• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 46
  • 42
  • 8
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 127
  • 127
  • 35
  • 30
  • 16
  • 14
  • 13
  • 11
  • 11
  • 10
  • 10
  • 10
  • 9
  • 9
  • 8
  • 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.
81

Influence d’un régime riche en huile de palme sur le statut antioxydant, la fonction mitochondriale et les désordres métaboliques associés à l'obésité / Influence of a diet rich in palm oil on antioxidant status, mitochondrial function and metabolic disorders associated with obesity

Djohan, Youzan Ferdinand 10 November 2017 (has links)
L’huile de palme est l’huile végétale la plus consommée au monde. Du fait de sa teneur élevée en acides gras saturés (AGS), notamment en acide palmitique, cette huile est considérée par certains auteurs comme potentiellement nocive pour la santé. Cette étude avait pour objectif de comparer les effets de l’huile de palme (rouge ou oléine), à l’huile d’olive (réputée bonne pour la santé) et aux saindoux (riche en AGS), sur la santé. Pour réaliser cette étude, 40 rats mâles Wistar ont été répartis en 5 groupes de 8 rats chacun : 1 groupe contrôle et 4 groupes nourris par des régimes obésogènes contenant respectivement de l’huile de palme rouge, de l’oléine de palme, de l’huile d’olive ou du saindoux. Après 12 semaines de régime, les rats ont été sacrifiés et les tissus prélevés. Les examens réalisés sur les tissus ont montré que l’huile de palme (rouge ou oléine) induit un statut antioxydant et un profil lipidique superposables à ceux de l’huile d’olive. Tous les régimes obésogènes ont favorisé la prise de poids, l’altération de la fonction mitochondriale et la perturbation du métabolisme glucidique par l’induction d’une insulino-résistance. Il ressort de cette étude que l’huile d’olive est plus délétère pour le foie que l’huile de palme (rouge ou oléine) et le saindoux. Hormis l’huile de palme rouge, l’oléine de palme, l’huile d’olive et le saindoux influencent négativement les tissus adipeux. Les études menées sur l’aorte ont montré que les effets vasculaires de l’huile de palme sont moins délétères pour l’aorte que le saindoux et l’huile d’olive.Les résultats de cette étude indiquent que globalement, l’huile de palme (rouge ou oléine) n’a pas d’effets délétères supérieurs à ceux de l’huile d’olive concernant les organes qui ont été étudiés / Palm oil is the most consumed vegetable oil in the world. Because of its high content of saturated fatty acids (SFA), particularly palmitic acid, this oil is considered by some authors as potentially harmful to health. The aim of this study was to compare the effects of palm oil (red or olein), olive oil (considered good for health) and lard (rich in SFA), on health. To do this, 40 male Wistar rats were divided into 5 groups of 8 rats each: 1 control group et 4 groups fed by high fat diet (HFD) containing respectively red palm oil, palm olein, olive oil or lard. After 12 weeks of diet, the rats were sacrificed and the tissues removed. Tissue tests have shown that palm oil (red or olein) induces an antioxidant status and a lipid profile superimposed on those of olive oil. All HFD contributed to weight gain, impaired mitochondrial function, and disturbance of carbohydrate metabolism by the induction of insulin resistance. The study shows that olive oil is more deleterious to the liver than palm oil (red or olein) and lard. Apart from red palm oil, palm olein, olive oil and lard negatively influence adipose tissue. Studies on the aorta have shown that the vascular effects of palm oil are less deleterious to the aorta than lard and olive oil.Overall, the results of this study show that harmfull effects of palm oil (red or olein) were not worse than that of olive oil on organ that were analyzed
82

Le rôle des organisations de conservation dans la construction et la mise en œuvre de l'agenda international de conservation d'espèces emblématiques : le cas des orangs-outans de Sumatra / The role of conservation organizations in the construction and implementation of the international conservation agenda for emblematic species : the case of Sumatran orangutan

