Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliography.

Thesis (M.Phil.) - University of Queensland, 2005. / Includes bibliography.

Universiẗat, Diss., 2000--Stuttgart.

Master of Science / Department of Grain Science and Industry / Sajid Alavi / Sorghum, millets and teff are important staple crops worldwide, especially in semi-arid regions of Africa and India because of their drought tolerance. However, lack of research and other limitations have restricted their usage in food products. This study is focused on extrusion processing of low and high tannin sorghum varieties, millet and teff for high and low moisture applications, and to investigate process characteristics such as residence time distribution and specific mechanical energy, physico-chemical properties of resultant food products (such as pre-cooked pasta and expanded snacks) and their resistance starch content. Results from preliminary lab scale extrusion, including optimization of starch type and level for pre-cooked pasta and in-barrel moisture for expanded snacks, were used to design pilot-scale studies on a twin-screw extruder. In the first pilot-scale experiment, decorticated white sorghum blends prepared with addition of mono-glycerides (0.5%, 1% and1.5%) and salt (1%) were processed at three different in-barrel moisture contents 40%, 44% and 48% (wet basis) for processing of precooked pasta. The optimum formulation containing 1% mono-glycerides and process conditions corresponding to 48% in-barrel moisture were also used to develop precooked teff and millet pasta. The non-traditional grain based pastas were investigated for cooking quality, thermal characteristics using differential scanning calorimeter, pasting properties using rapid visco analyzer and texture profile analysis. In general, increasing in-barrel moisture led to reduction in solid losses (ranging from 4.0-8.2% for all treatments), indicating improvement in cooking quality. On the other hand, increase in mono-glycerides concertation led to higher cooking losses, and also affected pasting and textural properties significantly. Sorghum-based precooked pasta was of best quality while millet pasta was poorest in cooking quality, visual and textural attributes. Cooking loss for control pre-cooked pasta produced in this experiment using semolina was 4.5%, and commercial semolina pasta was 3.2%. Residence time distribution in pilot-scale twin screw extruder, during high moisture process conditions used for pre-cooked pasta, was also investigated at three different in-barrel moistures (40%, 44% and 48%) and monoglycerides/ lipid (0.5, 1% and 1.5%) concentrations. Increase in in-barrel moisture significantly decreased mean residence time. For example, mean residence time was 4.47 min at 40% moisture, 3.89 min at 44% and 3.74 min at 48%. On the contrary, residence time significantly increased with lipid level. For example, mean residence time was 3.87 min at 0.5% concentration of mono-glycerides, 4.48 min at 1% and 4.70 min 1.5%. In the second experiment focusing on low moisture applications, pilot-scale twin screw extrusion was used to process decorticated white sorghum and high tannin sumac sorghum for expanded snacks. The addition of sumac bran decreased the specific mechanical energy input (366-578 kJ/kg) and expansion ratio (6.4-7.9), and resulted in higher piece density of extrudates. Use of sumac bran and sumac flour led to increase in resistant starch content, although it was less than 1% for all treatments. Therefore, extrusion with ingredients having high tannin content does not provide value, despite tannins being associated with resistant starch at least in raw materials.

