La thèse vise l'application du concept de bioraffinerie (extraction, fractionnement, séparation de composés à partir de biomasse avant transformation ultérieure), via le développement d'étapes de production destinées à être associées en un procédé continu. La complexité du solide nécessite une étape de prétraitement effectuée avec une technologie à faible impact environnemental et l'eau subcritique est déjà utilisée comme solvant d'extraction des produits naturels, en sus de leur hydrolyse. Ces travaux ont porté sur l'hydrolyse de polysaccharides (son de riz) et de triacylglycérols (TAG, huile de tournesol) choisis comme modèles. Les caractéristiques de l'eau subcritique (produit ionique, constante diélectrique) mise en œuvre en réacteurs à circulation construits dans ce but, ont permis l'hydrolyse quasi-totale de l'hémicellulose et des TAG. L'addition de CO2 et donc d'acide carbonique a eu un effet positif sur l'hydrolyse de l'hémicellulose. Les acides gras libres résultant de l'hydrolyse ont été estérifiés en ester éthyliques en présence d'une lipase en réacteur continu en milieu CO2 supercritique, avec un taux de synthèse de 95%. Les cinétiques des réactions ci-dessus d'hydrolyse et d'estérification ont été étudiées. La complexité des interactions entre les nombreux paramètres mis en jeu a conduit à appliquer des méthodes de plans d'expérience. Ces méthodes ont été validées avec succès avec les données expérimentales, montrant ainsi leur utilité dans le développement de procédés. La question importante de la solubilité des extractibles dans l'eau subcritique a été traitée et une méthode de prédiction mise au point et validée avec succès avec les données expérimentales. En conclusion, ce travail montre la possibilité d'appliquer le concept novateur de la Bioraffinerie Intégrée en réacteur continu avec des fluides sub- ou supercritique, contrairement à leur mise en œuvre actuelle en réacteur fermé, pour la production de composés commercialisables. / This work addresses the integrated biorefining concept (extraction, fractionation, separation of compounds from biomass prior to further transformation) by developing discrete units with the ultimate objective of coupling them to enable a continuous flow configuration. Due to the complexity of solid, there is a need for a sustainable and environmentally friendly pre-treatment technology. Sub-critical water has been used as a solvent for extracting natural compounds in addition to hydrolysis. This work investigated the hydrolysis of carbohydrates (rice bran) and triacylglycerols (TAG; sunflower oil) chosen as models. The attribute of subcritical water (ion product and dielectric constant) in continuous flow reactors built for the purpose, allowed almost quantitative hydrolysis of hemicellulose and TAG. The effect of adding CO2 and therefore carbonic acid was positive on the hydrolysis of hemicellulose. Further, free fatty acids were transformed to ethyl esters using lipase within continuous flow super critical CO2 resulting in 95% yield. The hydrolysis and esterification reaction kinetics were studied. To address the complex interplay between multiple processing parameters response surface methodologies (RSM) were developed. Using the empirical data the models were successfully validated, therefore showing the utility of the RSM to assist process development. The important question of solubility of extractible in subcritical water was also addressed, through the development of a prediction method, validated with experimental data. In summary this work shows the possibility of applying the innovative Integrated Biorefining concept under continuous flow conditions -instead of the current application under batch conditions- for producing valuable compounds.

Des agrégats à base des boues de phosphate de la zone de Gantour ( Youssoufia,Maroc) sont cuits à des températures comprises entre 900 et 1200°C, et examinés par différentes techniques (DRX, MEB, analyses thermique et dilatométrique, et spectroscopie d’impédance). Les propriétés physiques des agrégats (retrait, absorption d’eau et résistance à la compression) sont mesurées et corrélées, dans certains cas, aux facteurs expérimentaux(température, temps de cuisson, teneur de l’additif), et ce en utilisant la méthodologie de la recherche expérimentale.Les agrégats amendés à l’argile smectitique sont le siège de formation de la gehlénite. Dans ce cas, la fluorapatite a partiellement résisté au traitement thermique, et a été le siège d’une ségrégation localisée. Les mesures d'impédance ont bien mis en évidence l'étape principale du frittage, lequel s’est produit par écoulement de la masse fondue. En se basant sur les valeurs de la densité, les granulats cuits à 900 et à 1100°C pouvaient bien être considérés comme des agrégats légers.Les études menées sur les agrégats des mélanges : argile kaolinitique-boue, cendre boue,et argile kaolinitique-cendre-boue ont montré la présence de la labradorite, et d’une masse fondue, qui semblait se former, entre autres, de la fusion de la fluorapatite. Par ailleurs,l'utilisation de la méthodologie de la recherche expérimentale a permis d'évaluer le poids des effets des facteurs expérimentaux sur les propriétés physiques des agrégats. Des granulats légers (1,02 < densité < 2,1 g/cm3) et résistants sont préparés avec succès dans les conditions expérimentales adoptées. Les granulats ayant le meilleur rapport résistance / densité sont ceux du mélange ternaire.Concernant le volet application, les résultats ont montré que l’utilisation des agrégats en construction est possible et que l’association d’agrégats légers au sol a permis d’activer la croissance des plants de la luzerne. D’un autre côté, l'absorption du phosphore par les racines(1,45 mg/g maximum) des plantes était meilleure dans le cas du mélange contenant de l’argile. / Phosphate sludge generated from beneficiation plants of Moroccan phosphate rocks was investigated at the range [900-1200°C] by X-ray diffraction, scanning electron microscopy, thermal analysis dilatometric analysis and impedance spectroscopy. Mixtures of the phosphates ludge and amendments such as a swelling clay (up to 30 wt.