Microencapsulation of oil droplets using cold water fish gelatine/gum arabic complex coacervation by membrane emulsification

Food grade sunflower oil was microencapsulated using cold water fish gelatine (FG)–gum arabic (GA) complex coacervation in combination with a batch stirred cell or continuous pulsed flow membrane emulsification system. Oil droplets with a controllable median size of 40–240μm and a particle span as low as 0.46 were generated using a microengineered membrane with a pore size of 10μm and a pore spacing of 200μm at the shear stress of 1.3–24Pa. A biopolymer shell around the oil droplets was formed under room temperature conditions at pH2.7–4.5 and a total biopolymer concentration lower than 4% w/w using weight ratios of FG to GA from 40:60 to 80:20. The maximum coacervate yield was achieved at pH3.5 and a weight ratio of FG to GA of 50:50. The liquid biopolymer coating around the droplets was crosslinked with glutaraldehyde (GTA) to form a solid shell. A minimum concentration of GTA of 1.4M was necessary to promote the crosslinking reaction between FG and GTA and the optimal GTA concentration was 24M. The developed method allows a continuous production of complex coacervate microcapsules of controlled size, under mild shear stress conditions, using considerably less energy when compared to alternative gelatine types and production methods. •Highly uniform complex coacervate microcapsules were produced at room temperature.•Fish gelatin/gum arabic complex coacervate shell was cross-linked by glutaraldehyde.•Continuous pulsed flow membrane emulsification was successfully used for the scale up.