Stability of Capsicum annuum oleoresin-in-water emulsions containing Prosopis and Acacia gums

Chilli oleoresin-in-water emulsions were stabilized with very low concentra tions of mesquite (Prosopis juliflora), arabic (Acacia senegal) and acacia (Acacia spp.) gums at different pH values in order to establish which polys accharide had the best emulsifying capacity and provided the best stability against droplet coalescence and pigment degradation. Mesquite gum was the best emulsifying and stabilizing agent, followed by gum arabic and acacia g um. In all cases, pH had a dramatic effect on the emulsion stability agains t droplet coalescence and color degradation. The stabilizing mechanisms gov erning these two deteriorative processes were opposite. While coalescence k inetics was hindered at high pH values, color degradation kinetics took pla ce at a higher rate, while the opposite effect occurred at lower pH values. A number of factors were important in determining the emulsifying capacity , the droplet coalescence stability and the color degradation stability of the gums among them, the protein content, the molecular weight, the surface charge and the steric configuration adopted at different pH values.