more than 70% of the initial mass with properties close to those of coal. The 30% remaining part is a gaseous effluent, composed of about one third of non-condensable gases – carbon monoxide and carbon dioxide – and two thirds of condensable species. Currently, torrefied wood is the main product of interest and is usually transformed into energetic gases by the gasification process or directly used as coal for combustion. Conversely, gaseous by-products are considered at present time as a waste and in the best case are burned to provide energy to the process. Yet, the recovery and valorization of the condensable fraction as bio-sourced chemicals is worth considering. The aim of the thesis is to propose a separation-purification process for condensable chemicals of the waste gas. This condensable fraction is a predominantly aqueous phase, containing more than 150 identified organic species. Minority species are present in varying proportions depending on torrefied wood. Finally, it is a reactive and thermally unstable mixture, where different chemical equilibria are present. An analysis of the physicochemical characteristics of the condensable fraction allowed selecting a limited number of compounds to model the mixture. A representative model of the thermodynamic behavior of the reactive mixture has been selected and the binary interaction parameters identified. Experimental vapor-liquid equilibria data were acquired in part to validate this model. The target compounds and objectives of the recovery process were selected and several development strategies were developed and simulated in ProSim+ on the basis of thermodynamic modeling. This study assessed these different strategies in terms of energy efficiency and purity of the products for potential implementation on an industrial scale of this sector.

Neste trabalho, o forno de microondas focalizadas (CEM, Star System 2) e o forno de microondas doméstico adaptado (CCE, MW - 850) foram utilizados para o processo térmico descontínuo e contínuo, respectivamente para reduzir a atividade da POD e PFO presentes na água de coco. No processo descontínuo um sensor de fibra óptica permaneceu em contato direto com as amostras, o que permitiu a obtenção de perfis precisos da temperatura em função do tempo e a determinação dos parâmetros cinéticos D e z para as enzimas, no intervalo de temperatura entre 50 e 100 °C. No processo contínuo, a aquisição dos dados de temperatura foi realizada por termopar tipo T localizado na saída da cavidade do forno e alcançou temperatura máxima entre 66 e 91 °C. Para avaliar a influência dos principais constituintes químicos da água de coco na atividade enzimática soluções simuladas (água; água/açúcares; água/sais; água/sais/açúcares) e água de coco estéril com adição de POD e PFO comerciais foram submetidas ao processo descontínuo por microondas. Os parâmetros cinéticos determinados para as enzimas come rciais nas soluções simuladas obedeceram à cinética de 1ª ordem e os valores D e z foram respectivamente: PFO/água (D93°C = 16 s, z = 35,5 °C), PFO/açúcares (D91°C = 18 s, z = 33,0 °C), POD/água (D92°C = 44 s, z = 24,0 °C), POD/açúcares (D92°C = 21 s, z = 19,5 °C), PFO/água de coco estéril (D84,45ºC = 43 s, z = 39,5 °C) e POD/água de coco estéril (D86,54ºC = 20 s, z = 19,3ºC). Nas soluções simuladas com sais, as atividades iniciais das enzimas foram significativamente menores. Na água de coco as enzimas apresentaram resistência térmica maior quando comparadas aos resultados das soluções simuladas apresentando D92,20°C = 52 s e z = 17,6 °C para a PFO e D92,92°C = 16 s e z = 11,5 °C para a POD. Nos ensaios em processo contínuo a redução da atividade da PFO obedeceu à cinética de 1a ordem e os resultados corroboraram àqueles determinados para o sistema descontínuo. A POD não apresentou atividade residual detectável para temperaturas de saída acima de 88 °C, mas abaixo de 77 ºC a atividade residual foi próxima dos resultados para a POD na água de coco obtidos pelo processo descontínuo. É importante mencionar que para todos os ensaios com água de coco processada, seja no sistema descontínuo ou contínuo, não foi observada a coloração rósea, normalmente atribuída à ação enzimática. Somado a isso, o estudo mostrou que o tratamento térmico por microondas foi mais efetivo na redução da atividade da POD e PFO presentes em água de coco quando comparado com a pasteurização convencional o que torna o uso das microondas uma boa alternativa de processamento para a conservação desse alimento. / In this work a focused microwave oven (CEM, Star System 2) and an adapted domestic microwave oven (CCE, MW - 850) were employed to reduce POD and PPO activity using batch and continuous processing. In a batch processing an optic fiber sensor was kept in direct contact with the samples, thus precise temperature