% of the clay), a kaolinitic clay (up to 40 wt.% of the sludge) and a fly ash (65.5 wt.% of the ash) were investigated and their properties (shrinkage, density, water absorption and compressive strength) were measured as a function of temperature and clay addition. The results showed that gehlénite neoformed from lime of decomposed carbonates and breakdown products of clay minerals in the first mixture while labradorite/anorthite was the only neoformed phase in the other blends. Also fluoroapatite (original mineral) resisted heating until fusion in almost samples. A new approach based on the methodology of the experimental design was adopted to assess the effect of the processing factors on the studied properties. The measured properties were mainly controlled by temperature, and the effect of clay addition was less regular. Considering the mixtures densities lightweight agglomerates can be produced at specific conditions. On the other hand, the release ability of phosphorus by LWAs in the presence ofalfalfa plants has been performed. It was found that due to the release of phosphorus by soil embedded pellets the growth of alfalfa plants improved. The sintering process of blends of phosphate sludge and a naturally occurring clay material (0-30 wt.%) was investigated in the range 650-1100°C by using impedance spectroscopy. The results showed that the sintering process was effective between 750 and 1000°C and occurred by melt flow.

A estabilidade oxidativa em óleos e emulsões é influenciada pela ação simultânea de diversos fatores. Entretanto, a avaliação do efeito antioxidante de novos compostos tem sido conduzida utilizando-se valores fixos para esses fatores. Portanto, o objetivo deste estudo foi aplicar técnicas fatoriais para desenvolver modelos de oxidação lipídica nos quais os principais fatores pudessem variar simultaneamente. A oxidação de óleo de linhaça removido de seus componentes minoritários, determinada pela concentração de hidroperóxidos e malonaldeído (TBARS), foi avaliada em função da variação conjunta da temperatura (40 - 60 oC), concentração de ferro (0,0 - 1,0 mmol/L FeSO47H2O) e de ascorbil palmitato (0,0 - 1,5 mmol/L). Os maiores valores observados para os marcadores foram obtidos a 40oC, sendo altamente dependentes da relação \"ferro / ascorbil palmitato\". Adicionando-se 1,4707 mmol/L de ferro e 1,5839 mmol/L de ascorbil palmitato, a amplitude de formação de hidroperóxidos aumentou em 57%. Uma emulsão foi preparada com 1% do mesmo óleo de linhaça removido de seus componentes minoritários, utilizando-se um emulsificante aniônico sob alta pressão. A variação da temperatura, pH e concentração de ferro, cobre, ácido ascórbico, ascorbil palmitato e cloreto de sódio nos marcadores químicos da oxidação (hidroperóxidos e TBARS) foi avaliada através de um planejamento fracionário do tipo Plackett-Burman para seleção de variáveis. A seguir, o efeito das concentrações de ferro (0,0 - 1,0 mmol/L FeSO47H2O), ácido ascórbico (0,0 - 2,0 mmol/L) e pH (3,0 - 7,0) na estabilidade oxidativa das emulsões foi avaliado utilizando-se um Delineamento Composto Central. Os maiores valores dos marcadores foram obtidos adicionando-se 0,885 mmol/L de ferro e 1,700 mmol/L de ácido ascórbico à emulsão mantida a 30ºC sob pH 5,51. A atividade antioxidante de seis compostos foi avaliada em ambos os modelos (óleo puro e emulsão), sendo que uma melhor discriminação entre as amostras foi observada nos sistemas otimizados. A utilização de técnicas fatoriais mostrou-se eficiente na avaliação conjunta de vários fatores que influenciam a estabilidade oxidativa de óleos e emulsões, e proporcionou um melhor poder de discriminação na atividade antioxidante de compostos naturais e artificiais. / The oxidative stability in bulk oils and emulsions is affected by many factors. However, assessment of the antioxidant effect of new compounds has been carried out under fixed conditions. Thus, the objective of this study was to apply factorial techniques to develop lipid oxidation models in which the main factors vary simultaneously. Oxidation of flaxseed oil stripped of its minor components determined by the concentration of hydroperoxides and malonaldehyde (TBARS) was evaluated according to the combined variation of temperature (40 - 60 oC), iron concentration (0,0 - 1,0 mmol/L FeSO47H2O) and ascorbyl palmitate concentration (0,0 - 1,5 mmol/L). The highest observed values to these markers were obtained at 40oC, being greatly dependent on the \"iron / ascorbyl palmitate\" ratio. Addition of 1,4707 mmol/L of iron and 1,5839 mmol/L of ascorbyl palmitate