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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.
161

Policy Brief for realizing green/bio economy with high value Non-Timber Forest Products commercialization in Ethiopia and Sudan

Eshete Wassie, Abeje, Tadesse, Wubalem, Woldeamanuel, Teshale, Mahagaub Elnasri, Hagir, Nigatu, Teklehaymanot, Pretzsch, Jürgen, Alemu, Asmamaw, Elsheikh Mahmoud, Tarig, El Nour Taha, Mohamed January 2017 (has links)
This policy brief deals with the research findings of the collaborative research project “CHAnces IN Sustainability – promoting natural resource based product chains in East Africa” (CHAINS) funded by the Federal Ministry of Education and Research, and the DLR Project Management Agency. It presents the studies investigating the value chains of highland BAMBOO and NATURAL GUM AND RESIN products in Ethiopia as well as GUM ARABIC value chains in Sudan. These products possess high eco¬nomic, social and environ¬mental benefits and untapped potentials. However, their pro-duction and commercialization are con¬strained seriously by various challenges limiting the realization of their potentials. Identified policy options are: • strengthen institutional capacity; • improve infrastructure and support services; • organize necessary information for sustainable utilization planning; • facilitate actors’ communication, innovation and fair partnership. This calls for forest product value chain development that is supported by policy, training, research, technology development and transfer, market linkage that consider private sectors, state, civic organizations, universities and research institutes.
162

Mätosäkerhet vid kalibrering av referensutrustning för blodtrycksmätning : En modell för framtagning av mätosäkerhet för referensmanometer WA 767 / Measurement uncertainty for calibration of reference equipment for blood pressure measurement : A model for obtaining measurement uncertainty of reference manometer WA 767

Patzauer, Rebecka, Wessel, Elin January 2016 (has links)
Avdelningen för Medicinsk teknik på Akademiska sjukhuset har uppdaterat befintliga kalibreringsprotokoll för Welch Allyn 767 som används som referensmanometer vid kalibrering av blodtrycksmätare. I protokollet ska det enligt ISO 9001 och ISO 13485 ingå att vid varje kalibreringspunkt ange mätosäkerheten.  Rutiner kring detta var inte definierade. En modell för att ta fram mätosäkerhet utformades utifrån standardiserade metoder från “Guide to the expression of uncertainty in measurement” och anpassades för att kunna användas på den medicintekniska avdelningen. En mätmetod för kalibrering togs fram och med modellen beräknades mätosäkerhet för en referensmanometer. Mätosäkerheten med definierad mätmetod blev lägre än den av Welch Allyn specificerade mätosäkerheten på ± 3 mmHg. Felfortplantning från kalibrering till blodtrycksmätning undersöktes. Mätosäkerheten ökade i varje steg, varför avdelningen bör ta fram ett protokoll för hur kalibrering genomförs, och på så sätt förbättra spårbarheten. / The department of Medical Technology at Akademiska sjukhuset has updated their current protocol for calibration for Welch Allyn 767, which serves as a reference manometer for blood pressure meters when being calibrated. According to ISO 9001 and ISO 13485, the protocol has to include a measurement uncertainty for every given point of calibration. The routines regarding this were undefined. A model for retrieving measurement uncertainty was designed using standardized methods from “Guide to the expression of uncertainty in measurement” and was customized to be used at the department of Medical Technology. A method for calibration was created and used to calculate the measurement uncertainty for the reference manometer. This measurement uncertainty was smaller than the one specified by Welch Allyn, which was ± 3 mmHg. Propagation of uncertainty from the calibration to the blood pressure measurement was investigated. The measurement uncertainty increased in every step. Therefore, the department should introduce a protocol for how a calibration is performed, and thereby improve the traceability.
163

Mätosäkerhet vid kalibrering av referensutrustning för blodtrycksmätning : En modell för framtagning av mätosäkerhet för referensmanometer WA 767 / Measurement uncertainty for calibration of reference equipment for blood pressure measurement : A model for obtaining measurement uncertainty of reference manometer WA 767

