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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

Effect of mycotoxigenic microorganisms on palm fruits and palm oil produced at the cottage industry level

Tagoe, Sheila M. A. January 2008 (has links)
Oilseeds are e the group of crops that store energy in the form of oil. Tliey form a ery important component of tropical agriculture, because they are readily available and provide highly nutritious human and animal food. The oilseeds also irve as an important source of energy and act as carriers of fat-soluble vitamins. About 71 percent of edible oils and fats are derived from plant sources as oilseeds. Tecnnological advances have made it possible for one processing of non-food products using oilseeds as raw material. About forty different oilseeds are reported to have the potential for food uses but the most significant ones in the world's edible / non-edible oil supply include coconut, corn, cotton, oil palm, peanut, rapeseed, rice, safflower, sesame, soybean and sunflower. To achieve the objectives of the study, various preparatory experiments were conducted using molecular biology methods. Results obtained showed that DNA extraction from palm fruits and oil samples was successful with different methods being optimal for different materials; glass beads for pelleted microbes derived from oil palm fruit surface washes, liquid nitrogen for microbial cultures and Proteinase K for oil samples. Results on the free fatty acid and microbial contamination of the samples also showed that the good-grade oils contain microbes some of which may have the potential of producing toxin.
2

Physicochemical characterisation of sunflower seed oil bodies ex-vivo

Fisk, Ian January 2007 (has links)
Oilseeds store energy as triacylglycerides during periods of dormancy in preparation for germination and the early stages of development. The triacylglyceride is stored in discrete organelles termed oil bodies. Oil bodies are formed during the synthesis of neutral lipids within the bilayer of cellular endoplasmic reticulum (ER); as lipid is synthesised it forms droplets of oil that swell distending the ER membrane and at a critical diameter separate from the ER by vesiculation forming independent organelles. These organelles are structurally stabilised by a phospholipid monolayer originating from the ER and the addition of highly amphiphilic oleosin proteins. Oil bodies have been shown previously to be extremely stable organelles that can be easily extracted and purified from oilseeds; our aim was to develop an understanding of the physical and chemical properties of sunflower oil bodies ex-vivo prior to their subsequent use in commercial products. Several novel findings were elucidated through this work: oil body phytochemical composition, their physical and oxidative stability and their ability to store and deliver flavour compounds. It was hypothesised that tocopherol is tightly associated with sunflower oil bodies. This was tested by recovering oil bodies from sunflower seed and washing them to remove extraneous proteins and associated phenolic compounds. Tocopherol remained with washed oil bodies (392 mg tocopherol.kg-1 oil body oil) and this population of tocopherol represented 38% of the total seed tocopherol. It was hypothesised that this high tocopherol concentration and its intrinsic association to oil body structures would contribute to an increased level of oxidative stability. Sunflower seed lipids were significantly more resistant to thermally induced oxidation when stabilised in oil body suspensions compared to sunflower oil emulsions stabilised by a range of commercial emulsifiers (sodium dodecyl sulfate, polyoxyethylenesorbitan monolaurate (tween 20) and dodecyltrimethylammonium bromide). Oxidative stability was assessed through lipid hydroperoxide concentration and the concentration of headspace hexanal. Maximum lipid hydroperoxide concentration in surfactant stabilised emulsions after 8 days at 45oC ranged between 26 and 333 mmol lipid hydroperoxide.kg-1 oil whereas lipid hydroperoxide concentrations in oil body suspensions did not exceed 12 mmol lipid hydroperoxide.kg-1 oil. In addition there was no development in oxidative rancidity over the 8 day storage trial of oil bodies stored at 5oC. The composition of phospholipids in a range of oil body preparations was assessed; purified oil bodies contained principally phosphatidylcholine (91%) and a smaller fraction of phosphatidylethanolamine (9%). Less purified preparations contained other phospholipid species; the presence of which was explained by contamination with either non-intrinsic cellular phospholipids or phospholipase D that catalysed the breakdown of phospholipids to phosphatidic acid. Mechanisms and the extent of oil body physical stability were assessed using charge analysis and resistance of oil body preparations to changes in temperature and pH. Oil bodies are stabilised by a combination of steric hindrance and electrostatic repulsion provided by the surface proteins and phospholipids. Oil bodies had a zeta potential of -30mV at neutral pH and the surface charge was pH dependant with an apparent isoelectric point of between pH3 and pH6 was calculated from electrophoretic mobility, streaming potential and creaming stability measurements. Purified oil bodies were physically stable to thermal stresses up to 45oC for 2 days, although less purified preparations lost structural integrity at temperatures above 25oC. When assessed for their ability to delivery flavour molecules, oil bodies had comparable bulk phase properties to artificial emulsions stabilised by tween 20. Oil bodies did show a greater rate of flavour delivery during headspace dilution, when compared with the model artificial emulsions, suggesting commercial benefits may be gained through the incorporation of oil bodies into commercial emulsions. The key findings of this work are that oil bodies are extremely stable organelles that are resistant to thermal stress and physical processing. When lipid is stored within oil bodies it has greater resistance to the onset of lipid oxidation which may be explained by the intrinsic association of phospholipids, proteins and phytochemicals (vitamin E).
3

