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Listiohadi, Yuanita D. "The caking of lactose." Thesis, View thesis, 2004. http://handle.uws.edu.au:8081/1959.7/25753.
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This project has investigated the mechanism of caking of lactose and identified some possible solutions to minimise caking of lactose and dairy powders, additional to those suggested in the literature. A background to lactose and caking is given. The problems of caking are identified and discussed. The project adds information to the knowledge on the polymorphic forms of lactose and their inter-relationships due to moisture sorption and processes such as milling. This information and many others in the literature are used to complete the simplified lactose conversion diagram developed by King [1965] and improved by Walstra, et al. [1999], which has been widely used in the literature as a guide for lactose manufacturing, processing, and storage.
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Listiohadi, Yuanita D. "The caking of lactose /." View thesis, 2004. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20041108.084200/index.html.
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Hosseini, Seyed Alireza. "MODELING PARTICLE FILTRATION AND CAKING IN FIBROUS FILTER MEDIA." VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/2530.
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This study is aimed at developing modeling methodologies for simulating the flow of air and aerosol particles through fibrous filter media made up of micro- or nano-fibers. The study also deals with modeling particle deposition (due to Brownian diffusion, interception, and inertial impaction) and particle cake formation, on or inside fibrous filters. By computing the air flow field and the trajectory of airborne particles in 3-D virtual geometries that resemble the internal microstructure of fibrous filter media, pressure drop and collection efficiency of micro- or nano-fiber filters are simulated and compared with the available experimental studies. It was demonstrated that the simulations conducted in 3-D disordered fibrous domains, unlike previously reported 2-D cell-model simulations, do not need any empirical correction factors to closely predict experimental observations. This study also reports on the importance of fibers’ cross-sectional shape for filters operating in slip (nano-fiber filters) and no-slip (micro-fiber filters) flow regimes. In particular, it was found that the more streamlined the fiber geometry, the lower the fiber drag caused by a nanofiber relative to that generated by its micron-sized counterpart. This work also presents a methodology for simulating pressure drop and collection efficiency of a filter medium during instantaneous particle loading using the Fluent CFD code, enhanced by using a series of in-house subroutines. These subroutines are developed to allow one to track particles of different sizes, and simulate the formation of 2-D and 3-D dendrite particle deposits in the presence of aerodynamic slip on the surface of the fibers. The deposition of particles on a fiber and the previously deposited particles is made possible by developing additional subroutines, which mark the cells located at the deposition sites and modify their properties to so that they resemble solid or porous particles. Our unsteady-state simulations, in qualitative agreement with the experimental observations reported in the literature, predict the rate of increase of pressure drop and collection efficiency of a filter medium as a function of the mass of the loaded particles.
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Specht, Dauntel Wynette. "Caking of granular materials an experimental and theoretical study /." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013727.
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Penn, Stephanie Ann. "Effects of Starch-Based Anti-Caking Agents on Browning of Shredded Mozzarella Cheese." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/42865.
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The effects of starch-based anti-caking agents on the browning of Mozzarella cheese were evaluated in this experiment. Six commercially available anti-caking agent treatments were examined and color measurements indicated that the starch-based anti-caking agents produced a baked cheese with a greater degree of browning than the samples treated with cellulose based anti-caking agents or no treatment (control). The cellulose-based treatments and the control also had a significantly greater moisture loss than the potato starch-based treatments. A negative correlation between percent moisture loss and the amount of browning was found (R2=0.51). The average surface temperature was at least 16â aC higher for the treatments containing potato starch than for the cellulose-based treatments. A significant relationship between average surface temperature and browning was also found (R2=0.67). These relationships suggest that the starch-based treatments impeded moisture loss, which decreased the amount of evaporative cooling. An increase in surface temperature resulted from the decrease in the amount of evaporative cooling and thus the Maillard reaction was accelerated leading to increased browning.
The effects of the starch source were examined using starches from corn, rice and wheat. These starches were compared to commercially available potato starch and cellulose anti-caking agents. All starch sources were found to produce a greater degree of browning on the cheese sample compared to the cellulose treatment and control.
Four adjuncts treatments, including dimethypolysiloxane, lactic acid, partially hydrogenated sunflower oil, and a combination of the dimethylpolysiloxane and sunflower oil were added to cheese treated with potato starch to determine if a reduction in the degree of browning could be achieved. No differences in browning between the potato starch treatment and those with added adjuncts were found.Master of Science
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De, Waal Fransie. "Investigation of coal agglomeration in a non-pressurized gasifier / Fransie de Waal." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2822.
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Akins, Maureen Lynch. "Effects of Starch-based Anti-caking Agents on the Functional Properties of Shredded Mozzarella Cheese." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35783.
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Mozzarella cheese production has been gaining market share due in part to increasing market for pizza and ready to eat food items. Anti-caking agents are utilized in the production of shredded cheese for reducing clumping and increasing the appearance of separate cheese shreds. Six anti-caking agents were applied to low moisture part skim Mozzarella cheese and examined for effects on three major functional properties of Mozzarella cheese; meltability, stretchability, and free oil formation. Meltability determination utilizing a fabricated UW Meltmeter resulted in no significant differences between untreated samples (control) and samples treated with anti-caking agents containing cellulose, potato starch or mixtures including dextrose. Stretchability measurements taken using a modified helical viscometry procedure also resulted in no significant differences between control and treated samples. Significant differences were found when comparing free oil percentages obtained from varying treatments of anti-caking agents. A mixture of potato starch and cellulose resulted in the lowest level of free oil among all samples tested.
Because potato starch treated samples performed equally to cellulose treated samples in both meltability and stretchability testing, anti-caking agents containing potato starch could be considered as an alternative to cellulose-based anti-caking agents. In addition, the use of potato starch alone and in conjunction with powdered cellulose has been shown to be more effective for free oil control. By treating with potato starch, functional properties of shredded Mozzarella cheese have been positively altered in a way which may increase acceptability by consumers.Master of Science
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Afrassiabian, Zahra. "Multiscale investigation of caking phenomenon of lactose powders : from physico-chemical aspects to industrial applications." Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2475/document.
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Cette thèse porte sur le problème fondamental du mottage des poudres suite aux mécanismes de transition de phase. Le projet vise à étudier l'impact des facteurs intrinsèques (structure moléculaire des matériaux, propriétés physiques et/ou physicochimiques, etc.) ou des facteurs environnementaux (conditions de stockage ou paramètres de procédé) sur la stabilité de la structure des poudres. Plus précisément, notre étude a mis en évidence le rôle prépondérant du phénomène de cristallisation et des transitions entre les différents polymorphes du lactose. L'accent a été mis sur le rôle des phénomènes de cristallisation et de la transition de phase dans l'apparition du mottage des poudres de lactose. Deux cas ont particulièrement retenu notre attention: (1) des poudres de lactose monohydrate contenant une fraction de particules amorphes et (2) des échantillons de poudre anhydre composés des anomères α et β du lactose. Dans les deux cas, le mottage a été induite par l'exposition des échantillons à l'air humide, soit dans un dispositif de sorption dynamique de vapeur (SPS), soit par des tests accélérés utilisant deux appareils conçus et réalisés dans notre laboratoire (CLAIR & OLAF). Nos résultats ont montré que, dans les deux cas, la principale cause de prise en masse était la formation de lactose monohydrate, qui est la forme la plus stable parmi tous les polymorphes de lactose. Cependant, les mécanismes élémentaires, les étapes limites et la cinétique du processus de transformation étaient différents dans chaque cas. Les paramètres les plus déterminants étaient l’humidité relative et la température alors que la pression n’a pas eu d’effet significatif. La résistance mécanique des échantillons mottés était étroitement liée au taux et à la cinétique de cristallisation. Enfin, des simulations numériques basées sur la méthode des éléments discrets (DEM) de la résistance mécanique des échantillons mottés ont été réalisées. Le modèle permet de décrire le comportement des échantillons mottés soumis à des contraintes mécaniques de compression ou de tractionThis PhD study focuses on the fundamental problem of powder caking due to phase transition mechanisms. The project aims to study the impact of intrinsic factors (molecular structure of materials, physical and/or physicochemical properties, etc.) or environmental factors (storage conditions or process parameters) on the stability of the structure of powders. More precisely, our study has highlighted the preponderant role of the crystallization phenomenon and the transitions taking place between the different polymorphs of lactose. Emphasis was placed on the role of crystallization phenomena and phase transition on the advent of lactose powder caking. Two cases attracted particular attention: (1) lactose monohydrate powders containing a fraction of amorphous particles and (2) anhydrous powder samples composed of ð and anomers of lactose. In both cases, the caking was induced by exposure of the samples to moist air, either in a Dynamic Vapor Sorption device (SPS) or in accelerated caking tests using two home-made equipment (CLAIR & OLAF). Our results showed that in both cases, the main cause of caking was the formation of lactose monohydrate, which is the most stable form among all lactose polymorphs. However, the elementary mechanisms, the limiting steps and the kinetics of the transformation process were different in each case. The more influencing parameters were the relative humidity and the temperature whereas the pressure has no significant effect. The yield stress of caked samples was closely linked with crystallization extent and kinetics. Finally, numerical simulations based on Discrete Element Method (DEM) of mechanical resistance of caked samples were performed using the "beam model". The model allows describing the behavior of the caked samples subjected to compressive or tractive mechanical stresses
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Li, Hangsheng [Verfasser], Jörg [Akademischer Betreuer] Kressler, and Roland [Akademischer Betreuer] Weidisch. "Design of amphiphilic anti-caking systems for solid particles / Hangsheng Li. Betreuer: Jörg Kressler ; Roland Weidisch." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2010. http://d-nb.info/1024937461/34.
