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Molecular exchange processes in mixed oil-in-water nanoemulsions: Impact on droplet size and composition

Gao, Songran, Decker, Eric Andrew, McClements, David Julian
Journal of food engineering 2019 v.250 pp. 1-8
Ostwald ripening, differential scanning calorimetry, droplet size, droplets, hexadecane, hydrophobicity, ingredients, light scattering, mass transfer, mixing, nanoemulsions, oils, water solubility
The impact of oil water-solubility on mass transfer processes - Ostwald ripening (OR) and compositional ripening (CR) - in mixed oil-in-water nanoemulsions was investigated. Changes in droplet size distribution and composition were measured using dynamic light scattering and differential scanning calorimetry (DSC), respectively. Three nanoemulsions with similar droplet diameters (≈170 nm) were formed from oils with relatively low (octadecane), intermediate (hexadecane), or high (tetradecane) water-solubility. Mixed nanoemulsions were formed by blending these systems together (1:1). Complete oil exchange occurred within a few days for octadecane-hexadecane nanoemulsions and a few hours for tetradecane-hexadecane ones. For the latter system, rapid droplet growth (171–194 nm) occurred during the first 12 h due to CR, followed by slow droplet growth (194–204 nm) over the next 6.5 days due to OR. These results may be useful for optimizing the formulation of nanoemulsions containing multiple kinds of hydrophobic ingredient.