Made available in DSpace on 2014-10-09T12:51:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:12Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:51:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:12Z (GMT). No. of bitstreams: 0 / Carragenanas, agaranas e alginatos são hidrocolóides largamente utilizados em todo tipo de produtos alimentícios como aditivos espessantes. Eles não são absorvidos pelo organismo e, portanto não introduzem calorias extras na dieta. A irradiação se apresenta com grande potencial como um método alternativo na preservação de alimentos pois não induz aumento da temperatura, e é, portanto, de grande eficácia na descontaminação de ingredientes alimentícios sensíveis ao calor. Neste trabalho, soluções dos hidrocolóides agararana, carragenana e aiginato de sódio, foram irradiadas com diferentes doses (0-10 kGy) de radiação gama de Co-60 na presença de antioxidantes também utilizados na indústria alimentícia: ácido ascórbico, extrato vegetal de rosela (Híbiscus sabdariffa L.) e isofiavona de soja. As soluções dos polissacarídeos comestíveis agarana, carragenana e alginato de sódio mostraram ser bons sistemas para avaliar o efeito da radiação ionizante por apresentarem radiossensibilidade característica medida pelas mudanças na viscosidade. Os resultados obtidos mostram que esses antioxidantes apresentam, no geral, ação radioprotetora o que pode ser de grande valia nas aplicações futuras da irradiação de alimentos em escala comercial. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Orientador: Theo Guenter Kieckbusch / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T12:31:13Z (GMT). No. of bitstreams: 1 Turbiani_FrancieleRezendeBarbosa_M.pdf: 2355251 bytes, checksum: 54057feae41bd47bee56d5615dbbfd3d (MD5) Previous issue date: 2007 / Resumo: Filmes biodegradáveis são produzidos a partir de polímeros naturais, principalmente polissacarídeos e proteínas, e tem potencial aplicação na área médica, farmacêutica e alimentícia. A incorporação de agentes ativos pode ampliar suas funções como embalagens antimicrobianas, por exemplo. Filmes foram confeccionados à base de alginato de sódio usando cloreto de cálcio como agente reticulante e glicerol como plastificante. O uso de benzoato de cálcio foi investigado como agente ativo (íons benzoato) e como auxiliar na reticulação (íons cálcio). Devido ao alto poder gelificante do Ca++, confeccionou-se, inicialmente, um filme de baixa reticulação a partir de soluções filmogênicas contendo até 0,54% de Ca++ (1º estágio). Esse filme sofreu uma reticulação complementar com excesso de Ca++ (2º estágio). Dentre os vários procedimentos avaliados (contato do filme com tecido e/ou esponja umidecidas, pincel ou rolo de pintura e imersão do filme em solução reticuladora), a simples imersão em solução contendo de 3 a 7% de CaCl2 no 2º estágio produziu filmes com alto grau de reticulação. O aumento da concentração de glicerol nessa solução melhora a manuseabilidade e plasticidade dos filmes, porém aumenta a solubilidade em água e o conteúdo de umidade dos mesmos e um adequado compromisso foi obtido usando 5% desse plastificante. Ensaios nos quais o CaCl2 foi substituído, total ou parcialmente, por benzoato de cálcio indicou que o mesmo não pode ser usado na solução do 2º estágio por favorecer a precipitação de cristais sobre o filme. Filmes ativos de 0,06 mm de espessura, pré-reticulados apenas com benzoato de cálcio e 0,7% de glicerol na solução do 1º estágio e imersos por 30 minutos em banho contendo 3% de CaCl2 e 5% de glicerol no 2º estágio, apresentaram baixa solubilidade em água (até 20% da matéria seca). Estes filmes têm baixo grau de intumescimento (< 50% da massa inicial), boa resistência mecânica à tração, mas baixa elasticidade. A permeabilidade ao vapor de água é moderada e os valores encontrados são típicos de biofilmes hidrofílicos. Ensaios de liberação de benzoato utilizando água como sorvedouro, apresentaram bom ajuste as soluções da 2ª Lei de Fick, com valores de difusividade efetiva do benzoato variando de 3 a 