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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.
91

Produção e caracterização microestrutural de sistemas lípidicos sólidos micro e nanoparticulados utilizados na encapsulação de beta-caroteno / Production and microestrutural caracterization of solid lipids systems micro and nanoparticulate used for beta-carotene encapsulation

Graziela Veiga de Lara Gomes 14 March 2011 (has links)
O benefício do consumo de compostos bioativos, como os carotenóides, tem sido amplamente demonstrado pela literatura científica. No entanto, alguns destes bioativos (como os carotenos), devido à sua hidrofobicidade, apresentam dificuldades para serem incorporados em formulações alimentícias aquosas, além de serem, dependendo da matriz alimentícia na qual estão inseridos, dificilmente absorvidos no tratogastrointestinal - ou seja, possuem limitada biodisponibilidade. Tais problemas podem ser contornados através da micro e da nanoencapsulação. O presente trabalho de Mestrado teve como objetivo utilizar a triestearina e o ácido esteárico para a encapsulação do beta-caroteno em micro e nanopartículas lipídicas sólidas, a caracterização físico-química das estruturas formadas e a avaliação da estabilidade química e microestrutural das mesmas. Nos sistemas microparticulados de ácido esteárico (AE) foi utilizado como tensoativo o polisorbato 80 e foram produzidos com 4 e 6% de lipídio, na ausência e na presença de alfa-tocoferol, e todos se mostram extremamente estáveis em relação à distribuição do tamanho médio das partículas, mas somente as partículas que continham alfa-tocoferol conseguiram preservar o beta-caroteno ao longo do período de 7 meses de armazenagem. No caso das micropartículas de triestearina também foram produzidos sistema com 4 e 6% de lipídio total, e a presença do hidrocolóide goma xantana foi essencial para evitar a floculação e permitir a estabilidade do sistema, e foram testadas formulações contendo misturas de tensoativos fosfatidilcolina de soja e polisorbato 60 e fosfatidilcolina de soja e polisorbato 20. Dentre tais sistemas, somente as micropartículas sólidas estabilizadas com polisorbato 60 se mostraram estáveis em relação ao tamanho médio das partículas, e o sistema com menor quantidade de lipídio manteve-se resistente à floculação até o 4º mês de estocagem. Sistemas nanoparticulados foram produzidos com 6% de lipídio total, testando-se uma e duas passagens no homogeneizador à alta pressão. Os dados obtidos indicaram que as nanopartículas lipídicas de AE não diferiram em relação à distribuição de tamanho, mas apresentaram aumento do diâmetro de partícula ao longo do tempo de estocagem. Por sua vez, para as nanopartículas de triestearina os sistemas (tanto com uma quanto com duas passagens no homogeneizador a alta pressão) se mostraram estáveis até cerca de dois meses de armazenagem, em termos de diâmetro médio de partícula, sendo que a distribuição de tamanho se mostrou mais homogênea para o sistema com duas passagens. A microestrutura de todos os sistemas foi avaliada por difratometria de raio-X (DRX) e calorimetria diferencial de varredura (DSC), e a quantidade de beta-caroteno preservada ao longo do tempo foi monitorada espectofometricamente e por colorimetria instrumental. De maneira geral, os sistemas microparticulados se mostraram melhores do que os nanoparticulados, tanto do ponto de vista de estabilidade da estrutura quanto da preservação do beta-caroteno. / The benefits from the consumption of bioactive compounds, like carotenoids, have been widely demonstrated for scientific literature. However, some of this compounds (like carotenes), due totheir hydrophobicity, are difficult to be incorporated in aqueous food formulations, and, depending on the food matrices where they are introduced, are hardly absorbed in the gastrointestinal tract - in order words, they present limited bioavailability. These problems can be overcome by micro and nanoencapsulation. In this context, the objective of this study was to investigate the temporal stability of beta-carotene encapsulated in solid lipid micro and nano particles produced with a mixture of stearic acid or tristearin and sunflower oil, monitoring the microstructure of the systems by X-ray diffractometry, differential scanning calorimetry, zeta potential and particle size measurements, and try to link the preservation of beta-carotene with microstructural considerations. The surfactant used for the stearic acid microparticulate systems was polysorbate 80 and formulations with 4 and 6% of total lipid were produced, in the absence and presence of alpha-tocopherol, and all systems showed high stability in terms of average particle diameter and size distribution, but only the particles containing alpha-tocopherol preserved the content of beta-carotene during the storage period of 7 months In the case of the tristearin microparticles the presence of a hydrocolloid (xanthan gum) was essential for avoid flocculation and improves the system stability, and formulations containing mixtures of surfactants (soybean phosphatidylcholine and polysorbate 60 and phosphatidylcholine and polysorbate 20) were tested. Among such systems, only the solidmicroparticles stabilized with phosphatidylcholine and polysorbate 60 showed stability in terms of average particle diameter and size distribution, and the system with less concentration of solid lipid did not show significant destabilization until the 4th month of storage. As for the nanoparticulated systems, formulations with 6% of total lipid were produced, testing one and two passages in high pressure homogenizer. Our results indicated the stearic acid solid nanoparticles did not exhibitalterations of size distribution, but average particle diameter increased along the time. On the other hand, the triestearin nanoparticles (both with one and two passage in high pressure homogeneizer) showed stability until two months of storage, in terms of average particle diameter, and the size distribution demonstrated to be more homogeneous for the systems submitted to two passages. As an overall conclusion, the microparticulated systems seemed to be more stable than the nanoparticulated ones, from the point of view of structure stability as well as in terms of beta-carotene preservation of beta-carotene.
92

