Preparation of monodisperse aqueous microspheres containing high concentration of l-ascorbic acid by microchannel emulsification

Abstract

Monodisperse aqueous microspheres containing high concentrations of l-ascorbic acid with different concentrations of sodium alginate (Na-ALG) and magnesium sulfate (MgSO₄) were prepared by using microchannel emulsification (MCE). The continuous phase was water-saturated decane containing a 5% (w/w) hydrophobic emulsifier. The flow rate of the continuous phase was maintained at 10 mL h⁻¹, whereas the pressure applied to the disperse phase was varied between 3 and 25 kPa. The disperse phase optimized for successfully generating aqueous microspheres included 2% (w/w) Na-ALG and 1% (w/w) MgSO₄. At a higher MgSO₄ concentration, the generated microspheres resulted in coalescence and subsequent bursting. At a lower MgSO₄ concentration, unstable and polydisperse microspheres were obtained. The aqueous microspheres generated from the MCs under optimized conditions had a mean particle diameter (d_av) of 14–16 µm and a coefficient of variation (CV) of less than 8% at the disperse phase pressures of 5–15 kPa.

• l-Ascorbic acid
• magnesium sulfate
• microencapsulation
• microchannel emulsification
• monodispersity
• sodium alginate

Declaration of interest

The authors report no declarations of interest. The authors alone are responsible for the content and writing of the article.