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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Este trabalho teve como objetivo estudar a qualidade de bife bovino processado em escala industrial atravÃs de tecnologia sous vide durante as etapas sequenciais do processo. Foram realizadas anÃlises fÃsico-quÃmicas e microbiolÃgicas em bife de MÃsculo bovino Supraspinatus in natura, temperado e processado por tecnologia sous vide (80ÂC/5horas) e armazenados a 3ÂC durante 0, 15, 30, 45 e 60 dias, para estudo da estabilidade. Foi ainda realizada avaliaÃÃo sensorial dos bifes durante armazenamento a 0 e 30 dias a 3ÂC para verificaÃÃo da aceitaÃÃo quanto a cor, aroma, sabor, suculÃncia, textura, impressÃo global e atitude de compra. O estudo da estabilidade dos bifes bovinos sous vide permitiu observar poucas alteraÃÃes para os parÃmetros de cinzas, proteÃna, a*, b*, Chroma, Hue e nenhuma alteraÃÃo para os parÃmetros L*, umidade e gordura no decorrer do tempo de armazenamento por 60 dias a 3ÂC. NÃo houve diferenÃa significativa (p<0,05) entre as amostras para caracterÃsticas de sabor, suculÃncia, textura e impressÃo global, contudo houve diferenÃa significativa (p>0,05) dos parÃmetros de cor e aroma. As respostas para a intenÃÃo de compra mostraram que os consumidores classificaram as amostras prÃximo ao termo hedÃnico (4) correspondente a âprovavelmente comprariaâ, nÃo havendo diferenÃa significativa (p>0,05%) entre as amostras. Foram encontradas contagens de aerÃbios mesÃfilos, coliformes fecais e coliformes totais no bife bovino in natura, bife bovino temperado e presenÃa de Listeria monocytogenes em uma das cinco coletas de bife in natura, contudo estes micro-organismos nÃo foram encontrados em nenhuma das amostras submetidas à tecnologia sous vide e durante estudo de estabilidade. Foram detectados esporos de aerÃbios e anaerÃbios nos bifes sous vide durante armazenamento. Desta forma, o tratamento (80ÂC/5 horas) nÃo à suficiente para tornar o alimento isento de micro-organismos capazes de se reproduzir no produto em condiÃÃes de estocagem nÃo refrigerada. O cozimento sous vide proporcionou um produto final com uma maior retenÃÃo de nutrientes (proteÃna, gordura). O armazenamento por 30 dias a 3ÂC parece nÃo ter contribuÃdo para a alteraÃÃo das caracterÃsticas sensoriais das amostras. Isto indica que os bifes sous vide podem ser armazenado com sucesso atà a 30 dias a 3ÂC e ser de qualidade sensorial aceitÃvel para os consumidores. Os resultados deste estudo confirmam o potencial tecnolÃgico do mÃsculo Supraspinatus para a elaboraÃÃo de bife sous vide, e sua viabilidade de produÃÃo e comercializaÃÃo para consumo humano. De uma forma geral, o bife sous vide manteve suas propriedades ao longo do armazenamento, sendo uma excelente fonte de nutrientes, principalmente no que se refere ao teor de proteÃna. A tecnologia sous vide apresenta-se como uma excelente alternativa para o mercado de carne, por agregar valor ao produto e conservar suas caracterÃsticas de qualidade. / The aim of this study was to verify the quality of steak cattle processed in industrial scale using sous vide technology during the sequential steps of the process. Physico-chemical and microbiological analysis were performed with the bovine muscle steaks Supraspinatus in natura, Steaks were spicy and processed by sous vide technology (80ÂC/5 hours) and stored at 3ÂC for 0, 15, 30, 45 and 60 days for stability studies. It was also performed sensory evaluation of steaks during storage at 0 and 30 days at 3  C to verify the acceptance and the color, aroma, flavor, juiciness, texture, overall impression and attitude of purchase. The stability of sous vide bovine steak allowed to observe a few changes in parameters such as ash, protein, a *, b *, Chroma, Hue, and no changes in L *, moisture and fat during the storage time for 60 days at 3ÂC. There was no significant difference (p <0.05) between the characteristics of samples for flavor, juiciness, texture and overall impression, however significant difference (p> 0.05) was achieved for color and aroma. The responses for purchase intent showed that consumers rated the samples near the hedonic term (4) corresponding to "I would probably buy", with no significant difference (p> 0.05%) between samples. There were counts of aerobic mesophilic, coliform and fecal coliforms in natura steak, steak seasoned and Listeria monocytogenes in one of five collections of in natura steak, but these microorganisms were not found in any sample submitted to sous vide technology and for stability studies. Spores were detected in aerobic and anaerobic sous vide steak during storage. Thus, treatment (80 ÂC/5 