Adaptability and encapsulation in dynamically typed languages : taming reflection and extension methods / Adaptabilité et encapsulation dans les langages dynamiquement typés : contrôler la réflexion et les méthodes d’extension

Teruel, Camille 21 January 2016 (has links)
Les utilisateurs s'attendent à ce que les logiciels soient à la fois continuellement disponibles et mis-à-jour à la volée. L'introduction de nouvelles fonctionnalités et l'intégration de correctifs ne doit pas perturber la bonne marche d'une application. Les développeurs bénéficient aussi de la modification dynamique des logiciels en adaptant le code à de nouvelle situations ou bien an exécutant des analyses dynamiques à des fins de monitorage, de déboguage et d’optimisation. Les langages de programmation doivent donc fournir aux développeurs des mécanismes qui améliorent l'adaptabilité logicielle. Dans le même temps, l'augmentation de la taille et de la complexité des logiciels requièrent des applications faites de nombreux composants développés par différents groupes. Dans ce contexte chaque composant doit être convenablement protégé des autres. Les langages de programmation doivent donc aussi fournir des mécanismes qui améliorent l'encapsulation. Le besoin de supporter des adaptations dynamiques d'un côté, et le besoin d'avoir des composants convenablement confinés d'un autre, poussent la conception des langages de programmation dans deux directions opposées: soit plus de flexibilité, soit plus de contrôle. Cette dissertation étudie cette tension dans le contexte des langages orientée-objet dynamiquement typés via deux mécanismes qui promeuvent l'adaptabilité logicielle: la réflexion et les méthodes d’extension. Pour chacun de ces mécanismes, nous démontrons leur utilité, leurs effets néfastes sur l'encapsulation et proposons des solutions qui conservent leurs forces tout en maintenant l'encapsulation. / Users expect modern software to be both continually available and updated on the fly. Introduction of new features and integration of bug fixes should not trouble the smooth running of an application. Developers also benefit from dynamic modifications of software by adapting code to new unanticipated situations or by running dynamic analyses to get feedback about the behavior of running applications for monitoring, debugging and optimization purposes. Programming languages should thus provides developers with mechanisms that improve software adaptability. At the same time, the increasing size and complexity of software call for applications made up of many interacting components developed by different parties. In this context, each component needs to be properly protected from other ones. Programming languages should thus provide developers with mechanisms that improve encapsulation. The need for dynamic adaptations on the one hand and the need for properly confined components on the other hand pulls programming language design in two opposite directions: either more flexi-bility or more control.This dissertation studies this tension in the context of dynamically-typed object-oriented languages with two language mechanisms that promote software adaptability: reflection and extension meth-ods. For both mechanisms, we demonstrate their usefulness, their harmful effect on encapsulation and propose solutions to retain their power while maintaining encapsulation.
93

