The effect of pulsed electric fields on cell membranes were studied to investigate the effects of an electric field, per se, on biological systems, without the densometric and other technical problems associated with other forms of nonionizing radiation. Exposure of mouse splenocytes to a high voltage pulse resulted in an increase in membrane permeability to K+ that was dependent on both the electric field strength and the pulse duration. Exposure to a 2 μsec, 3.0 kV/cm pulse elicited a 50% loss of intracellular K+ indicating that the critical transmembrane potential (Vm) at breakdown was 1.26 volts for the membrane of mouse spleen cells. These results agreed with previous studies on erythrocytes and micro-organisms. Effects of a pulsed electric field on a cell's functional integrity were assessed by measuring 3H-thymidine incorporation by lymphocytes cultured in the presence and absence of various mitogens following exposure to an electrical pulse. No statistically significant effects on the response of mouse spleen lymphocytes to Con-A, PHA, or LPS were observed following exposure to a 2 usec electric pulse. Exposure to 10 μsec pulses ≥ 2.4 kV/cm produced a statistically significant reduction in the response of lymphocytes to LPS stimulation. While not statistically significant, results from both 2 and 10 usec experiments consistently indicated that exposure to pulses at sublethal electric field strengths may have a stimulatory effect on mouse spleen lymphocytes. This result is discussed and an experiment to resolve this issue is presented. Exposure of Ehrlich ascites tumor cells to 2 μsec electrical pulses produced no statistically significant alterations in the tumorigenicity of these cells. K+ release data indicated these cells are unusually resistant to the effects of pulsed electric fields having a high breakdown potential, Vm = 2.37 volts.

Poultry slaughtering encompasses a series of processing steps with the objective of harvesting the consumable meat. The scalding process consists of the submersion of carcasses in hot water tanks to facilitate the removal of feathers during slaughter. However, the use of a common scalding tank increases the likelihood of carcass cross contamination considering that dirt, fecal material and even digestive and intestinal contents carrying pathogens and other bacteria are widely spread during this operation. Similar cross contamination occurs in the process of chilling carcasses, which also requires submersion of broilers in communal tanks filled with ice and cold water. A plausible approach to reduce contamination in scalders or chillers is the use of Pulsed Electric Fields (PEF) to decontaminate scalder/ chiller water. PEF uses electricity to kill bacteria suspended in liquid media and could be utilized in poultry scalders and chillers to reduce bacterial contamination on carcasses and reduce the potential risk of pathogens reaching the final consumer. A pilot scale system was assembled by the use of a pulse electric field generator (Model SF-700, Simmons. Eng. Co., Dallas, GA) coupled with a commercial scalding tank (Dunkmaster®, Knase Company Inc, MI). C. coli and C. jejuni along with marker strains of Novobiocin and Nalidixic acid resistant S. typhimurium and S. enteritidis strains were used in challenge studies evaluating the effects of the PEF on carcasses, scalder and chiller water contamination. The system was evaluated with 0, 0.5, and 1% sodium chloride in the water with 40 volts of electric current and 0.54 of amperage. Samples were collected at 0, 40, 80, 160, 200 s of treatment with a 10 s on, 5 s off cyclical pulses. The use of PEF in regular scalder/chiller water showed little effect on Salmonella and Campylobacter reductions. However, with the addition of 0.5% NaCl caused a significant (P<0.5) log CFU/ml reduction of Salmonella and Campylobacter within the scalder/chiller water at 40, 80, and 160 seconds respectively.