hours) is not sufficient to make the food free of microorganisms capable of reproduction in the product in non-refrigerated storage conditions. Cooking sous vide a final product provided with a greater retention of nutrients (proteins, fat). The storage for 30 days at 3ÂC seems to have contributed to the change of the sensory characteristics of the samples. This indicates that the sous vide steaks may be stored successfully for 30 days at 3ÂC and sensory quality can be acceptable to consumers. The results of this study confirm the technological potential of the Supraspinatus muscle for the preparation of steak sous vide, and the viability of its production and marketing for human consumption. In general, the steak sous vide kept its properties during the storage, being an excellent source of nutrition, especially in regard to protein content. The sous vide technology presents itself as an excellent alternative to the meat market by adding value to the product and maintain their quality characteristics

Après une dizaine d'années de recherche dans le domaine de la modélisation des plasmas froids hors-équilibre, j'ai souhaité synthétiser les principaux résultats obtenus durant cette période dans le domaine de la propulsion à plasma en vue de l'obtention de mon Habilitation à Diriger des Recherches. Je présente également dans ce document quelques pistes intéressantes à investiguer dans le domaine de la propulsion à plasma au sens large. J'ai choisi de diviser le document en trois parties distinctes, la première synthétise mes activités de recherche et présente les grandes lignes de mon projet de recherche, la seconde regroupe un certain nombre d'informations complémentaires me concernant, la dernière regroupe les publications les plus significatives. Je tiens à exprimer ma plus profonde gratitude à tous les étudiants dont j'ai encadrés les travaux de recherche ainsi qu'à l'ensemble de mes collègues pour toutes les discussions fructueuses et conseils prodigués tout au long de cette période. Je tiens également à remercier chaleureusement l'ensemble des membres du jury pour avoir examiné mes travaux. Je vous souhaite une bonne lecture !

Thèse de doctorat : Sciences et ingénierie des matériaux : Vandoeuvre-les-Nancy, INPL : 2006. / Titre provenant de l'écran-titre. Bibliogr.

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Ce projet de recherche s’est intéressé à la modélisation fine du transport d’espèces gazeuses en régime moléculaire en vue de l’appliquer à des technologies de dépôt sous vide poussé (VP), et plus particulièrement à la technique d’épitaxie par jets chimiques (ÉJC). Un modèle spécifique a été établi et une méthode de calcul a été implémentée sous la forme d’un logiciel MATLABTM. Les profils angulaires de densité de flux obtenus via le logiciel ont été comparés à ceux mesurés à l’aide d’un banc de test mis au point durant ce projet. Le banc de test est constitué d’une chambre à VP dans laquelle on peut conditionner et faire circuler un gaz neutre à travers un injecteur et mesurer avec précision les flux émis le long d’un arc de cercle. Un excellent accord entre les distributions de densité de flux simulée et mesurée a été obtenu pour chacun des injecteurs testés lorsque le débit utilisé était suffisamment faible. Pour des débits plus forts, une dégradation progressive de l’accord entre mesures et simulations a été observée de façon systématique. Les profils de densité de flux tendent à s’aplatir et à s’élargir et les zones anguleuses à s’émousser, puis à s’arrondir. Cette évolution est attribuée à la perte graduelle du régime moléculaire dans l’injecteur. Cela impose donc une limite haute, liée à la géométrie de l’injecteur, sur le débit utilisable dans le cadre du modèle choisi. Le logiciel ainsi validé a été utilisé pour étudier les performances d’un injecteur tronc-conique émettant vers un disque (substrat) en fonction de la géométrie d’injection (dimensions de l’injecteur et configuration spatiale source-cible). Les critères de performances étaient, en premier, l’uniformité des flux sur le substrat, et ensuite, la fraction des flux atteignant la cible (efficacité d’injection). Plusieurs géométries d’injection optimales ont été trouvées aussi bien pour un disque fixe que pour un disque en rotation autour de son axe. Néanmoins, pour la plupart d’entre elles, une sévère limite sur le débit est imposée par la nécessité de maintenir le régime moléculaire dans l’injecteur. Au vu de ces résultats, il est suggéré de se tourner vers des géométries d’injecteur présentant de plus fortes conductances ou bien d’utiliser ou de développer un logiciel de simulation applicable au régime de transition.

