Encapsulation of curcumin within oil-in-water emulsions prepared by premix membrane emulsification: Impact of droplet size and carrier oil on the chemical stability of curcumin

Oil-in-water emulsions containing curcumin with different droplet sizes were produced by premix membrane emulsification with different carrier oils: tributyrin (short chain triglycerides, SCT), medium chain triglycerides (MCT) and corn oil (long chain triglycerides, LCT). The influence of carrier oil type and droplet size on the physical stability, chemical stability of curcumin and lipid oxidation stability of emulsions were investigated. Turbiscan results indicated that the physical stability of emulsions was related to both carrier oils and emulsion droplet sizes. The oil type and droplet size of emulsions stored at 25 °C showed limited effect on the stability of curcumin, but significantly affected the stability of curcumin at 55 °C. Chemical stability of curcumin decreased with the decrease of emulsion droplet sizes. For each droplet size emulsions, the stability of curcumin decreased in the order SCT > MCT > LCT. Moreover, the lipid oxidation in LCT-based emulsions resulted in lower zeta potential of droplets, which was independent of emulsion droplet sizes. The presence of curcumin improved the oxidative stability of emulsions.