High voltage treatment technology has been developed in this thesis and had initially shown promise in its effectiveness in reducing microorganisms found in water supplies. Initial testing found that the high voltage could destroy over 99.9% of the bacteria S. marcescens (a 3-log reduction). Cited literature on the effects of high voltage pulsed electric fields (PEFs) on various microorganisms have shown that high destruction rates of up to 9-log can be achieved. Thus by increasing the electric field strength or exposure time, or by improving the design of the electrode flow chamber, better results should be achieved using high voltage on water. However, contrary to this, upon further design improvements the 99.9% destruction threshold was rarely increased. The initial slow flow device of one litre-per-minute (1 LPM) was scaled up to flows of 10 LPM and 33 LPM. However, these faster flow devices were even less effective in the destruction of bacteria, destroying only 99% of S. marcescens (2-log reduction). No physical or technical design parameters could account for this low performance. One possible reason for these low results was in the preparation of the bacteria themselves. It was discovered that the growth stage of bacteria prepared for experiments had a large effect on the results. Bacteria harvested in the early growth stage could be nearly all destroyed by the high voltage (greater then 4-log reduction), whereas those harvested in the late stationary stage were much more resistant (less than 0.5-log reduction). Bacteria naturally occurring in water supplies will mostly be in a non-metabolising state. This implies that they will be more resistant to high voltage exposure than bacteria grown in a laboratory under standard testing procedures. Thus standard testing procedures for this device do not give accurate results. Further research into the mechanism behind the bacterial resistance is required to improve the performance of high voltage devices. A combination of different technologies may also prove effective in overcoming the resistance mechanism. These improvements are required before high voltage treatment can be properly developed and commercially exploited.

Living a sustainable lifestyle while facing increasing population and decreasing natural resources has become one of humanity’s largest challenges. Locating fossil fuels is becoming more difficult while the demand for them to power our societies is ever increasing. Instead of finding more efficient methods of extracting fossil fuels, developing technologies that create renewable substitutes for fossil fuels is now the strategy. Algae biofuel matches fossil fuel performance while also meeting the criteria for renewable energy. The focus now shifts to finding methods for commercially producing algae biofuel. Therefore, the objective of this thesis is to develop a system that provides the flexibility in finding the optimum operating conditions for lysing algae. Lysing is the process of disrupting the cell membrane in order to isolate the cellular components necessary to produce biofuel. The proposed system consists of cascaded power converters that provide a pulse output voltage in order to create a pulsed electric field (PEF) to lyse algae. The proposed system is unique from any known PEF systems because it provides the ability to independently adjust peak voltage, pulse width and frequency of the output voltage. This in turn provides great flexibility in determining optimum pulse voltage at various operating conditions for lysing algae. The system was tested on its ability to control the required variables while maintaining independence from the other variables. The new network was also designed and tested on how well it regulated the specific output waveform under the effects of different load currents as well as variations in the input voltage.

Cell-level and tissue-level mechanical properties are key to healthy biological functions, and many diseases and disorder arise or progress due to altered cell and tissue mechanics. Pulse electric field (PEFs), which employ intense external electric fields to cause electroporation, a phenomenon characterized by increased cell membrane permeability, also can cause significant changes to cell and tissue mechanics. Here, we investigate the mechanics of brain and brain cancer cells, specifically focusing on how PEFs impact cell mechanics and PEF-induced blood-brain barrier disruption. In our first study, we investigate single-cell mechanical disruption of glioblastoma cells after reversible electroporation using Nanonet Force Microscopy (NFM). A precise network of extracellular-matrix mimicking nanofibers enabled cell attachment and contraction, resulting in measurable fiber deflections. Cell contractile forces were shown to be temporarily disrupted after reversible electroporation, in an orientation and field-dependent manner. Furthermore, we found that cell response is often a multi-stage process involving a cell-rounding stage, biphasic stage, and a cell re-spreading stage. Additionally, cell viability post-PEFs was orientation-dependent. In another