Orientador: Miriam Dupas Hubinger / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T02:50:30Z (GMT). No. of bitstreams: 1 Ferrari_CristhianeCaroline_M.pdf: 1666755 bytes, checksum: fa3100a4126563ef9d7341d049583dba (MD5) Previous issue date: 2005 / Resumo: O presente trabalho teve como objetivo estudar a cinética de desidratação osmótica de pedaços de melão em soluções de sacarose e maltose, avaliando-se parâmetros de textura e cor ao longo do processo. Cubos de melão da variedade Cucumis melo inodorus, cultivar Gold Mine, de 20 mm foram imersos em soluções hipertônicas de sacarose ou maltose nas concentrações de 40 a 60°Brix e o processo foi conduzido por 8 horas com temperatura controlada (30 ou 40°C) e agitação de 120 rpm. Perda de água e de peso, incorporação de sólidos na fruta, atividade de água, cor e textura foram analisadas ao longo do processo em função da temperatura de tratamento, tipo e concentração da solução. O ponto final de equilíbrio e os coeficientes de difusão para a água e os açúcares foram estimados através de um modelo empírico da literatura, baseado na equação de Fick, comparando-se os efeitos da sacarose e da maltose na transferência de massa durante o processo. Para todos os ensaios, a perda de água e de peso aumentaram significativamente com a elevação da temperatura e da concentração da solução desidratante, entretanto os ensaios com maltose promoveram uma maior taxa de saída de água da fruta e menor ganho de sólidos. As características de cor da fruta fresca permaneceram praticamente inalteradas pela desidratação osmótica, observando-se apenas uma intensificação da cor ocasionada pelo aumento dos valores do parâmetro b* e do croma C*, devido à concentração de pigmentos provocada pela perda de água ao longo do tempo. Em relação à textura, houve um aumento na natureza viscosa e perda de elasticidade durante o processo, por conseqüência da incorporação de sólidos, que causa uma plasticidade na estrutura, porém a maltose se mostrou mais efetiva na manutenção das características de textura da fruta fresca. Foram selecionadas as condições mais favoráveis para cada uma das respostas estudadas, com o intuito de se realizar uma análise sensorial, sendo que, especificamente para estes ensaios, o tempo de tratamento foi de duas horas, determinado a partir das cinéticas de perda de água, ganho de sólidos e textura. Os resultados da avaliação sensorial revelaram que a desidratação osmótica forneceu um produto com boa aceitação pelo consumidor. / Abstract: The objective of this work was to study the osmotic dehydration kinetics of melon pieces in two types of solution (sucrose and maltose), with simultaneous evaluation of texture and color parameters all along the process. Melon (Cucumis melo inodorus, cultivar Gold Mine) cubes of 20 mm were immersed in hypertonic solution of sucrose or maltose with different concentrations (40 to 60°Brix) and the process was carried out for eight hours under controlled temperature (30°C or 40°C) and agitation (120 rpm). Water and weight loss, solids gain, water activity, color and texture were analysed throughout the process as a function of temperature, osmotic agent and solution concentration. The final equilibrium point and the diffusion coefficients for water and sugar were estimated using an empiric model from literature based on Fick's unsteady law of diffusion in order to compare sucrose and maltose effects in mass transfer rates during the osmotic process. For all treatments, water removal and weight loss increased at a significant level for higher temperature and solution concentrations, but the greatest water loss rate and lowest sugar uptake was verified when using maltose solutions. The color fresh-like characteristics were practically kept by the osmotic dehydration, with a slightly color intensification due to an increase on the b* parameter and on chrome values, as a consequence of fruit pigments concentration, caused by water loss. For the texture, an increase of viscous nature of fruit and elasticity loss was observed, indicating that the sugar impregnation occurred along the process provoked a plasticity in fruit structure. Maltose showed to be more effective on fruit texture maintenance. The best conditions for each one of the response variables were selected and the final product was evaluated by a sensorial analysis. The treatment time for these tests was two hours, determined by water loss, solids gain and texture kinetics. Sensorial results revealed that osmotic dehydration provided a good product acceptance by the consumer / Mestrado / Engenharia de Alimentos / Mestre em Engenharia de Alimentos