increased the hydroperoxide formation by 57%. An emulsion was prepared with 1% of the same stripped flaxseed oil and an anionic emulsifier under high pressure. The variation of temperature, pH and iron, copper, ascorbic acid, ascorbyl palmitate and sodium chloride concentration on the chemical markers of oxidation (hydroperoxides and TBARS) was evaluated using a Plackett-Burman design to screen the variables. Following, the effect of iron concentration (0,0 - 1,0 mmol/L FeSO47H2O), ascorbyl palmitate concentration (0,0 - 2,0 mmol/L) and pH (3.0 - 7,0) on the oxidative stability of the emulsion was evaluated using a Central Composite Design. The highest observed values to these markers were obtained adding 0,885 mmol/L of iron and 1,700 mmol/L of ascorbic acid to the emulsion under 30ºC and pH 5,51. The antioxidant activity of six compounds was evaluated using both models (bulk oil and emulsion), in which a better discrimination was observed for the samples in the optimized systems. The application of factorial techniques was efficient on the joint assessment of several factors that affect the oxidative stability of oils and emulsions, and provided a better discrimination power on the antioxidant activity of natural and artificial compounds.

A oxidação lipídica é uma das causas mais importantes que levam à perda das qualidades nutricionais e sensoriais dos alimentos que possuem lipídios em sua composição, diminuindo assim sua vida de útil e provocando rejeição por parte dos consumidores. Considerando estes aspectos, a indústria de alimentos faz o uso de compostos antioxidantes, capazes de retardar a oxidação. A maioria dos antioxidantes utilizados atualmente é de origem sintética, que apresentam restrições quanto ao seu uso em alimentos que variam de país para país. Tais restrições fundamentam-se em aspectos relacionados ao impacto dos antioxidantes sintéticos sobre a saúde do consumidor. Em consequência, na última década ocorreu um aumento considerável no número de pesquisas que abordam uso de antioxidantes obtidos de fontes naturais em alimentos, a fim de identificar fontes promissoras desses compostos. Com esse objetivo, o presente trabalho avaliou a atividade antioxidante de extratos hidroalcoólicos de duas amostras de frutos de murtilla (Ugni molinae Turcz.), silvestre e a cultivar melhorada 14-4, por meio da aplicação de testes in vitro e em sistema modelo a base de óleo de soja. A aplicação da Metodologia de Superfície de Resposta permitiu a seleção da melhor condição operacional para a produção de extratos hidroalcoólicos a partir dos frutos desidratados. A condição que apresentou maior eficiência para recuperação dos compostos fenólicos foi o emprego de etanol 49,5% (v/v) a temperatura de 30ºC, sendo que para a murtilla silvestre o teor foi de 18,39 mg GAE/ g matéria seca e 26,14 mg GAE/ g matéria seca para a cultivar 14-4. As análises de ABTS e DDPH foram realizadas nos extratos produzidos nas condições otimizadas e os resultados obtidos foram 471?mol TEAC/g matéria seca de murtilla silvestre e 881,84 ?mol TEAC/g matéria seca de murtilla 14-4 para o ABTS e 229,59 ?mol TEAC/g matéria seca de murtilla silvestre e 403 ?mol TEAC/g matéria seca de murtilla 14-4 para o DPPH. Análise cromatográfica em fase gasosa acoplada a detector de massas foi realizada visando a identificação dos compostos presentes nos extratos, após derivatização das amostras. Foram identificados componentes como quercetina, epicatequina, ácido gálico, ácido benzoico e ácido hidrocafeico, que possuem atividade antioxidante comprovada. Os extratos potencialmente antioxidantes foram aplicados em sistema modelo (50, 100, 150 e 200 mg kg-1) com óleo insaturado (óleo refinado de soja, sem adição de antioxidantes sintéticos) em condições aceleradas: Teste de estufa (Schaal Oven Test) e Rancimat. No teste de Estufa e no Rancimat as concentrações que apresentaram melhor poder antioxidante foram a de 150 e 200 mg kg-1 para as duas amostras de extratos de frutos de murtilla analisadas. Os resultados de análise sensorial com provadores treinados demonstraram que não houve diferenças estatisticamente significativas entre as concentrações dos extratos adicionados ao óleo de soja submetido à oxidação em estufa, sendo que o TBHQ demonstrou a melhor aceitação. Contudo, considerando as observações feitas pelos provadores é possível afirmar que após as 96 horas de estufa, o odor de ranço foi mascarado pelo odor agradável do extrato dos frutos. / Lipid oxidation is one of the most important causes that promote the loss of nutritional and sensory qualities of foods containing lipids in their composition, thus decreasing their shelf life and causing rejection by consumers. Considering theses aspects, the food industry uses antioxidant compounds that are able to inhibit or retard oxidation. However most of antioxidants currently used are synthetic, with restrictions as to its use in lipid-based foods that vary from country to country. Such restrictions are based on aspects related to the impact of synthetic antioxidants on consumer\'s health. Due to this, in the last decade there was an increase in the number of researches that focuses on using natural sources of antioxidants, such as vegetables, fruits, among others, in food, in order to identify potential sources of antioxidants. With this objective, the present study evaluated the antioxidant