O charque é um produto cárneo tipicamente brasileiro, salgado e seco ao sol, ainda produzido de maneira artesanal. Durante sua produção há uma etapa de fermentação, realizada pela microbiota naturalmente presente na matéria-prima, o que dificulta a padronização do produto, e pode influenciar negativamente em suas características sensoriais e qualidade microbiológica. O controle da etapa de fermentação do charque seria uma alternativa para minimizar este problema e, neste contexto, as bactérias láticas produtoras de bacteriocinas se enquadram de forma interessante. A microbiota autóctone de charque inclui principalmente bactérias láticas e micro-organismos halofílicos e halotolerantes, sendo assim, este produto apresenta potencial como fonte para o isolamento de novas bactérias láticas produtoras de bacteriocinas. Assim, este trabalho teve por objetivo isolar e identificar culturas de bactérias láticas produtoras de bacteriocinas naturalmente presentes no charque, caracterizar parcialmente as bacteriocinas produzidas por essas culturas, avaliar seu potencial de aplicação neste produto para a melhoria de sua qualidade microbiológica e avaliar seu efeito na ecologia microbiana do charque, nas diferentes etapas de sua fabricação. Através da técnica de tripla camada em ágar foi isolada uma cepa de Lactococcus lactis subsp. lactis apresentando o gene codificador para nisina Z e com capacidade de inibir, in vitro, micro-organismos medianamente e altamente halotolerantes isolados de charque, além de outros micro-organismos deteriorantes e patogênicos importantes em alimentos, como Lactobacillus spp., Listeria monocytogenes e Staphylococcus aureus. A bacteriocina produzida pela cepa isolada neste estudo também possui características interessantes para sua aplicação na bioconservação de alimentos, como resistencia ao calor, presença de agente químicos e altos teores de NaCl, além de não ser afetada pelo pH. A aplicação dessa cepa em charque modelo resultou na redução de até 2 ciclos log na população de micro-organismos halotolerantes, indicando apresentar um potencial de aplicação como agente de bioconservação do produto. Os ensaios de avaliação da ecologia microbiana, empregando DGGE, indicaram que a fermentação natural do charque ocorreu com a participação de bactérias láticas dos gêneros Lactobacillus, Streptococcus, Lactococcus e de micro-organismos halotolerantes do gênero Staphylococcus. Além disso, os estudos referentes à dinâmica populacional demonstraram que a adição da cepa bacteriocinogênica ao charque não influenciou, de forma qualitativa, as populações presentes no produto. / Charqui is a Brazilian traditional meat product, salted and sun-dried, still manufactured without control of the fermentation step, which is performed by the indigenous microbiota. This fact interferes on the standardization of the product and can negatively affect the sensorial properties and microbiological quality. The application of a known microbiota would be an alternative to minimize this problem and the bacteriocin-producing lactic acid bacteria can can fit in this purpose. The charqui indigenous microbiota mainly includes lactic acid bactéria and halophilic and halotolerant microorganisms, therefore, this product presents a potencial as a source for the isolation of new bacteriocin-producing lactic acid bacteria. The aim of the present work was to isolate and identify bacteriocin-producing lactic acid bacteria from charqui, characterize the bacteriocins produced by the isolated culture, evaluate its potential as biopreservative in charqui and its influence on the microbial populations during the manufacture of the product. A bacteriocinogenic Lactococcus lactis subsp. lactis strain was isolated from charqui through the triple-layer agar technique. This strain produces a nisin-like bacteriocin capable to inhibit in vitro medium and highly halotolerant bacteria isolated from charqui and other food-borne pathogenic and spoilage microorganisms. The application of this strain for charqui manufacturing caused a reduction of up to 2 log in the halotolerant bacteria population, evidencing its potential application for charqui biopreservation. Studies in the populational dynamics using DGGE indicated that the presence of the bacteriocinogenic strain did not affect the microbial populations in the product.