Orientador: Hilary Castle de Menezes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T04:09:07Z (GMT). No. of bitstreams: 1 Buchweitz_PauloRenato_D.pdf: 3265983 bytes, checksum: 57291d57e5ec02775a2fcdf1204dd61a (MD5) Previous issue date: 2005 / Resumo: Em algumas regiões do Brasil a cultura do kiwi encontrou bom potencial para o seu desenvolvimento. A cultivar Hayward destaca-se pela produção de frutos com elevada qualidade no sabor, tamanho, conservação e valor nutricional. Até o momento a maioria das pesquisas pós-colheita esteve voltada a conservação pelo frio, em virtude da elevada susceptibilidade deste fruto a alterações físico-químicas e sensoriais decorrentes dos métodos convencionais de conservação. Este trabalho procurou avaliar os efeitos da pré-secagem osmótica em parâmetros de qualidade de fatias de kiwi secas, congeladas, liofilizadas e pasteurizadas. Os frutos para a execução dos experimentos foram adquiridos diretamente de pomar comercial localizado em Campos do Jordão-SP. Inicialmente foi realizada uma avaliação da pré-secagem osmótica de fatias de kiwi de 10-11mm de espessura sob condições de processo pré-estabelecidas: imersas em solução de sacarose a 65% a 40°C por 15, 60, 120, 180 e 240 minutos com agitação em shaker a 75 oscilações horizontais e amplitude de 1cm, utilizando fruta em solução de sacarose na proporção de 1:4. Os produtos obtidos foram avaliados sensorialmente e verificou-se que a condição correspondente a duas horas de processo foi a melhor aceita, sendo este resultado posteriormente considerado no estudo dos métodos convencionais. Na secagem com circulação forçada de ar aquecido a 40°C até 25% de umidade residual a pré-secagem osmótica proporcionou em média uma redução de 10% no tempo necessário ao processo e melhor aparência, aroma característico e maior firmeza das fatias após a reconstituição com água e açúcar. No estudo do osmo-congelamento por meio da avaliação dos métodos de congelamento por ar estático, contato em placas ou imersão em nitrogênio líquido, foi constatado que a prévia desidratação osmótica exerceu maior influência do que os diferentes métodos de congelamento nos níveis estudados na redução do líquido exsudado e no aumento da firmeza após o descongelamento. O tratamento prévio também contribuiu para melhorar a aparência geral e intensificar a coloração esverdeada. Na avaliação dos efeitos dos referidos métodos de congelamento nos experimentos de osmo-liofilização foi observado que o tratamento prévio em solução de sacarose não promoveu redução no tempo necessário à liofilização. No entanto, proporcionou melhora na textura e coloração das fatias, enquanto que a quantidade de água reincorporada às fatias foi mais influenciada pelos métodos de congelamento. Os produtos em calda processados com fatias submetidas a pré-secagem osmótica apresentaram aceitação sensorial similar quanto ao aroma e sabor e aceitação melhor quanto a aparência e textura durante o armazenamento, comparativamente aos produtos processados com fatias não submetidas ao tratamento prévio. O aproveitamento do xarope da pré-secagem osmótica como líquido de cobertura pode contribuir para a redução de custos no envase de fatias de kiwi em calda / Abstract: Mastitis is an inflammatory reaction of the mammary gland, caused by pathogenic bacteria, resulting in increased number of somatic cells of milk. Milks with high somatic cells count (SCC) present alterations in the composition, influencing, therefore, the quality of processed dairy products. The objective of this work was to evaluate the effect of milk SCC on the development of microorganisms and sensorial characteristics, during ripening of Prato cheese. Two groups of animals were selected to obtain milk with low (< 200.000 cell/ml) and high (> 700.000 cell/ml) SCC. Centesimal composition of cheeses was evaluated after processing and after 6, 12, 19, 35 e 54 days of storage for lactic bacteria, psychrotrophs, total bacteria count, yeasts and moulds counts. A factorial arrangment of treatments 2 x 5 in a completely randomized blocks was used. The effect of SCC (2 levels of variation) and storage time (5 levels of variation) on studied variables was evaluated by ANOVA and Tukey?s test at 5% of significance. The cheeses sensory evaluation was carried out through firmness, flavor and of lavors using ideal scale of nine points and general acceptance was evaluated by hedonic scale of nine points. The sensory evaluations were carried out after 7, 21, 34, 48 and 61 days of storage. Milk with high SCC had higher pH than milk with low SCC. Cheeses obtained from high SCC milk showed higher moisture than cheeses with low SCC. SCC affected lactic bacteria and psychrotrophs counts, as higher levels were found in low SCC cheeses. Total count bacteria, lactic acid and psychrotrophs counts decreased during storage, while yeasts and moulds count increased, independently of milk SCC. The sensory evaluation showed lower general acceptance to high SCC cheeses when compared with low SCC cheeses / Doutorado / Tecnologia de Alimentos / Doutor em Tecnologia de Alimentos