Πειραματική καλλιέργεια ηλίανθου σε υπόστρωμα τέφρας με στόχο την εκτίμηση περιβαλλοντικών συνθηκών

Αναστασίου, Δημήτριος 02 February 2011 (has links)
Πραγματοποιήθηκε πείραμα με στόχο τη μελέτη των περιβαλλοντικών συνθηκών πειραματικής καλλιέργειας ηλίανθου σε υπόστρωμα τέφρας. Για την μελέτη του θέματος εγκαταστάθηκε πειραματικός αγρός στην παραλιακή περιοχή του χωριού Μηλάκι του δήμου Ταμυνέων (Αλιβερίου) στο νομό Ευβοίας. Η σπορά του ηλίανθου έγινε με την φύτευση σπόρου με το χέρι στις 27 Απριλίου του 2009 σε δυο διαφορετικά υποστρώματα, της ήδη υπάρχουσας στην περιοχή, τέφρας και σε κανονικό εδαφικό υπόστρωμα το οποίο μεταφέρθηκε στην περιοχή. Για τις ανάγκες του πειράματος χρησιμοποιήθηκαν και στα δυο υποστρώματα τα πιο κάτω εδαφοβελτιωτικά (γύψος, τύρφη, περλίτης, πριονίδι) καθώς και αναμείξεις αυτών. Η μέγιστη τιμή του ολικού ύψους των φυτών στο υπόστρωμα της τέφρας, παρατηρείται στις 18 Ιουλίου του 2009, ενώ για την παράμετρο της διαμέτρου των ανθοκεφαλών η μέγιστη τιμή της παρατηρείται στις 2 Αυγούστου του 2009. Τα ίδια συμπεράσματα προκύπτουν και από τα δεδομένα που ελήφθησαν από το κανονικό εδαφικό υπόστρωμα. Υπολογίστηκαν οι συντελεστές συσχέτισης των φυτικών παραμέτρων στα διάφορα πειραματικά πεδία. Αυτές έδειξαν ότι οι θετικές αλλά και οι αρνητικές συσχετίσεις μεταξύ των ίδιων συγκρινόμενων παραμέτρων (Μεσοδιάστημα Κοτύλη – 1ο φύλλο, Μεσοδιάστημα 1ο φύλλο – 2ο φύλλο, Ολικό ύψος, Φυλλική επιφάνεια 1ου φύλλου, Φυλλική επιφάνεια 2ου φύλλου, Διάμετρος ανθοκεφαλής, Βάρος φυτού), είναι μεγαλύτερες στο υπόστρωμα της τέφρας από αυτό του κανονικού εδαφικού υποστρώματος. Εξαίρεση αποτελούν δυο περιπτώσεις, όπου στο υπόστρωμα της τέφρας εμφανίζεται αρνητική συσχέτιση ενώ στο κανονικό εδαφικό υπόστρωμα εμφανίζεται θετική συσχέτιση. Διαπιστώθηκε ότι στο υπόστρωμα της τέφρας, οι μεγαλύτερες τιμές των παραμέτρων που μετρήθηκαν κατά τη διάρκεια του πειράματος παρατηρήθηκαν στα πειραματικά τετράγωνα με τα παρακάτω εδαφοβελτιωτικά: T5A, G.T4A, G.T5A, G.T.PL3A και G.T.PL4A. Στο κανονικό εδαφικό υπόστρωμα, διαπιστώθηκε ότι οι μεγαλύτερες τιμές των παραμέτρων που μετρήθηκαν κατά τη διάρκεια του πειράματος παρατηρήθηκαν στα πειραματικά τετράγωνα με τα παρακάτω εδαφοβελτιωτικά: G.T5B, G.T.PL4B, G.T.PL5B, G.T.PL.PN4B και G.T.PL.PN5B. / An experiment was realised amining at the study of environmental conditions experimental growing of sunflower in sublayer of ash. For the study of this subject was installed experimental field in the coastal region of the village Milaki at the municipality Tamyneon (Aliveriou) in the prefecture of Evia. The seeding of sunflower became with the planting of seed by hands on 27 April 2009 in two different sublayers, the already existing in the region, ash and in regular territorial sublayer which was transported in the region. For the needs of experiment they were also used in the two sublayers the below ameliorative of ground (gypsum, peat, perlite, sawdust) as well as mixtures of these. The biggest price of the total height of plants in the sublayer of ash, is observed on 18 July 2009, while for the parameter of heads diameter her biggest price is observed on 2 August 2009. The same conclusions also result from the data that were received from the regular territorial sublayer. They were calculated the correlation factors of the plant parameters in the various experimental fields. These showed that positive but also negative correlations between the same compared parameters (Cotyledon – first leaf interval, First leaf – second leaf interval, Total height, Leaf surface of first leaf, Leaf surface of second leaf, Head diameter, Weight of plant) are bigger in the sublayer of the ash from that of the regular territorial sublayer. Exception constitutes two cases, where in the sublayer of ash is presented negative correlation while in the regular territorial sublayer is presented positive correlation. It was realised that in the sublayer of ash, the biggest prices of the parameters that were measured at the duration of experiment were observed in the experimental squares with the following ameliorative of ground: T5A, G.T4A, G.T5A, G.T.PL3A και G.T.PL4A. In the regular territorial sublayer, was realised that the biggest prices of the parameters that were measured at the duration of experiment were observed in the experimental squares with the following ameliorative of ground: G.T5B, G.T.PL4B, G.T.PL5B, G.T.PL.PN4B και G.T.PL.PN5B.
4

