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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Physicochemical properties and microencapsulation process development for fish oil using supercritical carbon dioxide

Seifried, Bernhard. January 2010 (has links)
Thesis (Ph.D.)--University of Alberta, 2010. / Title from PDF file main screen (viewed on July 29, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Bioresource and Food Engineering, Department of Agricultural, Food and Nutritional Science, University of Alberta. Includes bibliographical references.
12

Characterization of self-healing composite materials

Ford, Kevin J. January 2006 (has links)
Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xiv, 148 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 122-129).
13

Microencapsulação de oleoresina de cúrcuma (curcuma longa l.) em matrizes de gelatina, goma arábica e colágeno hidrolisado

Zuanon, Larissa Angélica Cirelli [UNESP] 03 July 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:24:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-07-03Bitstream added on 2014-06-13T20:13:00Z : No. of bitstreams: 1 zuanon_lac_me_sjrp.pdf: 872314 bytes, checksum: e0f0fa372249d8d12c8aa3dadec1e0cf (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A cúrcuma (Curcuma longa L.) é originária do sudeste asiático, pertencente à família das Zingiberaceae. Depois de secos, os rizomas da cúrcuma podem ser submetidos a processos de extração, dando origem a óleos essenciais ou ao seu principal pigmento, a curcumina, um corante amarelo usado na indústria de alimentos para conferir cor e sabor. A curcumina é solúvel em etanol e outros solventes orgânicos, porém é insolúvel em meio aquoso, além de apresentar instabilidade em relação a diversos fatores físicos e ambientais, como à luz, ao pH e às altas temperaturas. Com o duplo objetivo de aumentar a estabilidade do pigmento e de suas propriedades funcionais, seja durante seu armazenamento ou durante a vida de prateleira dos alimentos nos quais seja utilizado como ingrediente, bem como facilitar sua utilização em meios aquosos, neste trabalho foi estudada a microencapsulação de oleoresina de cúrcuma utilizando misturas de gelatina / goma arábica e gelatina / colágeno hidrolisado como matrizes encapsulantes e empregando como métodos de secagem a liofilização e a secagem por aspersão (spray drying). Foram determinadas as proporções de agente encapsulante e oleoresina mais adequadas ao processo e as microcápsulas foram analisadas em relação à eficiência de encapsulação, morfologia, solubilidade e estabilidade à luz. Foram produzidos doze sistemas por coacervação complexa para cápsulas de gelatina / goma arábica, cuja eficiência de encapsulação variou entre 49 e 73 %, sendo classificados os sistemas com 2,5% de material de parede e 100 % de recheio (Sistema 4) e com 5,0 % de material de parede e 50% de recheio (Sistema 6) para os testes de estabilidade à luz, no qual o Sistema 4 foi o mais estável. Nos seis sistemas produzidos para microcápsulas de gelatina / colágeno hidrolisado os valores... / Turmeric (Curcuma longa L.) is indigenous to Southeast Asia, belonging to the family Zingiberaceae. After drying, the rhizomes of turmeric may be subjected to extraction processes, resulting in essential oils or their main pigment, curcumin, a yellow dye used in the food industry to impart color and flavor. Curcumin is soluble in ethanol and other organic solvents but insoluble in aqueous medium, in addition to be unstable with respect to various physical and environmental factors such as light, pH and high temperatures. With the dual aim of increasing the stability of the pigment and its functional properties, either during storage or during shelf life of foods in which it is used as an ingredient, and to facilitate the use in aqueous medium, it was studied the microencapsulation of turmeric oleoresin using mixtures of gelatin / arabic gum and gelatin / hydrolyzed collagen as arrays employing as encapsulants and the drying methods freeze and spray drying. Proportions of oleoresin and encapsulating agent more suited to the process were determined and the microcapsules were analyzed for the encapsulation efficiency, morphology, solubility and stability to light. Twelve systems were produced by complex coacervation to capsules of gelatin / arabic gum, whose encapsulation efficiency ranged from 49 to 73 %. The systems with 2.5 % of wall material and 100 % of filling (System 4) and the one with 5.0 % of wall material and 50 % of filling (System 6) were classified for the tests of stability to light, in which the System 4 was more stable. In the six systems to produce microcapsules with gelatin / hydrolyzed collagen the encapsulation efficiency values ranged from 17 to 57 %, and which contained 30% total solids (28 % of hydrolyzed collagen and 2 % of gelatin) - System B - followed to test of stability to light, together ... (Complete abstract click electronic access below)
14