Patzauer, Rebecka, Wessel, Elin January 2016 (has links)
Avdelningen för Medicinsk teknik på Akademiska sjukhuset har uppdaterat befintliga kalibreringsprotokoll för Welch Allyn 767 som används som referensmanometer vid kalibrering av blodtrycksmätare. I protokollet ska det enligt ISO 9001 och ISO 13485 ingå att vid varje kalibreringspunkt ange mätosäkerheten.  Rutiner kring detta var inte definierade. En modell för att ta fram mätosäkerhet utformades utifrån standardiserade metoder från “Guide to the expression of uncertainty in measurement” och anpassades för att kunna användas på den medicintekniska avdelningen. En mätmetod för kalibrering togs fram och med modellen beräknades mätosäkerhet för en referensmanometer. Mätosäkerheten med definierad mätmetod blev lägre än den av Welch Allyn specificerade mätosäkerheten på ± 3 mmHg. Felfortplantning från kalibrering till blodtrycksmätning undersöktes. Mätosäkerheten ökade i varje steg, varför avdelningen bör ta fram ett protokoll för hur kalibrering genomförs, och på så sätt förbättra spårbarheten. / The department of Medical Technology at Akademiska sjukhuset has updated their current protocol for calibration for Welch Allyn 767, which serves as a reference manometer for blood pressure meters when being calibrated. According to ISO 9001 and ISO 13485, the protocol has to include a measurement uncertainty for every given point of calibration. The routines regarding this were undefined. A model for retrieving measurement uncertainty was designed using standardized methods from “Guide to the expression of uncertainty in measurement” and was customized to be used at the department of Medical Technology. A method for calibration was created and used to calculate the measurement uncertainty for the reference manometer. This measurement uncertainty was smaller than the one specified by Welch Allyn, which was ± 3 mmHg. Propagation of uncertainty from the calibration to the blood pressure measurement was investigated. The measurement uncertainty increased in every step. Therefore, the department should introduce a protocol for how a calibration is performed, and thereby improve the traceability.
164

The Effects of Caffeine Gum Administration on Reaction Time and Lower Body Pain During Cycling to Exhaustion

Jankowski-Wilkinson, Andrea Faye 02 September 2008 (has links)
No description available.
165

FLAXSEED (Linum usitatissimum L.) GUM AND ITS DERIVATIVES: PHYSICOCHEMICAL PROPERTIES AND POTENTIAL INTERACTIONS WITH FOOD MACROMOLECULES

2016 April 1900 (has links)
Flaxseed (Linum usitatissimum L.) gum (FG) is a material with many potential food and non-food applications. Consistent performance is critical for FG utilization and this is possible through selection of genotype, characterization and optimization of constituents, and chemical modification. Physico-chemical and functional properties of FG aqueous solutions from six Canadian flaxseed cultivars were investigated. FG yield, carbohydrate composition, protein content, and zeta potential (ζ) varied among these cultivars. FG solution properties were also affected by temperature, solution pH, NaCl concentration, and sucrose concentration. Detailed studies were conducted on CDC Bethune FG (FGB) proteins that were separated by 2D-gel electrophoresis. Conlinin was identified as the major protein. Protease treatment decreased FGB solution emulsification properties suggesting that conlinin might enhance emulsification. Formation of BSA-FGB coacervates was monitored by turbidimetric analysis as a function of solution pH, biopolymer mixing ratio, NaCl and urea. Coacervates were stabilized primarily by attractive electrostatic forces and secondarily by hydrogen bonds. Further, anionic carboxymethyl ether moieties were introduced to FGB structure through ether forming reactions using monochloroacetic acid (MCA) to produce products with uniform properties. The highest degree of substitution (DS) was obtained at 70 °C, 7.0 M NaOH, and a molar ratio of MCA to FGB of 10:1 over 3 h. Carboxymethylated FGB (CMFG) exhibited both modified surface morphology and thermal behaviour. Solutions of CMFG demonstrated shear-thinning behaviour and apparent viscosity decreased with increased DS. A more liquid-like flow behaviour was observed for CMFG as DS increased. Findings here will introduce and expand FG applications in food or related fields with targeted performance.
166

Formulation et caractérisation d'une forme buccale mucoadhésive thermogélifiante pour administration de sulfate de salbutamol / Formulation and characterization of a thermogelling mucoadhesive buccal form for salbutamol sulfate administration