study, we investigated the mechanical properties of brain cancer for various-grade glioma cells (healthy astrocytes, grade II, grade III, and grade IV (glioblastoma) cells). A microfluidic constriction channel caused cell deformation as cells, driven by hydrostatic pressure, entered a narrow constriction. Finite element models of cell deformation and a neural network were used to convert experimental results (cell entry time and cell elongation within the channel) into elastic modulus values (kPa). We found that the that low-grade glioma cells showed higher stiffnesses compared to healthy and grade IV glioma cells, which both showed similar values. These results warrant future studies to investigate these trends further. PEFs can induce Blood-brain barrier (BBB) disruption, an effect we studied using a multiplexed, PDMS microdevice. A monolayer of human cerebral endothelial cells on a semi-permeable membrane was used to model the BBB, and permeability was assessed by the diffusion of a fluorescent dye from an upper to lower channel. A custom tapered channel and branching channel design created a linear gradient in the electric field within the device that enabled six electric field strengths to be tested at once against two unexposed (control) channels. Normalization of permeability by the control channels significantly removed experimental noise. We found that after high-frequency bipolar irreversible electroporation (HFIRE) electric pulses, permeability transiently increased within the first hour after electroporation, in a voltage- and pulse-number dependent manner. However, we found significant electrofusion events after pulsing at high voltages, which reduced monolayer permeability below baseline values. This device enables efficient exploration of a wide range of electroporation parameters to identify the optimal conditions for blood-brain barrier disruption. In another blood-brain barrier study, we incorporate dense, polystyrene nanofiber networks to create ultra-thin, ultra-porous basement-membrane-mimics for In vitro blood-brain barrier models. Fiber networks are fabricated using the non-electrospinning Spinneret-based Tunable Engineered Parameters (STEP) technique. Endothelial cells cultured on one side of the fiber network are in close contact with supporting cell types (pericytes) cultured on the backside of the fibers. Contact-orientation co-cultures have been shown to increase blood-brain barrier integrity, and our nanofiber networks increase the physiological realism of basement-membrane mimics for improve modeling. Finally, we investigate how cell viability post-electroporation is impacted by cell morphology. The impact of cell morphology (shape and cytoskeletal structure) on cell survival after electroporation is not well understood. Linking specific morphological characteristics with cell susceptibility to electroporation will enhance fundamental knowledge and will be widely useful for improving electroporation techniques where cell viability is desirable (gene transfection, electrofusion, electrochemotherapy) or where cell viability is undesirable (tumor ablation, cardiac ablation). Precise control of cell shape and orientation enabled by nanofiber scaffolds provides a convenient and expedient platform for investigating a wide variety of factors (morphological and experimental) on cell viability. Altogether, these investigations shed new light on cell mechanical changes due to disease and pulsed electric fields, and suggest opportunities for improving brain cancer therapies. / Doctor of Philosophy / In biology, structure and function are interrelated. Cells and tissue have structures that enable them to perform their proper function. In the case of disease, cell and tissue properties are altered, leading to dysfunction. Alternatively, healthy structures sometime hinder effective treatments, and therefore can be therapeutically disrupted to improve treatments. In this study, we investigate single-cell and multi-cellular mechanical change due to disease or after pulsed electric fields (PEFs), with a specific focus on the brain. Pulsed electric fields (PEFs) use electrodes to deliver short, intense pulses of electrical energy to disrupt cell membranes and change cell mechanics. We studied as single-cell contractility, cancer cell stiffness, and blood-brain barrier (BBB) disruption by PEFs. We found that PEFs cause significant change to cell shape and mechanics, and can disrupt the BBB. By studying several grades of brain cancers, we found that low-grade brain cancer (gliomas) showed increased stiffness compared to healthy and highly diseased (grade IV) cells. To mimic the BBB, we used microfluidic devices to grow specialized brain cells (endothelial cells) on permeable membranes and nanofibers networks and showed that these devices can mimic structures found in animals/humans. Finally, we studied how cell properties (such as shape) determine whether cells will survive PEFs. Taken together, our investigations improve the understanding of brain mechanics during disease and after PEFs, and suggest the usefulness of PEFs for improved brain cancer therapies.

