O refinamento dos poros, associado à reação pozolânica e ao efeito filer, reduz a permeabilidade do concreto com cinza de casca de arroz (CCA), o que pode antecipar a sua degradação em altas temperaturas. A literatura mostra que o concreto reidratado em água pode recuperar substancialmente a sua resistência inicial, porém, os estudos sobre a reidratação ao ar e sobre a influência do modo de resfriamento na reidratação são escassos. A pesquisa desenvolvida teve como principal objetivo avançar na análise experimental de concretos convencional e com CCA em altas temperaturas e na reidratação. Na etapa exploratória se avaliou a influência da temperatura de exposição, da adição mineral, do ambiente de acondicionamento, da taxa de aquecimento e do tempo de exposição na resistência à compressão e módulo de elasticidade. Na etapa principal se avaliou a influência do modo de resfriamento, da adição e da idade de reidratação na resistência residual. Complementarmente se utilizou o ensaio de velocidade de pulso ultrassônico (VPU) para avaliar o grau de microfissuração e correlacionar a VPU com as propriedades mecânicas residuais. Na etapa exploratória concluiu-se que a adição, a temperatura, a taxa de aquecimento e o tempo de exposição influenciaram significativamente os resultados. O concreto com CCA cristalina apresentou pior desempenho em altas temperaturas. O concreto com CCA amorfa apresentou desempenho ligeiramente inferior ao concreto convencional em 200°C, devido ao efeito da poro-pressão. No entanto, ambas as CCA podem ser alternativas viáveis considerando sustentabilidade. Na etapa principal, o resfriamento brusco com água provocou maior redução na resistência devido aos gradientes térmicos, porém, permitiu maior recuperação logo nos primeiros sete dias de reidratação. Apesar da recuperação parcial, a resistência ao fim de 154 dias foi inferior a 40% do valor inicial. Nas análises térmicas e de DRX foi possível observar nos concretos resfriados com água a recristalização dos aluminatos de cálcio, do C-S-H e da portlandita, em maior grau no concreto convencional. Foi possível observar correlações fortes entre as variáveis de resposta na etapa exploratória, porém, o mesmo não ocorreu na etapa principal, devido à fissuração e presença de água nos poros. / The pore refinement, associated with the pozzolanic reaction and the filler effect, reduces the permeability of blended concrete with rice husk ash (RHA), which can anticipate its degradation at high temperatures. The literature shows that concrete rehydrated with water can recover substantially its initial strength, but studies on rehydration in air and on the influence of the cooling method on rehydration are scarce. The main objective of this research was to evaluate the performance at high temperatures and in rehydration of conventional and blended concretes with RHA. In the exploratory stage, the influence of exposure temperature, mineral admixture, conditioning environment, heating rate and exposure time on residual strength and modulus of elasticity of heated concrete was evaluated. In the main stage, the influence of cooling method, mineral admixture and time of rehydration in an unsaturated environment on residual strength of concrete was evaluated. The ultrasonic pulse velocity test (UPV) was used to evaluate the degree of micro cracking of concrete and to correlate the UPV with residual strength and modulus. In the exploratory stage it was concluded that mineral admixture, temperature, heating rate and time of exposure significantly influenced the results. In general, concrete with partially crystalline RHA presented the worst performance at high temperatures. Concrete with amorphous RHA presented worse performance than conventional concrete only at 200°C, due to the pore-pressure effect. Despite these results, RHA can be a viable option considering sustainability and high temperatures performance. In the main stage, the rapid cooling with water caused a greater reduction in strength, due to thermal gradients, however, caused a greater strength recovery in the first seven days of rehydration. Despite this partial recovery, the final strength of both concretes after 154 days of rehydration was less than 40% of the initial value. In water-cooled concretes thermal and XRD analyzes show recrystallization of the calcium aluminates, C-S-H and portlandite, to a greater degree in conventional concrete. In the exploratory stage it was possible to observe strong correlations between the independent variables; however, the same did not occur in the main stage, due to cracking and to the presence of water in the pores.