Zeng, Ni 21 April 2015 (has links)
Le traitement de l’asthme concerne une large population et fait appel très majoritairement à une administration par voie pulmonaire. Cette voie présente certains inconvénients qui pourraient être palliés par le recours à la voie buccale comme envisagé dans cette étude, avec une amélioration attendue de la compliance et de la biodisponibilité. Aussi ce travail a eu pour objectif de développer et caractériser une formulation mucoadhésive thermogélifiante à base de salbutamol. Au regard des contraintes liées à la voie buccale et à la prise en charge du traitement de l’asthme aigu, les principales propriétés pharmacotechniques attendues pour optimiser la biodisponibilité de cette formulation ont été : (i) une gélification optimale autour de 30°C après pulvérisation pour faciliter notamment l’administration ; (ii) des propriétés mécaniques et mucoadhésives importantes pour assurer un maintien de la forme au site d’absorption ; (iii) une cinétique de libération compatible avec le traitement de la phase aigüe de la pathologie. Le choix des excipients a été défini afin d’avoir la plus grande innocuité de la formulation finale. Les travaux expérimentaux ont mis en évidence l’intérêt de certaines techniques innovantes pour la caractérisation de ce type de formulation comme notamment l’étude de libération à l’aide de l’appareil de dissolution à flux continu, la détermination de la cytotoxicité par microscopie holographique digitale et l’évaluation de la mucoadhésion in vitro et in vivo par imagerie. Les résultats ont aussi permis de proposer des modèles mathématiques pour l’interprétation des mécanismes de libération du salbutamol et quantifier l’importance des phénomènes de diffusion et d’érosion. Les conclusions de cette étude sont favorables à la poursuite du développement en vue d’une commercialisation. / The treatment of asthma concerns a large population and generally necessitates an administration by the pulmonary route. This route has some drawbacks which could be overcome by the buccal route, like considered in this study expecting an improvement of the compliance and the bioavailability. The aim of this work was to develop and characterize a thermogelling mucoadhesive formulation containing salbutamol sulfate. The main properties of the formulation were: (i) thermogelation around 30°C to facilitate the administration by spray; (ii) strong mechanical properties and high mucoadhesive strength to maintain the formulation in situ; (iii) drug release kinetics adapted to the treatment. The excipients were selected with regard to the final formulation safety. The experimental work emphasized the great interest of certain techniques in the characterization of this kind of formulation, for example the drug release study using flow through apparatus, the cytotoxicity study using digital holographic microscopy and also the mucoadhesion study by in vivo imaging. The use of mathematical models provided a relevant understanding of drug release mechanisms. The conclusion of this study is favorable to a further development of the project for a future marketing.
167

Propriétés interfaciales et émulsifiantes de gomme d'Acacia senegal, Acacia seyal et de leurs fractions / Interfacial and emulsifying properties of Acacia senegal and Acacia seyal gum and their fractions

