Thèses sur le sujet « Responsive extrusion »

L'objectif de ce projet est de développer des matériaux polymères par extrusion réactive avec des fonctionnalités modulaires en mettant en œuvre une chimie durable basée sur l'utilisation du dioxyde de carbone comme source de carbone.Le cœur de l'étude est d'introduire des fonctions carbonates cycliques à partir du CO2, via des réactions de carbonatation, sur des polymères industriels pour modifier leurs caractéristiques physico-chimiques telles que leur polarité, leur cristallinité, et leur réactivité sans limiter leur recyclabilité. Le défi du projet est d'appliquer de telles modifications chimiques sur les polyoléfines dans une extrudeuse en une seule étape en traitant le système réactif sous haute pression de dioxyde de carbone.Au cours de cette thèse, trois axes de recherche ont pu être explorés. Le premier axe est la carbonatation de polymères industriels contenant des groupes pendants époxydes en utilisant le CO2 comme réactif et des sels d’ammonium comme catalyseurs organiques. La transposition de cette modification en procédé batch vers un procédé d’extrusion réactive a particulièrement été étudiée. Le deuxième axe est la carbonatation oxydante de polyoléfines insaturées en deux étapes en réacteur batch en utilisant des péracides et le CO2 comme réactifs, et des sels d’ammonium comme catalyseurs organiques. Enfin, le troisième axe est la valorisation de ces polymères carbonatés comme intermédiaires pour la synthèse de polyuréthanes sans isocyanate et comme agents compatibilisants pour des mélanges polyéthylène/polycarbonate
The aim of this project is to develop polymer materials harnessing reactive extrusion with modular functionalities by implementing sustainable chemistry based on the use of carbon dioxide as a carbon source.The core of the study is to introduce cyclic carbonate functions from CO2, via carbonatation reactions, on industrial polymers to modify their physico-chemical characteristics such as polarity, crystallinity, and reactivity without limiting their recyclability. The project's challenge is to apply such chemical modifications to polyolefins in a single-step reactive extrusion process by treating the reactive system under high carbon dioxide pressure.During this thesis, three axes of research were explored. The first is the carbonatation of industrial polymers containing epoxy pendant groups using CO2 as reagent and ammonium salts as organocatalysts. The transposition of this modification from a batch process to reactive extrusion was particularly studied. The second axe is the oxidative carbonatation of unsaturated polyolefins in two steps in a batch reactor using peracids and CO2 as reagents, and ammonium salts as organocatalysts. Finally, the last axis is the valorization of these carbonated polymers as intermediates for the synthesis of isocyanate-free polyurethanes and as compatibilizing agents for polyethylene/polycarbonate blends

Orientador: Caroline Joy Steel
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: É cada vez maior o número de pessoas que procura uma alimentação mais saudável, com alimentos frescos, de boa qualidade biológica e livre de defensivos agrícolas, como são os produtos orgânicos. Percebe-se também que nas dietas contemporâneas em geral existe um "déficit nutricional" de fibras. Este fato tem motivado as autoridades de saúde de diversos países a estimular um maior consumo de fibras por parte da população adulta, seja estimulando o consumo de alimentos como frutas, verduras, leguminosas, raízes, tubérculos e cereais integrais, ou através de produtos comerciais de consumo habitual que tenham sido enriquecidos com fibras. Já existem no mercado ou têm sido estudadas algumas fontes alternativas de fibras, como as fibras de beterraba, de caule de trigo, de laranja, de maracujá e a quitosana. Neste trabalho, optou-se por aproveitar os resíduos da extração de polpa de maracujá como fonte alternativa de fibras. Na extração de polpas e sucos, os resíduos resultantes do processo são normalmente utilizados em ração animal ou como adubo. O objetivo deste trabalho foi estudar o efeito de parâmetros da extrusão termoplástica (umidade da matéria-prima e temperatura de processo) e da adição de fibra sobre propriedades físicas, propriedades físico-químicas e propriedades nutricionais de produtos extrusados, no desenvolvimento de cereal matinal orgânico à base de farinha de milho e farelo de maracujá. A matéria-prima foi caracterizada quanto a sua composição centesimal; teores de fibra alimentar total, solúvel e insolúvel; índices de solubilidade em água (ISA), de absorção de água (IAA), de solubilidade em leite (ISL), de absorção de leite (IAL), de absorção de óleo (IAO), índice glicêmico (IG) e teor de compostos cianogênicos. Após a caracterização da matéria-prima, foi utilizado o processo de extrusão termoplástica para produzir uma base para cereal matinal, otimizando-se a formulação e os parâmetros de extrusão através da Metodologia de Superfície de Resposta, visando a obtenção de um produto com "alto teor de fibras" e propriedades tecnológicas adequadas. Os produtos extrusados foram caracterizados quanto a propriedades físicas, como índice de expansão (IE), cor, dureza e manutenção da textura em leite; propriedades físico-químicas, como ISA, IAA, ISL, IAL e IAO; e propriedades nutricionais, como IG e teor de compostos cianogênicos. Foi observado que o farelo de maracujá utilizado continha alto teor de fibra alimentar total (64,11%), apresentando teores significativos de fibra insolúvel (50,16%) e fibra solúvel (13,95%), ao contrário da farinha de milho que apresentou baixo teor de fibra alimentar total (3,68%), sendo 3,37% fibra insolúvel e 0,31% fibra solúvel. Os valores encontrados na determinação do ISA da farinha de milho e do farelo de maracujá foram 7,14 e 31,66%, respectivamente. O valor do IAA encontrado para a farinha de milho foi de 3,33 g de água/g material seco e para o farelo de maracujá foi de 14,38 g de água/g material seco. Os valores encontrados para o ISL da farinha de milho e do farelo de maracujá foram 5,23 e 14,53%, respectivamente. Os valores do ISL foram menores quando comparados com os valores do ISA. Os valores do IAL encontrados para a farinha de milho e para o farelo de maracujá foram de 3,26 e 12,50 g de leite/g material