Made available in DSpace on 2016-06-02T19:56:39Z (GMT). No. of bitstreams: 1 3124.pdf: 1709285 bytes, checksum: 01aa5e6d0190ca5658a75e9fefae9b2b (MD5) Previous issue date: 2010-05-28 / Financiadora de Estudos e Projetos / The cultivation of pepper is widespread in Brazil since its colonization. This plant, besides being much appreciated in the cuisine has proven pharmacological effects such as lowering cholesterol, inhibiting appetite and the presence of antioxidants such as ascorbic acid and beta-carotene. It is a product whose demand increases every year, but generally still produced handmade diminish the ability of producers to meet the needs of commerce. To contribute to improving the production of pepper dedo-de-moça, it was the behavior of this plant in analyzing the influence of drying process on the nutritional composition and physical qualities of the dried product. For this, drying kinetics were obtained and certain structural properties (apparent density, real density and porosity) as a function of moisture content during drying. Assessing the quality of the final product was performed by quantification of ascorbic acid and study of rehydration. The convective drying and freeze-drying was compared with respect to product quality parameters such as shrinkage, structural properties, vitamin C retention and rehydration characteristics. To describe the kinetics of drying and rehydration were used empirical and semiempirical equations. The characterization of the rehydration process was carried out from the indices that take account of the capacity of water absorption and loss of solutes. The use of seed from the drying of peppers to obtain seedlings was studied by checking the germination through standardized tests. The samples of convective drying at 60 ºC had the best results in terms of nutritional quality, rehydration characteristics and structural properties, comparing with those obtained from freezedrying. In assessing the use of seeds of peppers after processing to obtain new seedlings, the most suitable temperature was 40 oC to cause less damage to germination. / A cultura da pimenta está bem difundida no Brasil desde a sua colonização. Esse vegetal, além de ser muito apreciado na culinária possui efeitos farmacológicos comprovados como o de redutor do colesterol, inibidor do apetite e a presença de substâncias antioxidantes como o ácido ascórbico e o beta-caroteno. É um produto cuja demanda aumenta a cada ano, mas que a forma como é produzido continua, em sua maioria, artesanal diminuindo a capacidade dos produtores de atender às necessidades do comércio. Visando contribuir para o melhoramento da produção da pimenta dedo-de-moça, verificou-se o comportamento desse vegetal na secagem analisando a influência do processo na composição nutricional e qualidades físicas no produto seco. Para isso, foram obtidas as cinéticas de secagem e a determinação das propriedades estruturais (densidade aparente, densidade real e porosidade) em função do teor de umidade durante a secagem. A avaliação da qualidade do produto final foi realizada pela quantificação de ácido ascórbico e estudo da reidratação. A secagem convectiva foi comparada com a secagem em liofilizador com relação a parâmetros de qualidade do produto como encolhimento, propriedades estruturais, retenção de vitamina C e características de reidratação. Para descrever a cinética de secagem e de reidratação foram utilizados modelos empíricos e semi-empíricos. A caracterização do processo de reidratação foi realizada a partir dos índices que levam em conta a capacidade de absorção de água e a perda de solutos. Avaliou-se também o aproveitamento das sementes resultantes do processamento para obtenção de novas mudas através da verificação da capacidade germinativa por meio de testes padronizados. As amostras obtidas da secagem por convecção a 60oC tiveram os melhores resultados em termos de qualidade nutricional, características de reidratação e propriedades estruturais, comparando-se com aquelas obtidas da liofilização. Na avaliação do uso das sementes após o processamento das pimentas para obtenção de novas mudas, a temperatura mais adequada foi de 40oC por causar menos prejuízo a capacidade germinativa.

Made available in DSpace on 2015-03-26T13:36:38Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2386385 bytes, checksum: 37df64ce6a5f35ae5e5b5a62e4fc9660 (MD5) Previous issue date: 2009-02-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work had the goals to evaluate the effect of dry storage on the obstruction and rehydration of the flowers of Epidendrum ibaguense Kunth, evaluate the influence of cutting in the rehydration and vase life of flowers after dry storage, evaluate the effects of the use of different solutions on the vase life of inflorescences submitted or not submitted to prior to dry storage, evaluate the influence of temperature and dry storage and the postharvest in the quality flowers previously treated and untreated with silver thiosulfate (STS). Cut flowers of E. ibaguense can be dry stored up to 24 hours, without occuring reduction of the vase life and loss of commercial quality. After the dry storage, there is absorption of water even without proceding the cut of the stem base. However, extention of the vase life was observed with the cut of the base of the stem 1,0 cm height. To prolong the life of vase of E. ibaguense in both flower submitted to the water deficit, pulsing the stems with 2,0 mM of STS by 30 minutes is highly recommended. To preserve the flowers of E. ibaguense that need to be transported or dry stored , pulsing is recommended at concentration of 2,0 mM STS for 30 minutes, followwed storage at 10 ºC for a maximum period of 4 days. / Este trabalho teve como objetivos avaliar o efeito do armazenamento a seco na obstrução e reidratação de inflorescências de Epidendrum ibaguense Kunth; avaliar a influência do corte na reidratação e vida de vaso das flores após o armazenamento a seco; determinar os efeitos do uso de diferentes soluções sob a vida de vaso de inflorescências submetidas ou não submetidas previamente ao armazenamento a seco; avaliar a influência da temperatura e do armazenamento a seco, na qualidade pós-colheita de flores tratadas e não tratadas previamente com tiossulfato de prata (STS). Flores cortadas de Epidendrum ibaguense KUNTH podem ser armazenadas a seco por até 12 horas, sem que ocorra redução da vida de vaso e perda da qualidade comercial. Após o armazenamento a seco ocorre absorção de água mesmo sem realização do corte da base. Contudo, um prolongamento da vida de vaso é observado com a realização do corte da base da haste, a partir de 1,0 cm. Para prolongar a vida de vaso de flores de E. ibaguense submetidas ou não ao déficit hídrico, recomenda-se o pulsing das hastes florais em 2,0 mM de STS, por 30 minutos. Para conservar as flores de E. ibaguense que necessitem ser transportadas ou armazenadas a seco, recomenda-se pulsing com STS 2,0 mM, por 30 minutos, seguido de armazenamento a 10ºC, permanecendo nesta condição por até 4 dias.

