Gum Arabic-stabilized conjugated linoleic acid emulsions: Emulsion properties in relation to interfacial adsorption behaviors

Abstract

Conjugated linoleic acid (CLA) is a dietary supplement due to its multiple health benefits. However, significant loss of biologically active CLA could occur due to oxidation. Oil-in-water emulsion is supposed to be an effective protection system. In a previous study (Yao et al., 2013), physical and chemical stabilities of CLA emulsion stabilized with gum Arabic were investigated, and the optimal gum concentration was identified as 5 wt%. The present study dealt with the interfacial adsorption of three gum Arabic samples (one conventional gum, GA; two matured gums, EM2 and EM10) at the CLA-water interface, in relation to their emulsifying properties. With increasing gum Arabic concentration, particle size (D[3,2]) of CLA emulsion decreased and slowly leveled off, which was accompanied with a gradual saturation of gum Arabic adsorbed at the emulsion interface. Nevertheless, surface load of gum Arabic at the emulsion interface (Γ, mg/m2) reached maximum at a gum concentration of 5 wt%. This could reasonably explain the optimal emulsion stability observed at this gum concentration, as revealed by particle size distribution of fresh emulsions and by acceleration test at 60 °C. Among the three gums, EM10 exhibited the highest emulsifying activity and conferred the best emulsion stability, despite of its lowest surface load. This is presumably due to a larger tendency of the AGP fraction in EM10 toward aggregation at the CLA-water interface.