Aphibanthammakit, Chutima 29 October 2018 (has links)
Les gommes d’Acacia (AG, E414EC) sont largement utilisées par ses propriétés stabilisantes, émulsifiantes et filmogènes. Le but de ce projet de thèse consiste à caractériser les propriétés interfaciales et émulsifiantes des gommes d’Acacia. Les études des propriétés interfaciales liquide-liquide ont confirmé que l’A. senegal permettait une plus grande diminution de la tension interfaciale et une formation plus rapide de films à l’interface. Ceci est en accord avec sa teneur plus élevée en AGP de masse molaire élevée riche en protéine, la meilleure accessibilité de la partie protéique et la plus grande flexibilité moléculaire par rapport à A. seyal. De même, ces avantages biochimiques et structuraux de l’A. senegal se sont avérés être impliqué dans les propriétés émulsifiantes des gommes. Les résultats d'une approche innovante visant à contrôler la teneur en AGP de masse molaire élevée riche en protéines dans le milieu et la concentration totale de gomme par le mélange de deux fractions bien caractérisées isolées chez A. senegal ont confirmé la synergie fonctionnelle entre la quantité des AGP de masse molaire élevée riche en protéines et la concentration totale en gomme. De plus, en présence de quantités élevées d'AGP de masse molaire élevée riches en protéines, les émulsions étaient stables contre la floculation/coalescence en raison de la forte teneur en protéines permettant une répulsion électrostatique entre les gouttelettes et la viscosité apparente élevée du milieu. Celles-ci étaient en accord lorsque les propriétés émulsifiantes de A. senegal et A. seyal ont été comparées. En effet, A. senegal contient une plus grande quantité d'AGP de masse molaire élevée riches en protéines et d'acides uroniques, et sa dispersion présente une viscosité apparente supérieure à celle d'A. seyal. En outre, lorsque les gommes d'Acacia étaient utilisées sous forme de films séchés, la grande teneur en AGP riches en protéines de masse molaire élevée et la bonne accessibilité des fragments protéiques d'A. senegal permettaient aux films d’avoir une surface homogène lisse avec des propriétés hydrophobes caractéristiques. En revanche, les films de A. seyal étaient irréguliers et constitués d'une organisation répétitive comme de nombreuses grosses particules uniformément réparties sur la surface par rapport au faible degré de ramification, une teneur élevée en arabinose favorisant les liaisons hydrogènes intra et inter moléculaires et une forte capacité d'hydratation chaînes polysaccharidiques de A. seyal. Selon les résultats, cette thèse apporte de nouvelles connaissances sur la relation entre la composition biochimique, les propriétés structurales et physico-chimiques, pour la première fois, dans les deux aspects de la gomme, à savoir sous forme de dispersion liquide et de films séchés.Mots clés : gomme d’Acacia, propriétés interfaciales et émulsifiantes, arabinogalactane-protéines, arômes / Acacia gums (AG, E414 EC) are widely used for its stabilizing, emulsifying and film-forming properties. The aim of this project is to characterize the interfacial and emulsifying properties of Acacia gums. The main results from liquid-liquid interfacial properties study confirmed that A. senegal showed a faster decrease of interfacial tension and a more rapid interfacial film formation. These were in agreement to its greater content of high molar mass-protein AGPs content, the more accessibility of proteinaceous moieties, and the higher molecular flexibility compared to A. seyal. In the same vein, these biochemical and structural advantages of A. senegal were found to be involved in the emulsifying properties of gums. The results from an innovative approach aiming to control high molar mass protein-rich AGPs content in bulk and the total concentration of gum by mixing two well characterised fractions isolated from A. senegal confirmed the functional synergism between the amount of high molar mass protein-rich AGPs and the total gum concentration. Moreover, in the presence of high molar mass protein-rich AGPs in high amount, the emulsion became stable to flocculation/coalescence due to the great protein content allowing electrostatic repulsion between droplets and the high bulk apparent viscosity. These were in agreement when the emulsifying properties of A. senegal and A. seyal were compared. Indeed, A. senegal containing a greater amount of high molar mass protein rich AGPs and uronic acids and its dispersion having a higher apparent viscosity than A. seyal allowing the former to form emulsion with a more stability. Besides, when Acacia gums were used in the form of dried film, the great content of high molar mass protein-rich AGPs and the good accessibility of proteinaceous moieties of A. senegal allowed the smooth homogeneous surface with a hydrophobic characteristic properties of A. senegal dried films. In contrast, A. seyal films was irregular and composed of a repetitive organization as numerous large particle uniformly distributed on surface in the relation to the low degree of branching, high arabinose content favoring intra and inter molecular hydrogen bonding and high hydration ability causing aggregation of polysaccharide chains of A. seyal. According to the results, this thesis brings new knowledge of the relationship between biochemical composition, structural and physicochemical properties, for the first time, across both aspects of gum, i.e. in the form of liquid dispersion and dried films.Keywords: Acacia gums, interfacial and emulsifying properties, arabinogalactan proteins, aroma compounds
168

Formulation et caractérisation d'une forme buccale mucoadhésive thermogélifiante pour administration de sulfate de salbutamol / Formulation and characterization of a thermogelling mucoadhesive buccal form for salbutamol sulfate administration