activity of hydroalcoholic extracts of two varieties of murtilla\'s fruits (Ugni molinae Turcz.), wild and 14-4, through the application of in vitro assays and in a model system based on soybean oil. The application of response surfaces methodology allowed the selection of the optimal operating condition for the production of hydroethanolic extracts from dried fruit. The total phenolic compounds were determined for evaluation of extracts\' antioxidant activity and adjustment of mathematical models. The condition with the highest phenolic content was extracted using ethanol 49,5% (v/v) and temperature at 30°C, the content for the wild murtilla was 18,39 mg GAE/g dry matter and 26,14 mg GAE/g dry sample for 14-4. The ABTS and DDPH analyses were proceeded with selected optimization extracts and the results were 471?mol TEAC/g dry sample of wild murtilla and 881,84 ?mol TEAC/g dry sample of 14-4 murtilla for ABTS and 229,59 ?mol TEAC/g dry sample of wild murtilla and 403 ?mol TEAC/g dry sample of 14-4 murtilla for DDPH. The analysis by gas chromatography-mass detector was performed for the identification of compounds presents in the extracts after derivatization of the samples. Were identified compounds as quercetin, epicatechin, gallic acid, benzoic acid and hidrocafeico that have proven antioxidant activity. The extracts potentially antioxidants were applied to the model system in increasing doses (50, 100, 150 and 200 mg kg-1) with unsaturated oil (refined soybean oil without addition of synthetic antioxidants) under accelerated conditions: Oven Test (Schaal Oven Test) and Rancimat. Concentrations that better presented antioxidant power were 150 and 200 mg kg-1for both of murtilla samples. Sensory results showed that there was no statistically significant difference among the concentrations of the extracts, and TBHQ showed a better acceptance by the trained panel. However, considering the comments made by the tasters is possible to affirm that after 96 hours of oven, the rancid odor is masked by the pleasant odor of the fruit.

A enzima lipoxigenase através da farinha integral de soja é amplamente utilizada na panificação com objetivos de branqueamento e melhora da reologia. Com base nesse pressuposto, o objetivo inicial deste estudo foi de observar a ação oxidante dessa enzima na presença de dois outros oxidantes (ácido ascórbico e peróxido de benzoíla) nas propriedades reológicas e sensoriais de pães. Sete misturas com diferentes combinações dos três compostos foram elaboradas utilizando-se um delineamento experimental do tipo \"centroide-simplex\", sendo aplicadas à farinha de trigo para o preparo de pães. A enzima apresentou sinergia com o ácido ascórbico na elasticidade da massa, sugerindo uma inter-relação bioquímica entre os dois compostos no fortalecimento da matriz protéica do glúten. A mesma sinergia entre a lipoxigenase da soja e o acido ascórbico foi observada na redução da tonalidade amarela dos pães medida instrumentalmente. A partir desses resultados, buscou-se avaliar a ação da enzima frente a variações tanto na força da farinha como no tempo de fermentação, reproduzindo as condições reais de processamento. Desta vez, um planejamento experimental do tipo Box-Behnken com três fatores (atividade da enzima, força da farinha e tempo de fermentação) em três níveis de variação, foi aplicado no preparo das amostras. Os resultados mostraram que a lipoxigenase da soja (fração 1) é uma enzima oxidante de ação rápida e seu efeito no branqueamento dos carotenóides da farinha de trigo exibiu interação positiva tanto com a força da farinha como o tempo de fermentação. Respostas reológicas e sensoriais decorrentes da ação conjunta de diferentes oxidantes e condições de processamento em pães foram pela primeira vez descritas através de modelos polinomiais com capacidade preditiva. / Soy lipoxygenase enzyme through soy flour is widely used in breadmaking for bleaching and rheological improvement. Based on this fact, the initial objective of this study was to observe the enzymes\' action in the presence of two other oxidants (ascorbic acid and benzoyl peroxide) in the rheological and sensory properties of breads. Seven mixtures with different combinations of the three compounds were prepared using a \"centroid-simplex\" design and applied to wheat flour for breadmaking. The enzyme showed synergism with ascorbic acid in the dough elasticity suggesting a biochemical interrelation between the two compounds in strengthening the gluten protein matrix. The same synergy between soy lipoxygenase and ascorbic acid was observed with the yellow hue reduction of breads measured instrumentally. From these results, the enzyme action was evaluated with wheat strength and proofing time variations reproducing real processing conditions. This time, a Box-Behnken experimental design with three factors (enzyme activity, wheat strength and proofing time), and three variation levels were applied in the sample preparation. The results showed that soy lipoxygenase (type 1) is a fast-acting oxidizing enzyme and its bleaching effect on wheat flour carotenoid exhibited a positive interaction with wheat strength and proofing time. Rheological and sensory results attributed to the combined action of the different oxidants and breadmaking conditions were for the first time described through polynomial models with predictive capacity.

