Microencapsulation par coacervation complexe des protéines du lactosérum et de la gomme d’acacia

Abstract : This work deals with the study of linseed oil microencapsulation by complex coacervation of whey proteins and acacia gum. It focuses on the coacervation of whey proteins and acacia gum in aqueous medium as well as the mechanisms involved in the formation of microcapsules by complex coacervation. Complex coacervation is an associative phase separation phenomenon induced by electrostatic interactions between two polymers. The most widely used pair of polymers in complex coacervation is the system gelatin / acacia gum. However, the use of gelatin is a matter of controversy for food applications. An interesting alternative to gelatin consists of whey proteins and their major component, beta-lactoglobulin. An investigation of the composition of the coacervate system whey protein / acacia gum was carried out during this work. Capillary gel electrophoresis was used to quantify beta-lactoglobulin and alphalactalbumin in the coacervate. The influence of protein / polysaccharide ratio and pH on the composition of the coacervate was studied. Although the encapsulation process by complex coacervation has been known for many years, the mechanisms leading to the formation of microcapsules are not so much described. The encapsulation process by complex coacervation leading to the formation of microcapsules includes several stages that were examined. The emulsification step takes place in the intermediate flow regime. The modeling in turbulent regime accounted for experimental results and might be used for scaling-up the process. In situ monitoring of the encapsulation process by complex coacervation was performed for the first time in this study. It was carried out using a video probe immersed in a stirred reactor. This technique identified four successive steps induced by lowering the pH: the emulsification of the oil, the formation of the coacervate, the adsorption of the coacervate on the oil droplets, the formation of an encapsulation shell. The influence of physico-chemical parameters (protein / polysaccharide ratio and total concentration of biopolymers) and parameters related to the coacervation step on the formation of microcapsules were also studied by using the video probe
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Delphine Ach. Microencapsulation par coacervation complexe des protéines du lactosérum et de la gomme d’acacia. Génie chimique. Université Claude Bernard - Lyon I, 2014. Français. ⟨NNT : 2014LYO10186⟩. ⟨tel-01127432⟩

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