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Greenhouse gas emission from a Prairie pothole landscape in Western CanadaDunmola, Adedeji Samuel 10 April 2007 (has links)
Knowing the control of landscape position in greenhouse gas (GHG) emission from the Prairie pothole region is necessary to provide reliable emission estimates needed to formulate strategies for reducing emission from the region. Presented here are results of a study investigating the control of landscape position on the flux of nitrous oxide (N2O) and methane (CH4) from an agricultural soil. Field flux of N2O and CH4 and associated soil parameters from the Upper, Middle, Lower and Riparian slope positions were monitored from spring to fall of 2005, and spring of 2006, at the Manitoba Zero-Tillage Research Association (MTRZA) farm, 17.6km North of Brandon, MB. The field site consisted of a transect of 128 chambers segmented into the four landscape positions, with either all chambers or a subset of the chambers (32) sampled on select days. Spring thaw is an important period for annual inventory of N2O emission, thus, soil samples were also collected from the four slope positions in fall 2005, and treated in the laboratory to examine how antecedent moisture and landscape position affect the freeze-thaw emission of N2O from soil.
Daily emissions of N2O and CH4 for 2005 were generally higher than for 2006, the former being a wetter year. There was high temporal variability in N2O and CH4 emission, with high fluxes associated with events like spring thaw and fertilizer application in the case of N2O, and rapid changes in soil moisture and temperature in the case of CH4. There was a high occurrence of hotspots for N2O emission at the Lower slope, associated with its high soil water-filled porosity (WFP) and carbon (C) availability. The Riparian zone was not a source of N2O emission, despite its soil WFP and organic C being comparable with the Lower slope. The hotspot for CH4 emission was located at the Riparian zone, associated with its high soil WFP and C availability. The Upper and Middle slope positions gave low emission or consumed CH4, associated with having low soil WFP and available C. This pattern in N2O and CH4 emission over the landscape was consistent with examination of entire 128 chambers on the transect or the 32 subset chambers.
Significantly lowering the antecedent moisture content of soil by drying eliminated the freeze-thaw emission of N2O, despite the addition of nitrate to the soil. This was linked to drying slightly reducing the denitrifying enzyme activity (DEA) of soil. The highest and earliest freeze-thaw emission of N2O was from the Riparian zone, associated with its high antecedent moisture content, DEA and total organic C content. The addition of nitrate to soil before freezing failed to enhance freeze-thaw emission of N2O from the Upper, Middle and Lower slope positions, but increased emission three-fold for the Riparian zone. Despite the greater potential of the Riparian zone to produce N2O at thaw compared to the Upland slopes, there was no spring-thaw emission of N2O from the zone on the field. This was because this zone did not freeze over the winter, due to insulation by high and persistent snow cover, vegetation and saturated condition. The denitrifying potential and freeze-thaw N2O emission increased in going from the Upper to the Lower slope position, similar to the pattern of N2O emission observed on the field.
The localization of hotspots for N2O and CH4 emission within the landscape was therefore found to be driven by soil moisture and C availability. When estimating GHG emission from soil, higher emission index for N2O and CH4 should be given to poorly-drained cropped and vegetated areas of the landscape, respectively. The high potential of the Riparian zone for spring-thaw emission of N2O should not be discountenanced when conducting annual inventory of N2O emission at the landscape scale. When fall soil moisture is high, snow cover is low, and winter temperature is very cold, freeze-thaw emission of N2O at the Riparian zones of the Prairie pothole region may be very high.
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Degradation of a Polymer Electrolyte Membrane Fuel Cell Under Freeze Start-up OperationRea, Christopher January 2011 (has links)
The polymer electrolyte membrane fuel cell (PEMFC) is an electrochemical device used for the production of power, which is a key for the transition towards green and renewable power delivery devices for mobile, stationary and back-up power applications. PEMFCs consume hydrogen and oxygen to produce power, water and heat. The transient start-up from sub-zero freezing temperature conditions is a problem for the successful, undamaged and unhindered operation. The generation and presence of water in the PEMFC stack in such an environment leads to the formation of ice that hinders the flow of gases, causes morphological changes in the membrane electrode assembly (MEA) leading to reversible and irreversible degradation of stack performance.