as a function of time profiles were obtained as well as the kinetic parameters (D and z) in the range between 50 and 100°C. In the continuous processing temperature data were obtained by type T thermocouples in the entrance and exit of the microwave oven cavity in the range between 66 and 90°C. Simulated solutions (water; water/sugars; water/salts; water/sugars/salts) and sterile coconut water were formulated with addition of commercial POD and PPO and were exposed to batch processing by microwaves to evaluate the influence of the main chemical substances present in coconut water on the enzymatic activity. Commercial enzymes in the simulated solutions followed a first order order kinetic model. D and z values were: PPO/water (D93°C = 16 s, z = 35.5 °C), PPO/sugars (D91°C = 18 s, z = 33.0 °C), POD/water (D91,5°C = 44 s, z = 24.0 °C), POD/sugars (D92°C = 21 s, z = 19.5 °C), PPO/sterile coconut water (D84,45ºC = 43 s, z = 39.5 °C) and POD/ sterile coconut water (D86,54ºC = 20 s, z = 19.3 ºC). Added salts influenced commercial PPO and POD stability and significantly reduced their activity. In coconut water the enzymes were more thermally resistant when compared to the simulated solution presenting D92,9°C = 52 s and z = 17.6 °C for PPO and D92,9°C = 16 s and z = 11.5 °C for POD. In continuous processing PPO inactivation followed a first order kinetic model and the results were similar to those obtained in the batch processing. POD didn´t present residual activity at exit temperatures above 88 ºC. Below 77 ºC residual activity was close to that of the POD/coconut water treated by batch processing. An important fact is that for all assays with coconut water, wether batch or continuous process was employed, no pink color (that is attributed to enzyme activity) was observed. Besides this study has shown that thermal treatment by microwaves was more efficient than conventional thermal treatment in reducing PPO and POD activity in coconut water, therefore microwaves are an interesting alternative for conservation of this food.

Orientador: Pilar Rodriguez de Massaguer / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-16T13:46:22Z (GMT). No. of bitstreams: 1 NolascoJunior_Jonas_D.pdf: 1793020 bytes, checksum: 50a108545c351293fc67eba7a94f669d (MD5) Previous issue date: 2010 / Resumo: Nesta pesquisa foi verificada a eficiência de tratamento térmico UHT para mostos a base de caldo de cana e melaço, otimizado para preservação máxima (> 98,7%) do conteúdo dos açúcares sacarose, glicose e frutose causando 3 reduções logarítmicas no micro-organismo alvo, os esporos de Geobacillus stearothermophilus ATCC 1518. Os mostos tratados termicamente tiveram suas características fermentativas avaliadas utilizando as linhagens industriais de leveduras LNF SA-1 e LNF BG-1, utilizadas na produção de bioetanol. A eficiência dos processos térmicos otimizados foi avaliada em unidade piloto de esterilização contínua Microthermics® com aquecimento indireto utilizando os binômios 125ºC/30s, 130ºC/11s, 130ºC/37s e 135ºC/5s, selecionados a partir de estudos cinéticos de destruição térmica dos esporos de G. stearothermophilus ATCC 1518 nas temperaturas 98º, 110ºC, 120ºC, 122,5ºC e 130ºC e dos açúcares sacarose, glicose, frutose e açúcares redutores totais, ART, nas temperaturas 110ºC, 120ºC, 130ºC e 140ºC, utilizando como meio mosto a 21,5ºBrix e pH 6. Os estudos cinéticos foram realizados em batelada com tubos TDT, 6 mm DI x 8 mm DE x 100 mm de comprimento. O protocolo de processo representado pelo binômio 135ºC/5s foi obtido por extrapolação. O processo térmico contínuo se mostrou mais eficiente que o processo predito através dos ensaios cinéticos em batelada. O número de reduções logarítmicas médio de 2,58 obtido experimentalmente, (nintegral-biológico), em cada um dos protocolos de processo utilizado, foi 7,35% maior que os valores calculados de 2,41, (nintegral-calculado), utilizando os perfis de temperatura obtidos em cada uma das secções da unidade piloto de esterilização, estimados com a velocidade média de escoamento. A preservação da sacarose foi maior que 99,20% enquanto que a preservação dos açúcares redutores totais foi superior a 99,52%. Nos dois processos térmicos com os binômios 130ºC/37s os valores de nintegral-biológico foram maiores que 5,87 e 7,47 e preservação dos açúcares mínima de 99.45%. Teoricamente qualquer dos protocolos de processos térmicos é capaz de causar 108 reduções logarítmicas nos Lactobacillus sp, contaminante comumente encontrados nos mostos durante fermentação. Com relação às características fermentativas dos mostos tratados termicamente, as velocidades específicas máximas de crescimento diminuíram com o aumento da temperatura de tratamento térmico dos mostos de 0,42 h-1 para 0,19 h-1 para LNF SA-1 e de 0,57 h-1 para 0,09 h-1 para LNF BG-1. Os tempos