Extraction of catechins from decaffeinated green tea for development of nanoemulsion using palm oil and sunflower oil based lipid carrier systems

Catechins were extracted using hot water at various temperatures from supercritical CO2 decaffeinated green tea. The catechins extract were encapsulated at a concentration of 0.1% (w/w) in lipid based nanoemulsion delivery systems using sunflower oil and palm oil with the combination of hydrophilic and lipophilic emulsifiers. Four different formulations were prepared in a two-step process involving high shear and high pressure homogenization. The formulations were characterized for their physicochemical properties such as mean emulsion size, pH, conductivity, refractive index, peroxide value and physical stability under accelerated aging. The presence of catechins in the encapsulated matrix was confirmed by conducting different chemical assays. The oxidation of nanoemulsions was successfully arrested by the catechins in all the formulations. Physically and chemically stable emulsions were obtained from sunflower oil with no significant variation in droplet diameter, conductivity, refractive index and pH up to 14 days.