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

Abstract

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.