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Alginates are (1and4) linked linear copolysaccharides composed of B-D-mannuronic acid (M) and its C-5 epimer, a-L-guluronic acid (G). Several strategies to synthesize organically modified alginate derivatives have been reported, but almost all chemistries are performed in either aqueous or aqueous-organic media. The ability to react alginates homogeneously in organic solvents would open up access to a wide range of new chemistries and derivatives. However, past attempts have been restricted by the absence of methods for alginate dissolution in organic media. We therefore report a strategy to solubilize tetrabutylammonium (TBA) salts of alginic acid in polar aprotic solvents containing tetrabutylammonium fluoride (TBAF). Acylation of TBA-alginate was performed in DMSO/TBAF to get products with DSacetyl up to ~ 1.0. We further report that by using appropriate solvent conditions, placement of acyl groups can be controlled to achieve either random or M-selective substitution. Alginate acetates synthesized in an M-selective fashion were used to study the ability of these derivatives to form Ca-crosslinked hydrogels. Detailed structure-property analyses were performed to identify acetylation reaction conditions and product properties that may be ideal for hydrogel formation. Furthermore, alginate esters were synthesized via modification of carboxylate groups on the backbone. These derivatives dissolved in polar aprotic solvents without the need to add TBAF. A proof of concept study showed their utility in the solubility enhancement of the poorly water soluble flavonoid naringenin. / Ph. D.

Starch is used in many food applications as thickeners, texturisers and fat substitutes. Native starches, although useful, have low stability to conditions such as high shear, extreme pH and high temperatures encountered during food processing. Starches are modified to make them more suitable for processing conditions. The modification of starch by the use of a naturally occurring compound (for example stearic acid) may produce desirable properties and also removes the risk of a chemical residue in the starch. Starch can be from several grain sources. Teff grain is highly underutilized and underresearched. The work conducted in this project investigates the pasting properties, gelling tendencies, clarity and flow properties (using a rheometer) of teff starch pastes treated with stearic acid, in comparison to maize starch pastes. X-Ray Diffraction (XRD) and Confocal Laser Scanning Microscopy (CLSM) were also used to investigate the possible impact of stearic acid on the structure of the starch granules and pastes. Starch suspensions containing stearic acid (0.25% - 4%) were pasted in a Rapid Visco Analyser using a short pasting cycle of approx. 30 min (held for 5 min at 91°C). Maize starch (treatments) showed a reduced peak viscosity within the holding period, while teff starch (treatments) did not. Teff starch showed increasing viscosity without reaching a peak during the holding time. The pasting cycles were then extended (holding time extended to 2 hr) to investigate the pasting behaviour of teff starch. The extended pasting cycle resulted in a reduced first viscosity peak for maize starch with added stearic acid. Teff starch with added stearic acid showed a large increase in viscosity without the formation of the first viscosity peak. However, both starches displayed a second pasting peak. The addition of stearic acid resulted in an increase in the viscosity of the second pasting peak from about 175 Rapid Visco Units (RVU) to 228 RVU for maize starch, and from 113 RVU to 250 RVU for teff starch. The final viscosity of maize starch increased from 186 RVU to 227 RVU, while that of teff starch increased from 194 RVU to 261 RVU. The second viscosity peak was not observed with waxy maize starch (approx. 97% amylopectin). This suggests that amylose-stearic acid complexation might have been responsible for the formation of this peak. Complexation Index (CI) values increased as the concentration of stearic acid was increased. This further suggests that some interaction between amylose and stearic acid had taken place. The pastes of maize and teff starches modified with stearic acid were more opaque and showed reduced gelling compared to their non-modified counterparts. Maize and teff starches and their stearic acid-treated counterparts followed the Power-Law Model and were shear thinning (n < 1). However, teff starch pastes (control and treatment) seemed to be less shear thinning than their maize starch paste counterparts. An increase in consistency, k, after the extended pasting cycle was used (compared to the short pasting cycle) for the treated starches, reflects the increased viscosities obtained during extended pasting. XRD further suggested that amylose-lipid complexes may have been present in the starch pastes (after extended pasting) due to the occurrence of the 4.4 Å and 12 Å peaks (characteristic of V-type starches). CLSM showed that stearic acid diffused into maize starch granules but not into teff starch granules. This was probably due to the pores of the surfaces of maize starch granules which may have facilitated the diffusion process. In contrast, teff starch granules do not have pores on their surfaces. This structural difference may be attributed for the pasting differences between teff and maize starches. The effects of stearic acid on the pasting (effect on first and second peaks and final viscosity), and functional properties (reduced gelling and increased opacity of pastes) of maize and teff starches have been attributed to the formation of amylose-lipid complexes. These high viscosity and low gelling starches may be extremely useful as fat replacers. Teff starch has the added benefit of its small starch granules which may add to its ability mimic the mouthfeel of fat globules. / Dissertation (MSc)--University of Pretoria, 2011. / Food Science / unrestricted

