Process intensification for curcumin nanodispersion preparation using subcritical water-Optimization and characterization

Curcumin, a natural and non-polar pigment of turmeric, was used to produce oil in water nanodispersion based on intensified process using subcritical water and Tween 20 as solvent and emulsifier, respectively. Response surface methodology was used to obtain optimum temperature, ranging 100-140 degrees C, and heating time, from 60 to 180 min, at constant pressure of 1.5 atm to prepare nanodispersions. Curcumin nanodispersion with minimum particles size of 15.15 nm and polydispersity index of 0.345, and maximum zeta potential of -13.24 mV was successfully formed using temperature and heating time of 115 degrees C and 155 min, respectively. Further analysis indicated that transparency colloidal solution containing dispersed and spherical curcumin nanoparticles had yellow colour with positive b* value of 2.75, L* value of 2.95 and turbidity of 0.065 NTU with apparent viscosity of 1.19 mPa.s. In addition, maximum loading ability of 0.181 g/L and efficiency of 90.5 %, and minimum total curcumin loss of 9.5 % were achieved at optimum preparation conditions. Results revealed that prepared curcumin nanodispersion had potent antioxidant activity (55.3%) with high bactericidal activity toward both S. aureus and E. coli, based on created clear zones with diameters of 26 and 24 mm, respectively.