Emulsifying behaviour of gum arabic. Part 2: Effect of the gum molecular weight on the emulsion droplet-size distribution

The effect of the molecular weight of the gum arabic sample on droplet-size distributions of n-hexadecane-in-water emulsions (1% wt gum, 10% vol. oil) has been investigated at neutral pH. A high-molecular-weight fraction (0·87% nitrogen) corresponding to 10% of a natural gum (0·38% N) gives initially slightly larger droplets but better emulsion stability than the low-molecular-weight fraction (0·35% N) corresponding to the residual 90% of the original gum. Samples of a different gum arabic (0·35% N) subjected to different degrees of controlled degradation give decreasing emulsion stability with reduction in weight-average molecular weight from 3·1 × 10⁵ to 2·2 × 10⁵Da.