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Gum arabic and constituent sugars studied by electron spin resonanceMasmas, Ahmad Ben Ahmad Salem January 1991 (has links)
No description available.
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Desenvolvimento e aplicação de filmes biodegradáveis com antioxidantes extraídos a partir de bagaço de uva, um resíduo da indústria vitivinícolaStoll, Liana January 2015 (has links)
O consumo abusivo de embalagens plásticas tem causado diversos problemas ambientais, visto que as mesmas são produzidas a partir de fontes não renováveis de energia e são resistentes à degradação. Neste contexto, o desenvolvimento de filmes biodegradáveis ativos para aplicação em alimentos é de grande importância pois, além de serem produzidos a partir fontes renováveis e mais sustentáveis, os mesmos podem interagir com o produto embalado e proporcionar benefícios extras em relação aos filmes convencionais. Este trabalho utilizou o bagaço de uva proveniente do processo de vinificação como fonte de antocianinas para o desenvolvimento de filmes biodegradáveis com propriedades antioxidantes. A microencapsulação das antocianinas, realizada com a finalidade de aumentar sua estabilidade, utilizou maltodextrina e goma arábica como agentes encapsulantes. Diferentes formulações de filmes biodegradáveis foram desenvolvidas com as microcápsulas produzidas. Goma arábica, maltodextrina e a combinação das mesmas foram eficientes no processo de microencapsulação (>90% de retenção de antocianinas). Apesar de apresentarem o mesmo teor de antocianinas - quantificadas via cromatografia líquida de alta eficiência - a atividade antioxidante das microcápsulas de goma arábica foi maior. A diferença entre a atividade antioxidante das cápsulas foi atribuída às diferentes solubilidades destas em água, onde maiores solubilidades poderiam liberar mais facilmente as antocianinas encapsuladas. O filme desenvolvido a partir de antocianinas encapsuladas com maltodextrina apresentou melhores propriedades mecânicas e ofereceu maior proteção ao óleo de girassol frente às reações de oxidação, e portanto foi utilizado na produção de sachês de azeite de oliva extra-virgem. O filme desenvolvido apresentou biodegradabilidade comprovada e propiciou maior estabilidade oxidativa ao azeite de oliva nele embalado quando comparado a um azeite embalado em polipropileno comercial. Os resultados obtidos neste trabalho comprovam a potencialidade da utilização de maltodextrina como encapsulante de antocianinas e como ingrediente na produção de filmes biodegradáveis, aplicados principalmente em produtos gordurosos. / The abuse of plastic packaging has caused various environmental problems, since they are produced from non-renewable sources of energy and are resistant to degradation. In this context, the development of active biodegradable films for application in foods is of great importance, since they are produced from renewable and sustainable sources, besides they may interact with the packaged product and provide additional benefits over conventional films. This study used the wine grape pomace as a source of anthocyanins for the development of biodegradable films with antioxidant properties. Microencapsulation of anthocyanins, which was carried out with the purpose of increasing its stability, used maltodextrin and gum arabic as wall materials. Different formulations of biodegradable films were developed with the obtained microcapsules. Gum arabic, maltodextrin and their combination were effective in the microencapsulation process (> 90% retention of anthocyanins). Despite being provided with the same anthocyanins content - quantified by highperformance liquid chromatography - the antioxidant activity of gum arabic microcapsules was greater. The difference between the antioxidant activity of the capsules was attributed to their different solubility in water, so that capsules with higher solubility could release more easily the encapsulated anthocyanins. The film containing anthocyanins encapsulated with maltodextrin showed better mechanical properties and offered greater protection to sunflower oil against oxidation reactions, and so was used in the production of extra-virgin olive oil pouches. The developed film, which was proven to be biodegradable, increased the oxidative stability of the olive oil when compared to olive oil packaged in a commercial polypropylene. The results of this study demonstrate the potential usage of maltodextrin as wall material on encapsulation of anthocyanins and as an ingredient in the production of biodegradable films, mainly applied in fatty products.