O refinamento dos poros, associado à reação pozolânica e ao efeito filer, reduz a permeabilidade do concreto com cinza de casca de arroz (CCA), o que pode antecipar a sua degradação em altas temperaturas. A literatura mostra que o concreto reidratado em água pode recuperar substancialmente a sua resistência inicial, porém, os estudos sobre a reidratação ao ar e sobre a influência do modo de resfriamento na reidratação são escassos. A pesquisa desenvolvida teve como principal objetivo avançar na análise experimental de concretos convencional e com CCA em altas temperaturas e na reidratação. Na etapa exploratória se avaliou a influência da temperatura de exposição, da adição mineral, do ambiente de acondicionamento, da taxa de aquecimento e do tempo de exposição na resistência à compressão e módulo de elasticidade. Na etapa principal se avaliou a influência do modo de resfriamento, da adição e da idade de reidratação na resistência residual. Complementarmente se utilizou o ensaio de velocidade de pulso ultrassônico (VPU) para avaliar o grau de microfissuração e correlacionar a VPU com as propriedades mecânicas residuais. Na etapa exploratória concluiu-se que a adição, a temperatura, a taxa de aquecimento e o tempo de exposição influenciaram significativamente os resultados. O concreto com CCA cristalina apresentou pior desempenho em altas temperaturas. O concreto com CCA amorfa apresentou desempenho ligeiramente inferior ao concreto convencional em 200°C, devido ao efeito da poro-pressão. No entanto, ambas as CCA podem ser alternativas viáveis considerando sustentabilidade. Na etapa principal, o resfriamento brusco com água provocou maior redução na resistência devido aos gradientes térmicos, porém, permitiu maior recuperação logo nos primeiros sete dias de reidratação. Apesar da recuperação parcial, a resistência ao fim de 154 dias foi inferior a 40% do valor inicial. Nas análises térmicas e de DRX foi possível observar nos concretos resfriados com água a recristalização dos aluminatos de cálcio, do C-S-H e da portlandita, em maior grau no concreto convencional. Foi possível observar correlações fortes entre as variáveis de resposta na etapa exploratória, porém, o mesmo não ocorreu na etapa principal, devido à fissuração e presença de água nos poros. / The pore refinement, associated with the pozzolanic reaction and the filler effect, reduces the permeability of blended concrete with rice husk ash (RHA), which can anticipate its degradation at high temperatures. The literature shows that concrete rehydrated with water can recover substantially its initial strength, but studies on rehydration in air and on the influence of the cooling method on rehydration are scarce. The main objective of this research was to evaluate the performance at high temperatures and in rehydration of conventional and blended concretes with RHA. In the exploratory stage, the influence of exposure temperature, mineral admixture, conditioning environment, heating rate and exposure time on residual strength and modulus of elasticity of heated concrete was evaluated. In the main stage, the influence of cooling method, mineral admixture and time of rehydration in an unsaturated environment on residual strength of concrete was evaluated. The ultrasonic pulse velocity test (UPV) was used to evaluate the degree of micro cracking of concrete and to correlate the UPV with residual strength and modulus. In the exploratory stage it was concluded that mineral admixture, temperature, heating rate and time of exposure significantly influenced the results. In general, concrete with partially crystalline RHA presented the worst performance at high temperatures. Concrete with amorphous RHA presented worse performance than conventional concrete only at 200°C, due to the pore-pressure effect. Despite these results, RHA can be a viable option considering sustainability and high temperatures performance. In the main stage, the rapid cooling with water caused a greater reduction in strength, due to thermal gradients, however, caused a greater strength recovery in the first seven days of rehydration. Despite this partial recovery, the final strength of both concretes after 154 days of rehydration was less than 40% of the initial value. In water-cooled concretes thermal and XRD analyzes show recrystallization of the calcium aluminates, C-S-H and portlandite, to a greater degree in conventional concrete. In the exploratory stage it was possible to observe strong correlations between the independent variables; however, the same did not occur in the main stage, due to cracking and to the presence of water in the pores.

