1185Effects of XG/LBG gel concentration on the stability and rheological properties of G/O/G emulsions

Mi-Jung Choi1*, Jiseon Lee1, Si Yeon Kim2**

1School of Animal & Food Sciences and Marketing, Konkuk University, Korea
2Department of Food Science and Biotechnology of Animal Resources, Konkuk University, Korea

This study investigated the effects of incorporating xanthan gum (XG) and locust bean gum (LBG) into the inner gel phase (G₁) on the physicochemical properties of gel-in-oil-in-gel (G₁/O/G₂) emulsions, while the outer gel phase (G₂) was kept constant at 0.5%. XG and LBG were combined at a 1:1 ratio to form the G₁ gel matrix, and their concentrations were adjusted to 0, 0.3, 0.5, and 1.0%. The resulting emulsions were evaluated by visual appearance, microscopic observation, confocal laser scanning microscopy (CLSM), particle size analysis, ζ-potential, encapsulation efficiency (EE), rheological characterization, and sensory evaluation. The visual appearance of the emulsions remained uniform with no visible phase separation. Microscopic observation revealed that increasing the inner-phase gum concentration led to finer and more uniformly distributed droplets. CLSM analysis showed that the 0.5% and 1.0% formulations maintained highly stable G₁ droplets, exhibiting insignificant coalescence and strong interfacial stabilization. Particle size analysis showed that the 0% XG/LBG sample had a mean droplet size of 8.80 ± 3.90 µm, whereas the 1.0% formulation exhibited a significantly smaller size of 4.90 ± 1.90 µm ( p < 0.05), with droplet size decreasing as the G₁ concentration increased. ζ-potential values appeared reduced in magnitude, due to the decreased electrophoretic mobility caused by the gelled outer phase (G₂) compared with conventional emulsions. Encapsulation efficiency analysis showed that the 0.5% formulation achieved the highest retention of the internal aqueous phase, exhibiting the greatest encapsulation efficiency among all samples at 98.2% ( p < 0.05). Rheological evaluation showed shear-thinning behavior, and G′ consistently exceeded G″, confirming gel-like characteristics. Higher gum levels strengthened the network, with 0.5% exhibiting the most balanced elasticity. Higher gum content enhanced viscoelastic stability, with the 0.5% and 1.0% formulations maintaining the highest G′ and G″ values across the frequency range, indicating the strongest network structure. The rheological increase in viscoelasticity and network strength corresponded with higher perceived thickness in sensory evaluation. Notably, bitterness intensity was reduced in the 0.5% formulation, which, among all samples, provided the best balance between structural integrity and consumer acceptability. Collectively, the results demonstrate that while increasing XG/LBG concentration enhances network strength and droplet stability, the 0.5% XG/LBG formulation provides the most favorable balance between viscoelasticity, interfacial stabilization, emulsification efficiency, and sensory quality. This gel concentration promotes efficient droplet disruption, enhances encapsulation performance, and ensures sustained structural coherence, thereby representing the optimal formulation level for achieving both physicochemical stability and consumer-preferred quality in G₁/O/G₂ emulsions.