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Vissotto, Fernanda Zaratini. "Estudo do processo de aglomeração com vapor e perda de qualidade por caking de achocolatados em pó." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256468.
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Orientadores: Florencia Cecilia Menegalli, Maria Isabel RodriguesTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Os achocolatados em pó são formulados com a mistura de cacau, açúcar, maltodextrina e aromas, podendo conter derivados lácteos. Para se obter uma adequada reconstituição em líquidos, os achocolatados são submetidos aos processos de lecitinação (adição de um agente tensoativo: lecitina de soja) e aglomeração com vapor. Um dos objetivos desse estudo foi o de avaliar os efeitos das variáveis do processo de aglomeração com vapor (pressão do vapor, temperatura do secador rotativo, vazão de sólidos da alimentação e frequência de rotação do secador) sobre as características físicas e físico-químicas de achocolatados em pó. A aglomeração com vapor levou a um aumento do diâmetro médio de partículas, sendo mais pronunciado no produto formulado com o açúcar moído. O processo foi responsável pelo escurecimento e redução da umidade dos achocolatados, além da diminuição dos tempos de molhabilidade. Adicionalmente foi caracterizada a morfologia dos grânulos de achocolatado, obtidos em diferentes condições operacionais do aglomerador (máxima, média e mínima), utilizando os descritores de tamanho e forma. Os resultados mostraram que não existe diferença entre os descritores de forma e quanto aos descritores de tamanho verificou-se diferença entre as condições de processo para grânulos maiores que 600 ?m. Concluiu-se que os grânulos de achocolatado aglomerados apresentaram formato alongado. Foram também determinadas as transições de fase e as temperaturas de transição vítrea (Tg) de achocolatados em pó e dos seus principais constituintes. Durante a aglomeração com vapor a alta temperatura levou o açúcar moído a uma condição acima da sua Tg, passando a ser esse componente um veículo para a granulação. A Tg da maltodextrina é pequena em atividades de água elevadas (Tg= - 4,9 °C; Aa= 0,843), o que também a torna um veículo para o processo de aglomeração. No cacau em pó alcalino foi observada a fusão da manteiga de cacau (aparecimento das formas polimórficas ?v e ?). Para o achocolatado lecitinado verificou-se que a Tg aumenta com o incremento da atividade de água do meio, portanto para esse tipo de produto a água, ao ser adsorvida, não consegue interagir com o material, não sendo verificado o efeito plasticizante. Para o achocolatado aglomerado com vapor verificou-se que a Tg diminuiu com o aumento da atividade de água do meio (efeito plasticizante). A evolução do caking dos constituintes dos achocolatados mostrou que o cacau em pó apresentou baixa higroscopicidade (pequeno aumento do ângulo de repouso com o tempo), pequena formação de aglomerados e a ausência do caking. A medida da força de compressão dos agregados formados mostrou que a sacarose formou pontes mais rígidas entre as partículas que a maltodextrina. Foi também monitorada a estabilidade de achocolatados em pó lecitinados e aglomerados com vapor, estocados a 25 e 35 °C, numa umidade relativa de 84%, buscando-se simular um clima quente e úmido (região norte do Brasil). Ao longo do tempo, verificou-se aumento do ângulo de repouso e escurecimento dos produtos. O achocolatado lecitinado mostrou-se mais susceptível ao empedramento que o aglomerado, com a formação de grumos a partir do 63° dia de armazenamento
Abstract: Cocoa beverage powders consist of a mixture of cocoa, sugar, maltodextrin, flavors, and may contain dairy products. To obtain products with adequate reconstitution in liquids, the cocoa beverage powders are subjected to the processes of lecithination (addition of the surfactant soy lecithin) and steam agglomeration. One objective of this study was to evaluate the effects of the main variables of the steam agglomeration process (vapor pressure, temperature of rotary dryer, solid feed rate and dryer rotation frequency) on the physical and physicochemical characteristics of cocoa beverage powders. The steam agglomeration led to an increased average particle diameter, being more pronounced in the product formulated with granulated sugar. The process was responsible for powder darkening, reduction of the product¿s moisture and decrease in the wettability. Additionally, the morphology of the cocoa beverage powder granules was characterized in different operating conditions of the steam agglomerator (maximum, average and minimum) using the descriptors of size and shape. There were no differences between the shape descriptors and as to the size descriptors there were differences in the process conditions studied for the granules of size above 600 ?m. It was observed that the steam agglomerated cocoa beverage granules had a more elongated shape. It was also determined phase transitions and the glass transition temperature (Tg) of cocoa beverage powders and the main constituents of these products. During the steam agglomeration, the high temperature led the granulate sugar to a condition above its Tg, making this ingredient a granulation vehicle. The Tg of maltodextrin is small at higher water activities (Tg = - 4.9 °C, aw = 0.843), which makes this ingredient a vehicle for the agglomeration process. For the alkaline cocoa powder the phase transition observed is the melting of the cocoa butter with the appearance of polymorphic forms ? and ?v. For the lecithinated cocoa beverage powder, it was verified that the Tg increases with the increasing of the water activity, which leads to the conclusion that for this type of product the adsorbed water cannot interact with the material, and the plasticizing effect is not noted. For the steam agglomerated cocoa beverage powder it was observed that the Tg decreases with increasing water activity (plasticizing effect). The evolution of the caking for the constituents of cocoa beverage powders showed that the cocoa powder had low hygroscopicity (small increase of the repose angle with time), little formation of granules and the absence of caking. The measurement of the compression strength of the aggregates showed that sucrose formed bridges more rigid between the particles than maltodextrin. Stability of lecithinated and steam agglomerated cocoa beverage powders stored at 25 and 35 °C, in a relative humidity of 84%,was also monitored, in order to simulate hot and humid climates (like northern Brazil). Overtime, it was observed increase of the repose angles and products darkening. The lecithinated cocoa beverage powder was more susceptible to caking than the steam agglomerated product, with the formation of lumps from the 63th day of storage
Doutorado
Engenharia de Alimentos
Doutora em Engenharia de Alimentos
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Dupas-Langlet, Marina. "De la déliquescence au mottage des poudres cristallines : cas du chlorue de sodium." Thesis, Compiègne, 2013. http://www.theses.fr/2013COMP2094/document.