Cette thèse porte sur la production d'acide lactique par conversion de la biomasse lignocellulosique catalysée par des acides de Lewis solides dans l'eau puis l'estérification d'acide lactique aqueux avec de l'éthanol. La conversion de la cellulose est étudiée en autoclave, en utilisant comme catalyseurs, de la zircone et de l'alumine contenant du W ou Sn (ZrW, AlSn) et différents hydroxydes métalliques. L'étude de la conversion de la cellulose en acide lactique en présence de ZrW non calcinée, ZrW calcinée, Zr(OH)4 et ZrO2, montre que la phase active du catalyseur est constituée de Zr4+, les centres acides de Lewis et de groupes hydroxyles. Les performances catalytiques des catalyseurs AlSn, préparés à partir de chlorure d'étain comme précurseur, dépendent fortement de la présence résiduelle de chlorure, ce qui favorise la formation d'acide lévulinique. Les hydroxydes de certains métaux de transition se sont révélés être des catalyseurs solides efficaces pour la conversion de la cellulose en acide lactique. Il a été observé que le rendement en acide lactique dépend de la concentration et de la basicité des groupes OH superficiels des hydroxydes de métaux de transition et de la présence de sites acides de Lewis. L'estérification de l'acide lactique, à différentes concentrations en l'eau, a été étudiée en présence d'Amberlyst 15, de charbon sulfoné et d'oxyde de graphène pour étudier l'activité et la tolérance à l'eau de catalyseurs solides acides à base de carbone. Il est montré, par calorimétrie d'adsorption d'ammoniac, que l'oxyde de graphène présente des sites superacides et qu'il conduit à la plus grande activité et tolérance à l'eau. L'augmentation de la teneur en eau montre un fort effet inhibiteur sur l'activité du charbon sulfoné alors que d'Amberlyst 15 et l'oxyde de graphène sont plus tolérants. Les catalyseurs ne sont pas stables dans des conditions d'estérification, en présence d'eau / This thesis reports the synthesis of lactic acid from lignocellulosic biomass catalyzed by solid Lewis acid catalysts in water and then esterification of aqueous lactic acid solutions with ethanol. The cellulose conversion was tested in autoclave, in hot water, using zirconia and alumina containing W or Sn (ZrW, AlSn) and different solid metal hydroxides. The conversion of cellulose to lactic acid using uncalcined ZrW, calcined ZrW, Zr(OH)4 and ZrO2 shows that the active surface of the catalyst consists of Zr4+ Lewis centers and OH groups. The catalytic performances of AlSn catalysts, prepared from Sn chloride as precursors, strongly depend on the residual amount of chloride which favors the formation of levulinic acid. Some hydroxides of transition metals were disclosed as efficient solid catalysts for the conversion of cellulose to lactic acid. The yield of lactic acid was observed to depend on the concentration and the basicity of the superficial OH groups and on the presence of Lewis acid sites. The esterification of lactic acid, at different concentrations in water, was studied using Amberlyst 15, sulfonated carbon and graphene oxide to evaluate the activities and water tolerance of carbon based solid catalysts. Graphene oxide, shown by calorimetry of NH3 adsorption to exhibit super-acid sites, leads the highest activity and water tolerance. Increasing amounts of water has a strong inhibiting effect on the activity of sulfonated carbon and less influence on activity of Amberlyst 15 and graphene oxide. However, all catalysts were not stable in esterification conditions, in presence of water

Le poly(acide lactique), PLA, est un polymère biocompatible et biodégradable, qui peut être produit à partir de ressources renouvelables. En conséquence, il a soulevé une attention toute particulière en tant que remplacement éventuel des polymères à base de pétrole. C’est un polyester aliphatique ayant des propriétés telles que module élevé, haute résistance, biocompatibilité et est donc un matériau prometteur pour diverses applications telles que les implants, l’encapsulation de médicaments et l'emballage. A cause de sa faible température de transition vitreuse, le PLA a une faible résistance thermique et les applications sont donc limitées à celles qui ne sont pas associées à des températures élevées. En outre, ce polymère souffre d'un faible degré de cristallinité. L'augmentation du taux de cristallinité dans de nombreuses techniques de mise en forme, telles que le moulage par injection, est nécessaire. Il y a plusieurs façons d'augmenter le niveau de cristallinité du PLA. Ces procédés comprennent l'utilisation d'agents nucléants, de plastifiants, ou de combinaisons d'agents plastifiants et de nucléation. La cristallisation du PLA à l'état fondu se présente sous deux formes cristallines légèrement différentes connues sous les noms α et α'. Cette étude compare la capacité d'auto-nucléation de ces deux formes cristallines par auto-nucléation. Ceci est réalisé en comparant les températures de cristallisation