is a major polysaccharide of the plant cell wall which is known to play a role in many mechanical functionalities, especially when a gel is formed in the presence of calcium. Understanding the gelling abilities of pectin is of great interest to the food industry also, since pectin is a widely used as a gelling agent and thickener. The aim of this study was to apply two complementary microrheological techniques to these systems, multiple particle tracking (MPT) and a light scattering technique called diffusing wave spectroscopy (DWS). While the first one provides fundamental information about the homogeneity of the studied gel, the second gives access to the high frequency behaviour, related to the nature of the basic strands of the network. Firstly, after verifying the validity of the experimental apparati and analysis approaches in a series of careful control experiments on archetypal systems, a regime where pectin gels exhibit the signatures of semi-flexible networks was identified in experiments carried out on gels made of pectin chains pre-engineered by enzymatic deesterification and subsequently assembled with the release of Ca2+. These results were the first showing that polysaccharides networks could be accommodated within the framework of semi-flexible networks, which have become a paradigm for biological gels, such as the well-known F-actin solutions present in the cell cytoskeleton. However, in the plant cell wall, where calcium is already present, the assembly mechanism could be controlled in a different manner, and a more biologically relevant system was studied where the action of the plant enzyme pectinmethylesterase was used to liberate ion-binding groups in the presence of Ca2+. Gels formed according to this alternative methodology were found to behave as punctually cross-linked flexible networks, strikingly different from the first results. This would be explained by the presence of short blocks of charged residues. Finally, experiments on pectins carried out with controlled blocky structures showed that a pectin made of short blocks can exhibit both sorts of network, depending on the polymer and Ca2+ concentrations. This lead naturally to the construction of a state diagram for the regimes of assembly, with proposed control parameters being the polymer concentration and the ratio of the amount of Ca2+ to the quantity of pectic residues which can effectively bind the calcium into cross-links, christened Reff.

Orientadores: Marise Aparecida Rodrigues Pollonio, Rosiane Lopes da Cunha / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-24T20:44:17Z (GMT). No. of bitstreams: 1 Felisberto_MariaHerminiaFerrari_M.pdf: 3031353 bytes, checksum: 5dd7de9b31750d6e8fa426fc6297bf3b (MD5) Previous issue date: 2014 / Resumo: A correlação entre dieta e saúde tem levado muitos setores da indústria de alimentos a reformularem seus produtos, com apelos mais saudáveis que possam resultar em reais benefícios para o consumidor. A elevada ingestão de sódio e de gordura está diretamente correlacionada com elevada propensão à hipertensão e doenças cardiovasculares, e os produtos cárneos, especialmente os produtos emulsionados, caracterizam-se por apresentarem elevados teores destes ingredientes em sua composição. A redução do sal, gordura e incorporação de fibras, figuram como as principais reformulações estratégicas para que o segmento ganhe competitividade e conquiste o mercado consumidor. O presente trabalho teve por objetivo avaliar as propriedades físico-químicas, tecnológicas e reológicas de um produto cárneo emulsionado, com redução simultânea de 50 % dos teores de sal e gordura, utilizando-se quatro fibras prebióticas (inulina, fruto-oligossacarídeo - FOS, amido resistente e polidextrose) em dois níveis (3 e 6 %). Com relação às propriedades tecnológicas, a adição das fibras prebióticas promoveu a formação de um produto menos estável, com elevada perda de líquido após o cozimento, principalmente nas formulações adicionadas de inulina e polidextrose. A adição das fibras prebióticas também promoveu alterações significativas com relação aos parâmetros instrumentais de textura, com redução dos índices de dureza. Os parâmetros de coloração do batter apresentaram diferenças significativas com relação ao índice de luminosidade (L*) e de vermelho (a*). Com relação às propriedades reológicas, os ensaios oscilatórios caracterizaram o material como elástico, uma vez que os módulos de G? mantiveram-se superiores aos de G" durante todo o ensaio de temperatura. Na avaliação da textura da emulsão crua (batter), as formulações adicionadas de FOS apresentaram os maiores valores para a força de penetração, devido provavelmente ao reduzido tamanho de cadeia desta molécula. Já nas mortadelas (produto cozido), os maiores valores para força de compressão foram observados para as formulações controle FC1, FC2 e FC3, pois a simultânea redução do sal e da gordura (F1) promoveu redução significativa na força de compressão. A avaliação das microestruturas confirma estes resultados evidenciando formulações controle com uma estrutura bastante compacta e densa, e as formulações adicionadas das fibras prebióticas apresentando uma rede bem menos densa e bastante porosa. Os resultados obtidos no presente estudo demonstram que a redução dos teores de gordura e de NaCl, com a simultânea adição de fibras prebióticas pode ser viável, sob o ponto de vista tecnológico, desde que se utilize algum ingrediente capaz de amenizar os efeitos causados na matriz, como por exemplo, a menor capacidade de retenção de água, elevada exsudação de líquido e formação de uma estrutura bastante porosa / Abstract: The correlation between diet and health has led many sectors of the food industry to reformulate their products with healthier appeals that could result in real benefits for the consumer. A high intake of sodium and fat is directly related to higher propensity to hypertension and cardiovascular disease, and