Start-up performance is highly dependent on start-up operational conditions and procedures. The previous state of the stack will influence the ability to perform upon the next start-up and operation. Water generated during normal operation is vital and improves performance when properly managed. Liquid water present at shut-down can form ice and cause unwanted start-up effects. This phase change may cause damage to the MEA and gas diffusion media due to volume expansion. Removal of high water content at shutdown decreases proton conductivity which can delay start-up times. The United States Department of Energy (DOE) has established a set of criteria that will make fuel cell technology viable when attained. As specified by DOE, an 80 kWe fuel cell will be required by 2015 to reach 50% power in 30 seconds from start-up at an ambient temperature of -20°C.
This work investigates freeze start-up in a multi-kilowatt stack approaching both shut-down conditioning and start-up operations to improve performance, moderate fuel cell damage and determine the limits of current stack technology. The investigation involved a Hydrogenics Corporation 5 kW 506 series fuel cell stack. The investigation is completed through conditioning the fuel cell start-up performance at various temperatures ranging from -5°C to below -20°C. The control of system start-up temperature is achieved with an environmental chamber that maintains the desired set point during dwell time and start-up. The supply gases for the experiment are conditioned at ambient stack temperature to create a realistic environment that could be experienced in colder weather climates. Temperature controls aim to maintain steady ambient temperatures during progressive start-up in order to best simulate ambient conditions. The control and operation of the fuel cell is maintained by the use of a fuel cell automated test station (FCATS™). FCATS supplies gas feeds, coolant medium and can control temperature and reactant humidity in reactants according to a prescribed procedure for continuous operation. The
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collection of data occurs by the same system recording cell voltage, temperatures, pressures, flow rates and current densities. A procedural start-up and characterization are conducted in order improve start-of performance and examine reactant flows, coolant activation time, stack conditioning and the effects by freezing temperatures. The resulting degradation is investigated by polarization curves and various ex-situ measurements. In this work, it was found that freeze start-up of a fuel cell stack can be aided and managed by conditioning the stack at shut-down and applying a procedure to successfully start-up and mitigate the damage that freezing can cause.
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Evaluation of the Performance of Pervious Concrete Pavement in the Canadian ClimateHenderson, Vimy Ina January 2012 (has links)
Pervious concrete pavement has the capacity to perform as two types of infrastructure: a pavement; and a stormwater management solution. It is a low impact development as it does not alter the natural hydrological cycle when implemented, unlike a conventional impermeable pavement. This research represents some of the initial investigations into pervious concrete pavement in Canada. The two research hypotheses of this research were the following:
1. Pervious concrete pavement can be successfully planned, designed, constructed and maintained in Canada for successful performance based on surface evaluations of permeability rate and surface condition.
2. Verification that the subsurface drainage capabilities of pervious concrete pavement are as described in literature and can be quantified using instrumentation.
Through monitoring of the design, construction, performance and maintenance of five field sites across Canada and various laboratory pavement slabs, the behaviour of pervious concrete pavement in freeze-thaw conditions has been evaluated. This thesis presents the findings from the various phases of the life cycle of pervious concrete pavement: planning; design; construction; and maintenance. An interpretation of the performance of pervious concrete pavement both from the perspective of the surface and subsurface is included.
The various field sites led to pervious concrete being used in areas exposed to static or parked traffic and areas with slow moving traffic. At the two sites that included static and slow moving traffic, the permeability performance was better in the areas of static traffic than those with moving traffic. Each of the field sites had a unique mix design and some had multiple variations of one basic mix design. The relationship between the void content and hardened density of the pervious concrete cores was linear with none of the cores being visually identified as outliers.
