Improving encapsulation efficiency and stability of water-in-oil-in-water emulsions using a modified gum arabic (Acacia (sen) SUPER GUM™)

A matured gum arabic, (Acacia (sen) SUPER GUM™) was investigated as an emulsifier to aid in the stabilisation of water-in-oil-in-water (W/O/W) emulsions. Emulsions were characterised by phase separation, confocal microscopy, droplet sizing, and encapsulation efficiencies (EE). Initial results showed that some precipitates were observed when SUPER GUM™ was dissolved in a 0.1 M sodium phosphate buffer and this necessitated the preparation of emulsions in distilled water systems. Interestingly, the ionic environment had an effect on the emulsifying ability of the synthetic hydrophobic emulsifier, polyglycerol ester of polyricinoleic acid (PGPR). The concentration of PGPR could be reduced to 2 wt% in distilled water systems with an EE>90%, while in buffered systems, 4 wt% PGPR was required to maintain a similar EE. SUPER GUM™ was added as an emulsifier to replace sodium caseinate either in the internal or external aqueous phase of W/O/W emulsions over a range of concentrations. It was found that SUPER GUM™ destabilised the W/O/W emulsions prepared with low PGPR concentration when added to the internal aqueous phase. On the other hand, addition of 10 wt% SUPER GUM™ to the external aqueous phase allowed further reduction in the PGPR concentration to 0.5 wt% whilst an EE>90% was maintained. W/O/W emulsions formed with SUPER GUM™ were also found to be stable over a wide pH range, compared to W/O/W emulsions stabilised with sodium caseinate, and thus, may be suitable for applications over a wide range of pH values, as may occur during ingestion or incorporation into different food systems.