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Le mottage ou l’agglomération non désirée des cristaux déliquescents est un phénomène récurrent dans l’industrie, notamment au cours du transport et du stockage. Les variations des conditions environnantes sont fréquemment responsables de la dégradation de ce type de poudres. En particulier, les fluctuations de l’humidité ambiante conduisent à la formation d’une solution saturée par déliquescence du solide puis à la formation de ponts solides par évaporation de l’eau. Dans cette étude, on se concentre sur le chlorure de sodium. L’équilibre avec la vapeur d’eau et les cinétiques de prise et perte en eau sont analysés et reliés au comportement mécanique macroscopique des cristaux. Le contact avec des cristaux de différente nature tels que le sucrose met en évidence le phénomène de déliquescence mutuelle. Le modèle des solutions régulières appliqué aux systèmes ternaires comportant du NaCl, du sucrose et de l’eau permet de mieux comprendre la chute de déliquescence. La présence des molécules d’eau à la surface des cristaux et la condensation capillaire à faible humidité relative provoque la déliquescence de NaCl et du sucrose simultanément. L’évaporation de l’eau et la recristallisation des cristaux à partir de la solution ainsi formée sont inhibées, en particulier à la composition solide du point eutonique. Le comportement singulier à cette composition qui s’apparente à celui d’un corps pur montre une recristallisation partielle du mélange "eutonique" associée à la formation d’une phase amorphe dans les conditions de l’expérimentation. Afin d’éviter le renforcement au mottage, l’étude de différents agents anti-mottants révèle l’efficacité du stéarate de magnésiumCaking or undesired agglomeration of deliquescent crystals is a recurrent phenomenon in industry, especially during transportation and storage. The variation of environmental conditions is often pointed out as a cause of the degradation of this kind of powders. More precisely, the fluctuations of ambient humidity lead to the formation of a saturated solution by deliquescence followed by the formation of solid bridges when water evaporates. Sodium chloride is chosen as a model substance in this study. The equilibrium with water vapor and the kinetics of water uptake and loss are analyzed and related to the mechanical macroscopic behavior of crystals. The contact with crystals of different nature such as sucrose highlights the phenomenon of mutual deliquescence. The model of regular solutions applied to ternary systems containing NaCl, sucrose and water allows a better understanding of deliquescence lowering. The presence of water molecules and capillary condensation at low relative humidity lead to the deliquescence of NaCl and sucrose simultaneously. Water evaporation and recrystallization of solid from such solution is compromised, especially at the solid composition of the “eutonic point”. The singular behavior at this composition which resembles to the one of a pure substance shows a partial recrystallization of the “eutonic” mixture and the formation of an amorphous phase under the experimental conditions applied. In order to avoid caking reinforcement, the study of differentanti-caking agents reveals the efficiency of magnesium stearate
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Brech, Michael. "Development of in-situ coated lactose particles during spray drying." Thesis, University of Canterbury. Chemical and Process Engineering, 2014. http://hdl.handle.net/10092/9998.
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Lactose is used in many food/pharmaceutical products, despite powders containing amorphous lactose being difficult to handle because they tend to be sticky and are prone to crystallization and powder caking. There is therefore a market for lactose powder with improved functionality to facilitate powder handling. The aim of the proposed project was to produce a value-added, free-flowing and non-caking lactose powder that can be easily blended into other dairy products, such as dry-powder soups or drinks, and non-dairy products such as chocolate bars. The principle of particle coating during spray drying (in-situ coating), which exploits the phenomenon of solute segregation of different components within the drying droplet, was used for the purpose of producing such powders. In this work, spray-dried lactose powders containing low concentrations of edible additives, such as proteins, polymers or fat, were produced in order to investigate the ability of these additives to accumulate at the droplet surface during drying to form a coating that improves powder functional properties and limits powder caking. This thesis presents the results of the trials necessary to develop these coated powder by the use of an
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Carpin, Mélanie. "Le mottage du lactose : Compréhension des mécanismes et prévention." Thesis, Rennes, Agrocampus Ouest, 2018. http://www.theses.fr/2018NSARB309/document.
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L’augmentation de la demande en lait infantile génère une forte croissance de la production mondiale de lactose. En raison d’exigences accrues sur la qualité du produit, le mottage, ou prise en masse spontanée de la poudre, est une non-conformité pouvant s’avérer très coûteuse. En utilisant une approche procédé – produit, ce projet vise à identifier les paramètres critiques et comprendre les mécanismes de mottage du lactose, pour donner les moyens aux industriels de prévenir le mottage. Les résultats obtenus sur des poudres produites à l’échelle pilote montrent le rôle déterminant des impuretés (i.e. composés autres que le lactose) et de la granulométrie. En effet, les impuretés renforcent l’hygroscopicité et le mottage. De plus, en augmentant la teneur en impuretés, la surface spécifique et le nombre de points de contact, une diminution de la taille des particules et une hétérogénéité de tailles accrue intensifient le mottage. L’analyse des poudres commerciales a confirmé ces résultatUn autre résultat marquant de ce travail est le développement d’un test de mottage accéléré, qui permet de classer des poudres de lactose en fonction de leur tendance au mottage en moins d’une journée, après un stockage à 50°C et 60% d’HR. Un test similaire implémenté sur chaque site de production permettrait l’identification rapide des lots à risque avant expédition. Grâce à la meilleure compréhension des mécanismes de mottage fourni par ce travail, les industriels peuvent cibler les étapes critiques du procédé à optimiser pour prévenir le mottage du lactoseDriven by the growth in the infant formula market, lactose production is increasing worldwide, and the requirements for the product quality are becoming stricter. Caking, or the unwanted agglomeration of lactose powder particles, is synonym of poor quality for the customers and should therefore be prevented to avoid large economic loss. Focusing on the process–product relationship, this PhD project aimed at finding the critical parameters and understanding the caking mechanisms in lactose powder in order to establish means to limit caking. In samples from pilot production, impurities (i.e. non-lactose components) were shown to increase moisture sorption and caking. The particle size distribution of the powder also exhibited a large effect on caking. Indeed, smaller particles and a broader distribution were characterized by enhanced moisture sorption and stronger caking, which were explained by a larger impurity content and surface area and more contact points.Analyses on the commercial powder confirmed these results and revealed the instability of the water activity during storage of the powder after drying, which was linked to caking in the bags. This PhD project also addressed an essential need in the dairy industry, i.e. the development of an accelerated caking test. Samples from different production sites were discriminated in terms of caking in less than a day, using appropriate test conditions (50°C and 60% RH). A similar test implemented at all sites would highlight batches with a high caking tendency before shipment to the customers. The better understanding of th
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Le, Brun Olivier. "Contribution à l'étude du mottage et de la conservation des additifs de panification pulvérulents à base d'esters diacetyltartriques de mono- et diglycerides (DATEM, E 472°)." Vandoeuvre-les-Nancy, INPL, 2004. http://www.theses.fr/2004INPL033N.
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Bien que souvent incontournable, l'incorporation de DATEM dans des mélanges pulvérulents tels que les améliorants de panification, s'avère problématique. Les DATEM sont en effet des produits délicats à conserver car ils mottent lorsqu'ils sont soumis à des contraintes de température, d'humidité ou de tassement. Les essais de conservation réalisés au cours de cette étude montrent cependant que la température est le plus perturbant de ces trois facteurs. Les DATEM sont en effet composés majoritairement de corps gras. Lorsque la température s'élève, ces corps gras fondent et forment une sorte de "ciment" liquide qui agglomère les autres particules du mélange. Lorsque la température s'abaisse, le "ciment" durcit, transformant le mélange pulvérulent de départ en blocs durs et compacts. Les essais menés lors de la phase d'optimisation des formulations montrent par ailleurs que si la dureté des blocs obtenus dépend de la température de conservation, elle dépend également de la composition des mélanges : origine et taux d'incorporation des DATEM, nature des ingrédients associés aux DATEM, utilisation éventuelle d'agents anti-agglomérants. Une méthode originale, basée sur le calcul d'un Indice de Résistance au Mottage (ou IRM) a donc été développée pour classer et sélectionner les DATEM (ou plus exactement les couples DATEM / agents de charge) en fonction de leur aptitude à résister aux fortes températures. Il est enfin important de noter que cette étude relative au mottage des améliorants de panification a nécessité la mise au point de plusieurs techniques de quantification du mottage (analyse sensorielle, analyse pénétrométrique et tamisage), toutes parfaitement corréléesThe incorporation of diacetyltartric esters of monoglycerides (DATEM) in powder blends, such as bread-making improvers, is often necessary and seems to be problematic. Ln fact, it is difficult to preserve DATEM from caking once they are exposed to temperature, humidity or compressing constraints. The present study showed that the temperature is the most influencial parameter on caking phenomenon during the powder preserving. This can be explained by the fact that DATEM are mainly composed by fats which melt with increasing temperature. "Liquefied" fats bind together the other particles of powder blend and then harden when temperature decreases, leading to the formation of bard and compact blocks. Different assays done on the optimisation of blend formulation show that the hardness of the formed blocks depends on the preserving temperature and even on the mixture composition : origin and incorporating rate of DATEM, nature of ingredients mixed with DATEM, the use of anticaking agents. A new method based on the determination of the Index of Resistance to Caking, was developed to classify and select "DATEM / excipient" mixtures according to their resistance to high temperatures. It is also important to note that the present study on the caking phenomenon of bread-making improvers required the development of different techniques of caking quantification (such as sensory anaIysis, penetrometry and sieving), closely connected
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Mosquera, Mosquera Luz Hicela. "INFLUENCIA DE LA HUMEDAD Y DE LA ADICIÓN DE SOLUTOS (MALTODEXTRINA O GOMA ARÁBIGA) EN LAS PROPIEDADES FISICOQUÍMICAS DE BOROJÓ Y FRESA EN POLVO." Doctoral thesis, Universitat Politècnica de València, 2010. http://hdl.handle.net/10251/9035.