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Desenvolvimento e aplicação de filmes biodegradáveis com antioxidantes extraídos a partir de bagaço de uva, um resíduo da indústria vitivinícolaStoll, Liana January 2015 (has links)
O consumo abusivo de embalagens plásticas tem causado diversos problemas ambientais, visto que as mesmas são produzidas a partir de fontes não renováveis de energia e são resistentes à degradação. Neste contexto, o desenvolvimento de filmes biodegradáveis ativos para aplicação em alimentos é de grande importância pois, além de serem produzidos a partir fontes renováveis e mais sustentáveis, os mesmos podem interagir com o produto embalado e proporcionar benefícios extras em relação aos filmes convencionais. Este trabalho utilizou o bagaço de uva proveniente do processo de vinificação como fonte de antocianinas para o desenvolvimento de filmes biodegradáveis com propriedades antioxidantes. A microencapsulação das antocianinas, realizada com a finalidade de aumentar sua estabilidade, utilizou maltodextrina e goma arábica como agentes encapsulantes. Diferentes formulações de filmes biodegradáveis foram desenvolvidas com as microcápsulas produzidas. Goma arábica, maltodextrina e a combinação das mesmas foram eficientes no processo de microencapsulação (>90% de retenção de antocianinas). Apesar de apresentarem o mesmo teor de antocianinas - quantificadas via cromatografia líquida de alta eficiência - a atividade antioxidante das microcápsulas de goma arábica foi maior. A diferença entre a atividade antioxidante das cápsulas foi atribuída às diferentes solubilidades destas em água, onde maiores solubilidades poderiam liberar mais facilmente as antocianinas encapsuladas. O filme desenvolvido a partir de antocianinas encapsuladas com maltodextrina apresentou melhores propriedades mecânicas e ofereceu maior proteção ao óleo de girassol frente às reações de oxidação, e portanto foi utilizado na produção de sachês de azeite de oliva extra-virgem. O filme desenvolvido apresentou biodegradabilidade comprovada e propiciou maior estabilidade oxidativa ao azeite de oliva nele embalado quando comparado a um azeite embalado em polipropileno comercial. Os resultados obtidos neste trabalho comprovam a potencialidade da utilização de maltodextrina como encapsulante de antocianinas e como ingrediente na produção de filmes biodegradáveis, aplicados principalmente em produtos gordurosos. / The abuse of plastic packaging has caused various environmental problems, since they are produced from non-renewable sources of energy and are resistant to degradation. In this context, the development of active biodegradable films for application in foods is of great importance, since they are produced from renewable and sustainable sources, besides they may interact with the packaged product and provide additional benefits over conventional films. This study used the wine grape pomace as a source of anthocyanins for the development of biodegradable films with antioxidant properties. Microencapsulation of anthocyanins, which was carried out with the purpose of increasing its stability, used maltodextrin and gum arabic as wall materials. Different formulations of biodegradable films were developed with the obtained microcapsules. Gum arabic, maltodextrin and their combination were effective in the microencapsulation process (> 90% retention of anthocyanins). Despite being provided with the same anthocyanins content - quantified by highperformance liquid chromatography - the antioxidant activity of gum arabic microcapsules was greater. The difference between the antioxidant activity of the capsules was attributed to their different solubility in water, so that capsules with higher solubility could release more easily the encapsulated anthocyanins. The film containing anthocyanins encapsulated with maltodextrin showed better mechanical properties and offered greater protection to sunflower oil against oxidation reactions, and so was used in the production of extra-virgin olive oil pouches. The developed film, which was proven to be biodegradable, increased the oxidative stability of the olive oil when compared to olive oil packaged in a commercial polypropylene. The results of this study demonstrate the potential usage of maltodextrin as wall material on encapsulation of anthocyanins and as an ingredient in the production of biodegradable films, mainly applied in fatty products.