Pumpkin is a vegetable that has a remarkable nutritional importance, especially because it is a rich source of carotenoids, the essential compounds to human nutrition. Although the cooking methods may influence the retention of nutrients and phytochemicals in foods, there is a need to know the best way to promote cooking in pumpkin, minimizing the significant nutritional and sensory loss. This study aimed to determine and compare the quality attributes of fresh pumpkin, achieved by different cooking methods: boiling, steam, vacuum (sous-vide) and microwave. It was made chemical and physico-chemical determinations, staining, functional constituents and microbiological and sensory analysis of the products. At the end of the study, it was found that the parameters of soluble solids, non-reducing sugars, total sugars, soluble dark pigments, hue angle, total anthocyanins, yellow flavonoids, carotenoids and phenolic compounds, and the sensory attributes of flavor, texture, overall impression and purchase intention presented significant variations for the effect of the performed cooking methods. The color of cooked samples was less bright (L*), red (a*) and yellow (b*) than the color of the fresh sample. The loss of vivid colors (reduction of chroma) over the fresh pumpkin was observed for all cooked samples. All cooking methods reduced the content of ascorbic acid, anthocyanins and total polyphenols. Total carotenoids ranged from 8,933.92 to 24,772.72 mg 100 g-1 of fresh sample, and 24.58% higher in cooking in microwave and 2.26% cooking in boiling, while the cooks in the steam and in vacuum (sous-vide) caused a reduction. The yellow flavonoids were more preserved for cooking in microwave and ranged from 9.31 to 13.73 mg 100 g-1 between the brews made. The sous-vide cooking caused the greatest loss of functional components, being attributed to increased cooking time and degradation by light. The products showed no microbiological contamination. The cooking in microwave showed the highest scores for all sensory attributes evaluated. The other three cooking were also well accepted by panelists, representing different market niches. Pumpkin has many quality attributes, with high levels of functional components, and cooking in microwave oven is the preferred method to promote their cooking. / A abÃbora à um legume que apresenta uma notÃvel importÃncia nutricional, destacando-se pelo fato de ser uma rica fonte de carotenÃides, compostos imprescindÃveis na nutriÃÃo humana. Todavia, os mÃtodos de cocÃÃo podem influenciar a retenÃÃo de nutrientes e fitoquÃmicos em alimentos, havendo a necessidade de se conhecer a melhor forma de promover a cocÃÃo em abÃbora, minimizando as significativas perdas nutricionais e sensoriais. Este trabalho objetivou determinar e comparar os atributos de qualidade de abÃbora in natura e obtida por diferentes mÃtodos de cocÃÃo: ebuliÃÃo, vapor, vÃcuo (sous-vide) e micro-ondas. Foram realizadas determinaÃÃes quÃmicas e fÃsico-quÃmicas, coloraÃÃo, constituintes funcionais e anÃlises microbiolÃgicas e sensoriais dos produtos. Ao final do estudo, constatou-se que os parÃmetros de sÃlidos solÃveis, aÃÃcares nÃo redutores, aÃÃcares totais, pigmentos escuros solÃveis, Ãngulo hue, antocianinas totais, flavonÃides amarelos, carotenÃides totais e polifenÃis totais, e os atributos sensoriais de sabor, textura, impressÃo global e intenÃÃo de compra apresentaram variaÃÃes significativas pelo efeito dos mÃtodos de cocÃÃo realizados. A cor das amostras cozidas foi menos brilhante (L*), vermelho (a*) e amarelo (b*) do que a cor da amostra in natura. A perda de cores vivas (diminuiÃÃo de croma) em relaÃÃo à abÃbora in natura foi observada para todas as amostras cozidas. Todos os mÃtodos de cocÃÃo reduziram os conteÃdos de Ãcido ascÃrbico, antocianinas totais e polifenÃis totais. Os carotenÃides totais variaram de 8.933,92 a 24.772,72 Âg 100 g-1 de amostra fresca, sendo elevados em 24,58% na cocÃÃo em micro-ondas e em 2,26% na cocÃÃo em ebuliÃÃo, enquando as cocÃÃes no vapor e no vÃcuo (sous-vide) provocaram reduÃÃo. Os flavonÃides amarelos foram mais preservados na cocÃÃo em micro-ondas e variaram de 9,31 a 13,73 mg 100 g-1 entre as cocÃÃes realizadas. A cocÃÃo sous-vide ocasionou as maiores perdas de componentes funcionais, sendo atribuÃdas ao maior tempo de cocÃÃo e a degradaÃÃo pela luz. Os produtos nÃo apresentaram contaminaÃÃes microbiolÃgicas. A cocÃÃo em micro-ondas foi a que apresentou maiores mÃdias para os atributos sensoriais avaliados. As outras trÃs cocÃÃes tambÃm foram bem aceitas pelos provadores, representando nichos diferenciados de mercado. A abÃbora possui muitos atributos de qualidade, apresentando elevados nÃveis de componentes funcionais, sendo a cocÃÃo em micro-ondas o mÃtodo preferido para promover a sua cocÃÃo.