5.10-7 cm2/s. Os valores de difusividade diminuiram com o aumento da reticulação e aumentaram com o aumento da concentração de benzoato no filme / Abstract: Biodegradable films are produced from natural polymers, structurized mainly by polysaccharides or proteins, and have potential applications in the medical, pharmaceutical or food area. The incorporation of active agents can extend their application as antimicotic packaging, for instance. Films were manufactured with sodium alginate, using calcium chloride as cross-linking agent and glycerol as plasticizer. The use of calcium benzoate as active agent (benzoate ions) and as crosslinking agent (calcium ions) was investigated. Due to the strong gelling power of Ca++ ions, impeding smooth casting procedures, films with low reticulation are initially manufactured, using less than 0.54% Ca++ in the filmogenic solutions (1st stage). These films are further crosslinked with an excess of Ca++ by immersion in a solution of 3% to 7% of CaCl2 (2nd stage). Increasing the glycerol concentration in this solution improves the handling and plasticity of the films but increase water solubility and moisture content and an adequate compromise was obtained using 5% plasticizer. Tests conducted with partial or total substitution of CaCl2 by calcium benzoate indicated that the later could not be used in the 2nd stage solution since it promoted crystals precipitation on film surface. Active films, 0.06mm thick, pre-reticulated with calcium benzoate only and with 0.7% glycerol in the solution of the 1st stage, immersed for 30 minutes in a 3% CaCl2 and 5% glycerol solution (2nd stage) had around 17% moisture content and low water solubility (up to 20% of total dry mass). These films show low swelling degree (<50% of initial mass), good tension strength but low elongation ability. The water vapor permeability is moderate, typical of highly hydrophilic films. Benzoate liberation tests, using pure water as sink, presented good fit to solutions of Fick¿s 2nd law and effective diffusivities found varied from 4.2 to 6.3 × 10-7 cm2/s. The diffusivity values decreased with the degree of reticulation and increase with benzoate concentration in the film / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Orientador: Ângela Maria Moraes / Dissertação (mestrado-) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-22T01:56:28Z (GMT). No. of bitstreams: 1 Pires_AnaLuizaResende_M.pdf: 3161193 bytes, checksum: c48592744224fd8b24f5563cdc1a3415 (MD5) Previous issue date: 2013 / Resumo: Polímeros biodegradáveis estão sendo amplamente aplicados na constituição de curativos para o tratamento de lesões de pele de diferentes origens, estando a quitosana e o alginato dentre os mais estudados. A associação de alginato e quitosana em curativos pode atuar de maneira positiva na absorção de fluidos das lesões, além de propiciar a incorporação de fármacos. Entretanto, a flexibilidade do dispositivo é baixa e o processo de obtenção é lento em função de etapas como a correção do pH para a neutralidade, secagem e reticulação. Neste trabalho teve-se por objetivo melhorar as propriedades mecânicas de membranas de quitosana e alginato pela incorporação de um gel de silicone comercial (Silpuran® 2130 A/B), avaliar os efeitos da correção do pH em etapa única, da temperatura de secagem e também da eliminação das etapas de reticulação nas características de membranas de quitosana e alginato na presença e ausência de AlphaSan®RC2000, um agente microbicida à base de prata. As membranas foram caracterizadas quanto à espessura, à absorção de fluidos, à perda de massa quando expostas a diferentes fluidos fisiológicos e à resistência mecânica. Análises complementares de FTIR e EDS também foram realizadas. Os resultados obtidos mostraram que as membranas secas a 60 °C apresentaram superfície mais lisa que as secas a 37 °C. A espessura diminuiu com a correção do pH para 7,0 e aumentou na presença de AlphaSan®RC2000. Para as formulações livres do antimicrobiano, a elevação do pH aumentou a absorção de