Preparation and characterization of palm oil emulsions stabilized by red ginseng saponin at varying concentrations: Effects of environmental factors on emulsion stability

This study investigates the potential application of red ginseng saponins as natural plant-based emulsifiers in palm oil emulsions. Emulsions were prepared with varying concentrations of red ginseng saponins (0.5% to 2.5%) and characterized in terms of particle size, particle size distribution, zeta potential, encapsulation efficiency, microstructure, and rheological properties. The results demonstrated that with increasing saponin concentration, the particle size initially decreased and subsequently increased, with the optimal concentration being 1.5%, which yielded the smallest droplet size (181.8 ± 3.3 nm) and highest encapsulation efficiency (99.54 ± 0.16%). All emulsions exhibited zeta potentials greater than 30 mV, indicating good electrostatic stability. Fluorescence microscopy confirmed that higher saponin concentrations contributed to more uniform oil droplet distribution. Rheological analysis revealed shear-thinning behavior, with smaller droplet sizes correlating with higher viscosity. The emulsions maintained conditionally dependent stability during storage and under thermal treatment; however, their stability was compromised under conditions of increased ionic strength and freeze-thaw cycling. These findings validate the potential of red ginseng saponins as effective natural emulsifiers for food applications, with further optimization needed to enhance stability under challenging environmental conditions.