Substantial deterioration in pavement structure performance was identified at one site. Other field sites showed changes in structural capacity over the monitoring timeline. However, no locations of substantial decreases in structural capacity were identified.
The surface condition of the sites over the analysis period indicated that compaction to the surface during construction was helpful in constructing a quality pavement. The results of the project indicated that pervious concrete will crack when joints are not included and may also crack similarly to conventional impermeable concrete pavements if joints are spaced too widely or do not match joints of adjacent pavement.
Washing the pervious concrete pavement surface with a large hose or garden hose was found to be the most effective in improving permeability across a site and also in increasing the permeability of the pervious concrete. The initial permeability of the pervious concrete pavement was found to influence future performance.
Freeze-thaw cycling and moisture were found to alter the internal structure of pervious concrete. However, did not generally lead to surface distress development. The application of sand as a winter maintenance method decreased the permeability, as did the use of a salt solution. However, neither winter maintenance method led to the permeability rates of laboratory slabs dropping below an acceptable level. All three slabs loaded with a salt solution deteriorated to a point where the slabs had failed. The initial permeability of the field sites proved to be important and although some sites started with what appeared to be very high permeability rates, these sites were successful in the multiple year evaluation in maintaining adequate permeability rates. The types of surface distresses that developed in the cores and slabs in the laboratory were generally not substantially worse at the field sites, suggesting that pedestrian and vehicle traffic do not necessarily escalate distresses caused by the Canadian climate and corresponding winter activities.
The subsurface drainage that was quantified by the instrumentation included in three field sites confirmed observations from the surface of the pavement and exceeded other expectations. Two field sites exhibited limited drainage capabilities on the surface of the pervious concrete pavement, one shortly after construction, and the other within a year following construction. The subsurface analysis quantified and confirmed that moisture was not able to drain completely vertically through the pavement structures at these two sites due to the limited access in the pervious concrete pavement surface. In comparison, the subsurface drainage at another site surpassed the assumed behaviour of pervious concrete pavement structures. The pavement structure in general at this site was highly permeable and this was identified as moisture was not observed to be collecting in the bottom of the storage base layer at any time or for any period of time. The successful overall drainage performance of this site demonstrates the ability to effectively use pervious concrete pavement in Canada.
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Greenhouse gas emission from a Prairie pothole landscape in Western CanadaDunmola, Adedeji Samuel 10 April 2007 (has links)
Knowing the control of landscape position in greenhouse gas (GHG) emission from the Prairie pothole region is necessary to provide reliable emission estimates needed to formulate strategies for reducing emission from the region. Presented here are results of a study investigating the control of landscape position on the flux of nitrous oxide (N2O) and methane (CH4) from an agricultural soil. Field flux of N2O and CH4 and associated soil parameters from the Upper, Middle, Lower and Riparian slope positions were monitored from spring to fall of 2005, and spring of 2006, at the Manitoba Zero-Tillage Research Association (MTRZA) farm, 17.6km North of Brandon, MB. The field site consisted of a transect of 128 chambers segmented into the four landscape positions, with either all chambers or a subset of the chambers (32) sampled on select days. Spring thaw is an important period for annual inventory of N2O emission, thus, soil samples were also collected from the four slope positions in fall 2005, and treated in the laboratory to examine how antecedent moisture and landscape position affect the freeze-thaw emission of N2O from soil.
Daily emissions of N2O and CH4 for 2005 were generally higher than for 2006, the former being a wetter year. There was high temporal variability in N2O and CH4 emission, with high fluxes associated with events like spring thaw and fertilizer application in the case of N2O, and rapid changes in soil moisture and temperature in the case of CH4. There was a high occurrence of hotspots for N2O emission at the Lower slope, associated with its high soil water-filled porosity (WFP) and carbon (C) availability. The Riparian zone was not a source of N2O emission, despite its soil WFP and organic C being comparable with the Lower slope. The hotspot for CH4 emission was located at the Riparian zone, associated with its high soil WFP and C availability. The Upper and Middle slope positions gave low emission or consumed CH4, associated with having low soil WFP and available C. This pattern in N2O and CH4 emission over the landscape was consistent with examination of entire 128 chambers on the transect or the 32 subset chambers.