seco, maiores que os valores de IAA, possivelmente devido à formação de géis de pectina. Os índices de absorção de óleo da farinha de milho e do farelo de maracujá foram de 3,63 e 4,74 g de óleo/g de material seco, respectivamente. Os índices glicêmicos da farinha de milho e do farelo de maracujá foram de 48,03 e 45,00%, respectivamente. O farelo de maracujá apresentou um teor de compostos cianogênicos totais de 748,3 mg/kg. As superfícies de resposta demonstraram que a valores baixos das variáveis estudadas, foi obtida a maior expansão. Já, sobre a dureza dos produtos extrusados, as superfícies demonstraram que o efeito mais importante foi a umidade e a interação dela com a temperatura. Ao aumentar a umidade, a dureza dos produtos extrusados aumentou significativamente. No entanto, foi observado que a temperatura de processo foi o parâmetro que mais influenciou negativamente a textura do produto após 5 minutos de imersão em leite. Em relação à cor dos extrusados, altos níveis de farelo de maracujá diminuíram os valores de L* e hab, produzindo extrusados mais escuros e menos amarelos, ao contrário do efeito da temperatura, onde altas temperaturas aumentaram o valor de L* e o hab, produzindo extrusados mais claros e mais amarelos. Nos produtos extrusados, os maiores valores de ISA foram encontrados para os maiores teores de farelo de maracujá, enquanto que os maiores valores para o IAO foram obtidos com baixos teores de farelo. Aparentemente, não houve efeito das variáveis estudadas sobre o IG dos produtos extrusados. O teor dos compostos cianogênicos foi maior nos produtos com maiores teores de farelo de maracujá, como esperado. Além disso, parace haver um efeito da umidade da matéria-prima na redução dos compostos cianogênicos durante o processo de extrusão. O extrusado considerado como produto ótimo neste trabalho apresentou propriedades adequadas com respeito a IE e dureza. Também apresentou uma porcentagem de fibra alimentar alta (11%), bem superior à exigida pela Legislação Brasileira (6 g/100 g de produto) para ser denominado cereal matinal "com alto teor de fibras"
Abstract: The number of people searching healthier eating habits, including fresh foods of good biological quality and free of pesticides, such as organic products, is increasing. It is also observed that in contemporary diets in general, there is a â?¿nutritional deficitâ?? of fibers. This fact has motivated health authorities of several countries to stimulate a greater ingestion of fibers by the adult population, either by stimulating the consumption of fruits, vegetables, legumes, tubers and wholegrain cereals, or through the enrichment of commonly consumed commercial products. There are already a few alternative fiber sources on the market or under study, such as beetroot, wheat stalk, orange, passion fruit fibers and chitosan. In this work, we opted to use the residues from the extraction of passion fruit pulp as an alternative fiber source. In the extraction of pulps and juices, the residues are usually used as animal feed or fertilizers. The objective of this work was to study the effect of thermoplastic extrusion parameters (raw material moisture content and process temperature) and fiber addition on physical, physical-chemical and nutritional properties of extruded products, as a step in the development of an organic breakfast cereal based on corn flour and passion fruit fiber. The raw material was characterized as to its proximate composition; total, soluble and insoluble fiber contents; water solubility index (WSI), water absorption index (WAI), milk solubility index (MSI), milk absorption index (MAI), oil absorption index (OAI); glycemic index (GI) and cyanogenic compounds. After characterization of the raw material, the thermoplastic extrusion process was used to produce a base for breakfast cereals, optimizing the formulation and process parameters through the Response Surface Methodology, with the aim of obtaining a â?¿high fiber contentâ?? product with adequate technological properties. The extruded products were characterized with respect to physical properties, such as expansion index (EI), color, hardness and maintenance of texture in milk; physicalchemical properties, such as WSI, WAI, MSI, MAI and OAI; and nutritional properties, such as GI and cyanogenic compounds. It was observed that the passion fruit fiber used had a high total fiber content (64.11%), presenting significant contents of insoluble (50.16%) and soluble (13.95%) fibers, different to the corn flour used that presented a low total fiber content (3.68%), of which 3.37% were insoluble fibers and 0.31% soluble fibers. The values found for the WSI of the corn flour and passion fruit fiber were 7.14 and 31.66%, respectively. The values found for the WAI of the corn flour and of the passionfruit fiber were 3.33 and 14.38 g water/g dry material, respectively. The values found for the MSI of the corn flour and passion fruit fiber were 5.23 and 14.53%, respectively. The MSI values were lower than the WSI values. The values found for the MAI of the corn flour and passion fruit fiber were 3.26 and 12.50 g milk/g dry material, higher than those of WAI, possibly due to the formation of pectin gels. The oil absorption indices of the corn flour and passion fruit fiber were 3.63 and 4.74 g oil/g dry material, respectively. The glycemic indices of the corn flour and passion fruit fiber were 48.03 and 45.00%, respectively. The content of cyanogenic compounds in passion fruit fiber were 748,3 mg/kg. The response surfaces demonstrated that at low values of the variables studied, greatest expansion was obtained. For the hardness of the extruded products, the surfaces demonstrated that the most important effect was moisture and its interaction with temperature. Increasing moisture, the hardness of the extruded products increased significantly. However, it was observed that process temperature was the parameter that had the greatest negative effect on the texture of the products after 5 minutes in milk. With respect to color of the extrudates, high levels of passion fruit fiber reduced L* and hab values, producing darker and less yellow extrudates, different to the effect of temperature, where high temperatures increased L* and hab values, producing lighter and more yellow extrudates. In the extruded products, the highest values for WSI were found with the highest passion fruit fiber contents, while the highest values for OAI were obtained with low fiber contents. Apparently, there was no effect of the variables studied on the GI of the extruded products. The content of cyanogenic compounds was higher in the products with greater percentages of passion fruit fiber, as expected. Apart from this, there seems to be an effect of raw material moisture content in the reduction of cyanogenic compounds during the extrusion process. The extrudate considered optimum in this work presented adequate properties with respect to EI and hardness. It also presented a high percentage of dietary fiber (11%), higher than that required by the Brazilian Legislation (6 g/100 g product) to be labeled as a â?¿high fiber contentâ?? breakfast cereal