Anfíbios anuros, de uma forma geral, são caracterizados por baixa resistência cutânea à perda de água por evaporação, altas taxas de reidratação a partir da pele e alta tolerância à desidratação. Entretanto, diferenças interespecíficas destes parâmetros do balanço hídrico podem estar associadas a características ambientais das áreas de ocorrência. No Brasil, encontramos biomas com características climáticas contrastantes e uma rica anurofauna, consistindo em um modelo interessante para o estudo da evolução do balanço hídrico em anuros. Através de uma abordagem comparativa, este estudo testou as hipóteses de que, quando comparadas às espécies de anuros que habitam ambientes mais mésicos, espécies de ambientes mais xéricos deveriam apresentar: (1) maior resistência à perda de água por evaporação, (2) maior taxa de reidratação, (3) menor sensibilidade do desempenho locomotor à desidratação e (4) maior sensibilidade do desempenho locomotor à temperaturas mais baixas e menor sensibilidade deste a temperaturas mais altas. As taxas de reidratação e a resistência da pele à perda de água por evaporação apresentaram relação alométrica respectivamente positiva e negativa com a massa corpórea, indicando a evolução de mecanismos compensatórios das modificações das relações entre área de superfície e volume corpóreo com a variação de tamanho. Anuros de ambientes caracterizados por maior restrição em disponibilidade hídrica e temperaturas mais altas apresentaram maiores taxas de reidratação, menor sensibilidade do desempenho locomotor a temperaturas mais altas e maior sensibilidade deste a temperaturas mais baixas, indicando padrões de adaptação fisiológica a características ambientais. A variação em sensibilidade do desempenho locomotor à desidratação apresentou padrões mais complexos de relação com variáveis ambientais, sendo esta relação dependente dos ambientes e grupos filogenéticos amostrados / Anuran amphibians, in general, are characterized by low skin resistance to evaporative water loss, high rates of hydration through the skin and high tolerance to dehydration. However, interspecific differences of these water balance traits can be related to environmental characteristics of the areas of occurrence. In Brazil, there are biomes with contrasting climatic conditions and rich anuran fauna, which constitute an interesting model for studies on water balance evolution in anurans. Through a comparative approach, this study tested the hypotheses that, when compared to anuran species that inhabit more mesic environments, species from xeric environments should show: (1) increased resistance to evaporative water loss, (2) higher rates of rehydration, (3) low sensitivity of locomotor performance to dehydration and (4) increased sensitivity of the locomotor performance at lower temperatures and lower sensitivity of it at higher temperatures. Rehydration rates and skin resistance to evaporative water loss showed, respectively, positive and negative allometric relations with body mass, indicating the evolution of compensatory mechanisms to changes in the relationship between surface area and volume with body size variation. Anurans from environments characterized by higher restriction in water availability and higher temperatures had higher rates of hydration, lower sensitivity of locomotor performance at higher temperatures and higher sensitivity of it at lower temperatures, indicating patterns of physiologic adaptation to environmental characteristics. The variation in sensitivity of the locomotor performance to dehydration showed more complex relation patterns with environmental variables. These relations were dependent on the environments and phylogenetic groups sampled

Les produits alimentaires secs sont courants dans l’industrie agroalimentaire. Cependant, leur innocuité n’est pas toujours assurée et de nombreux cas de toxi-infections alimentaires collectives à travers le monde sont annuellement recensés. Deux bactéries pathogènes sont particulièrement impliquées, l’une correspond à grand nombre de cas, Salmonella enterica, et l’autre est reconnue pour sa capacité à résister aux perturbations environnementales, Cronobacter spp.. Une compréhension plus poussée de l’impact du séchage et traitement thermique à l’état sec peut permettre une optimisation des procédés de de décontamination des produits alimentaires secs et contribuer à réduire le nombre de toxiinfections alimentaires. Dans un premier chapitre, une attention particulière a été portée au procédé de séchage de microorganismes pathogènes qui peut, s’il est conduit de manière rapide, réduire considérablement la cultivabilité microbienne. De cette façon, le séchage peut être considéré comme une étape supplémentaire de décontamination à condition d’en optimiser les conditions d’application. Puis dans un deuxième chapitre, l’impact de la réhydratation, rarement traitée jusqu’à présent, a été étudié afin de proposer des conditions permettant de maximiser l’inactivation bactérienne. Cette étude remet partiellement en cause les dénombrements de bactéries pathogènes dans les aliments qui peuvent être, dans quelque cas, sous estimées du fait de l’utilisation de réhydratation rapide. Dans un troisième chapitre, l’application de différents traitements thermiques sur du lait en poudre, destiné à une population dite sensible, a permis de comprendre le rôle couplé de l’activité de l’eau et de la température sur l’efficacité du traitement thermique à l’état sec mais également de proposer un modèle d’inactivation thermique des pathogènes. Il a été notamment possible de définir un paramètre représentatif de l’effet de l’activité de l’eau (yaw). Les mécanismes de mort cellulaire pour les deux bactéries ont été ensuite étudiés, que ce soit après un séchage ou après un traitement thermique. Il apparait clairement que le séchage induit majoritairement une perméabilisation de la membrane tandis que le traitement thermique des cellules viables séchées dégrade majoritairement l’activité enzymatique en détruisant peu la membrane. Finalement, il a été montré que la virulence des deux pathogènes étudiés est augmentée par le séchage mais que le traitement thermique à l’état sec n’a pas d’impact sur cette virulence. Les connaissances apportées par cette étude peuvent être utiles d’un point de vue industriel, afin d’optimiser au mieux les conditions d’application des différents procédées pour une inactivation bactérienne maximale. / Dried food products are common in food industry. Nevertheless, their safety is not well insured, involving numerous outbreaks every years around the world. Particularly, two pathogenic bacteria are of interest, one of them due to its number of cases, Salmonella enterica, and the other one due to its ability to survive environmental perturbations, Cronobacter spp.. A deeper comprehension of drying and heat treatment in dried state impact could lead to an optimization of drying and heating processes, insuring food safety. In the first instance, drying was considered as a supplementary decontamination step by optimizing its conditions of use. In a second phase, the rehydration impact was studied in order to found optimal conditions of pathogen inactivation. The study questions the rehydration currently puts in practice for food safety analysis. In a third phase, several heat treatments on a dried food product, intended to susceptible population, permitted to understand the specific role of water activity on the efficiency of heat treatment in dried state, and also propose a modelling for bacterial heat inactivation. In addition, it was possible to define two new parameters which represent the effect of temperature (zT) and the effect of water activity (yaw). Fourth, cellular death mechanisms for both studied bacteria, during the drying or during the heat treatment, were considered. It was clear that drying involved mainly membrane damages whereas heat treatment involved mainly enzymatic damages. Finally, in a fifth part, it was shown that virulence properties of both studied bacteria were affected by drying, increasing invasion capacity, but not by heat treatment in dried state. To finish, the knowledges brought by this study are useful for industrial point of view, in the case of drying and heat process optimization and also by proposing biological indicators to valid process efficiency in situ.