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Desenvolvimento e aplicação de filmes biodegradáveis com antioxidantes extraídos a partir de bagaço de uva, um resíduo da indústria vitivinícolaStoll, Liana January 2015 (has links)
O consumo abusivo de embalagens plásticas tem causado diversos problemas ambientais, visto que as mesmas são produzidas a partir de fontes não renováveis de energia e são resistentes à degradação. Neste contexto, o desenvolvimento de filmes biodegradáveis ativos para aplicação em alimentos é de grande importância pois, além de serem produzidos a partir fontes renováveis e mais sustentáveis, os mesmos podem interagir com o produto embalado e proporcionar benefícios extras em relação aos filmes convencionais. Este trabalho utilizou o bagaço de uva proveniente do processo de vinificação como fonte de antocianinas para o desenvolvimento de filmes biodegradáveis com propriedades antioxidantes. A microencapsulação das antocianinas, realizada com a finalidade de aumentar sua estabilidade, utilizou maltodextrina e goma arábica como agentes encapsulantes. Diferentes formulações de filmes biodegradáveis foram desenvolvidas com as microcápsulas produzidas. Goma arábica, maltodextrina e a combinação das mesmas foram eficientes no processo de microencapsulação (>90% de retenção de antocianinas). Apesar de apresentarem o mesmo teor de antocianinas - quantificadas via cromatografia líquida de alta eficiência - a atividade antioxidante das microcápsulas de goma arábica foi maior. A diferença entre a atividade antioxidante das cápsulas foi atribuída às diferentes solubilidades destas em água, onde maiores solubilidades poderiam liberar mais facilmente as antocianinas encapsuladas. O filme desenvolvido a partir de antocianinas encapsuladas com maltodextrina apresentou melhores propriedades mecânicas e ofereceu maior proteção ao óleo de girassol frente às reações de oxidação, e portanto foi utilizado na produção de sachês de azeite de oliva extra-virgem. O filme desenvolvido apresentou biodegradabilidade comprovada e propiciou maior estabilidade oxidativa ao azeite de oliva nele embalado quando comparado a um azeite embalado em polipropileno comercial. Os resultados obtidos neste trabalho comprovam a potencialidade da utilização de maltodextrina como encapsulante de antocianinas e como ingrediente na produção de filmes biodegradáveis, aplicados principalmente em produtos gordurosos. / The abuse of plastic packaging has caused various environmental problems, since they are produced from non-renewable sources of energy and are resistant to degradation. In this context, the development of active biodegradable films for application in foods is of great importance, since they are produced from renewable and sustainable sources, besides they may interact with the packaged product and provide additional benefits over conventional films. This study used the wine grape pomace as a source of anthocyanins for the development of biodegradable films with antioxidant properties. Microencapsulation of anthocyanins, which was carried out with the purpose of increasing its stability, used maltodextrin and gum arabic as wall materials. Different formulations of biodegradable films were developed with the obtained microcapsules. Gum arabic, maltodextrin and their combination were effective in the microencapsulation process (> 90% retention of anthocyanins). Despite being provided with the same anthocyanins content - quantified by highperformance liquid chromatography - the antioxidant activity of gum arabic microcapsules was greater. The difference between the antioxidant activity of the capsules was attributed to their different solubility in water, so that capsules with higher solubility could release more easily the encapsulated anthocyanins. The film containing anthocyanins encapsulated with maltodextrin showed better mechanical properties and offered greater protection to sunflower oil against oxidation reactions, and so was used in the production of extra-virgin olive oil pouches. The developed film, which was proven to be biodegradable, increased the oxidative stability of the olive oil when compared to olive oil packaged in a commercial polypropylene. The results of this study demonstrate the potential usage of maltodextrin as wall material on encapsulation of anthocyanins and as an ingredient in the production of biodegradable films, mainly applied in fatty products.