Electroporation-based treatments are motivated by the response of biological membranes to high- intensity pulsed electric fields. These fields rearrange the membrane structure to enhance the membrane's diffusive permeability, or the degree to which a membrane allows molecules to diffuse through it, is impacted by the structure, composition, and environment in which the cell resides. Tracer molecules have been developed that are unable to pass through intact cell membranes yet enter permeabilized cells. This dissertation investigates the hypothesis that the flow of such molecules may be used to quantify the effects of the electrical stimulus and environmental conditions leading to membrane electroporation. Specifically, a series of electrical pulses that alternates between positive and negative pulses permeabilizes cells more symmetrically than a longer pulse with the same total on-time. However, the magnitude of this symmetric entry decreases for the shorter alternating pulses. Furthermore, a method for quantitatively measuring the permeability of the cell membrane was proposed and validated. From data near the electroporation threshold, the response of cells varies widely in the manner in which cells become permeabilized. This method is applied to study the transient cell membrane permeability induced by electroporation and is used to demonstrate that the cell membrane remains permeable beyond 30 min following treatment. To analyze these experimental findings in the context of physical mechanisms, computational models of molecular uptake were developed to simulate electroporation. The results of these simulations indicate that the cell's local environment during electroporation facilitates the degree of molecular uptake. We use these models to predict how manipulating both the environment of cells during electroporation affects the induced membrane permeability. These experimental and computational results provide evidence that supports the hypothesis of this dissertation and provide a foundation for future investigation and simulation of membrane electroporation. / PHD / Electroporation is a biophysical process in which intense electric fields permeabilize bilayer membranes. The degree to which a membrane allows molecules to diffuse through it is called its diffusive permeability, and is impacted by the structure, composition, and environment in which the cell resides. This dissertation investigates the hypothesis that the flow of molecules into cells through their membranes may be used to quantitatively study the effects of the electrical stimulus and environmental conditions leading to membrane disruption. Here, I demonstrate that the cellular response to pulsed electric fields is affected by the waveform of the applied electrical stimulus. Specifically, a series of electrical pulses that alternates between positive and negative pulses permeabilizes cells more symmetrically than a longer pulse with the same total energized time. However, the total molecular uptake decreases for the shorter alternating pulses over the longer pulse. A method for quantitatively measuring the permeability of the cell membrane using a fluorescent tracer molecule is also developed and validated. This method is applied to show how cell membrane permeability changes following electroporation. To analyze these findings, computational models of molecular flow through the cell membrane are developed. These simulations indicate that the cell’s surrounding environment during electroporation dramatically impacts the degree of molecular uptake. We use these models to predict how manipulating both the environment of cells during electroporation affects the induced membrane permeability. These experimental and computational results provide a foundation for future investigation and simulation of membrane electroporation.

Le procédé industriel d’extraction d'inuline consiste en une diffusion de longue durée et à température élevée. Ce procédé induit l’extraction des sucres mais également des impuretés. Les étapes de purification de jus deviennent alors plus complexes. Pour pallier à ces problèmes, il est essentiel de réduire la température de diffusion pour limiter l’extraction des impuretés. Récemment, la technique de champs électriques pulsés (CEP) a démonté ses avantages dans le domaine sucrier et également dans d’autres applications agro-alimentaires. L’objectif de ce travail de thèse est de d’optimiser et valider la faisabilité de cette techniques dans le cas de la chicorée. Une purification par filtration dynamique est envisagée et proposée pour remplacer la purification classique. Les résultats de l’extraction montrent qu’il est possible d’intensifier l’extraction de l’inuline par application de CEP. Le prétraitement des cossettes de chicorées à 600 V/cm et 50 ms, réduit de 20°C la température de diffusion (60°C au lieu de 80°C actuellement). Une