Orientador: Fernanda Elizabeth Xidieh Murr / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T14:06:18Z (GMT). No. of bitstreams: 1 El-Aouar_AnoarAbbas_D.pdf: 8511709 bytes, checksum: cba4d746e13aa67d8ce921d71aa5681b (MD5) Previous issue date: 2005 / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos

Dans le but de protéger la levure Saccharomyces cerevisiae pendant la déshydratation, deux stratégies ont été envisagées pour améliorer la survie cellulaire. D’une part, le renforcement de la résistance à l’oxydation (protection interne) a été réalisé par l’enrichissement en glutathion intracellulaire de la levure. D’autre part, l’encapsulation par la méthode couche-par-couche (layer-by-layer) en utilisant deux biopolymères β-lactoglobuline et alginate a été utilisée pour la protection externe de la levure. Un milieu adéquat ainsi que des conditions favorables de culture permettant l’enrichissement en glutathion intracellulaire ont été déterminés. La composition du milieu est riche en nutriments et précurseurs du glutathion se composant de 30 g/L de glucose, 30 g/L d’extrait de levure, 0,6 g/L de KH2PO4 et 0,6 g/L de cystéine. Le succès de l’encapsulation a été confirmé par différentes méthodes d’analyse comme la zétamétrie, la microscopie électronique et la spectroscopie infrarouge. Le dépôt des trois couches de β-lactoglobuline/alginate/β-lactoglobuline n’a pas affecté l’intégrité membranaire et la croissance de la levure. De plus, la perméabilité membranaire n’a pas été empêchée par la présence de cette barrière biopolymérique. L’effet de l’enrichissement en glutathion et de l’encapsulation sur la résistance de la levure dans les conditions de déshydratation choisies a été mesuré par l’estimation de la survie, les modifications biochimiques et le métabolisme des cellules. Les résultats ont montré que la levure enrichie en glutathion présente une meilleure survie après la déshydratation. De plus, la survie de la levure est améliorée par l’encapsulation, en particulier pendant la déshydratation à 45 °C. L’analyse des résultats d’infrarouge a relevé un point commun dans la relation entre les propriétés biochimiques de la cellule et la survie cellulaire. Plus le groupement méthyle (CH3) est important, plus la survie est importante. Le rôle du glutathion dans la protection de la levure a également été mis en évidence pendant la déshydratation. Il semblerait que l’action du glutathion oxydé ait été mise en place après l’intervention du glutathion réduit. De plus, la protection interne par le glutathion a permis à la levure de résister au stress chimique alors que la protection externe par encapsulation renforce la résistance contre les stress physique ou mécanique. Les résultats de la thèse pourront être utiles pour la recherche des nouvelles technologies de production et de protection des levures fragiles actives. / In order to protect the Saccharomyces cerevisiae yeast during dehydration, two strategies were used to improve cell survival. Strengthening cell resistance (internal protection) was performed by improving the concentration of intracellular glutathione in yeast. Encapsulation was performed by layer-by-layer method using two biopolymers β-lactoglobulin and alginate for the external protection of the yeast. The adequate medium culture and favorable growing conditions for glutathione enhancement were determined. The composition of the culture medium is rich in nutrients and glutathione precursors consisting in 30 g/L glucose, 30 g/L yeast extract, 0.6 g/L KH2PO4 and 0.6 g/L cysteine. The success of encapsulation was confirmed by different analytical methods such as zetametry, electron microscopy and infrared spectroscopy. The deposition of three layers of β-lactoglobulin/alginate/β-lactoglobulin did not affect membrane integrity and the growth of yeast. Furthermore, the membrane permeability was not affected by the presence of this biopolymer barrier. The effect of glutathione and encapsulation on the resistance of the yeast in dehydrating conditions was measured by the estimation of cell survival, biochemical modification and cellular metabolism. The results showed that the glutathione-enriched yeast present higher survival after dehydration. Moreover, the survival of the yeast was improved by the encapsulation. These observations were clearly obtained in dehydration conditions at 45 °C. Infrared analysis identified a common point in the relationship between biochemical property and cell survival. Higher survival was observed when the yeast was characterized by methyl group (CH3). The role of glutathione in yeast protection was highlighted during dehydration. It seemed that the action of oxidized glutathione was set up after the intervention of reduced glutathione. In addition, the internal protection by glutathione allowed the yeast to resist to chemical stress while the external protection by encapsulation enhances the resistance against physical or mechanical stress. These results can be useful for the research of new technology in fragile yeast production and protection.