lors du refroidissement des échantillons préalablement cristallisés à diverses températures, puis de nouveau chauffé à une température dans la plage de fusion partielle du PLA. Dans la deuxième étape, l'effet des paramètres cinétiques et le poids moléculaire du PLA sur l'efficacité de nucléation des PLA phases cristallines a été étudié. Cette partie de l’étude ouvre une nouvelle voie pour comprendre le rôle des modifications cristallines du PLA qui mènent aux conditions optimales pour la cristallisation du PLA. La mise en forme des polymères implique des contraintes de cisaillement et d’élongation, ce qui implique une cristallisation induite par l’écoulement et la solidification qui s’en suit. Les propriétés mécaniques des produits finals dépendent du degré de cristallisation et de la nature des cristaux formés. Par conséquent, l'optimisation du procédé nécessite une bonne compréhension de la façon dont l’écoulement influence la cristallisation. Le type d'écoulement peut jouer un rôle important sur la cristallisation. Par exemple, l'écoulement élongationnel provoque l’orientation et l’étirement des molécules dans le sens de l'extension, comme dans le cas de la mise en forme de fibres et le soufflage de film, en aidant le processus de cristallisation induite par l'écoulement. Une littérature abondante existe sur la ii cristallisation des thermoplastiques classiques induite par l'écoulement. Cela dit, moins d'attention a été accordée à l'effet de l'écoulement de cisaillement et d'allongement sur la cristallisation du PLA. Comme étudié dans la dernière partie de ce document, l'effet du poids moléculaire sur la cristallisation induite par cisaillement du PLA est rapporté. Pour cela, trois différents PLA à faible, moyen et haut poids moléculaire ont été préparés par réaction d'hydrolyse. Ensuite, en utilisant un rhéomètre oscillatoire, l’effet du cisaillement sur la cinétique de cristallisation du PLA a été examiné. / Abstract : Poly(lactic acid), PLA, is a biocompatible and biodegradable polymer that can be produced from renewable resources. As a result, it has raised particular attention as a potential replacement for petroleum-based polymers. It is an aliphatic polyester with properties such as high modulus, high strength, and biocompatibility and is thus a promising material for various applications such as implants, drug encapsulation, and packaging. In the wake of low glass transition temperature, PLA has a low heat resistance and its application is limited to those not associated with high temperatures. In addition, this polymer suffers from a low degree of crystalinity. Increasing the crystallization rate in many processing operations, such as injection molding, is required. So far, many routes have been found to improve the crystallinity of PLA. These methods include using nucleating agents, plasticizers, and combination of nucleating agents and plasticizers together. PLA crystallization in the melt state results in two slightly different crystalline forms known as α and α’forms. This thesis compares the self-nucleation ability of these two crystal forms by self-nucleation. This is achieved by comparing crystallization temperatures upon cooling for samples previously crystallized at various temperatures and then re-heated to a temperature in the partial melting range for PLA. In the second step, we study the effect of molecular weight of PLA on the nucleation efficiency of PLA crystalline phases. This part of the investigation opens a new pathway to understand the role of PLA crystalline phases on the optimal condition for its crystallization kinetics. Polymer processing operations involve mixed shear and elongational flows and cause polymer molecules to experience flow-induced crystallization during flow and subsequent solidification. The mechanical properties of the final products are significantly dependent upon the degree of crystallization and types of formed crystals. Therefore, optimization of any polymer process requires a good understanding of how flow influences crystallization. The type of flow can play a significant role in affecting crystallization. For example, elongational flow causes molecules to orient and stretch in the direction of extension, as in the case of fiber spinning and film blowing, helping the process of flow-induced crystallization. An extensive body of literature exists on flow-induced crystallization of conventional thermoplastics. Having said that, less attention has been paid to the effect of shear and elongational flow on the PLA crystallization kinetics. As investigated in the final part of this thesis, the effect of iv molecular weight on the shear-induced crystallization of PLA is reported. For this, low, medium and high molecular-weight PLAs were prepared from a high molecular weight one by a hydrolysis reaction. Next, by means of a simple rotational rheometry, effect of the shear flow was examined on the crystallization kinetics of these three PLAs.