Engineering bacteriophage encapsulation processes to improve stability and controlled release using pH responsive formulations

Vinner, Gurinder K. January 2018 (has links)
Enteric pathogens form a large part of infectious diseases which contribute to a bulk of the healthcare costs. Enteric infections are usually contracted via the faecal-oral route or through contact with contaminated surfaces. Treatment by antibiotics is becoming increasingly ineffective due to the growing number of antibiotic resistant strains. Anti-microbial resistance poses a serious threat to the future of healthcare worldwide and necessitates the search for alternate forms of therapy. Bacteriophages (phages), are viruses which specifically infect and lyse bacteria. To introduce phages as a viable form of therapy, route of administration needs to be considered carefully. Model phages with broad host ranges are ideal for therapy however oral delivery to the lower gastro-intestinal (GI) poses several challenges. The acidic stomach environment can be detrimental to phages, rendering them inactive during passage. To overcome this challenge and improve the stability of phage during encapsulation and storage, this PhD research has been conducted. pH responsive polymers, Eudragit and alginate were used to develop composite microparticles which protected phage from acidic pH (pH 1-3). A novel method of acidifying oil was developed for crosslinking droplets in vitro to avoid the use of harsh solvent systems that can cause phage inactivation. Platform microfluidic technology was employed for phage encapsulation for the first time. Monodispersed droplets and particles were produced, offering fine-tuning of droplet diameter to tailor the release and pH protection of encapsulated phage. Process scale-up was attempted using membrane emulsification (ME) to produce larger volumes of encapsulated phage. In vitro and in-situ models investigated the efficacy of encapsulated phage-bacterial killing. Industrial scale method of spray drying, and electrospinning were also used to demonstrate the versatility of the formulation. Tableting dry powder phage, showed an effective method for producing solid dosage forms for therapy. Additionally, electrospun phage fibres also showed the potential use of pH responsive formulations in addressing wound infections. Improvement in encapsulated phage storage stability was observed with the addition of trehalose in the formulation. This research underpins the need for testing phage encapsulation for site-specific delivery and offers insight into the potential use of commercially available technologies.
94

Produção e caracterização microestrutural de sistemas lípidicos sólidos micro e nanoparticulados utilizados na encapsulação de beta-caroteno / Production and microestrutural caracterization of solid lipids systems micro and nanoparticulate used for beta-carotene encapsulation

