Impact of small molecule surfactant type and oil phase composition on Ostwald ripening in model food emulsions

Ostwald ripening destabilizes emulsified oils with significant water solubility, such as flavor oils, essential oils, and small triacylglycerols, by increasing oil droplet size over time. This study examined how small molecule surfactant types and oil phase composition affect Ostwald ripening rates in model oil-in-water emulsions. Emulsified n-decane was stabilized using two non-ionic surfactants with the different structures: polyoxyethylene (100) stearyl ether or poloxamer P407. The oil phase was varied by adding longer-chain alkanes (n-tetradecane, n-hexadecane, or n-octadecane) to the n-decane before homogenization. Although altering the oil phase composition did not change the oil–water interfacial tension, it significantly impacted initial droplet size and resistance to Ostwald ripening. Longer-chain alkanes reduced ripening rates due to a compositional ripening effect, with n-hexadecane being the most effective. Poloxamer-stabilized emulsions exhibited faster droplet growth than Brij-stabilized ones, due to differences in interfacial properties. These findings are crucial for inhibiting Ostwald ripening in various industrial emulsions.