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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.
351

Responses of nectarines to atmospheres containing high carbon dioxide concentrations

Uthairatanakij, Apiradee, University of Western Sydney, College of Science, Technology and Environment, School of Science, Food and Horticulture January 2003 (has links)
Nectarines suffer low temperature disorders (LTD)when stored for more than 2 - 3 weeks at temperatures below 8 degrees C. LTD take the form of flesh bleeding and browning, loss of juiciness, development of mealiness and failure to ripen normally.It has been shown previously that adding about 15% CO2 to the storage atmosphere at 0 degrees C can delay the development of LTD in some cvv. of peaches and nectarines. The initial aim of this research was to explore the genetic basis of the differences among cultivars in the responses to high CO2.After much investigation, it was shown that both genetic and seasonal factors are involved in the development of LTD in nectarines. The development of LTD is a form of chilling injury since they only occur at temperatures below 8 degrees C. but there was no evidence of of a direct role for ethylene in either causing or delaying LTD. It was proposed that storage at low temperatures causes a metabolic imbalance resulting from changes in the amounts or activities of proteins associated with normal ripening. Proposals were presented to further examine protein expression using storage conditions that affect the rate of development of LTD. / Doctor of Philosophy (PhD)
352

Fruit-tree borer (Maroga melanostigma) : investigations on its biological control in prune trees

Marte, Susan Plantier, University of Western Sydney, College of Health and Science, Centre for Plant and Food Science January 2007 (has links)
Fruit-tree borer, Maroga melanostigma (Wallengren), is a native Australian pest in many species of trees. It is of particular economic importance in prune (Prunus domestica) trees because the presence of this wood boring insect can reduce productivity by an average of 5% per tree. Large areas of orchards can be affected. There are currently no chemicals registered for control of this pest. Young, New South Wales is the second largest prune-growing district in Australia and the area most seriously affected by M. melanostigma. Prune growers in the district utilise integrated pest management and were supportive of a project to investigate biological control options for this economically damaging pest. The two main objectives of the project were 1) to understand the life cycle of M. melanostigma, so biological controls could be timed appropriately; and 2) to investigate biological control options for this pest. Life cycle studies were commenced in the first season (2003/04) using field cages and light trapping. These investigations continued throughout the project. In Young, moths were found to emerge from wood over a two month period (December and January). Oviposition was assumed to be during this period however, even after extensive searches of trees, no eggs were observed. Historical data were collated to determine locations and timings of moth emergence elsewhere in Australia. The data showed that M. melanostigma has been found in every state and territory Australia, with moths observed from October through to March. The biological control options reviewed were egg parasitoids (Trichogramma species only), entomopathogenic nematodes and entomopathogenic fungi. Trichogramma were favoured because of previous research undertaken against the same pest in pecans in Moree, NSW. Entomopathogenic nematodes were also investigated due to research indicating their effectiveness in cryptic situations, such as borer tunnels in trees. Fungi were considered but dismissed due to lack of literature supporting their effectiveness in reducing lepidopteran pest damage in trees. A major field trial was designed with the assistance of a biometrician and the trial blocks laid out based on this advice. There were three trial sites, each containing four blocks of approximately 200 trees (~800 trees/site). Two blocks were designated as release blocks and two as non-release blocks to correspond with the trial’s two treatments. In the first season (2003/04) an initial visual assessment of borer damage was undertaken after leaf fall on each of the trees in the trial. This information was used as baseline data, to compare against damage levels following biological control releases in the second and third years of the project. Natural parasitism in the field was assessed using cultured eggs of Helicoverpa armigera (Hübner) before and between Trichogramma carverae (Oatman and Pinto) releases. Temperature and relative humidity were recorded in each of the trial sites, for the duration of the trial, using commercially available data loggers. In the second season (2004/05), Trichogramma releases were made during the period of moth activity and H. armigera eggs were used to monitor parasitism in the trial orchards. Parasitised eggs were reared through and all parasitoids were identified as T. carverae. Damage assessments were again carried out after leaf fall to compare release versus non-release blocks, as well as to determine if there was any change in borer activity. Early instar larvae were collected from non-trial blocks and exposed to the entomopathogenic nematode Steinernema carpocapsae in a laboratory investigation. Results from this limited bioassay were inconclusive. In the third season (2005/06), Trichogramma releases were again made during the period of moth activity and H. armigera eggs were used to monitor parasitism in the trial orchards. Parasitised eggs were reared through to emergence. The emerged parasites were identified as T. carverae, T. pretiosum and T. nr brassicae. Damage assessments were again made of all the trees in the trial. Results were statistically analysed to detect any differences between treatments. There was no statistically significant evidence that the releases of T. carverae reduced damage from M. melanostigma over the duration of the trial. Although damage increased across both release and non-release treatments in most blocks during the trial investigations, the increase was slightly lower in trees in which Trichogramma had been released. It should be noted that the experiments were affected by serious drought conditions which prevailed during the three seasons of the trial. / Master of Science (Hons)
353