Gomes, Graziela Veiga de Lara 14 March 2011 (has links)
O benefício do consumo de compostos bioativos, como os carotenóides, tem sido amplamente demonstrado pela literatura científica. No entanto, alguns destes bioativos (como os carotenos), devido à sua hidrofobicidade, apresentam dificuldades para serem incorporados em formulações alimentícias aquosas, além de serem, dependendo da matriz alimentícia na qual estão inseridos, dificilmente absorvidos no tratogastrointestinal - ou seja, possuem limitada biodisponibilidade. Tais problemas podem ser contornados através da micro e da nanoencapsulação. O presente trabalho de Mestrado teve como objetivo utilizar a triestearina e o ácido esteárico para a encapsulação do beta-caroteno em micro e nanopartículas lipídicas sólidas, a caracterização físico-química das estruturas formadas e a avaliação da estabilidade química e microestrutural das mesmas. Nos sistemas microparticulados de ácido esteárico (AE) foi utilizado como tensoativo o polisorbato 80 e foram produzidos com 4 e 6% de lipídio, na ausência e na presença de alfa-tocoferol, e todos se mostram extremamente estáveis em relação à distribuição do tamanho médio das partículas, mas somente as partículas que continham alfa-tocoferol conseguiram preservar o beta-caroteno ao longo do período de 7 meses de armazenagem. No caso das micropartículas de triestearina também foram produzidos sistema com 4 e 6% de lipídio total, e a presença do hidrocolóide goma xantana foi essencial para evitar a floculação e permitir a estabilidade do sistema, e foram testadas formulações contendo misturas de tensoativos fosfatidilcolina de soja e polisorbato 60 e fosfatidilcolina de soja e polisorbato 20. Dentre tais sistemas, somente as micropartículas sólidas estabilizadas com polisorbato 60 se mostraram estáveis em relação ao tamanho médio das partículas, e o sistema com menor quantidade de lipídio manteve-se resistente à floculação até o 4º mês de estocagem. Sistemas nanoparticulados foram produzidos com 6% de lipídio total, testando-se uma e duas passagens no homogeneizador à alta pressão. Os dados obtidos indicaram que as nanopartículas lipídicas de AE não diferiram em relação à distribuição de tamanho, mas apresentaram aumento do diâmetro de partícula ao longo do tempo de estocagem. Por sua vez, para as nanopartículas de triestearina os sistemas (tanto com uma quanto com duas passagens no homogeneizador a alta pressão) se mostraram estáveis até cerca de dois meses de armazenagem, em termos de diâmetro médio de partícula, sendo que a distribuição de tamanho se mostrou mais homogênea para o sistema com duas passagens. A microestrutura de todos os sistemas foi avaliada por difratometria de raio-X (DRX) e calorimetria diferencial de varredura (DSC), e a quantidade de beta-caroteno preservada ao longo do tempo foi monitorada espectofometricamente e por colorimetria instrumental. De maneira geral, os sistemas microparticulados se mostraram melhores do que os nanoparticulados, tanto do ponto de vista de estabilidade da estrutura quanto da preservação do beta-caroteno. / The benefits from the consumption of bioactive compounds, like carotenoids, have been widely demonstrated for scientific literature. However, some of this compounds (like carotenes), due totheir hydrophobicity, are difficult to be incorporated in aqueous food formulations, and, depending on the food matrices where they are introduced, are hardly absorbed in the gastrointestinal tract - in order words, they present limited bioavailability. These problems can be overcome by micro and nanoencapsulation. In this context, the objective of this study was to investigate the temporal stability of beta-carotene encapsulated in solid lipid micro and nano particles produced with a mixture of stearic acid or tristearin and sunflower oil, monitoring the microstructure of the systems by X-ray diffractometry, differential scanning calorimetry, zeta potential and particle size measurements, and try to link the preservation of beta-carotene with microstructural considerations. The surfactant used for the stearic acid microparticulate systems was polysorbate 80 and formulations with 4 and 6% of total lipid were produced, in the absence and presence of alpha-tocopherol, and all systems showed high stability in terms of average particle diameter and size distribution, but only the particles containing alpha-tocopherol preserved the content of beta-carotene during the storage period of 7 months In the case of the tristearin microparticles the presence of a hydrocolloid (xanthan gum) was essential for avoid flocculation and improves the system stability, and formulations containing mixtures of surfactants (soybean phosphatidylcholine and polysorbate 60 and phosphatidylcholine and polysorbate 20) were tested. Among such systems, only the solidmicroparticles stabilized with phosphatidylcholine and polysorbate 60 showed stability in terms of average particle diameter and size distribution, and the system with less concentration of solid lipid did not show significant destabilization until the 4th month of storage. As for the nanoparticulated systems, formulations with 6% of total lipid were produced, testing one and two passages in high pressure homogenizer. Our results indicated the stearic acid solid nanoparticles did not exhibitalterations of size distribution, but average particle diameter increased along the time. On the other hand, the triestearin nanoparticles (both with one and two passage in high pressure homogeneizer) showed stability until two months of storage, in terms of average particle diameter, and the size distribution demonstrated to be more homogeneous for the systems submitted to two passages. As an overall conclusion, the microparticulated systems seemed to be more stable than the nanoparticulated ones, from the point of view of structure stability as well as in terms of beta-carotene preservation of beta-carotene.
95

Encapsulation de molécules organiques au sein de silices mésoporeuses / Encapsulation of organic molecules in mesoporous silica

