A series of experiments were conducted to examine the effect of petroselinic acid, found in coriander oil, on fillet, hepatocyte and whole body FA composition and Δ6 desaturase gene expression in hepatocytes of rainbow trout (Oncorhynchus mykiss) fed vegetable oil (VO) based diets containing no fishmeal (FM) or fish oil (FO). In the first experiment, rainbow trout were fed one of eight diets containing fish, flax, canola or Camelina sativa oil with or without coriander oil. Coriander oil in the diet increased concentrations of eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3, P < 0.05) in the fillet. There was a trend to increased 20:5n-3 + 22:6n-3/20:4n-6 ratios when coriander oil was added to the diet (P = 0.067). The second trial set out to investigate the effects of varied levels of coriander oil in canola oil based diets, on i) the capacity of rainbow trout hepatocytes to desaturate, elongate and esterify [1-14C] α-linolenic acid (18:3n-3; ALA) and [1-14C] linoleic acid (18:2n-6, LA), ii) reducing the production of 20:4n-6 in hepatocytes and iii) gene expression. This experiment demonstrated a significant increase in 22:6n-3 (P = 0.011) and a decrease 20:4n-6 (P = 0.023) in rainbow trout hepatocytes. Furthermore, there was a three-fold decrease in acetate for the [1-14C] 18:2n-6 and nearly a two-fold increase for the [1-14C] 18:3n-3 substrate when coriander was added at increasing levels, illustrating an increase in peroxisomal β-oxidation. Relative gene expression of ∆6 desaturase decreased with addition of coriander oil at the 0.5 inclusion level of coriander oil. The final experiment was conducted to determine if bypassing the first ∆6 desaturase and rate-limiting step in the n-3 FA pathway causes increased conversion of stearidonic acid (SDA; 18:4n-3) to 20:5n-3 and 22:6n-3. Rainbow trout were fed one of six diets containing either fish, conventional linseed (flax), or SDA enriched linseed oil (LO) with and without coriander oil. Inclusion of coriander oil did not affect any growth or feed intake parameters of rainbow trout. However, the addition of coriander oil caused a significant increase in whole body 22:6n-3 and 20:4n-6 concentrations in fish fed SDA enriched LO with coriander oil (SDA+C) compared to fish fed conventional linseed oil (LO). These results suggest that petroselinic acid, found in coriander oil, has the ability to influence FA bioconversion of the n-3 and n-6 FA pathway thereby increasing 22:6n-3 and possibly 20:5n-3 in rainbow trout and reducing ARA when fed VO-based diets. Furthermore, it seems as though petroselinic acid causes improved bioconversion to 22:6n-3 when the first ∆6 desaturase is bypassed. Further studies are needed to determine the mechanism of action that petroselinic acid has on FA bioconversion.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Le biodiesel, provenant de sources renouvelables, devient de plus en plus intéressant pour des raisons environnementales et à cause de la perspective de la pénurie des carburants fossiles. La méthode principale pour la production de biodiesel est la réaction de transestérification de l'huile végétale catalysée par des catalyseurs acides, basiques ou enzymatiques en phase homogène ou hétérogène. Le but de ce travail est d'étudier une nouvelle voie de production de biodiesel à partir de l'huile de colza en utilisant un liquide ionique comme catalyseur et le CO2 supercritique comme milieu réactionnel. Les liquides ioniques fonctionnalisés sulfoniques sont des liquides ioniques acides possédant de bonnes propriétés catalytiques pour la transestérification de l'huile. Le caractère lipophile du liquide ionique ainsi que l'alcool influence la performance de la réaction. L'éthanol et le 1-propanol sont plus réactifs que le méthanol à cause de leur meilleure solubilité dans l'huile. Le liquide ionique peut être recyclé et la séparation des esters d'acides gras a lieu par simple décantation. L'effet du CO2 sur la transestérification de l'huile de colza catalysée par les liquides ioniques n'est pas clairement positif à cause de l'extraction préférentielle de l'éthanol. Cependant, en rajoutant l'éthanol en continu, l'influence du CO2 devrait être plus favorable. Le CO2 pourra être également utilisé en fin de réaction comme solvant permettant de séparer des esters, du glycérol et du catalyseur. / Biodiesel, resulting from renewable sources, becomes more and more interesting for environmental reasons and because of the perspective of the shortage of fossil fuels. The main method for the production of biodiesel is the reaction of transesterification of vegetable oil catalyzed by acid, basic or enzymatic catalysts in homogeneous or heterogeneous phase. The purpose of this work is to study a new way of biodiesel production from the rapeseed oil by using an ionic liquid as catalyst and supercritical CO2 as reaction media. The HSO3 functionalized ionic liquids are acid ionic liquid possessing good catalytic properties for the oil transestefication. The lipophilic character of ionic liquid as well as alcohol influences the performance of the reaction. Ethanol and 1-propanol are more reactive than methanol because of their best solubility in the oil. The ionic liquid can be recycled and the separation of the esters of fatty acids takes place by simple settling. The effect of CO2 on the transesterification of rapeseed oil catalyzed by ionic liquids is not clearly positive because of the preferential extraction of the ethanol. However, by adding the ethanol continuously, the influence of CO2 should be more favorable. Supercritical CO2 can be also used to separate esters, glycerol and catalyst at the end of reaction.

Thesis (M.S.)--Mississippi State University. David C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.