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This thesis investigates the impact of the addition of long chain triglycerides (LC-TAGs) on the 
behaviour of coconut oil (CO) during its dry fractionation. The main objective of this improved dry 
fractionation process is different from the usual stearin use. Indeed, the goal is to increase the content of medium chain triglycerides (MCT content - C6 to C10) in the oleic fraction recovered after vacuum filtration. Two vegetable oils were used to provide LC-TAGs (Vegetable oil 1 and 2). These were chosen due to their high content of LC-TAGs. The crystallization was examined during the main crystallization and during the post-cooling. The effect of long chain triglycerides on the CO crystallization: solid fat content (SFC) increase, polymorphism, morphology of the crystals and viscosity of the slurry using scanning calorimetry, pulsed-nuclear magnetic resonance, powder X-ray diffraction, microscopy and viscosimeter. The addition of vegetable oil 2 would appear to be more advantageous compared to the addition of vegetable oil 1. Indeed, the SFC in the mixture and the content of medium chain triglycerides in the olein fraction increased more (up to 9.5% SFC and 14,7% MCT content) while limiting the increase of the viscosity in the medium below 3500 cP. In addition, the induction time for crystallization is also improved, being reduced to 2 hours instead of 7 hours, as was the case with CO alone or CO+vegetable oil 1. The β'-polymorphism of CO as well as the morphology of the crystals were not influenced by the addition of vegetable oil 2. This can be explained by a good match between CO and vegetable oil 2 triglycerides and their nucleation on each other's surface. This strong interaction is the result of a model effect, itself due to the matching chain lengths of the triglycerides present. Finally, it also appears that the temperature delta between water and oil and the duration of post-cooling influence the final amount of medium chain triglycerides in the oleins, regardless of the type of LC-TAGs added to CO.

Coconut oil, dry fractionation, improvement --- Ingénierie, informatique & technologie > Ingénierie chimique

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Plant communities --- Plant communities --- Community development --- Community development --- land improvement --- land improvement --- Landscaping --- Landscaping --- environmental protection --- environmental protection --- Belgium --- Belgium

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vegetation. --- vegetation --- Plant communities --- Plant communities --- pasture improvement --- pasture improvement --- Grazing --- Grazing --- Mediterranean zone --- Mediterranean zone --- North Africa --- North Africa --- Tunisia --- Tunisia

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socioeconomic organization --- socioeconomic organization --- agrosilvopastoral systems --- agrosilvopastoral systems --- Grazing --- Grazing --- Botanical composition --- Botanical composition --- pasture improvement --- pasture improvement --- animal husbandry methods --- animal husbandry methods --- Burkina Faso --- Burkina Faso

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In Morocco, pressure on rangelands has been increasing for the last two decades, threatening the balance of the pastoral system. This regressive trend stems from the extension of crops into rangelands and from the drop in forage production because of overgrazing. In order to find a compromise between the agricultural production and rangeland preservation, control and long- term planning are central. Farming practices will need to be changed drastically. The complexity of the problem is best met with a modelling approach, which takes into account the various interactions between the land user's decisions and the many technical, economic and environmental constraints. For optimal control, two dynamic models were constructed, based on the maximum principle method, and tested at national and regional levels. The optimal rangeland cropping control model, applied to the national and the Tadla region levels, reproduces the current technical and economic conditions involved in land allocation between the rival activities i. e. cropping and pastoralism. Optimal rangeland levels were determinated and variations were simulated according to changes in the economic policy. The stocking rate optimal control model was tested in two pastoral regions i. e Oriental and Middle Atlas, and was led to the definition of optimal forage resource management, mainly the optimal stocking rate and the equilibrium level for the forage stock. Moreover, the bio-economic approach has power to be of great interest in the evaluation of the economic and climatic parameters affecting the management process. Results of both models have led to some proposals forwards an economic environment favourable to the preservation of rangeland areas and the promotion of a rational forage resource management.

Sheep --- Sheep --- Goats --- Goats --- Grazing systems --- Grazing systems --- Rangelands --- Rangelands --- Environmental impact --- Environmental impact --- Stocking density --- Stocking density --- pasture improvement --- pasture improvement --- Models --- Models --- Morocco --- Morocco