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Tanto la liofilización como el secado por atomización ofrecen una evidente ventaja en la obtención de productos con bajos contenidos de humedad y alta calidad sensorial, nutritiva y funcional. Sin embargo, los productos pulverizados presentan una gran disposición a sufrir cambios en sus propiedades físicas por efecto del ambiente y del tiempo. Estos cambios están asociados a la ganancia de agua y su efecto en el estado físico del producto. La alta higroscopicidad característica de los productos en polvo obtenidos a partir de zumos de frutas ha generado la necesidad de utilizar solutos de alto peso molecular que actúen como barrera en los procesos de adsorción de agua. En el presente trabajo se obtuvieron y modelizaron las isotermas de sorción y la relación temperatura de transición vítrea (Tg) - humedad de dos maltodextrinas (4-7 y 16-19 dextrosa equivalente) y goma arábiga, las cuales desde el punto de vista termodinámico, resultaron ser adecuadas para actuar como hidrocoloides estabilizadores en la obtención de productos de baja humedad. Por otra parte, se analizó la composición de la pulpa de borojó y fresa utilizada para la obtención de productos en polvo. La pulpa de ambas frutas fue liofilizada con y sin la adición de los solutos caracterizados y acondicionada a diferentes niveles de humedad relativa. A todas las muestras se les analizó la Tg, las propiedades mecánicas y el color. Además se estudió la solubilidad de las muestras en polvo obtenidas. Los análisis de Tg, propiedades mecánicas y color se llevaron a cabo también en productos comerciales de borojó atomizado con y sin maltodextrina 20 dextrosa equivalente añadida. Los resultados permiten concluir que el parámetro que define la pérdida de calidad de los productos de fruta en polvo estudiados por efecto de su humectación es el cambio en sus propiedades mecánicas, relacionado con el inicio de los fenómenos de apelmazamiento. Estos cambios ocurren en las muestras desde el momento
que se inicia la transición vítrea y se dan antes que los cambios de color
que pueden asociarse al pardeamiento de las muestras. Desde este punto
de vista, los bajos valores de humedad y actividad del agua crítica de las
muestras sin solutos, hace recomendable la incorporación de compuestos
de alto peso molecular. De los diferentes solutos considerados en este
estudio, la goma arábiga sería el recomendado para este fin.Mosquera Mosquera, LH. (2010). INFLUENCIA DE LA HUMEDAD Y DE LA ADICIÓN DE SOLUTOS (MALTODEXTRINA O GOMA ARÁBIGA) EN LAS PROPIEDADES FISICOQUÍMICAS DE BOROJÓ Y FRESA EN POLVO [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/9035
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Samain, Sophie. "Caractérisation multi-échelle de l’efflorescence et du mottage du saccharose." Electronic Thesis or Diss., Compiègne, 2017. http://www.theses.fr/2017COMP2371.
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Le mottage, ou agglomération non-désirée, est un phénomène qui dégrade la qualité des poudres, notamment leur coulabilité. Il constitue donc une problématique majeure dans l’industrie. Dans le cas des composés cristallins hydrosolubles, les fluctuations d’humidité ambiante sont responsables de la succession de phénomènes de déliquescence partielle (formation d’une solution saturée) et d’efflorescence (recristallisation avec évaporation de l’eau) entraînant la formation de ponts liquides puis solides. On s’intéresse ici au cas du saccharose, dont la viscosité élevée de la solution saturée rend le phénomène d’efflorescence complexe car régi par la cinétique de séchage. En première partie, les cinétiques de déliquescence et d’efflorescence sont analysées à l’échelle des particules et les mécanismes gouvernant ces phénomènes, résistances au transfert externe ou interne, sont mis en évidence selon les conditions d’humidité. Dans une seconde partie, une étude à l’échelle macroscopique est réalisée grâce à la conception d’un dispositif de mottage permettant l’obtention d’échantillons mottés de façon rapide et homogène dans des conditions contrôlées. Trois tests mécaniques sont comparés grâce à une méthode statistique de régression linéaire locale selon des critères de sensibilité et de répétabilité. Le test de cisaillement a ainsi été sélectionné et a permis de mettre en évidence l’influence de différents facteurs sur le mottage. Par ailleurs, l’étude de l’ajout de trois composés (NaCl, fructose, maltodextrine DE12) au saccharose a montré une sensibilité accrue à l’humidité, un retard de l’efflorescence et une réduction considérable de la résistance mécaniqueCaking, or undesired agglomeration, is a phenomenon jeopardizing powders’ quality, in particular their flowability. It is therefore a main issue for industry. In the case of water-soluble crystalline materials, humidity fluctuations cause a series of phenomena, partial deliquescence (formation of a saturated solution) and efflorescence (recrystallization with water evaporation) leading to the formation of liquid then solid bridges. This study focuses on the case of sucrose. Because of the highly viscous saturated solution, the efflorescence phenomenon is governed by the drying kinetics which makes it complex. In the first part, the kinetics of deliquescence and efflorescence were analyzed at the scale of the particles and the governing mechanisms, resistances to external or internal mass transfer, were identified according to the humidity conditions. In a second part, a macroscopic study was conducted. First, a caking device allowing homogeneous caked samples to be quickly obtained in controlled conditions was developed. Three mechanical tests were compared on the basis of sensitivity and repeatability through a statistical method, the local linear regression. The shear test was found to be the best approach and was used to study the influence of several factors on sucrose caking. Besides, the addition of three components (NaCl, fructose, DE12 maltodextrin) to sucrose showed a higher sensitivity to humidity, a delay in efflorescence and a significant decrease of the mechanical resistance
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Bonnin, Delphine. "Régulations cellulaires et métaboliques de l'halophyte cakile maritima en réponse au sel." Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7004.