Mestrado
Mestre em Tecnologia de Alimentos

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Pearl millet is a rich nutritionally cereal, being a major source of protein countries of the semiarid region of the African continent. The pearl millet crops are in expansion on Brazilian Savanna due the plant characteristics that are compatible to the climate and soil of the region. However, in Brazil, the grains of millet are not widely used in food, it was noted with advantageous insertion of this cereal in the diet of the population as this has major advantages over other commonly used cereals as the lowest price, the more quantity and better quality of fiber lipid and protein. The thermoplastic extrusion was used for the preparation of products with the millet that was mixed with corn grits because it presents favorable characteristics for processing used. This study was conducted in order to develop and evaluate the nutritional quality, technological and sensory snacks, pre-gelatinized flour (FPG) and pasta-based mixture of millet [Pennisetum glaucum (L.) R. Br] and gritz of corn (Zea mays L.). For extruding the mixture of grains of millet and corn gritz was used rotational central composite design for the best moisture conditions of the raw material and temperature of the extruder zone 3. The snacks were optimized according to the expandability and pregelatinized flour according to the absorption capacity and water solubility. After optimization of flour, which showed better gelatinization was applied in the preparation of pasta. This was prepared using the mixture design with ternary composition (extruded flour, corn flour and millet raw) to find what proportion of ingredients that got the best features of cooking pasta. Snacks with 11% moisture content of the raw material and 90 ° C temperature were those with greater expansion and were the most desirable second test of desirability. When they were being flavored sensory acceptance and its nutritional composition were classified as high fiber content. The pre-gelatinized flour with highest absorption capacity and water solubility was the one with the same extrusion conditions optimized snack. The proportion of ingredients of the mass had the best cooking conditions was 10% pre-gelatinized flour, 25% corn and 65% of pearl millet flour. The pasta was accepted for flavor, texture and appearance of the panelists. However, it was possible to extrude grains of millet and corn gritz and also the development of products with good nutritional and sensory characteristics.
O milheto é um cereal rico nutricionalmente, sendo uma das principais fontes proteicas em países da região semiárida do continente Africano. No Brasil, mais especificamente no Cerrado, o cultivo deste cereal apresenta-se em expansão devida as características da planta que são compatíveis ao clima e solo da região. No entanto, no Brasil, os grãos de milheto não são muito utilizados na alimentação humana, com isso notou-se vantajoso a inserção deste cereal na alimentação da população já que este apresenta grandes vantagens em relação a outros cereais comumente utilizados, como o preço mais baixo, a maior quantidade de fibras e a melhor qualidade proteica e lipídica. A extrusão termoplástica, uma técnica bastante versátil, foi utilizada para a elaboração de produtos com o milheto que foi misturado ao gritz de milho por este apresentar características favoráveis ao processamento utilizado. Este estudo foi realizado com o objetivo de desenvolver e avaliar a qualidade nutricional, tecnológica e sensorial de snacks, farinha prégelatinizada e massa alimentícia à base de mistura de milheto [Pennisetum glaucum (L.) R. Br.] e gritz de milho (Zea mays). Para a extrusão da mistura de grãos de milheto e gritz de milho foi utilizado o delineamento composto central rotacional para obter as melhores condições de umidade da matériaprima e temperatura da 3ª zona do extrusor. Os snacks foram otimizados conforme a capacidade de expansão e a farinha pré-gelatinizada de acordo com a capacidade de absorção e solubilidade em água, ou seja, gelatinizada. A farinha pré-gelatinizada otimizada foi aplicada na elaboração de massa alimentícia. Esta foi elaborada utilizando o delineamento de misturas com composição ternária (farinha extrusada, fubá de milho e farinha de milheto crua) para encontrar qual a proporção de ingredientes que obtivesse as melhores características de cozimento da massa. Os snacks e a massa alimentícia foram analisados microbiologicamente para a realização da análise sensorial. Os snacks com 11% de umidade da matéria-prima e 90 °C de temperatura foram os que apresentaram maior expansão e foram os mais desejáveis segundo teste de desejabilidade. Ao serem aromatizados eles foram aceitos sensorialmente e em sua composição nutricional foram classificados como alto teor de fibras. A farinha pré-gelatinizada que obteve maior capacidade de absorção e solubilidade em água também foi o experimento com 11% de umidade e 90 °C de temperatura. A proporção de ingredientes da massa que teve as melhores condições de cozimento foi a de 10% farinha pré-gelatinizada, 25% de fubá de milho e 65% de farinha de milheto. A massa alimentícia foi aceita em relação ao sabor, textura e aparência entre os provadores. Contudo, foi possível a extrusão de grãos inteiros de milheto e gritz de milho e ainda a elaboração de produtos com boas características nutricionais, tecnológicas, microbiológicas e sensoriais segundo atributos sabor, aparência e textura.