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Avalia??o de propriedades qu?micas e f?sicas da goma de cajueiro processada por extrus?o termopl?stica / Cashew gum (Anacardium occidentale): evaluation of physical and chemical modifications by extrusionANDRADE, Kelita Carlos Silva 04 May 2012 (has links)
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Previous issue date: 2012-05-04 / Tropical countries such, as Brazil, are the custodians of a great variety of sources of plant polysaccharides known and others not yet explored that have great potential in industrial applications among which we mention the cashew gum. Due to structural similarity between cashew gum and gum Arabic, some studies report the possibility of replacement of them. Thus, this study aims to increase the technical and scientific knowledge on the technological properties of cashew gum and compare it with gum arabic in order to ensure its application in the food industry. Hence, in this study the cashew gum and arabic gum were characterized before and after the extrusion process. Two treatments were do, one profile with low temperature and shear rate and other with high temperature and shear. The results of chemical composition demonstred that the fresh cashew gum had lower ash content than the trade gum arabic, indicating lower impurities. In addition, fresh cashew gum and processed cashew gum were highlighted by the high levels of soluble fiber. However, cashew gum had lower minerals's level that the gum arabic. In the viscosity profile, was observed that it was increased in the gum arabic processed samples, whereas in the cashew gum processed samples decreased. Analysis of x-ray diffraction confirmed the predominance of the amorphous chain of the two samples. Rheometry through the flow and viscosity curves allowed the characterization of the samples as pseudoplastic fluids, according to the mathematical model of Ostwald Waale. The samples showed a reduction in glass transition temperature after extrusion. By colorimetry, was observed that the color parameters of cashew gum and gum arabic were different at the 5% significance level. From the parameters and results evaluated, cashew gum could be indicated as a replacement for gum arabic. However, additional analysis are suggested. / Pa?ses tropicais, como o Brasil, s?o deposit?rios de uma grande variedade de fontes de polissacar?deos vegetais conhecidos e outros ainda n?o explorados que possuem grande potencial em aplica??es industriais, dentre os quais podemos citar a goma de cajueiro. Algumas pesquisas reportam a possibilidade do uso desta goma em v?rios setores em substitui??o ? goma ar?bica devido ? semelhan?a estrutural. Sendo assim, este estudo se prop?e a aumentar o conhecimento t?cnico-cient?fico sobre as propriedades tecnol?gicas da goma de cajueiro e compar?-la ? goma ar?bica para assegurar sua aplica??o na ind?stria de alimentos, especificamente. Para tanto, neste estudo foram realizadas an?lises de caracteriza??o da goma de cajueiro e ar?bica, antes e ap?s o processo de extrus?o. Foram realizados dois tratamentos: um perfil de baixa temperatura e cisalhamento e outro de alta temperatura e cisalhamento. Nos resultados de composi??o centesimal notou-se que a goma de cajueiro in natura apresentou menor teor de cinzas que a goma ar?bica comercial, indicando menor grau de impurezas. Al?m disso, as amostras de goma de cajueiro in natura e processadas destacaram-se pelo alto teor de fibra sol?vel, cerca de 90%. Por outro lado, a goma de cajueiro apresentou menores teores de minerais que a goma ar?bica. No perfil de viscosidade foi observado que este par?metro aumentou nas amostras de goma ar?bica processadas, enquanto, nas amostras processadas de goma de cajueiro houve redu??o. A an?lise de difra??o de raio-x confirmou a predomin?ncia de conforma??o amorfa das cadeias polim?ricas de ambas amostras. An?lises reol?gicas, por meio da curva de fluxo e viscosidade, permitiram a caracteriza??o das amostras como fluidos pseudopl?sticos, obedecendo ao modelo matem?tico de Ostwald de Waale. As amostras apresentaram redu??o na temperatura de transi??o v?trea ap?s a extrus?o. Por colorimetria foi observado que os par?metros de cor entre a goma de cajueiro e a goma ar?bica foram diferentes ao n?vel de 5% de signific?ncia. A partir dos par?metros avaliados e dos resultados obtidos, a goma de cajueiro poderia ser indicada como substituta da goma ar?bica. Entretanto, sugerem-se an?lises complementares.
