Aqueous two-phase systems formed by maltodextrin and acetonitrile: Phase diagrams and partitioning studies

Novel aqueous two-phase systems (ATPS) formed by water, acetonitrile and maltodextrin with different dextrose equivalent values (DE) are here described and characterized. The respective ternary phase diagrams were determined at 298.15 K. It was found that ATPS formed by maltodextrin and acetonitrile require lower amounts of phase forming-components to undergo liquid-liquid demixing than similar systems formed by mono- and disaccharides. To evaluate the ability of these systems as extraction strategies, experiments with vanillin were carried out. Conditions such as DE and concentration of maltodextrin, concentration of acetonitrile, and temperature were evaluated. In all the investigated systems, vanillin partitions preferentially to the top phase - acetonitrile-rich phase - with a partition coefficient (Kvan) ≫ 1. The best conditions for vanillin partitioning to this phase were obtained using maltodextrin DE 16.5-19.5 at 35 wt% + acetonitrile at 35 wt% + water at 30 wt%, at 308.15 K, for which Kvan and recovery in top phase (RT) was 12.4 and 91.8 %, respectively. The temperature has no statistical influence in the vanillin partitioning. According to the data gathered at different temperatures, it was found that the vanillin partitioning process is spontaneous, endothermic and governed by entropic forces. Finally, the density and viscosity of the studied aqueous two-phase system (ATPS) coexisting phases were determined, showing significant differences in viscosity and density between the phases, which is highly beneficial for phase separation and scaled-up applications.