Microencapsulação de oleoresina de cúrcuma (curcuma longa l.) em matrizes de gelatina, goma arábica e colágeno hidrolisado /

Zuanon Sardella, Larissa Angélica Cirelli. January 2012 (has links)
Orientador: Vânia Regina Nicoletti Telis / Coorientador: Cássia Roberta Malacrida / Banca: Patrícia de Carvalho Damy Benedetti / Banca: Renato Alexandre Ferreira Cabral / Resumo: A cúrcuma (Curcuma longa L.) é originária do sudeste asiático, pertencente à família das Zingiberaceae. Depois de secos, os rizomas da cúrcuma podem ser submetidos a processos de extração, dando origem a óleos essenciais ou ao seu principal pigmento, a curcumina, um corante amarelo usado na indústria de alimentos para conferir cor e sabor. A curcumina é solúvel em etanol e outros solventes orgânicos, porém é insolúvel em meio aquoso, além de apresentar instabilidade em relação a diversos fatores físicos e ambientais, como à luz, ao pH e às altas temperaturas. Com o duplo objetivo de aumentar a estabilidade do pigmento e de suas propriedades funcionais, seja durante seu armazenamento ou durante a vida de prateleira dos alimentos nos quais seja utilizado como ingrediente, bem como facilitar sua utilização em meios aquosos, neste trabalho foi estudada a microencapsulação de oleoresina de cúrcuma utilizando misturas de gelatina / goma arábica e gelatina / colágeno hidrolisado como matrizes encapsulantes e empregando como métodos de secagem a liofilização e a secagem por aspersão (spray drying). Foram determinadas as proporções de agente encapsulante e oleoresina mais adequadas ao processo e as microcápsulas foram analisadas em relação à eficiência de encapsulação, morfologia, solubilidade e estabilidade à luz. Foram produzidos doze sistemas por coacervação complexa para cápsulas de gelatina / goma arábica, cuja eficiência de encapsulação variou entre 49 e 73 %, sendo classificados os sistemas com 2,5% de material de parede e 100 % de recheio (Sistema 4) e com 5,0 % de material de parede e 50% de recheio (Sistema 6) para os testes de estabilidade à luz, no qual o Sistema 4 foi o mais estável. Nos seis sistemas produzidos para microcápsulas de gelatina / colágeno hidrolisado os valores... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Turmeric (Curcuma longa L.) is indigenous to Southeast Asia, belonging to the family Zingiberaceae. After drying, the rhizomes of turmeric may be subjected to extraction processes, resulting in essential oils or their main pigment, curcumin, a yellow dye used in the food industry to impart color and flavor. Curcumin is soluble in ethanol and other organic solvents but insoluble in aqueous medium, in addition to be unstable with respect to various physical and environmental factors such as light, pH and high temperatures. With the dual aim of increasing the stability of the pigment and its functional properties, either during storage or during shelf life of foods in which it is used as an ingredient, and to facilitate the use in aqueous medium, it was studied the microencapsulation of turmeric oleoresin using mixtures of gelatin / arabic gum and gelatin / hydrolyzed collagen as arrays employing as encapsulants and the drying methods freeze and spray drying. Proportions of oleoresin and encapsulating agent more suited to the process were determined and the microcapsules were analyzed for the encapsulation efficiency, morphology, solubility and stability to light. Twelve systems were produced by complex coacervation to capsules of gelatin / arabic gum, whose encapsulation efficiency ranged from 49 to 73 %. The systems with 2.5 % of wall material and 100 % of filling (System 4) and the one with 5.0 % of wall material and 50 % of filling (System 6) were classified for the tests of stability to light, in which the System 4 was more stable. In the six systems to produce microcapsules with gelatin / hydrolyzed collagen the encapsulation efficiency values ranged from 17 to 57 %, and which contained 30% total solids (28 % of hydrolyzed collagen and 2 % of gelatin) - System B - followed to test of stability to light, together ... (Complete abstract click electronic access below) / Mestre
15

