Production of W/O/W emulsions and S/O/W pectin microcapsules by microchannel emulsification

Abstract

Water in oil in water (W/O/W) emulsions were produced by microchannel (MC) emulsification using water in oil (W/O) emulsions prepared by homogenization as feed emulsions. Polyoxyethylene sorbitan monolaurate (Tween 20) was used in the external water phase to stabilize oil droplets containing water droplets. Sorbitan monolaurate (Span 20), sorbitan monooleate (Span 80) and tetraglycerol polyricinoleate (TGPR) were tested as surfactants to stabilize the feed W/O emulsions. W/O/W emulsions were produced when using oleic acid or triolein as the oil phase and TGPR as the surfactant, while W/O/W emulsions could not be produced using Span 20 or Span 80 due to large water clusters and the low stability of the W/O emulsions. Using oleic acid as an oil phase, monodisperse W/O/W emulsions were obtained, while polydisperse W/O/W emulsions were produced using triolein as the oil phase, probably owing to the low production rate of the emulsion and fluctuation of the production rate. The concentration of TGPR affected the stability of the internal water droplets and oil droplets containing the water droplets. At a high TGPR concentration, the internal water was stable, however, oil droplets containing water droplets had a tendency to coalesce. W/O/W emulsions that contained pectin solution as an internal water phase were also produced using oleic acid and TGPR as the oil phase and surfactant in the oil phase, respectively. Solid in oil in water (S/O/W) pectin microcapsules were obtained by gelation of the internal water phase using a calcium solution containing Tween 20 as an external water phase.