Orientador: Caroline Joy Steel
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Mestrado
Mestre em Tecnologia de Alimentos

O processo de cozimento por extrusão é uma técnica de grande importância para a indústria de alimentos, empregada na produção de snacks, cereais matinais, proteínas texturizadas, etc. Os snacks ou salgadinhos com base de milho são designados como alimentos desprovidos de valor nutricional, mas constituem-se hábito de consumo da população, sendo assim, melhorar a qualidade de tais produtos é uma importante medida de Saúde Pública. O presente trabalho teve por objetivo desenvolver um processo para obter um snack de milho com adição de linhaça e maior valor nutricional que tenha potencial para intervenções nutricionais em grupo populacional específico ou para consumo geral. A partir de ensaios prévios foram delineados dois planejamentos compostos centrais (D1 e D2), com 3 variáveis independentes: umidade (U), temperatura do equipamento (T) e adição de linhaça (L). As variáveis-resposta foram razão de expansão (RE) e força para cisalhamento (FC) por estarem diretamente correlacionadas com a aceitabilidade do produto. A regressão para o modelo quadrático do D1 apresentou R2 (%) de 89 (RE) e 84,4 (FC), mas houve falta de ajuste do modelo (p<0,05). Já para o D2 o R2 foi 84 (RE) e 70 (FC), o modelo não apresentou falta de ajuste e a regressão foi significativa (p<0,05) somente para RE. Foram significativos os efeitos lineares U e T, quadrático U e interação UT, independendo de L. Calculando-se as derivadas do modelo preditivo foi encontrado ponto ótimo que reproduziu a expansão máxima. O snack ótimo (30% L) apresentou composição (base seca): 14,7% proteína, 0,2% lipídeos, 1,7% cinzas, 4,9% fibras solúveis e 10,3% fibras insolúveis. Na análise sensorial o atributo cor foi rejeitado e sabor, textura e aparência geral foram aceitos. Comparado aos snacks de milho convencionais, que contém menos de 2% de fibras, a adição de linhaça permitiu o uso do atributo “alto teor de fibras”, segundo a legislação brasileira, além da maior quantidade protéica obtida. O presente trabalho está submetido à patente intitulada: Farinha para fabricação de gêneros alimentícios, solução aromatizante livre de gordura vegetal hidrogenada para fabricação de gêneros alimentícios, biscoito tipo "snack" light e de elevado valor nutritivo, e processo para a fabricação do mesmo. 2005. Patente: Privilégio de Inovação no 0502694-6.
Extrusion cooking is a very important process for the food industry, used to manufacture a series of products as expanded snack foods, breakfast cereals, texturized proteins, etc. Corn snacks are nick-named as “junked foods” or are being considered foods with calories and no nutrients. Nevertheless they are largely consumed by the population, and this consumption has grown considerably in the past years, because of that, to improve nutritional value of those products will have a significative impact in population health. The aim of this work was to develop a process to obtain a corn based snack added of flaxseed with high nutritive quality that could be useful in nutritional programs. After initial experiments, 2 central composite designs (D1 and D2) were modeled, with 3 independent variables: moisture, temperature and flaxseed addition. The dependent (response) variables were: expansion ratio (ER) and shear strength (SS) because they are highly correlated with acceptability. The regression analysis for the quadratic model showed: D1: R2 = 89% (ER) and 84% (SS), but the model showed lack of fit; D2: R2 = 84% (ER) and 70% (SS), the model didn’t show lack of fit and the regression was statistically significant only for ER (p< 0.05). The results indicated that linear effects of both moisture and temperature, second order effect of temperature and interaction between moisture and temperature were significant. Flaxseed addition wasn’t significant. The derivatives of ER indicated an optimum point that reproduced maximum expansion. The optimum snack (30% flaxseed) has the composition (d.s.b.): 14.7% protein, 0.2% lipids, 1.7% ash, 4.9% soluble fiber and 10.3% insoluble fiber. The sensorial analysis revealed that color was rejected and flavor, texture and general aspect were accepted. Comparing to the traditional corn snacks that have less than 2% of fiber, the corn based flax snack besides the increment in protein can be named “high content of fiber” according to the Brazilian legislation.

Sorghum is a major drought and high temperature tolerant grain crop currently used mainly as animal feed in Australia. This study investigated high temperature high pressure extrusion cooking for the manufacture of snack-food like products using sorghum. Response surface methodology statistical modelling was successfully used to specify the optimal formulation and processing conditions to manufacture an expanded product with high levels of slowly digestible starch with potential for assisting in healthy blood glucose control.