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La salinisation des sols est une problématique croissante de nos jours. Elle se produit le plus souvent dans des régions arides et semi-arides du fait de mauvaises pratiques de l’irrigation. Cette salinisation entraine une réduction du rendement de 30 % voire rend les terres incultivables. En 2014, la perte financière due à la salinisation a été estimée à 27,3 milliards de dollars. Les travaux de cette thèse s’intéressent à une plante résistante au sel : Cakile maritima. Il s’agit une halophyte facultative, c’est-à-dire qu’elle est capable de réaliser son cycle de vie dans des sols comprenant de 0 à 500 mM NaCl. Ces travaux ont porté sur les mécanismes de gestion du sel au niveau cellulaire ; nous avons ainsi mis en évidence chez cette plante le fonctionnement du système Salt Overly Sensitiv (SOS) déjà décrit chez la plante modèle Arabidopsis thaliana. Son déclenchement semble lié à une production d’oxygène singulet entrainant un influx de calcium qui va ensuite activer le système SOS menant à l’exclusion du Na+ de la cellule via l’antiport Na+/H+ SOS1. Ce mécanisme d’exclusion du sel participe à l’adaptation au sel menant à la survie, et fait le pendant avec la voie conduisant à une mort cellulaire programmée que nous avons précédemment décrite chez C. maritima. Dans un second temps, nous nous sommes intéressé au métabolisme de C. maritima en réponse à une exposition au sel modérée (100mM NaCl) ou forte (400mM NaCl). Nous avons pu mettre en évidence qu’une exposition au sel modérée entraine peu de changements du métabolisme chez C. maritima même si celui-ci commence à s’amorcer au bout de 20 jours de traitement. En revanche, un traitement salin fort entraine dès 10 jours de forts changement métaboliques. Ainsi, nous avons observé une diminution des sucres et des acides organiques quand les acides aminés sont accumulés. Ces résultats nous ont permis de détecter les voies métaboliques les plus touchées par un traitement salin fort. Le cycle de Krebs et le métabolisme du galactose sont impactés négativement quand la synthèse des acides aminés et la photorespiration sont impactés positivement. Enfin, ce travail de thèse a également été l’occasion de s’intéresser à la potentielle implication de l’hétérophyllie de développement de C. maritima dans sa résistance au sel. Les résultats nous ont montré une accumulation différentielle du Na+ dans les feuilles en fonction du niveau foliaire ainsi qu’une mort cellulaire également différentielle. L’ensemble de ce travail sur l’halophyte C. maritima montre à la fois l’universalité d’une partie des mécanismes de gestion du sel chez les plantes mais également les spécificités de réponses qui souligne la capacité d’adaptation des halophytesSoil salinization is a growing problem nowadays. It occurs most often in arid and semi-arid regions due to poor irrigation practices. This salinization leads to a 30% reduction in yield and even makes the land unusable. In 2004, the financial loss due to salinization was estimated at $27.3 billion. The work of this thesis focuses on a salt-resistant plant: Cakile maritima. It is an optional halophyte, i.e. it is capable of performing its life cycle in soils containing 0 to 500 mM NaCl. This work focused on salt management mechanisms at the cellular level; we have thus demonstrated in this plant the functioning of the Salt Overly Sensitiv (SOS) system already described in the model plant Arabidopsis thaliana. Its activation seems to be linked to a singulet oxygen production leading to an influx of calcium, which will then activate the SOS system leading to the exclusion of Na+ from the cell via the antiport Na+/H+ SOS1. This salt exclusion mechanism participates in the adaptation to salt leading to survival, and parallels the pathway to programmed cell death that we previously described in C. maritima. In a second step, we investigated the metabolism of C. maritima in response to moderate (100mM NaCl) or high (400mM NaCl) salt exposure. We have been able to demonstrate that moderate salt exposure causes few changes in metabolism in C. maritima even if it begins after 20 days of treatment. On the other hand, a strong saline treatment leads to strong metabolic changes after 10 days. Thus, we have observed a decrease in sugars and organic acids when amino acids are accumulated. These results allowed us to detect the metabolic pathways most affected by strong saline treatment. The TCA cycle and galactose metabolism are negatively impacted when amino acid synthesis and photorespiration are positively impacted. Finally, this thesis work was also an opportunity to examine the potential involvement of heterophyllous development of C. maritima in its salt resistance. The results showed us a differential accumulation of Na+ in the leaves as a function of leaf level as well as a differential cell death. All this work on the halophyte C. maritima shows both the universality of some of the mechanisms for salt management in plants and the specificities of responses that underline the adaptability of halophytes
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Ben, hamed Ibtissem. "Réponses cellulaires rapides de l’halophyte Cakile maritima au choc salin : analyse de leur implication dans la mort cellulaire programmée et l’adaptation." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS444.
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Les travaux présentés dans cette thèse ont porté sur la specificité des réponses cellulaires de l’halophyte obligatoire Cakile maritima au choc salin et la régulation des événements précoces impliqués dans la mort cellulaire programmée et la survie en condition de salinité. Dans une première étape, nous avons montré que cette plante est aussi tolérante aux chocs salins répétés qu’au stress salin progressif. Cependant, on a observé de zones de mort cellulaires sur les feuilles âgées soumises à un choc salin sévère (400 mM NaCl). Pour mieux cerner la cascade d’événements impliqués dans ce processus de mort cellulaire, nous avons poursuivi nos expériences sur des suspensions cellulaires de C. maritima, dont nous avons-nous même optimisé les conditions d’obtention, et des suspensions cellulaires d’Arabidopsis thaliana (glycophyte modèle). Chez les deux espèces, nous avons observé une mort cellulaire programmée qui dépend de la durée et l’intensité du traitement salin appliqué, et qui met en jeu les mêmes événements cellulaires notamment la dépolarisation de la membrane plasmique due à l’entrée de Na+ par les NSCCs, un dysfonctionnement mitochondrial, une production d’anions superoxydes et une activation de protéines de type caspase. La tolérance de C. maritima au stress salin serait potentiellement due à une forte accumulation d’ascorbate qui permettrait à cette halophyte de mieux réduire les dommages générés par le stress oxydatif. C. maritima s’est aussi distinguée par une meilleure capacité de contrôler l’accumulation cytoplasmique de Na+, conduisant à la survie de ses cellules en condition de salinité. Cette étude sur la mort cellulaire induite par le NaCl chez les cellules en culture de C. maritima nous a aussi permis de mettre en évidence deux types de comportement dans cette population de cellules en culture : l’un lié à une dépolarisation soutenue en réponse au NaCl conduisant probablement à la mort de ces cellules, l’autre lié à une dépolarisation transitoire indiquant que l’influx de Na+ au travers des NSCC était régulé permettant probablement aux cellules présentant ce comportement de survivre en évitant l'accumulation excessive de Na+ dans le cytosol. Dans la dernière partie de ce travail, nous avons mis en évidence la capacité de C. maritima d’exclure Na+ via le système SOS. Ce résultat suggère l’existence d’une deuxième voie de signalisation induite parallèlement à celle conduisant à la mort cellulaire. Cette voie, impliquant une production rapide d’oxygène singulet, pourrait permettre un influx de Ca2+ dans le cytoplasme activant la protéine SOS3 et en cascade SOS2 et SOS1 et les H+-ATPases de la membrane plasmique permettant un efflux du Na+ via SOS1 hors des cellulesAbstractThis work aimed at understanding the specificity of cellular responses of the obligate halophyte Cakile maritima to salt shock and regulation of early events involved in programmed cell death and survival under salinity conditions. In a first step, we have shown that this plant is tolerant upon both repetitive salt shocks and gradual salt application. However, we have observed a cell death zones on older leaves subjected to a severe shock saline (400 mM NaCl). To better understand the cascade of events involved in the cell death process, we continued our experiments on suspension culture of C. maritima, which we have optimized ourselves the conditions for establishment and suspension culture of Arabidopsis thaliana (glycophyte model). In both species, salinity induced programmed cell death that depends on the duration and the intensity of the applied salt treatment. Also, the same cellular events, including depolarization of the plasma membrane due to the Na+ influx by NSCCs, mitochondrial dysfunction, production of superoxide anions and activation of caspase-like proteins, occurs early in response to salt stress. C. maritima tolerance to salt stress is potentially due to a strong accumulation of ascorbate that would allow this halophyte to better reduce damage generated by oxidative stress. C. maritima is also distinguished by a better ability to control the cytoplasmic accumulation of Na+, leading to the survival of its cells under salinity conditions. This study on cell death induced by NaCl in cell culture of C. maritima also allowed us to identify two types of behavior in this population of cells in culture: one related to a sustained depolarization in response to NaCl probably leading to death of these cells, the other linked to a transient depolarization indicating that the Na+ influx through the NSCC was probably regulated allowing cells exhibiting this behavior to survive by avoiding excessive accumulation of Na+ in the cytosol. In the last part of this work, we have demonstrated the ability of C. maritima to exclude Na+ via the SOS system. This result suggests the existence of a second signaling pathway induced in parallel to that leading to cell death. This pathway, involving a rapid production of singlet oxygen, could allow a Ca2+ influx in the cytoplasm that acts as an elicitor for activation of SOS3 protein and SOS2-SOS1 cascade and H+- ATPases of the plasma membrane allowing Na+ efflux via SOS1 out of cells
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Westberg, Erik Daniel. "European phylogeography of the coastal plants Cakile maritima Scop. (Brassicaceae) and Eryngium maritimum L. (Apiaceae)." [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975974033.
