Efficacy of Curcumin–Surfactant Complex Towards Stabilisation of Emulsions

Emulsions stabilised by curcumin–surfactant mixture have received insufficient attention in the literature despite their wide-ranging applications in food, pharmaceutical and consumer industry. We study synthesis of o/w nanoemulsions stabilised by curcumin–Tween 80 mixture. The effects of curcumin concentration (0.009–0.072 wt%), different pH (2–10) conditions and salt concentration (0–500 mM) on emulsion droplet size and loading efficiency of curcumin are elucidated. Confocal laser microscopy technique is employed to visualise absorption of curcumin on the surface of oil droplets. FTIR spectroscopy is used to confirm hydrophobic and electrostatic interaction between curcumin and Tween 80. Curcumin-loading efficiency increased with increase in curcumin concentration and highest loading efficiency (94%) was observed at curcumin concentration of 0.072 wt%. The addition of curcumin had no influence on the emulsions’ initial droplet size (250–275 nm). Droplet size increased marginally due to coalescence after a month of storage, while curcumin loading efficiency reduced marginally (< 10%) for all curcumin concentrations. For pH 2–10, curcumin loading efficiency after 30 days of storage was ≥ 80% and highest loading efficiency (~ 90–93%) was observed at pH 6 and 7. For all the salt concentrations studied, droplet sizes and curcumin loading efficiency stayed constant (≥ 90%) for the period of 30 days.