Les séismes intermédiaires (30-300 km) ont été largement documentés dans les plaques océaniques en subduction mais leur mécanisme physique reste énigmatique. Des séismes se produisent dans les plans de Wadati-Bénioff supérieur et inférieur. Ce dernier se situe dans le manteau lithosphérique plongeant, 15 à 40 km sous l’interface de subduction, et est considéré dû à la déshydratation de l’antigorite, serpentine de haute température.Pour tester cette hypothèse et comprendre quel mécanisme est en jeu dans le plan inférieur, des expérimentations (Griggs et D-DIA) et une étude de terrain (Balmuccia, Italie) ont été effectuées.Des péridotites artificielles ont été déshydratées pendant leur déformation dans des conditions typiques du manteau supérieur (1 à 3.5 GPa). Des émissions acoustiques sont enregistrées dans des échantillons comportant 5 %vol. d’antigorite. Les microfailles associées sont scellées par des pseudotachylites contenant des fluides, montrant que la déstabilisation de l’antigorite a déclenché une rupture dynamique et la fusion de l’olivine sur la surface de faille. Ces résultats mènent à l’établissement d’un model dans lequel un transfert de contrainte induit par déshydratation, et non par surpression de fluides, est le déclencheur de la fragilisation des roches du manteau.Parallèlement, une pseudotachylite de la péridotite de Balmuccia révèle l’enregistrement de l’histoire du glissement d’un séisme fossile de magnitude Mw > 6. La lubrification co-sismique est complète et transitoire, car le magma peut rapidement s’écouler dans les fentes en tension lors du passage du front de rupture, peut-être plus vite qu’il n’est produit. L’aspiration du magma mènerait à un refroidissement permettant le rétablissement de la résistance et l’arrêt du glissement.Cette pseudotachylite naturelle, un million de fois plus grande que son analogue expérimental, s’est formée dans les mêmes conditions de pression et de température. La grande similitude entre ces failles sur le terrain et au laboratoire indique un mécanisme similaire, et donc que les expériences montrent un mécanisme de rupture représentatif de ce qui se passe dans la nature. D’autre part, de l’H2O, trouvée fossilisée dans la pseudotachylite, était présente pendant la rupture sismique.Ce travail réconcilie des décennies d’études semblant contradictoires sur le lien entre séismes mantelliques et déshydratation de l’antigorite. À une certain échelle, une fraction d’antigorite de seulement 5 %vol. suffit à déclencher une sismicité, qui pourrait finalement être vue comme un indicateur du degré d’hydratation dans le manteau lithosphérique. / Intermediate-depth earthquakes (30-300 km) have been extensively documented within subducting oceanic slabs but their physical mechanisms remain enigmatic. Earthquakes occur both in the upper and lower Wadati-Benioff planes. The latter is located in the mantle of the subducted oceanic lithosphere, 15-40 km below the plate interface, and is thought to be due to the dehydration of antigorite, the high-temperature serpentine.To test this hypothesis and understand which mechanism is at play in the lower plane, both experiments (Griggs and D-DIA) and field work (Balmuccia, Italy) have been performed.Artificial peridotites were dehydrated during deformation at upper mantle conditions. Between 1 and 3.5 GPa, acoustic emissions are recorded in samples with only 5 vol.% antigorite. Associated microfaults are sealed by fluid-bearing pseudotachylytes, showing that antigorite destabilization triggered dynamic shear failure and frictional melting of olivine. These results lead to a model in which dehydration-induced stress transfer, rather than fluid overpressure, is the trigger of mantle rocks embrittlement.Simultaneously, a pseudotachylyte from the Balmuccia peridotite reveals the recorded sliding history of an ancient Mw > 6 earthquake. The co-seismic fault lubrication is complete and transient, as the melt could rapidly flow into tensile fractures generated by the rupture front pass through, possibly faster than it is produced. Melt suction within the fractures led to rapid cooling and may have promoted strength recovery and sliding arrest.This natural pseudotachylyte, one million times larger than the experimental ones, has formed at the same pressure and temperature. The high similarity between those experimental and natural faults indicates a similar mechanism at both scales, and thus that the experiments show a rupture mechanism representative of what happens in nature. Furthermore, H2O, found fossilized in the pseudotachylyte, was somehow present during the seismic rupture.This work reconciles decades of apparently contradictory studies on the possible link between mantle earthquakes and serpentine dehydration. At a certain scale, an antigorite fraction as low as 5 vol.% is sufficient to trigger seismicity, which could therefore ultimately be seen as an indicator for the degree of hydration in the lithospheric mantle.