the meat products, especially the emulsified products are characterized by high levels of these ingredients on its composition. The reduction of salt, fat and incorporation of fibers is considered as the major strategic reformulations for the segment becomes competitive and earn the consumer market. The aimed of this study was to evaluate the physicochemical, technological and rheological properties of meat emulsions with 50 % of reduction of salt and fat simultaneously, and the addition of four different prebiotic fibers (inulin, fructooligosaccharides - FOS, polydextrose and resistant starch) in two levels (3 and 6 %). Concerning to the technological properties, the addition of prebiotic fibers promoted the formation of a less stable product with a high fluid loss after cooking, especially in formulations added of inulin and polydextrose. The addition of prebiotic fibers also promoted significant changes on texture parameters, resulting in lower hardness values. The color parameters of batters showed significant differences from the luminosity (L*) and redness (a*) values. Concerning to the rheological properties, the oscillatory measurements characterized the material as elastic, due the modules G' remained higher than G" for the whole test temperature. In respect to texture parameters on the batters (raw emulsion), formulations added of FOS presented the greatest values for the penetration force, probably due to the small size of this molecule chain. On the bologna (cooked emulsion) higher values for compressive strength were observed for the control formulations FC1, FC2 and FC3, despite simultaneous reduction of salt and fat (F1) have promoted significant reduction on the compressive strength. Evaluation of microstructures confirm these results showing control formulations with a very compact and dense structure, and added formulations of prebiotic fibers presenting a much less dense and highly porous network. The results from this study demonstrate that the reduction of fat and NaCl, with the simultaneous addition of prebiotic fibers is feasible under the technological point of view. But, it is necessary to use an ingredient able of mitigate the effects on the matrix, for example less water holding capacity, high exsudation of liquid after cooking and the formation of highly porous network / Mestrado / Tecnologia de Alimentos / Mestra em Tecnologia de Alimentos

A comprovação de que siRNA pode ser usado para supressão de genes em diferentes células de mamíferos atraiu grande atenção como nova possibilidade de tratamento para diversas doenças. No entanto, para aplicação terapêutica de siRNA é necessário o desenvolvimento de um sistema de liberação efetivo e não tóxico, que permita a captação celular do siRNA e também que evite a sua degradação por enzimas. A capacidade de supressão de genes promovido pelo siRNA depende tanto do número de moléculas de siRNA transfectadas quanto da taxa de duplicação da célula. Uma das formas farmacêuticas que vem sendo amplamente utilizadas na literatura com o objetivo de prolongar e proteger a liberação de fármacos são as formulações com capacidade de formação de gel in situ. Desta forma, a presente pesquisa teve por objetivo o desenvolvimento farmacotécnico de formulações líquido cristalinas com formação de gel in situ após administração por via subcutânea para veiculação sustentada de siRNA. Misturas adequadas de monoleína, propilenoglicol, tampão Tris e polietilenoimina ou oleilamina (polímero e lipídeo catiônico, respectivamente) formaram sistemas precursores capazes de se geleificar in situ com excesso de água e, como demonstrado pelo estudo de absorção de água, a formação do gel é um processo rápido. As formulações desenvolvidas também foram eficientes para complexar o siRNA comprovando a importância da incorporação dos aditivos catiônicos aos sistemas. A liberação in vitro dos sistemas líquido cristalinos mostraram que a liberação é dependente da taxa de absorção de água e os estudos in vivo em modelo animal para avaliação da formação do gel in situ e toxicidade demonstraram que o gel se forma in vivo com a absorção de água dos fluidos corporais, sendo biodegradável e biocompatível. Os sistemas desenvolvidos mostraram-se promissores para o tratamento de doenças onde a administração localizada e sustentada de siRNA é necessária. / The evidence that siRNA can be used for suppression of genes in different mammalian cells attracted wide attention as a new possibility of treatment for various diseases. However, for siRNA therapeutic application is necessary to develop an effective non-toxic delivery system, which facilitate the siRNA cell uptake and avoid its degradation by enzymes. The genes suppression promoted by siRNA depends on the number of siRNA molecules transfected as the cell replication rate. One of the dosage forms that have been widely used in literature in order to prolong and protect the drug release is the in situ gelling formulations. Thus, the present study aimed the development and characterization of the in situ gelling liquid crystal-based systems for subcutaneous application of siRNA in gene therapy. Appropriate mixtures of monoolein, propylene glycol, Tris buffer and polyethyleneimine or oleylamine (cationic polymer and lipid, respectively) was able to form precursor formulation that gelling in water excess and, as demonstrated by the swelling studies, the gel formation is a fast process. The developed formulations were also effective for complexing the siRNA, indicating the importance of the incorporation of cationic additives in the systems. The in vitro release study showed that the release is dependent on the water absorption rate. In vivo studies in animal models have shown the gel is formed in vivo after water uptake of body fluids, and it is biodegradable and biocompatible. The systems developed are promising for the treatment of diseases where the local and sustained administration of siRNA is necessary.