Ruysschaert, Denis 23 September 2013 (has links)
La thèse analyse le rôle des organisations de conservation dans la contradiction croissante entre, d’une part, la formalisation continue d’un cadre politique - juridique - institutionnel - financier - médiatique pour la conservation de l’orang-outang de Sumatra et, d’autre part, le constat avéré du déclin continu de son habitat et de ses populations. Partant du niveau global, elle se concentre ensuite dans le contexte indonésien, porteur d’un conflit aigu autour de la transformation de la forêt de basse altitude -habitat de l’orang-outan de Sumatra- en culture de palmier à huile.Le rôle des organisations de conservation sont étudiées à travers quatre dimensions sociologiques : l’établissement des référentiels globaux de conservation, la construction scientifique des indicateurs de référence, la mise en œuvre du droit indonésien et l’application de l’accord volontaire du RSPO.La thèse a trouvé des réponses concluantes pour chaque dimension et transversalement. Sans minimiser le rôle de l'état et du secteur privé, les ONG jouent aussi un rôle décisif dans le maintien du problème. Deux constantes sont observées : l'une est leur difficulté à tenir compte de la société qui abrite les populations d'orangs-outans, l'autre est leur propension à privilégier leurs propres intérêts afin de perdurer dans le champ social au détriment de leur objectif initial de conservation. Se préoccuper à ces deux manquements est le défi contemporain de la conservation. Des pistes sont donc données dans la conclusion pour refondre la gouvernance internationale de la conservation et pour redéfinir stratégiquement le rôle des ONG de conservation. Cette thèse est basée sur près de vingt ans d'expérience dans la gestion de l'environnement - à la fois pour des organisations de conservation et les Nations Unies - et 49 entretiens semi-directifs. / The thesis analyses the role of conservation organizations in the growing contradiction between, on the one hand a continuous and regular formalisation of a framework (political - legal - institutional - financial - media) for Sumatran orangutan conservation, and on the other hand, a proven report of the continuous decline of orangutan habitat and populations. Starting at the global level, the thesis then focuses on the Indonesian context that gives rise to an acute conflict centred on lowland primary tropical forest - the exclusive habitat of Sumatran orangutans - being converted into large-scale oil palm plantations. The role of conservation organizations has been studied through four sociological dimensions: i) the establishment of global paradigms for conservation, analysing in particular the Great Ape Survival Partnership - GRASP; ii) the "scientific" construction of reference indicators that characterise the orangutan; iii) the establishment and implementation of law at Indonesian level; and iv) the application of the voluntary agreement Roundtable on Sustainable Palm Oil - RSPO. The overall understanding of the role of NGOs is then given by the cross- analysis of the results under these four angles. The thesis has found articulated and conclusive answers for each dimension. Without underestimating the role of the state and the private sector, the cross-analysis shows that NGOs also play a decisive role in maintaining the problem of habitat loss and the decline of emblematic species, in particular the Sumatran orangutan. Two concomitant constants are observed. One is their difficulty to productively engage with the society that supports the wild orangutan populations. The other is their tendency to prioritize their own interests to perpetrate in the social and political sphere at the expense of their initial conservation objectives. To address these two structural shortcomings is the contemporary challenge for conservation. In the conclusion, suggested paths are given, both to reform international biodiversity governance and to strategically reorient the role of conservation organizations. The thesis is based on information gathered during twenty-years of experience in environmental protection - both in the United Nations and conservation organisations - and 49 semi-structured interviews.
83

Desacidificação por via física de óleo de palma = efeito da composição do óleo, das perdas de compostos nutracêuticos e cinéticas de degradação / Physical deacidification of palm oil : effect of oil composition, losses of nutraceutical compounds and reaction kinetics