Les années 1990 ont été marquées par le développement de la Chimie Verte avec les premiers travaux sur le sujet et l’introduction des Douze Principes. Depuis, le nombre de recherches sur la Chimie Verte n’a cessé de croître. Ces travaux de thèse portent sur le développement de méthodes de déshydratation dans le but de former des molécules à haute valeur ajoutée en utilisant les Douze Principes de la Chimie Verte en tant que ligne directrice. Deux molécules cibles ont été sélectionnées : (i) le phénylacétaldéhyde, obtenu par déshydratation du 1-phényléthane-1,2-diol, qui est utilisé dans la composition de parfums, de médicaments, d’insecticides, etc., ou en tant qu’intermédiaire réactionnel ; et (ii) le furfural, formé par la triple déshydratation du D-xylose (monomère principal des hémicelluloses), qui peut être utilisé comme solvant sélectif ou comme molécule plateforme pour produire une large gamme de composés d’intérêt. Plusieurs points-clés ont été identifiés pour concevoir des procédés de déshydratation verts: le solvant (l’eau ou le solvant éco-compatible CPME), la méthode d’activation (utilisation d’irradiation micro-ondes ou d’un réacteur en flux continu) et le catalyseur (chlorures de métaux ou résine échangeuse d’ions). / The 1990s have witnessed the development of Green Chemistry with the first researches on the subject and the introduction of the Twelve Principles. Since then, the number of scientific works on Green Chemistry has continuously grown. This PhD work focus on the development of dehydration methods to form high added value molecules by using the Twelve Principles of Green Chemistry as a guiding framework. Two target molecules were selected: (i) phenylacetaldehyde, obtained by the dehydration 1-phenylethane-1,2-diol, which is used in perfume compositions, for the preparation of pharmaceuticals, insecticides, etc., or as a chemical intermediate; and (ii) furfural, formed thanks to the triple dehydration of D-xylose (the main sugar unit of hemicellulose), which can be used as a selective solvent or as a platform molecule to produce a wide range of high-value chemicals. The optimisation of green production processes was focused on several key points: solvents (water and the eco-friendly CPME), activation method (microwave irradiation and continuous flow) and catalysis (metal chlorides and ion-exchange resin).

L'acrylate d'éthyle est synthétisé par l'estérification catalytique de l'acide acrylique et de l'éthanol. La réaction s'écrit : CH2=CH-COOH + C2H5OH D CH2=CH-COOC2H5 + H2O Comme cette réaction est équilibrée, l'élimination de l'eau produit par la réaction permet de déplacer la réaction, donc d'augmenter le taux de conversion de l'acide acrylique et la productivité en acrylate d'éthyle. La pervaporation est une technique de séparation membranaire, qui est potentiellement intéressante pour la déshydratation de mélanges organiques. Dans ce travail, nous avons étudié le procédé industriel de l'estérification de l'acrylate d'éthyle qui est continu. C'est la première fois que la pervaporation d'un mélange complexe contenant des dérivés acryliques polymérisables est étudiée. Tout d'abord le procédé continu d'estérification a été simulé sur Aspen Plus. Une analyse du schéma de procédé a permis d'identifier deux scénarii d'amélioration des performances énergétiques par pervaporation. Dans le scénario le plus favorable, la pervaporation permet de réduire de 25% la consommation d'énergie ou d'augmenter de 25% la production. Dans la deuxième partie de notre étude, des membranes commerciales ont été testées pour déshydrater des mélanges représentatifs du milieu d'estérification. Les membranes testées ont montrées de bonnes performances de séparation (flux et sélectivité élevées) et de bonnes résistances chimiques. La faisabilité de l'intégration de la pervaporation au procédé est donc prouvée / Ethyl acrylate is synthesized by the catalytic esterification of acrylic acid and ethanol. The reaction can be described as: CH2=CH-COOH + C2H5OH D CH2=CH-COOC2H5 + H2O Since this reaction is reversible, the removal of the water helps shifting the reaction to the right side, thus increasing the conversion of acrylic acid to ethyl acrylate. Pervaporation is a membrane separation technique which is helpful for the dehydration of organic