de adaptação obtidos para a linhagem LNF SA-1 variaram de 3,10 h a 4,97 h, mas, em mostos tratados na temperatura mais elevada de 135ºC por 5s, foi de 11,17 h. Para a linhagem LNF BG-1 os tempos de adaptação obtidos variaram de 5,92 h para 6,65 h para os binômios 125ºC/30s, 130ºC/11s e 130ºC/37s, mas no tratamento com o binômio 135ºC/5s foi obtido 10,88 h. A produtividade das leveduras ficou entre 0,24-0,34 g etanol/g de célula/h enquanto que o rendimento em etanol variou de 87,56% a 89,73%, valores dentro dos padrões industriais. Máximo rendimento foi obtido quando foi utilizado mosto tratado a 130ºC/37s em que foi obtido valor de nintegral-biológico maior que 5,87, indicando que os protocolos de tratamento térmicos podem ter exercido diferentes efeitos sobre a disponibilidade de macro e micro nutrientes essenciais para as leveduras / Abstract: In this research is verified the efficiency of a UHT heat treatment process for musts based on sugar cane juice and molasses optimized for maximum preservation of the content in the sugars sucrose, glucose and fructose, using as target the heat resistant spores of Geobacillus stearothermophilus ATCC 1518. Heat treated musts had their fermentative characteristics evaluated using the industrial yeast strains LNF SA-1 and LNF BG-1 for the production of bioethanol in Brazil. The efficiency of the thermal graphically optimized processes was assessed in continuous sterilization Microthermics® pilot plant with indirect heating following the binomials 125ºC/30s, 130ºC/11s, 130ºC/37s and 135ºC/5s, selected from thermal destruction kinetic studies of G. stearothermophilus spores at the temperatures 98ºC, 110ºC, 120ºC, 122.5ºC, 125ºC and 130ºC, and of the sugars sucrose, glucose, fructose and total reducing sugars, TRS, at the temperatures 110ºC, 120ºC, 130ºC and 140ºC, in must media, 21.5ºBrix and pH 6.4. Kinetic studies were carried out in batch, using TDT tubes 6 mm DI x 8 mm DE x 100 mm length. The process condition of the binomial 135ºC/5s was obtained by extrapolation. The continuous heat process was more efficient than the predicted from the batch kinetic tests. The mean number, 2.58, of integral log reduction experimentally obtained for the target microorganism, (nintegral-biological), was 7.35% higher than the mean number, 2.41, of integral calculated values, (nintegral-calculated), using the temperature profile estimated for each of section of the pilot unit with the mean flow velocity. It was found that sugar retention in the musts thermally processed was higher than 99.2% and 99.52% for sucrose and total reducing sugar, respectively. The two thermal processes that followed the binomial 130ºC/37s resulted in nintegral-biological greater than 5.87 and 7.47 with minimal preservation of sugars of 99.45%. Theoretically any of these processes is capable of causing 108 decimal reductions on Lactobacillus sp, typical contaminant found in musts and fermentation. Fermentation characteristics of heat-treated musts were assessed and the kinetic responses of the yeasts in terms of their maximum specific growth rates, in the heat treated musts, decreased with increase in heat treatment temperature of the musts from 0.42 h-1 to 0.19 h-1 for LNF SA-1 and from 0.57 h-1 to 0.09 h-1 for LNF BG-1. The adaptation times obtained for strain LNF SA-1 varied from 3.10 h to 4.97 h, but in musts treated with the highest temperature, 135ºC for 5s, the value was 11.17 h. For the strain LNF BG-1 the adaptation times varied from 5.92 h to 6.65 h, but in musts treated with the highest temperature, 135ºC for 5s, the value was 10.88 h. Cell productivity was in the range of 0.24-0.34 g ethanol/g of cell/h and the yield was in the range 87.56 - 89.73%. Maximum fermentation yield was obtained using musts treated with the binomial 130ºC/37s, for which integral biological n-values found was greater than 5.87, suggesting that the thermal treatment protocols may have exerted different effects on availability of macro and micro essential nutrients for yeasts / Doutorado / Doutor em Ciência de Alimentos

Orientadores: Rubens Maciel Filho, Andre Luiz Jardini Munhoz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-14T19:20:20Z (GMT). No. of bitstreams: 1 Bineli_AulusRobertoRomao_M.pdf: 24103427 bytes, checksum: e0dc4ef614d43eab9b12a55f01124378 (MD5) Previous issue date: 2009 / Resumo: Em tratamentos térmicos de têmpera há uma grande dificuldade em entender os diferentes perfis de resfriamento que ocorrem na superfície e no interior dos materiais, e que definem o controle da estrutura formada e das propriedades finais desejadas. A formação de diferentes tipos de estruturas no mesmo material pode ocorrer devido ao resfriamento não uniforme provocado pelas condições fluidodinâmicas do tanque e do fluido refrigerante, os quais determinam as taxas de resfriamento