Sampaio, Klicia Araujo, 1981- 18 August 2018 (has links)
Orientadores: Antonio José de Almeida Meirelles, Roberta Ceriani, Roland Verhé / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-18T16:00:03Z (GMT). No. of bitstreams: 1 Sampaio_KliciaAraujo_D.pdf: 2195076 bytes, checksum: 72dc0f10854796f82caf1148acc55ea8 (MD5) Previous issue date: 2011 / Resumo: Os parâmetros ótimos de desodorização (temperatura, porcentagem de vapor e pressão de operação) são determinados de acordo com o tipo de óleo e o processo de refino selecionado. O refino do óleo de palma é realizado preferencialmente através do refino físico, pois sua elevada acidez pode provocar uma perda excessiva de óleo neutro no caso da utilização do refino químico. O refino físico de óleos vegetais consiste num processo de esgotamento ou stripping, no qual sob pressões reduzidas e elevadas temperaturas os compostos voláteis são removidos do óleo neutro através da utilização de um agente de arraste, que pode ser um gás ou vapor. No entanto, estas condições de processo também facilitam a ocorrência de volatilização de valiosos compostos minoritários como esqualeno, tocoferóis, tocotrienóis, fitoesteróis, bem como uma pequena porção dos acilgliceróis. Desta forma, este trabalho apresenta a aplicação da metodologia de superfície de resposta (MSR) no estudo dos efeitos de três variáveis de processo (temperatura, porcentagem de vapor e fração estearina/oleína), sobre a perda/transferência de compostos graxos durante a desacidificação física. As respostas de interesse foram acidez final do óleo e perda de óleo neutro (PON). Os resultados revelaram que a composição do óleo é um fator importante e estatisticamente significante a ser considerado na seleção de variáveis de processo mais adequadas, além da temperatura e da porcentagem de vapor. Na segunda etapa, foi realizado um estudo detalhado da degradação térmica dos carotenóides no óleo de palma considerando-se temperaturas variando na faixa de 170 ºC a 230 ºC. O processo de aquecimento foi realizado com injeção de nitrogênio e a coleta de amostra foi feita a cada 20 min durante um período de aquecimento total de 140 min. Os dados experimentais foram então comparados com dados da literatura relacionados à degradação de carotenóides. A degradação térmica dos carotenóides mostrou uma melhor adequação a uma ordem de reação superior a 1. Em uma etapa posterior, a metodologia de superfície de resposta (MSR) foi aplicada para o refino físico de amostras de óleo de palma de diferentes qualidades, medidas através de sua acidez inicial. Foram consideradas a influência de duas condições de operação e um terceiro parâmetro de qualidade, sendo estes: temperatura, porcentagem de vapor e acidez inicial das amostras. As respostas de interesse foram acidez final do óleo, retenção de tocóis, perda de óleo neutro (PON) e retenção de carotenóides. Os resultados mostraram que a acidez inicial é um parâmetro estatisticamente importante para a obtenção de valores aceitáveis de acidez final. Este parâmetro está diretamente relacionado à concentração de componentes minoritários no óleo, pois caso o valor de acidez final não tenha atendido aos padrões pré-determinados, o óleo deve ser submetido a tratamentos subseqüentes utilizando-se temperaturas mais elevadas ou maiores tempo de processo, portanto, acarretando a redução dos compostos minoritários. Para finalizar este trabalho foi avaliada a ocorrência da reação de hidrólise de óleo neutro durante o processo de desacidificação física. Os resultados revelaram que as maiores concentrações de ácidos graxos livres (AGL) no óleo e as menores concentrações de AGL no destilado foram obtidas para as maiores vazões de vapor e menores tempos de processo. Observou-se também, que a geração de AGL aumenta com o aumento da porcentagem de vapor e da temperatura do processo. Através da análise da cinética da hidrólise de óleo neutro, foi possível verificar uma boa adequação dos dados à equação de primeira-ordem / Abstract: Optimal deodorizing parameters (temperature, steam percentage, and operating pressure) are determined by the type of oil and the selected refining process. Refining of palm oil is preferably performed by physical means since its high acidity can lead to excessive losses of neutral oil in case of the caustic refining process. Physical refining of vegetable oils is a stripping process in which, under low absolute pressure and high temperatures, the accompanying lower boiling compounds are distilled off from neutral oil, by using gas or steam, as effective stripping agent. However, these processing conditions also increase the occurrence of volatilization of the valuable minor components present in the oil such as squalene, tocopherols, phytosterols, as well as some portion of acylglycerols. Thus, this work presents the application of response surface methodology (RSM) to the study of the effects of three factors (temperature, percentage of stripping steam and the stearin/olein ratio) on the losses/transfer of fatty compounds during the steam deacidification. The responses of interest were the final oil acidity and the loss of neutral oil (NOL). The results revealed that the oil composition was an important and statistically significant factor in the selection of more suitable processing variables, besides temperature and steam. In the second step, a detailed study was performed for carotene thermal degradation in palm oil at four temperatures ranging from 170 ºC to 230 ºC. The heating process was carried out with injection of nitrogen and the samples were collected every 20 min during a total heating period of 140 min. The experimental data were then compared to literature data concerning carotenoids thermal degradation. The thermal degradation kinetics of carotenoids in palm oil followed an order superior to 1. In the next step of this work, response surface methodology (RSM) was applied to study the physical refining process of palm oil samples of different qualities, measured by their initial acidity. The influence of two operative conditions and a third quality parameter are considered: the temperature, the steam percentage, and the initial FFA. Their effect on the final FFA, tocols retention, neutral oil loss (NOL), and carotene retention was investigated. The results revealed that the initial FFA is a statistically important parameter to obtain acceptable values for final FFA, which has directly relation with the concentration of minor components in the oil by the submission to higher temperatures or longer refining periods, in order to reach the standard values. To end this work, it was evaluated the occurrence of hydrolysis of neutral oil during the steam deacidification. The results revealed that the highest percentages of FFA into the oil and the lowest percentages of FFA on the distillate were obtained when applying high steam flow rates associated with reduced stripping times. It was also observed that the generation of free fatty acids increases with the increasing of the percent of steam injected into the oil as well as with the increasing of the process temperature. The kinetic investigation revealed that the hydrolysis of neutral oil follows a first-order reaction / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos
84