mixtures. In this work, we studied the industrial process for the esterification of ethyl acrylate which is continuous. To our knowledge this is the first time that the pervaporation of a mixture containing polymerizable acrylic derivatives is studied. Firstly, the continuous esterification process was simulated on Aspen Plus. An analysis of the flowsheet diagram has identified two scenarios for improving energy performance through implementing dehydration pervaporation. In the most favorable scenario, the pervaporation can reduce 25% energy consumption or increase 25% ethyl acrylate production. In the second part of our study, commercial membranes were tested for dehydrating mixtures which are representative of esterification reaction. The tested membranes offered good separation performance (high flux and selectivity) and high chemical resistance. The feasibility of the hybrid process is thus proven

La conservation de microorganismes d’intérêt (ferments, probiotiques) sous forme sèche et revivifiable est très répandue dans l’industrie. Cependant, les procédés de déshydratation conduisent à des taux de survie variables en fonction du groupe, de l’espèce et de la souche de microorganismes considérée ainsi que du type de procédé utilisé (séchage, lyophilisation, congélation). La membrane plasmique (MP), de par sa position entre l’environnement intra et extracellulaire, est une cible privilégiée des perturbations hydriques. Les modifications de cette structure lors de stress hydriques sont décrites pour être directement impliquées dans la mort des microorganismes. La compréhension des réponses membranaires se produisant pendant un cycle de déshydratation/réhydratation est essentielle afin d’optimiser la survie des microorganismes lors des procédés de déshydratation. Les manipulations réalisées lors de cette étude ont visé à caractériser les modifications fonctionnelles (intégrité) et structurales (déformations, répartition latérale de microdomaines riches en stérols) de la MP de Saccharomyces cerevisiae lors de différents types de perturbations hydriques (déshydratations osmotiques de différentes amplitudes et cinétiques, séchage dans différentes ambiances gazeuses). L’impact de la composition de la MP sur la survie des levures a également été étudié par l’utilisation de mutants accumulant différents types de stérols au niveau membranaire. Ce travail a confirmé la forte implication de la MP dans la mort des cellules lors de perturbations hydriques. L’étude des modifications membranaires a permis d’élucider le lien entre la cinétique de déshydratation et la survie des levures. Il a également été montré que l’ergostérol est une molécule clé dans la survie des levures aux perturbations hydriques. / Preservation of microorganisms of interest (ferments, probiotics) in dry form is widespread in the industry. However, the dehydration processes lead to variable survival rates according to the group, species and strain of microorganism considered, but also according to the type of process used (drying, freeze drying, freezing). The plasma membrane (PM), by its position between the intra-and extracellular environment, is a target of hydric perturbations. Changes in this structure during hydric stresses are described to be directly involved in microorganism death. Understanding of membrane responses occurring during a dehydration/rehydration cycle is essential to maximize the survival of microorganisms in the process of dehydration.Manipulations performed in this study aimed to characterize functional (integrity) and structural (deformations, lateral distribution of sterol-rich microdomains) changes of the PM of Saccharomyces cerevisiae during different types of hydric perturbations (osmotic dehydration of different magnitudes and kinetics, drying in different gas atmospheres). The impact of the composition of PM on yeast survival was also studied by using mutants accumulating different types of sterols in membranes. This work confirmed the strong involvement of the PM in cell death during hydric perturbations. The study of membrane changes helped to elucidate the relationship between the kinetics of dehydration and survival of yeasts. It has also been shown that ergosterol is a key molecule for the survival of yeasts during hydric perturbations.