A comprovação de que siRNA pode ser usado para supressão de genes em diferentes células de mamíferos atraiu grande atenção como nova possibilidade de tratamento para diversas doenças. No entanto, para aplicação terapêutica de siRNA é necessário o desenvolvimento de um sistema de liberação efetivo e não tóxico, que permita a captação celular do siRNA e também que evite a sua degradação por enzimas. A capacidade de supressão de genes promovido pelo siRNA depende tanto do número de moléculas de siRNA transfectadas quanto da taxa de duplicação da célula. Uma das formas farmacêuticas que vem sendo amplamente utilizadas na literatura com o objetivo de prolongar e proteger a liberação de fármacos são as formulações com capacidade de formação de gel in situ. Desta forma, a presente pesquisa teve por objetivo o desenvolvimento farmacotécnico de formulações líquido cristalinas com formação de gel in situ após administração por via subcutânea para veiculação sustentada de siRNA. Misturas adequadas de monoleína, propilenoglicol, tampão Tris e polietilenoimina ou oleilamina (polímero e lipídeo catiônico, respectivamente) formaram sistemas precursores capazes de se geleificar in situ com excesso de água e, como demonstrado pelo estudo de absorção de água, a formação do gel é um processo rápido. As formulações desenvolvidas também foram eficientes para complexar o siRNA comprovando a importância da incorporação dos aditivos catiônicos aos sistemas. A liberação in vitro dos sistemas líquido cristalinos mostraram que a liberação é dependente da taxa de absorção de água e os estudos in vivo em modelo animal para avaliação da formação do gel in situ e toxicidade demonstraram que o gel se forma in vivo com a absorção de água dos fluidos corporais, sendo biodegradável e biocompatível. Os sistemas desenvolvidos mostraram-se promissores para o tratamento de doenças onde a administração localizada e sustentada de siRNA é necessária. / The evidence that siRNA can be used for suppression of genes in different mammalian cells attracted wide attention as a new possibility of treatment for various diseases. However, for siRNA therapeutic application is necessary to develop an effective non-toxic delivery system, which facilitate the siRNA cell uptake and avoid its degradation by enzymes. The genes suppression promoted by siRNA depends on the number of siRNA molecules transfected as the cell replication rate. One of the dosage forms that have been widely used in literature in order to prolong and protect the drug release is the in situ gelling formulations. Thus, the present study aimed the development and characterization of the in situ gelling liquid crystal-based systems for subcutaneous application of siRNA in gene therapy. Appropriate mixtures of monoolein, propylene glycol, Tris buffer and polyethyleneimine or oleylamine (cationic polymer and lipid, respectively) was able to form precursor formulation that gelling in water excess and, as demonstrated by the swelling studies, the gel formation is a fast process. The developed formulations were also effective for complexing the siRNA, indicating the importance of the incorporation of cationic additives in the systems. The in vitro release study showed that the release is dependent on the water absorption rate. In vivo studies in animal models have shown the gel is formed in vivo after water uptake of body fluids, and it is biodegradable and biocompatible. The systems developed are promising for the treatment of diseases where the local and sustained administration of siRNA is necessary.

The thesis deals with the possibility of bonding the ceramic mixture by a sol-gel method, Colloidal alumina was used as the sol and the gelation was performed by changing the ionic strength or pH. The influence of different gelling agents (NaCl, NH4Cl, NH3, MgO a CO(NH)) on the gellation time and on the course of the gelation was compared. The aim of the work is the preparation of refractory monolith with the highest packing desity possible, which was solved by modeling the granulometric curve of the solid part of the ceramic mixture based on alumina. The thesis also describes the behavior of prepared gels during thermal processing of ceramics. Subsequently the resulting structure of prepared ceramic bodies was monitored.