Preservação dos componentes minoritários e desacidificação dos óleos de palma e farelo de arroz por resina aniônica forte / Preservation of minor components and deacidification of palm and rice bran oils using strong anionic resin

Cuevas, Maitê Sarria, 1983- 26 August 2018 (has links)
Orientadores: Antonio José de Almeida Meirelles, Christianne Elisabete da Costa Rodrigues / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-26T22:30:54Z (GMT). No. of bitstreams: 1 Cuevas_MaiteSarria_D.pdf: 2717993 bytes, checksum: 17efa4cb37bc6b620f40df08cfdf5c06 (MD5) Previous issue date: 2015 / Resumo: Os óleos de palma e farelo de arroz apresentam em sua composição carotenóides e gama-orizanol, respectivamente. Estes compostos minoritários representativos apresentam propriedades nutracêuticas, sendo desejável a sua preservação no óleo disponível para consumo. No entanto, as etapas de extração e refino de óleos vegetais apresentam grande impacto na perda ou preservação dos componentes minoritários. O objetivo desta tese foi priorizar a preservação dos componentes nutracêuticos nos óleos de farelo de arroz e de palma desacidificados por resina aniônica forte. Para atingir tal objetivo, inicialmente realizaram-se estudos de solubilidade do gama-orizanol, sendo desenvolvida uma metodologia para determinação da composição em esteril ferulatos em UPLC-MS, possibilitando a obtenção de dados de solubilidade dos esteril ferulatos que compõem o gama-orizanol. Os dados de solubilidade foram obtidos utilizando três solventes (hexano, n-propanol e metiletilcetona) a 30 e 50 ºC. Os resultados mostraram que tanto a temperatura, quanto o tipo de solvente influenciaram a composição de esteril ferulatos do gama-orizanol após o estabelecimento do equilíbrio de fases. Em adição, a solubilidade do gama-orizanol em misturas de solventes hexano:hexanol com diferentes composições (1:2; 2:1; 1:3 e 3:1) também foi estudada, sendo maximizada a solubilidade nas misturas contendo maior teor de hexanol. Os ensaios de solubilidade permitiram selecionar o solvente n-propanol para ser utilizado na etapa de desacidificação, uma vez que este apresenta solubilidade do gama-orizanol superior quando comparada ao hexano, além de permitir uma fácil remoção após o processo, por ser um solvente alcóolico puro com cadeia carbônica curta. Este mesmo solvente foi posteriormente utilizado na desacidificação do óleo de palma branqueado. A desacidificação de óleos vegetais por resina aniônica forte (Amberlyst A26 OH) permite a utilização de condições brandas de temperatura. Para aplicação desta técnica, inicialmente foram obtidas isotermas de adsorção de ácidos graxos em soluções de n-propanol e resina. Os resultados mostraram maiores concentrações de ácido na resina preferencialmente com o ácido oleico, seguido dos ácidos linoleico e palmítico. Para avaliar o processo de desacidificação foram obtidas curvas de ruptura de óleo de palma branqueado ou óleo de farelo de arroz degomado + n-propanol + resina aniônica forte. Os óleos desacidificados mostraram redução de pelo menos 91 % da acidez livre e preservação de seus componentes nutracêuticos: gama-orizanol (83 %), carotenóides (95 %), tocoferóis e tocotrienóis (100%), indicando que o processo de desacidificação proposto apresenta potencial para substituição dos processos convencionais, sendo possível a preservação dos componentes minoritários. Todavia, é necessário o estudo aprofundado da formação de ésteres durante o processo, como forma de avaliar o impacto na qualidade do óleo obtido / Abstract: The palm and rice bran oils present in its composition carotenoids and gamma-oryzanol, respectively. These representative minor compounds have nutraceutical properties, being important to preserve them in the oil available for consumption. The steps of extraction and refining have a great impact on the loss or preservation of minor components. The objective of this thesis was to prioritize the preservation of nutraceutical components in rice bran and palm oils deacidified by strong anionic resin. To achieve this goal, gamma-oryzanol solubility studies were performed, being developed an UPLC-MS methodology for the determination of steryl ferulates composition, which allow obtain solubility of gamma-oryzanol steryl ferulates. The solubility data were obtained using three solvents (hexane, n-propanol and methyl ethyl ketone) at 30 and 50 ° C. The results showed that both the temperature and the type of solvent influenced the gamma-oryzanol steryl ferulates composition after the establishment of the equilibrium phases. In addition, gamma-oryzanol solubility in mixtures of solvents hexane:hexanol with different compositions (1:2, 2:1, 1:3 and 3:1) was also studied. The solubility was maximized in mixtures containing higher levels of hexanol. Solubility tests allowed to select the n-propanol solvent for the deacidification step, since it presents greater solubility of gamma-oryzanol than hexane, and allow easy removal after the process, being an alcoholic pure solvent with short carbon chain. The same solvent was used in subsequent bleached palm oil deacidification. The deacidification of oils using strong anionic resin (Amberlyst A26 OH) allows the use of milder temperature conditions. For application of this technique adsorption isotherms of fatty acids in n-propanol and resin solutions were obtained. The results showed higher concentrations of the resin preferably with oleic acid, followed by linoleic and palmitic acids. To evaluate the process of deacidification breakthrough curves of bleached palm oil or degummed rice bran oil + n-propanol + strong anionic resin were obtained. The deacidified oils showed a reduction of at least 91% of the free acidity and preservation of their nutraceutical ingredients: gamma-oryzanol (83%), carotenoids (95%), tocopherols and tocotrienols (100%), indicating that the proposed deacidification process has potential to replace conventional processes, being possible the preservation of minor components. However, a deeper study of ester formation during the process is necessary, in order to assess the impact on the quality of the oil obtained / Doutorado / Engenharia de Alimentos / Doutora em Engenharia de Alimentos
85