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An investigation of the molecular structure, composition and biophysical properties of gum ArabicGashua, Ibrahim Babale January 2016 (has links)
Acacia senegal and Acacia seyal are important agroforestry cash crops indigenous to several countries of sub-Saharan Africa, including Nigeria. The gum exudate produced by these species is termed gum Arabic which is an approved food additive (E414), primarily used as an emulsifier. In the current study, the molecular structure, composition and biophysical properties of gum samples harvested from mature trees of Acacia senegal at two specific ecolocations in Nigeria (NG1 and NG2), have been investigated together with two previously characterised gum samples harvested from A. senegal and A. seyal originating from Sudan. The monosaccharide sugar composition analyses have shown that the A. seyal gum had a lower rhamnose and glucuronic acid content than the A. senegal gum, but had higher arabinose content. No significant difference was observed between the sugar composition of the A. senegal gums from Sudan and Nigeria. The total protein content of the Nigerian gum samples were significantly higher than recorded for the Sudanese samples. The principal amino acids present in all the gum samples are hydroxyproline, serine, aspartame, threonine and proline which is in agreement with literature values. The hydrodynamic size of the molecules present in the gums was studied using dynamic light scattering and it was found that molecular association occurred in solution over time which was inhibited in the presence of an electrolyte. The comparison of droplet size distribution for emulsions prepared with A. senegal (NG1) and A. seyal gum samples showed that A. senegal sample was a better emulsifier than the A. seyal. Multilayer adsorption of the samples onto polystyrene latex particles was observed, which resulted in an increase in thickness of the adsorbed layer as a consequence of the interaction between the protein and carbohydrate within the molecules adsorbed on the emulsion surface. Preliminary analyses of the gums using transmission electron microscopy showed the presence of varied macromolecules, ranging in size from ~12 - ~60 nm. Immuno-gold negative staining (using JIM8 monoclonal antibody) indicated clear labelling of arabinogalactan-proteins present in the gums harvested from A. senegal, the labelling of the A. seyal sample was inconclusive. In summary, the data presented represents the first detailed comparison of the structure, composition and physicochemical characteristics of Nigerian Acacia gum exudates versus Sudanese samples (main global supplier) which have shown that gum obtained from Nigerian sources is a viable alternative to ensure future supply of this valuable natural resource.
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Morphological and Physiological Responses of Senegalia senegal (L.) Britton Provenances to Drought, Salinity, and FertilitySarr, Mame Sokhna 22 May 2017 (has links)
Increasing drought and salinity tolerances in economically important trees adapted to dry land areas is key challenge for maintaining the socioeconomic welfare of dry land areas. Strategies to improve drought and salt tolerance must examine the tree physiological mechanisms that link to the trees survival and growth. This study examined physiological adaptive traits allowing Senegalia senegal to grow better in both saline and dry lands. We conducted two greenhouse experiments and one field study to characterize growth, photosynthetic capacity, water use efficiency (WUE) and gum arabic yield potential among different Senegalia senegal provenances. In the first experiment, we tested early growth and photosynthetic response of seed sources to a cyclic drought treatment. The second greenhouse study examined seed source response to drought, salinity and fertility conditions. Gum yield assessment, growth and WUE of mature trees were determined from a field trial.
In general, results showed a high intra genetic variability of Senegalia senegal on gum yield, biomass accumulation and growth. Ngane provenance presented superior growth characteristics as both mature trees and seedlings and exhibited a more conservative water use strategy under drought. Both greenhouse studies revealed similar photosynthetic capacity among Senegalia senegal genotypes when conditions are not limiting. However, when factors such as salinity, fertility and severe drought are involved, different physiological and morphological responses appear and at times this was dependent on seed source. But, at moderate drought stress (chapter 2), no drought by provenance interaction was found. Results of chapter 3 revealed that Ngane has larger stomata with low density in comparison with Diamenar and Kidira provenances. With the exception of Ng21B1, all seed sources displayed similar adaptations to salt stress in term of biomass accumulation. Fertilizer increased total biomass of all seed sources from 63% to 213% for Ng21B1 and K17B19, respectively. However, salinity reduced the fertilizer effect on biomass increment. Leaf gas exchanges were affected by salinity and fertilizer within various responses among seed sources. Results of chapter 4 revealed that gum yield was found to be positively correlated with tree height, crown width, stem volume index and crown area index. Ngane and Diamenar appeared the best provenances in term of annual gum yield per hectare. Diamenar had a higher survival rate than Ngane. This finding reveals the need to consider the tradeoff between tree survival rate and individual tree gum yield in Senegalia senegal stands. In addition to being more sensitive to salinity, Ngane also seems to be more susceptible to low soil pH in terms of survival, but this result needs to be tested further.