The carrot is a crop rich in carotenoids, pro-vitamin A, minerals and carbohydrates, and is a food with high nutritional value. Brazil is among the five largest producers and consumers of carrot (Daucus carot L .) in the world, concentrating its production in the Southeast. In search of products more attractive, practical, nutritious and healt hy, the consumer's sous vide technology is an alternative technology for the industry in providing food ready for consumption. The sous vide consists in cooking food packaged in plastic vacuum -sealed, subjected to temperatures lower than 100ÂC for extended periods of time, chilled quickly and stored under refrigeration. The aim of this study was to evaluate the quality and shelf life of carrots ( Daucus carot L.) diced submitted to sous vide technology, produced on an industrial scale. The samples were subje cted to physical and chemical analysis and chemical, microbiological and with three replications, with five repetitions of the products, and soon after processing by 2, 4, 6 and 8 weeks of storage (3ÂC). Sensory analysis was carried out on days 0 and 4 weeks, with a repeat. The results indicated a significant difference of 5% (p &#8804;0.05) in carbohydrate, protein, ash, titratable acidity and chromaticity between the carrot fresh carrot and processed by sous vide technology at time 0. In times of 2, 4, 6 and 8 weeks of storage at 3ÂC difference was significant (p &#8804; 0.05) only for protein and total acidity. In sensory analysis, no significant difference (p &#8804; 0.05) in any of the attributes studied. It was also observed that the technology sous vide was effective in eliminating vegetative cells of micro-organisms pathogenic and spoilage, yet not been able to eliminate spores. The carrot processed by sous vide technology retains its nutritional characteristics, sensory, chemical and microbiologically stable for up to eight weeks of storage at 3ÂC. / A cenoura à uma olerÃcola rica em carotenÃides, prÃ-vitamina A, minerais e carboidratos, constituindo um alimento com alto valor nutritivo. O Brasil està entre os cinco maiores produtores e consumidores de cenoura (Daucus carot L.) do mundo, concentrando sua produÃÃo na regiÃo sudeste. Na busca de produtos mais atrativos, prÃticos, nutritivos e saudÃveis pelo consumidor, a tecnologia sous vide surge como uma alternativa tecnolÃgica para a indÃstria no fornecimento de pratos prontos para consumo. O sous vide consiste em cozinhar alimentos acondicionados em embalagens plÃsticas seladas à vÃcuo, submetidos a temperaturas inferiores à 100ÂC por longos perÃodos de tempo, resfriados rapidamente e armazenados sob refrigeraÃÃo. O objetivo desse trabalho foi avaliar a qualidade e a vida de prateleira de cenouras (Daucus carot L.) cortadas em cubos submetida a tecnologia sous vide, produzida em escala industrial. As amostras foram submetidas as anÃlises fÃsico-quÃmicas e quÃmicas, com trÃs repetiÃÃes e microbiolÃgicas, com cinco repetiÃÃes, dos produtos, logo apÃs o tecnologia e por 2, 4, 6 e 8 semanas de armazenamento refrigerado (3ÂC). A anÃlise sensorial foi realizada nos tempos de 0 e 4 semanas, com uma repetiÃÃo. Os resultados indicaram que houve diferenÃa significativa de 5% (p&#8804;0,05) nos carboidratos, proteÃnas, cinzas, acidez total titulÃvel e na cromaticidade entre a cenoura in natura e a cenoura processada por tecnologia sous vide no tempo 0. Nos tempos de 2, 4, 6 e 8 semanas de armazenamento a 3ÂC houve diferenÃa significativa (p&#8804;0,05) apenas nas proteÃnas e acidez total titulÃvel. Na anÃlise sensorial, nÃo houve diferenÃa significativa (p&#8804;0,05) em nenhum dos atributos estudado. Observou-se tambÃm que a tecnologia sous vide foi eficiente na eliminaÃÃo de cÃlulas vegetativas de micro-organismos deteriorantes e patogÃnicos, porÃm nÃo foi capaz de eliminar esporos. A cenoura processada por tecnologia sous vide conservou suas caracterÃsticas nutricionais, sensoriais, quÃmicas e manteve-se estÃvel microbiologicamente atà oito semanas de armazenamento à 3ÂC.