Master of Science / Department of Grain Science and Industry / Sajid Alavi / This study relates raw material particulate rheology to the granular flow in a single screw food extruder. Raw materials based on corn (i.e. meal, flour, and starch), wheat (i.e. farina, flour and starch), and sucrose (i.e. granulated, superfine, and powdered) were used as model particulate systems for the study. Various particulate-scale characteristics and flow parameters of these nine materials were determined using a powder rheometer. Properties such as basic flow energy, cohesion, flow function, and effective angle of internal friction were good indicators of flowability in an extruder. Corn meal exhibited lower energy requirements and a higher propensity for flow than corn flour (6.7mJ/g versus 10.7mJ/g, and “free-flowing” versus “cohesive,” according to Flow Function classifications), with wheat farina showing similar results when compared to wheat flour (5.8mJ/g versus 7.9mJ/g, and “highly free-flowing” versus “cohesive”), although both wheat systems showed lower energy requirements than their comparable corn systems. Sugar, being of a different base material and particle shape, behaved differently than these starch-based materials—flow energy decreased and propensity to flow increased as particle size decreased (51.7mJ/g versus 8.0mJ/g, and “free flowing” versus “highly free-flowing”). This large energy requirement for coarse sugar particles was attributed more to particle shape than composition, as the sharp edges of sugar can interlock and restrict movement through the sample. The starch-based results were validated in a particulate flow study involving the above model systems (corn meal, corn flour, wheat farina, and wheat flour) in a pilot-scale single screw extruder. Visualization data, obtained using a transparent plexiglass window during extrusion, confirmed that the flours exhibited higher flow energy requirements and a lower flow factor compared to coarser-particle size during extrusion, seen by the increased peak heights and barrel fill. Additionally, moisture changes were analyzed, showing an increase in energy required for starch-based materials as moisture increases and a decrease in energy for sucrose. Due to the hygroscopic nature of sucrose, moisture was absorbed more rapidly than starch products and the edges of individual particles softened, forming a soft solid. These physiochemical differences resulted in decreased energy requirements for sucrose as moisture was increased (51.7mJ/g to 13.6mJ/g), while corn meal and wheat farina yielded increased energy requirements (6.7mJ/g to 9.1mJ/g and 5.8mJ/g to 9.5mJ/g, respectively). Again, results of starch-based materials were validated using a plexiglass cover during extrusion, clearly showing an increase in barrel fill as moisture content increased for both materials, with corn meal flowing more readily than farina. Lastly, temperature of corn meal and farina was increased to show the difference in behavior of starch-based materials, where farina decreased in energy as temperature increased (14.4mJ/g to 12.1mJ/g ) while corn meal energy requirements increased (12.9mJ/g to 17.2mJ/g). With the results developed from these three experiments, and validated where physically possible, it was concluded that offline powder rheometry is a useful tool for predicting the behavior of food powders. These results were then developed into a computer-simulated model to allow for virtual and visual representation of the conveying action inside an enclosed steel barrel.

Orientador: João Sinézio de Carvalho Campos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T10:17:41Z (GMT). No. of bitstreams: 1 Almeida_RosemeiredosSantos_M.pdf: 1496479 bytes, checksum: b8bf05066c4483752cebde2f006e95c6 (MD5) Previous issue date: 2010 / Resumo: E bem conhecido o amplo uso de materiais poliméricos e o proporcional impacto que eles causam quando são descartados no meio ambiente, especialmente os "commodities" como Polipropileno (PP) e Polietileno (PE). Isso tem preocupado os cientistas, que cada vez mais procuram desenvolver tecnologias para o reaproveitamento desses materiais. Uma das técnicas existentes e o reprocessamento por meio de extrusoras e injetoras, cujos processos, no entanto, tendem a degradar o material, levando a alteração em suas propriedades mecânicas e reológicas. Tendo em vista o contexto apresentado, foi desenvolvido um estudo no qual se avaliou a influencia da velocidade de rotação da rosca no processo de extrusão do polipropileno (PP) virgem e material reciclado, proveniente do setup durante a produção de canudos para refrigerante e rebarbas da fabricação de fraldas descartáveis, absorventes em que existe uma pequena quantidade de polietileno (PE). Observou-se sob quatro diferentes rotações, a saber: 40, 80, 120 e 160 rpm e um mesmo perfil de temperatura ao longo de uma extrusora monorosca. Apos o processo de extrusão, realizado sob as condições citadas acima, injetaram-se corpos de prova para analise de propriedades mecânicas, reológicas e térmicas. Constatou-se que as diferentes rotações estudadas provocaram alterações na deformação máxima de ruptura na tração, sendo que para o material reciclado, a rotação de 160 rpm apresentou a maior alteração dentre as demais rotações estudadas / Abstract: It's well known the broad use of polymeric materials and the proportional impact they