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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Förädling av stjälkfibrer för fler naturliga fiberalternativ : Enzymbehandling för avlägsnande av pektin i stjälkfibrer för ökad spinnbarhet. / Processing of bast fibres with pectate lyase

Larsson, Malin, Nilsson, Annie January 2015 (has links)
Grewia optiva är en utav många outnyttjade stjälkfibrer som skulle kunna bidra till ökandet utav de naturliga fiberalternativen. Fibern har idag inte så många användningsområden på grund utav dess hårda och styva uppbyggnad, vilket gör den svår att spinna till garn. På uppdrag av organisationen Bhartiya Gramotthan Sanstha (BGS) har i detta projekt en redan befintlig metod utvecklats för att förädla fibern. Vad som främst eftersöktes var nedbrytandet av pektin som är en av de faktorer som bidrar till fiberns hårda och styva struktur. I metoden användes biologiskt nedbrytbara enzym som katalysatorer. En fungerande metod skulle kunna öka användningsområdet hos stjälkfibrer generellt och öka möjligheten till användandet utav fler naturliga fibrer. Enzymet som har använts i metoden är ett pektatlyas EC 4.2.2.2 som katalyserar reaktionen som sker då pektinmolekyler klyvs. För att effektivisera processen adderades en komplexbildare, EDTA, som tidigare visat goda resultat för lin. Efter enzymbehandlingen skedde en viktreduktion av fibrerna samt förändring av deras utseende. I svepelektronmikroskop observerades förändring av ytstruktur samt separation mellan fiberbuntarna. Dessa parametrar är viktiga och har stor inverkan på spinnbarheten hos fibrer. I projektet har försök att spinna fibern gjorts men inte lyckats helt. Förändringen på ytstruktur och separation mellan fibrerna tyder dock på att behandlingen är ett steg i rätt riktning. / Grewia optiva is one of many unused bast fibres that could contribute to an increase of natural textile fibres on the industrial market. This fibre has to-day not as many applications due to its stiff and hard structure that makes the fibre difficult to spin into yarn. On behalf of the organisation Bhartiya Gramotthan Sanstha (BGS) has an existing method been developed to process the Grewia optiva fibre. The method is developed to break down substances like pectin that is responsi-ble for the hard and stiff structure of the fibre. Degradable biological en-zymes were used as catalyser in the method. With a functioning method like this the applications of bast fibres could increase and contribute to the use of more natural fibres. The enzyme used to catalyse the chemical reaction and the cleavage of pec-tin molecules in this method was a pectate lyase EC 4.2.2.2. In this method EDTA was used as a chelator to efficient the chemical process. EDTA has been used as a chelator in earlier reports and showed good results. After the enzymatic treatment a weight reduction of the fibre was notable. In SEM-analysis separation between fibres and changes on the fibre surfaces was observed. These parameters are important and affect the spinning capability of the fibre. To test the spinning capability of the enzyme treated fibre they were spun in a ring spinning system, unfortunately not successfully. The surface changes and the separation shows that the enzymatic treatment had occurred and indicates that the method has developed in the right direction.
2

Isolation and Structure Elucidation of Antiproliferative Agents From Madagascar Rainforests

Karkare, Sampada S. 31 October 2007 (has links)
Through our continuing search for anticancer agents from Madagascar rainforests as a part of International Cooperative Biodiversity Group (ICBG), we received two extracts which were active against the A2780 human ovarian cancer cell line and hence were selected for further fractionation. Six compounds were isolated from these extracts. The structure elucidation and characterization of these compounds was carried out using mass spectrometry and 1D and 2D NMR techniques. The bioassay-guided fractionation of Roupellina (Strophanthus) boivinii yielded three new and one known cardenolide glycosides. The structure of the known cardenolide glycoside was determined after comparison of NMR data to that found in literature for digitoxigenin 3-O-β-D-glucopyranosyl-(1â 4)-α-L-acofriopyranoside. All four compounds exhibited good antiproliferative activity on the A2780 bioassay. The fractionation of the extract of Grewia sp. led to the isolation of one new and one known triterpenoid. The known triterpenoid was identified as 7β-hydroxy-23-deoxojessic acid and its structure was confirmed by comparison of its 1D and 2D NMR data to that found in literature. / Master of Science
3

Optimisation de l'utilisation du taro (Colocasia esculenta) variété lamba en panification par l'usage de la gomme Grewia mollis. Juss (Famille Tiliaceae) / Optimization the use of taro (Colocasia esculenta) lamba variety in breadmaking by the gum of Grewia mollis (tiliaceae family)