économie d’énergie importante est réalisée (gain 90 kJ/kg chicory juice). La combinaison innovante d’un prétraitement électrique et un traitement thermique (chauffage ohmique) provoque une perméabilisation importante des cellules et permet de réaliser des diffusions « à froid ». Les analyses qualitatives de jus de diffusion classique et jus CEP montrent que la pureté des extraits CEP est plus élevée (87.2% vs 86.7%). Les essais de filtration sur membrane montrent que les performances de la filtration (pureté, flux, colmatage,…) dépendent énormément de l’origine de l’extrait. Le jus CEP contient moins d’impureté que le jus thermique, est donc plus facile à filtré. Cependant, col matage de membrane restent dans les deux cas important. Un module de filtration dynamique avec disque rotatif a été utilisé pour améliorer les performances de la filtration. Ce module a permit de réduire le colmatage des membranes, améliorer la pureté des extraits et atteindre des facteurs de réduction volumique important (10). / Industrial inulin extraction requires high temperature and long duration to ensure inulin productivity. In addition complex steps are necessary to purify extracted chicory juice and to obtain inulin with desirable purity. In order to avoid the extracting of inulin at high temperature, to obtain chicory juice with better quality and to purify chicory juice with more simple operation, pulsed electric fields (PEF) and membrane filtration were applied to this study : PEF was used to intensify inulin extraction from chicory roots. By pre-treatment of chicory slices at 600 V/cm, diffusion temperature at pilot scale can be decreased to 60oC from about 80oC (industrial extraction condition) to obtain comparable juice inulin concentration. Moreover, this moderate temperature diffusion brought out interesting energy savings compared to that of conventional diffusion. For the goal of extracting inulin at “cold” condition (for example 30oC) PEF induced combined electroporation/ohmic heating pretreatment was applied for chicory tissue denaturation. Better solute extraction was observed after effective damage of chicory tissue diffusivity.Juice extracted from PEF assisted diffusion (PEF juice) was confirmed had higher inulin purity and less impurity in comparison to juice from conventional thermal diffusion process. The juice was purified by membrane filtration in order to investigate a simple chicory juice purification method. Since it contains less impurity, dead-end filtration performance of PEF juice was significantly improved, with less membrane fouling and higher inulin purity in filtrate. However, permeate flux of membrane filtration was seriously restricted by the membrane fouling. In order to improve filtration flux, rotating disk module was introduced in this study for clarification and purification of chicory juice. Elevated shear rate of rotating disk (1500–2000 rpm) could effectively control or even eliminate membrane fouling and lead to satisfying carbohydrate transmission (98%) and desirable permeate flux even at high volume reduction ratio (10). In view of energy saving, optimization of RDM assisted chicory juice filtration was carried out and yielded optimal operation conditions to maximize average flux and minimize specific energy consumption.

O presente trabalho teve como objetivo estudar diferentes tecnologias na extração de óleo da semente de gergelim e de compostos fenólicos e proteínas da torta de gergelim. Este estudo está dividido em quatro partes. O objetivo da primeira parte do trabalho foi extrair compostos fenólicos de diferentes tortas de nozes e sementes nas mesmas condições e comparar o teor de tais compostos e a atividade antioxidante dos extratos. Nessa fase, foram utilizadas nos experimentos tortas das sementes de girassol, linhaça e gergelim, e das nozes amêndoa, pecã, macadâmia e avelã. O extrato da torta de noz pecã apresentou o maior teor de todos os compostos fenólicos analisados, seguido pelo extrato da torta de semente de girassol e de avelã. Essas amostras também apresentaram as maiores atividades antioxidantes. As etapas seguintes do trabalho focaram-se no gergelim. A segunda parte do trabalho teve como objetivo a otimização da extração, pela metodologia convencional, de fenólicos totais e lignanas da torta de gergelim. Inicialmente, um modelo polinomial de segunda ordem foi utilizado para predição dos resultados, mediante a variação da temperatura, concentração de etanol e razão, sólido/solvente. As variáveis de resposta foram as concentrações de fenólicos totais, de sesamina e de sesaminol triglicosídeo e a atividade antioxidante dos extratos obtidos. Entre os compostos analisados, o sesaminol triglicosídeo está presente em maior quantidade na torta de gergelim. A razão sólido/solvente e a concentração de etanol foram os fatores que mais afetaram a extração, enquanto a