Bongur, Raphaël 04 November 2010 (has links)
L’objectif de cette thèse est de développer un concept inédit permettant l’utilisation de silices mésoporeuses pour encapsuler des principes actifs cosmétiques de façon permanente, ce qui permet d’améliorer leur tolérance cutanée, d’optimiser leur stabilité à la lumière tout en préservant leur efficacité et de faciliter leur formulation au sein de produits cosmétiques. Pour cela, la voie consistant à encapsuler des filtres UV à usage cosmétique au sein de silices mésoporeuses de type MCM-41 de façon in-situ a été choisie car elle semblait la plus propice à l’encapsulation d’une grande quantité de principes actifs de façon permanente. Deux filtres UV ont été étudiés un lipophile, nommé Parsol MCX, et un hydrophile, appelé Parsol HS. Pour l’ensemble des principes actifs étudiés, un taux d’encapsulation approprié a été obtenu et les caractérisations, effectuées notamment par RMN du solide, ont permis de montrer que l’encapsulation est effective au sein des pores ce qui, couplé à la bonne stabilité de l’encapsulation dans le cas de l’actifs hydrophile, garantit un contact minimum entre l’actif et la peau du consommateur. En revanche, un relargage important de filtre UV lipophile a été constaté. Il a été établi que les propriétés physico-chimiques des matériaux diffèrent significativement suivant que les principes actifs encapsulés soient lipophiles ou hydrophiles. Dans tous les cas, l’organisation poreuse, l’ordre structural et la morphologie des particules contenant des principes actifs varient significativement par rapport aux silices mésoporeuses de référence de type MCM-41, synthétisées sans principe actif. La présence de principe actif au sein du milieu réactionnel a donc une influence sur la structure et la texture des matériaux obtenus, ce qui est dû aux interactions entre les molécules de principe actif, les espèces silicate et les molécules de tensioactif au sein du milieu réactionnel. / The objective of this thesis is to develop a new concept that consists to permanently encapsulate cosmetic active ingredients into mesoporous silica. The encapsulation of these active molecules improves their skin tolerance, optimizes their light stability while preserving their effectiveness and facilitates their formulation in cosmetic products. Thus, UV filters have been encapsulated in MCM-41 type mesoporous silica by using in-situ route because it seemed the most efficient route to achieve permanently encapsulation of large quantities of active. Two UV filters have been studied. One is lipophilic (Parsol MCX) and the other is a hydrophilic (Parsol HS). For all the active molecules studied, an appropriate encapsulation rate was obtained and the characterizations, particularly these performed by solid-state NMR, have shown that the encapsulation is effective within the pores which, coupled with the good stability of encapsulation in the case of hydrophilic actives, ensures minimal contact between the active and the consumer's skin. In contrast, a significant release of lipophilic UV filter was found. It was established that the physico-chemical properties of the synthesized materials differ significantly according to the lipophilic or hydrophilic nature of the encapsulated molecules. In all cases, the porous organization, the structural order and the morphology of the particles containing active ingredients vary significantly compared to the reference MCM-41 type mesoporous silica, synthesized without active ingredient. Thus, the presence of the active ingredient in the reaction medium has an influence on the structure and the texture of the synthesized materials, which is due to interactions between the actives molecules, the silicate species and the surfactant molecules in the reaction medium.
96

The Role of Oxygen During In Vitro Culture and Immunoisolation of Islets of Langerhans