Résumé anglais uniquement / Nowadays there is an urgent need to develop green chemical processes, where the use and generation of toxic substances can be avoided. Indeed, the lignocellulose feedstock destructuration will produce aqueous solutions of ketones or aldehydes and it would be an important breakthrough to develop solid base catalysts capable to promote the aldol condensation. In this thesis, the main results are shown as follows: Magnesium and rare earth mixed oxides (MgReOx), rare earth modified MgAl-HT catalyst were prepared and were evaluated in liquid phase acetone self-aldolization. Rare earth modified MgAl catalysts show enhanced catalystic activity than MgReOx catalysts. Rehydrated MgAl-HT modified with Y and La, also present a higher water tolerance for aldol reaction. The same catalysts were also applied to acetone gas phase self-condensation reaction. At low temperature, the mesityl oxide is the main product for all the catalysts. At high temperatures, deactivation rate is lowered over MgAlCe(Y)O catalysts, and the presence of trimers (selectivity of IP over 50%) is much more noticeable for the MgAlY(Ce)O catalysts. A good balance between basicity and acidity is proposed to increase the selectivity of IP. In the cross condensation of citral and acetone, the citral conversion and pseudoionone yield were significantly enhanced over Mg3AlaY1-aOx catalysts. A general mechanism of reaction was proposed that the Y modified MgAl mixed oxides undergoes the rehydration by the water formed during the reaction, and the rehydrated catalysts with active Brønsted basic sites are responsible for the significantly improvement of catalytic activity

The present work had as objective to study the hydration process of grains and its possible enhancement using the ultrasound technology. For that, it was studied the hydration kinetics of different grains (Andean lupin, Adzuki beans, sorghum grains and corn kernels) correlating the morphology with mathematical models and the mass transfer mechanisms. Moreover, the effect of the soaking water temperature and the grain initial moisture content were studied to complement the description of this process. The ultrasound application was studied for improving the hydration process, describing the possible mechanisms (direct and indirect effects) that improve the mass transfer process. Therefore, it was established the way by how water enters in the studied grains, demonstrating that the water transfer into the grains is a complex phenomenon and takes place not only due to diffusional mechanisms, but also by capillarity. In addition, suitable mathematical models were proposed and used to explain the processes, describing their parameters according to the grains morphology and the mass transfer mechanisms. Further, it was determined how ultrasound enhances the mass transfer and in which conditions the direct (inertial flow and sponge effect) and the indirect effects (micro channels formation by acoustic cavitation) take place in the process, maximizing the effect of this technology. Finally, it was demonstrated that the ultrasound technology enhanced the hydration process for corn kernels, reducing significantly the process time in approximately 35 %, without modifying the thermal, structural and rheological properties of their starch. In conclusion, the present work improved the description of the grain hydration phenomenon and proved that the ultrasound technology can be used to enhance this process without changing its main industrial component. It is highlighted that the obtained results are thus high desirable for both the industrial and academic point of view. / O presente trabalho teve como objetivo estudar o processo de hidratação de grãos e sua possível melhora usando a tecnologia do ultrassom. Estudou-se a cinética de hidratação de diferentes grãos (tremoço andino, feijão Adzuki, grãos de sorgo e grãos de milho) correlacionando a morfologia com modelos matemáticos e os mecanismos de transferência de massa. Também foi estudado o efeito da temperatura e o conteúdo de umidade inicial do grão para complementar a descrição deste processo. Estudou-se a aplicação do ultrassom no processo de hidratação descrevendo-se os possíveis mecanismos (efeito diretos e indiretos) que melhoram a transferência de massa. Como resultado, foi estabelecida a forma como a água entra nos grãos estudados, demostrando que a transferência de água dentro dos grãos é um fenômeno complexo e que acontece por difusão e capilaridade. Foram propostos e utilizados modelos matemáticos apropriados para explicar os processos, descrevendo os parâmetros de acordo com a morfologia dos grãos e os mecanismos de transferência de massa. Ainda, determinou-se como o ultrassom melhora a transferência de massa e em que condições do processo acontecem os efeitos diretos (fluxo inercial e efeito esponja) e efeitos indiretos (formação de micro canais pela cavitação acústica), maximizando o efeito dessa tecnologia. Finalmente, demonstrou-se que a tecnologia do ultrassom melhora o processo de hidratação de grãos de milho, diminuindo significativamente o tempo do processo em cerca de 35 % sem alterar as propriedades térmicas, reológicas e estruturais do seu amido. Como conclusão, o presente trabalho melhorou a descrição de como os grãos são hidratados, demonstrando que o ultrassom pode ser usado para melhorar o processo de hidratação de grãos sem alterar os seus principais produtos industriais. Ressalta-se que os resultados obtidos são desejáveis tanto do ponto de vista acadêmico quanto industrial.

