Optimization of parameters affecting dealcoholization of anthocyanin extract by liquid emulsion membrane using response surface methodology

Colour is one of most important properties of foods and beverages and is a basis for their identification and acceptability. Anthocyanin from red cabbage was extracted using 50 % ethanol. The extract was dealcoholized by Liquid Emlusion Membrane technology (LEM). Parafin oil was used as a solvent, lecithin was used as a surfactant and water as stripping medium. Response surface methodology (RSM) was used to design the experiments. A total of 30 experiments were conducted in accordance with central composite rotatable design. Design expert 8 was used to design the experiments. % extraction of alcohol in each case was determined. A suitable model was fitted to experimental data by regression analysis (R-square=0.93). Response surface plot were analysed and optimum parameters for dealcoholization were found to be speed=365.44 rpm, time=18.62 min, concentration of lecithin=2.84 %, feed to emulsion ratio=3.05. A maximum dealcoholisation of 18.63 % was observed under these conditions

Vaporizable endoskeletal droplets via tunable interfacial melting transitions

Liquid emulsion droplet evaporation is of importance for various sensing and imaging applications. The liquid-to-gas phase transformation is typically triggered thermally or acoustically by low–boiling point liquids, or by inclusion of solid structures that pin the vapor/liquid contact line to facilitate heterogeneous nucleation. However, these approaches lack precise tunability in vaporization behavior. Here, we describe a previously unused approach to control vaporization behavior through an endoskeleton that can melt and blend into the liquid core to either enhance or disrupt cohesive intermolecular forces. This effect is demonstrated using perfluoropentane (C5F12) droplets encapsulating a fluorocarbon (FC) or hydrocarbon (HC) endoskeleton. FC skeletons inhibit vaporization, whereas HC skeletons trigger vaporization near the rotator melting transition. Our findings highlight the importance of skeletal interfacial mixing for initiating droplet vaporization. Tuning molecular interactions between the endoskeleton and droplet phase is generalizable for achieving emulsion or other secondary phase transitions, in emulsions.

Mobile-surface bubbles and droplets coalesce faster but bounce stronger

Enhancing the hydrodynamic interfacial mobility of bubbles and droplets in multiphase systems is expected to reduce the characteristic coalescence times and thereby affect the stability of gas or liquid emulsions that are of wide industrial and biological importance. However, by comparing the controlled collision of bubbles or water droplets with mobile or immobile liquid interfaces, in a pure fluorocarbon liquid, we demonstrate that collisions involving mobile surfaces result in a significantly stronger series of rebounds before the rapid coalescence event. The stronger rebound is explained by the lower viscous dissipation during collisions involving mobile surfaces. We present direct numerical simulations to confirm that the observed rebound is enhanced with increased surface mobility. These observations require a reassessment of the role of surface mobility for controlling the dynamic stability of gas or liquid emulsion systems relevant to a wide range of processes, from microfluidics and pharmaceuticals to food and crude oil processing.