Zeng, Ni 21 April 2015 (has links)
Le traitement de l’asthme concerne une large population et fait appel très majoritairement à une administration par voie pulmonaire. Cette voie présente certains inconvénients qui pourraient être palliés par le recours à la voie buccale comme envisagé dans cette étude, avec une amélioration attendue de la compliance et de la biodisponibilité. Aussi ce travail a eu pour objectif de développer et caractériser une formulation mucoadhésive thermogélifiante à base de salbutamol. Au regard des contraintes liées à la voie buccale et à la prise en charge du traitement de l’asthme aigu, les principales propriétés pharmacotechniques attendues pour optimiser la biodisponibilité de cette formulation ont été : (i) une gélification optimale autour de 30°C après pulvérisation pour faciliter notamment l’administration ; (ii) des propriétés mécaniques et mucoadhésives importantes pour assurer un maintien de la forme au site d’absorption ; (iii) une cinétique de libération compatible avec le traitement de la phase aigüe de la pathologie. Le choix des excipients a été défini afin d’avoir la plus grande innocuité de la formulation finale. Les travaux expérimentaux ont mis en évidence l’intérêt de certaines techniques innovantes pour la caractérisation de ce type de formulation comme notamment l’étude de libération à l’aide de l’appareil de dissolution à flux continu, la détermination de la cytotoxicité par microscopie holographique digitale et l’évaluation de la mucoadhésion in vitro et in vivo par imagerie. Les résultats ont aussi permis de proposer des modèles mathématiques pour l’interprétation des mécanismes de libération du salbutamol et quantifier l’importance des phénomènes de diffusion et d’érosion. Les conclusions de cette étude sont favorables à la poursuite du développement en vue d’une commercialisation. / The treatment of asthma concerns a large population and generally necessitates an administration by the pulmonary route. This route has some drawbacks which could be overcome by the buccal route, like considered in this study expecting an improvement of the compliance and the bioavailability. The aim of this work was to develop and characterize a thermogelling mucoadhesive formulation containing salbutamol sulfate. The main properties of the formulation were: (i) thermogelation around 30°C to facilitate the administration by spray; (ii) strong mechanical properties and high mucoadhesive strength to maintain the formulation in situ; (iii) drug release kinetics adapted to the treatment. The excipients were selected with regard to the final formulation safety. The experimental work emphasized the great interest of certain techniques in the characterization of this kind of formulation, for example the drug release study using flow through apparatus, the cytotoxicity study using digital holographic microscopy and also the mucoadhesion study by in vivo imaging. The use of mathematical models provided a relevant understanding of drug release mechanisms. The conclusion of this study is favorable to a further development of the project for a future marketing.
169

Polpa de guavira (Campomanesia cambessedeana Berg) desidratada em spray dryer: efeitos das condições de processo e composição da alimentação nas propriedades físico químicas e atividade antioxidante / Guavira (Campomanesia cambessedeana Berg) pulp dehydrated in spray dryer: effects of process conditions and feed composition on the physicochemical properties and antioxidant activity