Fraker, Christopher A 19 April 2011 (has links)
While clinical transplantation of islets of Langerhans for the treatment of insulin dependent Diabetes Mellitus has shown significant promise in recent years, there remains a need for procedural optimizations to improve cell viability, functionality and ultimately, graft longevity. One of the most critical factors to islet cell survival is the proper oxygenation of these highly metabolic cellular aggregates. In culture, islets experience suboptimal oxygen profiles delimited by steep gradients across culture media. When retransplanted, they are subjected to extremes of hypoxia and anoxia, resulting in pronounced graft dysfunction and cell loss, which is further exacerbated when these cells are immunoisolated in polymer matrices. This study examined the effects of improving both in-vitro culture and immunoisolation of islet cells by optimizing oxygen mass transfer via oxygen carriers in the form of perfluorocarbons. Specifically, new systems for these applications were developed utilizing perfluoromoeities and conventional culture (polydimethylsiloxane) and immunoisolation (sodium alginate) matrices. During in vitro culture of islet cells, the use of perfluoro-impregnated PDMS culture platforms enhanced cell recovery, viability and function over the culture period. Additionally, marginal mass transplants of the islets cultured in these novel platforms functioned better in recipients than relevant controls. In immunoisolation, the optimization of perfluorocarbon emulsions was performed investigating the effects of combinations of surfactants and perfluorocarbons on oxygen mass transfer and cell viability. Emulsions were well characterized using particle size analysis by dynamic light scattering, perfluorocarbon inclusion by gravimetry and oxygen diffusivity measurements utilizing fluorescent optodes. A novel method was developed for the assessment of dissolved oxygen content of these emulsions. Optimal emulsions, as determined by predicted/measured oxygen transfer enhancement over relevant controls, were utilized in alginate matrices for microencapsulation of cell lines, initially, and then, islets of Langehans. The effects of these potential improvements were assessed by in-vitro potency assays, including a novel method for assessing glucose stimulated insulin release, and in transplantation efficacy in rodent marginal mass models. While the improvements in culture were promising in cell line studies, the observed benefit did not translate in islet culture. The cause was found to be related to permeability impediments generated from the surfactant components utilized in emulsion manufacture. In addition to the development of several new methods for the characterization of oxygen containing solutions and the potency assessment of isolated islets of Langerhans, the impact of these studies is important in the field of polymer engineering. We observed that the use of Polyethylene glycol (PEG) based materials may limit transport of nutrients and oxygen critical to cells. Additionally, we developed cell culture platforms that enhance the viability, number and function of cultured islet cells, potentially impacting the clinical realm where cell preservation is critical to transplant outcome.
97

Energy transfer enhancement of photon upconversion systems for solar energy harvesting

Kang, Ji-Hwan 02 October 2012 (has links)
Photon energy upconversion (UC), a process that can convert two or more photons with low energy to a single photon of higher energy, has the potential for overcoming the thermodynamic efficiency limits of sunlight-powered devices and processes. An attractive route to lowering the incident power density for UC lies in harnessing energy transfer through triplet-triplet annihilation (TTA). To maximize energy migration in multicomponent TTA-assisted UC systems, triplet exciton diffusivity of the chromophores within an inert medium is of paramount importance, especially in a solid-state matrix for practical device integration. In this thesis, low-threshold sensitized UC systems were fabricated and demonstrated by a photo-induced interfacial polymerization within a coaxial-flow microfluidic channel and in combination with nanostructured optical semiconductors. Dual-phase structured uniform UC capsules allow for the highly efficient bimolecular interactions required for TTA-based upconversion, as well as mechanical strength for integrity and stability. Through controlled interfacial photopolymerization, diffusive energy transfer-driven photoluminescence in a bi-molecular UC system was explored with concomitant tuning of the capsule properties. We believe that this core-shell structure has significance not only for enabling promising applications in photovoltaic devices and photochromic displays, but also for providing a useful platform for photocatalytic and photosensor units. Furthermore, for improving photon upconverted emission, a photonic crystal was integrated as an optical structure consisting of monodisperse inorganic colloidal nanoparticles and polymer resin. The constructively enhanced reflected light allows for the reuse of solar photons over a broad spectrum, resulting in an increase in the power conversion efficiency of a dye-sensitized solar cell as much as 15-20 %.
98

Analysis and entrapment of select antioxidants from chokecherry and Saskatoon berry fruits