Made available in DSpace on 2014-06-11T19:31:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-07-03Bitstream added on 2014-06-13T20:21:44Z : No. of bitstreams: 1 ernandes_fmpg_dr_sjrp.pdf: 1963066 bytes, checksum: 42dcae2ecfe9dfb358788c6490a13653 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O principal produto da fermentação de açúcares por Zymomonas mobilis é o etanol quando glicose e frutose são utilizadas como fontes de carbono. Entretanto, quando sacarose é empregada na fermentação, o rendimento do etanol diminui devido à formação de subprodutos como levana, sorbitol, acetaldeído, ácido acético, pequenas quantidades de alguns álcoois superiores e fenol. A utilização de produtos agroindustriais, como o caldo e melaço de cana-deaçúcar, é uma alternativa para reduzir o custo final dos produtos de fermentação devido à disponibilidade de aquisição e composição química desses substratos. Este trabalho teve como objetivo utilizar substratos alternativos e otimizar as condições de fermentação para a produção de etanol, levana e sorbitol por Zymomonas mobilis CCT 4494. Também foi considerado o efeito da variação do substrato e de sais minerais adicionados nos meios de produção (sintético, caldo e melaços de cana-de-açúcar). Para a obtenção dos produtos de fermentação, foi aplicada a metodologia de superfície de resposta, seguindo um planejamento fatorial do tipo 27-2, de acordo com o modelo proposto por Box e Hunter, onde as variáveis independentes estudadas foram: pH inicial do meio de cultivo, temperatura de incubação, concentração do substrato e efeito da adição de KCl, K2SO4, MgSO4, CaCl2. Durante a realização das fermentações foi observado que a bactéria Zymomonas mobilis CCT 4494 se adaptou nos meios de fermentação contendo altas concentrações de sacarose e suportou a variação do pH e da temperatura de fermentação. O aumento da concentração da fonte de carbono favoreceu a formação dos produtos levana e etanol, entretanto, não houve produção de sorbitol. O meio sintético proporcionou maior rendimento de levana e etanol, enquanto que, os meios alternativos caldo e melaços de cana-de-açúcar... / The main product from fermentation of sugars by Zymomonas mobilis is ethanol when glucose and fructose are used as carbon sources. However, when sucrose is used in the fermentation medium, ethanol yield decreases due to the formation of by-products such as levan, sorbitol, acetaldehyde, acetic acid, small amounts of some superior alcohols and phenol. The use of agro industrial by products, such as sugarcane juice and molasses, is an alternative to reduce the final cost of fermentation products due to the constant availability and to the chemical composition of these by substrates. This study had the aim of using alternative substrates and of optimizing fermentation conditions for the production of ethanol, levan and sorbitol by Zymomonas mobilis CCT 4494. The effect of variation of substrate and mineral salts added to the production media (synthetic, sugarcane juice and molasses) was also considered. To obtain the fermentation products, response surface methodology was employed, following a 27-2 factorial planning, according to the model proposed by Box and Hunter, where the independent variables studied were: initial medium pH, incubation temperature, substrate concentration and effect of the addition of KCl, K2SO4, MgSO4, CaCl2. During the fermentations, it was noted that the bacteria Zymomonas mobilis CCT 4494 well adapted in the media containing high concentrations of sucrose and tolerated pH and temperature variations. The increase of carbon source concentration favored the formation of levan and ethanol, however, there was no sorbitol production. The synthetic medium offered higher levan and ethanol yield, whereas alternative media sugarcane juice and molasses, favored cellular growth. Among the independent variables analyzed with the best medium (synthetic) for biosynthesis of the biopolymer and ethanol, the ones that significantly (p<0.05) affected were KCl, K2SO4, CaCl2... (Complete abstract click electronic access below)