Sustainability certification for deforestation-free supply chains: the cases of palm oil and soy

Hinkes, Cordula Verena Maria 25 March 2021 (has links)
No description available.
86

A more sustainable Palm oil industry : A case study on the Government in Indonesia achieving SDGs number 8 and 13 with the help of the palm oil industry

Pettersson Tobar, Rebecka January 2020 (has links)
In 2015, the United Nations adopted 17 sustainable development goals (SDGs) and 169 dub-goals, for all United Nations member countries. The goals are referred to as Agenda 2030 which aims to be guidelines for the countries as well as deepen the commitments of implementation.This paper aims to identify opportunities for how the palm oil industry can, through a more sustainable way, help to achieve objectives of UN ́s goals number eight and thirteen, by examining how the government in Indonesia works. Goal number eight: Decent work and economic growth, and goal number thirteen: Climate action.The analysis has been conducted through a qualitative case study based on scientific articles and various documents.The method used is A political economic approach together with an stakeholders analysis, where all stakeholders seek to be identified. The Government of Indonesia is working towards more sustainable production of palm oil and is undertaken by several stakeholders on the way, for example, the implementation of Indonesian Sustainable Palm oil (ISPO), which the government of Indonesia has installed to make the palm oil industry somehow contribute to meeting the SDGs.
87

Åt helvete med afrikanerna, låt dem dö!

Höst, Mariette, Prieto, Nicole January 2017 (has links)
Den negativa attityden kring palmolja har uppkommit för att industrin ur ett hållbarhetsperspektiv brister i sociala, ekonomiska och ekologiska aspekter. Produktionen finns i utvecklingsländerna, främst i Malaysia och Indonesien. Intresset för palmolja har ökat i Liberia, som tillsammans med Sverige är studieländer i den här undersökningen. Industrin har en stor miljöpåverkan, det förekommer dåliga arbetsförhållanden med låga löner och brist på rättigheter. Palmoljeindustrin har samtidigt i utvecklingsländerna gett möjlighet till ökad välfärd, då industrin är det som primärt ger inkomst för lokalbefolkningen.Studiens resultat visar att en uteslutning av palmolja i produkter inte är en lösning på problemet. En möjlig lösning till problemet är istället att samarbeta och jobba för hållbar odling av palmolja. / The negative attitude towards palm oil has arisen because of the sustainability of industry in social, economic and ecological aspects. Production is in developing countries, mainly in Malaysia and Indonesia. The interest in palm oil has increased in Liberia, which together with Sweden are study countries in this survey. The industry has a major environmental impact, there are poor working conditions with low wages and lack of rights. At the same time, in the developing countries, the palm oil industry has provided an opportunity for increased welfare, as the industry is the primary source of income for the local population.The study results show that an exclusion of palm oil in products is not a solution to the problem. A possible solution to the problem is instead to cooperate and work for sustainable cultivation of palm oil.
88