Caractérisation comparative de la pectine obtenue par extraction acide à partir de résidus de fruit de la passion (Passiflora edulis) et optimisation de la qualité par plan d'expériences

Giovanetti Canteri, Maria Helene 23 February 2010 (has links) (PDF)
Les substances pectiques, polysaccharides du groupe des fibres alimentaires, sont largement utilisées comme agents gélifiants et stabilisants dans l'industrie alimentaire. Le principal procédé industriel pour l'obtention de la pectine est basé sur la solubilisation de la protopectine du marc du pomme ou du péricarpe d'agrumes, réalisée dans des conditions faiblement acide à chaud. Des travaux récents ont montré l'extraction de pectine de nouvelles matières premières et en utilisant différentes conditions, qui influencent le rendement et la qualité du produit final. Le Brésil est le plus grand producteur et consommateur mondial de fruit de la passion et les résidus de l'industrie du jus sont encore sous-utilisées. Ces écorces pourraient être une matière première alternative pour l'extraction de pectine. La quantité de ce sous-produit par année pourrait atteindre 300 mille tonnes, avec un potentiel de production de 2 mille tonnes de pectine. Le principal objectif de ce travail était d'établir un protocole d'extraction permettant de produire des pectines de qualité à partir d'écorce de fruit de la passion jaune. La caractérisation du résidu produit par les industries est la clé pour augmenter la valeur de ces produits. Ainsi, la composition des différentes fractions tissulaires de l'écorce de fruit de la passion jaune a été mesurée, ainsi que celle de la pectine extraite. Les fibres alimentaires sont le principal composant du péricarpe de fruit de la passion jaune, avec des valeurs proches de 60%, sauf pour la fraction endocarpe, la plus riche en protéines de toutes les fractions analysées. En ce qui concerne la qualité de la pectine extraite, c'est le mésocarpe qui donne les rendements les plus élevés (136 g Kg-1) avec une viscosité plus forte et une teneur en composés phénoliques totaux résiduels la plus faible (15%). La composition moyenne de cette fraction était de 3,1% de protéines; 0,6% de matières grasses ; 7,1% de cendres; 66,1% de fibres alimentaires totales ; 127 g Kg-1 de composées phénoliques, 23% de carbohydrates disponibles, 6,10% d'humidité et une valeur calorique de 242 Kcal par 100 g de produit. Les principaux composants des polysaccharides y sont le glucose (297 mg g-1), l'acide galacturonique (210 mg g-1), le xylose (32 mg g-1), le mannose (32 mg g-1) et le galactose (28 mg g-1). La pectine extraite à 80 ºC pendant 20 minutes avec 50 mm d'acide nitrique, pour un rapport liquide:solide de 1:50 (w/v) présente un degré d'estérification de 79% et de méthylation de 82%. Les pectines ont été extraites dans ces mêmes conditions de péricarpe de fruit de la passion commercial ou préparé au laboratoire, d'écorce d'agrumes et de marc du pomme. Les résultats montrent une forte influence de la matière première sur la pectine résultante et ses propriétés rhéologiques. Les caractéristiques moléculaires ont été affectées négativement quand les farines des écorces ont été soumises à de hautes températures. Des farines blanchies des fruits de la passion jaune donnent des rendements de pectine de 203,4 g kg-1 avec une teneur en acide galacturonique de 681 mg g-1, des degrés d'estérification et de méthylation de 80, une viscosité réduite de 6,8 dL g-1 et une viscosité apparente de 13,4 Pa s 103 pour une solution aqueuse à 10 g L-1. L'autoclavage et la macération avec éthanol chaud ont conduit à une réduction significative de la masse molaire (environ de trois fois) et une légère réduction du degré d'estérification (proche 20%). Des traitements thermiques