Chung, Monique Mi Song 04 February 2016 (has links)
O objetivo desse trabalho foi obter polpa de guavira desidratada por atomização, utilizando maltodextrina ou goma arábica como agentes carreadores. Inicialmente, avaliou-se a influência das condições de processo, temperatura do ar de secagem (130, 155 e 180) °C e vazão volumétrica da mistura (20 e 40) mL/min, o tipo e concentração de agente carreador (10 e 20) % nas características físicas, físico-químicas e atividade antioxidante do produto obtido. As propriedades analisadas foram umidade, atividade de água, higroscopicidade, solubilidade, cor, distribuição e tamanho médio de partículas, morfologia, compostos fenólicos totais e atividade antioxidante. A temperatura do ar de secagem e a vazão volumétrica de alimentação influenciaram significativamente todas as propriedades da guavira em pó. A umidade e atividade de água apresentaram os menores valores na temperatura intermediária, independentemente do tipo e concentração do carreador usado. A solubilidade das amostras adicionadas de maltodextrina foram superiores às amostras com goma arábica. O aumento da concentração de agente carreador, em geral, proporcionou um aumento no parâmetro L* e diminuição dos parâmetros a* e b*, tornando as amostras mais claras e reduzindo as tonalidades vermelha e amarela. A guavira em pó apresentou coloração próxima do amarelo e marrom, com grande variação nos parâmetros de cor C* e H* em função das diferentes condições de secagem. A distribuição do tamanho de partículas não teve um padrão definido e o tamanho médio das amostras com maltodextrina foram maiores do que as com goma arábica para a temperatura do ar a 130 °C. No entanto, para as outras temperaturas (155 e 180) °C não houve um comportamento específico do tamanho das partículas em função da vazão de alimentação, tipo e ou concentração de agente carreador. A análise de microscopia eletrônica de varredura permitiu observar que as partículas obtidas tanto com maltodextrina como goma arábica apresentaram formato esférico, superfície rugosa e com adesão de partículas menores nas de maior tamanho, sendo que a superfície das partículas com goma arábica também apresentaram concavidades. A atividade antioxidante foi superior quando utilizada a temperatura de secagem intermediária. A partir das condições selecionadas na primeira etapa (temperatura do ar de 155 °C, vazão volumétrica da mistura de 40 mL/min e 10% de maltodextrina ou goma arábica) a polpa de guavira em pó foi caracterizada quanto a temperatura de transição vítrea, as isotermas de adsorção e a estabilidade à estocagem do ácido ascórbico, compostos fenólicos totais e da atividade antioxidante da polpa de guavira em pó produzida por spray drying ao longo de 120 dias. As temperaturas de transição vítrea foram de (25,2 ± 2,7 °C e 31,4 ± 0,4) °C para os pós produzidos com goma arábica e maltodextrina, respectivamente. O modelo de BET apresentou ajuste muito bom (R2>0,99) para descrever o comportamento de sorção de água das amostras nas temperaturas de (20, 30 e 40) °C. A polpa de guavira em pó produzida com goma arábica apresentou maior adsorção de água do que as amostras obtidas com maltodextrina. No estudo da estabilidade, as amostras foram acondicionadas em embalagem de polietileno laminado e armazenadas a 25 °C e umidade relativa de 75%. A embalagem de polietileno laminado foi eficiente na manutenção do teor de ácido ascórbico e atividade antioxidante da guavira em pó por um período de 120 dias, independente do carreador adicionado. O teor de compostos fenólicos para a guavira em pó com goma arábica apresentou uma redução nos primeiros 22 dias, contudo a amostra com maltodextrina manteve-se estável durante 120 dias de armazenamento. / The aim of this work was to obtain dried guavira pulp by spray drying, using maltodextrin or arabic gum as carrier agents. Initially, it was evaluated the influence of the process conditions, inlet air temperature (130, 155 e 180) °C and mixture feed flow rate (20 e 40) mL/min, carrier agent type and concentration (10 e 20) % in physical, physicochemical properties and antioxidant activity of the product. The analyzed properties were moisture content, water activity, higroscopicity, solubility, distribution and average particle size, morphology, total phenolic compounds and antioxidant activity. The inlet air temperature and mixture feed flow significantly influenced all the properties of guavira powder. The moisture content and water activity showed lower values in intermediate temperature, independent of the carrier agent type and concentration. The solubility of the samples with maltodextrin were higher than the samples with arabic gum. Increasing the carrier agent concentration generally resulted in an increase of the parameter L* and a reduction of a* and b* parameters, making lighter samples and reducing the red and yellow hues. The color of the guavira powder presented next to yellow and brown coloring, with great variation in parameters C* and H* depending on the different drying conditions. The size distribution of the particles had no definite pattern and the particles average size of the samples with maltodextrin were higher the samples with arabic gum for the inlet air temperature at 130 °C. However, for the other temperatures (155 and 180) °C there is a specific behavior of the particle size depending of the feed flow rate, carrier agent type and concentration. The scanning electronic microscopic analysis observed that the particles obtained with maltodextrin or arabic gum presented spherical, roughness surface and adhesion of the smaller particles into larger, the particles with arabic gum also presented concavities. The antioxidant activity was higher at intermediate inlet air temperature. From the selected conditions at the first phase (inlet air temperature of 155 °C, feed flow rate of 40 mL/min and 10% of maltodextrina or arabic gum) the guavira pulp powder were evaluated the glass transition temperature, the adsorption isotherms and the storage stability of ascorbic acid and antioxidant activity of the guavira powder produced to over 120 days. The glass transition temperatures were (25,2 ± 2,7 °C e 31,4 ± 0,4) °C for the powder obtained with arabic gum and maltodextrin, respectively. The BET model presented good adjustment (R²>0,99) to describe the water sorption behavior of the samples at test temperatures of (20, 30 e 40) °C. The guavira powder with arabic gum showed higher water adsorption than the samples with maltodextrin. In the stability study, samples were packed in polyethylene-laminated packaging and stored at 25 °C and relative humidity of 75%. The packaging was effective in maintaining ascorbic acid and antioxidant activity of the guavira powder for a period of 120 days for samples with the addition of maltodextrin and gum arabic. The content of phenolic compounds for guavira powder with gum arabic showed a reduction in the first 22 days, but the sample with maltodextrin remained stable for 120 days of storage.
170