Desenvolvimento de microcápsulas de edulcorantes produzidas por dupla emulsão seguida de coacervação complexa e estudo de sua funcionalidade em gomas de mascar / Development of sweeteners microcapsules produced by double emulsion followed by complex coacervation and study of their functionality un chewing gum

Rocha-Selmi, Glaucia Aguiar, 1984- 24 August 2018 (has links)
Orientadores: Helena Maria Andre Bolini, Carmen Silvia Favaro Trindade / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-24T11:28:31Z (GMT). No. of bitstreams: 1 Rocha-Selmi_GlauciaAguiar_D.pdf: 1376353 bytes, checksum: a98171976932c5f1d1e51409508be9f5 (MD5) Previous issue date: 2014 / Resumo: Em todo o mundo, tem-se observado o aumento do interesse da população em ingerir produtos isentos de açúcar e com menor teor calórico. Esse interesse tem impulsionado o mercado dos produtos chamados diet/light e as gomas de mascar desempenham importante papel neste setor. Os edulcorantes utilizados nesse segmento podem ser microencapsulados, com o objetivo de reduzir a higroscopicidade desses compostos e prolongar a sensação de doçura. A microencapsulação é uma tecnologia que vem se mostrando viável para diversas aplicações industriais. O prolongamento do gosto doce é bastante desejado em alguns produtos, especialmente as gomas de mascar, que permanecem um período maior na boca antes da ingestão. Nesse contexto, os objetivos deste trabalho foram desenvolver e caracterizar microcápsulas com diferentes tipos de edulcorantes, aplicá-las em gomas de mascar e determinar o perfil tempo-intensidade de doçura, além da aceitação dos produtos em relação à aparência, aroma, sabor, textura e impressão global. Mesmo sendo compostos hidrofílicos, foi possível encapsular os edulcorantes aspartame, sucralose e estévia por meio da adição da técnica de dupla emulsão ao processo de encapsulação por coacervação complexa. As microcápsulas formadas eram esféricas, multinucleadas e apresentaram baixos valores de solubilidade e higroscopicidade. As gomas de mascar produzidas com edulcorante microencapsulado apresentaram um perfil de liberação do gosto doce mais duradouro em relação às amostras produzidas com edulcorante na forma livre, sem perda da aceitação pelos consumidores, o que indica a potencialidade do uso desse tipo de microcápsulas em gomas de mascar visando aumentar o tempo de duração do gosto doce / Abstract: In recent years, the interest of the population in consuming lower-calorie sugar-free products has grown. This interest has driven the market of light and diet products, and chewing gums play an important role in this sector. Microencapsulation is a technology that has proven viable for several industrial applications. With regard to sweeteners, the process may reduce the hygroscopicity of such compounds and extend the sensation of sweetness. Extending the sweet taste is quite interesting for some products, especially chewing gums, which remain a longer period in the mouth during consumption. In this context, this study aimed at developing and characterizing microcapsules containing different types of sweeteners, applying the microcapsules in chewing gum and determining the time-intensity sweetness profile and acceptance of products, concerning the parameters appearance, aroma, flavor, texture and overall impression. Although sweeteners are hydrophilic compounds, it was possible to encapsulate aspartame, sucralose and stevia using double emulsion stage prior to complex coacervation process. The microcapsules formed were spherical, multinucleated and exhibited low values of solubility and hygroscopicity. The chewing gum produced with microencapsulated sweetener showed a more prolonged sweetness release profile than the samples containing sweetener in free form, without affecting consumer acceptance, indicating the potential use of such microcapsules in chewing gum aimed at extending sweetness duration / Doutorado / Consumo e Qualidade de Alimentos / Doutora em Alimentos e Nutrição
16