Orientador: Vivaldo Silveira Júnior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-21T09:55:48Z (GMT). No. of bitstreams: 1 Lage_BrunadeCarvalhoFonseca_M.pdf: 7834171 bytes, checksum: 9781ad0b393f78deff771c5484867e54 (MD5) Previous issue date: 2012 / Resumo: Os consumidores têm se mostrado cada vez mais exigentes em relação aos alimentos, na busca de produtos de fácil preparo, e que, também, reúnam qualidades sensoriais e nutricionais. A técnica sous vide consiste em pasteurizar produtos alimentícios embalados a vácuo, de modo que o tratamento térmico mais brando minimize a destruição de nutrientes sensíveis ao calor e a embalagem hermética previna perdas de compostos voláteis responsáveis pelo sabor. O rápido resfriamento após o tratamento térmico e a estocagem sob refrigeração aumentam a vida útil do produto. O pescado é, em geral, um alimento muito perecível, quando comparado com outros alimentos in natura, portanto, as indústrias podem ter uma expansão de mercado ao ter um processamento que consiga manter a qualidade desses produtos por mais tempo. Neste contexto, este trabalho teve como objetivo avaliar as condições de tempo e temperatura do tratamento térmico no processo sous vide de salmão (Salmo salar), bem como acompanhar algumas características do produto durante a sua vida útil. Para isso, foi montado um equipamento termocirculador e ensaiadas porções de 150 g de salmão, as quais foram submetidas a um tratamento térmico de acordo com um planejamento experimental. Os resultados mostraram que os produtos processados com temperaturas mais altas apresentaram textura mais firme e os parâmetros de cor L* aumentou e C* diminuiu, tornando mais clara a coloração do peixe. Porém, não foram identificadas mudanças nessas características ao longo do tempo de estocagem. Os valores de pH não mostraram variação e as amostras apresentaram baixo índice de oxidação lipídica. Conforme o resultado das análises microbiológicas verificou-se que os tratamentos com temperaturas iguais ou inferiores a 50°C não foram suficientes para garantir a segurança do produto por 21 dias de armazenagem. Propôs-se uma correlação de tempo/temperatura (degree-time) com o período de estocagem para estimativas em outras condições de processo / Abstract: Nowadays, consumers are more and more demanding concerning food, seeking to easy cooking food, which also should have sensorial and nutritional qualities. The sous vide technique entails in to pasteurize vacuum-packed food so that, a mild thermal treatment will avoid the destruction of nutrients that are sensitive to heat, and also, the hermetic packing should prevent loss of the volatile substances responsible for the taste. The fast cooling after thermal treatment and the refrigerated storage will increase the shelf life of the product. Fish product is in general, very perishable, compared to other foods in natura, therefore, industries can have their markets improved by having a processing that keep the qualities of these products even longer. In this context, this work aims to evaluate thermal treatment conditions in time/temperature of the salmon (Salmo salar) in the sous vide process, as well to follow some characteristics from the product during its shelf life. For that, a bath tank was assembled and portions of 150 g of salmon, which were submitted to a thermal treatment, according to an experimental design. The results showed that, the products that were processed in higher temperatures, presented firmer texture and the color parameters L* increased and the C* decreased, making the color of the fish lighter. However, changes haven?t been identified in those characteristics during storage. The pH values haven?t shown variation and, the samples have shown lower oxidation levels. According the result of microbiological analysis, it was noted that treatment with temperatures equal or under 50º C don?t assure the safety of the product for 21 days of storage. A degree-time correlation with shelf life was suggested for further calculations in different process conditions / Mestrado / Engenharia de Alimentos / Mestra em Engenharia de Alimentos