e o valor do coeficiente de transferência de calor. Além disso, há muito pouco na literatura sobre os critérios para a construção de tanques de têmpera. Portanto este trabalho investiga por meio da Fluidodinâmica Computacional (CFD), utilizando o software ANSYS CFX® 11, duas configurações de um sistema de agitação submerso em tanque de têmpera e o impacto das condições fluidodinâmicas e das propriedades físicas do fluido sobre a uniformidade do resfriamento e no coeficiente de transferência de calor na interface do bloco de aço. Como conseqüência as simulações permitem a verificação de alternativas de como o processo pode ser melhorado a partir deste tipo de análise. O processo físico estudado consiste no resfriamento de um bloco de aço nas dimensões 2,3m x 1,2m x 0,86m imerso em tanque com água de dimensões 8,7m x 2,8m x 4,0 m com um sistema de agitação de jato submerso distribuídos em vários bicos reguladores de saída de água. Foram realizadas duas simulações, a primeira envolvendo o sistema de agitação localizado sob o bloco. Na segunda, entretanto, foi acrescentado um sistema de agitação localizada nas laterais do material na tentativa de homogeneizar o fluxo do fluido entorno do bloco, consequentemente sobre a uniformidade do resfriamento. Os resultados deste trabalho indicam que o sistema foi suscetível a variação das propriedades físicas do fluido e do fluxo sobre o material o que levou a grandes variações na curva de resfriamento para o primeiro caso. Contudo, a implementação do sistema lateral de agitação promoveu uma melhora significativa na uniformidade da têmpera, além disso, o modelo foi capaz de predizer as curvas de resfriamento, os coeficientes de transferência de calor na interface do material, e os fluxos do fluido no tanque. A análise discutida fornece informações de como o software pode melhorar o controle do processo de resfriamento por estudos sobre a uniformidade da têmpera, o que pode auxiliar os engenheiros na concepção e desenvolvimento de novos projetos de tanque levando-se em consideração a forma e o tipo do sistema de agitação, bem como a geometria do tanque e do material, e o fluido utilizado no processo. Esta abordagem pode produzir melhorias significativas na qualidade do material enquanto simultaneamente prevê condições para redução de distorções do material durante o tratamento térmico. / Abstract: In the quenching heat treatment is a great difficulty to understand the different cooling profiles occurring at the surface and subsurface of the material, that define the structure formed and the final properties desired. The formation of different types of structures in the material can occurs due to uneven cooling caused by fluid dynamic conditions of the tank, which determine the cooling rates and the heat transfer coefficient. Moreover, there is very little literature concerning the criteria for the construction of quenching tanks. Therefore in this work was analyzed by means of Computational Fluid Dynamics (CFD), two configurations of submerged agitation system and the impact of fluid dynamic conditions and the physical properties of the fluid on the cooling uniformity and the heat transfer coefficient at the interface of the steel block. The simulations performed allow the verification of alternatives of how the process can be improved from this type of analysis. The physical process studied consist in the cooling of a steel block with dimensions 2.3m x 1.2m x 0.86m immersed in water tank with dimensions 8.7m x 2.8m x 4.0m with submerged agitation system. There were two simulations, the first involving the agitation system located under the block. In the second, however, was added agitation system located next the sides of the material in an attempt to homogenize the fluid flow around the block, consequently on the uniformity of cooling. The results indicate that the system was susceptible to variations in the fluid properties and fluid flow on the material which led to large variations in the cooling curve for the first case. The implementation of the sideway agitation system led to a significant improvement in uniformity of quenching, in addition, the model was able to predict the cooling curves, the heat transfer coefficient at the interface of the material, and fluid flow in the tank. The analysis provides information about how software can improve the control of the cooling process by studies of quench uniformity, which can help engineers in the design and development of new tank taking into account the type of agitation system, tank geometry and material, and the fluid used in the process. This approach can produce significant improvements in the quality of the material while simultaneously provide conditions to reduce distortions in the material during heat treating. / Mestrado / Mestre em Engenharia Química