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Saka, Ceyda Cakan [Verfasser]. "Die Therapieoption der chronischen Analfissur : eine retrospektive multicentrische Studie / Ceyda Cakan Saka." Gießen : Universitätsbibliothek, 2014. http://d-nb.info/1068825049/34.
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Cakir, Bertan Deniz [Verfasser]. "Bedeutung der elektiven Neck dissection für die Therapie des Oropharynxkarzinoms / Bertan Deniz Cakir." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2014. http://d-nb.info/106027700X/34.
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Cakir, Meliha [Verfasser], and Florian [Akademischer Betreuer] Haller. "Das Kolorektale Karzinom: Molekularzytogenetische Untersuchungen von Kolon- und Rektumkarzinomen / Meliha Cakir. Betreuer: Florian Haller." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2010. http://d-nb.info/1044993707/34.
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Cakir, Halil [Verfasser], and Zoltán [Akademischer Betreuer] Harman. "Quantum Electrodynamic Theory of Few-Electron Highly Charged Ions / Halil Cakir ; Betreuer: Zoltán Harman." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1213902452/34.
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Cakir, Bayram [Verfasser], Wolfram [Gutachter] Sander, Martin [Gutachter] Feigel, and Martina [Gutachter] Havenith. "Matrixisolation und IR-spektroskopische Charakterisierung fluorierter Dehydrophenylnitrene / Bayram Cakir ; Gutachter: Wolfram Sander, Martin Feigel, Martina Havenith ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2011. http://d-nb.info/1204256446/34.
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SHIM, BONG-SUP. "Les pronoms coreens o, kio et caki dans la phrase et dans le discours : essai de grammaire comparee." Paris 8, 1991. http://www.theses.fr/1991PA080598.
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Cette etude a pour but de decrire les proprietes syntaxiques, semantiques et interpretatives de trois pronoms coreens : caki, kio et le pronom nul (o). La description est abordee dans une perspective comparative et dans le cadre du modele dut "gouvernement et liage" de la grammaire generative chomskyenne. Les points essentiels de cette etude se resument comme suit : (i) le pronom o est un prono: faible, au meme titre que les clitiques francais; (il) kio qui morphologiquement peut etre decompose en une pro-forme anaphorique (o) et une pro-forme deictique 8ki), pourrait etre compare a ce-lui. . . Ci. Cependant sur une grille scalaire ou les unites seraient placees des plus deictiques aux plus anaphoriques, kio se trouve entre il et celui-ci; (iii) le reflechi caki se laisse identifier comme un pronom a. Neanmoins, les donnees observees au chapitre 4 montrent clairement que decrire ses contraintes uniquement en termes de c-commande ne suffit pas a rendre compte de la distribution de ce pronom. Il est necessaire de recourir a des notions qui ressortissent a la grammaire du discours, comme celles de sujet de conscience et d'empathie. Les resultats obtenus dans cette etude indiquent que l'opposition tracee par la theorie chomskyenne du liage entre pronoms a et pronoms p doit etre decomposee en un ensemble non compact de proprietes syntaxiques et discursivesThe goal of this study is to describe syntactic, semantic and interpretive properties of three korean pronouns : caki, kio, and null pronoun (o). The description is made in the comparative perspective and within the so-called "government and binding" theory developed in chomsky (1981). The main points of this study are resumed as follows : (i) null pronoun (o) may assume the function of french clitics; (ii) kio may be morphologically decomposed into anaphoric pro-form (o9 and deictic pro-form (ki), as french personal pronoun celui-ci (- ce. . . Ci and lui). However, the examination of syntactic and semantic properties of kio shows that this pronoun has intermediate character between il and celui-ci (iii) caki is anaphor. The data presented in chapter 4 show clearly that the structural constraints as c-command are not sufficient for complete description of the distribution of caki, and that the appeal to the notions like "subject of consciousness" and "empathy" is necessary. The results achieved in this study indicate that the opposition between anaphors and pronominals, traced by binding thoery, must be reconsidered and decomposed into a non-compact whole of syntactic and non-syntactic propreties
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Meot, Duros Laetitia. "Osmorégulation et production de molécules actives chez des halophytes du littoral breton." Brest, 2009. http://www.theses.fr/2009BRES2007.
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Le littoral est un milieu fragile menacé notamment par l’érosion, laquelle est accentuée par l’activité anthropique. Il est donc important de connaître et de protéger les peuplements végétaux y vivant. Cette étude s’est intéressée à trois halophytes communes des côtes bretonnes (la criste marine ou Crithmum maritimum L, la roquette de mer ou Cakile maritima Scop. Et le chardon des dunes ou Eryngium maritimum L. ), en mettant tout d’abord en évidence leurs stratégies osmoadaptatives. Ces trois espèces, bien que vivant au même niveau de l’estran, ne réagissent pas de la même façon face aux facteurs environnementaux. Ainsi, la roquette de mer accumule du sodium et de la proline, tandis que le chardon des dunes s’est adapté anatomiquement grâce à son épaisse cuticule recouvrant ses feuilles et limitant la déshydratation. Enfin, la criste marine est une halophyte facultative sans stratégie métabolique particulière, adaptant la forme de ses organes aériens au niveau de stress subi. Une attention a également été portée sur les teneurs en composés phénoliques et l’activité antioxydante de ces plantes, révélant notamment l’abondance de l’acide chlorogénique dans les feuilles de criste marine. Les plantes se distinguent principalement grâce leur activité antiradicalaire différente. Enfin, une étude a été menée sur les activités antimicrobiennes des plantes, l’attention étant portée sur des microorganismes intervenant dans l’agroalimentaire et la cosmétique. Ce travail a conduit, chez la criste marpe, à l’isolement et à la mise en évidence de nouvelles activités antibactériennes et cytotoxique du falcarindiol. Le potentiel de valorisation de chacune des 3 espèces est discutéCoastline is a fragile environment, notably threatened by erosion which is increased by anthropic activity. Thus, it is important to better know and protect coastal populations living in that habitat. This study was conducted in three halophytes commonly found on Brittany coasts (sea fennel or Crithmum maritimum L. , sea rocket or Cakile maritima Scop. And sea holly or Eryngium maritimum L. ), to highlight their osmoadaptative strategy. Although living in the same environment (coastal dunes), these three species don’t exhibit similar metaboli responses to abioticfactors. Thus, sea rocket accumulates sodium and proline in its leaves, whereas sea holly has a morphological adaptation, as seen by its thick cuticle which covers its leaves and limits water loss. Sea fennel is a facultative halophyte without particula metabolic response to stress, only adapting its aerial biomass production to stress level. Attention was also given to phenolic contents an antioxidant activities of the plants, revealing the abundance of chlorogenic acid in sea fennel leaves. Lnterestingly, although exhibiting different levels of radical scavenging activity, the three studied species showed a similar antioxidant capacity. A study of antimicrobial activities of those halophytes, focused on potential food or cosmetics contaminants, led to the isolation and the demonstration of new antibacterial and cytotoxic properties of falcarindiol in sea fennel
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Listiohadi, Yuanita D., University of Western Sydney, of Science Technology and Environment College, and of Science Food and Horticulture School. "The caking of lactose." 2004. http://handle.uws.edu.au:8081/1959.7/25753.
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This project has investigated the mechanism of caking of lactose and identified some possible solutions to minimise caking of lactose and dairy powders, additional to those suggested in the literature. A background to lactose and caking is given. The problems of caking are identified and discussed. The project adds information to the knowledge on the polymorphic forms of lactose and their inter-relationships due to moisture sorption and processes such as milling. This information and many others in the literature are used to complete the simplified lactose conversion diagram developed by King [1965] and improved by Walstra, et al. [1999], which has been widely used in the literature as a guide for lactose manufacturing, processing, and storage.Doctor of Philosophy (PhD)
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Rodrigues, Ana Rita da Silva Amorim Gomes. "Development of anti-caking and anti-dust coatings for fertilizers." Master's thesis, 2013. https://repositorio-aberto.up.pt/handle/10216/97739.
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Rodrigues, Ana Rita da Silva Amorim Gomes. "Development of anti-caking and anti-dust coatings for fertilizers." Dissertação, 2013. https://repositorio-aberto.up.pt/handle/10216/97739.