Effect of dietary lipid sources on the reproductive performance of Nile tilapia Oreochromis niloticus

Hajizadeh Kapateh, Ali January 2009 (has links)
Traditionally, fish oil (FO) has been used extensively in aquafeeds. The stagnation in global fish oil production coupled with an increased demand for its use in aquaculture feeds, especially salmonid feeds, has greatly inflated fish oil prices. Therefore, in order to sustain the rapid growth of the tilapia industry, the dependence on these commodities in feeds should be reduced through use of cheaper and more sustainable sources of dietary lipids, such as palm oil. This study therefore investigated several, previously poorly understood, effects of palm oil on reproductive performance of the commercial tilapia species, Oreochromis niloticus; which currently ranks as second most popular species in world aquaculture. In the present study broodstock were fed on experimental diets at full and half ration regimes throughout their entire life cycle from exogenous feeding. Studies were conducted in standardised and controlled hatchery conditions, thereby reducing the potential influence of environmental variations. First feeding O. niloticus fry were fed on four diets, cod liver oil (D 1), palm oil (D 2), mixed palm and cod liver oil (D 3) (9:1 ration) and a commercial trout diet as control (D 4) (Skretting, U.K.) on a reducing ration based on fish size. The present study investigated the effect of dietary lipid sources on (1) growth performance, (2) biochemical composition of eggs (total lipid and fatty acid composition), (3) morphological parameters of eggs (total and relative fecundity, egg size, egg weight and EW:BW), (4) larval quality (larval length and weight) and (5) oocyte recruitment and its associated sex steroid hormones. Experimental diets and feeding ration significantly influenced (p<0.05) the growth performance over a period of 120 days. Total lipid and fatty acid composition of eggs originating from broodstock fed on palm oil, mixed palm and cod liver oil (9:1) or a control diet were not significantly different (P>0.05) when fed at either full (3% BWday-1) or half ration (1.5% BWday-1). The present study, however, confirmed that fatty acid composition of fish eggs reflected the fatty acid composition of the diet, although specific fatty acids were selectively utilized or retained in the eggs. The mean inter-spawning interval (ISI) increased with increasing fish size and averaged 14, 19 and 24 days for fish fed on palm oil, mixed palm and cod liver oil or control diets, respectively. The shortest ISI observed was 7 days for fish fed a palm oil diet. Total fecundity ranged from 660 - 820 eggs/clutch. Mean total fecundity was 750, 820 and 660 eggs/clutch for fish fed a palm, mixed palm and cod liver oil or a control diet, respectively, but these differences were not significant (P>0.05). However, relative fecundity and egg weight to body weight rates as a percentage (EW: BW) were found significantly differ (p<0.05) between fish fed the control diet and experimental diets. Mean egg diameter (2.2 mm) was not significantly influenced (p>0.05) by experimental diets. The egg volume, egg dry and wet weight, fertilisation and hatching rate were also not significantly different between fish fed the experimental diets. Oocyte development was classified into distinct stages based upon oocyte size, biochemical properties and structure. The recrudescence to these stages was not significantly influenced by broodstock fed experimental diets either at full or half ration. Steroid hormones and histological analyses provided valuable data concerning the oocyte development and recruitment in this species. Levels of 17ß-oestradiol (E2) and testosterone (T) peaked within 6 days of spawning, suggesting that vitellogenesis began as early as day 2 or 3 post-spawning. By day 6, ovaries were dominated by large late-vitellogenic/maturing oocytes (stages 6 & 7) occupying about 70% of the ovary. Gonadosomatic index (GSI) reached maximal levels by day 6. It is suggested that pre-vitellogenic oocytes are recruited into vitellogenic growth immediately after spawning and complete vitellogenesis on day 6 post-spawning. Finally, the present study investigated the effect of food restriction at two rations (full and half) on broodstock reproductive performance. Oreochromis niloticus were rationed from first feeding and throughout their life-cycle. The dietary regime, full ration (3%) and half ration (1.5%), influenced fish size but despite this variation no significant differences (p>0.05) were detected in total lipid and fatty acid composition in the eggs, total fecundity, egg diameter, total egg volume and larval size. These results suggested that despite large differences in food availability throughout their life cycle, investment in reproduction had remained remarkably consistent. It appeared that during food restriction, O. niloticus sacrificed body weight and growth so as to maintain reproductive investment. In summary, this study provides valuable information using a novel experimental design on the effects of dietary lipid sources on reproductive performance of female O. niloticus. Substituting palm oil for fish oil as the dietary lipid source and reducing ration by half (1.5% BWday-1) had no significant effect on reproductive performance. Therefore it is suggested that under controlled conditions, lipids of non-marine origin, such as palm oil, can be successfully substituted for broodstock diets. Halving feed requirement should also increase profitability of seed production. KEYWORDS: Tilapia; O. niloticus; palm oil; diet; fecundity; spawning periodicity; oocyte recruitment; reproductive performance.
89