Ziele dieser Arbeit zum Tränkemanagement bei neonataler Kälberdiarrhoe waren, die Auswirkungen von oralen Rehydratationslösungen (ORL) auf die abomasale Milchgerinnung und den Labmagendurchmesser zu prüfen sowie die Wirksamkeit von unterschiedlich zubereiteten ORL bei bestehender Dehydratation zu vergleichen. Dazu wurden die folgenden zwei Untersuchungen durchgeführt: Die erste Untersuchung an gesunden und durchfallkranken Kälbern sollte mittels Ultraschall zeigen, ob die Einmischung eines bicarbonathaltigen Elektrolytpulvers in die Tränke deren abomasales Gerinnungsverhalten beeinträchtigt. Zeitgleich wurde der ventrodorsale Labmagendurchmesser erfasst, um daraus Rückschlüsse auf die abomasale Entleerung ziehen zu können. Diese Arbeit untersuchte erstmals die Milchgerinnung im Labmagen von spontan an Durchfall erkrankten Kälbern. In der zweiten Untersuchung sollten die Effekte der Fütterung von Milchaustauscher (MAT) sowie von in Wasser und in MAT zubereiteter ORL auf den Flüssigkeits- und Säuren-Basen-Haushalt experimentell dehydrierter Kälber ermittelt werden. Material und Methoden: Bei gesunden (n = 28) sowie durchfallkranken Kälbern (n = 15) wurde das abomasale Gerinnungsverhalten sowie der ventrodorsale Labmagendurchmesser (= Labmagenhöhe) vor und nach Fütterung von Milch bzw. MAT sowie nach Zusatz eines bicarbonathaltigen Elektrolytpulvers zur jeweiligen Tränke ultrasonografisch dargestellt. Im zweiten Untersuchungsteil wurden sechs Kälber nach einem modifizierten Protokoll von WALKER et al. (1998a) experimentell dehydriert. Im Anschluss wurden diese Tiere entweder mit MAT oder mit einer ORL, welche in Wasser (Wasser-ORL) oder MAT (MAT-ORL) zubereitet wurde, gefüttert. In einem weiteren Versuchsdurchlauf verblieben die mittel- bis hochgradig dehydrierten Probanden nüchtern. Nach einem definierten Schema wurden während der Versuchsphase venöse Blutproben vor und nach Induktion einer Dehydratation sowie vor und nach Fütterung entnommen. Es wurden Parameter des Flüssigkeits- und Säuren-Basen-Haushaltes zu den verschiedenen Untersuchungszeitpunkten bestimmt. Ergebnisse: Nach Gabe von Milch konnte mittels Ultraschall immer eine vollständige Zweiphasentrennung in Koagulum und Molke detektiert werden, wohingegen diese nach Fütterung des MAT nur unvollständig voneinander separiert waren. Die kombinierte Fütterung von Milch oder MAT und einer ORL, welche 62 bzw. 93 mmol/l Bicarbonat enthielt, führte zu keinen Unterschieden auf den ultrasonografischen Bildern des Labmageninhaltes im Vergleich zu denen der jeweiligen nativen Tränke. Des Weiteren war die abomasale Milchgerinnung nicht aufgrund eines Durchfallgeschehens gestört. Die unvollständige Gerinnung des MAT resultierte nicht in dessen schnellerer abomasaler Passage, sondern anhand des statistisch signifikant größeren Labmagendurchmessers ab vier Stunden nach MAT-Fütterung scheint es, dass die Entleerung des MAT aus dem Labmagen im Vergleich zu Milch leicht verzögert war. Innerhalb der beiden Versuchstiergruppen konnten keine statistisch signifikanten Unterschiede in Bezug auf den abomasalen Durchmesser zwischen den Tränken mit und ohne ORL-Zusatz festgestellt werden. Die statistisch signifikanten Differenzen des Labmagendurchmessers zwischen den gesunden und durchfallkranken Kälbern nach Fütterung der identischen Tränken weisen darauf hin, dass die Entleerung des Labmagens bei an Diarrhoe erkrankten Kälbern verzögert stattfindet. Bei den experimentell dehydrierten Probanden erhöhte sich das Plasmavolumen statistisch signifikant nach Aufnahme einer Tränkemahlzeit, wohingegen dieses ohne Behandlung konstant blieb. Die Rate der Plasmavolumenexpansion war nach Fütterung von MAT im Vergleich zu Wasser-ORL oder MAT-ORL vermindert. Die Zunahme des Plasmavolumens war bei den dehydrierten Kälbern nach Aufnahme von Wasser-ORL stärker ausgeprägt als nach Fütterung von MAT-ORL. Außerdem war nach Gabe der hypertonen MAT ORL die Plasmaosmolalität statistisch signifikant erhöht. Der Säuren-Basen-Status der Tiere verbesserte sich infolge der Absorption von Flüssigkeit. Dieser Effekt war allerdings weniger offensichtlich, da das Versuchsprotokoll eine hochgradige Dehydratation aber nur eine gering- bis maximal mittelgradige metabolische Azidose induzieren konnte. Schlussfolgerungen: Die unvollständige Gerinnung eines MAT im Labmagen scheint zu keiner schnelleren Entleerung zu führen. Die abomasale Milchgerinnung ist nicht beeinträchtigt, wenn die Milchfütterung mit einer 93 mmol/l Bicarbonat enthaltenden ORL kombiniert wird. Darüber hinaus resultiert aus einer Durchfallerkrankung keine Störung der Milchgerinnung im Labmagen. Die Einmischung eines bicarbonathaltigen Elektrolytpulvers in Milch oder MAT hat keine schnellere abomasale Passage der Ingesta zur Folge. Im Gegensatz zu gesunden Kälbern findet die Entleerung des Labmagens bei durchfallkranken Tieren verzögert statt. Es sind weitere Untersuchungen erforderlich, welche die Ursachen für die