sévères de matière première affectent donc la qualité de la pectine extraite. Par contre, l'absence de traitement thermique de la matière première favorise la dégradation de la pectine, par la présence d'activités pectolytiques résiduelles, mises en évidence par une libération de méthanol dans un mésocarpe fraîche lyophilisé remis en suspension aqueuse. Un blanchiment de la matière première est donc indispensable. Dans les conditions d'extraction définies ci-dessus, la pectine de pomme a présenté le rendement d'extraction le plus faible mais le degré d'estérification le plus élevé, la viscosité et la masse molaire les plus fortes. La pectine extraite de farine de fruit de la passion jaune montre des caractéristiques proches de celles de la pectine de pomme, bien que légèrement plus faibles. Cette similitude est confirmée par une analyse en composantes principales, qui a permit la discrimination entre les pectines analysées, à partir des compositions en oses neutres. La pectine extraite avec de l'eau et à froid à partir de mésocarpe de fruit de la passion jaune a des compositions en oses et un degré d'estérifications semblables à celle extraite en milieu acide à chaud, mais une masse molaire et une viscosité plus faibles. Ultérieurement, un plan d'expérience centré composite de 23 a été utilisée pour déterminer l'effet des variables indépendantes, continues et opérantes que sont la durée, la température et la concentration d'acide dans le processus d'extraction de pectine sur les variables dépendantes: rendement, degré d'estérification, teneurs et composition osidique des polysaccharides, ainsi que leur comportement rhéologique, afin de maximiser la qualité de la pectine. Les variables indépendantes étaient la durée (5-45 min), la température (63-97 ºC) et la concentration d'acide nitrique (8-92 mM). Le rendement de l'extraction et la viscosité apparent en solution saline ont été influencés significativement (> 5%) dans les essais. Les conditions idéales pour l'extraction de pectine avec la plus haute viscosité apparente et contenant les polysaccharides présentant un profil de masse molaire élevée ont été une duréecourte (5 min), une température moyenne (80 ºC) et une concentration moyenne d'acide nitrique (50 mM). Dans ces conditions, le rendement a été de 196 g kg-1 d'une pectine hautement méthylée avec une masse molaire apparent de 166.000 g mol-1, 78% d'acide galacturonique et 43 mg g-1 de sucres neutres. Néanmoins, cette pectine ne donnait pas un gel plus ferme (70% de saccharose, teneur en pectine 30 g L-1 dans un tampon citrate pH 3) que les autres échantillons analysés. Des échantillons des pectines avec des degrés d'estérification proches ont présenté des caractéristiques rhéologiques et des profils moléculaires différents. Les conditions d'extraction plus douces ont permis l'extraction de pectine des chaînes avec masse molaire plus élevée et en conséquence une viscosité plus élevée. Pour une utilisation industrielle du mésocarpe, le processus de séparation devrait inclure des opérations supplémentaires, en augmentant à la fois le coût et la durée du procédé. Cependant, étant donnée la haute valeur économique ajoutée de la pectine extraite, un traitement approprié du résidu pour l'obtention de matière première de qualité paraît primordial. Dans la mesure où il semble que le mésocarpe doive être préféré pour l'obtention d'une pectine avec une pureté et une viscosité élevées, cette fraction a été sélectionnée comme matière première pour suivre les études. Les écorces de fruit de la passion jaune, un résidu industriel du traitement de jus, peuvent constituer une matière première alternative pour extraction de pectine de haute qualité et ou une utilisation comme ingrédient fonctionnel naturel
354