Valorisation chimique de la biomasse oléagineuse d’origine béninoise : Lophira lanceolata et Carapa procera / Chemical enhancement of the oleaginous biomass from Benin : Lophira lanceolata and Carapa procera

Nonviho, Guévara 22 April 2015 (has links)
Lophira lanceolata (Ll) et Carapa procera (Cp) sont des plantes oléagineuses, peu étudiées. Au Bénin, elles sont pourtant utilisées à des fins alimentaires, cosmétiques et thérapeutiques. Cette étude vise la caractérisation de leurs graines, coques et bois. Les huiles végétales de Ll ont été obtenues par différentes méthodes dont une aqueuse traditionnelle tandis que celle de Cp l’a été par utilisation d’hexane. De façon générale, les huiles de Ll montrent un profil nutritionnel riche en acides gras polyinsaturés (>50% m/m: masse pour masse). Outre ses propriétés chimiques meilleures, celle obtenue par le procédé traditionnel est plus riche en acides gras essentiels, en composés phytostéroliques comme le lupéol et en tocols. La torréfaction et l’utilisation d’enzymes ont également permis d’évaluer l’impact de ces méthodes sur la composition chimique des graines de Ll. Quant aux graines de Carapa p., elles présentent un profil plutôt abondant en acides gras monoinsaturés, en tocotriénols (85,56% m/m) et en lanostérols (28,03%, m/m). Les tourteaux, coques et bois des deux espèces montrent une variabilité chimique en composés pariétaux (extractibles, hémicelluloses, celluloses et lignines). Une caractérisation in fine des hémicelluloses de ces parties des deux plantes a permis de montrer qu’elles sont essentiellement de type glucuronoxylanes. Les extractibles de ces plantes ont également offert une large gamme de composés à connotations industrielles et pharmaceutiques positives. Enfin, les conditions optimales de la biosorbption du bleu de méthylène sur les coques de Lophira ont également été évaluées. Cette évaluation a permis de mettre en exergue la potentielle utilisation de ces résidus agroforestiers pour rendre potables les eaux usées industrielles / The chemical composition of wild oilseeds, such as Lophira lanceolata (Ll) and Carapa procera (Cp) of Benin is mostly unknown. Yet they undergo crafted transformations for food, cosmetic and therapeutic purposes. This study aims to characterize their seeds, hulls and woods. From these crops, different oils have been extracted. One of them has been produced in rural area according to aqueous ancestral method. On the whole, oils of Ll have presented an interesting nutritional profile. They are rich in polyunsaturated fatty acids (> 50% m/m: mass for mass), especially that extracted by artisanal process. Beyond its good chemical properties, it provides essential fatty acids, phytosterols such as lupeol and more tocols compounds. Roasting and the use of enzymes have also assessed the impact of these methods on the chemical composition of LI seeds. Differently, Cp oil’s has an abundant presence of MUFA, tocotrienols (85.56% w/w) and the richest composition in lanosterol (28.03%, m/m). The seeds cakes, hulls and wood of both species showed various distributions on chemical components (extractives, hemicellulose, cellulose and lignin). The characterization of hemicelluloses from different parts of plants has shown that they are essentially glucuronoxylans type. Extractives also offered a wide range of compounds mostly appreciated for industrial and pharmaceutical purposes. The chemical composition of the shells of Lophira was rich in organic compounds such as lignin (32.13%, dry weight) so their biosorbent capacity was evaluated. They showed methylene blue good adsorption capacity in aqueous solution, which highlighted their potential use in the purification of wastewater

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