This study suggests that improvement of gum arabic production can be possible through genetic selection. But, for the best adapted genotypes, research should explore new genetic combination and investigate physiology and genetic diversity. Moreover, the findings on the relationship between soil pH and tree survival rate suggests a need for care in selecting appropriate sites for Senegalia senegal stands. Therefore, silviculture practices as well as genetic selection appear critical in improving gum arabic production. / Ph. D.
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Associative phase separation in admixtures of pea protein isolates with gum Arabic and a canola protein isolate with i-carrageenan and alginateKlassen, Darlene Renae 28 June 2010
The overall goal of this thesis is to better understand mechanisms governing associative phase separation within admixtures of plant proteins (e.g., pea and canola) and anionic polysaccharides (e.g., gum Arabic, alginate or é-carrageenan). The process involves the electrostatic attraction between two biopolymers of opposing charges, and typically results in the formation of both soluble and insoluble complexes during an acidic pH titration. If successful, polysaccharides could be triggered to coat the proteins surface to give novel, and hopefully improved functionality as ingredients for food and biomaterials.<p>
In the first study, the effect of protein enrichment and pH on the formation of soluble and insoluble complexes in admixtures of pea legumin (Lg) and vicilin (Vn) isolates with gum Arabic (GA) was investigated by turbidimetric, surface charge and fluorometric measurements. The solubility of the protein isolates and mixed biopolymer systems was also studied as a function of pH. Enrichment of the crude Lg and Vn isolates by low pressure liquid chromatography led to a shift towards higher pHs at the onset of soluble complex formation in the presence of GA for both protein isolates, whereas the onset of insoluble complex formation was unaffected. Complexation of the Lg (or Vn) isolates with GA resulted in a shift in the pH where neutrality (zeta potential = 0 mV) occurred to lower pH values, relative to the Lg (or Vn) isolates alone. In the case of the enriched Vn isloate, changes to its tertiary structure were observed by fluorometry upon complexation with GA, whereas no changes were found for the enriched Lg isolate. Complexation of Lg and Vn isolates with GA also had little effect on their solubilities relative to protein alone solutions.<p>
In the second study, the formation of soluble and insoluble complexes, and the nature of their interactions as determined by optical density analysis, were investigated in admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and é-carrageenan) as a function of pH and biopolymer weight mixing ratio. The solubilities of formed complexes were also investigated versus protein alone. In both CPI-polysaccharide systems, critical pH associated with the onset of soluble and insoluble complexes shifted to higher pHs as the mixing ratios increased from 1:1 to 20:1 (CPI:polysaccharide), and then became constant. There complexes formed primarily through electrostatic attractive forces with secondary stabilization by hydrogen bonding. The solubilities of the CPI-alginate complexes were significantly enhanced relative to CPI alone or CPI-é-carrageenan, which were similar.
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Associative phase separation in admixtures of pea protein isolates with gum Arabic and a canola protein isolate with i-carrageenan and alginateKlassen, Darlene Renae 28 June 2010 (has links)
The overall goal of this thesis is to better understand mechanisms governing associative phase separation within admixtures of plant proteins (e.g., pea and canola) and anionic polysaccharides (e.g., gum Arabic, alginate or é-carrageenan). The process involves the electrostatic attraction between two biopolymers of opposing charges, and typically results in the formation of both soluble and insoluble complexes during an acidic pH titration. If successful, polysaccharides could be triggered to coat the proteins surface to give novel, and hopefully improved functionality as ingredients for food and biomaterials.<p>
In the first study, the effect of protein enrichment and pH on the formation of soluble and insoluble complexes in admixtures of pea legumin (Lg) and vicilin (Vn) isolates with gum Arabic (GA) was investigated by turbidimetric, surface charge and fluorometric measurements. The solubility of the protein isolates and mixed biopolymer systems was also studied as a function of pH. Enrichment of the crude Lg and Vn isolates by low pressure liquid chromatography led to a shift towards higher pHs at the onset of soluble complex formation in the presence of GA for both protein isolates, whereas the onset of insoluble complex formation was unaffected. Complexation of the Lg (or Vn) isolates with GA resulted in a shift in the pH where neutrality (zeta potential = 0 mV) occurred to lower pH values, relative to the Lg (or Vn) isolates alone. In the case of the enriched Vn isloate, changes to its tertiary structure were observed by fluorometry upon complexation with GA, whereas no changes were found for the enriched Lg isolate. Complexation of Lg and Vn isolates with GA also had little effect on their solubilities relative to protein alone solutions.<p>
In the second study, the formation of soluble and insoluble complexes, and the nature of their interactions as determined by optical density analysis, were investigated in admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and é-carrageenan) as a function of pH and biopolymer weight mixing ratio. The solubilities of formed complexes were also investigated versus protein alone. In both CPI-polysaccharide systems, critical pH associated with the onset of soluble and insoluble complexes shifted to higher pHs as the mixing ratios increased from 1:1 to 20:1 (CPI:polysaccharide), and then became constant. There complexes formed primarily through electrostatic attractive forces with secondary stabilization by hydrogen bonding. The solubilities of the CPI-alginate complexes were significantly enhanced relative to CPI alone or CPI-é-carrageenan, which were similar.