cause when discarded in the environment, especially the "commodities" known as polypropylene (PP) and Polyethylene (PE). This has worried scientists, who search to develop technology to recycle these materials. One of these techniques is the reprocessing by extrusion and injection molding, the processes, however, tend to degrade the material, leading to alteration in their mechanical and rheological properties. Considering the context presented, it was developed a study where we evaluated the influence of rotation speed of the screw in the extrusion of virgin polypropylene (PP) and material recycled obtained from soda straws and disposable diapers's burrs, where there are a small amount of polyethylene (PE). It was observed four different speeds, namely 40, 80, 120 and 160 rpm carried out in one temperature profile along a single screw extruder. After the extrusion process, conducted under the above conditions were injected samples for analysis of mechanical, rheological and thermal properties. It was found that the different rotations cause changes in rupture maximum tensile strain. The recycled material processed at 160 rpm has presented the greatest change among the studied rotations / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Este trabalho propõe contribuir no desenvolvimento do processo de extrusão para a produção de compósitos cimentícios, mediante metodologia que possibilite a obtenção de formulações extrudáveis utilizando cimento Portland de alta resistência inicial, sílica ativa, calcário, polpa de celulose de eucalipto, fibras de polipropileno e aditivos. Para isso, foram caracterizadas as matérias-primas como subsidio para as discussões. O efeito dos diferentes componentes da formulação no comportamento reológico da mistura foi avaliado utilizando reômetro extrusor. As propriedades físicas e mecânicas dos compósitos elaborados com combinações de calcário, sílica ativa e cimento foram modeladas estatisticamente com o propósito de estimar o comportamento das matrizes. A demanda de água dos sistemas cimentícios foi determinada experimentalmente e utilizada na extrusão das matrizes. Selecionada uma matriz, suas propriedades mecânicas e físicas foram modeladas, estatisticamente, com diferentes teores de polpa celulósica de eucalipto e fibras de polipropileno. As formulações com características desejadas foram avaliadas ao envelhecimento acelerado por 200 ciclos de imersão-secagem. Finalmente foi analisada a reprodutibilidade utilizando o módulo de Weibull para as formulações selecionadas. O estudo reológico constatou que as fibras de polipropileno apresentam os maiores aumentos nos valores dos parâmetros reológicos se comparados com os efeitos do calcário, sílica ou celulose de eucalipto, repercutindo em maiores pressões de extrusão. O incremento do modificador reológico hidroxipropilmetilcelulose reduz no compósito cimentício o módulo de ruptura mesmo que durante o processamento, promova o incremento da pressão de extrusão. Os modelos estatísticos empregados para modelar a matriz reforçada foram de maior complexidade e com menor coeficiente de determinação se comparados com os utilizados na modelagem das matrizes. O preço de mercado do fibrocimento é aproximadamente 64% menor do que os determinados utilizando unicamente os valores das matérias-primas e aditivos do fibrocimento extrudado no presente estudo. / This work intends to contribute in the development of the extrusion process for the production of cementitious composites, through methodology that makes it possible to obtain formulas using high resistance Portland cement, silica fume, limestone, eucalyptus pulp, polypropylene fibers and admixtures. With this intention, the raw materials were characterized as a support for the discussions. The effects of the different components of the formula on the rheological behavior of the mixture were evaluated using an extrusion rheometer. The physical and mechanical properties of the composites elaborated with the combinations of limestone, silica fume and cement were modeled statistically with the purpose of estimating the behavior of the matrix. The water demand of the cementitious systems was determined experimentally and used in the matrixes extrusion. After the Matrix Selection, their mechanical and physical properties were modeled statistically, with different pulp eucalyptus and polypropylene fibers quantities. The formulas with the expected characteristics were evaluated to the accelerated aging for 200 wet-drying cycles. Finally the reproducibility was analyzed using the Weibull module for the selected formulas. The rheological studies verified that the polypropylene fibers demonstrate the largest increase in the values of the rheological parameters when compared with the effects of the limestone, silica fume or eucalyptus pulp, inducing larger extrusion pressures. The increment of the rheological modifier hydroxypropyl methylcellulose decreases the module of rupture in the cementitious composite, and simultaneously during the process it promotes the increment of the extrusion pressure. The statistical models used to reinforce the matrix modeling were of large complexity and with smaller coefficient determination when compared to matrixes used for modeling. The fiber cement market price is approximately 64% smaller than the raw materials and admixtures used in extruded fiber cement in this study.