Orientador: Rubens Maciel Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-18T17:35:35Z (GMT). No. of bitstreams: 1 Fonseca_NatalieAlexandraAmezquita_M.pdf: 1706178 bytes, checksum: 6e4b89c3e1712bb8a16be86c7a7f01bc (MD5) Previous issue date: 2011 / Resumo: Um dos problemas na produção de etanol é o elevado custo energético associado a sua separação por causa do excesso de água e a existência de um azeótropo na mistura etanol - água, pelo que através da destilação convencional esta mistura só pode ser separada até um máximo de 95% em peso. Existe na atualidade um notável interesse no desenvolvimento de processos tecnológicos com o objetivo de melhorar as técnicas de separação necessárias para isolar o etanol do produto obtido na fermentação. Convencionalmente as técnicas empregadas para a purificação final na etapa posterior à destilação convencional são a destilação azeotrópica e a destilação extrativa, embora a importância relativa da adsorção tenha aumentado nos últimos anos como conseqüência do desenvolvimento dos processos de adsorção, a invenção das peneiras moleculares. Desta forma o processo PSA (Pressure Swing Adsorption) como um processo de maior eficiência térmica tornou se uma alternativa à destilação azeótropica. No entanto, o desenho e a análise de um sistema PSA é uma tarefa difícil devido ao grande número de parâmetros envolvidos na simulação numérica, pelo que é de grande importância a utilização de simuladores comerciais no estúdio deste tipo de processos. No presente trabalho foi estudada a dinâmica do processo PSA para a desidratação de etanol com zeólitas 3A mediante sua simulação no Software comercial Aspen Adsim. Foram estimados a partir de dados experimentais encontrados na literatura os parâmetros da Isoterma de Langmuir e o coeficiente de transferência de massa dado por LDF e estabelecido o ciclo de Adsorção PSA completo. As condições utilizadas foram similares as indústrias e foram estabelecidos ciclos por médio da ferramenta Cycle Organizer do simulador com 4 passos básicos assim: Adsorção, Despressurização, Purga e Pressurização em um tempo total de 11,5 minutos para dois leitos de adsorção. Foi atingido um estado estável CSS ao redor de 383 ciclos com uma pureza de 99,4%, 92,9% de recuperação e 46,83 l/hr/kg de produtividade. Foram pesquisados os efeitos da pressão de adsorção, a concentração da água na alimentação e vazão de alimentação, assim com a influência dos parâmetros da isoterma de Langmuir e do coeficiente de transferência de massa MTC para dois leitos de adsorção sob a Porcentagem de Pureza, Recuperação e Produtividade. Mediante este análise foi possível verificar que todas as variáveis de processo estudadas são significativas nas variáveis de resposta, enquanto constatou se que o parâmetro MTC é um parâmetro sensível que depende do sistema e das resistências que atuam no momento da transferência de massa, pelo que tem que ser estimado a partir de dados experimentais. Os efeitos das variáveis de projeto diâmetro e comprimento da coluna influíram notoriamente na produtividade do processo.Em conclusão o simulador Aspen Adsim tem sido apresentado como uma ferramenta útil para simulação dinâmica de um processo de adsorção / Abstract: One of the problems with ethanol production is the high energy cost which is associated with the separation of ethanol due to of excess water and the existence of an azeotrope in the mixture ethanol-water, by conventional distillation the mixture can be separated up to 95% weight. Currently, there is great interest in the development of technological processes to improve the necessary separation techniques in order to isolate the product obtained in ethanol fermentation. Conventionally, the techniques employed for final purification after conventional distillation are azeotropic distillation and extractive distillation. Although the relative importance of adsorption processes has increased in recent years as a result of increased development of adsorption process and the invention of molecular sieves. Thus, the PSA (Pressure Swing Adsorption) technique as a process of improved thermal efficiency has become an alternative in the azeotropic distillation. However, the design and analysis of a PSA system represents a difficult task due to the large number of parameters involved in the numerical simulation. Therefore, it is of great importance the commercial use of simulators in this research process. This study analyzed dynamics of the PSA process for the dehydration of ethanol with zeolite 3A by means of its commercial simulator software Aspen Adsim. It estimated that the parameters of the Langmuir isotherm and mass transfer coefficient given by LDF based on experimental data from the literature, furthermore, it established the complete PSA adsorption cycle. The conditions were similar to those used in the industry and have been established by means of the simulator, Cycle Organizer tool, the following for basics steps: adsorption, depressurization, purge