verlangsamte abomasale Passage bei an Durchfall leidenden Kälbern bestimmen. Aus den Ergebnissen der vorliegenden Arbeit kann geschlussfolgert werden, dass die gemeinsame Verabreichung von Milch bzw. MAT mit einem bicarbonathaltigen Elektrolytpulver weder die Milchgerinnung noch die abomasale Entleerung der Tränke bei durchfallkranken Kälbern beeinflusst. Folglich ist die Einmischung einer ORL in eine caseinhaltige Tränke möglich. Jedoch zeigen die Ergebnisse der zweiten Untersuchung, dass die Fütterung einer hypertonen MAT-ORL weniger effektiv bei der Erhöhung des Plasmavolumens dehydrierter Kälber ist als das in Wasser zubereitete Äquivalent (Wasser-ORL). Genau genommen erhöht die Verabreichung einer hypertonen MAT-ORL die Plasmaosmolalität bei dehydrierten Tieren, was möglicherweise bei durchfallkranken Kälbern zu einer akuten Kochsalzvergiftung führen könnte. In einer Folgeuntersuchung zu dieser Arbeit konnte gezeigt werden, dass die Gabe von hypertoner Milch-ORL in Kombination mit freiem Zugang zu Wasser eine effektive Behandlungsmaßnahme durchfallkranker Kälber darstellt, da die hohen Elektrolytgaben die Wasseraufnahme der Kälber stimulieren und keine Gefahr einer Hypernatriämie besteht (WENGE et al. 2014). Anhand der beiden Arbeiten kann geschlussfolgert werden, dass durchfallkranke Kälber, denen kein freier Zugang zu Wasser gewährt wird, wasserbasierte, isotone ORL erhalten sollten. / Aims of the present studies on oral rehydration management of calf diarrhoea were to reveal the effects of oral rehydration solutions (ORS) on abomasal milk clotting and abomasal diameter, as well as to compare the effectiveness of differently prepared ORS in calves with experimentally induced dehydration. For this purpose, two experiments were conducted: The first investigation in healthy and diarrhoeic calves should demonstrate via ultrasound whether the incorporation of bicarbonate-containing electrolyte powder into ‘milk meals’ impairs the abomasal coagulation of milk protein. At the same time, the ventrodorsal diameter of the abomasum was measured to outline abomasal emptying. This study is the first in which milk clotting in the abomasum of spontaneously diarrhoeic calves was investigated. The second investigation examined the effects of feeding milk replacer (MR), as well as ORS prepared in water or in MR on the fluid and acid-base balance of experimentally dehydrated calves. Materials and methods: Abomasal curd formation, as well as ventrodorsal diameter (= abomasal height), were ultrasonographically imaged in healthy (n = 28) and diarrhoeic calves (n = 15) before and after feeding milk, MR and ORS containing bicarbonate prepared in milk or MR, respectively. In the second investigation six calves were experimentally dehydrated according to a modified protocol of WALKER et al. (1998a). Subsequently, these calves were fed with either milk replacer (MR) or an ORS prepared in either water (water-ORS) or MR (MR-ORS). In one experiment, the dehydrated calves remained fasting. During the experimental period, venous blood samples were taken according to a defined schedule before and after induction of dehydration, as well as before and after feeding. Parameters of fluid and acid-base balance were determined at various timepoints. Results: After milk-feeding, a complete separation of curd and whey was always detected via ultrasound; whereas after MR-feeding, separation was incomplete. Feeding mixtures of milk or MR with ORS containing 62 - 93 mmol/L bicarbonate did not cause any differences in the ultrasonographic images of abomasal content compared to those of milk or MR. Moreover, abomasal milk clotting was not disturbed due to diarrhoea. Inadequate milk clotting of MR did not result in its faster abomasal passage but according to the significantly larger abomasal diameter starting from 4 h after MR-feeding gastric emptying of MR was slightly decreased when compared to milk. Within the two groups of experimental animals no statistically significant differences could be determined with respect to the abomasal diameter between the diets with and without addition of ORS. Statistically significant differences of abomasal diameter between healthy and diarrhoeic calves after feeding the same diet indicate that abomasal emptying is delayed in calves suffering from diarrhoea. Plasma volume increased significantly following the intake of a ‘fluid meal’ in experimentally dehydrated calves, whereas it remained constant in the absence of treatment. The rate of plasma volume expansion was reduced by feeding MR relative to water-ORS or MR-ORS. In dehydrated calves, the expansion of plasma volume was more pronounced following the intake of water-ORS compared to the feeding MR-ORS. Moreover, plasma osmolality increased significantly following the ingestion of hypertonic MR-ORS. The acid-base status of animals was corrected as a result of fluid absorption, but this effect was less obvious as the experimental