soro fetal bovino e solução salina e aumentou também a perda de massa nesta última solução. Já as amostras obtidas na presença de AlphaSan® RC2000 apresentaram aumento na absorção de água. A elevação da temperatura reduziu somente a perda de massa após o contato com a água. A reticulação, após a secagem, com CaCl2 a 2% mostrou-se indispensável para a estabilização das membranas, resultando em materiais com aspecto mais rugoso e maior espessura. A absorção de fluidos, a estabilidade em diferentes fluidos e a resistência mecânica diminuíram tanto na presença quanto na ausência de prata. Análises por EDS e FTIR mostraram que tanto o AlphaSan® RC2000 quanto o Silpuran® 2130 A/B, não são removidos após a etapa de lavagem das membranas. As formulações contendo o composto siliconado apresentaram-se mais homogêneas, flexíveis e com maior caráter adesivo, assim como menor espessura. A absorção de soluções por estas formulações foi menor e a estabilidade em solução foi maior. A resistência mecânica aumentou significativamente com a incorporação de silicone, atingindo-se uma tensão de ruptura máxima de 63 MPa. Dessa forma, é viável a diminuição do tempo de processamento das membranas pelo ajuste do pH em etapa única, pelo uso de temperaturas mais elevadas de secagem e pela eliminação da etapa de reticulação primária. A incorporação de Silpuran® 2130 A/B mostrou-se uma boa alternativa para a melhora das propriedades mecânicas dos curativos de quitosana e alginato / Abstract: Biodegradable polymers are widely applied in the constitution of dressings for treating various types of skin lesions, being chitosan and alginate two of the most studied raw materials. The association between alginate and chitosan in wound dressings can act positively in the absorption of fluids from lesions, allowing also the incorporation of drugs. However, the device flexibility is frequently low and its production is time-consuming due to steps such as adjusting the pH to neutrality, sample drying and crosslinking. This study aimed to improve the mechanical properties of chitosan-alginate wound dressings by incorporating a commercial silicone gel (Silpuran® 2130 A/B) and to evaluate the effects of pH correction in one step, of the drying temperature and also of the elimination of the crosslinking steps in the characteristics of chitosan-alginate membranes obtained in the presence and absence of AlphaSan® RC2000, an antimicrobial agent containing silver in its composition. The membranes were characterized regarding thickness, absorption of fluids, mass loss in different fluids and mechanical resistance. Complementary analyzes of FTIR and EDS were also performed. The results showed that membranes dried at 60 °C presented smoother surfaces than when dried at 37 °C. Membrane thickness decreased with the correction of the pH to 7,0 and increased in the presence of AlphaSan® RC2000. For formulations free of the antimicrobial agent, the pH adjustment increased bovine fetal serum and saline solution absorption, increasing also sample mass loss in the latter solution. Devices containing AlphaSan® RC2000, on the other hand, had increased water absorption. The increase of drying temperature, however, reduced mass loss due to prolonged contact with water. The crosslinking with CaCl2 2% after a drying step was shown to be essential for membrane stabilization, conducting to materials with less smooth surfaces and with greater thickness. The absorption of fluids decreased for samples prepared both in the presence and absence of silver, as did membrane stability and mechanical properties. EDS and FTIR analyzes showed that both AlphaSan® RC2000 and Silpuran® 2130 A/B were not removed from the membranes after the washing step. The formulations incorporating the silicone compound showed more homogeneous surfaces, greater flexibility and adhesivity, as well as lower thickness. The solution absorption was lower and membrane stability was higher for those devices. The mechanical strength increased with the incorporation of silicone, reaching a maximum of 63 MPa. Thus, it is viable to decrease the processing time of the membranes by pH adjustment in a single step, through the use of higher temperatures during drying and by the eliminating of the primary crosslinking step. The incorporation of Silpuran® 2130 A/B proved to be a good alternative for the improvement of the mechanical properties of chitosan and alginate dressings / Mestrado / Desenvolvimento de Processos Biotecnologicos / Mestra em Engenharia Química

