Formulation and stability assessment of ergocalciferol loaded oil-in-water nanoemulsions: Insights of emulsifiers effect on stabilization mechanism

In the study, we investigated the effect of emulsifiers with different stabilizing mechanisms on the formulation and stability of ergocalciferol loaded oil-in-water (O/W) emulsions. O/W emulsion stabilized by modified lecithin (ML; electrostatic stabilization), sodium caseinate (SC; electrosteric stabilization) or decaglycerol monooleate (MO-7S; steric stabilization) were formulated using high-pressure homogenization. The Sauter mean diameter (d(3,2)) of emulsions produced by ML, SC and MO-7S were 126 +/- 1, 127 +/- 4 and 138 +/- 3 nm, respectively. The stability of resulting emulsions was evaluated when they exposed to different environmental stresses and during 30 days of storage at 25 and 55 degrees C. Results showed that the emulsions prepared by MO-7S or ML were stable against a wide range of pH (2-8), while SC-stabilized emulsions showed instability with extensive droplet aggregation at pH 4 or and 5. Only ML-stabilized emulsions showed droplet growth due to coalescence when treated at high NaCl concentration (300-500 mM). In the absence of glucose, SC-stabilized O/W emulsions showed better freeze-thaw stability, in comparison to those formed with ML or MO-75 emulsifiers. The emulsion produced by ML was found to be stable to droplet aggregation at heating temperatures (80-120 degrees C) for 1 h. All the O/W emulsions stored at 25 degrees C showed good physical and chemical stability. However, the chemical stability of ergocalciferol in emulsion system decreased in order of ML > MO-7S >> SC during storage at 55 degrees C for a period of 30 days. These findings provide valuable information for the development of nanoemulsion-based delivery system applied in food and beverage products. (C) 2016 Published by Elsevier Ltd.