Complex coacervation between proteins and polysaccharides for the encapsulation of active molecules ; Coacervation complexe entre protéines et polysaccharides pour l'encapsulation de molécules actives

Complex coacervation between oppositely charged proteins and polysaccharides has drawn a lot of attention during last decades, which has been widely applied for encapsulating bioactive molecules in food, pharmaceutical and agricultural fields. The first four studies of this thesis focused on the complex coacervation between a classic pair of protein and polysaccharide, sodium caseinate (CAS) and low methoxyl pectin (LMP). The complexation behavior and the effect of pH, ionic strength and temperature were studied through isothermal titration calorimetry (ITC) in the first study. Two strategies for preparing emulsions, (i) stabilization by CAS/LMP complexes formed in advance and (ii) stabilization by layer-by-layer (LBL) method were compared in the second work. In addition, the effects of shearing and heating during spray-drying on CAS/LMP complexes were investigated. Finally, an essential oil compound (citral) was encapsulated in an emulsion stabilized by CAS/LMP complexes, dry microcapsules were obtained through spray-drying in the presence of maltodextrins and their antimicrobial activity was evaluated. Besides complex coacervation between CAS and LMP, lysozyme (LYS) was complexed with CAS as heteroprotein complex coacervates, and CAS-LMP mixtures as ternary complexes at pH 7 in the last two studies. Overall, model bioactive compounds including hydrophobic (citral) and hydrophilic (LYS) molecules were successfully encapsulated through complex coacervation ; La coacervation complexe entre les protéines et les polysaccharides de charges opposées a attiré beaucoup d'attention au cours des dernières décennies, et a été largement appliquée pour l'encapsulation de molécules bioactives dans les domaines alimentaire, pharmaceutique et agricole. Les quatre premières études de cette thèse se sont concentrées sur la coacervation complexe entre deux biopolymères bien étudiés, le caséinate de sodium (CAS) et la pectine faiblement méthylée (LMP). Le déroulement de la complexation ainsi que l’effet du pH, de la force ionique ...