Significantly lowering the antecedent moisture content of soil by drying eliminated the freeze-thaw emission of N2O, despite the addition of nitrate to the soil. This was linked to drying slightly reducing the denitrifying enzyme activity (DEA) of soil. The highest and earliest freeze-thaw emission of N2O was from the Riparian zone, associated with its high antecedent moisture content, DEA and total organic C content. The addition of nitrate to soil before freezing failed to enhance freeze-thaw emission of N2O from the Upper, Middle and Lower slope positions, but increased emission three-fold for the Riparian zone. Despite the greater potential of the Riparian zone to produce N2O at thaw compared to the Upland slopes, there was no spring-thaw emission of N2O from the zone on the field. This was because this zone did not freeze over the winter, due to insulation by high and persistent snow cover, vegetation and saturated condition. The denitrifying potential and freeze-thaw N2O emission increased in going from the Upper to the Lower slope position, similar to the pattern of N2O emission observed on the field.
The localization of hotspots for N2O and CH4 emission within the landscape was therefore found to be driven by soil moisture and C availability. When estimating GHG emission from soil, higher emission index for N2O and CH4 should be given to poorly-drained cropped and vegetated areas of the landscape, respectively. The high potential of the Riparian zone for spring-thaw emission of N2O should not be discountenanced when conducting annual inventory of N2O emission at the landscape scale. When fall soil moisture is high, snow cover is low, and winter temperature is very cold, freeze-thaw emission of N2O at the Riparian zones of the Prairie pothole region may be very high.
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Studies on the stabilization of lyophilized lipid/DNA complexes during storage /Molina Salinas, Marion Del Carmen. January 2007 (has links)
Thesis (Ph.D. in Pharmaceutical Sciences) -- University of Colorado Denver, 2007. / Typescript. Includes bibliographical references (leaves 136-153).
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Fabrication of PHBV and PHBV-based composite tissue engineering scaffolds through the emulsion freezing/freeze-drying process and evaluation of the scaffolds /Sultana, Naznin. January 2009 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (p. 253-274). Also available online.
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Protection Mechanisms of Excipients on Lactate Dehydrogenase during Freeze-Thawing and LyophilizationMi, Yanli. January 2002 (has links)
Thesis (Ph. D.)--University of Tennessee, Memphis, 2002.
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Preservation of two therapeutic biopharmaceuticals using sugars and polymers : hematopoietic stem and progenitor cells and a live attenuated viral vaccine /Buchanan, Sandhya S. January 2006 (has links)
Thesis (Ph.D. in Pharmaceutical Sciences) -- University of Colorado, 2006. / Typescript. Includes bibliographical references (leaves 191-216). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;
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Caracterização e estabilidade de micropartículas de antocianinas extraídas do bagaço da produção do suco de jabuticabaSouza, Ana Cardinale Pereira January 2014 (has links)
A busca de fontes alternativas de pigmentos naturais tem estimulado o desenvolvimento de pesquisas com diferentes frutos e resíduos tropicais. No presente trabalho, optou-se por estudar o aproveitamento do bagaço gerado na produção de suco de jabuticaba. A jabuticaba é uma fruta rica em antocianinas, um pigmento natural que, além da capacidade de conferir cor, também possui atividades benéficas à saúde. No entanto, o seu uso como corante natural na indústria de alimentos como uma forma de substituir os corantes sintéticos é limitado pela sua instabilidade frente às condições de processamento e da presença de outros componentes. Uma alternativa para aumentar a estabilidade das antocianinas é através da técnica de microencapsulação no qual o ingrediente sensível é protegido dentro do material de revestimento. Assim, o presente estudo objetivou a produção, caracterização e a