Storage stability of food-grade bimodal oil-in-water emulsions: Effects of emulsifier type and combination

• Food Emulsion Blends (FEBs) are formed by mixing two monodisperse emulsions. • The storage stability of FEBs varied depending on the droplet size combination. • FEBs with 1 and 10 µm droplets retained size distributions after 30 days at 25 °C. • FEB stability was evaluated in terms of interfacial characteristics. • Using mixed emulsifiers further improved the storage stability of FEBs. The growing demand for personalized foods has increased the need for emulsion systems with precisely controllable physicochemical properties. This study investigated the storage stability of food emulsion blends (FEBs), which are bimodal oil-in-water emulsions prepared by mixing two monodisperse emulsions with different particle sizes and interfacial compositions. Soybean oil was used as the dispersed phase, and the continuous phase contained 1.0 % (w/w) polyoxyethylene (20) sorbitan monolaurate (Tween 20, TW), decaglycerol monolaurate (ML 750, ML), or a mixed emulsifier solution containing 0.5 % (w/w) of each. Monodisperse emulsions with particle sizes of 1, 10, and 50 μm were prepared using premix membrane emulsification and combined in equal volumes to produce FEBs. After storage at 25°C for 30 d, FEBs composed of 1 and 10 μm particles (TW₁,₁₀ and ML₁,₁₀) maintained distinct bimodal size distributions, whereas those containing 50 μm particles exhibited destabilization between Days 10 and 20. ML-stabilized FEBs showed greater stability, with ζ-potentials ranging from −46.5 to −53.6 mV, compared with −24.0 to −37.6 mV for the TW-stabilized FEBs. The molecular-occupied areas were 1.61 μmol/m² for ML and 1.82 μmol/m² for TW, indicating denser interfacial packing for the ML. These results highlight the importance of electrostatic repulsion and interfacial organization in enhancing FEB stability. Among the FEBs combining 10 and 50 μm particles, those stabilized with mixed emulsifiers exhibited the highest stability. Overall, this study provides insights into the interfacial design of FEBs with an improved shelf life and supports their application in sustainable and personalized emulsified foods.