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Coetzee, Sansha. "The caking and swelling of South African large coal particles / Sansha Coetzee." Thesis, 2015. http://hdl.handle.net/10394/15167.
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The swelling and caking propensity of coals may cause operational problems such as
channelling and excessive pressure build-up in combustion, gasification and specifically in fluidised-bed and fixed-bed operations. As a result, the swelling and caking characteristics of certain coals make them less suitable for use as feedstock in applications where swelling and/or caking is undesired. Therefore, various studies have focused on the manipulation of the swelling and/or caking propensity of coals, and have proven the viability of using additives to reduce the swelling and caking of powdered coal (<500 μm). However, there is still a lack of research specifically focused on large coal particle devolatilisation behaviour, particularly swelling and caking, and the reduction thereof using additives. A comprehensive study was therefore proposed to investigate the swelling and caking behaviour of large coal particles (5, 10, and 20 mm) of typical South African coals, and the influence of the selected additive (potassium carbonate) thereon. Three different South African coals were selected based on their Free Swelling Index (FSI): coal TSH is a high swelling coal (FSI 9) from the Limpopo province, GG is a medium swelling coal (FSI 5.5-6.5) from the Waterberg region, and TWD is a non-swelling coal (FSI 0) from the Highveld region. Image analysis was used to semi-quantitatively describe the transient swelling and shrinkage behaviour of large coal particles (-20+16 mm) during lowtemperature devolatilisation (700 °C, N2 atmosphere, 7 K/min). X-ray computed tomography and mercury submersion were used to quantify the degree of swelling of large particles, and were compared to conventional swelling characteristics of powdered coals. The average swelling ratios obtained for TWD, GG, and TSH were respectively 1.9, 2.1 and 2.5 from image analysis and 1.8, 2.2 and 2.5 from mercury submersion. The results showed that coal swelling measurements such as FSI, and other conventional techniques used to describe the plastic behaviour of powdered coal, can in general not be used for the prediction of large coal particle swelling. The large coal particles were impregnated for 24 hours, using an excess 5.0 M K2CO3 impregnation solution. The influence of K2CO3-addition on the swelling behaviour of different coal particle sizes was compared, and results showed that the addition of K2CO3 resulted in a reduction in swelling for powdered coal (-212 μm), as well as large coal particles (5, 10, and 20 mm). For powdered coal, the addition of 10 wt.% K2CO3 decreased the free swelling index of GG and TSH coals from 6.5 to 0 and from 9.0 to 4.5, respectively. The volumetric swelling ratios (SRV) of the 20 mm particles were reduced from 3.0 to 1.8 for the GG coal, and from 5.7 to 1.4 for TSH. In contrast to the non-swelling (FSI 0) behaviour of the TWD powders, the large particles exhibited average SRV values of 1.7, and was found not be influenced by K2CO3-impregnation. It was found that the maximum swelling coefficient, kA, was reduced from 0.025 to 0.015 oC-1 for GG, and from 0.045 to 0.027 oC-1 for TSH, as a results of impregnation. From the results it was concluded that K2CO3-impregnation reduces
the extent of swelling of coals such as GG (medium-swelling) and TSH (high-swelling),
which exhibit significant plastic deformation. Results obtained from the caking experiments indicated that K2CO3-impregnation influenced the physical behaviour of the GG coal particles (5, 10, and 20 mm) the most. The extent of caking of GG was largely reduced due to impregnation, while the wall thickness and porosity also decreased. The coke from the impregnated GG samples had a less fluid-like
appearance compared to coke from the raw coal. Bridging neck size measurements were performed, which quantitatively showed a 25-50% decrease in the caking propensity of GG particles. Coal TWD did not exhibit any caking behaviour. The K2CO3-impregnation did not influence the surface texture or porosity of the TWD char, but increased the overall brittleness of the devolatilised samples. Both the extent of caking and porosity of TSH coke were not influenced by impregnation. However, impregnation resulted in significantly less and smaller opened pores on the surface of the devolatilised samples, and also reduced the average wall thickness of the TSH coke.
The overall conclusion made from this investigation is that K2CO3 (using solution
impregnation) can be used to significantly reduce the caking and swelling tendency of large coal particles which exhibits a moderate degree of fluidity, such as GG (Waterberg region). The results obtained during this investigation show the viability of using additive addition to reduce the caking and swelling tendency of large coal particles. Together with further development, this may be a suitable method for modifying the swelling and caking behaviour of specific coals for use in fixed-bed and fluidised-bed gasification operations.PhD (Chemical Engineering), North-West University, Potchefstroom Campus, 2015
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White, Rudelle. "Changes in chemical and physical properties of South African caking coals during pyrolysis / Rudelle White." Thesis, 2015. http://hdl.handle.net/10394/15818.
Full textAbstract:
The plasticity of coal during pyrolysis is of significant importance, since it affects the reactivity, porosity, particle size and the density of the char and thus also the behaviour of the char during further utilisation processes. The main focus of this study was to characterize the chemical and physical changes which the thermally treated coal undergoes, in order to better understand the pyrolysis process of caking and non-caking South African coals. The pyrolysis behaviour of three South African coals with different caking indices was investigated. The coal samples included; (1) Highveld (TWD), a medium rank C coal with a free swelling index (FSI) of 0, (2) Grootegeluk (GG), also a medium rank C coal, with a FSI of 6.5, and (3) Tshikondeni (TSH), a medium rank B coal with the highest FSI of 9. The three coal samples were classified as vitrinite-rich coals consisting of mainly aliphatic structures. Thermogravimetric experiments were used to determine the different temperatures relating to specific percentages of mass loss using set conditions. The pyrolysis process was stopped at various percentages of mass loss (thus at various stages of the reactions) to characterize the chemical structural changes that occurred at the specific mass loss percentages.
The results obtained from characterization analyses indicated that the three coals differ in chemical composition and thus were expected to behave differently during pyrolysis. The coal samples consist of different amounts of macerals and minerals according to X-ray Fluorescence (XRF) and X-ray Diffraction (XRD) analyses. The Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT) results indicated that some of the functional groups within the coal samples evolved with the increase in temperature. The highly caking coal (TSH) exhibited the highest aromaticity and ring condensation. The surface areas were determined by CO2 adsorption and an increase in surface area was observed with an increase in temperature. The surface area of the GG and TSH coal-derived char samples decreased at some stage, which is an indication of thermoplastic behaviour and subsequent swelling of the coal samples. Scanning electron microscopy (SEM) images confirm the plastic stage of caking coals at specific temperatures and volatile matter release via the multiple bubble mechanism. All these results are given and discussed extensively in this dissertation.MSc (Chemistry), North-West University, Potchefstroom Campus, 2015
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Yang, Meng-Ting, and 楊孟婷. "Study on granulation and evaluation of anti-caking technology by the treatments of Goji concentrated extract and binder." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/48695214339861178217.
Full textAbstract:
碩士國立中興大學
食品暨應用生物科技學系所
102
Rich in functional components, one of which is goji polysaccharide, goji is one of the most commonly used Chinese herbal medicine. Healthy food of domestic Chinese gerbil market has the highst proportion, reaching to 37 %. The market of domestic Chinese herbal related product is about 200 to 250billion, and the product value is huge.( Taiwan Industry Economics Services). Due to the scientific development in the field of Chinese medicine, fluid-bed granulation is often used in the production of it. Usually, the production process is: extracting, concentrating, and drying the material into powder. But in this process, goji becomes highly sticky after the extraction, and it becomes difficult to do fluid-bed drying. Moreover, during the process, the carrier pipe clogs, bursts, and eventually fails the granulation. Caking is also common in the final product. In this experiment, I, using goji extract as the material, explore its changes in viscosity and its anticaking effect through model system. The results are as follows: Under the best extraction conditions for goji, that is, 30-minute soaking, 30-minute boiling in 100 ℃, and another 40-minute boiling in 100 ℃ for the boiled goji grain, I mix the goji liquid, which is boiled separately in the above two sessions, concentrate the mixture, and assess the changes in the viscosity of the extract through three different processing operations. Among the three operations, adding NaCl 15%, adjusting PH to 6, and heating it to 95 ℃ makes the minimum viscosity, stickiness, total phenolic compound, and flavonoid compound, while the amount of polysaccharide has no significant difference. This can improve the fluidity of the extract as well as reduce the difficulty in carrying. Giji extract was mixed with 20% of maltodextrin and added to different concentrations of starch and edible gum.