Parmi les différents procédés d’élaboration de minigranules, le procédé d’extrusion-sphéronisation présente de nombreux avantages, puisqu’il permet notamment d’élaborer des minigranules fortement chargées en principe actif et d’éviter l’emploi de solvants organiques. Ce travail a pour objectif de comparer les performances de plusieurs systèmes d’extrusion à vis, de l’échelle du laboratoire jusqu’à la transposition à l’échelle industrielle. Pour cela, des plans d’expériences ont été construits afin d’identifier les variables critiques et de sélectionner l’extrudeur le plus favorable selon différentes approches spécifiques à cette étude. En effet, le système d’extrusion idéal est défini dans ce travail comme celui donnant les meilleurs résultats en termes de productivité et de caractéristiques des minigranules (« qualité »), entraînant le moins d’impact sur le produit après transposition d’échelle (« transposabilité »), montrant le moins d’influence sur le produit lorsque la formule utilisée change (« robustesse »), et permettant d’ajuster ou d’améliorer la qualité des minigranules lorsque les conditions opératoires varient (« flexibilité »). Quelle que soit l’approche étudiée, les résultats ont permis de mettre en évidence l’influence de paramètres critiques et de leurs interactions sur les différentes réponses et ont montré des différences entre les différents systèmes d’extrusion. L’étude à l’échelle du laboratoire a permis de comparer les extrudeurs radial, dôme et frontal et a mis en évidence l’intérêt des systèmes frontal et dôme en termes de qualité des minigranules, et du système radial en termes de robustesse et de flexibilité du procédé. L’étude à l’échelle industrielle a permis de comparer les extrudeurs radial et frontal, et a permis d’identifier l’extrudeur frontal comme étant le plus favorable en termes de qualité des minigranules, de robustesse, de flexibilité et de transposabilité. Les conclusions observées à l’échelle industrielle sont donc différentes de celles considérées à l’échelle du laboratoire, pour l’étude comparative des différents systèmes. Cela confirme l’importance de tester les systèmes à échelle industrielle avant l’acquisition d’un équipement
Among the various methods of developing minigranules, extrusion-spheronization has many advantages, particularly since it allows to develop minigranules highly charged with active pharmaceutical ingredient and to avoid the use of organic solvents. This work aims to compare the performance of several extrusion screws systems, from the lab to the scale-up at industrial scale. Designs of experiments were built to identify critical variables and compare the extruder in terms of different approaches specific to this study. As a matter of fact, the ideal extrusion system is defined in this work as the one which gives the best results in terms of productivity and pellets characteristics (“quality”), the one which shows less impact on the product after scaling-up (“scalability”), the one which shows the less influence on these same properties when the formula used changes (“robustness”), and the one which allows the possibility to adjust or improve pellets properties with operating variables (“flexibility”). Whatever the approach studied, the results allowed to highlight the influence of critical parameters and their interactions on the different responses and showed differences between the different extrusion systems. The study at lab scale compared radial, dome and axial extruders and underlined the interest of axial and dome systems in terms of pellets quality, and radial system in terms of process robustness and flexibility. The study at industrial scale compared radial and axial systems, and identified the axial system as the most favorable in terms of pellets quality , robustness, flexibility and scalability. The conclusions observed at industrial scale are different from those observed at lab scale for the different systems comparative study. This confirms the importance to test systems at industrial scale before investing in one equipment

Introdução: A polpa farinácea do jatobá-do-cerrado (Hymenaea stigonocarpa Mart.) apresenta alto teor de fibra alimentar, em média 60 g/100 g, que são importantes para a redução do risco e controle de doenças crônicas não transmissíveis (DCNT). A extrusão termoplástica neutraliza aromas intensos, proporciona a formação de amido resistente, aumenta a fibra alimentar solúvel e melhora a textura do produto final. Objetivo: Estudar o efeito das farinhas de jatobá-do-cerrado in natura (FIN) e extrusada (FE) no metabolismo lipídico e parâmetros fermentativos em hamsters, bem como verificar a resposta glicêmica em humanos após a extrusão. Métodos: Processo de extrusão: velocidade de 200 rpm; matriz com 4 mm de diâmetro; taxa de compressão 3:1; alimentação constante de 70 gramas/minuto; temperatura de 150 °C; proporção farinha de jatobá-do-cerrado e amido de milho: 70:30 por cento e umidade a 25 por cento . Foi realizado um experimento animal com hamsters durante 21 dias, em que se analisou alguns parâmetros do metabolismo lipídico e colônico (fermentativos) dos animais, divididos em quatro grupos experimentais, se diferenciando pela dieta. As dietas controle (GC), in natura (GFI) e extrusada (GFE) eram hipercolesterolemizantes (13,5 por cento de gordura de coco e 0,1 por cento de colesterol) e a dieta referência (GR) com óleo de soja como fonte lipídica, não. Todas as dietas apresentavam 15 por cento de fibra alimentar, sendo que as dietas GR e GC tinham como fonte de fibra a celulose, e as dietas GFI e GFE tiveram as próprias fibras como fonte. A resposta glicêmica em humanos foi verificada por meio do ensaio do índice glicêmico e carga glicêmica da FE, com dez voluntários saudáveis que consumiram 25 gramas de carboidratos disponíveis do alimento teste (farinha extrusada) ou do pão branco como alimento controle. Resultados: Não foi observada diferença significativa entre o peso final, ingestão diária média e total, ganho de peso e CEA entre os animais dos quatro grupos. A concentração de