Emulsifying and emulsion stabilization mechanism of pectin from Nicandra physaloides (Linn.) Gaertn seeds: Comparison with apple and citrus pectin

The emulsifying and emulsion stabilization mechanism of three kinds of pectin (Nicandra physaloides (Linn.) Gaertn seeds pectin-NP, apple pectin-AP, and citrus pectin-CP) were compared in terms of emulsions system, interface layer and pectin structure. The results showed the emulsifying properties of NP was superior to AP and CP, which attributed to lower interfacial tension (~15.57 mN/m) and better long-term stability to prepared emulsion. The long-term stability of NP emulsion ascribed to the higher emulsion viscosity, more uniform droplet size distribution, stronger electrostatic repulsion, and thicker interfacial layer. Structurally, the emulsifying activity of NP was mainly provided by acetyl and methyl groups, and the emulsifying stabilization was provided by the neutral monosaccharide side chains and ionized carboxyl groups. Therefore, the protein in pectin was not essential for the stabilization of oil-water interface, and the carbohydrate components played a crucial role in when especially lack of protein. Consider that the emulsifying properties of NP were independent of protein, it may be a potential natural emulsifier in resisting acid, ions, and heat.