Konecsni, Kelly Alyson 03 June 2011
The major objectives of this research were to produce a phenolic rich isolate from two locally grown Saskatchewan fruits, chokecherries and saskatoons, develop an encapsulation system for the phenolic isolate, and test this system for the delivery of the phenolic isolate in an animal (rat) model. Natural phenolic compounds present in plants such as fruits have antioxidant and free radical scavenging activities, which have been proposed to have health benefits. The extraction of these compounds from plants is commonly performed using methanol despite being toxic to both humans and animals. As such, ethanol was investigated for its ability to extract phenolics from plants as a food safe alternative to methanol. Phenolic extraction from chokecherries with ethanol:formic acid:water (EFW) resulted in higher concentrations (9.83 mg gallic acid equivalents (GAE)/g fresh weight) than with methanol:formic acid:water (MFW) (7.97 mg GAE/g fresh weight). Results from saskatoons showed similar phenolic levels of 4.26 and 4.21 mg GAE/g fresh weight with MFW and ethanol (EFW), respectively. These results showed that EFW was a suitable substitute for MFW in phenolic compound isolation from chokecherries and saskatoons, and could be used to produce extracts that were safe for use in foods and feeds. High performance liquid chromatography with photodiode array detection (HPLC-PDA) was used to determine the phenolic compound composition of the raw fruits and their phenolic rich isolates. Chlorogenic acid was identified in both chokecherry and saskatoon samples, and rutin was also shown to be present in saskatoons. These identifications were based on the relative retention time and ultra violet-visual spectra comparisons to standards. Solid phase extraction (SPE) using Amberlite XAD-16 was employed to produce phenolic isolates from chokecherries and saskatoons. HPLC-PDA results determined that there was a ~2.7x and ~1.6x increase in peak area for chokecherries and saskatoons, respectively when SPE was employed. The antioxidant activity of the extracts and isolates was determined using in vitro radical scavenging tests including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2´-azinobis-3-ethylbenzthiazoline-sulphonic acid (ABTS). The EFW chokecherry extract and isolate had the highest overall free radical scavenging activity. Crude fruit extracts exhibited lower free radical scavenging values compared to the isolate samples in both of the assays performed. The fruit phenolic isolates were encapsulated in chitosan (CH) sodium tripolyphosphate (TPP) nanoparticles at a ratio of 4.0:1.0 (CH:TPP). HPLC-PDA was used to determine the entrapment efficiency of phenolic isolates to be 15.9 ± 2.7% and 23.0 ± 7.1% for chokecherries and saskatoons, respectively. Characteristics such as the size, surface potential and phenolic release were determined for the two fruit isolate containing nanoparticles. The size of the nanoparticles were 527.90 ± 74.57 nm and 443.03 ± 15.79 nm for chokecherries and saskatoons, respectively. Both of the nanoparticle systems had positive surface charges at 52.70 ± 2.93 mV and 54.43 ± 1.27 mV for chokecherries and saskatoons, respectively. The release properties of the CH:TPP nanoparticles containing fruit phenolics were examined in enzymatic simulated intestinal fluid and resulted in ~23% and ~28% release of chokecherry and saskatoon phenolics, respectively. Saskatoon phenolic isolates and isolates encapsulated in CH:TPP were gavage fed to rats (six animals in each of the two groups) at a dosage rate of 276.36 ± 9.74 mg/kg body weight. The saskatoon isolate contained 12.44 ± 0.44 mg/kg body weight anthocyanins (~3.30 mg anthocyanin per rat). These animals were sacrificed after 1 h and all stomach tissue samples in each of the treatment groups contained detectable levels of anthocyanins. In the small intestine tissues all six of the saskatoon isolate and three of the encapsulated isolate groups had detectable amounts of anthocyanins, while in the large intestine tissue, only one sample from the isolate group showed detectable amounts of anthocyanins. Although other tissues were tested (brain, heart, kidney and liver), anthocyanins were not detected. Therefore anthocyanins were detected in the gastrointestinal tract of both of the treatment groups. The research performed therefore illustrated that phenolic compounds can be extracted from fruit sources using EFW and can be successfully encapsulated in chitosan tripolyphosphate capsules allowing for targeted delivery in an animal model.
99

