Encapsulation of β-sitosterol plus γ-oryzanol in O/W emulsions: Formulation characteristics and stability evaluation with microchannel emulsification

Abstract

β-Sitosterol and γ-oryzanol have reduced solubility in aqueous based formulations. In this study β-sitosterol (β-st) and γ-oryzanol (γ-oz) were encapsulated at relatively high concentrations in different food-grade oil-in-water (O/W) emulsions using straight-through microchannel emulsification. The innovative aspect of this study was the production of monodisperse droplets with high encapsulation efficiency and stability of β-sitosterol and γ-oryzanol. Milli-Q water containing 1% (w/w) Tween 20 or decaglycerol monolaurate (ML-750) was used as the continuous phase and the dispersed phase contained 0.5–4% (w/w) each of β-st and γ-oz in medium chain triglycerides. Successful droplet generation was conducted with different concentrations of β-st and γ-oz. The Sauter mean diameter of 1% (w/w) β-st and γ-oz loaded O/W emulsions ranged between 26 and 28 μm with relative span factor width below 0.21. These emulsions were stable at 4 and 25 °C during evaluated storage period. The emulsions stabilized with Tween 20 have encapsulation efficiencies of β-st and γ-oz (EEβ-st and EEγ-oz) above 80% at 4 and 25 °C; those stabilized with ML-750 have EEβ-st over 80% and EEγ-oz above 50% at 4 and 25 °C.