and pressurization in a total time of 11,5 min to two adsorption beds. A steady state was reached - CSS around 383 cycles, with a purity of 99.4%, 92.9% of recuperation and 46.83 l/hr/kg of productivity. A parametric study also was done to investigate the effects of adsorption pressure, the concentration of water in food, feed flow, the of the Langmuir isotherm parameters and mass transfer coefficient - MTC for two adsorption beds under the percentage of purity, recovery and productivity. Through this analysis it was verified that all processes variables are significant in the studies response variables. While the MTC parameter found that is a susceptible parameter and depend on the resistances of transfer and, therefore, has to be estimated from experimental data. The effects of design variables such as diameter and length of bed visibly influenced the productivity of this process. In conclusion the simulator Aspen Adsim has been presented as a useful tool for dynamic simulation of adsorption process / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

O pólen além de ser a principal fonte de alimento não líquido, para as abelhas, tem sido utilizado como um suplemento da dieta humana. Apesar de muitos autores afirmarem que os produtos apícolas são ricos em nutrientes, pouco se sabe sobre a composição do pólen apícola especialmente em relação à presença das vitaminas do complexo B. De forma original este estudo teve por objetivo avaliar a estabilidade das vitaminas do complexo B (B1, B2, B6 e PP) incluindo seus vitâmeros, durante o período de um ano de estocagem, em amostras de pólen apícola desidratado. Verificou-se também o efeito do processamento sobre o conteúdo dessas vitaminas além da possível influência dos tipos polínicos sobre a composição centesimal e conteúdo vitamínico. Foram analisadas concentrações das vitaminas no tempo zero e após 4, 8 e 12 meses, estocadas sob três condições distintas: em temperatura ambiente (com e sem exposição à luz) e em freezer. As vitaminas, após a extração simultânea, foram quantificadas por CLAE, com detecção por fluorescência. Todas as vitaminas propostas foram encontradas nas amostras analisadas e o processo de desidratação não interferiu no conteúdo das mesmas (p<0,05). As variações foram (base seca): 0,59 a 1,09 mg/100g para vitamina B1; 1,73 a 2,56 mg/100g para a vitamina B2; 6,43 a 15,34 mg/100g para a vitamina PP e 0,33 a 0,68 mg/100g para a vitamina B6 . Todas as amostras foram classificadas como pólen heterofloral, em função da grande variabilidade dos tipos polínicos presentes. Após um ano de estocagem pode-se afirmar que a concentração da vitamina B1 se manteve constante enquanto que para as demais vitaminas o decaimento da concentração foi dependente do tempo de armazenamento e não da condição de estocagem das amostras (p<0,05). Todas as amostras foram consideradas fonte da vitamina B2. Foi possível explicar matematicamente, através de equações de regressão linear oriundas da análise multivariada, a influência do tempo de armazenamento nas concentrações das vitaminas B6 e PP, com explicabilidade de 76 e 60% respectivamente. / Pollen is the main source of non liquid food for bees and it has been used as a supplement for human diet. Although many authors cited that bee products are rich in nutrients, it is known a little about the composition of bee pollen and, in particular, the presence of the B vitamin complex in this product. This original study has the objective of evaluate the stability of B complex vitamins (B1, B2, B6 and PP), including its vitamers for a period of one year of storage in dried samples of bee pollen. It was also analyzed the effect of processing on vitamin content and the possible influence of polinic types on proximate composition and vitamin content. Samples were analyzed at time zero, after 4, 8 and 12 months. They were storaged under three different conditions: room temperature (with and without exposure to light) and freezer. The vitamins were quantified by HPLC with fluorescence detection after simultaneous extraction. All proposed vitamins were found in the analyzed samples and the dehydration process did not interfere in vitamin content (p<0.05). The variations were (dry basis): 0.59 to 1.09 mg/100g for vitamin B1; 1.73 to 2.56 mg/100g for vitamin B2; 6.43 to 15.34 mg/100g for vitamin PP and 0.33 to 0.68 mg/100g for vitamin B6. All samples were classified as heterofloral pollen, according to the big variability of polinic types. After one year of storage, it can be stated that vitamin B1 concentration remained constant, while for the other vitamins, the concentration loose was dependent on time and not on the storage condition (p<0.05). All samples were considered Vitamin B2 source. It was possible to explain mathematically, through linear regression equations of multivariate analysis, the influence of storage time in the concentrations of vitamin B6 and PP, they were explained as 76 and 60% respectively.