Production of drugs in small particle form /

Chen, Chih-Ming James, January 1981 (has links)
No description available.
17

Microencapsulation pour l'autoréparation / Self-healing microencapsulation

Caserta, Laura 28 October 2011 (has links)
Un matériau qui se répare tout seul. Une fissure ou une rayure qui se rebouche elle-même après un impact, comme une blessure pour un être vivant. Le concept d’autoréparation ainsi décrit n’est plus une idée purement fantaisiste issue de l’imagination fertile des chercheurs. De récents travaux prouvent le contraire. Catalyse a choisi de mettre au point un processus d’autoréparation par l’intégration de microparticules contenant un principe actif liquide, libéré lors son l’éclatement. Ce liquide, un monomère, va alors polymériser, rebouchant ainsi la fissure et empêchant sa propagation.L’innovation de Catalyse a été d’imaginer une formulation autoréparante capable de polymériser directement au contact du milieu extérieur. Les éléments alors mis à disposition par l’environnement peuvent être la lumière (rayonnements UV ou visibles), l’oxygène, ou l’humidité. Les monomères envisagés pour l’encapsulation sont alors respectivement un acrylate, TMPTA, ou une époxy (mélangés avec un photoamorceur adapté), l’huile de lin (siccative) et un isocyanate trimère de l’hexamétylène diisocyanate. L’encapsulation des ces quatre composés est étudiée en parallèle et les travaux réalisés sont explicités dans les chapitres 2, 3 et 4 de ce document. Le TMPTA et l’huile de lin sont encapsulés par le procédé sol-gel, l’époxy et l’isocyanate, par polycondensation interfaciale. Les résultats obtenus sont variables d’un monomère à l’autre, mais dans l’ensemble, les résultats sont concluants et montrent d’une part, qu’il est possible d’obtenir des particules contenant un taux de principe actif intéressant et stables dans le temps, et d’autre part que suite à l’éclatement desdites capsules, le monomère polymérise, assurant ainsi le processus d’autoréparation. / A material that could repair itself, a crack that can heal itself after an impact, like a wound on the body. The concept of self-healing described is not science fiction created by the crazy imagination of researchers. Recent studies show otherwise. The French company CATALYSE has developed a process of self-healing through the integration of microparticles containing an active liquid ingredient that is released during a crack in the material. The liquid monomer fills the crack, polymerizes and prevents further spread. The innovation of CATALYSE was to imagine a self-repairing formula, which polymerizes when exposed to the outside of the self-contained environment. This includes light (UV or visible rays), oxygen or humidity. The corresponding monomers to be encapsulated are respectively an acrylate (for example TMPTA), an epoxy (mixed with an adapted photoinitiator), linseed oil or diisocyanate (for example an isocyanine trimer or hexamethylene diisocyanate). The encapsulations of these four compounds were studied in parallel and the results are explained in chapters 2, 3 and 4 of this document. The TMPTA and linseed oil are both encapsulated by the sol-gel process, the epoxy and isocyanate, by interfacial polycondensation. The results vary from one monomer to another but the overall results are conclusive. They show that it is possible to obtain a high percentage of the active ingredient and that the particles stay stable over time. Following the bursting of such capsules, the monomer polymerizes and ensures the self-healing process.
18

Conception d'étiquettes autoadhésives par microencapsulation d'adhésif / Autoadhesive labels design by adhesive microencapsulation