Propriétés volumétriques des Arabinogalactan-protéines d'exsudats de gommes d'Acacia / Volumetric properties of Arabinogalactan-proteins from Acacia Gum

Mejia Tamayo, Verónica 28 November 2018 (has links)
La gomme d’Acacia est l’une des plus anciennes gommes naturelles dans le monde et la plus connue. Elle est définie comme l’exsudat gommeux produit par les arbres d’Acacia senegal et Acacia seyal. Les gommes d’Acacia sont composées d’arabinogalactanes protéines (AGPs), faiblement chargés, hyperbranchés avec une forte proportion de sucres (90%) et d’environ 1-3% de protéines et de minéraux. Malgré ses nombreuses applications industrielles, les connaissances sur ses propriétés volumétriques (hydrostatiques et hydrodynamiques) restent à améliorer. Ces propriétés peuvent être liées à la flexibilité et l’hydratation des molécules qui déterminent les propriétés fonctionnelles importantes comme les propriétés interfaciales. L'objectif de cette thèse est l’étude des propriétés volumétriques d’AGPs de la gomme d’Acacia. L’étude a été faite sur les principales variétés des gommes d’Acacia, A. senegal et A. seyal, ainsi que des fractions macromoléculaires d’A. senegal, obtenues par la chromatographie d'interaction hydrophobe et d'échange ionique. Les principaux résultats ont montré que les AGPs de gomme d’Acacia ont une structure semi flexible. De plus, des différences dans la flexibilité et l’hydratation entre les fractions d’AGPs ont été montré. Ces différences ont été expliquées par leurs différences en composition, polarité, masse molaire, forme et conformation. De plus, un comportement intermédiaire entre des protéines et des polysaccharides linéaires ont été montré. Finalement, un effet des agrégats d’AGPs sur les propriétés volumétriques a été mis en avance. / Acacia gum is the oldest and most widely known and used gum, it is a dried gummy exudate from the leaves and branches of the Acacia senegal and Acacia seyal trees. Acacia gums are weakly charged, amphiphilic hyperbranched arabinogalactan-proteins (AGPs). They are composed of about 90% polysaccharides and from 1-3% of proteins and minerals. In spite of the widely spread of industrial usage of A. gums, their volumetric properties (hydrostatic and hydrodynamic) have not been well studied. These properties have been linked to important properties such as flexibility and hydration of the molecule, which are related to important functional properties of A. gums (e. g. interfacial properties). The main objective of this PhD thesis was to study the volumetric properties of AGPs from Acacia gums exudates. For this effect, the main commercial species, A. senegal and A. seyal, and the macromolecular fractions of the former, obtained via hydrophobic interaction and ionic exchange chromatographies were studied. The main results showed that AGPs from Acacia gums have a semi-flexible structure. However, differences in their flexibility and hydration were seen among AGP fractions. These differences were explained based on their composition, polarity, molar mass, shape and conformation. Furthermore, an intermediate behavior between proteins and linear polysaccharides was evidenced. In addition, an effect of the presence of AGP based aggregates on the volumetric properties was seen.

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