A estabilidade oxidativa em óleos e emulsões é influenciada pela ação simultânea de diversos fatores. Entretanto, a avaliação do efeito antioxidante de novos compostos tem sido conduzida utilizando-se valores fixos para esses fatores. Portanto, o objetivo deste estudo foi aplicar técnicas fatoriais para desenvolver modelos de oxidação lipídica nos quais os principais fatores pudessem variar simultaneamente. A oxidação de óleo de linhaça removido de seus componentes minoritários, determinada pela concentração de hidroperóxidos e malonaldeído (TBARS), foi avaliada em função da variação conjunta da temperatura (40 - 60 oC), concentração de ferro (0,0 - 1,0 mmol/L FeSO47H2O) e de ascorbil palmitato (0,0 - 1,5 mmol/L). Os maiores valores observados para os marcadores foram obtidos a 40oC, sendo altamente dependentes da relação \"ferro / ascorbil palmitato\". Adicionando-se 1,4707 mmol/L de ferro e 1,5839 mmol/L de ascorbil palmitato, a amplitude de formação de hidroperóxidos aumentou em 57%. Uma emulsão foi preparada com 1% do mesmo óleo de linhaça removido de seus componentes minoritários, utilizando-se um emulsificante aniônico sob alta pressão. A variação da temperatura, pH e concentração de ferro, cobre, ácido ascórbico, ascorbil palmitato e cloreto de sódio nos marcadores químicos da oxidação (hidroperóxidos e TBARS) foi avaliada através de um planejamento fracionário do tipo Plackett-Burman para seleção de variáveis. A seguir, o efeito das concentrações de ferro (0,0 - 1,0 mmol/L FeSO47H2O), ácido ascórbico (0,0 - 2,0 mmol/L) e pH (3,0 - 7,0) na estabilidade oxidativa das emulsões foi avaliado utilizando-se um Delineamento Composto Central. Os maiores valores dos marcadores foram obtidos adicionando-se 0,885 mmol/L de ferro e 1,700 mmol/L de ácido ascórbico à emulsão mantida a 30ºC sob pH 5,51. A atividade antioxidante de seis compostos foi avaliada em ambos os modelos (óleo puro e emulsão), sendo que uma melhor discriminação entre as amostras foi observada nos sistemas otimizados. A utilização de técnicas fatoriais mostrou-se eficiente na avaliação conjunta de vários fatores que influenciam a estabilidade oxidativa de óleos e emulsões, e proporcionou um melhor poder de discriminação na atividade antioxidante de compostos naturais e artificiais. / The oxidative stability in bulk oils and emulsions is affected by many factors. However, assessment of the antioxidant effect of new compounds has been carried out under fixed conditions. Thus, the objective of this study was to apply factorial techniques to develop lipid oxidation models in which the main factors vary simultaneously. Oxidation of flaxseed oil stripped of its minor components determined by the concentration of hydroperoxides and malonaldehyde (TBARS) was evaluated according to the combined variation of temperature (40 - 60 oC), iron concentration (0,0 - 1,0 mmol/L FeSO47H2O) and ascorbyl palmitate concentration (0,0 - 1,5 mmol/L). The highest observed values to these markers were obtained at 40oC, being greatly dependent on the \"iron / ascorbyl palmitate\" ratio. Addition of 1,4707 mmol/L of iron and 1,5839 mmol/L of ascorbyl palmitate increased the hydroperoxide formation by 57%. An emulsion was prepared with 1% of the same stripped flaxseed oil and an anionic emulsifier under high pressure. The variation of temperature, pH and iron, copper, ascorbic acid, ascorbyl palmitate and sodium chloride concentration on the chemical markers of oxidation (hydroperoxides and TBARS) was evaluated using a Plackett-Burman design to screen the variables. Following, the effect of iron concentration (0,0 - 1,0 mmol/L FeSO47H2O), ascorbyl palmitate concentration (0,0 - 2,0 mmol/L) and pH (3.0 - 7,0) on the oxidative stability of the emulsion was evaluated using a Central Composite Design. The highest observed values to these markers were obtained adding 0,885 mmol/L of iron and 1,700 mmol/L of ascorbic acid to the emulsion under 30ºC and pH 5,51. The antioxidant activity of six compounds was evaluated using both models (bulk oil and emulsion), in which a better discrimination was observed for the samples in the optimized systems. The application of factorial techniques was efficient on the joint assessment of several factors that affect the oxidative stability of oils and emulsions, and provided a better discrimination power on the antioxidant activity of natural and artificial compounds.