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(9510965), Adrienne Lea Voelker. "Vitamin Stability and Water-Solid Interactions." Thesis, 2020.
Find full textAbstract:
This dissertation investigates two major structure-function relationships important to food science: vitamin stability and water-solid interactions. Thiamine, vitamin B1, is an essential micronutrient in the human diet. While thiamine is found naturally and as a fortification supplement in many foods, it is chemically unstable on exposure to heat and some co-formulated ingredients, with degradation exacerbated in prolonged shelf-life products. The instability of thiamine is a concern for the development of dietary deficiencies, which are prevalent even in developed countries; however, thiamine stability is not widely studied in the food or pharmaceutical industries. Thiamine is commercially available in two salt forms: thiamine mononitrate (TMN) and thiamine chloride hydrochloride (TClHCl). This study focused on documenting the storage stability of thiamine in solution, considering the effects of which commercially available salt form of the vitamin was used, vitamin concentration, pH, and ions present in solution by monitoring chemical stability and degradation kinetics over a 6-month to 1-year period following storage at 25-80ºC, and expanded these studies into food systems (bread doughs). The results from these studies, including the reaction kinetics of thiamine degradation, the degradation pathway, and the sensory impacts of the degradation products formed, especially as affected by pH and food matrix, can be used to improve thiamine stability and delivery in foods.
The studies of water-solid interactions in this dissertation covered two topics: 1) the effects of formulating a variety of food-relevant additives on the crystallization tendency of amorphous sucrose; and 2) the effects of formulation on the moisture sorption behaviors and physical stability of spices, herbs, and seasoning blends. Sucrose lyophiles were co-formulated with a variety of additives and stored at 11-40% relative humidity (RH). The structural compatibility of sucrose with the additive, and related intermolecular interactions, dictated the tendency of the additive to either delay, prevent, or accelerate sucrose crystallization. Spices, herbs, and seasoning blends were exposed to increasing RH (23-75%) and temperature (20-50ºC) to determine the effect of storage and formulation on a variety of physical properties. In general, as complexity of blends increased, physical stability decreased. While this dissertation covers a wide variety of food chemistry and food materials science topics, including vitamin chemical stability, amorphous sucrose physical stability, and moisture sorption behaviors of spices, herbs, and seasoning blends, the findings provide valuable information on the chemical and physical stability of ingredient systems and how the structure-function relationships of the systems can be controlled for optimal ingredient functionality.
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Tseng, Chih-Hao, and 曾志豪. "Study on the conversion of formyl [2.2.1.] bicycliccarbinols to [3.2.1.] bicyclic alcohols." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/cakz7g.
Full textAbstract:
碩士朝陽科技大學
應用化學系碩士班
94
Abstract Bridged bicyclic alcohols are prone to rearrangement to form various bicyclic ketones under appropriate conditions. Interestingly, we have found that some [2.2.1] bicyclic alcohol derivatives, such as compounds 53, 60 and 67, could undergo ring expansion- alkylation reaction to form [3.2.1] bicyclic diols instead of ketones. At first, compounds 53, 60 and 67, was prepared using camphor (1), camphene (2), and norcamphor (3) as the starting materials. The formylsubstituted [2.2.1] bicyclic carbinol ( compounds 53, 60 and 67 ), then, reacted with various Grignard reagents ( RMgX ) and alkyl lithium reagents ( RLi ) , individually. In addition, ( compounds 53, 60 and 67 ) did undergo simple ring expansion reaction in the presence of sodium methoxide or acetic acid. These reactions turned out to be highly chemoselective、stereoselective and regioselective. The mechanism of these reactions will be also discussed.
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Wagner-Cakir, Eveline Maria [Verfasser]. "Intraabdominelle Gewebekonzentration von Ertapenem / Eveline Maria Wagner-Cakir." 2007. http://d-nb.info/997361794/34.
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Westberg, Erik Daniel [Verfasser]. "European phylogeography of the coastal plants Cakile maritima Scop. (Brassicaceae) and Eryngium maritimum L. (Apiaceae) / Erik Daniel Westberg." 2005. http://d-nb.info/975974033/34.
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Willis, Charles George. "The role of dispersal and adaptive divergence in the diversification and speciation of the tribe Brassiceae and genus Cakile." Diss., 2013. http://hdl.handle.net/10161/8059.
Full textAbstract:
Adaptation is central to our understanding of the origin of biological diversity. Yet whether adaptive divergence promotes the formation of new lineages remains poorly understood. My dissertation addresses the role of adaptive divergence in diversification and speciation. I also investigate an alternative mechanism: dispersal, which can promote diversification and speciation through its effects on gene flow and allopatry. To address the role of divergent adaptation and dispersal in the process of diversification, I take an integrated approach, combining both comparative methods with quantitative genetics to characterize patterns of diversification and speciation in the tribe Brassiceae and genus Cakile. I start with a comparative study of the role of dispersal and adaptation in diversification, and then focus on the role of climatic and latitudinal divergence in the processes of adaptive divergence and speciation. In general, I find limited evidence for the role of divergent adaptation in the evolution of intrinsic reproductive isolation. Diversification in the tribe Brassiceae appears to be mediated by dispersal ability, while in the genus Cakile, the evolution of intrinsic reproductive isolation is largely independent of ecological divergence. Thus, while divergent adaptation to novel habitats and climate are likely occurring in Brassiceae, mediated in part by the evolution of long-distance dispersal, the evolution of intrinsic genic reproductive barriers appears to not be influenced by adaptation.
Dissertation
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Khan, Maruf. "Induction of apoptosis and cell cycle arrest in renal carcinoma cells by phenethyl isothiocyanate and the mechanisms involved." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-3411.
Full textAbstract:
Renal Cell Carcinoma (RCC) has low 5 year survival rate and is resistant to radiation and chemotherapy. Phenethyl Isothiocyanate (PEITC) is a naturally occurring phytochemical that has a variety of anti-cancer properties. Here we explore two anti-cancer properties of PEITC: induction of apoptosis and induction of cell cycle arrest in RCC cells and the underlying mechanisms. We used two human RCC cell lines Caki-1 and Caki-2. Survival and cell proliferation was assayed using Calcein AM. Annexin V staining was used to measure apoptosis. Caspase-3/7 induction was measured using a fluorescent substrate. Cell cycle was studied using Propidium Iodide staining. DNA damage was determined using phospho [gamma]-H2AX antibody. Protein expression and phosphorylation was determined using immunoblotting. PEITC significantly reduced survival of Caki-1 and Caki-2 cells and inhibited their proliferation as determined by Calcein AM. 15 and 20 [mu]M PEITC induced apoptosis in both cell lines and induced caspase-3/7 activity. Western blot analysis revealed caspase-8, caspase-9 and Bid cleavage as well as upregulation of the death receptors Fas and DR5. Lower doses (up to 10 [mu]M) arrested Caki-1 cells in G2/M phase, and this was associated with increased p38 and MK2 (Thr334) phosphorylation. The p38 inhibitor SB203850 inhibited this G2 arrest induced by PEITC. 15 and 20 [mu]M PEITC treatment resulted in increased [gamma]-H2AX phosphorylation suggesting DNA damage, but this was completely blocked by caspase inhibitor. In summary, our study shows that PEITC induces apoptosis in Caki-1 and Caki-2 cells by upregulating Fas and DR5 and activating the downstream apoptosis cascade. PEITC does not cause direct DNA damage to the cells; the observed DNA damage is a result of the apoptotic process and is blocked by caspase inhibitor. PEITC induces G2/M arrest in Caki-1 cells and the mechanism involves p38 phosphorylation which activates MK2. Inducing cell cycle arrest and apoptosis may play an important role in the anti-cancer properties of PEITC. Fully understanding the mechanism by which PEITC induces apoptosis and cell cycle arrest in RCC cells may lead to development of novel chemotherapeutic drugs against RCC.text
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Glube, Natalie [Verfasser]. "The potential of the human kidney cell line, Caki-1, as an in vitro screening system for drug interactions with organic cation transporters / Natalie Glube." 2007. http://d-nb.info/986306444/34.
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