temperatura demonstrou uma influência reduzida. Na terceira etapa, o escopo da pesquisa foi a avaliação de metodologias alternativas na extração desses mesmos compostos e, também, de proteínas. As tecnologias usadas foram as de campo elétrico pulsado (CEP) e de descargas elétricas de alta tensão (DEAT). A análise da aplicação de CEP e de DEAT foi realizada usando essas tecnologias como pré-tratamentos ao processo de extração com solvente. Os resultados demonstraram que as técnicas foram eficazes e aumentaram os rendimentos do processo para fenólicos totais, lignanas e proteínas da torta. O uso de diferentes porcentagens de etanol também se mostrou significativo nessa etapa, entretanto, esse efeito foi reduzido quando utilizadas as tecnologias elétricas. Da mesma forma, o efeito da temperatura na etapa difusiva foi menor quando os pré-tratamento foram utilizados. Os comportamentos observados sugerem que a aplicação de CEP e DEAT aumenta a eficiência da extração de compostos de interesse. Por fim, na quarta parte do trabalho, objetivou-se melhorar a eficiência do processo de extração do óleo de gergelim aplicando as tecnologias previamente citadas. Esses experimentos demonstraram um efeito significativo dos tratamentos de CEP e DEAT e um aumento na quantidade de óleo extraído com o aumento da energia aplicada às sementes. O uso de DEAT gerou um aumento maior na quantidade de óleo extraído, se comparado à tecnologia de CEP. / The goal of the present work was to study different technologies in the extraction of oil from sesame seed and phenolic compounds and proteins from sesame cake. This study is divided in four parts. The first part aimed to extract water-soluble compounds from different seed and nut cakes under the same conditions and compare the phenolic content and antioxidant activity of the extracts. For the first portion of the study, seed cakes of sunflower, pumpkin, flaxseed and defatted sesame, and nut cakes of almond, pecan, macadamia and hazelnut were used in the experiments. The extract from pecan nut cake presented the highest amounts of all compounds analyzed, followed by sunflower seed and hazelnut cake extracts. These samples also had the highest antioxidant activities. The following steps of the work focused on sesame only. The second part of the work aimed to optimize the extraction of total phenolics and lignans from sesame seed cake. Initially, a second-order polynomial model was set up to predict the responses in different temperatures, solid/solvent ratios and ethanol concentrations. The response variables were the concentrations of total phenolics, sesamin, sesaminol triglucoside and antioxidant activity of the extracts. Among the analyzed compounds, ST is presented in the highest quantity in sesame cake. Solid to liquid ratio and ethanol concentration where the most important factors affecting extraction, whereas temperature showed reduced influence. In the third part of this work, the aim was to evaluate alternative methodologies in the extraction of phenolics and proteins. The technologies used were pulsed electric fields (PEF) and high voltage electric discharges (HVED). These methods were used as pre-treatments, prior to diffusion. Result show that PEF and HVED were efficient and increased the extraction yield for phenolic compounds, lignans and proteins from the cake. The use of different percentages of ethanol was also significant in this stage; however, the effect of this parameter was reduced when the electrical treatments were used. In the same way, temperature also showed a smaller influence on the results when the pre-treatments were used. The observed behaviors suggest that the use of PEF and HVED increases extraction efficiency. Finally, the goal of the last part of the work was to improve oil expression from sesame seeds, using the aforementioned technologies. These experiments show a significant effect of both PEF and HVED. It was observed an increase of the amount of oil extracted with the energy input applied to the seeds. When compared both technologies, HVED showed a more expressive effect then PEF.

O presente trabalho teve como objetivo estudar diferentes tecnologias na extração de óleo da semente de gergelim e de compostos fenólicos e proteínas da torta de gergelim. Este estudo está dividido em quatro partes. O objetivo da primeira parte do trabalho foi extrair compostos fenólicos de diferentes tortas de nozes e sementes nas mesmas condições e comparar o teor de tais compostos e a atividade antioxidante dos extratos. Nessa fase, foram utilizadas nos experimentos tortas das sementes de girassol, linhaça e gergelim, e das nozes amêndoa, pecã, macadâmia e avelã. O extrato da torta de noz pecã apresentou o maior teor de todos os compostos fenólicos analisados, seguido pelo extrato da torta de semente de girassol e de avelã. Essas amostras também apresentaram as maiores atividades