Cette thèse de doctorat porte sur la valorisation du déchet solide issu de la préparation de la mélasse de caroube libanaise pour la production de bioénergie et de molécules à valeur ajoutée. L’analyse de la composition de ce déchet a montré qu’il contient 45 % (g/g) de sucres, substrats exploitables pour la fermentation alcoolique ou lactique, la production de biohydrogène, ou comme source de carbone pour la croissance d’une algue dans un procédé de phycoremédiation (traitement des eaux par les algues) pour l’élimination de micropolluants pharmaceutiques. Les résultats obtenus ont montré que la fermentation alcoolique en phase liquide à partir d’extraits de déchet de caroube peut conduire à des rendements élevés en bioéthanol sous réserve d’enrichir le milieu de culture par les éléments nécessaires pour la croissance de la levure Saccharomyces cerevisiae (en particulier l’azote), tandis qu’il est possible de produire directement le bioéthanol sur le déchet par fermentation en milieu solide sous réserve de contrôler précisément l’humidité. Nous avons également démontré que la fermentation lactique par immobilisation de Lactobacillus rhamnosus sur des billes d’alginate constitue une alternative possible au bioéthanol pour les sucres extraits du déchet. Cependant, un enrichissement du milieu de culture, ainsi que l’utilisation d’une invertase en prétraitement sont nécessaires afin de maximiser le rendement et la productivité de l’acide lactique. L’immobilisation des microorganismes a permis de réutiliser les mêmes billes d’alginate au cours de cinq cycles successifs de production. Une autre alternative potentielle aux voies précédentes est la fermentation sombre pour la production de biohydrogène directement à partir du déchet. Si des rendements intéressants ont été atteints, il faut noter que comme précédemment dans le cas de la fermentation solide du déchet, une forte dépendance aux conditions initiales de broyage a été mise en évidence ; de plus, à la carence en azote qui obligeait à supplémenter les milieux en fermentation en phase liquide s’ajoutent des besoins en fer. Enfin, l’utilisation du déchet comme substrat carboné dans un procédé de phycoremédiation avec l’algue Ankistrodesmus braunii a montré que l’élimination de 90% du diclofénac initial pouvait être atteinte en conditions de mixotrophie, même si seulement un tiers du diclofénac éliminé est effectivement métabolisé par l’algue. / This PhD thesis deals with the valorization of the solid waste generated by the Lebanese carob molasse process with the aim to produce bioenergy or high added-value platform molecules. The chemical analysis of this waste has highlighted that it contains 45% (w/w) sugars, which can be used as a substrate for alcoholic or lactic fermentation, the production of biohydrogen by dark fermentation, or as a carbon source for the growth of microalgae in a phycoremediation process (water treatment process based on algae/microalgae) for the removal of pharmaceutical micropollutants. Experimental results have shown that high ethanol yield and productivity could be achieved through alcoholic fermentation in the liquid phase using extracts from carob waste as the substrate, provided the culture medium was enriched by complementary nutrients (especially a nitro-gen source) to enhance the growth of the yeast Saccharomyces cerevisiae; in parallel, the direct production of ethanol from the solid waste based on solid-state fermentation was also proved to be efficient, provided humidity was accurately controlled. In addition, lactic fermentation per-formed with immobilized Lactobacillus rhamnosus on alginate beads was shown to constitute a potential alternative to bioethanol for the extracts from carob waste. An enriched culture medium was, however, necessary, together with the use of an invertase enzyme as a pretreatment so as to maximize the yield and the productivity of lactic acid. Using microorganism immobilization lead to the opportunity to recycle at least five times alginate beads in successive culture cycles. Another potential alternative to the above-mentioned valorization pathways was proved to lie in the dark fermentation process for biohydrogen production, directly using the solid waste. While attractive yields were reached, a strong dependence on the particle size from grinding pretreatment was emphasized, as in solid-state fermentation; moreover, iron supplementation in the culture medium was compulsory, in addition to nitrogen supplementation already described when fermentation was carried out in the liquid phase. Finally, when the carob waste was used as a substrate for the growth of the algae Ankistrodesmus braunii in a phycoremediation process, a removal yield of the initial diclofenac content about 90% could be reached under mixotrophic conditions, even though only one third of the diclofenac removed was effectively metabolized.

