Stability of curcumin in oil-in-water emulsions: Impact of emulsifier type and concentration on chemical degradation

This study examined the impact of emulsifier type on the formation and stability of curcumin-loaded oil-in-water emulsions: sodium caseinate; Tween 80; quillaja saponin; gum arabic. The effectiveness of these food-grade emulsifiers at forming emulsions by microfluidization was characterized in terms of their surface load, i.e., the mass of emulsifier per unit surface area. The surface loads decreased in the following order: gum arabic (55.3 mg/m2) > > saponins (2.0 mg/m2) > Tween 80 (1.6 mg/m2) > caseinate (1.5 mg/m2), which indicated that much more gum arabic was required to form emulsions than the other emulsifiers. Curcumin-loaded emulsions were then prepared under conditions where there was just enough emulsifier to cover the droplet surfaces (“critical”), and under conditions where there was an excess of emulsifier in the aqueous phase (“excess”). Initially, both critical and excess emulsions were physically stable and had similar appearances. In all emulsions, curcumin degradation during storage occurred more rapidly at pH 7 than at pH 3, and was faster at 55 °C than at 37 °C. The physical and chemical stability of the curcumin-loaded emulsions also depended on emulsifier type. After storage at 55 °C for 15 days, the extent of curcumin degradation decreased in the following order: saponins > > gum arabic ≈ casinate ≈ Tween 80. Moreover, droplet creaming was observed ...
Source: Food Research International - Category: Food Science Source Type: research