L’émission électronique par effet de champ est un domaine qui concerne de nombreuses applications techniques. Dans ce travail, nous avons réalisé une étude essentiellement expérimentale des différents paramètres susceptibles d’avoir une influence sur l’émission électronique. En première partie, nous exposons les résultats obtenus pour un champ électrique homogène correspondant aux faibles intensités de courant. Le rôle de la distance inter-électrodes à champ constant et l’influence de la rugosité de surface sur l’émission électronique ont été étudiés. Nous discutons la méthode classique de Fowler-Nordheim utilisée pour le dépouillement des mesures en y portant un regard critique. Un modèle simple visant à prendre en compte l’échauffement des sites émetteurs est proposé. La seconde partie concerne l’effet de l’injection de gaz sur l’émission électronique, effet qui se traduit par une diminution du courant émis quand on augmente la pression de 10⁻⁶ Pa à 10⁻² Pa à champ macroscopique constant. Nous exposons des résultats montrant un effet de seuil concernant l’apparition de l’effet du gaz sur l’émission électronique. Nous présentons également des résultats pour différents matériaux de cathode et pour différents gaz (He, H₂, N₂, Ar). Une réversibilité de cet effet est montrée après le pompage pour redescendre à 10⁻⁵ Pa. La décroissance de courant par effet de gaz est interprétée par la diminution de la valeur du facteur d’accroissement local du champ électrique (β) au niveau des émetteurs à cause du bombardement de ces sites par les ions créés à leur proximité. Un calcul du flux d’ions bombardant un site émissif a permis d’estimer le temps nécessaire pour modifier un émetteur de façon cohérente avec les observations expérimentales. La théorie de la migration des atomes en surface de l’électrode en présence d’un champ électrique est proposée pour expliquer la réversibilité de l’effet de gaz observée qui est, selon cette théorie, liée à l’augmentation de la valeur de β au niveau des émetteurs. / Field electronic emission is a domain which concerns numerous different technical applications. In this work, we have taken an essentially experimental approach to study various parameters having influence on field emission. In the first part of the thesis, we have described the results obtained with a homogeneous electric field with relatively weak field emission. The role of the inter-electrode distance at constants field as well as that of the cathode surface roughness on field emission are studied. The classical method of Fowler-Norheim was then used for the analysis of the measurements. A simple model aiming to take into account the effect of the heating of the emission sites is then proposed. The second part of the theses concerns the effect of the injection of gas on the field emission; this effect being to significantly reduce emission intensity when the gas pressure is raised from 10⁻⁶ to 10⁻² Pa at constant field. A threshold value of emission intensity is shown to be necessary for the observation of this gas effect. The effect of different gas types (He, H₂, N₂, Ar) and cathode materials are also described. The gas effect is shown to be reversible upon lowering of the gas pressure to 10⁻⁵ Pa. The reduction in current is interpreted by a lowering of the field enhancement factor (β) of emission sites by ionic bombardment by ions created locally (within distances on the order of microns) near the cathode surface. A calculation of the flux of bombarding ions is used to estimate the time necessary to modify an emission site in a way corresponding to the observations. The phenomenon of surface migration in the presence of intense electric field is then proposed to explain the reversibility of the gas effect, increasing the local field enhancement factor.