Among the wide range of products naturally fermented by lactic acid bacteria (LAB), there are the homemade cheeses. These bacteria are inherent to the raw milk and the fermentation process for producing compounds responsible for the flavor and texture of the products. Its use is one of the oldest food preservation techniques, since they are able to produce substances with antagonistic action against spoilage and pathogenic microorganisms, particularly Listeria monocytogenes, commonly found in refrigerated dairy products. In addition, many lactic acid bacteria have probiotic potential, thus becoming the most attractive one for its use. In North West Frontier region of Rio Grande do Sul a typical cheese is produced, popularly called colonial cheese, which its knowledge of fabrication techniques have been transferred verbally through generations. For being manufactured, in most cases, with raw milk without the addition of starter cultures and under poor conditions of hygiene, it has a diverse unwanted microbial population. This aspect is characterized as a danger to consumers, as well as spoilage organisms that can also serve as a carrier of pathogenic microorganisms. The objective of this study is to isolate and identify lactic acid bacteria with probiotic characteristics and bacteriocinogenic from milk and artisan cheeses produced in this region. Thus initially the BAL were isolated and tested for antagonist ability against pathogens, and then checked the ability to produce antimicrobial substances of proteinaceous nature (bacteriocins), as well as resistance to biological barriers, as a criteria for the selection of isolated with probiotic potential. Molecular identification was performed by obtaining and sequencing of 16S rDNA or the ITS region. Subsequently, the isolated were evaluated for antimicrobial resistance of clinical use and the production of the enzyme β-hemolysin as virulence factors. The selected isolated were used as inoculum in cheese produced at a pilot level, with monitoring of physical-chemical and microbiological, over twenty-eight days of maturation under refrigeration. Of total lactic acid bacteria isolated twentyone (34.43%) showed antagonistic potential against pathogenic microorganisms reference. Of these, seven (33.33%) were able to produce antimicrobial substances of nature protein, being classified as possibly bacteriocinogenic and five (23.81%) isolated were shown to possess probiotic potential. The molecular identification of these proved to treat Enterococcus durans, Enterococcus faecium and Lactobacillus plantarum. The isolated F9 and U5 were selected and added as bacteriocin and probiotic culture, respectively, as a pilot project in cheese artificially contaminated with Listeria monocytogenes. No isolated was able to remove this pathogenic organism in the cheese, and the cultivation of bacteriocinogenic shown to be capable of maintaining viable cells of the microorganism stable during the maturation period. The probiotic proved to be able to withstand during the ripening of the cheese, while maintaining a viable cell number in the order of 107 - 108UFC.g-1 cheese, which allows its use with probiotic purpose. / Dentre a variada gama de produtos fermentados naturalmente por bactérias ácido láticas (BAL) encontram-se os queijos artesanais. Estas bactérias são inerentes da matéria-prima leite e durante o processo fermentativo produzem compostos responsáveis pelo flavor e textura dos produtos. Sua utilização constituise em uma das técnicas mais antigas de conservação de alimentos, já que são capazes de produzir substâncias com caráter antagônico frente a micro-organismos deteriorantes e patogênicos, com destaque a Listeria monocytogenes, comumente encontrada em produtos lácteos refrigerados. Além disso, muitas bactérias ácido láticas possuem potencial probiótico, constituindo-se em um atrativo a mais para sua utilização. Na região Fronteira Noroeste do Estado do Rio Grande do Sul é produzido um queijo típico, popularmente denominado queijo colonial, cujo conhecimento das técnicas de fabricação tem sido transferido verbalmente ao longo das gerações. Por ser fabricado, na grande maioria dos casos, com leite cru, sem a adição de culturas iniciadoras e sob condições deficientes de higiene, possui uma diversificada população microbiana indesejada. Este aspecto se caracteriza como um perigo aos consumidores, já que além de micro-organismos deteriorantes pode também servir como veículo de micro-organismos patogênicos. Assim, o objetivo do presente estudo foi isolar e identificar bactérias ácido láticas com características bacteriocinogênicas e probióticas, de leite e queijos artesanais desta região. Para isso, inicialmente, as BAL foram isoladas e testadas quanto a sua capacidade antagonista frente a micro-organismos patogênicos e então verificada a capacidade de produção de substâncias antimicrobianas de natureza protéica (bacteriocinas). A resistência a barreiras biológicas, como um dos critérios para seleção de isolados com potencial probiótico também foi avaliado. A identificação molecular dos isolados potencialmente bacteriocinogênicos e probióticos foi realizada por meio da obtenção e sequenciamento do rDNA 16S ou da região ITS. Posteriormente, os isolados foram avaliados quanto à resistência a antimicrobianos de uso clínico e à produção da enzima β-hemolisina, como fatores de virulência. Os isolados selecionados foram utilizados como inoculo em queijos produzidos a nível piloto, com monitoramento de parâmetros físico-químicos e microbiológicos, ao longo de vinte e oito dias de maturação, sob refrigeração. Do total de bactérias láticas isoladas, vinte e uma (34,43%) demonstraram potencial antagonista frente a micro-organismos patogênicos de referência. Destas, sete (33,33%) mostraram-se capazes de produzir substâncias antimicrobianas de natureza proteica, sendo classificadas como, possivelmente, bacteriocinogênicas e cinco (23,81%) dos isolados demonstraram possuir potencial probiótico. A identificação molecular destes revelou se tratarem de Enterococcus durans, Enterococcus faecium e Lactobacillus plantarum. Os isolados F9 e U5 foram selecionados e adicionados como cultura bacteriocinogênica e probiótica, respectivamente, em queijos a nível piloto, artificialmente contaminados com Listeria monocytogenes. Nenhum dos isolados foi capaz de eliminar este microorganismo patogênico nos queijos, porém o cultivo bacteriocinogênico se mostrou capaz de manter as contagens de células viáveis deste micro-organismo estáveis durante o período de maturação. A cultura probiótica se revelou capaz de resistir durante a maturação do queijo, mantendo um número de células viáveis na ordem de 107 - 108UFC.g-1 de queijo, o que permite sua utilização com propósito probiótico.