The agricultural geography of the pear industry in Jackson County, Oregon

Goodman, Duane William 14 May 1963 (has links)
Jackson County, Oregon is noted for the production of high quality pears. It is the fourth leading pear producing county in the United States and is the number one producer of winter pears. This thesis analyzes in detail the many aspects of the pear industry in the county. Climate, soils, topography, and progressive growers have been the main localizing factors. The study revealed that 200 growers produce the average annual total of three million boxes of pears on 9940 acres of bearing orchards. The pears are prepared for market in 12 packing houses and two canneries. The industry has a direct impact on the county of $15,000,000. The problems confronting the industry are caused by physical and biological factors. Spring frosts and hail damage are problems imposed by the climate. Pear Blight, Pear Decline, and Pear Scab are the main diseases. Insect pests such as the Pear Psylla and the Codling Moth must also be combatted. Urban encroachment has not yet been a serious problem in the county. The future for the industry appears to be stable, with little change in acreage. The fruit gift box industry will become of increasing importance, thus creating further emphasis on producing winter pears. / Graduation date: 1963
355

Enhancing the Expression of Enzymes Used to Degrade Hydrocarbons and Cyanohydrins in Rhodococcus sp. DAP 96253 by Using Inducers such as Cobalt, Urea, and Propylene Gas; Also Enhances the Ability of the Bacteria to Delay the Ripening of Several Fruit Species

Perry, Guenevere Diane 14 December 2011 (has links)
ABSTRACT Recent studies have shown that R. rhodochrous DAP 96253 has the ability to delay the ripening of many climacteric fruit, by potentially degrading volatile compounds released by plant cells during the ripening process. Rhodococcus rhodochrous DAP 96253 cells were cultured on YEMEA medium supplemented with inducers, (16mM cobalt and 125mM urea), that over-expressed nitrile hydratase (NHase) and amidase (AMDase) enzymes. Cells were cultured on propylene/ ethylene as sole carbon source to induce alkene monooxygenase (AMO) like activity. Induced R. rhodochrous DAP 96253 cells displayed an 83% increase in final total dry weight compared to cells previously cultured on non-induced medium. Induced R. rhodochrous DAP 96253 cells displayed a 53-85% increase in NHase activity after exposure to propylene/ethylene, and cells displayed a 24-53% increase in NHase activity after exposure to fruit. Non-induced R. rhodochrous DAP 96253 cells displayed a 1-5% increase in NHase activity after propylene/ethylene, and cells displayed an 18-38% increase in NHase activity after exposure to fruit. Propylene/ethylene induced nitrilase activity in non-induced R. rhodochrous DAP 96253cells. Experimental results suggest that R. rhodochrous DAP 96253 may use NHase, amidase, nitrilase, and AMO like activity to delay ripening of climacteric fruit. Rhodococcus rhodochrous 96253 cells cultured on propylene/ethylene and cofactors (16mM cobalt and 125mM urea) displayed improved ability to delay ripening of fruit.
356

Profil phénologique et caractérisation biochimique des fruits du sureau du Canada (Sambucus canadensis L.)

Mathieu, Fannie January 2009 (has links) (PDF)
Les fruits du sureau du Canada (Sambucus canadensis L.) possèdent un bon potentiel pour les marchés alimentaires et nutraceutiques. Cependant, peu d'études ont porté sur ces fruits qui auraient besoin d'être caractérisés. Le premier volet de ce projet visait à évaluer la teneur en sucres solubles (SS), en anthocyanes (ACY), en composés phénoliques totaux (CPT) ainsi que la capacité antioxydante (CA) des fruits de cinq cultivars et de l'espèce indigène. Il a été montré que la composition des fruits variait selon le cultivar, le moment de récolte et l'année de croissance. Les cultivars Victoria et Scotia sont les cultivars contenant le plus de SS (16,8 et 16,5 °Brix, respectivement). Les cultivars qui contiennent la plus grande teneur en ACY, en CPT et la plus grande CA sont Nova (771 mg C3G/100 g MF; 1054 mg EAG/100 g MF; 60 µmol ET/g MF, respectivement) et Kent (755 mg C3G/100 g MF; 1015 mg EAG/100 g MF; 55 µmol ET/g MF, respectivement). Après comparaison de nos résultats avec ceux de la littérature, nous avons constaté que les fruits du sureau du Canada contiennent plus de ces composés que d'autres petits fruits habituellement qualifiés de riches en ces derniers. Il a également été observé que tous les cultivars n'atteignaient pas leurs teneurs maximales au même moment. Dans le but d'expliquer cette différence, un suivi du développement des fruits a été effectué. Pour y parvenir, nous avons mis au point une échelle basée sur la coloration des fruits. Par la suite, un parallèle avec les teneurs en SS, en ACY, en CPT et avec la CA a été effectué. Il s'avère que ces paramètres sont tous reliés à l'évolution de la coloration des fruits. De plus, la maturation des fruits variait selon le cultivar et l'année. Les cultivars étudiés présentent un avantage car leur temps de maturation est plus stable d'une année à l'autre (entre 60 et 68 jours) comparativement à celui de l'espèce indigène (64 jours en 2007 et 76 jours en 2006). Finalement, nous avons déterminé que l'utilisation conjointe de la teneur en SS et du suivi visuel de la coloration des fruits constituait un bon moyen d'évaluer le meilleur moment de récolte. Les résultats présentés fournissent, pour la première fois, des informations susceptibles d'orienter les industries alimentaires et nutraceutiques et de permettre aux producteurs de mieux gérer leur récolte. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Sureau du Canada, Anthocyanes, Composés phénoliques, Capacité antioxydante, Développement des fruits, Petits fruits.
357