Introdução - Devido ao perfil de mortalidade e de danos patológicos associados, as doenças cardiovasculares são consideradas um sério problema de saúde pública. Níveis de colesterol plasmático elevados fazem parte dos fatores de risco mais importantes para o desenvolvimento dessas doenças. Pesquisas recentes demostraram que a proteína do feijão caupi promove a redução dos níveis de colesterol em hamsters e em seres humanos, possivelmente pela ação de peptídeos bioativos advindos da dieta. Entretanto, a via pela qual o colesterol é inibido por esses peptídeos, assim como os efeitos do processamento na ação biológica ainda são desconhecidos. Objetivo - Verificar a via de ação hipocolesterolêmica dos hidrolisados do feijão caupi e o efeito do processamento térmico nesta propriedade. Métodos - Parte da farinha integral foi submetida ao isolamento de proteína e o restante dos grãos foi submetido à cocção em autoclave e à extrusão. Após ser cozido em autoclave, o feijão cozido também teve sua proteína isolada. Posteriormente, a proteína isolada do feijão integral e do feijão cozido foi submetida à hidrólise in vitro. O processo de extrusão foi modelado em função da expansão dos extrusados segundo a metodologia de superfície de resposta. A farinha do feijão extrusado foi submetida à hidrólise enzimática in vitro sem isolamento prévio da proteína. Os três hidrolisados foram submetidos à ultrafiltração e a fração menor que 3 kDa foi utilizada nos ensaios de inibição da enzima 3-hidroxi-3-metilglutaril coenzima A redutase (HMGR) e no ensaio de inibição da solubilização micelar do colesterol para avaliar a ação dos hidrolisados na via hepática e na via entérica do metabolismo do colesterol respectivamente. Resultados - Os hidrolisados provenientes dos isolados proteicos apresentaram comportamentos semelhantes. Em doses mais elevadas de proteína (acima de 70 µg/mL), a inibição apresentou-se estável, por volta dos 75 por cento. Em relação ao hidrolisado da farinha de feijão extrusado, à medida que se aumenta a quantidade de proteína a capacidade inibitória diminui. Os hidrolisados foram capazes de inibir a solubilização micelar do colesterol de 5 a 39 por cento. O processamento térmico foi fator determinante para diminuir a solubilização do colesterol in vitro. Conclusão Os hidrolisados do feijão caupi são capazes de inibir a enzima HMGR e reduzir a solubilização micelar do colesterol in vitro, mesmo após o feijão ser processado termicamente. A capacidade dos hidrolisados de insolubilizar o colesterol foi melhorada pelo cozimento em autoclave e pela extrusão / Introduction- The cardiovascular diseases, due to mortality and associated pathological damage, are considered a serious public health problem. Elevated plasma cholesterol levels are part of the most important risk factors for the development of these diseases. Recent research indicated that Cowpea protein promotes the reduction of cholesterol levels in hamsters and humans, possibly by the action of bioactive peptides from the diet. However, the route by which cholesterol is inhibited by peptides, as well as the processing effects on biological action are still unknown. Objective - To verify the hypocholesterolemic pathway of hydrolyzed cowpea and the effect of thermal processing on this property. Methods - Part of wholemeal flour was subjected to isolation of protein, and the remaining of the grains was subjected to retort and extrusion cooking processes. After autoclaving the grain, protein was also isolated from the flour. Subsequently, the isolated protein from wholemeal and cooked flour was subjected to in vitro hydrolysis. The extrusion process was optimized according to response surface methodology using the expansion ratio of extrudates as the dependent variable. The extruded bean flour was subjected to in vitro enzymatic hydrolysis without the isolation of the protein. The three hydrolysates were subjected to ultrafiltration and and fractions smaller than 3 kDa was used for inhibition assays of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and for inhibition assay of micellar solubilization of cholesterol to evaluate their effect on the liver and enteral cholesterol metabolism respectively. Results - The hydrolysates from the protein isolates showed similar. At higher doses of protein (above 70 mg/mL), the inhibition was stable at around 75 per cent. Regarding the hydrolyzate of bean flour extruded as it increases the amount of protein inhibitory capacity decreases. The hydrolysates were able to inhibit the micellar solubilization of cholesterol between 5 and 39 per cent. The thermal processing was the determining factor to decrease the solubility of cholesterol in vitro. Conclusion The hydrolysates of cowpea are able to inhibit the enzyme HMGR micellar solubilization and reducing cholesterol in vitro, even after being thermally processed beans. The ability of hydrolysates insolubilize cholesterol was improved by cooking in an autoclave and by extrusion