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1983. / Extra t.p. with thesis statement inserted. Includes the author's seven published papers. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

by Li Yung Yung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 105-121). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.i / ABSTRACT (ENGLISH VERSION) --- p.ii / ABSTRACT (CHINESE VERSION) --- p.iv / TABLE OF CONTENTS --- p.v / LIST OF TABLES --- p.x / LIST OF FIGURES --- p.xi / LIST OF ABBREVIATIONS --- p.xiii / Chapter CHAPTER ONE --- INTRODUCTION / Chapter 1.1 --- Seaweed --- p.1 / Chapter 1.1.1 --- General Introduction --- p.1 / Chapter 1.1.2 --- Classification and Use of Seaweed --- p.1 / Chapter 1.1.3 --- Phycocolloids --- p.2 / Chapter 1.1.4 --- Hong Kong Seaweed --- p.3 / Chapter 1.1.4.1 --- Sargassum Species --- p.3 / Chapter 1.1.4.2 --- Padina Species --- p.5 / Chapter 1.2 --- Source and Production of Alginate --- p.8 / Chapter 1.2.1 --- Function of Alginate in Seaweed --- p.8 / Chapter 1.2.2 --- Chemical Structure of Alginate --- p.8 / Chapter 1.2.3 --- Alginate Production --- p.9 / Chapter 1.2.4 --- Isolation of Alginate --- p.13 / Chapter 1.2.5 --- Commercial Methods --- p.13 / Chapter 1.3 --- Application of Alginate --- p.14 / Chapter 1.3.1 --- Industrial Application --- p.14 / Chapter 1.3.2 --- Pharmaceutical Application --- p.16 / Chapter 1.3.3 --- Food Application --- p.17 / Chapter 1.3.3.1 --- Uses of Alginate in Food --- p.17 / Chapter 1.3.3.2 --- Safety --- p.19 / Chapter 1.4 --- Structure and Function Relationship of Alginate --- p.19 / Chapter 1.4.1 --- Physico-Chemical Properties --- p.21 / Chapter 1.4.1.1 --- M/G ratio --- p.21 / Chapter 1.4.1.2 --- Solution Properties --- p.21 / Chapter 1.4.1.3 --- Viscosity --- p.23 / Chapter 1.4.1.4 --- Molecular Weight --- p.27 / Chapter 1.4.2 --- Functional Properties --- p.27 / Chapter 1.4.2.1 --- Emulsion --- p.27 / Chapter 1.4.2.2 --- Gel Properties --- p.27 / Chapter 1.4.2.3 --- Mechanism of Gelation --- p.29 / Chapter 1.4.2.4 --- Gel Strength and Syneresis --- p.30 / Chapter 1.5 --- Physiological Effects --- p.32 / Chapter 1.5.1 --- Dietary Fibre --- p.32 / Chapter 1.5.2 --- Minerals --- p.32 / Chapter 1.6 --- Significance of the Present Study --- p.33 / Chapter CHAPTER TWO --- MATERIALS AND METHODS / Chapter 2.1 --- Seaweed Collection --- p.36 / Chapter 2.2 --- Sample Preparation --- p.36 / Chapter 2.3 --- Alginate Extraction --- p.38 / Chapter 2.3.1 --- Method A --- p.38 / Chapter 2.3.2 --- Method B --- p.38 / Chapter 2.3.3 --- Commercial Alginate --- p.39 / Chapter 2.4 --- Chemical Composition of Alginate --- p.41 / Chapter 2.4.1 --- Alginate Content --- p.41 / Chapter 2.4.2 --- Moisture Content --- p.41 / Chapter 2.4.3 --- Crude Protein Content --- p.41 / Chapter 2.4.4 --- Ash Content --- p.42 / Chapter 2.4.5 --- Monosaccharide Composition --- p.42 / Chapter 2.4.5.1 --- Acid Deploymerisation --- p.42 / Chapter 2.4.5.2 --- Neutral and Amino Sugar Derivatization --- p.42 / Chapter 2.4.5.3 --- Determination of Neutral Sugars by Gas Chromatography --- p.43 / Chapter 2.4.5.4 --- Uronic Acid Content --- p.44 / Chapter 2.4.6 --- Uronic Acid Block Composition --- p.44 / Chapter 2.4.6.1 --- "MG, MM and GG Block Determination" --- p.44 / Chapter 2.4.6.2 --- M/G Ratio Determination --- p.45 / Chapter 2.4.6.3 --- Phenol-Sulfuric Acid Method --- p.45 / Chapter 2.5 --- Physico-Chemical Properties of Alginate --- p.46 / Chapter 2.5.1 --- Viscosity --- p.46 / Chapter 2.5.1.1 --- Ostwald Viscometer --- p.46 / Chapter 2.5.1.2 --- Brookfield Viscometer --- p.47 / Chapter 2.5.2 --- Molecular Weight --- p.47 / Chapter 2.5.2.1 --- From Intrinsic Viscosity --- p.47 / Chapter 2.5.2.2 --- Gel Permeation Chromatography-Laser Light Scattering (GPC-LLS) --- p.48 / Chapter 2.6 --- Functional Properties of Alginate --- p.49 / Chapter 2.6.1 --- Emulsifying Activity (EA) and Emulsion Stability (ES) --- p.49 / Chapter 2.6.2 --- Gel Formation --- p.49 / Chapter 2.6.3 --- Gel Strength and Syneresis --- p.50 / Chapter 2.6.4 --- Application in Food ´ؤ Fruit Jelly --- p.52 / Chapter 2.7 --- Data Analysis --- p.53 / Chapter CHAPTER THREE --- RESULTS AND DISCUSSION / Chapter 3.1 --- Proximate Composition of Selected Seaweed --- p.54 / Chapter 3.1.1 --- Moisture Content --- p.54 / Chapter 3.1.2 --- Ash Content --- p.56 / Chapter 3.1.3 --- Crude Protein Content --- p.57 / Chapter 3.1.4 --- Carbohydrate Content --- p.58 / Chapter 3.2 --- Chemical Composition of Alginate Extracted from Two Different Methods --- p.58 / Chapter 3.2.1 --- Percentage Yield --- p.59 / Chapter 3.2.2 --- Alginate Content --- p.61 / Chapter 3.2.3 --- Moisture Content --- p.62 / Chapter 3.2.4 --- Ash Content --- p.62 / Chapter 3.2.5 --- Residual Protein Content --- p.63 / Chapter 3.2.6 --- Monosaccharide Composition of Alginate --- p.63 / Chapter 3.2.7 --- M/G Ratio --- p.66 / Chapter 3.2.8 --- Summary --- p.69 / Chapter 3.3 --- Comparative Studies of Physico-Chemical Composition of Alginate from Sargassum and Padina Species --- p.71 / Chapter 3.3.1 --- Block Composition and M/G Ratio --- p.71 / Chapter 3.3.2 --- Viscosity --- p.75 / Chapter 3.3.2.1 --- Intrinsic Viscosity ´ؤ Capillary Viscometer --- p.75 / Chapter 3.3.2.2 --- Solution Viscosity - Brookfield Viscometer --- p.79 / Chapter 3.3.2.2.1 --- Effect of Temperature --- p.79 / Chapter 3.3.2.2.2 --- Effect of Concentration --- p.81 / Chapter 3.3.2.2.3 --- Shear Thinning and Time Independent Effect --- p.82 / Chapter 3.3.3 --- Molecular Weight --- p.88 / Chapter 3.3.3.1 --- From Intrinsic Viscosity --- p.88 / Chapter 3.3.3.2 --- Gel Permeation Chromatograph-Laser Light Scattering (GPC-LLS) --- p.90 / Chapter 3.4 --- Comparative Studies of the Functional Properties of Extracted Alginate with Commercial Alginate --- p.93 / Chapter 3.4.1 --- Emulsifying Activity (EA) and Emulsifying Stability (ES) --- p.93 / Chapter 3.4.2 --- Gelling Properties --- p.95 / Chapter 3.4.2.1 --- Effect of Calcium Concentrations --- p.95 / Chapter 3.4.2.2 --- Gel Strength and Syneresis --- p.97 / Chapter 3.4.3 --- Application in Food --- p.99 / Chapter CHAPTER FOUR --- CONCLUSIONS --- p.103 / REFERENCES --- p.105 / RELATED PUBLICATION --- p.120

Renal failure uremia occurs when the kidneys fail to function properly. Despite being the main treatment, dialysis and other therapeutic approaches are not only associated with numerous long-term adverse complications often leading to morbidity and mortality events, but are also not affordable. Orally administrating Alginate-Poly-L-Lysine-Alginate microcapsules entrapping live yeast cells to treat renal failure uremia has not yet been investigated. In this thesis, the growth and microencapsulation of yeast were optimized. The efficacy of these microcapsules in removing unwanted electrolytes was tested in vitro in simulated gastro-intestinal media, in vitro in a column bioreactor and in vivo in an uremic rat model. Results showed that these novel microcapsules can not only maintain morphological stability and membrane integrity under gastro-intestinal environments and mechanical stresses, but also, preserve the viability of yeast. These microcapsules were successful in reducing urea concentrations while not harming the human GI tract's microbial flora.

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1983. / Extra t.p. with thesis statement inserted. Includes the author's seven published papers. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 9, 2009) Thesis advisor: Dr. Andrew D. Clarke. Includes bibliographical references.

Thèse (M.Sc.)--Université Laval, 2005. / Bibliogr. Publié aussi en version électronique.