triglicerídeos foi menor em 41 por cento e 38 por cento nos animais que receberam as dietas GFI e GFE, em relação aqueles que receberam a dieta GC, assim como também para o colesterol total (55 por cento e 47 por cento ), LDL-c (70 por cento e 53 por cento ) e não-HDL-c (63 por cento e 49 por cento ) séricos, lipídeos totais hepáticos (39 por cento e 45 por cento ) e o peso dos fígados dos animais também foi menor (21 por cento em ambos os grupos). Não houve diferença no colesterol hepático e excretado nas fezes dos animais dos quatro grupos. Os animais do GFE excretaram 57 por cento mais ácidos biliares nas fezes que os animais do GC. Com relação aos parâmetros fermentativos, observou-se maior excreção de fibras (1,24 ± 0,08 e 1,52 ± 0,09 gramas) nos animais dos grupos GR e GC respectivamente, em relação aos do GFI e GFE (0,50 e 0,48 gramas), porém o escore fecal (3,50 ± 0,19 e 3,38 ± 0,18) e o grau de fermentação (54 e 52 por cento ) foi maior nos animais dos grupos GFI e GFE. Houve uma maior produção de AGCC no ceco dos animais dos grupos GFI e GFE (80 e 57,5 µmol/g de ceco respectivamente) e maior diminuição do pH no conteúdo cecal nos animais do grupo GFI (7,49 ± 0,10), em relação ao GC (8,06 ± 0,13). Os ácidos acético e propiônico, estiveram presentes em maior quantidade no ceco dos animais dos grupos GFI (58,5 e 6,1 µmol/g de ceco) e GFE (42,5 e 6,6 µmol/g de ceco) e os animais do GFI produziram mais ácido butírico (15 µmol/g de ceco), em relação aos demais grupos. Quanto à resposta glicêmica da farinha pós extrusão, não houve diferença entre a área de resposta glicêmica da farinha extrusada e do pão branco, o índice glicêmico da farinha extrusada (glicose como controle) foi classificado como moderado, e a carga glicêmica (na porção de 30 gramas), baixa. Conclusão: As FIN e FE favoreceram a redução do colesterol total, LDL-c, não-HDL-c e dos triglicerídeos séricos, além da diminuição do acúmulo de lipídeos hepáticos. Foi observado também aumento expressivo na formação de AGCC e no grau de fermentação. A FE proporcionou um aumento na excreção de ácidos biliares nas fezes e apresentou índice glicêmico moderado e baixa carga glicêmica.
Introduction: The mealy pulp of jatobá-do-cerrado (Hymenaea stigonocarpa Mart.) has high dietary fiber content, on average 60 g/100 g, which is important for reducing risk and control chronic non-communicable diseases (NCDs). The thermoplastic extrusion neutralizes intense flavors, formation of resistant starch, increases soluble dietary fiber and improves the texture of the final product. Objectives: Check the effect of jatobá-do-cerrado flour in natura (IF) and extruded (EF) on lipid metabolism and fermentation parameters in hamsters as well as the glycemic response in humans after extrusion. Methods: Extrusion cooking: speed of 200 rpm; 4 mm die diameter; compression ratio 3:1; constant feed rate 70 g/min; temperature 150 °C; ratio of jatobá-do-cerrado flour to corn starch: 70:30 per cent and 25 per cent moisture. A 21-day biological experiment with hamsters was conducted, in which parameters of the animals lipid metabolism and colonic (fermentation) were analyzed; they were divided into four groups, differing by diet. The control diets (CG), in natura (IFG) and extruded (EFG) were hypercholesterolemic (13.5 per cent coconut fat and 0.1 per cent cholesterol), and the reference diet (RG) with soybean oil as a lipid source was not. All diets had 15 per cent of dietary fiber, being that RG and CG diets had the cellulose fiber source, and IFG and EFG diets had the fibers themselves as a source. The glycemic response in humans was evaluated by the glycemic index and glycemic load test of EF, with ten healthy volunteers who consumed 25 grams of available carbohydrate food test (extruded) or white bread as food control. Results: There was no significant difference between final weight, average total and daily intake, weight gain and FER between animals of the four groups. The values of triglycerides were lower by 41 per cent and 38 per cent in the animals receiving the IFG and EFG diets, for those who received the CG diet, as well as for total cholesterol (55 per cent and 47 per cent ), LDL-c (70 per cent and 53 per cent ) and non-HDL-c levels (63 per cent and 49 per cent ) serum, liver lipids (39 per cent and 45 per cent ) and the animals\' livers weight was lower (21 per cent in both groups). There was no difference in hepatic cholesterol and excreted in feces of animals of the four groups. The animals of the EFG group excrete 57 per cent more bile acids in stool than animals CG. Regarding the fermentation parameters, we observed increased excretion of fibers (1.24 ± 0.08 and 1.52 ± 0.09 g) in animals of RG and CG respectively, in relation to IFG and EFG (0.50 and 0.48 grams), but the fecal score (3.50 ± 0.19 and 3.38 ± 0.18) and the degree of fermentation (54 and 52 per cent ) were higher in animal IFG and EFG groups. There was a greater production of SCFA in the caecum of animals IFG groups and EFG (80 to 57.5 µmol/g caecum respectively) and greater decrease in pH in the cecal contents of IFG animals group (7.49 ± 0.10) compared to the control group (8.06 ± 0.13). The acetic and propionic acids were present in higher amounts in the caecum of animals IFG groups (58.5 and 6.1 µmol/g caecum) and EFG (42.5 and 6.6 µmol/g caecum) and the animals of IFG group produced more butyric acid (15 µmol/g caecum), compared to other groups. Concerning the glycemic response of flour after extrusion, there was no difference between the glycemic response area of extruded flour and white bread, the glycemic index of extruded flour (glucose as a control) was classified as moderate and glycemic load (the portion of 30 grams) low. Conclusion: IF and EF aided in the reduction of total cholesterol, LDL-c, non-HDL-c and triglycerides, as well as decreased the accumulation of liver lipids. A significant increase in the SCFA and degree of fermentation was also observed. The EF increased the excretion of bile acids in stool, and presented moderate glycemic index and low glycemic load.

