Comparative evaluation of corn, coconut, and coconut testa oils in sodium alginate-stabilized nanoemulsions processed by microfluidization

The limited stability of conventional emulsions has led to the development of sodium alginate-stabilised nanoemulsions, which offer enhanced functionality for food applications. This study aimed to formulate nanoemulsion stabilized by sodium alginate (0.5% w/v) and Tween 80 (1% v/v) using three types of oil (1% v/v): corn, coconut, and testa oil. The particle size of the emulsion was initially reduced by homogenizing a coarse emulsion (15000 rpm/ 5 min), followed by five passes through the microfluidizer. Changes in the physicochemical properties of the emulsions during microfluidization and over 24 days of storage were evaluated. The pH (5.2–6.2), and electrical conductivity (1090 − 1160 µS/cm) of the emulsions varied depending on the number of microfluidic passes, oil type, and storage duration. The third microfluidization pass produced significantly smaller nanoparticles (111.75 nm) with enhanced stability, exhibiting no signs of flocculation or creaming. Emulsions prepared with testa and coconut oils showed, lower zeta potential (–9.93 mV), higher whiteness index (59.547), viscosity (0.003859 Pa·s), and thixotropy of hysteresis loop area (9.742 Pa/s) compared to those prepared with corn oil. The emulsion containing testa oil and processed through the third microfluidization pass demonstrated the most favourable characteristics throughout the storage period. Overall, both the number of microfluidization passes and the type of oil significantly influenced the behaviour of sodium alginate-stabilized nanoemulsions.