Abstract The aim of this work was to assess and improve the enrichment cultivation of food-contaminating bacteria prior to detection by means of RNA-based sandwich hybridization assay (SHA). The examples of beer-spoiling lactic acid bacteria (LAB) and food-borne Salmonella Typhimurium were selected based on their relevance in Finnish food industry. Also universal challenges affecting on the selection of the enrichment cultivation procedure are discussed, including some potential possibilities for improved enrichment cultivation. The results of this study may therefore be used for the assessment of the efficiency of bacterial cultivation in other applications. The evaluation of the enrichment cultivation procedures prior to SHA lead to following conclusions: i) the enrichment cultivation procedure is necessary prior to rRNA-based SHA, and it directly influences the accuracy of SHA; ii) the improvement of the enrichment cultivation may allow faster recovery and growth of bacteria; iii) the improved recovery of bacteria can be achieved by reducing environmental stress factors in the enrichment culture; and iv) the growth of bacteria may be accelerated by assuring the selectivity of medium and allowing accessibility to growth factors. Several growth factors were studied by means of full factorial design and response surface modeling. Measured cell densities, as well as predicted lag-times and maximum growth rates in the bacterial cultures were used as responses. The results show that small shifts in the cultivation conditions extend the lag-time and decrease the growth rate of both LAB and Salmonella. Besides adjusting the temperature and pH, the growth of LAB was facilitated by reducing osmotic and oxidative stresses in the enrichment medium. In this study, a novel enzyme controlled glucose delivery system was used for the first time in the enrichment cultivation of food-contaminating bacteria. The glucose delivery system improved the growth of LAB in single strain cultures and in actual brewing process samples. The recovery of injured Salmonella was also enhanced by using the glucose delivery system together with selective siderophore ferrioxamine E, both in terms of reduced lag-times and increased growth rates. Based on the SHA, the adjusted BPW broth enhanced the molecular detection of heat-injured Salmonella in meat.

Le présent travail porte sur l’étude comparative des procédés d’électrodialyse et d’électrodéionisation. Les possibilités d’application des procédés électro-membranaires à la production d’acide lactique par voie fermentaire sont investiguées. Deux axes de recherche sont choisis : le premier consiste à extraire de manière continue le lactate de sodium hors du milieu de fermentation. Pour cela, un empilement d’électrodialyse ne comportant que des membranes anioniques est couplé au fermenteur : environ 95 % des ions lactate sont extraits lors de l’opération. Par comparaison avec une fermentation témoin en mode batch, aucune inhibition de la fermentation n’est observée, et la productivité est multipliée par 13. Le deuxième axe de recherche consiste à convertir le lactate de sodium en acide lactique : un taux de purification comparable à celui obtenu en échange d’ions est recherché. Un procédé continu d’électrodéionisation à membranes bipolaires permettant d’atteindre 99,9 % de taux de conversion est élaboré pour le traitement de produit dilué. Est présentée finalement la modélisation mathématique d’un compartiment d’électodéionisation : les points expérimentaux sont fortement similaires aux points recalculés / This work deals with the comparative study of electrodialysis and electrodeionization. The possibilities to integrate the electro-membrane processes in the lactic acid fermentive production lines are investigated. Two main research ways are chosen : the first one lies in the continuous extraction of natrium lactate out of the fermentation middle. For this, an electrodialysis stack of only anionic membranes is coupled with the fermenter : approximately 95 % of lactate are removed during the operation. By comparison with a standard fermentation in batch mode, no inhibition is observed, and the productivity is increased by 13. The second way is to convert the natrium lactate in lactic acid : a high purity rate is seeked. A continuous electrodeioniation process including bipolar membranes, leading to 99,9% conversion rate, is elaborated for the treatment of diluted solutions. Finally is presented the mathematic calculation of an electrodeionization compartment : experimental points and calculated values are very similar