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Integration of remote sensing and GIS in studying vegetation trends and conditions in the gum arabic belt in North Kordofan, SudanAdam, Hassan Elnour 18 April 2011 (has links) (PDF)
The gum arabic belt in Sudan plays a significant role in environmental, social and economical aspects. The belt has suffered from deforestation and degradation due to natural hazards and human activities. This research was conducted in North Kordofan State, which is affected by modifications in conditions and composition of vegetation cover trends in the gum arabic belt as in the rest of the Sahelian Sudan zone. The application of remote sensing, geographical information system and satellites imageries with multi-temporal and spatial analysis of land use land cover provides the land managers with current and improved data for the purposes of effective management of natural resources in the gum arabic belt. This research investigated the possibility of identification, monitoring and mapping of the land use land cover changes and dynamics in the gum arabic belt during the last 35 years. Also a newly approach of object-based classification was applied for image classification. Additionally, the study elaborated the integration of conventional forest inventory with satellite imagery for Acacia senegal stands. The study used imageries from different satellites (Landsat and ASTER) and multi-temporal dates (MSS 1972, TM 1985, ETM+ 1999 and ASTER 2007) acquired in dry season (November). The imageries were geo-referenced and radiometrically corrected by using ENVI-FLAASH software. Image classification (pixel-based and object-based), post-classification change detection, 2x2 and 3x3 pixel windows and accuracy assessment were applied. A total of 47 field samples were inventoried for Acacia senegal tree’s variables in Elhemmaria forest. Three areas were selected and distributed along the gum arabic belt. Regression method analysis was applied to study the relationship between forest attributes and the ASTER imagery. Application of multi-temporal remote sensing data in gum arabic belt demonstrated successfully the identification and mapping of land use land cover into five main classes. Also NDVI categorisation provided a consistent method for land use land cover stratification and mapping. Forest dominated by Acacia senegal class was separated covering an area of 21% and 24% in the year 2007 for areas A and B, respectively. The land use land cover structure in the gum arabic belt has obvious changes and reciprocal conversions between the classes indicating the trends and conditions caused by the human interventions as well as ecological impacts on Acacia senegal trees. The study revealed a drastic loss of Acacia senegal cover by 25% during the period of 1972 to 2007.The results of the study revealed to a significant correlation (p ≤ 0.05) between the ASTER bands (VNIR) and vegetation indices (NDVI, SAVI, RVI) with stand density, volume, crown area and basal area of Acacia senegal trees. The derived 2x2 and 3x3 pixel windows methods successfully extracted the spectral reflectance of Acacia senegal trees from ASTER imagery. Four equations were developed and could be widely used and applied for monitoring the stand density, volume, basal area and crown area of Acacia senegal trees in the gum arabic belt considering the similarity between the selected areas. The pixel-based approach performed slightly better than the object-based approach in land use land cover classification in the gum arabic belt. The study come out with some valuable recommendations and comments which could contribute positively in using remotely sensed imagery and GIS techniques to explore management tools of Acacia senegal stands in order to maintain the tree component in the farming and the land use systems in the gum arabic belt.
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