antioxidantes. As etapas seguintes do trabalho focaram-se no gergelim. A segunda parte do trabalho teve como objetivo a otimização da extração, pela metodologia convencional, de fenólicos totais e lignanas da torta de gergelim. Inicialmente, um modelo polinomial de segunda ordem foi utilizado para predição dos resultados, mediante a variação da temperatura, concentração de etanol e razão, sólido/solvente. As variáveis de resposta foram as concentrações de fenólicos totais, de sesamina e de sesaminol triglicosídeo e a atividade antioxidante dos extratos obtidos. Entre os compostos analisados, o sesaminol triglicosídeo está presente em maior quantidade na torta de gergelim. A razão sólido/solvente e a concentração de etanol foram os fatores que mais afetaram a extração, enquanto a temperatura demonstrou uma influência reduzida. Na terceira etapa, o escopo da pesquisa foi a avaliação de metodologias alternativas na extração desses mesmos compostos e, também, de proteínas. As tecnologias usadas foram as de campo elétrico pulsado (CEP) e de descargas elétricas de alta tensão (DEAT). A análise da aplicação de CEP e de DEAT foi realizada usando essas tecnologias como pré-tratamentos ao processo de extração com solvente. Os resultados demonstraram que as técnicas foram eficazes e aumentaram os rendimentos do processo para fenólicos totais, lignanas e proteínas da torta. O uso de diferentes porcentagens de etanol também se mostrou significativo nessa etapa, entretanto, esse efeito foi reduzido quando utilizadas as tecnologias elétricas. Da mesma forma, o efeito da temperatura na etapa difusiva foi menor quando os pré-tratamento foram utilizados. Os comportamentos observados sugerem que a aplicação de CEP e DEAT aumenta a eficiência da extração de compostos de interesse. Por fim, na quarta parte do trabalho, objetivou-se melhorar a eficiência do processo de extração do óleo de gergelim aplicando as tecnologias previamente citadas. Esses experimentos demonstraram um efeito significativo dos tratamentos de CEP e DEAT e um aumento na quantidade de óleo extraído com o aumento da energia aplicada às sementes. O uso de DEAT gerou um aumento maior na quantidade de óleo extraído, se comparado à tecnologia de CEP. / The goal of the present work was to study different technologies in the extraction of oil from sesame seed and phenolic compounds and proteins from sesame cake. This study is divided in four parts. The first part aimed to extract water-soluble compounds from different seed and nut cakes under the same conditions and compare the phenolic content and antioxidant activity of the extracts. For the first portion of the study, seed cakes of sunflower, pumpkin, flaxseed and defatted sesame, and nut cakes of almond, pecan, macadamia and hazelnut were used in the experiments. The extract from pecan nut cake presented the highest amounts of all compounds analyzed, followed by sunflower seed and hazelnut cake extracts. These samples also had the highest antioxidant activities. The following steps of the work focused on sesame only. The second part of the work aimed to optimize the extraction of total phenolics and lignans from sesame seed cake. Initially, a second-order polynomial model was set up to predict the responses in different temperatures, solid/solvent ratios and ethanol concentrations. The response variables were the concentrations of total phenolics, sesamin, sesaminol triglucoside and antioxidant activity of the extracts. Among the analyzed compounds, ST is presented in the highest quantity in sesame cake. Solid to liquid ratio and ethanol concentration where the most important factors affecting extraction, whereas temperature showed reduced influence. In the third part of this work, the aim was to evaluate alternative methodologies in the extraction of phenolics and proteins. The technologies used were pulsed electric fields (PEF) and high voltage electric discharges (HVED). These methods were used as pre-treatments, prior to diffusion. Result show that PEF and HVED were efficient and increased the extraction yield for phenolic compounds, lignans and proteins from the cake. The use of different percentages of ethanol was also significant in this stage; however, the effect of this parameter was reduced when the electrical treatments were used. In the same way, temperature also showed a smaller influence on the results when the pre-treatments were used. The observed behaviors suggest that the use of PEF and HVED increases extraction efficiency. Finally, the goal of the last part of the work was to improve oil expression from sesame seeds, using the aforementioned technologies. These experiments show a significant effect of both PEF and HVED. It was observed an increase of the amount of oil extracted with the energy input applied to the seeds. When compared both technologies, HVED showed a more expressive effect then PEF.