<p>Cilj ovog rada je ispitivanje uticaja procesnih<br />parametara (transmembranski pritisak, protok i<br />koncentracija suspenzije) na vrednost fluksa<br />permeata, sa i bez prisustva statičkog me&scaron;ača,<br />tokom procesa mikrofiltracije suspenzija<br />p&scaron;eničnog skroba na keramičkim membranama<br />različitih veličina pora (200 nm i 500 nm).<br />Mikrofiltracija je izvođena u uslovima<br />recirkulacije i koncentrisanja napojne suspenzije.<br />Za modelovanje zavisnosti procesa mikrofiltracije<br />suspenzija skroba od procesnih parametara<br />primenjen je postupak odzivne povr&scaron;ine.<br />Ispitivanjem mikrofiltracije suspenzija p&scaron;eničnog<br />skroba na membranama sa različitim srednjim<br />prečnikom pora (200 i 500 nm) uočeno je da sa<br />povećanjem veličine pora vrednost fluksa<br />permeata opada.<br />U posmatranom eksperimentalnom opsegu<br />procesnih parametara postignuto je relativno<br />povećanje stacionarnog fluksa od 25% do 50% u<br />uslovima recirkulacije napojne suspenzije, dok je<br />u uslovima koncentrisanja napojne suspenzije<br />relativno povećanje srednjeg fluksa iznosilo od<br />20% do 80%. Porast fluksa do kojeg dolazi<br />postavljanjem statičkog me&scaron;ača u kanal membrane</p><p>uslovljen je uspostavljanjem turbulentnih uslova<br />proticanja i karakterističnog kretanja fluida duž<br />kanala membrane, koja je posledica<br />karakterističnog povezivanja helikoidnih<br />elemenata Kenics statičkog me&scaron;ača.<br />Kako u uslovima recirkulacije napojne sme&scaron;e,<br />tako i u uslovima koncentrisanja, vrednost<br />relativne specifične potro&scaron;nje energije zavisi skoro<br />isključivo od vrednosti protoka napojne sme&scaron;e. Sa<br />povećanjem protoka specifična potro&scaron;nja energije<br />u prisustvu statičkog me&scaron;ača naglo raste i<br />relativno povećanje protoka nije dovoljno da bi<br />kompenzovalo gubitak hidrauličke snage. U<br />opsegu protoka od 80 do 100 L/h su obezbeđene<br />pozitivne vrednosti relativne promene specifične<br />potro&scaron;nje energije, te je upotreba statičkog me&scaron;ača<br />opravdana sa ekonomskog aspekta.<br />Optimizacija eksperimentalnih uslova urađena je<br />postupkom istovremene maksimizacije fluksa<br />permeata u sistemima sa statičkim me&scaron;ačem i<br />relativne promene specifične potro&scaron;nje energije.<br />Optimalni uslovi izvođenja procesa mikrofiltracije<br />suspenzija p&scaron;eničnog skroba u uslovima<br />recirkulacije napojne suspenzije ukazuju da je<br />proces potrebno izvoditi pri maksimalnoj<br />vrednosti transmembranskog pritiska od 0,9 bara,<br />protocima od 85 do 100 L/h i koncentraciji od 5<br />do 6 g/L.<br />Optimalni uslovi izvođenja procesa mikrofiltracije<br />suspenzija p&scaron;eničnog skroba u uslovima<br />koncentrisanja napojne suspenzije ukazuju da je<br />proces potrebno izvoditi pri vrednosti<br />transmembranskog pritiska od 0,85 do 0,9 bara,<br />protocima od 85 do 100 L/h i koncentraciji od 5<br />do 7 g/L.<br />Pored ispitivanja na laboratorijskoj<br />aparaturi, cilj ovog rada je bio i ispitivanje uticaja<br />procesnih parametara na proces mikrofiltracije<br />suspenzija skroba u poluindustrijskim uslovima<br />(na jednokanalnoj i vi&scaron;ekanalnoj membrani<br />srednjeg prečnika pora 200 nm), odnosno &scaron;ireg<br />opseg vrednosti transmembranskog pritiska i<br />protoka suspenzije na pomenute odzive u<br />uslovima koncentrisanja napojne suspenzije.</p> / <p> The aim of this study was to investigate the effect of<br /> process parameters (transmembrane pressure, flow<br /> rate and suspension concentration) on the permeate<br /> flux in the system with and without the presence of<br /> static mixer. Microfiltration of wheat starch<br /> suspensions was performed in recirculation and<br /> concentration mode using ceramic membranes with<br /> different pore size (200 nm and 500 nm). Response<br /> surface methodology was applied for modeling<br /> cross-flow microfiltration of starch suspensions.<br /> During investigation of starch suspension<br /> microfiltration process on membranes with different<br /> pore size diameter (200 and 500 nm) it was<br /> observed that with increasing pore size the permeate<br /> flux declined.<br /> In the experimental range of process parameters,<br /> flux increase had values between 25% and 50% in<br /> recirculation mode, while in concentration mode<br /> this improvement was in range between 20% and 80%. The increase in flux that occurs by placing a</p> <p> static mixer in the membrane channel was caused<br /> by the establishment of turbulent flow conditions<br /> and the characteristic flow of fluid along the<br /> membrane channel, which is a consequence of the<br /> characteristic geometry of Kenics static mixer.