Doctor of Philosophy / Department of Grain Science and Industry / X. Susan Sun / Poly(lactic acid) (PLA), a synthetic biopolymer, is a promising substitute of some petroleum-based polymers due to its mechanical and biodegradable properties. But, because of the high cost of PLA (compared to those petroleum plastics for disposable application), starch has been incorporated into PLA to reduce cost and accelerate the biodegradability rate of the composites. But, the addition of starch as filler to PLA decreased mechanical performance of the composite. The addition of methylenediphenyl diisocyanate (MDI) into PLA/starch blends improved drastically the mechanical properties of the composite. Results from thermal-degradation analysis showed that PLA had the highest Arrhenius activation energy and strongest thermal endurance of all samples, followed by PLA/starch/MDI and PLA/starch. Aged samples exposed to fluctuating humidity storage conditions significantly decreased their performance. But, storing the samples in plastic bags could minimize degradation of properties. PLA and its composites with starch would not significantly affect application function when they are stored in controlled environment. PLA and PLA/starch based composites sealed in plastic bags can be stored in fluctuating humidity conditions (30-90% RH) for up to 30 days. Tensile strength, elongation, and damping increased with average particle size of starch granules (APS). But, declination of these properties was detected with APS larger than 45 mm. Crystallinity increased as the APS decreased. Young’s modulus, storage modulus, and moisture absorption were not significantly affected by the starch APS. The use of MDI as a coupling agent altered the role of starch APS on those properties of poly(lactic acid)/starch composite. The oxidation of the primary alcohol group on C6 of starch molecules up to 10% degree of substitution did not significantly affect the mechanical properties of PLA/starch/MDI, but the composites showed a reduced inelastic deformation (tensile curve) and significant increase in storage modulus and damping. Results suggest that a substitution of hydroxyl group on C6 of starch molecules for carboxyl group (up to 10%) increased the strengthening effect of MDI enough to reduce inelastic deformation of the composites upon load, but not enough to enhance mechanical properties.

Le psoriasis est une dermatose inflammatoire chronique affectant 2 à 3 % de la population européenne. Les cytokines pro-inflammatoires ont un rôle crucial dans la pathogénèse du psoriasis. Parmi les voies de signalisation cytokinique, l'étude de la voie JAK/STAT a conduit au développement de traitements systémiques efficaces. Cependant, les essais cliniques évaluant les inhibiteurs JAK/STAT impliquent en grande majorité des administrations orales, la voie topique restant marginale. Le développement de formulations innovantes pour application topique contenant des inhibiteurs JAK/STAT semble être une stratégie prometteuse dans le cadre du psoriasis. Les nanoparticules de poly(acide lactique) (NP PLA) développées au laboratoire ont été étudiées pour la délivrance topique de principes actifs. Ce sont des vecteurs efficaces, qui s'accumulent dans les follicules pileux. De plus, l'encapsulation d'actifs dans des NP PLA permet une libération spécifique au niveau du site d'action, et donc une réduction de la toxicité. L'objectif de ce travail est d'élaborer des formulations semi-solides de NP PLA contenant un inhibiteur JAK/STAT pour le traitement topique du psoriasis, tout en caractérisant un modèle in vivo de psoriasis induit par applications d'Imiquimod. Cette caractérisation des lésions psoriasiformes permettra l'évaluation in vivo des nanoformulations topiques contenant des inhibiteurs JAK/STAT. Cinq formulations ont été élaborées puis caractérisées afin de répondre aux attentes galéniques pour une application topique. L'intégrité des NP PLA a été vérifiée, et la pénétration/perméation de molécules modèles à travers de la peau de souris inflammée a été évaluée / Psoriasis is a chronic inflammatory skin disease, affecting 2 to 3 % of European population. Inflammatory cytokines play a crucial role in the pathogenesis of psoriasis. Among cytokines signaling pathways, JAK/STAT pathway has been widely investigated, leading to the development of efficient systemic agents. However, current clinical trials evaluating JAK/Sat inhibitors mainly involve oral administrations, with few investigations on topical route. Developing innovative drug delivery