Outcomes of the 2008 Georgia Senior Farmers' Market Nutrition Program

Ledford, Laurie 14 September 2009 (has links)
Background: The Georgia Senior Farmers’ Market Nutrition Program (GSFMNP) is intended to increase consumption of fruits and vegetables among Georgia’s low-income, older adults. The program provides $20 in vouchers with which participants may purchase Georgia-grown fruits and vegetables at approved farmers’ markets. Similar programs operate in other states, and studies suggest that these programs are successful in increasing fruit and vegetable intake among participants. However, because Georgia’s program operates somewhat differently, offering only a single market event at most locations, it may have different results. The purpose of this study was to determine whether or not produce purchased at GSFMNP events in 2008 contributed to an increase in the fruit and vegetable intakes of the participants and to identify factors that may have influenced those intakes. The study focused on purchase, consumption, preservation, waste, and sharing of fresh fruits and vegetables. Methods: For this qualitative study, a sample of 198 GSFMNP participants was surveyed from ten metro Atlanta senior centers where markets were held in August and September of 2008. Descriptive statistics were produced to summarize purchase behaviors, food utilization behaviors, and attitudes. Analyses of relationships between variables were performed using Pearson chi-square tests. Results: Twenty-seven percent of subjects reported consuming more fruits and vegetables than usual in the week following the farmers’ market event. There was a significant association between a larger than usual purchase amount and increased intake. There was also a significant association between increased intake and sharing purchased items. No significant associations with increased intake were found for variety of items purchased, preserving food, or discarding food. Those who purchased more fresh produce than usual appeared to be more likely to share their food with others but were not more likely to discard food. Ninety-seven percent of subjects said they would participate in the program again. Conclusion: Results of this study suggest that the majority of GSFMNP participants did not increase their intakes of fruits and vegetables. Sharing, preserving, and discarding food did not appear to be responsible for this outcome. More research is needed to discover what strategies could increase fruit and vegetable intakes among participants of the GSFMNP.
358

Apples abound farmers, orchards, and the cultural landscapes of agrarian reform, 1820-1860 /

Henris, John Robert. January 2009 (has links)
Dissertation (Ph. D.)--University of Akron, Dept. of History, 2009. / "May, 2009." Title from electronic dissertation title page (viewed 11/27/2009) Advisor, Kevin Kern; Committee members, Lesley J. Gordon, Kim M. Gruenwald, Elizabeth Mancke, Randy Mitchell, Gregory Wilson; Department Chair, Michael M. Sheng; Dean of the College, Chand Midha; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
359

Spray drying of fruit juice with vegetable fibre as a carrier : a thesis presented in fulfilment of the requirements of the degree of Doctor of Philosophy in Chemical and Process Engineering at the University of Canterbury /

Cheuyglintase, Kloyjai. January 1900 (has links)
Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). "January 2009." Includes bibliographical references (p. 215-236). Also available via the World Wide Web.
360

An Analysis of Consumption and Purchasing toward Organic Fruits : Cross-Countries Study between China and France

Fang, Zhengyangzi, Levy, Eliette January 2015 (has links)
Background: Organic food became a popular topic in recent years. Even though organic markets are becoming larger than before, the organic fruit market is still a niche market around the world. Consumers’ purchasing intentions towards organic products are impacted by many factors. Purpose: The purpose of this research study is to investigate the customers’ purchasing behaviors with different food-related lifestyles in China and France. Method: A research model and four hypotheses alongside the study have been used after reviewing relevant literatures. An online questionnaire survey was conducted in China and France, which resulted in 261 completed and usable responses. Results: All hypotheses were accepted representing all the independent variables, which includes attitudes toward purchasing organic fruit, subjective norms, perceived control and food-related lifestyles, influencing purchase intentions. In terms of research questions, the results suggested that food-related lifestyles in different countries exhibited positive significant relationships with customers’ planned behavior.

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