Orientador: Yoon Kil Chang / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T21:12:19Z (GMT). No. of bitstreams: 1 Depieri_Matheus_M.pdf: 2073635 bytes, checksum: 4b24da7da4e4941973fd7a1a74858c5e (MD5) Previous issue date: 2004 / Resumo: O presente trabalho analisou a produção de pastas instantâneas feitas a partir de dois tipos de matérias-primas, a farinha de trigo comum e a semolina de trigo durum, utilizando o processo de extrusão termoplástica. O objetivo principal do trabalho foi comparar a qualidade dos dois tipos de pastas obtidos, já que pelo processo convencional de produção de massas alimentícias, a matéria-prima mais usada e que garante melhor qualidade às pastas é a semolina de trigo durum, que, por outro lado, apresenta um maior custo. Procurou-se, através do processo de extrusão, obter produtos de características semelhantes, mesmo usando uma matéria-prima de qualidade inferior e custo mais baixo, que é o caso da farinha de trigo comum. Para isso foi utilizado um extrusor termoplástico de rosca simples Brabender mod. 1014/2, seguindo um planejamento experimental do tipo composto central rotacional com 3 variáveis independentes, a temperatura na 2ª zona do extrusor (x1), umidade da mistura inicial (x2) e teor de emulsificante na mistura inicial (x3). Foram analisadas, além da composição centesimal e características reológicas das matérias-primas, as seguintes respostas para as pastas instantâneas obtidas: umidade, cor, tempo ótimo de cozimento, perda de sólidos na água de cozimento, ganho de peso, ganho de volume e textura (força máxima de ruptura e trabalho de ruptura). Foram obtidos os respectivos modelos matemáticos e as superfícies de resposta de cada parâmetro. Além disso, algumas amostras foram submetidas a testes de calorimetria de varredura diferencial, microscopia eletrônica de varredura e teste de difração de raios-X, a fim de se determinar, principalmente, o grau de gelatinização do amido nas amostras em cada condição de processo. As pastas instantâneas de melhor qualidade obtidas apresentaram tempo ótimo de cozimento de 1,5-2,0 minutos, perda mínima de sólidos na água de cozimento (1,5%), força de ruptura de 15-20 g e trabalho de ruptura em torno de 50 g. No caso da semolina de trigo durum, as condições de processo para se obter tais características seriam temperatura de 115°C, umidade da mistura inicial de 26% e teor de emulsificante de 1,0%. Já no caso da farinha de trigo comum, as condições de processo incluiriam temperatura de 105-110°C, umidade 24-25% e maior teor de emulsificante (1,15-1,5%). Micrografias, juntamente com análises de calorimetria diferencial de varredura (DSC) e difração de raios-X, evidenciaram um alto grau de gelatinização do amido e desnaturação protéica das amostras de pasta instantânea obtidas sob diferentes condições de processamento. Também foi verificada a formação de complexos amilose-emulsificante, apresentando forte influência nas características de cozimento e qualidade das pastas obtidas / Abstract: This present work analyzed the production of instantaneous pasta made from two different types of raw materials, flour of common wheat and semolina of durum wheat, using a thermoplastic extrusion process. The main purpose was to compare the quality of the two types of pasta, because through conventional process, pastas are usually made from semolina of durum wheat that guarantees a better quality but, on the other hand, shows a higher cost than other varieties of wheat. It had been tried, through cooking extrusion process, to obtain products with similar characteristics, even using a poorer quality and lower cost raw material, as the flour of common wheat. So, it was used a Brabender single screw extruder, model 1014/2, following a rotatable central-composite design with 3 independent variables: the temperature in the 2nd zone of the extruder (x1), moisture of initial mixture (x2) and rate of emulsifier in the initial mixture (x3). Besides the analysis of composition and rheological characteristics of raw materials, it had been determined the following answers for obtained pastas: moisture content, color parameters, cooking time, cooking loss, weight and volume gain after rehydration, and texture (including maximum force of rupture and work of rupture). It was obtained the mathematic models and surface response for each answer. Some experiments underwent to tests of differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray diffraction to determine, mainly, the extent of gelatinization in pastas for each different process conditions. High quality obtained pastas presented cooking time of 1,5-2,0 minutes, minimum cooking loss (1,5%), force of rupture of 15-20 g and work of rupture around 50 g. In the case of durum wheat semolina, the conditions of process to get such characteristics were 115°C, 26% of initial moisture and 1,0% of emulsifier. No longer case of common wheat flour, the process conditions included temperature of 105-110°C, moisture 24-25% and high percentage of emulsifier (1,15-1,5%). Micrographs, with DSC and X-ray diffraction analysis, showed a high level of starch gelatinization and protein denaturation in pastas produced under different process conditions. It was also verified the formation of amylose-emulsifier complexes, those strongly influenced the pasta quality and cooking characteristics / Mestrado / Mestre em Tecnologia de Alimentos