NiTiHf alloys have attracted considerable attention as potential high temperature Shape Memory Alloy (SMA) but the instability in transformation temperatures and significant irrecoverable strain during thermal cycling under constant stress remains a major concern. The main reason for irrecoverable strain and change in transformation temperatures as a function of thermal cycling can be attributed to dislocation formation due to relatively large volume change during transformation from austenite to martensite. The formation of dislocations decreases the elastic stored energy, and during back transformation a reduced amount of strain is recovered. All these observations can be attributed to relatively soft lattice that cannot accommodate volume change by other means. We have used Equal Channel Angular Extrusion (ECAE), hot rolling and marforming to strengthen the 49.8Ni-42.2Ti-8Hf (in at. %) material and to introduce desired texture to overcome these problems in NiTiHf alloys. ECAE offers the advantage of preserving billet cross-section and the application of various routes, which give us the possibility to introduce various texture components and grain morphologies. ECAE was performed using a die of 90º tool angle and was performed at high temperatures from 500ºC up to 650ºC. All extrusions went well at these temperatures. Minor surface cracks were observed only in the material extruded at 500 °C, possibly due to the non-isothermal nature of the extrusion. It is believed that these surface cracks can be eliminated during isothermal extrusion at this temperature. This result of improved formability of NiTiHf alloy using ECAE is significant because an earlier review of the formability of NiTiHf using 50% rolling reduction concluded that the minimum temperature for rolling NiTi12%Hf alloy without cracks is 700°C. The strain level imposed during one 90° ECAE pass is equivalent to 69% rolling reduction. Subsequent to ECAE processing, a reduction in irrecoverable strain from 0.6% to 0.21% and an increase in transformation strain from 1.25% to 2.18% were observed at a load of 100 MPa as compared to the homogenized material. The present results show that the ECAE process permits the strengthening of the material by work hardening, grain size reduction, homogeneous distribution of fine precipitates, and the introduction of texture in the material. These four factors contribute in the increase of stability of the material. In this thesis I will be discussing the improvement of mechanical behavior and stability of the material achieved after various passes of ECAE.

碩士
國立虎尾科技大學
機械與機電工程研究所
102
The aim of this study was to investigate the difference between three kinds of bone tissue scaffolds on cell viability and mechanical properties by using thermal extrusion three-dimensional printing system to synthesize kinds of materials which are mPEG-PCL-mPEG polymer, Zirconia and Hydroxyapatte. By changing the moving path of thermal extrusion three-dimensional printing system can make the holes form in the side of bone tissue scaffolds and increase porosity on scaffold, holes in the front can be maintained in 450-500μm while holes in the side can be controlled at a height of about 200μm. After synthesized mPEG-PCL-mPEG polymer worked through MTT in-vitro cell culture assays for 1, 3, 5, 7, 9 days, the trend of cell proliferation can be proved. The scaffold for bone tissue that is added Zirconia has no impact on cell growth, and can increase mechanical properties of scaffold through the test of compression and hardness. The trend of cell proliferation can be more obvious after adding Hydroxyapatte to bone tissue scaffold.

碩士
國立高雄海洋科技大學
水產食品科學研究所
102
Orang (Citrus sinensis L. cv.) and calamondin (Citrus microcarpa Bonge) are important agricultural crops in Taiwan. After processing, a great quantity of pomace was produced. Pomace is rich in dietary fiber. It is worthwhile to deeply investigate the development and utilization of the pomace by different processing. The study was to investigate the optimization of extruded pomace derived from orange and calamondin using response surface methodology. Tested extrusion variables were barrel temperature (115C, 125C, 135C), moisture contents (10, 14, 18 g/100 g) and screw speed (230, 290, 350 rpm). Soluble dietary fiber content in each treatment group serves as an evaluable index to obtain optimal conditions. Meanwhile, the effect of extrusion processing on physicochemical properties of extrudates as well as in vitro physiological tests such as glucose absorption, cholesterol micelle solubility capacity and bile acid binding capacity of extrudates were also evaluated. Finally, the use of optimal extrusion conditions would further develop a high-fiber bakery product with nutritional function, and investigate its quality. The results showed that soluble dietary fiber content of extrudates was significantly influenced by above three variables. From calculation of regression equation, it showed that optimal extrusion condition: barrel temperature, moisture content, and screw speed of extruded orange pomace is 131.6C, 16 g/100 g and 304.8 rpm, respectively; while barrel temperature, moisture content, and screw speed of extruded calamondin pomace is 128.5C, 15.6 g/100 g , 298.1 rpm, respectively. The soluble dietary fiber contents of orange and calamondin pomace were 17.3% and 24.6%, respectively before extrusion. Processing conditions increased soluble dietary fiber content up to 29.8% and 40.0%, respectively for orange pomace and calamondin pomace. These pomace processed by single extruder significantly (P < 0.05) change the physicochemical properties such as bulk density, water-retention capacity, swelling property, cation-exchange capacity, water solubility index, dispersibility, emulsification activity, and gelation property in which they had higher properties than those before extrusion. The results of In vitro experiments indicate that orange and calamondin extrudates than the cellulose and non-extruded pomaces could effectively retard glucose absorption. Orange and calamondin pomace after extrusion was found to significantly (P < 0.05) decrease the amount of intact cholesterol-micelle than those without extrusion processing. Increased addition of extruded pomace into bread formulation resulted in decreases of total area and specific volume as well as increases of cell area and hardness. The substitution of extrude pomace into bread formulation at the level of 5% significantly (P < 0.05) influences the bread color, but sensory evaluation has indicated that the bread product are acceptable to the target audience. In conclusion, oranges and calamondin pomace by extrusion processing than those without extrusion, had good physicochemical properties and physiological functions in vitro.