Abderrahmen, Robin 12 December 2012 (has links)
Le but de ce projet est de concevoir un nouveau type d'étiquette ‘écologique', n'utilisant pas de dorsale siliconé. Ainsi, la couche d'adhésif est remplacée par une couche de microcapsules d'adhésif. Ces microcapsules doivent avoir une paroi suffisamment étanche et résistante pour envelopper l'adhésif et ne pas se rompre lors des étapes de fabrication du produit. Par contre, elles doivent céder sous l'effet d'une pression et libérer l'adhésif au moment de leur utilisation. Dans un premier temps, 3 adhésifs en émulsion aqueuse ont été caractérisés en vue de leur microencapsulation. Par la suite, un adhésif a été sélectionné et encapsulé par coacervation (avec des biomatériaux comme carapace) et par polymérisation in situ aminoplaste. Ensuite, 2 autres procédés d'encapsulation d'adhésif réalisés au LAGEP (le spray-drying et le spray-cooling) ont été comparés avec les 2 techniques précédentes. Les capsules produites par spray-cooling, les plus adhésives, ont permis la formulation d'un bain d'enduction en vue d'un couchage des capsules à l'aide d'une barre de Meyer, et par procédé sérigraphique. La compatibilité de ces microcapsules avec le procédé de fabrication d'une étiquette autoadhésive classique, sur une rotative d'impression flexographique, a été montrée. Les caractéristiques finales du produit ainsi fabriqué (adhésion, pression d'application) ont été comparées avec celles de différents produits autoadhésifs industriels (étiquette, enveloppe et timbre). / The main objective of this investigation is to prepare innovative silicone liner-free labels. It can be achieved by the adhesive ‘self protection', thanks to its incorporation into microcapsules. This allows the preparation of ‘dry labels' gluing under the application of a pressure, which induces the rupture of the microcapsules, thus releasing the core material, a pressure sensitive adhesive. The first step was to analyse 3 water-based PSA in view of their encapsulation. Then, the most suitable adhesive was microencapsulated by coacervation (using biopolymer as shell) and by in situ polymerisation. Two other encapsulation processes (spray-cooling and spray-drying), were also carried out at the LAGEP and were compared with the 2 former processes. Coating colour formulations were prepared with spray-cooling microcapsules (the most adhesive ones). Coating trials were carried out with a Meyer rod, and by screen printing. Compatibility between microcapsules and the label making process, using a flexographic printing press, was determined. Finally, the mains characteristics of the prepared innovative products (adhesion, application pressure) were compared to industrial self-adhesive homologues, and found that they could be suitable for the preparation of silicon liner-free envelops and stamps.
19

Microencapsulation of water-soluble substances for delivery to marine bivalves

Buchal, Michael A. 12 December 1994 (has links)
A new method for encapsulating low-molecular weight, water-soluble substances in lipid-walled microcapsules (LWMs) for delivery to marine bivalves was developed, characterized, and tested. LWMs produced by a spray technique (spray microcapsules, SMs) were demonstrated to encapsulate both aqueous (polymeric dye or oxytetracycline hydrochloride) and particulate (riboflavin) core materials within a capsule wall composed of triacylglycerides. Core materials were most effectively delivered in a capsule wall composed of tripalmitin. Addition of lower melting point lipids to soften the capsule wall significantly reduced (up to a nine-fold reduction) delivery of aqueous core materials, but did not significantly affect particulate riboflavin delivery. The composition of the capsule wall was demonstrated to affect the digestibility of LWMs. Addition of 40% w/w fish oil to the tripalmitin wall was required for Manila clam spat (Tapes philippinarum) enzymatically digest LWMs (convert triaclyglycerides to free fatty acids). Delivery of aqueous and particulate core materials by microcapsules was assessed by feeding clams LWMs containing an aqueous core of polymeric dye or a particulate core of oxytetracycline hemicalcium salt (OTC.HEM). The physical appearance and absence of core material in capsules observed in clam fecal strands suggested release and delivery of core materials in the clam's digestive system. Optimal methods for encapsulating and storing oxytetracycline were assessed. Oxytetracycline hydrochloride was most efficiently encapsulated (3.2 mg core/ 100 mg lipid) and retained (30%) as an aqueous core in LWMs produced by a double-emulsion process (double-emulsion microcapsules, DEMs). OTC.HEM was most efficiently encapsulated (7.4 mg core/l00 mg lipid) and retained (66% of initial encapsulated core material remained after 24 hours suspension in seawater) as a particulate in SMs. SMs containing OTC.HEM were most stable in storage, retaining 86% of their core after 5 weeks of storage as a wet paste. Freeze-drying of SMs containing particulate OTC.HEM increased initial leakage losses of core material, but did not the affect the stability of capsules during long-term storage. Freeze-drying of DEMs containing aqueous OTC.HCl also increased initial leakage loses of core material, but improved the stability of DEMs during long-term storage. / Graduation date: 1995
20

Alginate strings and their applications in spinal cord regeneration /

Kanakasabai, Saravanan. Wheatley, Margaret A. January 2007 (has links)
Thesis (Ph. D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 111-123).

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