Dans l’industrie de la mise en forme des matériaux métalliques, le frottement joue un rôle très important. Cependant, il est difficile à contrôler totalement, notamment dans les procédés complexes où le taux de nouvelles surfaces générées lors de la déformation plastique est important. La thèse propose d’identifier par analyse inverse les propriétés tribologiques du matériau, directement à partir de la courbe donnant la force en fonction du déplacement pour un procédé d'extrusion directe. La conception d’une filière d’extrusion, avec des dimensions optimales pour maximiser l’influence du frottement a été faite à l’aide de calculs analytiques en se basant sur des critères particuliers tels que: la capacité maximale de la presse, la maximisation de la longueur de frottement, le rapport entre la puissance de frottement et la puissance de déformation et la limite du taux de réduction pour éviter l’endommagement du matériau. Comme dans le procédé d’extrusion il existe un certain couplage entre l’influence des paramètres rhéologiques et des paramètres tribologiques, des tests de compression d’éprouvettes «haltères» ont été réalisés dans une première étape afin d’identifier la loi de comportement rhéologique du matériau. La conception du test proposé a été validée par des simulations numériques avec FORGE2®. Les simulations numériques ont été également effectuées pour analyser la sensibilité des paramètres rhéologiques et tribologiques du matériau sur la force d’extrusion. L’influence de la géométrie de la filière sur la courbe de force a été examinée en détail. Une campagne d’essais a été réalisée pour l’alliage d’aluminium AA5083. La loi de comportement du matériau a été en conséquence identifiée par analyse inverse à partir de la courbe expérimentale donnant la force de compression des éprouvettes «haltères». Dans une deuxième étape, les propriétés tribologiques du matériau pour différents modèles de frottement ont été ensuite identifiées par analyse inverse à partir de la courbe donnant la force d’extrusion. La méthode d’identification par analyse inverse a été enfin validée par la simulation d’un procédé industriel d’extrusion. La campagne d’études expérimentales a été complétée par la caractérisation du matériau par des mesures de dureté, des mesures de diffraction des rayons X et des mesures de diffraction des électrons rétrodiffusés (EBSD) afin de mettre en évidence l’évolution de la surface des pièces après la déformation plastique. Les résultats indiquent que le frottement a une influence importante sur l’évolution des orientations cristallines de la surface du matériau extrudé. / In the industry of metal forming, friction plays a very important role. However, it is difficult to control completely this phenomenon, especially in the complex processes where the rate of the new surface generated during the plastic deformation is important. The thesis proposes to identify by inverse analysis the tribological properties of material, directly starting from the curve of the load versus the displacement of a direct extrusion process. The design of an extrusion die, with optimal dimensions to maximize the influence of friction, was carried out using analytical calculations based on particular criteria such as: the maximum capacity of the press, the maximization of the friction length and of the ratio between the friction power and the deformation power, the limit of the reduction rate to avoid damage of the material. Since in the extrusion process there is a certain coupling between the influence of the rheological parameters and the tribological parameters, compression tests using "dumbbells" specimens were carried out in a first stage in order to identify the rheological behavior law of the material. The design of the proposed test has been validated by numerical simulations using FORGE2®. The numerical simulations were also performed in order to analyze the sensitivity of rheological and tribological parameters of the material on the extrusion load. The influence of the geometry of the die on the extrusion load curve has been examined in detail. A campaign of tests was carried out for the AA5083 aluminum alloy. The behavior law of the material was consequently identified by inverse analysis starting from the experimental load curve of compression tests using "dumbbells" specimens. In a second step, the tribological properties of the material for different friction models were then identified by inverse analysis starting from the extrusion load curve. The method of identification by inverse analysis was finally validated by the simulation of an industrial extrusion process. The campaign of experimental studies has been completed by the characterization of the material by measurements of hardness, X-ray diffraction measurements and electron backscattered diffraction (EBSD) measurements in order to highlight the evolution of the surface of the extruded specimen after the plastic deformation. The results indicate that friction has an important influence on the evolution of crystal orientations of the surface of the extruded material.