protocol resulted in severe dehydration and only mild to moderate metabolic acidosis. Conclusions: Inadequate curd formation of an MR in the abomasum does not result in faster abomasal passage. Milk clotting in the abomasum is not affected when combining milk feeding with ORS containing 93 mmol/L of bicarbonate. Furthermore, abomasal curd formation is not disturbed due to diarrhoea. The addition of an bicarbonate-containing ORS in milk or MR does not result in faster abomasal passage of ingesta. In contrast to healthy calves, abomasal emptying is prolonged in diarrhoeic calves. Hence, further studies are needed to determine reasons for decelerated abomasal passage in calves suffering from diarrhoea. According to the results of the present study it can be concluded that combined feeding of milk/MR with an bicarbonate-containing ORS does not affect either milk clotting or abomasal emptying of the diet in diarrhoeic calves. Consequently, the addition of ORS to milk meal is possible. However, the results of the second investigation indicate that the feeding of hypertonic MR-ORS is less effective in increasing plasma volume of dehydrated calves than the water-based equivalent (water-ORS). In fact, administration of hypertonic MR-ORS increases plasma osmolality in dehydrated calves, potentially causing acute hypernatraemia in diarrhoeic calves. In a follow-up study to the present investigation, it could be demonstrated that feeding hypertonic milk-ORS combined with ad libitum access to water is an effective method of treating diarrhoeic calves because the high electrolyte content stimulates water intake of calves and there is no risk of hypernatraemia (WENGE et al. 2014). Based on these two studies, it can be concluded that diarrhoeic calves without free access to water should receive isotonic water-based ORS.

The thesis reports on 6 studies (2 of which were part of a multi-centre trial) examining hydration and fluid balance. The first study described in this thesis investigated the impact of hydration status on Dual energy x-ray absorptiometry (DXA) and other methods that are popular tools to determine body composition in athletes. We observed that it is important to ensure a euhydration when assessing body composition, particularly when considering changes associated with nutritional or exercise interventions. The second and third studies reported identified beverages that promote longer term fluid retention and maintenance of fluid balance in adults. We investigated the effects of 13 different commonly consumed drinks on urine output and fluid balance when ingested in a euhydrated state, with a view to establishing a beverage hydration index (BHI), i.e., the volume of urine produced after drinking expressed relative to a standard treatment (still water) for each beverage. The beverages with the highest BHI were oral rehydration solution, full fat milk and skimmed milk. BHI may be a useful measure to identify the short term hydration potential of different beverages when ingested in a euhydrated state. The fourth study aimed to systematically examine the influence of carbohydrate, sodium and caffeine content of beverages on the BHI. The BHI was greater in beverages with higher carbohydrate or higher sodium content, but not influenced by caffeine. The carbohydrate content of beverages has no effect on BHI at concentration up to 10% carbohydrate. Sodium content of beverages in concentrations of 27mmol/L and higher can improve the hydration potential of beverages. Caffeine doses in beverages up to 400mg/L do not have an impact upon diuresis when ingested in a euhydrated state. The fifth study compared net fluid balance (NFB) responses to the ingestion of commonly consumed drinks in young and older men. We observed that in young adults milk helps to maintain positive net fluid balance for longer than other drinks. In older adults this effect of milk is not observed despite similar net electrolyte balance responses. Future work should more fully explore these potential differences in fluid balance responses to drink ingestion between young and older adults. The final study investigated the hydration habits of Scottish young and older adults (+50 years old), identifying their fluid choices, volume, and preferences in relation to time of day. The results showed that 26.1% of the young females, 30.3% of the young males, 25.8% of the older females and 50.4% of the older males did not meet the European (EU) Food Safety Authority (EFSA) fluid intake recommendations. We also observed that the difference between those who met and those who did not meet the EFSA adequate intake could be attributed to differences in water ingestion, mainly during the mid-morning (after breakfast until 11 am) and during the early-afternoon (after lunch time up to 5 pm). It was concluded that these moments might be key when implementing interventions to improve hydration status especially in the older population.