verificação da estabilidade dos pós obtidos por liofilização utilizando a maltodextrina, a pectina e a proteína isolada de soja como materiais de parede em diferentes proporções. Os pós foram caracterizados quanto ao teor de umidade, atividade de água, solubilidade, higroscopicidade, tamanho de partícula, morfologia, análise térmica e colorimétrica, teor de fenólicos totais, antocianinas monoméricas e atividade antioxidante com o radical ABTS. Os mesmos também foram avaliados quanto à estabilidade na presença da luz UV durante a estocagem e comparadas com o extrato de antocianinas liofilizado não microencapsulado. As antocianinas presentes no bagaço de jabuticaba foram extraídas com ultrassom utilizando a água acidificada com ácido cítrico (1 %) O extrato de antocianinas concentrado apresentou uma quantidade de antocianinas monoméricas de 510 ± 0,09 mg.100 g-1 de bagaço, um teor de fenólicos totais de 12.860 ± 1,5 mg AGE.100 g-1 bagaço e uma atividade antioxidante de 39.590 ± 1,25 μM TE.g-1 de bagaço todos expressos em base seca. Os pós produzidos por liofilização apresentaram estruturas irregulares amorfas sem estrutura cristalina com tamanho médio de partículas entre 311,66 – 419,74 μm com distribuição bimodal. Além disso, as amostras apresentaram baixos valores de umidade (2,09 ± 0,10 a 4,15 ± 0,32%), atividade de água (0,053 ± 0,003 a 0,162 ± 0,002), higroscopicidade (10,8 ± 0,1 a 14,2 ± 0,3 g/100g) e baixa solubilidade em água (10,9 ± 0,1 a 21,3 ± 0,2 %), atributos desejáveis na obtenção de alimentos em pó. Com a análise térmica foi possível verificar que houve a microencapsulação das antocianinas com os diferentes materiais de revestimento testados devido à formação de novas transições endotérmicas, e ainda foi possível observar que os pós apresentaram uma estabilidade térmica até a temperatura de 130 °C. A fotoestabilidade dos pós liofilizados bem como do extrato de antocianinas liofilizado não microencapsulado armazenados por 90 dias mostraram que a degradação desse pigmento seguiu uma cinética de primeira ordem e os parâmetros cinéticos foram calculados Para o extrato não microencapsulado os valores obtidos para a constante de degradação e tempo de meia-vida foram iguais a 0,0135 d-1 e 51 dias, respectivamente, correspondendo a uma redução de 77% de antocianinas monoméricas, 56 % de fenólicos totais e 43 % da capacidade antioxidante. Por outro lado, os materiais de parede protegeram o pigmento do efeito deletério da luz em mais de 90 % em relação ao teor de fenólicos totais, 80 % para a quantidade de antocianinas monoméricas, de modo que a atividade antioxidante foi mantida em 70 % durante o período de estocagem. Os valores da constante de degradação para todas as formulações variaram de 0,0022 a 0,0070 d-1 e os tempos de meia-vida variaram de 101 a 320 dias. Portanto, os resultados obtidos neste estudo demonstraram que a pectina e a proteína isolada de soja podem ser consideradas potenciais materiais de revestimento na microencapsulação de antocianinas a serem utilizados na indústria de alimentos. / The search for alternative sources of natural pigments has stimulated the development of research with different tropical fruits and their waste; in the present work, we chose to study the use of the bagasse generated in the production of jaboticaba juice was studied. Jaboticaba is a fruit rich in anthocyanins, a natural pigment, which besides the ability of providing color, also has beneficial health activities. However, its use as a natural colorant in the food industry, replacing the synthetic coloring agents is limited by their instability due to the process conditions and the presence of other components. An alternative to increase stability of anthocyanins is microencapsulation technique in which the sensitive ingredient is protected within the coating material. The present work aims the production, characterization and verification of the stability of the powders obtained by freeze-drying using maltodextrin, pectin and the isolate soy protein as wall materials in different proportions. The powders were analyzed for moisture content, water activity, solubility, hygroscopicity, particle size, morphology, thermal and colorimetric analysis, total phenolics content, total monomeric anthocyanin and capacity to scavenge the ABTS.