Panyoo Akdowa, Emmanuel 17 September 2014 (has links)
Le problème dans cette étude est celui de l’incorporation de la gomme Grewia mollis dans le mélange blé-taro avec pour objet d’améliorer le taux de substitution du blé par la farine de taro qui, selon la littérature, ne peut dépasser de valeurs allant de 10 à 15 % sans altérer de façon considérable la qualité de la pâte de pain. Les objectifs définis dans cette étude sont triples : (1) d’abord connaitre les propriétés de la farine de taro variété Lamba qui, avant cette étude n’a pas fait l’objet d’études antérieures. (2) Déterminer les conditions optimales d’extraction de la gomme Grewia, dont on connait de la littérature les caractéristiques physicochimiques et fonctionnelles et pas les meilleures conditions d’extraction. (3) Etudier dans un plan de mélange à trois composantes l’effet du pourcentage de gomme, de farine de taro et blé sur les propriétés rhéologiques et sensorielles de la pâte et du pain. Dans cette étude les méthodes usuelles de caractérisation ont été utilisées. Pour l’objectif 1, le dispositif expérimental prend en compte la taille du tubercule (4 modalités) comme facteurs, et les paramètres mesurés sont : la composition proximale, la granulométrie et la forme de particules, les propriétés thermiques et rhéologiques de la farine. Pour l’objectif 2, la gomme est extraite selon un plan composite centré à faces centrées avec comme facteurs le ratio volume d’eau sur masse de la poudre de l’écorce, la température et le temps d’extraction, et les réponses sont la viscosité de la solution et le taux d’extraction. Une caractérisation du profil de sucres de la gomme a été faite. Pour l’objectif 3, un plan de mélange ternaire Grewia-taro-blé à contraintes a été effectué. Le volume de pousse de la pâte, le test de double morsure, le test du fluage-recouvrement ont été mesurés sur la pâte, alors que les pains obtenus ont fait l’objet d’une analyse du test de double compression et d’acceptabilité. Les résultats de l’objectif 1 ont montré que la composition physicochimique du taro varie en fonction de la masse et du pelage, le profil en acide aminé présente une absence des acides aminés soufrés. Les résultats de l’extraction de la gomme dans l’objectif 2 ont montré que seul le ratio augmente significativement la viscosité et le rendement d’extraction de la gomme. Les conditions optimales d’extraction de la gomme Grewia mollis sont les suivantes: pH: 7,1 temps : 1h température: 73,1 °C ratio eau / poudre : 55,4 / 1, pour une viscosité de 0,98 Pa.s et un rendement de 0,32%. Les résultats de l’objectif 3 montrent que l’augmentation de la gomme Grewia mollis entraine une augmentation de la capacité d’absorption d’eau des farines mélangées, une augmentation de la viscoélasticité, du volume de pousse, du volume de pain, de l’acceptabilité générale jusqu’à un seuil de 2,5% puis une baisse est observée. Les analyses de corrélation ont montré que l’augmentation de la capacité d’absorption d’eau entraine une baisse des paramètres du fluage et du recouvrement de la pâte, du volume de pousse / The problem in this study is the incorporation of Grewia gum in the wheat-taro mixture in order to improve the level of substitution of wheat flour by taro flour which, according to the literature, cannot exceed 10-15% without deteriorating in a considerable manner the quality of the bread paste. The objective defined in this study is threefold : (1) to know the properties of the flour of taro Lamba variety which, before this study have not been the object for research (2) to determine the optimum conditions for extraction of the Grewia gum, with known physico-chemical and functional characteristics but no standard for conditions extraction. (3) To study the effect of the percentage of gum, taro flour and wheat flour on the rheological and sensory properties of the paste and the bread using a mixture designs with three components. In this study the usual methods of characterization were used. For objective 1, the experimental device takes into account sizes of tuber (4 weight) like factors, and the measured parameters are: the proximate composition, the granulometry and the shape of particles, thermal and rheological properties of the flour. For objective 2, the gum is extracted using a central composite design with faces centered with factors like the flour water ratio (w / w), the temperature, extraction time and pH, the response were the viscosity of the solution and the yield of extraction. A characterization of the sugar profile of gum was made. For objective 3, a ternary mixture design Grewia - taro-wheat with constraints was carried out. The volume of dough, the rheology of paste, the double bite test, the creep-recovering test were measured on the dough, whereas a double compression test analysis and acceptability were carried out on the bread. The results of objective 1 showed that the physico-chemical composition of the taro varies as a function of the mass and peeling type, the amino acid profile reveals the absence of sulphur amino acids. The results of the extraction of gum showed that only the ratio significantly increases the viscosity and the yield of the gum.The optimum conditions for extraction of the Grewia gum are as follows:pH: 7.1 times : 1h temperature: 73 °C water / powder ratio: 55.4 / 1, for a viscosity of 0.98 Pa.s and and yield of 0.32 %. The results of objective 3 show that the incorporation of gum increase the water absorption capacity, viscoelasticity of the dough, volume of the dough and even volume of bread. However the sensory analysis showed that the addition of gum up to 5% contributed to the rejection of the breads

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