<br /> Both in recirculation and concentration mode, the<br /> reduction of specific energy consumption depends<br /> almost exclusively on the value of the suspension<br /> flow rate. Specific energy consumption increased<br /> rapidly with increasing flow rate in the presence of<br /> static mixers and flux improvement is not high<br /> enough to compensate the loss of hydraulic<br /> dissipated power. The flow rate in the range from<br /> 80 to 100 L/h provided positive values of the<br /> reduction of specific energy consumption and the<br /> use of static mixers was justified from the<br /> economical point of view.<br /> Optimization of experimental conditions was done<br /> by a procedure of simultaneous maximization of<br /> permeate flux in systems with static mixers and<br /> reduction of specific energy consumption. Optimal<br /> conditions of the wheat starch suspension<br /> microfiltration in recirculation mode indicate that<br /> the process should be conducted at the maximum<br /> value of transmembrane pressure of 0.9 bar, flow<br /> rates from 85 to 100 L/h and concentration of 5 to 6<br /> g/L.<br /> Optimal conditions of the wheat starch suspension<br /> microfiltration in concentration mode indicate that<br /> the process should be conducted when the value of<br /> transmembrane pressure from 0.85 to 0.9 bar, flow<br /> rates from 85 to 100 L/h and concentration of 5 to 7<br /> g/L.<br /> Apart from investigations in laboratory conditions,<br /> the aim of this study was to examine the influence<br /> of process parameters on the starch suspensions<br /> microfiltration in the pilot plant (one channel and<br /> multichannel membrane with pore diameter 200<br /> nm) and wider range of transmembrane pressure<br /> and suspension flow rate on the mentioned<br /> responses in concentration mode.</p>

Modern engineering design tends to use computer simulations such as Finite Element Analysis (FEA) to replace physical experiments when evaluating a quality response, e.g., the stress level in a phone packaging process. The use of computer models has certain advantages over running physical experiments, such as being cost effective, easy to try out different design alternatives, and having greater impact on product design. However, due to the complexity of FEA codes, it could be computationally expensive to calculate the quality response function over a large number of combinations of design and environmental factors. Traditional experimental design and response surface methodology, which were developed for physical experiments with the presence of random errors, are not very effective in dealing with deterministic FEA simulation outputs. In this thesis, we will utilize a spatial statistical method (i.e., Kriging model) for analyzing deterministic computer simulation-based experiments. Subsequently, we will devise a sequential strategy, which allows us to explore the whole response surface in an efficient way. The overall number of computer experiments will be remarkably reduced compared with the traditional response surface methodology. The proposed methodology is illustrated using an electronic packaging example.

In this thesis structural optimization of castings and thermomechanical analysis of castings are studied. In paper I an optimization algorithm is created by using Matlab. The algorithm is linked to the commercial FE solver Abaqus by using Python script. The optimization algorithm uses the successive response surfaces methodology (SRSM) to create global response surfaces. It is shown that including residual stresses in structural optimization of castings yields an optimal shape that differs significantly from the one obtained when residual stresses are excluded. In paper II the optimization algorithm is expanded to using neural networks. It is tested on some typical bench mark problems and shows very promising results. Combining paper I and II the response surfaces can be either analytical functions, both linear and non-linear, or neural networks. The optimization is then performed by using sequential linear programming or by using a zero-order method called Complex. This is all gathered in a package called StuG-OPT. In paper III and IV focus is on the thermomechanical problem when residual stresses are calculated. In paper III a literature review is performed and some numerical simulations are performed to see where numerical simulations can be used in the industry today. In paper IV simulations are compared to real tests. Several stress lattices are casted and the residual stresses are measured. Simulations are performed by using Magmasoft and Abaqus. In Magmasoft a J2-plasticity model is used and in Abaqus two simulations are performed using either J2-plasticity or the ”Cast Iron Plasticity” available in Abaqus that takes into account the different behavior in tension and compression for grey cast iron. / <p>Report code: LIU-TEK-LIC-2007:34.</p>