Stabilization of linseed oil for use in aquaculture feeds

Nilson, Stephanie Anne 10 December 2008
An experiment was conducted to determine the effect of addition of antioxidants or encapsulation of linseed oil on the oxidative stability of linseed oil and the effect on growth and fatty acid composition of rainbow trout fed these products. Four diets differing only in their lipid sources were prepared by cold extrusion: 1) fish oil (FO), 2) linseed oil (LO), 3) linseed oil (980 g/kg) stabilized with vitamin E (7.5 g/kg) and butylated hydroxytoluene (BHT) (12.5 g/kg) (stabilized linseed oil; SLO) and 4) linseed oil (350 g/kg) containing vitamin E (7.5 g/kg), BHT (12.5 g/kg) and encapsulated in a coating material primarily consisting of hydrogenated palm oil (630 g/kg) (encapsulated linseed oil; ELO). Diets were fed twice daily to rainbow trout to apparent satiation (n=22 / replicate; 7 replicates per treatment) during a 168 day growth trial. Following the growth trial, the fish were humanely euthanized by a sharp blow to the cranium and analyzed for fatty acid composition, thiobarbituraric reactive substances (TBARS), fillet colour and sensory attributes (trained and consumer panels). There were no significant differences between treatments on any of the growth parameters investigated or TBARS levels of fish fillets. Omega-3 polyunsaturated fatty acids of trout fed LO were significantly higher than those fed FO (35.5% of total fatty acids vs. 27.6%) and ELO (28.9%) (P < 0.05). EPA and DHA levels were not significantly different between treatments. Diet samples were stored for 168 days at room temperature in sealed plastic containers. Following storage, the oxidative stability index (OSI) of the FO and LO diets were reduced to 0.00 hours while that of the SLO diet 9.20 hours and the ELO diet was 11.40 hours. Trained panelists determined fish fed FO had a significantly higher aroma intensity and significantly lower aroma desirability and overall acceptability than those fed SLO. The rancid aroma and flavour of the FO-fed fish was significantly higher than fish fed the other treatments (P < 0.05). Consumer panelists found no significant differences between the sensory attributes of fish fed the four experimental diets and exhibited no preference between treatments (P > 0.05). Fillets from fish fed FO had significantly higher values than the other three treatments for redness (3.59 vs values between 1.86 and 2.07) and yellowness (25.35 vs values between 20.51 and 21.22) (P < 0.05). Addition of antioxidants to linseed oil improves its oxidative stability during storage and processing and results in fish fillets with fatty acid composition and consumer acceptance equal or superior to fish fed fish oil.
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Stabilization of linseed oil for use in aquaculture feeds

January 2008 (has links)
An experiment was conducted to determine the effect of addition of antioxidants or encapsulation of linseed oil on the oxidative stability of linseed oil and the effect on growth and fatty acid composition of rainbow trout fed these products. Four diets differing only in their lipid sources were prepared by cold extrusion: 1) fish oil (FO), 2) linseed oil (LO), 3) linseed oil (980 g/kg) stabilized with vitamin E (7.5 g/kg) and butylated hydroxytoluene (BHT) (12.5 g/kg) (stabilized linseed oil; SLO) and 4) linseed oil (350 g/kg) containing vitamin E (7.5 g/kg), BHT (12.5 g/kg) and encapsulated in a coating material primarily consisting of hydrogenated palm oil (630 g/kg) (encapsulated linseed oil; ELO). Diets were fed twice daily to rainbow trout to apparent satiation (n=22 / replicate; 7 replicates per treatment) during a 168 day growth trial. Following the growth trial, the fish were humanely euthanized by a sharp blow to the cranium and analyzed for fatty acid composition, thiobarbituraric reactive substances (TBARS), fillet colour and sensory attributes (trained and consumer panels). There were no significant differences between treatments on any of the growth parameters investigated or TBARS levels of fish fillets. Omega-3 polyunsaturated fatty acids of trout fed LO were significantly higher than those fed FO (35.5% of total fatty acids vs. 27.6%) and ELO (28.9%) (P < 0.05). EPA and DHA levels were not significantly different between treatments. Diet samples were stored for 168 days at room temperature in sealed plastic containers. Following storage, the oxidative stability index (OSI) of the FO and LO diets were reduced to 0.00 hours while that of the SLO diet 9.20 hours and the ELO diet was 11.40 hours. Trained panelists determined fish fed FO had a significantly higher aroma intensity and significantly lower aroma desirability and overall acceptability than those fed SLO. The rancid aroma and flavour of the FO-fed fish was significantly higher than fish fed the other treatments (P < 0.05). Consumer panelists found no significant differences between the sensory attributes of fish fed the four experimental diets and exhibited no preference between treatments (P > 0.05). Fillets from fish fed FO had significantly higher values than the other three treatments for redness (3.59 vs values between 1.86 and 2.07) and yellowness (25.35 vs values between 20.51 and 21.22) (P < 0.05). Addition of antioxidants to linseed oil improves its oxidative stability during storage and processing and results in fish fillets with fatty acid composition and consumer acceptance equal or superior to fish fed fish oil.

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