O presente trabalho teve como objetivo estudar diferentes tecnologias na extração de óleo da semente de gergelim e de compostos fenólicos e proteínas da torta de gergelim. Este estudo está dividido em quatro partes. O objetivo da primeira parte do trabalho foi extrair compostos fenólicos de diferentes tortas de nozes e sementes nas mesmas condições e comparar o teor de tais compostos e a atividade antioxidante dos extratos. Nessa fase, foram utilizadas nos experimentos tortas das sementes de girassol, linhaça e gergelim, e das nozes amêndoa, pecã, macadâmia e avelã. O extrato da torta de noz pecã apresentou o maior teor de todos os compostos fenólicos analisados, seguido pelo extrato da torta de semente de girassol e de avelã. Essas amostras também apresentaram as maiores atividades antioxidantes. As etapas seguintes do trabalho focaram-se no gergelim. A segunda parte do trabalho teve como objetivo a otimização da extração, pela metodologia convencional, de fenólicos totais e lignanas da torta de gergelim. Inicialmente, um modelo polinomial de segunda ordem foi utilizado para predição dos resultados, mediante a variação da temperatura, concentração de etanol e razão, sólido/solvente. As variáveis de resposta foram as concentrações de fenólicos totais, de sesamina e de sesaminol triglicosídeo e a atividade antioxidante dos extratos obtidos. Entre os compostos analisados, o sesaminol triglicosídeo está presente em maior quantidade na torta de gergelim. A razão sólido/solvente e a concentração de etanol foram os fatores que mais afetaram a extração, enquanto a temperatura demonstrou uma influência reduzida. Na terceira etapa, o escopo da pesquisa foi a avaliação de metodologias alternativas na extração desses mesmos compostos e, também, de proteínas. As tecnologias usadas foram as de campo elétrico pulsado (CEP) e de descargas elétricas de alta tensão (DEAT). A análise da aplicação de CEP e de DEAT foi realizada usando essas tecnologias como pré-tratamentos ao processo de extração com solvente. Os resultados demonstraram que as técnicas foram eficazes e aumentaram os rendimentos do processo para fenólicos totais, lignanas e proteínas da torta. O uso de diferentes porcentagens de etanol também se mostrou significativo nessa etapa, entretanto, esse efeito foi reduzido quando utilizadas as tecnologias elétricas. Da mesma forma, o efeito da temperatura na etapa difusiva foi menor quando os pré-tratamento foram utilizados. Os comportamentos observados sugerem que a aplicação de CEP e DEAT aumenta a eficiência da extração de compostos de interesse. Por fim, na quarta parte do trabalho, objetivou-se melhorar a eficiência do processo de extração do óleo de gergelim aplicando as tecnologias previamente citadas. Esses experimentos demonstraram um efeito significativo dos tratamentos de CEP e DEAT e um aumento na quantidade de óleo extraído com o aumento da energia aplicada às sementes. O uso de DEAT gerou um aumento maior na quantidade de óleo extraído, se comparado à tecnologia de CEP. / The goal of the present work was to study different technologies in the extraction of oil from sesame seed and phenolic compounds and proteins from sesame cake. This study is divided in four parts. The first part aimed to extract water-soluble compounds from different seed and nut cakes under the same conditions and compare the phenolic content and antioxidant activity of the extracts. For the first portion of the study, seed cakes of sunflower, pumpkin, flaxseed and defatted sesame, and nut cakes of almond, pecan, macadamia and hazelnut were used in the experiments. The extract from pecan nut cake presented the highest amounts of all compounds analyzed, followed by sunflower seed and hazelnut cake extracts. These samples also had the highest antioxidant activities. The following steps of the work focused on sesame only. The second part of the work aimed to optimize the extraction of total phenolics and lignans from sesame seed cake. Initially, a second-order polynomial model was set up to predict the responses in different temperatures, solid/solvent ratios and ethanol concentrations. The response variables were the concentrations of total phenolics, sesamin, sesaminol triglucoside and antioxidant activity of the extracts. Among the analyzed compounds, ST is presented in the highest quantity in sesame cake. Solid to liquid ratio and ethanol concentration where the most important factors affecting extraction, whereas temperature showed reduced influence. In the third part of this work, the aim was to evaluate alternative methodologies in the extraction of phenolics and proteins. The technologies used were pulsed electric fields (PEF) and high voltage electric discharges (HVED). These methods were used as pre-treatments, prior to diffusion. Result show that PEF and HVED were efficient and increased the extraction yield for phenolic compounds, lignans and proteins from the cake. The use of different percentages of ethanol was also significant in this stage; however, the effect of this parameter was reduced when the electrical treatments were used. In the same way, temperature also showed a smaller influence on the results when the pre-treatments were used. The observed behaviors suggest that the use of PEF and HVED increases extraction efficiency. Finally, the goal of the last part of the work was to improve oil expression from sesame seeds, using the aforementioned technologies. These experiments show a significant effect of both PEF and HVED. It was observed an increase of the amount of oil extracted with the energy input applied to the seeds. When compared both technologies, HVED showed a more expressive effect then PEF.