Optimisation des profils lipidiques du cerveau de rats déficients en oméga-3 au sevrage par l'utilisation de matière grasse laitière : conséquences au niveau du lipidome / Optimization of lipid profiles in the brain of rats deficient in omega-3 at weaning by the use of dairy-fat : consequence at the lipidomics level

Du, Qin 17 December 2010 (has links)
L‟acide docosahexaénoïque (DHA) s‟accumule principalement dans les membranes cérébrales humaines durant la période périnatale et les 2 premières années de la vie. Optimiser l‟incorporation des acides gras polyinsaturés à longue chaîne (AGPI-LC) n-3 dans le système nerveux central, notamment le DHA, constitue l‟un des objectifs majeurs de la nutrition néonatale et infantile. Ce projet étudie l‟effet de régimes à base de matière grasse laitière anhydre (MGLA) afin d‟améliorer la bioconversion des AGPI n-3 et l‟incorporation du DHA dans le cerveau. L‟autre objectif, au-delà des effets sur les acides gras, est d‟évaluer si l‟impact des apports destinés au jeune n‟exercent pas un effet plus large tels qu‟appréciés au niveau du lipidome du cerveau.Nous avons mis au point un modèle d‟expérimentation animale permettant d‟étudier les effets de mélanges de MGLA et d‟huiles végétales. Des mères sont nourries avec un régime déficient en acide α-linoléique (ALA) (0,4% des acides gras totaux (AGT)) pendant 6 semaines avant accouplement et pendant toute la gestation et la lactation. Après sevrage, quatre-vingts petits rats mâles et femelles ainsi carencés en AGPI n-3 sont séparés en 4 groupes et reçoivent des régimes à 10% de lipides pendant 6 semaines, soit à base d‟huile de palme mélangée avec des huiles vegétales pour un apport à 1,5%ALA (P1), ou 1,5% ALA supplementé avec 0,12%DHA et 0,4% acide arachidonique (ARA) (P2); soit à base de MGLA et d‟huiles végétales apportant 1,5%ALA (B1) ou 2,3%ALA (B2). Les acides gras cérébraux, plasmatiques et érythrocytaires ainsi que le profil lipidomique cérébral sont mesurés, et les résultats sont analysés en statistiques multivariées. Le régime B1 est supérieur aux deux régimes à base d‟huile de palme à 1,5 %ALA, pour restaurer la quantité de DHA du cerveau (augmentation de 14.38%, P < 0.05) ; le régime (B2) présente un bénéfice supplémentaire sur ce paramètre. Les concentrations cérébrales en DHA chez les rats mâles sont significativement plus faibles que chez les femelles en raison des interactions de l‟effet sexe sur l‟effet régime, mais cet effet s‟atténue avec les régimes MGLA ou l‟ajout de DHA préformés dans le régime palme (P2).Nous avons calculé un nouvel indice à l‟aide des profils en acides gras des globules rouges et du plasma pour prédire le contenu en DHA cérébral, et dont la performance est meilleure que celle des indices existants. Pour la première fois, nous avons pu mettre en évidence un effet majeur et inconnu jusqu‟alors, des régimes sur le lipidome du cerveau (analyse des espèces moléculaires de lipides), affectant près de 15% des espèces analysées. Ces changements semblent être liés, entre autres, au métabolisme du cholestérol, des acides gras et des messagers lipidiques.En conclusion, nos données sont susceptibles d„améliorer les formules infantiles. La première utilisation de l‟approche de lipidomique sans a priori que nous avons mise en oeuvre ouvre des perspectives nouvelles en nutrition infantile. / The accretion of docosahexaenoic acid (DHA) in brain membranes mainly occurs around delivery and during the first two years of life. One of the main goals of neonatal nutrition is to optimize the incorporation of n-3 long chain polyinsaturate fatty acids (LC-PUFA) into the central nervous system, including DHA. Our goal was to study the impact of several kinds of diets based on dairy-fat to improve the n-3 LC-PUFA bioconversion and DHA accretion into brain. The other endpoint was to assess if beyond the brain fatty acid profiles, the dietary intakes would bring about a wider effect such as the one that can be appreciated through a lipidomic approach.We compared the nutritional effect of dairy-fat based diets to that of palm-oil based diets in the rat reproductive model. Mother rats were made deficient in α-linoleic acid (ALA) (0.4% of fatty acids (FA) for 6 weeks prior to mating and throughout gestation and lactation. After weaning, the resulting deficient 40 rat pups of either gender were split into 4 groups and received 10% fat diets made with either 1.5%ALA palm oil blend (P1), same added with 0.12% DHA and 0.4% arachidonic acid (ARA) (P2) , 1.5% ALA dairy-fat blend (B1) or 2.5% ALA dairy-fat blend (B2). The brain, red blood cell (RBC) and plasma fatty acid profiles were analyzed and treated using multivariate statistics. B1 was superior to both palm-oil based diets to improve the brain DHA contents (14.4% increase, P < 0.05). B2 brought an additional benefit for this parameter. The brain DHA contents in males were significantly lower than for the female because of a diet x gender interaction. This effect was smoothed with the dairy-fat diets or the palm-oil based diet augmented with preformed DHA.We calculated a new fatty acid index to predict the brain DHA contents, based on the fatty acid profiles measured in RBC and plasma, and which demonstrated a better performance than the existing published index. For the first time, we showed a profound and yet unsuspected effect of diets until now on the brain lipidome (lipids molecular species), affecting about 15% of the features detected. These changes were ascribed to the cholesterol and fatty acid metabolism, and to the lipid messengers, among others.In conclusion, our data appear highly relevant to improve infant formulas. The first use of the lipidomic approach in neonatal nutrition open the paths of new researches in the area of infant nutrition
90