TiNiPd high-temperature shape memory alloys (HTSMAs) have attracted considerable attention as potential solid-state actuators capable of operating at temperatures up to 500 °C, exhibiting excellent corrosion resistance, adequate ductility levels and significant strain recovery under both constrained and unconstrained thermomechanical conditions. During operation, these actuators may be subjected to multiple cycles and from an application point of view, the functional stability, i.e. conservation of original actuator dimensions and transformation temperatures during repeated employment, is of considerable importance. This study addresses the issue of functional stability in a model HTSMA, Ti50.5Ni24.5Pd25, for its use as a compact solid-state actuator. Since the primary reason for functional instability is the creation of lattice defects (dislocations, vacancies, etc.) during repeated transformation cycles, several methods were successfully undertaken to improve the functional stability through inhibiting the generation of these defects. Solid-solution strengthening through Sc microalloying and thermomechanical treatments via severe plastic deformation were the two approaches used to strengthen the HTSMA against defect generation. Thermal cycling the HTSMA under stress was the third method to voluntarily introduce defects into the microstructure such that further defect generation during application would be impeded. Overall, severe plastic deformation was found to be more efficient than other strengthening methods in improving the functional stability of TiNiPd HTSMA, yet it brought about disadvantages such as reduction in transformation strain and transformation temperatures. While functional instability is due to the creation of lattice defects, the generation of these defects is mainly controlled by the crystallographic incompatibility between martensitically transforming phases and the strength levels for plastic deformation. It was shown that TiNiPd HTSMAs, which exhibited martensitic transformation from a cubic (B2) to orthorhombic (B19) symmetry, illustrated better compatibility and thus better functional stability levels compared to TiNi SMAs, which had a B2 to monoclinic (B19’) transition. Although crystallographic incompatibility seems to be the governing factor for the functional stability of the TiNiPd HTSMA, the strength differential between the onset of plastic deformation and local constraint due to the martensitic transformation was also found to be an influential factor determining the overall stable behavior. Functional stability was also investigated for the two-way shape memory effect (TWSME) in TiNiPd HTSMAs. Better strength and compatibility levels compared to TiNi SMAs were also reflected in the TWSME characteristics in the form of enhanced stability under stress-free thermal cycling. The stability during constrained thermal cycling was not as good and TWSME degraded rapidly while doing work against an opposing stress. Nevertheless, work output levels were much higher as compared to those obtained from conventional TiNi and Cu-based SMAs.

Hexagonal closed packed (hcp) materials, in contrast to cubic materials, possess several processing challenges due to their anisotropic structural response, the wide variety of deformation textures they exhibit, and limited ductility at room temperature. The aim of this work is to investigate, both experimentally and theoretically, the effect os severe plastic deformation, ultrafine grain sizes, crystallographic textures and number of phases on the flow stress anisotropy and tension compression asymmetry, and the mechanisms responsible for these phenomena in two hcp materials: AZ31B Mg alloy consisting of one phase and Zn-8wt.% Al that has an hcp matrix with a secondary facecentered cubic (fcc) phase. Mg and its alloys have high specific strength that can potentially meet the high demand for light weight structural materials and low fuelconsumption in transportation. Zn-Al alloys, on the other hand, can be potential substitutes for several ferrous and non-ferrous materials because of their good mechanical and tribological properties. Both alloys have been successfully processed using equal channel angular extrusion (ECAE) following different processing routes in order to produce samples with a wide variety of microstructures and crystallographic textures for revealing the relationship between microstructural parameters, crystallographic texture and resulting flow stress anisotropy at room temperature. For AZ31B Mg alloy, the texture evolution during ECAE following conventional and hybrid ECAE routes was successfully predicted using visco-plastic self-consistent (VPSC) crystal plasticity model. The flow stress anisotropy and tension-compression (T/C) asymmetry of the as received and processed samples at room temperature were measured and predicted using the same VPSC model coupled with a dislocation-based hardening scheme. The governing mechanisms behind these phenomena are revealed as functions of grains size and crystallographic texture. It was found that the variation in flow stress anisotropy and T/C asymmetry among samples can be explained based on the texture that is generated after each processing path. Therefore, it is possible to control the flow anisotropy and T/C asymmetry in this alloy and similar Mg alloys by controlling the processing route and number of passes, and the selection of processing conditions can be optimized using VPSC simulations. In Zn-8wt.% Al alloy, the hard phase size, morphology, and distribution were found to control the anisotropy in the flow strength and elongation to failure of the ECAE processed samples.