systems for topical application of JAK/STAT inhibitors seems a promising strategy for psoriasis treatment. Poly(lactic acid) nanoparticles (PLA NPs) developed in the laboratory have been widely investigated for topical drug delivery and are efficient carriers for local dermatotherapy, especially through hair follicles. Moreover, drug encapsulation in PLA NPs for topical delivery allows a specific delivery to the site of action, and thus a decreased toxicity.The aim of this work was to elaborate semi-solid formulations of PLA NPs containing JAK/STAT inhibitors for topical treatment of psoriasis, while characterizing an in vivo model of Imiquimod-induced psoriasis in mice. This characterization of psoriasis-like skin lesions in Imiquimod treated mice provided key tools for in vivo evaluation of topical nanoformulations containing JAK/STAT inhibitors. Five formulations have been developed and then characterized in order to meet galenic criteria for topical drug administration. PLA NPs integrity was assessed, and penetration/permeation profiles of model dugs through inflamed mice skin were determined

Orientador: Ranulfo Monte Alegre / Dissertação (mestrado) - Universidade Estsadual de Cam,pinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-18T17:54:10Z (GMT). No. of bitstreams: 1 AlcazarAlay_SylviaCarolina_M.pdf: 2176104 bytes, checksum: 32f8cdfe0b86e00e15edc533c76b33cb (MD5) Previous issue date: 2011 / Resumo: O interesse pela produção de ácido láctico tem crescido fortemente nos últimos anos desde a descoberta das propriedades de seus polímeros, os que apresentam caraterísticas de biodegradabilidade e biocompatibilidade; e sua aplicação como solvente ¿verde¿ ou ambientalmente saudável para os processos de misturas de solventes na indústria química. Dado o potencial econômico do ácido láctico, são necessários processos mais eficazes para sua síntese e redução dos custos de produção. Este trabalho visou aperfeiçoar o processo de produção fermentativa do ácido láctico, determinando formulações do meio de cultura que auxiliarão no desenvolvimento de tecnologias competitivas de produção. Além disso, esse trabalho propõe a utilização de matérias-primas de baixo custo e grande disponibilidade no mercado brasileiro como por exemplo melaço de cana e água de maceração de milho. A espécie selecionada para o estudo foi Lactobacillus delbrueckii, duas linhagens foram estudadas, selecionando-se a que apresentou maior velocidade de crescimento e produção de ácido láctico no meio de cultura padrão. O estudo de otimização da produção de ácido láctico foi realizado utilizando a estratégia de planejamentos experimentais. O uso de melaço de cana e água de maceração de milho como fonte de carbono e nitrogênio, em concentração de 240 gL-1 e 14 gL-1 respectivamente, possibilitou produtividade de até 57,17 gL-1 após 96 horas, com eficiência de 82% (gramas de ácido láctico produzido / grama de substrato utilizado) / Abstract: The interest in lactic acid has grown strongly in the last years since the discovery of its properties of application in production of biodegradable and biocompatible polylactate polymers and their application as "green solvent¿ or ¿safety solvent¿ to processes of mixtures of solvents in the chemical industry. Considering the commercial potential of lactic acid, more efficient processes are needed for its synthesis, reducing costs of production and turning its industrial application more atractive, as its cost still prevents it from being used in some areas. This work aimed at improving the process of fermentative lactic acid production, determining formulations that will help develop competitive technologies of production. Furthermore, the use of low cost raw materials, easily available on the brazilian market, such as sugarcane molasses and corn steep liquor is proposed. The species selected for the study was Lactobacillus delbrueckii, two strains were studied, Lactobacillus delbrueckii spp. bulgaricus, shown the greatest growth speed and lactic acid production in the standard culture medium. The optimization study of lactic acid production was performed using the strategy of experimental design, using sugarcane molasses as a carbon source and corn steep liquor as a nitrogen source allowed a productivity of up to 57,17 gL-1 after 96 hours, with 82% lactic acid yield efficiency (g lactic acid produced / g substrate utilized) using an initial concentration of 240 gL-1 and 14 gL-1 of sugarcane molasses and corn steep liquor respectively / Mestrado / Engenharia de Alimentos / Mestre em Engenharia de Alimentos