Huile de palme rouge au Burkina Faso: Qualité et consommation par les femmes de la zone de production et impact sur leur statut en vitamine A

Bougma, Karim 12 1900 (has links)
Dans le cadre de la recherche d’appui à la phase III du projet huile de palme rouge (HPR) au Burkina Faso, une étude de base a porté sur 150 femmes de la zone de production échantillonnées par la méthode aléatoire géographique. Leur statut en vitamine A (VA) a été évalué par HPLC et leurs apports alimentaires par un questionnaire de fréquence de consommation. Les connaissances, les perceptions, les habitudes d’utilisation et de consommation de l’HPR ont été explorées par un questionnaire pré-testé administré au domicile des participantes. Une étude comparative sur la qualité nutritionnelle, physico-chimique, microbiologique et sensorielle de 13 échantillons d’HPR de différentes provenances a été également réalisée. La prévalence de faibles rétinolémies était de 10,7% et les apports en VA provenaient à 90% des aliments d’origine végétale. Seules 5,9% des femmes productrices présentaient une faible rétinolémie, comparativement à 20,8% des femmes non-productrices d’HPR. Les échantillons d’HPR présentaient un profil satisfaisant mais quelques-uns étaient limites au plan microbiologique. En outre, aucun échantillon ne se distinguait nettement selon tous les paramètres de qualité étudiés. Cette étude démontre que les aliments d’origine végétale riches en caroténoïdes provitaminiques A, dont l’HPR qui en est la meilleure source, peuvent permettre d’avoir un statut adéquat en VA. Les risques de contamination de l’HPR au stade de la vente au détail impliquent une sensibilisation et une formation aux pratiques exemplaires de manipulation. Mots clés : Huile de palme rouge, vitamine A, diversification alimentaire, qualité, Burkina Faso. / The research activities of the phase III of the Red Palm Oil (RPO) project in Burkina Faso included a baseline study with 150 women of the RPO production area randomly selected by the Expanded Program on Immunization (EPI) random walk method. Their vitamin A (VA) status was assessed by HPLC and their dietary intake of VA by a food frequency questionnaire. The knowledge, perceptions, use and consumption patterns of RPO were assessed by individual interviews with a questionnaire. A comparative study on the physico-chemical, nutritional, microbiological and sensory quality of 13 RPO samples from different countries was also carried. The prevalence of low serum retinol was 10.7% and the dietary intake of VA was provided up to 90% by plant foods. Only 5.9% of women involved in RPO production presented a low retinol compared with 20.8% of women not producing RPO. The quality of the RPO samples was adequate although the microbiological counts were borderline for some samples. None of the samples presented an outstanding quality profile according to the criteria used. The study shows that provitamin A-rich plant foods, and RPO in particular as the highest source, can sustain an adequate VA status. The risk of contamination of RPO during retailing needs to be tackled through awareness and training in best manipulation practices. Key words: Red palm oil, vitamin A, food diversification, quality, Burkina Faso.

Page generated in 0.0912 seconds