+. They were also evaluated for stability in the presence of UV light during storage and compared with the lyophilized extract of anthocyanins not microencapsulated. Anthocyanins were extracted from jaboticaba pomace with ultrasound using water acidified with citric acid (1%) The concentrated extract anthocyanins showed an amount of monomeric anthocyanins of 510 ± 0.09 mg. 100g-1 a content of total phenolics of 12.860 ± 1.5 mg GAE.100g-1 and antioxidant activity of 39,590 ± 1.25 μM TE.g-1 pomace dry basis. In addition, the samples presented low moisture values (2.09 ± 0.10 to 4.15 ± 0.32%), low water activity (0.053 ± 0.003 to 0.162 ± 0.002) and hygroscopicity ranging from 10.8 ± 0.1 to 14.2 ± 0.3 g/100g as well as low solubility in water (10.86 ± 0.1 to 21.28 ± 0.2%) which are desirable attributes for food powder. Through the thermal analysis it was verified that the anthocyanins were effectively microencapsulated with the different coating materials tested due to the formation of new endothermic transitions; it was also observed that the powders showed a thermal stability up to 130 °C. The photostability the powders and extract of anthocyanins lyophilized not microencapsulated stored for 90 days showed that this pigment degradation followed a first-order kinetics. For the extract not microencapsulated the values obtained of degradation and half-life were equal to 0.0135 d-1 and 51 days, respectively, corresponding to a 77 % reduction of monomeric anthocyanins, 56% total phenolics content and 43 % of antioxidant capacity In contrast, the wall material protected the pigment against the deleterious effect of light in more than 90 % for total phenolic content and 80 % for the amount of monomeric anthocyanins, so the antioxidant activity remained at 70 % for the storage period. The rate constants according to a first-order reaction for all formulations ranged from 0.0022 to 0.0070 d-1 and the half-life times ranged from 101 to 320 days. Therefore, the results of this study showed that the pectin and the isolate soy protein can be potentially be used as coating materials in the microencapsulation of anthocyanins for use in the food industry.
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Uso do amido de pinhão como agente encapsulanteSpada, Jordana Corralo January 2011 (has links)
B-caroteno corresponde a um pigmento natural que além de possuir amplo poder corante, possui atividade antioxidante e pró-vitamínica, porém devido ao seu alto grau de insaturações, esse carotenóide é propenso à isomerização e oxidação durante o processamento e a estocagem, dificultando sua utilização na indústria de alimentos. A microencapsulação pode amenizar essa situação, aumentando sua estabilidade e tornando possível sua incorporação em sistemas alimentícios sem a perda de suas propriedades funcionais. O presente trabalho objetivou a produção, caracterização e a verificação da estabilidade das cápsulas formadas por liofilização utilizando um novo material de parede, o amido de pinhão. Amido nativo, amido hidrolisado com dextrose equivalente (DE) 6, amido hidrolisado DE 12 e a mistura destes com a gelatina foram utilizados como agentes encapsulantes. Os primeiros testes realizados foram em relação à modificação do amido via hidrólise ácida através de um planejamento fatorial 22, onde as variáveis independentes corresponderam à temperatura (30 a 44°C) e à concentração de ácido (3 a 5 mol.L-1) e a variável de resposta correspondeu à dextrose equivalente (DE). Neste estudo, verificou-se que sob maiores valores de temperatura e concentração de ácido, maiores valores de DE foram encontrados. As cápsulas foram caracterizadas quanto à sua eficiência, conteúdo superficial, morfologia, umidade, solubilidade, tamanho de partícula, temperatura de transição vítrea e isotermas de sorção. As mesmas também foram avaliadas quanto à estabilidade, em relação ao -caroteno livre, em diferentes condições: exposição à luz UV, e a 10 e 30°C. As diferentes formulações do material encapsulante resultaram em diferentes retenções de -caroteno, sendo que a formulação com amido DE 12 apresentou a melhor eficiência e a menor foi apresentada pela formulação com amido nativo. As partículas produzidas por liofilização mostraram formas indefinidas e tamanhos variados, típicos do método de encapsulação empregado. Através da análise do tamanho de partícula, verificou-se que as formulações com gelatina apresentaram um diâmetro de partícula médio superior às outras amostras. O amido nativo e hidrolisado apresentaram temperaturas de transição vítrea (Tg) similares resultando em microencapsulados com Tg também similares, porém maiores valores foram obtidos quando a gelatina foi incorporada às formulações. Todas as amostras apresentaram baixa solubilidade em água fria, e uma maior solubilidade em água quente. As isotermas de sorção dos encapsulados preparados com amido DE 12, nas temperaturas de 10°, 20° e 30°C apresentaram isoterma sigmoidal do tipo II. Quanto aos testes de estabilidade, a cinética de degradação do B-caroteno livre e encapsulado seguiu o modelo cinético de primeira ordem em todas as condições analisadas. O amido hidrolisado DE 12 foi considerado o melhor material de parede testado, visto que diminuiu de forma considerável a velocidade de degradação (k), até mesmo na presença da luz UV, onde o -caroteno foi menos estável. Os resultados encontrados neste estudo demonstraram que o amido de pinhão hidrolisado pode ser considerado um potencial agente encapsulante a ser utilizado na indústria de alimentos. / The B-carotene represents a natural pigment that besides having broad coloring power, also presents antioxidant and provitamin activity. However, due to the high degree of insaturations, this dye is propense to isomeration and oxidation during the processing and storage, being difficult its use in food industry. Microencapsulation can improve this situation, increasing its stability and rendering possible its incorporation into food systems without loss of its functional properties. The purpose of this research was to produce, characterize and investigate the stability of the microcapsules produced by freeze drying, using a new wall material corresponding to pinhão starch. The-caroteno was microencapsulated using native pinhão starch, hydrolyzed pinhão starch DE 6, hydrolyzed pinhão starch DE 12 and the mixture of both with gelatin, as coating material. First tests were related to the modification of starch via acid hydrolysis using a 22 factorial central design, where the independent variables were temperature (from 30 to 44°C) and acid concentration (from 3 to 5 mol.L-1) and the response variable corresponded to dextrose equivalent (DE). In this study, it was observed that higher temperatures and acid concentration, resulted in higher DE values. The capsules efficiency, surface content, moisture, morphology, solubility, particle size, glass transition temperature and sorption isotherms were analyzed. Also the stability of the microencapsulates were evaluated and compared to synthetic free -carotene at the storage condition: exposure to UV light, and temperatures of 10 and 30 °C. Different coating material formulations resulted in differents B-carotene retention, the formulation with hydrolyzed starch 12 DE presented the highest total content of B-carotene (>90 %) and the lowest surface B-carotene while the lowest total content of B-carotene and the highest surface of this compound was presented using native starch. All capsules showed undefined shapes and varied sizes and these characteristics are related to the process used for the preparation of microcapsules. By the particle size distribution analysis, it was verified that encapsulates with gelatin presented an average particle diameter higher than the others encapsulated. Both capsules prepared with native starch and hydrolyzed starch presented similar glass transition temperature, while capsules with gelatin showed higher Tg values (~90°C). All samples presented low cold water solubility and the hot water solubility for all samples was higher than the cold water solubility. The moisture sorption isotherms determined at 10°, 20° and 30°C of hydrolyzed starch DE 12 showed isotherms kind II. The kinetic of degradation of -carotene in encapsulates followed the first-order model. UV light, the microcapsules were less stable than the in the other conditions. The results indicated that the hydrolyzed pinhão starch is a potential encapsulating material.
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